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Animal Models Used to Study the Different Mechanisms Involved in the Gastric Mucosal Damage and in the Protection

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Gyula Mozsik and Imre Szabó

Submitted: March 6th, 2015 Published: March 9th, 2016

DOI: 10.5772/60505

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8.1. 24-hour pylorus-ligated rats

8.1.1. 24-hour pylorus-ligated rats alone

The peak of the membrane ATPase appears earlier than the gastric hypersecretion (Figure 73). When we prepared the membrane ATPase from the forestomach (rumen), we also found its peak earlier than the ulcer development (Shay et al., 1945) (Figure 74).

It is interesting to note that the changes in the membrane ATPase reached its peak at the same time in both stomach parts after pylorus-ligation (4 hours after the pyloric ligation). When we compared the sequence of biochemistry, gastric hypersecretion and ulcer development, we found a similar sequence to that in patients with antral, duodenal and jejunal ulcers.

The membrane ATPase can be specifically inhibited by ouabain application. This principal argument offers an approach to the changes in the gastric acid output and concentration) and ulcer development (Figures 75, 76).

The tissue level of cAMP decreased significantly in both parts of the rat stomach (Mózsik et al., 1978 a, c; Mózsik et al., 1979 a, b, c, d, e, f).

8.1.2. 24-hour pylorus-ligated rats after bilateral surgical vagotomy

After a 24-hour bilateral surgical vagotomy, the gastric acid secretory responses and gastric ulcer significantly decreased (Table 38), meanwhile the ATP–-ADP transformation significantly decreased in both glandular part and the forestomach (Figures 77, 78).

Figure 73.

Correlations between the changes in membrane ATPase activity and H+ output in 24-hour pylorus-ligated rats (means ± SEM) [Mózsik and Vizi: Amer. J. Dig. Dis. 21:449-454, 1976a) (with kind permission)].

Figure 74.

Correlation between the changes in membrane ATPase prepared from the forestomach and ulcer development in 24-hour pyloru-ligated rats (means ± SEM) [Mózsik Gy. and Vizi: Amer. J. Dig. Dis. 21:449-454, 1976a)(with kind permission)].

Figure 75.

Ouabain-induced inhibition of the membrane ATPase prepared from gastric fundic mucosa, volume of gastric secretion and H+ output in 24-hour pylorus-ligated rats dependent upon time after pyloric ligation (means ± SEM). [Mózsik and Vizi: Amer. J. Dig. Dis. 21:449–454, 1976a (with kind permission).]

Figure 76.

Ouabain-induced inhibition of the membrane ATPase prepared from the forestomach and ulcer development in 24-hour pylorus-ligated rats (means ± SEM) [Mózsik and Vizi: Amer. J. Dig. Dis. 21: 449–454, 1976a (with kind permission).]The tissue level of cAMP decreased significantly in both parts of the rat stomach (Mózsik et al., 1978 a, c; Mózsik et al., 1979 a, b, c, d, e, f).

Experimal parameters Pylorus ligation alone Pylorus ligation + bilateral surgical vagotomy
Volume of gastric secretion (mL/24 h) 15.4 ± 2.1 2.0 ± 0.3*
H+ output (µEq/ 24) 867 ± 50 130 ± 20*
H+ concentration (mEq/L) 55.2 ± 2.6 65 ± 10
Total number of ulcer in the forestomach/ 10 rats 86 0

Table 38.

Gastric secretory numbers (means ± SEM) and ulcer development (total ulcer/10 rats) in pylorus-ligated rats with and without bilateral surgical vagotomy. Abbreviation: * : P < 0.001. [Mózsik and Vizi: Dig. Dis. Sci. 22: 1072–1075, 1976b (with kind permission).]

Figure 77.

Changes in stomach wall ATP and ADP in the corpus of pylorus-ligated rats 24 hours after pylorus ligation, with and without bilateral surgical vagotomy. The results are expressed in nanomoles (means ± SEM of 10 rats). Abbreviations: A, sham-operated rats; B, pylorus-ligated rats; C, pylorus-ligated and surgically vagotomized rats. The ATP/ADP for A is significantly greater than that for B: P < 0.001. [Mózsik and Vizi: Dig. Dis. 22: 1072–1075, 1976b (with kind permission).]

Figure 78.

Changes in stomach wall ATP and ADP in the forestomach of rats 24 hours after pylorus ligation, with and without bilateral surgical vagotomy. The results are expressed in nanomoles (means ± SEM of 10 rats). Abbreviations: A, sham-operated rats; B, pylorus-ligated rats; C, pylorus-ligated and surgically vagotomized rats. The ATP/ADP for A is not significantly different from that for B. [Mózsik and Vizi: Dig. Dis. 22:1072–1075, 1976b (with kind permission).]

The stomach wall ATP and ADP have been studied in rats, with and without bilateral surgical vagotomy, 24 hours after pylorus ligation. It was observed that the amounts and concentrations significantly decreased in both parts (corpus + antrum and forestomach) in pylorus-ligated rats, whereas the amounts and concentrations remained significantly higher in pylorus-ligated + vagotomized rats. Changes in amounts and concentrations of ADP paralleled those of ATP. It has been concluded that a significant decrease of cellular ATP is necessary to produce gastric hypersecretion in ulceration in pylorus-ligated rats. This significant decrease of cellular ATP, in corpus + antrum and forestomach, can be prevented by bilateral surgical vagotomy (Mózsik and Vizi, 1976b).

8.2. Dynamic evaluation the changes of extra- and intracellular regulatory mechanisms of gastric cellular energy systems in pylorus-ligated rats without application of any drugs

As we mentioned earlier, the time period of 4 hours after pylorus ligation offers an ideal time to study the stimulatory or inhibitory actions of drugs, hormones and mediators given immediately after pylorus ligation (Figure 73). During this time period, gastric ulceration upon gastric hyperacidity never appears.

In the study, the fundus and forestomach in the rats were biochemically analyzed in depth to understand the drugs, hormones and mediators.

Table 39.

Biochemical constituents in the gastric fundic mucosa of intact rats.

Figure 79.

Changes in the cellular ATP, ADP, cAMP and AMP in the time period of first 5 hours dependent upon time after pyloric ligation. The observations were carried out on gastric fundic mucosa. The results obtained in sham-operated rats (normal state) were taken to be equal to 100% (means ± SEM). [Mozsik (2006) Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

The tissue levels of ATP, ADP, cAMP and AMP and the regulatory mechanisms between them were measured at 1, 2, 3, 4 and 5 hours after pylorus ligation (Figure 79, Table 39).

8.2.1. Biochemical backgrounds of effect of atropine in 4 hours pylorus-ligated rats

The atropine dose-dependently decreases the gastric H+ output (Figure 80). In these observations, the ADP was decreased dose-dependently, whereas the cAMP and AMP were increased in the rat gastric fundic mucosa (Figure 81).

Figure 80.

Dose-dependent inhibitory effect of atropine on the gastric acid secretion in 4-hour pylorus-ligated rats (means ± SEM). [Mózsik, Figler, Nagy, Patty, Tárnok (1981): Gastric and small intestinal energy metabolism in mucosal damage. In: Mózsik Gy., Hänninen O., Jávor T. (Eds.). Advances in Physiological Sciences. Vol. 29. Gastrointestinal Defence Mechanism. Pergamon Press, Oxford – Akadémiai Kiadó, Budapest. pp. 213–288 (with kind permission).]

Figure 81.

Atropine-induced changes in gastric H+ output, gastric fundic mucosal levels of ATP, ADP and AMP in 4-hour pylorus-ligated rats. The results were expressed as percent values obtained immediately after pylorus ligation (=100%), except for gastric H+ output, which was also expressed in percent values, but obtained at 4 hours after pylorus ligation (means ± SEM). [Mózsik, Figler, Nagy, Patty, Tárnok (1981): Gastric and small intestinal energy metabolism in mucosal damage. In: Mózsik Gy., Hänninen O., Jávor T. (Eds.). Advances in Physiological Sciences. Vol. 29. Gastrointestinal Defence Mechanism. Pergamon Press, Oxford – Akadémiai Kiadó, Budapest. pp. 213–288 (with kind permission).]

Similar changes were found in the forestomach during atropine treatment.

Schematic summary of atropine treatment-induced (given in different doses) gastric fundic mucosal damage in 4-hour pylorus-ligated rats (Figure 82).

Figure 82.

Biochemical changes in the regulatory steps of cellular energy systems in the gastric fundic mucosa produced by different (cytoprotective and antisecretory) doses of atropine in 4-hour pylorus-ligated rats.

8.2.2. Biochemical backgrounds of epinephrine in hours pylorus-ligated rats

Epinephrine dose-dependently decreased the gastric H+ output and gastric fundic mucosal level of ADP, whereas the cAMP level was increased (Shay et al., 1945) (Figures 83–85).

Similar changes were found in the forestomach after epinephrine administration to those in the rat gastric fundic mucosa.

Figure 85 indicates the main steps of epinephrine-induced regulatory pathways in the tissue levels of ATP, ADP, cAMP and AMP in the gastric fundic mucosa of 4-hour pylorus-ligated rats.

8.3. Biochemistry of aspirin-induced mucosal damage and its prevention by different compounds

8.3.1. Biochemistry of aspirin-induced mucosal damage in 4 hours pylorus-ligated rats

Aspirin is a specific inhibitor of cyclooxygenase (COX-1; Mózsik et al., 2003).

Earlier, Davernport and coworkers proved that aspirin breaks the gastric mucosal barrier, which increases the H+ backdiffusion.

We observed later (during the 1980s) that the transformation of ATP into ADP could be inhibited by aspirin administration (Figler et al., 1985, 1986, 1999).

Figure 83.

Dose-dependent inhibitory effect of epinephrine on the gastric acid secretion in 4-hour pylorus-ligated rats (means ± SEM). [Mózsik, Figler, Nagy, Patty, Tárnok (1981): Gastric and small intestinal energy metabolism in mucosal damage. In: Mózsik Gy., Hänninen O., Jávor T. (Eds.). Advances in Physiological Sciences. Vol. 29. Gastrointestinal Defence Mechanism. Pergamon Press, Oxford – Akadémiai Kiadó, Budapest. pp. 213–288 (with kind permission).]

Figure 84.

Epinephrine-induced changes in the fundic gastric mucosal levels of ADP and cAMP in comparison with the inhibition of gastric acid secretion (means ± SEM). [Mózsik, Figler, Nagy, Patty, Tárnok (1981): Gastric and small intestinal energy metabolism in mucosal damage. In: Mózsik Gy., Hänninen O., Jávor T. (Eds.). Advances in Physiological Sciences. Vol. 29. Gastrointestinal Defence Mechanism. Pergamon Press, Oxford – Akadémiai Kiadó, Budapest. pp. 213–288 (with kind permission).] For further explanation, see Figure 83.

Figure 85.

Epinephrine-induced changes in the regulatory mechanisms between the cellular ATP, ADP and AMP by different doses of epinephrine in 4-hour pylorus-ligated rats. The different doses of epinephrine were subcutaneously applied immediately after pyloric ligation (means ± SEM). For further explanation, see Figure 83.

In these studies, we analyzed the changes in the gastric H+ output and changes in the rat gastric fundic mucosa after aspirin administration (200 mg/kg dissolved in 2 mL of 150 mmoles of H+) given immediately after pylorus ligation.

Figure 83 demonstrates the effects of aspirin on 4-hour pylorus-ligated rats. The gastric H+ output, obtained at 0, 1 and 3 hours, was less than the quantity given immediately after pyloric ligation. The difference between the given acid and the measured acid output was taken as a marker of gastric H+ backdiffusion (Figure 86). This figure clearly indicates that the active gastric H+ secretion starts only from the second hour (Figler et al., 1985, 1986, 1999) (Figures 87, 88).

The results presented in Figure 84 demonstrate the absolute values of volume (mL/100 g body weight/4 hours), H+ output (μEq/100 b.w./4 hours) and glandular ulcer in 4-hour pylorus-ligated (A) and 4-hour pylorus-ligated plus aspirin (B) rats. The values of groups A and B are presented in Figure 87. The forthcoming figure (Figure 30) demonstrates the main changes in the rat gastric fundic mucosal biochemistry without (group A) and with (group B) aspirin administration (Figure 88).

Figure 89 demonstrates the correlations between the changes in the rat gastric fundic mucosal biochemistry without (group A) and with (group B) aspirin treatment. The values expressed the differences between the pylorus-ligated versus pylorus-ligated plus aspirin-treated rats (Figures 88, 89).

We tried to summarize the changes in the regulatory pathways between the tissue levels of ATP, ADP, cAMP and AMP in intact (untreated), 4-hour pylorus-ligated and 4-hour pylorus-ligated plus aspirin-treated rats (Figure 90).

Figure 86.

The balance between the aspirin-induced gastric H+ backdiffusion and active H+ secretion in 4-hour pylorus-ligated plus aspirin (200 mg/kg ig. in 2 mL = 300 μmoles of H+)-treated animals (means ± SEM). [Figler, Jávor, Nagy, Patty, Mózsik 1986. Int. J. Tiss. React. 8: 15–22 (with kind permission).]

Figure 87.

Changes in the volume (mL/100 g b.w./4 hours), acid output (μEq/100 g b.w./4 hours) in the 4-hour pylorus-ligated (A) versus. 4-hour pylorus-ligated plus aspirin-treated (B) rats. The Δ values expressed as difference between the groups of B versus A (means ± SEM). [(Figler, Jávor, Nagy, Patty, Mózsik 1986. Int. J. Tiss. React. 8: 15–22 (with kind permission).]

Figure 88.

The changes in the gastric fundic mucosal levels of ATP, ADP, AMP and cAMP in 4-hour pylorus-ligated (A) and 4-hour pylorus-ligated plus aspirin-treated (B) rats expressed as absolute values. The values of groups A versus B were given as Δ values (means ± SEM). [Figler, Jávor, Nagy, Patty, Mózsik 1986. Int. J. Tiss. React. 8: 15–22 (with kind permission).]

Figure 89.

The summary of the changes in the rat gastric fundic mucosa and ulcer development in 4-hour pylorus-ligated and 4-hour pylorus-ligated plus aspirin-treated animals.

Figure 90.

The details of the regulatory pathways in intact (left figure), in 4-hour pylorus-ligated (middle figure) and in 4-hour pylorus-ligated plus aspirin-treated rats (right figure) (means ± SEM).

8.3.2. Gastric mucosal-protective effect of atropine and its changes in biochemistry of gastric mucosa in 4-hour pylorus-ligated plus aspirin-treated rats

Following the observations presented before (as a section of 5.5.), the mucosal-protective effect of atropine was studied under the same experimental conditions. The gastric mucosal damage was produced after intragastric administration of 200 mg/kg aspirin (dissolved in 2 mL of 150 mmol HCl) immediately after pyloric ligation. The different doses of atropine (0.1, 0.5 and 1.0 mg/kg s.c.) given at the same time as that of aspirin in 4-hour pylorus-ligated rats (Figure 91).

Figure 91.

Experimental protocol for studies examined the mucosal-protective effect of atropine (given in doses of 0.1, 0.5 and 1.0 mg/kg subcutaneously immediately after pyloric ligation plus aspirin administration). [Figler et al., 1985, Digestion 31, 145–146 (with kind permission).]

The volume, concentration of H+, gastric acid output (Figure 92) and the number and sum of ulcers (Figure 93) could be decreased dose-dependently by the application of atropine (Figure 93).

The results of biochemical measurements [tissue levels of ATP, ADP and AMP (Figure 94)], adenylate pool, “energy charge”, ratio of ATP/ADP (Figure 95), tissue level of cAMP (Figure 96) and lactate (Figure 97) are provided.

The results clearly indicate that the ATP transformation is inhibited by atropine; however, its value decreases by the increase of atropine doses. In the background, the ATP transformation pathway will lead to an increase in ATP–cAMP transformation, whereas the ratio of ATP/ADP and “energy charge” increases; however, the adenylate pool and tissue level of lactate remained unchanged (Figure 98).

Figure 92.

Changes in gastric secretory responses in 4-hour pylorus-ligated plus aspirin-treated rats after application of different doses of atropine. The results are expressed as means ± SEM. Abbreviations: S, surgical interventions; S + A, surgical intervention plus aspirin treatment, n, indicates the number of animals. [Figler et al., 1985, Digestion 31, 145–146 (with kind permission).]

Figure 93.

Dose-dependent gastric mucosal-preventive effects of different doses of atropine in 4-hour pylorus-ligated plus aspirin-treated rats. The results are presented as means ± SEM. Abbreviations: S, surgical intervention; S + A, surgical intervention plus aspirin treatment; n, indicates the number of animals. [Figler et al., 1985, Digestion 31, 145–146 (with kind permission).]

Figure 94.

Atropine treatment-induced changes in adenylate pool, ratio of ATP/ADP and “energy charge” in the gastric mucosal tissues in 4-hour pylorus-ligated plus aspirin-treated rats. The results are expressed as means ± SEM. Abbreviations: S, surgical intervention; S + A, surgical intervention plus aspirin treatment; n, indicates the number of animals. [Figler et al., 1985, Digestion 31, 145–146 (with kind permission).]

Figure 95.

Atropine treatment-induced changes in adenylate pool, ratio of ATP/ADP and “energy charge” in the gastric mucosal tissues in 4-hour pylorus-ligated plus aspirin-treated rats. The results are expressed as means ± SEM. Abbreviations: S, surgical intervention; S + A, surgical intervention plus aspirin treatment; n, indicates the number of animals. [Figler et al., 1985, Digestion 31, 145–146 (with kind permission).]

Figure 96.

Atropine-induced changes in tissue level of cAMP in the gastric mucosa in 4-hour pylorus-ligated plus aspirin-treated rats. The results are expressed as means ± SEM. Abbreviations: S, surgical intervention; S + A, surgical intervention plus aspirin treatment; n, indicates the number of animals. [Figler et al., 1985, Digestion 31, 145–146 (with kind permission).]

Figure 97.

Effect of atropine treatment on the tissue level of lactate in the gastric mucosa of 4-hour pylorus-ligated plus aspirin-treated rats. The results are expressed as means ± SEM. Abbreviations: S, surgical intervention; S + A, surgical intervention plus atropine treatment; n, indicates the number of animals. [Figler et al., 1985, Digestion 31, 145–146 (with kind permission).]

Figure 98.

Schematic representation of changes in the extra- and intercellular feedback mechanisms, which exist after application of different doses of atropine. The different steps in the regulatory mechanisms were expressed by the results based on the changes in perpetual values of tissue levels of ATP, ADP, AMP and cAMP of the pathological (pylorus-ligated plus aspirin-treated) values (and these were taken as 100%).

Consequently, the intracellular regulatory mechanism between the energy systems also significantly changes in the gastric mucosa during the development of gastric mucosal protection by atropine.

8.3.3. Gastric mucosal-protective effects of vitamin A and β-carotene and their biochemical backgrounds in 4-hour pylorus-ligated plus aspirin-treated rats

In the previous sections (5.5. and 5.5.1.), the biochemical changes in the gastric mucosa and gastric secretory responses were studied in the 4-hour pylorus-ligated plus aspirin-treated rats during the time of development of gastric mucosal damage (5.5.) and prevention by atropine (5.5.1).

In this chapter, the 4-hour pylorus-ligated plus aspirin-treated ulcer model was further used; however, the actions of mechanisms of two scavengers (namely vitamin A and β-carotene) were studied. As indicated earlier, these compounds have no gastric secretory inhibitory actions neither in animals (Jávor et al., 1983) nor in human beings (Mózsik et al., 1986). Consequently, the scavenger action versus cytoprotection phenomenon were together studied in the aspirin animal model.

The experimental protocol and different measurements (gastric secretory responses, gastric mucosal lesions and biochemical measurements) are presented in Figure 99.

Figure 99.

Experimental protocol (design) for the studies of actions of mechanisms of gastric mucosal protection of orally administered vitamin A and β-carotene (vitamin A and β-carotene were dissolved in oleum helianthi and given intragastrically in doses of 0.01, 0.1, 1.0 and 10.0 mg/kg by a flexible nasogastric tube). [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission).]

Figure 100.

Changes in the volume of gastric secretion in 4-hour pylorus-ligated (A) and aspirin-treated (B) rats with and without vitamin A and β-carotene treatment (right side of the figure). The detailed results are presented in the figure. [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission).]

The volume of gastric secretion and acid output did not change in 4-hour pylorus-ligated plus aspirin-treated rats (B) versus pylorus-ligated rats alone (A), the volume decreased after the application of higher doses (1.0 and 10.0 mg/kg) (Figure 100); however, no changes were found in the gastric acid secretion (Figure 101).

Figure 101.

No change in the gastric acid secretion in 4-hour pylorus-ligated ligated plus aspirin-treated rats after intragastrically given vitamin A and β-carotene. [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission).]

Figure 102.

Gastric mucosal-preventive effect (on number of lesions) of vitamin A and β- carotene on 4-hour pylorus-ligated plus aspirin-treated rats. [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission).]

Both vitamin A and β-carotene dose-dependently prevented the number (Figure 102) and severity (Figure 103), which differ from the decrease of gastric acid secretion (Figure 101).

Figure 103.

Gastric mucosal (severity)-preventive effects of vitamin A and β-carotene on 4-hour pylorus-ligated plus aspirin-treated rats. [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission).]

Figure 104.

Changes in the gastric mucosal ATP in 4-hour pylorus-ligated and aspirin-treated rats after intragastric administration of vitamin A and β-carotene (given intragastrically in different doses). [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission).]

Figure 105.

Changes in the gastric mucosal ADP in 4-hour pylorus-ligated plus aspirin-treated rats after administration of vitamin A and β-carotene (given intragastrically in different doses). [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission).]

Figure 106.

Changes in the gastric mucosal AMP in 4-hour pylorus-ligated plus aspirin-treated rats after administration of vitamin A and β-carotene (given intragastrically in different doses). [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission).]

Figure 107.

Changes in the gastric mucosal cAMP in 4-hour pylorus-ligated plus aspirin-treated rats after administration of vitamin A and β-carotene (given intragastrically in different doses). [Mozsik et al. Inflammopharmacology 11:560-562, 2003 (with kind permission).]

Figure 108.

ATP/ADP ratio in the gastric mucosa in 4-hour pylorus-ligated plus aspirin-treated rats after administration of vitamin A and β-carotene (given intragastrically in different doses). [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission).]

Figure 109.

Changes in the gastric mucosal levels of adenylate pool (ATP + ADP + AMP) in 4-hour pylorus-ligated plus aspirin-treated rats after administration of vitamin A and β-carotene (given intragastrically in different doses). [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission)].

Figure 110.

Changes in the gastric mucosal level of “energy charge” in 4-hour pylorus-ligated plus aspirin-treated rats after administration of vitamin A and β-carotene (given intragastrically in different doses). [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission).]

The tissue level of ATP (Figure 104), ADP (Figure 105), AMP (Figure 106) and cAMP (Figure 107) dose-dependently increased by intragastric administration of vitamin A and β-carotene in the animal model, whereas the ratio of ATP/ADP (Figure 108), adenylate pool (ATP+ADP+AMP) (Figure 109) and “energy charge“ (Figure 110) did not change.

The actions of vitamin A and β-carotene on the gastric secretory responses, mucosal damage and biochemical parameters of gastric mucosal tissues produced by intragastric administration (in doses of 0.01, 0.1, 1.0 and 10.0 mg/kg) are summarized in Table 40.

Table 40.

Correlation between gastric mucosal-preventive effects of vitamin A and β-carotene (given in doses of 0.01, 0.1, 1.0 and 10.0 mg/kg i.g.) versus the changes in gastric secretory responses and biochemical parameters in the gastric mucosa of rats treated with sodium salicylate (200 mg/kg dissolved in 2 mL of 150 mmol/L i.g.) in 4-h pylorus-ligated rats). [Mozsik et al. Inflammopharmacology 11:560–562, 2003 (with kind permission).]

8.4. Effect of indomethacin (IND) in 4-hour rats

8.4.1. Biochemical mechanisms of indomethacin-induced gastric mucosal damage in rats (4 hours)

The value of ED5O was identified for indomethacin (Djahanguiri, 1969; Karádi and Mózsik, 2000) and their value was obtained in 20 mg/kg. When IND (20 mg/kg s.c.) was given immediately after pylorus ligation, no significant decrease was obtained neither in gastric volume nor in gastric H+ output. The tissue levels of ATP, AMP and cAMP decreased significantly (Király et al., 1992 a, b; Morón et al., 1982, 1983, 1984 a, b, c; Mózsik et al., 1992 b, f; Rumi et al., 2001 a, b) (Figures 111–114).

The number of ulcers in the glandular stomach was 15 ± 2, and the severity was 16 ± 2 in the indomethacin-treated animals.

The following changes in the cellular ATP-dependent energy systems were obtained in the gastric fundic mucosa of 4-hour indomethacin-treated rats: significant decrease of ATP (P < 0.001) and AMP (P < 0.05) and cAMP (P < 0.001), ratio of ATP/ADP (P < 0.001), adenylate pool (P < 0.05), ADP increased (P < 0.0.5) and changes were found in “energy charge” and tissue level of lactate. The correlation between the decrease of cAMP and indomethacin-induced gastric mucosal damage will be detailed in Section 8.4.4.

Figure 111.

Experimental design of the study with 4-hour indomethacin-treated rats.

Figure 112.

Changes in tissue levels of gastric mucosal ATP, ADP and AMP in 4-hour indomethacin-treated rats.

Figure 113.

Changes in ratio of ATP/ADP, adenylate pool (ATP + ADP + AMP) and “energy charge” [(ATP + 0.5 ADP)/(ATP + ADP + AMP)] in gastric fundic mucosa of 4-hour indomethacin-treated rats.

Figure 114.

Changes in tissue levels of cAMP and lactate in the gastric fundic mucosa of 4-hour indomethacin-treated rats.

8.4.2. Comparative biochemical studies between the gastric-protective effects and biochemical mechanisms (tissue levels of ATP, ADP, cAMP and AMP) of atropine and cimetidine in the gastric mucosa of rats treated with indomethacin

Both atropine and cimetidine decreased dose-dependently and significantly the number (Figure 115) and severity (Figure 116).

It was interesting to note that atropine dose-dependently increased, whereas cimetidine decreased the tissue level of ATP (Figure 117), and the tissue levels of ADP could be decreased by atropine and increased by cimetidine (Figure 118). Consequently, these atropine- and cimetidine-induced changes in the tissue levels of ATP and ADP significantly modified the ratio of ATP/ADP (Figure 119), the AMP increased dose-dependently by atropine, whereas its value dose-dependently decreased (Mózsik et al., 1992f) (Figure 120).

The values of adenylate pool (ATP + ADP + AMP) were unchanged (Figure 121). The “energy charge” also did not change because of treatment with atropine or cimetidine (Figure 122). The tissue level of cAMP dose-dependently increased by atropine, whereas its value decreased by cimetidine (Figure 123).

When we measured the tissue level of lactate, we found no significant changes in case of atropine or in cimetidine (Figure 124). In the gastric juice, we could not demonstrate the presence of parenterally applied Evans blue (Figure 125).

Figures 126 (a, b) demonstrate the difference in actions of atropine and cimetidine in 4-hours rats. Although both drugs inhibit the IND-induced gastric mucosal damage, however, their biochemical effects completely differed from each other’s.

Figure 115.

Effects of atropine and cimetidine on the number of gastric mucosal lesions in 4-hour indomethacin (IND)-treated rats. The small doses of atropine (0.025 mg/kg) and cimetidine (2.5 mg/kg) represent the cytoprotective dose of both drugs. C: indicates the results obtained from the saline-treated rats, IND: indicates the groups of animals treated with IND (20 mg/kg s.c.) alone or with atropine and cimetidine. P values are between the IND-treated versus IND plus atropine or IND-treated plus cimetidine-treated groups (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).]

Figure 116.

Effects of atropine or cimetidine on the severity of gastric mucosal damage produced by IND (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).]

Figure 117.

Changes in the gastric mucosal level of ATP produced by atropine and cimetidine in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).] For further explanation, see Figure 115.

Figure 118.

Changes in the gastric mucosal levels of ADP produced by atropine or cimetidine in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).] For further explanation, see Figure 115.

Figure 119.

Changes in the ratio of ATP/ADP of gastric mucosa in 4-hour IND-treated rats produced by atropine or cimetidine (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).] For further explanation, see Figure 115.

Figure 120.

Changes in the gastric mucosal level of AMP produced by atropine or cimetidine in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).] For further explanation, see Figure 115.

Figure 121.

Changes in the gastric mucosal level of adenylate pool (ATP + ADP + AMP) produced by atropine or cimetidine in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).] For further explanation, see Figure 115.

Figure 122.

Changes in the values of “energy charge” produced by atropine or cimetidine in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).] For further explanation, see Figure 115.

Figure 123.

Changes in the gastric mucosal level of cAMP produced by atropine or cimetidine in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).] For further explanation, see Figure 126 a, b.

Figure 124.

Changes in the gastric mucosal levels of lactate produced by atropine or cimetidine in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).]

Figure 125.

Concentration of Evan’s blue in the serum, adherent gastric mucus and gastric juice produced by atropine or cimetidine in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).] For further explanation, see Figure 115.

Figure 126.

(a) Summary of the biochemical results obtained in the gastric fundic mucosa produced by atropine or cimetidine in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).] For further explanation, see Figure 115. (b) Feedback mechanism between the membrane-bound ATP-dependent energy systems produced by cytoprotective and antisecretory doses of atropine or cimetidine in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Exp. Clin. Gastroenterol. 3, 205–215, l992a (with kind permission).]

These results clearly proved that the changes in the biochemical parameters in gastric fundic mucosa are significantly opposite in case of administration of atropine and cimetidine in 4-hour indomethacin-treated rats.

8.4.3. Biochemical backgrounds of gastric mucosal-protective effect of vitamin A in 4-hour indomethacin-treated rats

Vitamin A, β-carotene and other retinoids are not able to decrease the gastric acid outputs neither in pylorus-ligated rats nor in healthy human subjects. It was interesting to study the effects of vitamin A in 4-hour pylorus-ligated plus indomethacin-treated rats. In these studies, the tissue levels of ATP, ADP, cAMP and AMP were measured besides the inhibitory effects on the number and severity of IND-induced gastric mucosal damage (Figures 127,128).

Figure 127.

Experimental protocol for the study of gastroprotective and metabolic effects of vitamin A on 4-hour IND-treated rats. [Mózsik et al.: Int. J. Tiss. Reac. 11, 65–71, 1989c (with kind permission).]

Vitamin A dose-dependently decreased in both the number and severity of IND-induced gastric mucosal damage (Figure 128). During the development of gastric mucosal effect, the tissue levels of ATP significantly decreased in association with the significant increase of tissue ADP (Mózsik and Jávor, 1991; Mózsik et al., 1989c, 1996a) (Figure 129).

No change was obtained in the adenylate pool (Figure 130). It was interesting to note that the dose-dependent increase of cAMP (Figure 131) also increased slightly the “energy charge” and the ratio of ATP/ADP (Figure 132).

Figure 128.

Changes in the number and severity of gastric mucosal lesions prevented by the application of different doses of vitamin A in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Int. J. Tiss. Reac. 11, 65–71, 1989c (with kind permission).]

Figure 129.

Changes in the gastric mucosal levels of ATP, ADP, AMP produced by vitamin A in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Int. J. Tiss. Reac. 11, 65–71, 1989c (with kind permission).]

Figure 130.

Changes in the gastric mucosal levels of adenylate pool and lactate produced by vitamin A in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Int. J. Tiss. Reac. 11, 65–71, 1989c (with kind permission).]

Figure 131.

Changes in the gastric mucosal level of cAMP produced by vitamin A in 4-hour IND-treated rats (means ± SEM). [Mózsik et al.: Int. J. Tiss. Reac. 11, 65–71, 1989c (with kind permission).]

Figure 132.

Changes in the gastric mucosal “energy charge” and ratio of ATP/ADP produced by vitamin A in 4-hour IND-treated rats (means ± SEM). [Mózsik et al. Int. J. Tiss. Reac. 11, 65–71, 1989c (with kind permission).]

Figure 133.

Regulatory pathways between the IND-induced gastric mucosal damage and vitamin A-induced changes in the 4-hour indomethacin-treated rat gastric fundic mucosa (means ± SEM). [Mózsik et al.: Int. J. Tiss. Reac. 11, 65–71, 1989c (with kind permission).]

When the changes in tissue levels of ATP, ADP, AMP and cAMP and the number of gastric mucosal damage were simultaneously compared, similar changes were obtained as those by atropine (Figure 133).

8.4.4. Gastroprotective effect of β-carotene differs from the prostaglandin system in 4-hour indomethacin-treated rats

The details of the gastric mucosal-protective effect of vitamin A were studied – in a dose-dependent manner – in the previous Section (8.4.3). In this section, the correlations between the gastric mucosal-protective effect of β-carotene (as a provitamin for vitamin A), gastric mucosal levels of PGE2 and cAMP were analyzed depending on the application of different doses of β-carotene and on time (the examinations were carried out at the 1, 2, 3 and 4 hours after indomethacin application) in indomethacin-treated rats. Earlier, it was proved that the carotenoids (including the β-carotene) prevent the chemically induced gastric mucosal damage (Jávor et al., 1983) by cytoprotection (without decreasing the gastric acid secretion).

The aims of these observations were as follows:

  1. To evaluate the details of β-carotene-induced gastric mucosal prevention in rat model experiment;

  2. Indomethacin produces inhibitory effect of the prostaglandin synthesis (and we proved this in rats in Section 8.4.3.) in 4-hour indomethacin-treated rats;

  3. To evaluate the possible correlations between the changes (decrease vs. development of indomethacin ulcer and increase vs. mucosal protection) of tissue levels of PGE2 in indomethacin-treated rats;

  4. To find (and to prove) the existence of β-carotene-induced mucosal protection versus changes (increase) in the gastric mucosal level of PGE2 system; and

  5. Is it really a well-established scientific fact that β-carotene produces only the scavenger pathway?

The experimental protocols (Figure 134) and the main results are presented in Figure 135.

Figure 136 indicated that a close correlation exists between the gastric fundic mucosal level of cAMP at 4 hours of experiments. We also indicated in many experiments that the responsible biochemical changes appeared earlier than the macroscopic appearance of gastric mucosal damage. So it was suggested that a similar correlation exists between the cAMP level in the gastric fundic mucosa versus clinical appearance of gastric mucosal damage, therefore the correlation between the tissue level of cAMP in the gastric fundic mucosa at 1 hour versus macroscopic images (number and severity) at 4 hours after indomethacin administration. Figures 137 and 138 clearly proved these correlations were clearly positive between these parameters.

When β-carotene (given intragastrically at doses of 0.1, 1.0 and 10 mg/kg dissolved in oleum helianthi) was given, then both the number (Figure 139) and severity (Figure 140) decreased dose-dependently. Interestingly, β-carotene produced a dose-dependent increase in the gastric fundic mucosal level of cAMP at 1 hour and at 4 hours after indomethacin administration (Figure 141).

Figure 134.

Design of the animal experiments in rats. [Mózsik, Bódis, Karádi, Király, Nagy, Rumi, Sütő, Szabó (1998). Inflammopharmacology 6: 27–40 (with kind permission).]

Figure 135.

Correlations between the development of gastric mucosal damage (number and severity), changes in the tissue levels of PGE2 and cAMP in the gastric fundic mucosa of 4-hour indomethacin-treated rats (at 0, 1, 2, 3 and 4 hours after administration of indomethacin). [Mózsik, Bódis, Karádi, Király, Nagy, Rumi, Sütő, Szabó (1998). Inflammopharmacology 6: 27–40 (with kind permission).]

Figure 136.

Correlation between the decrease of gastric mucosal level of cAMP (at 4 hours) versus number (and severity) (at 4 hours) in the gastric fundic mucosal damage in 4-hour indomethacin-treated rats. [Mózsik, Bódis, Karádi, Király, Nagy, Rumi, Sütő, Szabó (1998). Inflammopharmacology 6: 27–40 (with kind permission).]

Figure 137.

Correlations between the decrease of gastric fundic mucosal level of cAMP at 1 hour versus gastric mucosal damage (number and severity) at 4 hours in 4-hour indomethacin-treated rats. [Mózsik, Bódis, Karádi, Király, Nagy, Rumi, Sütő, Szabó (1998). Inflammopharmacology 6: 27–40 (with kind permission).]

Figure 138.

Similar results were obtained between the ∆ values of decrease in gastric fundic mucosal level of cAMP (∆ 0–1 hour after IND) versus number and severity (expressed in percent values) (at 4 hours after IND) in 4-hour indomethacin-treated rats. This figure indicates that the existence of this correlation is practically the same in cases of both development of number and severity of gastric mucosal damage in 4-hour indomethacin-treated rats. [Mózsik, Bódis, Karádi, Király, Nagy, Rumi, Sütő, Szabó (1998). Inflammopharmacology 6: 27–40 (with kind permission).]

Figure 139.

β-carotene-induced gastric fundic mucosal protection in 4-hour indomethacin-treated rats. The ordinate indicates the number of lesions, while the abscissa shows the time (in hours) after indomethacin administration. [Mózsik, Bódis, Karádi, Király, Nagy, Rumi, Sütő, Szabó (1998). Inflammopharmacology 6: 27–40 (with kind permission).]

Figure 140.

β-carotene-induced gastric fundic mucosal protection in 4-hour indomethacin-treated rats. The ordinate indicates the severity of lesions, while the abscissa shows the time (in hours) after indomethacin administration. [Mózsik, Bódis, Karádi, Király, Nagy, Rumi, Sütő, Szabó (1998). Inflammopharmacology 6: 27–40 (with kind permission).]

No similar correlations were obtained between the changes in the gastric fundic mucosal PGE2 level versus development of the gastric mucosal damage (and/or protection). The conclusions are as follows:

  1. The decrease of cAMP in the gastric fundic mucosa appears at 1 hour after administration of indomethacin, and its level shows a moderate increase in the time period from 1 to 4 hours in 4-hour indomethacin-treated rats;

  2. The extent of decrease of tissue levels of PGE2 and cAMP differ significantly (including the different time periods) in 4-hour indomethacin-treated rats;

Figure 141.

Correlations between the ∆ values of gastric fundic mucosal level of cAMP at 1 hour (left figure) and at 4 hours (right figure) versus mucosal-protective effect of β-carotene on the severity of gastric mucosal damage (expressed in percent values) in 4-hour indomethacin-treated rats. [Mózsik, Bódis, Karádi, Király, Nagy, Rumi, Sütő, Szabó (1998). Inflammopharmacology 6: 27–40 (with kind permission).]

  1. β-carotene, in a dose-dependent manner, prevents the indomethacin-induced gastric mucosal damage in association with dose- and time-dependent increase of gastric fundic mucosal cAMP level; however, no increase in gastric fundic mucosal PGE2 was obtained during β-carotene-induced gastric mucosal damage;

  2. β-carotene-induced gastric mucosal protection (in indomethacin model) differs from the gastric mucosal level of PGE2;

  3. The decrease in gastric fundic mucosal cAMP is a responsible intracellular signal for the development of indomethacin-induced gastric mucosal damage, and the increase of cAMP by β-carotene is responsible for the development of β-carotene-induced gastric mucosal protection;

  4. The treatment with vitamin A and β-carotene produces gastric mucosal protection against indomethacin-induced mucosal damage by a very complex extra- and intracellularly existing regulatory systems of the membrane-bound ATP-dependent energy systems in the rat gastric mucosa (Mózsik et al., 1990 a, b, c).

8.5. Changes in the gastric mucosal energy systems during 5-hour stress in rats

The aims of this study were as follows:

  1. To evaluate the changes in the membrane-bound ATP-dependent energy systems during the development of stress-induced gastric mucosal damage;

  2. To prove (or to exclude) the presence of tissue hypoxia in the rat gastric mucosa during development of gastric mucosal damage;

  3. To present further evidence of a feedback mechanism existing between ATP-ADP and ATP-cAMP transformations;

  4. To analyze the different biochemical changes in the gastric mucosa before and after macroscopic appearance of gastric mucosal damage; and

  5. To study the direct effect of epinephrine, cAMP and AMP on Na+-K+-dependent ATPase prepared from the rat gastric fundic mucosa.

The animals were forced to swim in water below the body temperature (24 oC) for maximally 5 hours. They were sacrificed at 0, 1, 2, 3, 4 and 5 hours after the introduction of stress. The stress produced gastric mucosal lesions in the glandular portion of the stomach (its incidence is 100%). After sacrificing the animals (at the different times after the introduction of stress) (Figure 142), the number (and severity) of gastric mucosal lesions was registered and different biochemical examinations were carried out from the rat gastric fundic mucosa as the following:

  1. The measurements of tissue levels of ATP, ADP, AMP, lactate and cAMP (and different calculations of the obtained results were performed between the results obtained in the measurements);

  2. The preparation of membrane (Mg2+-dependent and Na+–K+-dependent) ATPase was prepared and its activity was measured;

  3. The effects of epinephrine, cAMP and AMP were measured on the Na+–K+-dependent ATPase activity prepared from the rat gastric fundic mucosa (for details, see Mózsik et al., 1990a).

Figure 142.

Experimental protocol of study of stress-induced gastric ulcer in rats [Mózsik et al., Ann N Y Acad Sci 597: 264–281, 1990a (with kind permission).]

The macroscopic appearance of gastric fundic mucosal lesions could be detected at the 2nd hour after the introduction of stress (Nagy et al., 1982, 1983; Mózsik et al., 1990a) (Figure 143). The results of biochemical examinations are presented in Figures 114–156 and Table 41.

Figure 143.

Macroscopic appearance of gastric mucosal lesions (number and severity) after the introduction of stress (means ± SEM) [Mózsik et al., Ann N Y Acad Sci 597: 264–281, 1990a (with kind permission).]

Figure 144.

Changes in gastric mucosal level of adenosine triphosphate (ATP) during the development of stress-induced gastric mucosal lesions in rats. [Mózsik et al., Ann N Y Acad Sci 597: 264–281, 1990a (with kind permission).]

Figure 145.

Changes in gastric mucosal level of adenosine diphosphate (ADP) during the development of stress-induced gastric mucosal lesions in rats. [Mózsik et al., Ann N Y Acad Sci 597: 264–281, 1990a (with kind permission).]

Figure 146.

Stress-induced changes in the ratio of ATP–ADP (ATP/ADP) in the gastric mucosa of rats. [Mózsik et al., Ann N Y Acad Sci 597: 264–281, 1990a (with kind permission).]

Figure 147.

Changes in gastric mucosal level of adenosine monophosphate (AMP) during the development of stress-induced gastric mucosal lesions in rats. (Mózsik et al., Ann N Y Acad Sci 597: 264–281, 1990a (with kind permission).]

Figure 148.

Changes in gastric mucosal level of cyclic adenosine monophosphate (cAMP) during the development of stress-induced gastric mucosal lesions in rats. [Mózsik et al., Ann N Y Acad Sci 597: 264–281, 1990a (with kind permission).]

Figure 149.

Tissue levels of adenylate pool (ATP + ADP + AMP) in the gastric mucosa during the development of stress-induced gastric mucosal lesions in rats. [Mózsik et al., Ann N Y Acad Sci 597: 264–281, 1990a (with kind permission).]

Figure 150.

Gastric mucosal level of lactate during the development of stress-induced gastric mucosal lesions in rats. [Mózsik et al., Ann N Y Acad Sci 597: 264–281, 1990a (with kind permission).]

Figure 151.

Changes in the gastric mucosal level of “energy charge” [(ATP + 0.5 ADP)/(ATP + ADP + AMP)] during the development of stress-induced gastric mucosal lesions in rats. [Mózsik et al., Ann N Y Acad Sci 597: 264–281, 1990a (with kind permission).]

Figure 152.

Correlations between changes in energy systems and development of gastric mucosal lesions in rats. Changes in the gastric mucosal levels of ATP, ADP, AMP and cAMP are expressed as ∆ values. [Mózsik et al., Ann N Y Acad Sci 597: 264–281, 1990a (with kind permission).]

It was interesting to note that cAMP decreased significantly in 24 and 4 hours, with the increased level of cAMP being associated with gastric mucosal prevention in many models (pylorus-ligated plus IND-treated animals and the effects of atropine and vitamin A) (Mózsik et al., 1978c; 1979 a, b; 1988a, b; 1992 a, b, c, d, e; 1996 a, b; 1997 b, c; 1998).

Figure 153.

Regulatory mechanisms between the tissue levels of ATP, ADP, AMP and cAMP during stress-induced gastric mucosal biochemistry (means ± SEM). [Mózsik et al., Ann N Y Acad Sci 597, 264–281, l990 (with kind permission).]

Drugs pD2 pA2 α
Epinephrine 8.60 8.40 0.41
cAMP 11.80 10.00 0.48
AMP 8.80 8.70 0.90
Oabain 5.90 5.80 1.00

Table 41.

Values of affinities (pD2) and intrinsic activities (pA2) (αatropine = 1.00) for epinephrine, cAMP, AMP and ouabain on Na+–K+-dependent ATPase activity prepared from the rat gastric fundic mucosa. The necessary dose to produce 50% action of affinity (pD2) and intrinsic activity (pA2) is expressed in [−] molar values. [Mózsik et al., Ann N Y Acad Sci 59, 264–281, 1990a (with kind permission).]

We followed the changes in the ratio of ATP/ADP and “energy charge” (Figure 154). No significant change in ATP/ADP was found.

Figure 154.

Changes in the ratio of ATP/ADP and in “energy charge” dependent upon time after the introduction of stress (means ± SEM). [Mózsik et al., Ann N Y Acad Sci 59, 264–281, 1990a (with kind permission).]

Figure 155.

Time-sequence changes between the macroscopic development of gastric mucosal damage and biochemical parameters in the gastric fundic mucosa dependent upon time after the introduction of stress (means ± SEM). [Mózsik et al., Ann N Y Acad Sci 59, 264–281, 1990a (with kind permission).]

Figure 156.

Affinity and intrinsic activity curves for inhibition by epinephrine, cAMP, AMP and ouabain of Na+–K+-dependent ATPase prepared from the rat gastric fundic mucosa. [Mózsik et al., Ann N Y Acad Sci 59, 264–281, 1990a (with kind permission).]

The results presented in this chapter are as follows:

  1. Gastric mucosal lesions appeared and increased gradually 3 hours after the introduction of stress;

  2. The extent of ATP–cAMP and cAMP–AMP transformations was increased considerably during the development of stress ulcer;

  3. The extent of ATP–ADP transformation was completely inhibited;

  4. The activity of Na+–K+-dependent ATPase from the rat gastric fundic mucosa could be inhibited by epinephrine, cAMP and AMP;

  5. The ratio of ATP/ADP was unchanged during the first time period (from 0 to 3 hours), after its value increased;

  6. The value of “energy charge” (e.g., the extent of phosphorylation and/or dephosphorylation) of cells was decreased at 2 and 3 hours, after which its value returned to a normal level;

  7. There was no increase in the tissue level of lactate;

  8. Several biochemical changes (decrease of ATP, ADP and “energy charge”, increase of cAMP and AMP) preceded the macroscopic appearance of stress ulcer.

Figure 157.

Suggested extra- and intracellular regulatory steps existing between the Na+–K+-dependent ATPase (transformation of ATP into ADP) and adenylate cyclase (transformation of ATP into cAMP) under physiological (basic) state of the target organ. It is important to emphasize that the different drugs, hormones and mediators (“first messengers”) are able to modify the in smaller concentrations the Na+–K+-dependent ATPase system, and only in higher doses the adenylate cyclase, and the ATP as a common substrate cellular components for the function of both enzymes in presence of Mg2+. [Mózsik et al., Ann N Y Acad Sci 59, 264–281, 1990a (with kind permission).]

For a better understanding, the existence of feedback extra- and intracellular regulatory mechanism system between the different membrane-bound ATP-dependent energy systems (under physiological and pathological conditions existing in the gastric fundic tissues) and the different (suggested) regulatory steps are demonstrated in Figures 157–160.

Figure 158.

A detailed summary of the existence of the extra- and intracellular regulatory steps between the Na+–K+-dependent ATPase (ATP transformation of ATP into ADP) and adenylate cyclase (ATP transformation into cAMP) enzymes in the gastric fundic mucosa under physiological (basic) state. [Mózsik et al., Ann N Y Acad Sci 59, 264–281, 1990a (with kind permission).]

Figure 159.

The epinephrine-induced changes in Na+–K+-dependent ATPase, adenylate cyclase prepared from the rat gastric fundic mucosa and in the tissue levels of ATP, ADP, AMP and cAMP in the rat gastric fundic mucosa. [Mózsik et al., Ann N Y Acad Sci 59, 264–281, 1990a (with kind permission).]

Figure 160.

Summary of the changes in the feedback mechanism system during stress-induced gastric ulcer in rats (in comparison with each step to the existing physiological state). [Mózsik et al., Ann N Y Acad Sci 59, 264–281, 1990a (with kind permission).]

8.6. Reserpine ulcer and gastric mucosal biochemistry in rats

Reserpine liberates epinephrine and norepinephrine in the rats. If the animals receive reserpine (5 mg/kg) after 6 hours, visible ulceration will appear in the glandular stomach (Mózsik et al., 1983c) (Figure 161).

Figure 161.

Ulcer (number and severity) development in reserpine (5 mg/kg s.c.)-induced gastric fundic mucosal lesions dependent upon time after reserpine administration (means ± SEM). [Mózsik et al., Acta Physiol Hung 62, 107–112, 1983c (with kind permission).]

It was interesting to note that significant changes could be detected before the ulcer development; the peaks of the biochemical measurements were obtained at 6–12 hours after reserpine administration (Figures 162–164), whereas the peak of ulceration was obtained at 24 hours after reserpine administration.

Figure 162.

The time sequence between the biochemical changes (tissue levels of ATP, ADP, AMP and cAMP) versus gastric fundic mucosal damage ulcer (number and severity) in reserpine-treated rats (means ± SEM). [Mózsik et al., Acta Physiol Hung 62, 107–112, 1983c (with kind permission).]

Figure 163.

Correlations between the changes in “energy charge” and ratio of ATP/ADP versus gastric fundic mucosal damage (number and severity) produced by reserpine administration dependent on time after reserpine administration (means ± SEM). [Mózsik et al., Acta Physiol Hung 62, 107–112, 1983a (with kind permission).]

Figure 164.

The correlations between the changes in the tissue levels of ATP, ADP, AMP, adenylate pool, ratio of ATP/ADP, cAMP versus ulcer (number and severity) development dependent on time after reserpine administration (means ± SEM). [Mózsik et al., Acta Physiol Hung 62, 107–112, 1983a (with kind permission).]

8.7. NaOH-, NaCl-, HCl- and ethanol-induced gastric mucosal damage in rats (1 hour): different chemically induced gastric mucosal damage versus same changes in the gastric mucosal biochemical backgrounds

The gastric fundic mucosal damage was first produced by Chaudhury and Jacobson (1978) and Robert and coworkers (1979), when they clearly indicated that the gastric mucosal damage was prevented by small doses of prostaglandins (PGs) without the presence of any inhibitory effect on the gastric acid secretion in rats. This event was the first evidence for that the gastric mucosal prevention can be separated from the importance of gastric acid secretion (that was the old dogma in the treatment of PUD). This step in the gastroenterological research offered a better understanding of patients’ problems to the existing principal basic (experimental) research. Furthermore, these types of experimental approaches provide new results, which were responsible, and simple methods (Morón et al., 1983, 1984c; Mózsik et al, 1980; 1981a; 1983b; 1984 a, b, c, d; 1989 a, b, c, d, e; 1990b).

8.7.1. A model study of ethanol-induced injury to gastric mucosa in rats

Rats were given 96% ethanol intragastrically, and they were sacrificed at 0, 1, 5, 15, 30 and 60 minutes later. At each time period, the number and severity of mucosal lesions were recorded. At the same time intervals, the tissue levels of ATP, ADP, AMP and lactate were determined in homogenates of gastric mucosa by enzymatic methods. Tissue content of cAMP was determined by RIA (Becton Dickinson, Orangeburg, USA). The protein content was measured by the method of Lowry et al. (1951). The tissue levels of ATP, ADP, AMP and lactate are expressed as nmoles/mg protein, except for cAMP, which is expressed as pmoles mucosal protein. The ratio of ATP/ADP, values of adenylate pool (ATP + ADP + ANP) and “energy charge” [(ATP + 0.5 ADP)/(ATP + ADP + AMP)] were calculated from the individual values (Figures 165–173, Table 42).

Time periods after ethanol administration (min)
0 to 5 5 to 15
(∆ 10 min)
15 to 30
(∆ 15 min)
30 to 60
(∆ 30 min)
Number of
gastric mucosal lesions
5.85 ± 0.60
(5.85)*
3.67 ± 1.00
(1.82)*
1.30 ± 0.40
(0.32)*
3.00 ± 0.80
(0.50)*
Severity of gastric mucosal esions 28 ± 2
(28)*
9 ± 1
( 4.5)*
13 ± 1
(4.3)*
12 ± 2
(2)*

Table 42.

Changes in macroscopically appearing gastric mucosal damage produced by intragastric administration of ethanol and time dependence after administration (means ± SEM) (n=12).* = average value per 5 minutes corresponding to different time periods after ethanol administration. [Mózsik and Javor: Dig. Dis. Sci. 33:92–105, 1988 (with kind permission).]

Figure 165.

Macroscopic appearance of gastric mucosal damage in rats produced by intragastric administration of 96% ethanol. Time dependence after administration of ethanol. [Mózsik and Javor: Dig. Dis. Sci. 33:92–105, 1988 (with kind permission).]

Figure 166.

Changes in gastric mucosal level of ATP in rats after intragastric administration of 96% ethanol (1 mL). [Mózsik and Javor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

Figure 167.

Changes in gastric mucosal level of ADP in rats after intragastric administration of 96% ethanol (1 mL). [Mózsik and Javor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

Figure 168.

Changes in ratio of ATP/ADP in the gastric mucosa of rats after administration of 96% ethanol (1 mL). [Mózsik and Javor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

Figure 169.

Changes in gastric mucosal level of AMP in rats after intragastric administration of 96% ethanol (1 mL). [Mózsik and Javor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

Figure 170.

Changes in gastric mucosal level of adenylate pool of rats after intragastric administration of 96% ethanol (1 mL). [Mózsik and Javor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

Figure 171.

Changes in gastric mucosal level of cAMP of rats after intragastric administration of 96% ethanol (1 mL). [Mózsik and Javor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

Figure 172.

Changes in “energy charge” [(ATP + 0.5 ADP)/(ATP + ADP + AMP)] in the gastric mucosa after intragastric administration of 96% ethanol (1 mL). [Mózsik and Javor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

Figure 173.

Gastric mucosal level of lactate in rats after intragastric administration of 96% ethanol (1 mL). [Mózsik and Javor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

The tissue level of ATP did not change during the first 5 min. It decreased from 15 to 60 minutes after ethanol administration, but then increased again at 60 minutes compared with levels at 15 and 30 minutes after ethanol administration. The tissue level of ADP decreased during the first 15 minutes and then returned to pretreatment values at 30 and 60 minutes after ethanol administration. The ratio of ATP/ADP increased over the first 5 minutes and then decreased. The tissue level of AMP was decreased during the first hour. The value of adenylate pool was decreased at all time intervals. The tissue level of cAMP increased at 1 and 5 minutes after ethanol administration and decreased thereafter. The extent of phosphorylation and/or dephosphorylation as estimated by Atkinson’s formula was decreased at 15 and 30 minutes after ethanol administration. Surprisingly, there was no change in the tissue level of lactate independently of the presence of macroscopic mucosal injury.

Gastric mucosal damage appeared macroscopically after 5 min. It occurred to half the extent of that present after 1 hour following the exposure to ethanol. The tissue level of ATP did not decrease, whereas the ratio of ATP/ADP and tissue level of cAMP increased. There was no increase in the levels of ADP, AMP or lactate during the first 5 minutes after ethanol administration. It can be concluded that the presence of mucosal hypoxia before and at the time of appearance of macroscopic mucosal damage after ethanol administration can be excluded.

8.7.2. Extra- and intracellular regulatory mechanism system in the gastric mucosa during the development of ethanol-induced gastric mucosal damage in rats

If the changes in tissue levels of ATP, ADP, AMP and cAMP are expressed in percent values at 0 minute (intact animals) dependent upon time after the administration of ethanol, then two different characteristic changes can be found in the gastric mucosa: the cAMP level significantly increased together with of the inhibition of ATP transformation into ADP at 5 minutes; thereafter (from 5 to 60 minutes), the tissue level of cAMP decreased in association with increase in tissue level of ADP and gradually increasing tissue level of ATP by intact oxidative phosphorylation. The critical evaluation of these changes in the membrane-bound ATP-dependent energy systems offers us to demonstrate the existence of feedback systems between the ATP–ADP and ATP–cAMP transformations in the gastric mucosa during the development of ethanol-induced macroscopic damage (in vivo examinations) (Figure 174).

Figure 174.

Feedback mechanisms between ATP–ADP, ATP–cAMP systems in the rat gastric mucosa after intragastric administration of 96% (1 mL) ethanol. [Mózsik and Javor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

8.7.3. Comparison of development of gastric mucosal damage and gastric mucosal biochemistry in acid-dependent (HCl) and nonacid-dependent (ETOH) experimental models in rats

The time dependence of gastric fundic mucosal damage (number and severity) appeared in time order after the application of HCl or ethanol (ETOH). The extent of gastric fundic mucosal damage reaches its value in about 50% at 5 minutes after the administration of necrotizing agents (Figures 175, 176).

The extent of ATP–ADP transformation significantly increased at 0–5 minutes after the administration of necrotizing agents (Figures 177, 178), whereas the ATP–cAMP transformation decreased significantly (Figures 179). During this time period, no elevation was obtained in the tissue level of lactate (Figure 180). The different necrotizing agents were applied (presently HCl and ETOH); however, the biochemical changes in the rat gastric mucosa were found to be the same (Figure 181).

Figure 175.

Macroscopic appearance of the number of gastric mucosal damage in rats treated with ethanol (ETOH) (1 mL of 96 v/v and HCl (1 mL, 0.6 M HCl i.g.) dependent on time after administration of necrotizing agents. The results were expressed as means ± SEM of 12 animals. P values were calculated as results between 0 versus different times (*) and results obtained at the same time in ETOH and HCl models (+) (means ± SEM; P < 0.5; P< 0.001; P < 0.100). [Gasztonyi et al., Inflammopharmacology 4, 351–360, 1996 (with kind permission).]

Figure 176.

Macroscopic appearance of sum of gastric mucosal damage in rats with ETOH and HCl models (means ± SEM). [Gasztonyi et al., Inflammopharmacology 4, 351–360, 1996 (with kind permission).]

Figure 177.

Changes in the gastric mucosal level of ATP in rats with ETOH- and HCl-treated rats after application of necrotizing agents (means ± SEM). [Gasztonyi et al., Inflammopharmacology 4, 351–360, 1996 (with kind permission).]

Figure 178.

Changes in the gastric mucosal level of ADP in ETOH- and HCl-treated rats dependent upon time after application of necrotizing agents (means ± SEM). [Gasztonyi et al., Inflammopharmacology 4, 351–360, 1996 (with kind permission).]

Figure 179.

Changes in gastric mucosal cAMP of rats treated with ETOH or HCl dependent on time after administration of necrotizing agents (means ± SEM). [Gasztonyi et al., Inflammopharmacology 4, 351–360, 1996 (with kind permission).]

Figure 180.

Gastric mucosal level of lactate in rats treated with ETOH and HCl dependent upon time after application of necrotizing agents (means ± SEM). For further explanation, see Figure 175. [Gasztonyi et al., Inflammopharmacology 4, 351–360, 1996 (with kind permission).]

The biochemical measurements were carried out in the HCl-, NaOH-, NaCl- and ethanol-induced models, and the summary of these results is given in Figure 182. Although the necrotizing agents differ significantly, the biochemical changes in the rat gastric mucosa are quite similar (Figure 182). Very similar changes were obtained in the ratio of ATP/ADP and “energy charge” (Figure 183).

Figure 181.

Changes in the gastric fundic mucosal levels of biochemistry, gastric mucosal damage (number and severity) in ETOH or HCl models (means ± SEM). [Gasztonyi et al., Inflammopharmacology 4, 351–360, 1996 (with kind permission).]

Figure 182.

The schematic representation of regulatory pathways between the tissue levels of ATP, ADP, AMP and cAMP, values of ATP/ADP, “adenylate pool” and “energy charge” as well as the development of gastric mucosal lesions in chemicals [(1 mL from 96 v/v, 1 mL from 0.2 M NaOH, 1 mL from 25 v/v NaCl and 1 mL 0.6 M HCl)]. [Mózsik (2006): Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 183.

The changes in the regulatory pathways between the tissue level of ATP, ADP, AMP and cAMP in the intact (untreated) and in HCl models. The same results were obtained in the HCl model, 25% NaCl and 96% ETOH (means ± SEM). [Mózsik (2006): Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

8.7.4. Dynamism of extra- and intracellular regulatory mechanisms in the ethanol-induced gastric mucosal damage in 1-hour experiments dependent on time after intragastric application of ethanol

The changes in the regulatory pathways between the tissue levels of ATP, ADP, cAMP and AMP are indicated in Figure 184 dependent upon time after the administration of ethanol. This figure demonstrates well that the changes in the cellular energy systems significantly dynamically change from time to time in the rat gastric fundic mucosa; however, the ATP resynthesis worked well in this tissue.

The changes in the membrane-bound ATP-dependent energy systems in the gastric fundic mucosa were the same in the other models, independent from the kinds of intragastric application of 0.2 M NaOH, 25% NaCl, 0.6 M HCl and 96% ethanol.

Figure 184.

Changes in the cellular regulatory mechanisms of energy systems in ethanol (ETOH) induced in the rat gastric fundic mucosa dependent on time after intragastric administration of ETOH (1 mL from 96%). [Mózsik (2006): Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

8.7.5. Biochemical backgrounds of gastric mucosal-protective effects of cytoprotective and antisecretory doses of atropine and cimetidine in acid-dependent model in rats (1-hour model)

After the classical cytoprotective agents (PGE2 and PGI2), the gastric mucosal-protective effect of different antisecretory drugs was studied (given in different doses) in animal experiments. It was suggested that all the drugs having antisecretory properties are able to produce gastric mucosal protection without the presence of any antisecretory activities. We studied these problems in cases of atropine and cimetidine (Figure 185).

Figure 185.

Changes in biochemical parameters of cellular energy systems and lactate in the gastric fundic mucosa in HCl model of rats. [Mózsik (2006): Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

We studied the gastric mucosal-preventive effect of atropine (given in doses of 0.025, 0.2 and 1.0 mg/kg s.c.). The 0.025-mg/kg atropine indicated mucosal protection in the HCl model, together with significant changes in the gastric fundic mucosa, without the presence of inhibitory effect on gastric acid secretion. It was interesting to note that the gastric mucosal protection and the biochemical changes in the gastric fundic mucosa differ only in their extents.

The evaluation of quantitative changes produced by “cytoprotective” doses of atropine and cimetidine is presented in Figures 186 and 187.

These figures indicate that very complex intracellular mechanisms exist in the gastric fundic mucosa of rats produced by the gastric mucosal-protective effects of cytoprotective and antisecretory doses of atropine and cimetidine; however, it is clear that the original cellular regulatory mechanisms by PGI2 (5 µg/kg), atropine (0.025 mg/kg) and cimetidine (2.5 mg/kg) also differ from each other (Figure 188).

Figure 186.

Comparison between changes in cellular energy systems of gastric fundic mucosa of rats produced by cytoprotective (0.025 mg/kg) and antisecretory (1.0 mg/kg) doses of atropine. The changes in the antisecretory dose of atropine are expressed in percent of cytoprotective dose (= 100%).

Figure 187.

Comparison between changes in cellular energy systems of gastric fundic mucosa of rats produced by cytoprotective (2.5 mg/kg) and antisecretory (50 mg/kg) doses of cimetidine. The changes of antisecretory dose of atropine are expressed in percent of cytoprotective dose (= 100%).

Figure 188.

Comparison of the cellular regulatory mechanisms (steps) in the gastric fundic mucosa of rats produced by cytoprotective doses (5 µg/kg), atropine (0.025 mg/kg) and cimetidine (2.5 mg/kg). The changes in the different parameters of the cellular energy systems are presented in percent values of control (untreated) rats (100% values).

Figure 189.

The extra- and intracellular regulatory mechanism system in intact (untreated) and in HCl-treated rats. The results obtained from the untreated rats were taken to be equal to 100%, and the changes in the HCl-treated rats expressed as changes in percent values in comparison with the normal (100) values.

Bilateral surgical vagotomy completely inhibited the volume and gastric H+ output together with complete prevention of gastric ulcer (Mózsik and Vizi, 1976 a, b). It was surprising that the tissue level of ATP after surgical vagotomy remained (Mózsik and Vizi, 1976 a, b) neither in the glandular stomach nor in the forestomach. These results suggested that the tissue level of ATP must break down for the energy liberation and development of gastric secretory responses and ulcer development (Mózsik et al., 1993 a, b, 2001 a, b).

When the chemical vagotomy (i.g. atropine administration) was carried out, the tissue levels of ATP decreased significantly and the tissue levels of ADP and AMP were increased (Figures 80, 81). The tissue levels of cAMP were found to be significantly higher after chemical vagotomy than after bilateral surgical vagotomy (Karádi and Mózsik, 2000; Mózsik et al., 1981a, b; 1987a; 1996b; Vincze et al., 1992, 1993a) (Figures 81, 190).

Figure 190.

The effect of bilateral surgical vagotomy in the gastric secretory responses (volume and H+ output) in 4-hour pylorus-ligated rats (means ± SEM). [Mózsik and Vizi, Am J Digest Dis 22, 1072–1075, 1976 (with kind permission).]

The best conclusions of these observations were as follows:

  1. The ATP breakdown in the glandular stomach and forestomach is basically necessary to obtain gastric hypersecretion as well gastric ulceration;

  2. Represents an intracellular regulatory mechanism to obtain a gastric hypersecretion;

  3. In case of chemical vagotomy, the significant increase of mucosal cAMP probably represents an important regulatory step against the development of gastric hypersecretion (Karádi and Mózsik, 2000).

Previously, gastric ulceration was considered to appear as a result of extremely decreased tissue ATP produced by the impaired oxidative phosphorylation. However, we first demonstrated that the gastric ulceration in the forestomach appears as the consequence of active biochemical mechanisms of the gastric tissues (Mózsik et al., 1967 a, b; 1969 b, c).

These results also demonstrated that the intracellular mechanism systems differ significantly in the rat stomach after surgical and chemical vagotomy.

Figure 191.

The effect of bilateral surgical vagotomy on the gastric tissue levels of cAMP in pylorus-ligated rats (means ± SEM). [Mózsik and Vizi, Amer J Digest Dis 22, 1072–1075, 1976 (with kind permission).]

8.8. “Surgical” and “chemical” vagotomy on the biochemistry of gastric mucosa in 1-hour rats

The results of these observations are presented in Section 4.3.2.

8.8.1. “Surgical” vagotomy inhibits the PGI2 –induced gastric mucosal-protective effect in rats

The surgical vagotomy alone cannot produce any ulcer development in the rat stomach; however, Sikiric and coworkers found the appearance of ulcer in the rat stomach (Mózsik et al., 1981a; 1990 b, c; Karádi and Mózsik, 2000).

After bilateral surgical vagotomy, the extent of IND-induced gastric mucosal lesion was found to be increased, whereas the chemical vagotomy significantly decreased the gastric mucosal damage to chemicals.

The interpretation of these results led to the following conclusions:

  1. The intact vagal nerve is basically necessary for the mechanisms involved in different chemically induced gastric mucosal damage;

  2. The gastric mucosal-protective effects significantly differ from each other against chemically induced gastric mucosal damage.

These results were presented in a Satellite Symposium of the Congress of International Union of Physiological Sciences (IUPS) (Budapest, Hungary, 1980) [Mózsik, Hänninen and Jávor (1981) (eds.) Advances in the Physiological Sciences. Vol. 29, Gastrointestinal Mucosal Defence. Pergamon Press, Oxford – Akadémiai Kiadó, Budapest] (Figure 192).

These type of observations were published in the Journal of Prostaglandins, Leucotrienes and Medicine (Mózsik, Moron, Jávor, 9: 71–84, 1982), in which we also emphasized on the essential role of the intact vagal nerve for the development of gastric mucosal-preventive effect of prostacyclin against the chemically induced mucosal damage, e.g., this protective effect of prostacyclin was not present in these animal models. We concluded from the results of these observations that the intact vagal nerve is basically necessary for the gastric mucosal protection.

Figure 192.

The presentation (first in the world) of PGI2 gastric-protective effect disappears after bilateral surgical vagotomy in rats treated with ETOH (96 v/v) (means ± SEM). [Jávor et al., (1981) Gastric mucosal resistance to physical and chemical stress. In: Mózsik Gy., Hänninen O., Jávor T. (Eds.) Advances in the Physiological Sciences. Vol. 29. Gastrointestinal Mucosal Defence. Pergamon Press, Oxford – Akadémiai Kiadó, Budapest. pp. 141–159 (with kind permission).]

Similar observations were published by Miller (Amer J Physiol. 245: 601–623, 1983), and Henagen, Seidel and Miller cited our results in their forthcoming paper (Gastroenterology 84: 1186, 1983); however, from time to time, our priority has been the key role of the intact vagal nerve in the gastric mucosal defense mechanisms (Karádi and Mózsik, 2001; Király et al., 1992b; Mózsik, 2006 a, b; Mózsik et al., 1990a, 1991a, 2001b; Vincze et al., 1992, 1993a, 1997).

However, it is important to emphasize that the “chemical vagotomy” (atropine treatment) does not clinically inhibit the appearance of prostaglandin- and prostacyclin-induced gastric mucosal protection against the chemically induced mucosal damage in animals.

We need to emphasize well that surgical vagotomy is widely used in the clinical practice of treatment of patients with peptic ulcer. We never accepted the application of surgical vagotomy in the medical practice and we emphasized the application of “chemical vagotomy” in the medical treatment of patients with peptic ulcer (see Chapter 2).

8.9. Biochemical backgrounds of the PGI2–induced gastric mucosal protection against by different chemicals in rats

When small doses (5 and 50 μg/kg) of PG2 were given, both the number (Figure 193) and severity (Figure 194) dose-dependently decreased and surprisingly the tissue level of ATP practically decreased to a value of zero (Figure 195). The tissue level of ADP (Figure 196), cAMP (Figure 197) and AMP (Figure 198) increased, and the values of ATP/ADP were practically zero (Mózsik et al., 1983b) (Figure 199).

Figure 193.

Preventive effects of PGI2 on the number of gastric lesions produced by topical application of 0.2 M NaOH, 25%, 0.6 M HCl and 96% ethanol (means ± SEM). [Mózsik et al., Prostagland. Leucot. Med. 12, 423–436, 1983 (with kind permission).]

Figure 194.

Gastric-preventive effects of PGI2 on the severity in 0.2 M NaOH, 0.6 M HCl, 25% NaCl and 96% ethanol (means ± SEM). [Mózsik et al., Prostagland. Leucot. Med. 12, 423–436, 1983 (with kind permission).]

Figure 195.

Changes in the gastric fundic mucosal level of ATP during development of gastric mucosal damage produced by different necrotizing agents (left side of the figure) and of different doses of PGI2 (right side of figure). The differences in the results obtained in the normal pathological state (O) indicate the changes in the levels of ATP during the development of gastric mucosal damage (means ± SEM). [Mózsik et al., Prostagland. Leucot. Med. 12, 423–436, 1983 (with kind permission).]

Figure 196.

Changes in the gastric fundic mucosal level of ADP during mucosal damage produced by different necrotizing agents (left side) and of PGI2-induced gastric mucosal protection (means ± SEM). [Mózsik et al., Prostagland. Leucot. Med. 12, 423–436, 1983 (with kind permission).]

Figure 197.

Changes in the gastric fundic mucosal level of cAMP during the development of gastric mucosal damage and of PGI2-induced gastric cytoprotection (means ± SEM). [Mózsik et al., Prostagland. Leucot. Med. 12, 423–436, 1983 (with kind permission).]

Figure 198.

Changes in the gastric mucosal level of AMP during the development of gastric mucosal damage produced by different necrotizing agents and of PGI2-induced gastric cytoprotection (means ± SEM). [Mózsik et al., Prostagland. Leucot. Med. 12, 423–436, 1983 (with kind permission).]

Figure 199.

Changes in the ratio of ATP/ADP in the rat gastric fundic mucosa during the development of gastric mucosal damage produced by different necrotizing agents and of PGI2-induced gastric cytoprotection (means ± SEM). [Mózsik et al., Prostagland. Leucot. Med 12, 423–436, 1983 (with kind permission).]

The results of these observations indicated the following:

  1. The different chemically induced mucosal acute gastric mucosal damages are practically the same (during 1-hour time period) in relation to the time dependence of mucosal damage and its biochemical backgrounds (in membrane-bound ATP-dependent energy systems);

  2. The prostacyclin-induced gastric mucosal-preventive effects are the same in different experimental models (produced by 0.6 M HCl, 0.2 M NaOH, 25% NaCl solution and 96% ethanol) in relation to time dependence of macroscopic detectable patterns of defensive actions and to changes in the membrane-bound ATP-dependent energy systems in the rat gastric mucosa;

  3. It was very surprising to note that the tissue levels of ATP in the rat gastric mucosa practically reached the value of zero in the rat gastric mucosa, when the prostacyclin-induced mucosal-protective effects are present in the different animal models;

  4. The prostacyclin (and other prostaglandins) inhibits the extent of ATP transformation into ADP (in vitro conditions) in smaller concentrations, whereas they stimulate the ATP transformation into cAMP. These steps of the regulatory steps of prostacyclin are present in different chemically induced experimental models (under in vivo conditions);

  5. The results indicated similar changes in the regulatory feedback mechanisms of different chemical agents (drugs) to those we received in other experimental models.

8.10. Similarities and differences of PGI2- and ß-carotene-induced gastric mucosal protections and their biochemical actions in an acid-dependent (HCl) and in a non-acid dependent (ETOH) experimental model in rats

8.10.1. Gastric mucosal protective effect of PGI2 versus changes in the gastric mucosal energy systems in HCl model in rat

The experimental protocol and the obtained results are presented in Figure 200. The 5 µg/kg PGI2 was found as ED50 value (Figure 201). The PGI2 prevented the HCl-induced gastric mucosal damage (Figures 202, 203), and this inhibition appeared in the early period after the administration of HCl (Figures 203–211). In all biochemical parameters of the gastric mucosal biochemistry, the PGI2 produced dose-dependent actions (Mózsik et al., 1983b; 1984a; 1989 a, b; 1990 b, c; 1998; Sütő et al., 1989; Vincze et al., 1993a, 1997; Garamszegi et al., 1989; Gasztonyi et al., 1996).

Figure 200.

Experimental protocol for study of PGI2-induced gastric mucosal-preventive effects and their biochemical changes in HCl model. [Mózsik Gy. (2006) Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005) Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 201.

Determination of ED5O value for PGI2 in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005) Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 202.

Inhibitory effect of PGI2 on the number of gastric mucosal damage (means ± SEM) in the HCl model. [Mózsik Gy. (2006).Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005) Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 203.

Inhibitory effect of PGI2 on the sum of the ulcer severity in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005) Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 204.

Dose–response changes produced by PGI2 in the rat gastric fundic mucosal level of ATP (means ± SEM in HCl model). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005) Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 205.

Dose–response changes produced by PGI2 in the rat gastric fundic mucosal level of ADP in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005) Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 206.

Changes in the values of ATP/ADP produced by PGI2 in the rat gastric mucosa in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005) Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 207.

Dose–response changes in the rat gastric fundic mucosal level of AMP produced by PGI2 in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005) Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 208.

Dose–response changes in the rat gastric fundic mucosal levels of adenylate pool produced by PGI2 in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 209.

Dose–response changes in the rat gastric fundic mucosal levels of cAMP produced by PGI2 in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 210.

Changes in the rat gastric fundic mucosal level of “energy charge” produced by PGI2 in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 211.

PGI2-induced effects on the rat gastric fundic mucosal levels of lactate produced by PGI2 in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

8.10.2. Gastric mucosal protective effect of PGI2 versus changes in the gastric mucosal enery systems in ethanol (ETOH) model in rat

The dose of 5 µg/kg was also found as the value of ED5O in the ETOH model (Figure 213). The actions of PGI2 were found to be dose-dependent (Figures 214–222), except for the tissue level of lactate because its level was unchanged (Figure 222).

Figure 212.

Experimental protocol for the study of gastric fundic mucosal-preventive effect of PGI2 and its biochemical background in ethanol (ETOH) (nonacid-dependent) model. [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 213.

Determination of ED5O value for PGI2 in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 214.

PGI2-induced gastric mucosal-preventive effect (number) in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 215.

PGI2-induced gastric mucosal-preventive effect on the severity in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 216.

Dose-dependent changes produced by PGI2 in the tissue levels of ATP of the rat gastric fundic mucosa in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 217.

Dose-dependent changes produced by PGI2 in the gastric fundic mucosal level of ADP in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 218.

PGI2-induced changes in the gastric fundic mucosal level of ATP/ADP in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 219.

Dose-dependent changes in the rat gastric fundic mucosal level of AMP produced by PGI2 in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 220.

Dose-dependent changes in the rat gastric fundic mucosal level of cAMP produced by PGI2 in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 221.

Changes in the rat gastric fundic mucosal level of “energy charge” produced by PGI2 in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 222.

PGI2-induced changes in the rat gastric fundic mucosal level of lactate in ETOH model (means ±SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

It was interesting to note that the PGI2-induced gastric mucosal-preventive effect appears in the first (0–15 min) time period as that obtained by PGI2 in the HCl model.

The biochemically obtained results indicated dose-dependent actions on the tissue levels of ATP, ADP, AMP and cAMP and changes in the values of ratio of ATP/ADP, and the adenylate pool was found to be about the same.

8.10.3. Gastric mucosal-preventive effect of β-carotene versus changes in the gastric mucosal energy systems in HCl model in rats

β-carotene (given in 1 and 10 mg/kg doses i.g.) led to significant and dose-dependent prevention of the gastric mucosal damage (Figures 222, 223). The 1 mg/kg β-carotene produced the ED5O value in the HCl model (Figure 223). It was also interesting to note that β-carotene-induced gastric mucosal prevention appears later (from 15 to 60 min) (Figures 225, 226). The ATP–ADP transformation was decreased, whereas the ATP–cAMP transformation was increased (Figures 227–230). No significant changes were obtained in the adenylate pool (Figure 231) and the tissue level of lactate (Figure 232).

Figure 223.

Experimental protocol for the study of gastric mucosal-preventive effects and their biochemistry produced by β-carotene in HCl model. [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 224.

Determination of ED5O values for gastric fundic mucosal-preventive effects of β-carotene in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Dose-dependent gastric mucosal-preventive effect (number) of β-carotene in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 226.

Dose-dependent gastric mucosal-protective effect (severity) of β-carotene in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 227.

Dose-dependent changes in the rat gastric fundic mucosal level of ADP produced by β-carotene in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 228.

Changes in the gastric fundic mucosal level of ATP/ADP produced by β-carotene in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 229.

Changes in the rat gastric fundic mucosal level of AMP produced by β-carotene in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 230.

Changes in the rat gastric fundic mucosal level of cAMP produced by β-carotene in HCl model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 231.

“Energy charge” in the rat gastric fundic mucosal level in HCl model before and after β-carotene treatment (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 232.

Tissue levels of lactate in the rat gastric fundic mucosa in HCl model before and after β-carotene treatment (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

8.10.4. Mucosal-preventive effect of β-carotene versus changes in the gastric mucosal energy systems in ETOH model in rats

β-carotene showed gastric mucosal-preventive effect in ETOH model (Jávor et al., 1983; Mózsik and Jávor, 1981) (Figures 232–243).

The ED5O was also found for 1 mg/kg of β-carotene (i.g. given) (Figure 234). The gastric mucosal effect of β-carotene was also found in the later (from 15 to 60 min) time in order to number and severity of gastric mucosal damage (Figures 235–236). The ATP–ADP transformation was decreased, whereas the ATP–cAMP transformation was increased (Figures 237–241). No significant changes were obtained in the adenylate pool, “energy charge” and lactate (Figures 242, 243).

The results of our observations obtained from HCl- and ethanol-induced gastric mucosal damage and their gastric mucosal-preventive effects produced by PGI2 and β-carotene (including the changes in the membrane-bound ATP-dependent energy systems) allowed us to evaluate the details of their mechanisms in the development of gastric mucosal damage (HCl and ethanol) and PGI2 and β-carotene-induced gastric mucosal prevention (under animal experiments):

  1. HCl and ethanol (as mucosal-damaging chemical agents with different chemical properties) produce the same macroscopic appearance of gastric mucosal damage after their applications;

  2. The macroscopic appearance of gastric mucosal damage produced by HCl and ethanol indicated the same patterns of time sequences (in order of number and severity) of the development of gastric mucosal tissues;

  3. PGI2 and β-carotene exert gastric mucosal protection against HCl- and ethanol-induced gastric mucosal damage; however, their gastroprotective effects differ (from each other) in time after the administration of necrotizing agents: PGI2 acts earlier (from 0 to 15 min), whereas β-carotene is gastroprotective and it can be detected later (from 15 to 60 min) after the administration of necrotizing agents;

  4. The extent of ATP transformation into ADP is increased during the development of gastric mucosal damage produced by HCl and ethanol in the gastric fundic mucosa (in association with a small increase of gastric mucosal cAMP level) in both models;

Figure 233.

Experimental protocol for the study of gastric mucosal-protective effects and their biochemistry of β-carotene in ETOH model. [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

  1. The gastric mucosal-preventive effects of PGI2 and β-carotene associate with the decrease of ATP transformation into ADP and increase of ATP transformation into cAMP in the rat gastric fundic mucosa;

  2. PGI2 and β-carotene produce dose-dependent biochemical responses in the rat gastric mucosa (ATP, ADP, AMP, cAMP and adenylate pool) during the development of gastric mucosal-preventive protection against the chemically induced gastric mucosal damage;

  3. The biochemical mechanisms (changes in the membrane-bound ATP-dependent energy systems) of gastric mucosal-protective effects of PGI2 and β-carotene are the same in the HCl- and ethanol-induced mucosa;

  4. Biochemically, no presence of gastric hypoxemia was proved in the rat gastric fundic mucosa during the development of both gastric mucosal damage (by HCl and ethanol) and gastric mucosal protection of PGI2 and β-carotene against HCl and ethanol.

Figure 234.

Determination of ED5O value for the gastric mucosal-protective effect of β-carotene in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission)].

8.11. Interrelationships between the changes in parameters of oxygen free radical systems versus cellular energy systems in the gastric mucosa in acid-dependent (HCl) and nonacid-dependent (ETOH) experimental models during the time of development of gastric mucosal damage and gastric mucosal prevention produced by PGI2 and β-carotene

Many observations indicated clearly that the maintenance of good equilibrium (between the aggressive and defensive mechanisms) is an extremely complicated summary (result) in the living organs. We are able to learn and recognize different aspects of this extremely complicated equilibrium in the living organs, and our knowledge has changed over time.

The researchers are able to approach only some small piece from the whole, meanwhile many-many processes (regulatory pathways) are running beside each others. We are willing to hope that the selected piece(s) (to be used in the studies) is (are) an important field(s) for the whole screening method to understand the key point(s) in the keeping of this equilibrium between the aggressive and defensive factors.

Figure 235.

β-carotene-induced gastric mucosal-preventive effects on the rat gastric fundic mucosa (number) in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 236.

β-carotene-induced gastric fundic mucosal-preventive effect (on the severity) in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 237.

β-carotene-induced changes in the rat gastric fundic mucosal level of ATP in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 238.

β-carotene-induced changes in the rat gastric fundic mucosal levels of ADP in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 239.

β-carotene-induced changes in ratio of ATP/ADP of the rat gastric fundic mucosa in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 240.

β-carotene-induced changes in the rat gastric mucosal levels of AMP in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 241.

β-carotene-induced changes in the rat gastric fundic mucosal levels of cAMP in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 242.

“Energy charge” in the rat gastric fundic mucosa with and without application of β-carotene in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

Figure 243.

Lactate levels in the rat gastric fundic mucosa produced by β-carotene in ETOH model (means ± SEM). [Mózsik Gy. (2006). Molecular pharmacology and biochemistry of gastroduodenal mucosal damage and protection. In: Mózsik Gy. (Ed.) Discoveries in Gastroenterology (1960–2005). Akadémiai Kiadó, Budapest. pp. 139–224 (with kind permission).]

One of these fields is the oxygen free radical system, which incorporates different endogen enzyme systems (catalase, peroxidase, reduced glutathione peroxidase and superoxide dismutase) and many internal (vitamin C, vitamins A and E) and other external (chemical) components.

The production of oxygen free radicals and the compensation with different antioxidant compounds (scavengers) came into the focus of research. An excellent handbook was published (Laher, 2014), in which these problems were overviewed in the different organs (including the cellular, organ and body levels of living organisms).

We were also involved in this field of the studies (Bódis et al., 1995 a, b; 1996, 1997 a, b; 1998; 2000; Mózsik et al., 2001a; Szabó et al., 1996, 1997 a, b, c; 2000, 2012, 2014).

In these observations, systematic observations were carried out in the experimental models as those detailed in Section 8.10.

In the forthcoming sections, we demonstrate the tendencies of changes of oxygen free radical systems in comparison with the changes in the cellular energy systems in the gastrointestinal tract.

The superoxide dismutase (SOD) activity was determined according to the method of Misra and Fridovich (1972), which was modified by Matkovics et al. (1977). The glutathione peroxidase (GSH-px) activity was determined by the loss of reduced added to the supernatant and expressed as µmol GSH oxidized per minute (Flohe and Güzlei, 1984). The catalase (CAT) activity was measured using the method of Beers and Sizer (1952) and the glutathione (GSH) content was determined using Ellman’s method (1959). The tissue level of malondialdehyde (MDA) was measured using a modification (Zsoldos et al., 1983) of the original method described by Fong et al. (1973). The protein content was assayed by the method described by Lowry et al. (1951). The biochemical results were expressed in accordance to 1.0-mg protein (means ± SEM).

These parameters were measured from the gastric mucosal tissues (and not from the sera). Furthermore, these studies were carried out in an acid-dependent (HCl) and nonacid-dependent (ETOH) ulcer model in rats. Additionally we applied to prevent the gastric mucosal damage an endogenous compound (PGI2) (which has no scavenger property) and a scavenger compound (β-carotene). The main results of these observations are summarized briefly in the forthcoming sections.

8.11.1. Relationships between the changes in parameters of oxygen free radical systems versus cellular energy systems in the gastric mucosa of rats treated by intragastrically given HCl and ETOH

The observations were carried out in the morning. The gastric lesions were produced by intragastric administration of 1 mL of 96% ethanol or 1 mL of 0.6 M HCl. The animals were sacrificed at 0, 1, 5, 15, 30 and 60 minutes after giving the necrotizing agents.

The number and severity, parameters of the oxygen free radicals and the biochemical constituents of cellular energy systems were measured from the gastric fundic mucosa (the details of these measurements).

It is important to note that all measurements were carried out from the same tissue samples.

The detailed results are expressed in case of changes in the gastric fundic mucosa of rats, after the application of necrotizing agents on time sequence (Mózsik7et al., 1991 a).

Figure 244.

Changes in the severity of gastric mucosal damage of rats, produced by intragastrically applied ethanol (ETOH) and HCl, dependent on time after administration of necrotizing agents. [Mózsik, Sütő, Garamszegi, Jávor, Nagy, Vincze, Zsoldos: Eur. J. Gastroenterol. Hepatol. 3: 757–761, 1991 (with kind permission).]

Figure 245.

Changes in the catalase activity in the gastric fundic mucosa of rats, during the development of gastric mucosal damage produced by intragastrically applied ethanol or HCl, dependent on time after administration of necrotizing agents (100 = 0.60 Bergmeyer unit/mg protein). [Mózsik, Sütő, Garamszegi, Jávor, Nagy, Vincze, Zsoldos: Eur. J. Gastroenterol. Hepatol. 3: 757–761, 1991 (with kind permission).]

Figure 246.

Changes in the glutathione peroxidase (GSH-px) activity in the gastric fundic mucosa of rats, during the development of gastric mucosal damage produced by intragastrically applied ethanol or HCl, dependent on time after administration of necrotizing agents (100 = 0.60 Bergmeyer unit/mg protein). [Mózsik, Sütő, Garamszegi, Jávor, Nagy, Vincze, Zsoldos: Eur. J. Gastroenterol. Hepatol. 3: 757–761, 1991 (with kind permission).]

Figure 247.

Changes in the tissue contents of reduced glutathione (GSH) from the gastric fundic mucosa of rats, during the development of gastric mucosal damage produced by intragastrically applied ethanol or HCl, dependent on time after administration of necrotizing agents (100 = 0.60 Bergmeyer unit/mg protein). [Mózsik, Sütő, Garamszegi, Jávor, Nagy, Vincze, Zsoldos: Eur. J. Gastroenterol. Hepatol. 3: 757–761, 1991 (with kind permission).]

Figure 248.

Changes in the superoxide dismutase (SOD) activity in the gastric fundic mucosa of rats, during the development of gastric mucosal damage produced by intragastrically applied ethanol or HCl, dependent on time after administration of necrotizing agents (100% = 20.0 U/mg protein). [Mózsik, Sütő, Garamszegi, Jávor, Nagy, Vincze, Zsoldos: Eur. J. Gastroenterol. Hepatol. 3: 757–761, 1991 (with kind permission)].

Figure 249.

Changes in the tissue content of malondialdehyde (MDA) in the rat gastric fundic mucosa, during the development of gastric mucosal damage produced by intragastrically applied ethanol and HCl, dependent on time after administration of necrotizing agents (100% = 0.316 optical density/mg protein). [Mózsik, Sütő, Garamszegi, Jávor, Nagy, Vincze, Zsoldos: Eur. J. Gastroenterol. Hepatol. 3: 757–761, 1991 (with kind permission)].

Figure 250.

Summary of the changes in oxygen free radicals (catalase; glutathione peroxidase, GSH; reduced glutathione, GSH; superoxide dismutase, SOD and malondialdehyde, MDA) in the gastric fundic mucosa of rats treated with ethanol or HCl during the development of gastric mucosal damage dependent on time after administration of necrotizing agents. [Mózsik, Sütő, Garamszegi, Jávor, Nagy, Vincze, Zsoldos: Eur. J. Gastroenterol. Hepatol. 3: 757–761, 1991 (with kind permission).]

Figure 251.

Summary of the changes in the biochemical parameters of cellular energy systems in the rat gastric fundic mucosa after intragastrically applied ethanol and HCl, dependent on time after administration of necrotizing agents (details are presented earlier). [Mózsik, Figler, Garamszegi, Jávor, Nagy, Sütő, Tárnok, Zsoldos, 1987c (with kind permission).]

The critical analyses of these results allowed us to conclude that:

  1. The different changes in the experimentally measurable parameters (SOD, GSH-px, GSH, CAT and MDA) are present in gastric fundic mucosa of rats during the development of gastric mucosal damage produced by necrotizing agents, ETOH and HCl), however, these are not in a time-dependent manner;

  2. The changes in the oxygen free radicals differ in the gastric fundic mucosa of rats treated with intragastrically applied necrotizing agents during the development of gastric mucosal damage, depending upon the extent of gastric mucosal damage and time after administration of necrotizing agents;

  3. The measurable parameters of cellular energy systems are also detectable in the rat gastric fundic mucosa during the development of gastric mucosal damage produced by ETOH and HCl, dependent on time after necrotizing agents;

  4. The changes in the parameters of cellular energy systems indicate in the same directions, however, there are differ from each other, on dependence of time after administration of necrotizing agents;

  5. No close (which mathematically can be proven) the existing correlations are present in changes on experimentally measurable parameters of oxygen free radicals and of cellular energy systems in the gastric fundic mucosa of rats, treated by intragastrically applied ethanol and HCl on dependence severity (number) of gastric mucosa and on dependence of time after administrations of necrotizing agents (Mózsik et al., 1987c; Szabó et al., 2014).

8.10.2. Correlations between the oxygen free radicals and cellular energy systems in the gastric fundic mucosa of rats, during the development of gastric mucosal protection by prostacyclin (PGI2) and β-carotene, on dependence of applied doses of protecting compounds, extent of mucosal protective effects and time after administration of EtOH and HCl

These observations were carried out in the gastric fundic mucosa of rats during the development of gastric mucosal protection produced by PGI2 and β-carotene in which the gastric mucosal damage induced by intragastrically applied 1 mL of 0.6 M HCl and 1.0 of 96% EtOH in 1-hour observations. The results are presented in the forthcoming schematic summaries of Figures 252–255.

Figure 252.

Summary of the changes in the parameters of cellular energy systems from the gastric fundic mucosa during the development of gastric mucosal protection of PGI2 in rats, in which the gastric mucosal damage was produced by intragastric application of 1 mL of 0.6 M HCl (HCl model), depending upon the extents of mucosal protection, doses of PGI2 dependent on time after administration of necrotizing and protecting agents. (Note that the PGI2 was given 30 minutes before the HCl.) [(Mózsik, Garamszegi, Jávor, Sütő, Vincze, Tóth, Zsoldos: Mechanisms of gastric mucosal protection. In: Tsuchiya et al., 1988, Free Radical in Digestive Diseases. Elsevier Science Publishers, pp. 111–116 (with kind permission).]

Figure 253.

Summary of the changes in the parameters of oxygen free radicals in the gastric fundic mucosa during the development of gastric mucosal protection of PGI2 in rats, in which the gastric mucosal damage was produced by intragastric application of 1 mL of 0.6 M HCl (HCl model), depending on the extents of mucosal protection, doses of PGI2 and dependent on the time after administration of necrotizing and protecting agents. (Note that the PGI2 was given 30 minutes before the HCl.) [Mózsik, Garamszegi, Jávor, Sütő, Vincze, Tóth, Zsoldos: Mechanisms of gastric mucosal protection. In: Tsuchiya et al., 1988, Free Radical in Digestive Diseases. Elsevier Science Publishers, pp. 111–116 (with kind permission).]

Figure 254.

Summary of the changes in the parameters of cellular energy systems in the gastric fundic mucosa during the development of gastric mucosal protection of β-carotene in rats, in which the gastric mucosal damage was produced by intragastric application of 1 mL of 0.6 M HCl (HCl model), depending on the extents of mucosal protection, doses of PGI2 and dependent on the time after administration of necrotizing and protecting agents. (Note that the PGI2 was given 30 minutes before the HCl.) [Mózsik, Garamszegi, Jávor, Sütő, Vincze, Tóth, Zsoldos: Mechanisms of gastric mucosal protection. In: Tsuchiya et al., 1988, Free Radical in Digestive Diseases. Elsevier Science Publishers, pp. 111–116 (with kind permission).]

Figure 255.

Summary of the changes in the parameters of oxygen free radicals in the gastric fundic mucosa during the development of gastric mucosal protection of β-carotene in rats, in which the gastric mucosal damage was produced by intragastric application of 1 mL of 0.6 M HCl (HCl model), depending on the extents of mucosal protection, doses of β-carotene dependent on the time after administration of necrotizing and protecting agents. (Note that the PGI2 was given 30 minutes before the HCl.) [Mózsik, Garamszegi, Jávor, Sütő, Vincze, Tóth, Zsoldos: Mechanisms of gastric mucosal protection. In: Tsuchiya et al., 1988, Free Radical in Digestive Diseases. Elsevier Science Publishers, pp. 111–116 (with kind permission).]

Similar observations were carried out with the oxygen free radicals and cellular energy systems in the gastric fundic mucosa of rats, during the development of gastric mucosal protection of PGI2 and β-carotene in rats, in which the gastric mucosal damage was produced by 1 mL of 96% ethanol given intragastrically in 1-hour time period. PGI2 and β-carotene were applied 30 minutes before the application of ETOH.

The results and correlations between the results in these experimental parameters were in ETOH model the same as those in HCl model with PGI2 and β-carotene (these results are not presented in figures).

The following conclusions have been made from these observations:

  1. The parameters of oxygen free radicals are involved in the gastric mucosa during the development of gastric mucosal-preventive effects of PGI2 and β-carotene both in the HCl- and ETOH models in rats; however, there were no correlations depending on the doses of preventive drugs and on time after the application of necrotizing agents;

  2. The changes in the parameters of cellular energy systems in the gastric fundic mucosa in HCl- and ETOH models, during the development of gastric mucosal-protective effects, are dose-dependent in the case of both PGI2 and β-carotene depending on the extent of their mucosal-protective effects related to their characteristic to times of their different appearances, after the application of necrotizing agents;

  3. The changes in both the parameters of oxygen free radicals and cellular energy systems from the rat gastric fundic mucosa, during the development of gastric mucosal damage – produced by HCl and ETOH – and the development of gastric mucosal prevention by PGI2 and β-carotene, are to be present; however, dose–response correlations are presented only in case of parameters of cellular energy systems versus development of mucosal damage and its prevention (in both HCl and ETOH models);

  4. The changes in the parameters in oxygen free radicals and in cellular energy systems do not indicate close correlations in the gastric fundic mucosa of rats, during the development of mucosal damage produced by the intragastric administration of 1 mL of 0.6 M HCl or 1 mL of 96% ethanol and of mucosal-protective effects of PGI2 and β-carotene in these models, depending on time after the administration of necrotizing agents and on different doses of mucosal-protective agents;

  5. PGI2 is a physiological regulatory component but not a scavenger in living bodies, while β-carotene is one of the typical scavengers; however, both of them are able to produce practically the same changes in the parameters of oxygen free radicals and in cellular energy systems in association with the gastric mucosal-protective effects on gastric mucosal damage produced by HCl and ETOH, suggesting that the changes run besides each other both in the development of gastric mucosal damage and its prevention.

8.12. Comparative cellular molecular pharmacology of development of gastric acid secretion in ethanol-induced gastric mucosal damage and in PGI2-induced gastric mucosal prevention

Various drug actions and cellular mechanisms were demonstrated in the gastric fundic mucosa (especially in animal experiments). The changes of the cellular energy systems in the gastric fundic mucosa – in different animal models – suggested that “active metabolic adaptation” exists in the gastric tissues against the different ulcerogenic agents during the development of gastric mucosal damage.

There was no doubt that the prostacyclin also enhances mucosal biochemistry (including the cellular energy systems), when it was given to protect the gastric mucosal damage in rats. It is also clear that the gastric acid secretion is a consequence of an active metabolic process (involving the cellular energy systems).

In this chapter, the effects of different drugs having different subcellular mechanisms were studied in the following experimental models:

  1. In gastric acid secretion of 4-hour pylorus-ligated rats;

  2. In the development of gastric mucosal damage (number and severity) produced by 1 mL of 96% ethanol intragastrically applied in 1 hour; and

  3. In the gastric mucosal prevention (number and severity) of prostacyclin (PGI2; 5 µg/kg s.c. given at 30 minutes before the administration of 1 mL of 96% ethanol) as in point 2;

The inhibitory effects of different drugs having different subcellular mechanisms were observed in different experiments, and thereafter their affinity and intrinsic activity curves were calculated according to the methods of Csáky (1969). The value of atropine was taken to be equal to 1.0 in calculation of intrinsic activity (αatropine = 1.0).

The following drugs were used in these observations: atropine, actinomycin D, cimetidine, epinephrine, histamine, mannomustine, pentagastrin, PGI2, ouabain and tetracycline (Table 43).

Drugs Subcellular mechanisms
Atropine Decrease of ATP transformation into ADP by
membrane ATPase,
Small increase of ATP transformation by adenylate
Cyclase
Actinomycin D Inhibition of RNA synthesis depending on DNA
Cimetidine Inhibition of ATP-cAMP transformation by adenylate cyclase
Dinitrophenol Inhibition of oxidative phosphorylation
Epinephrine Decrease of ATPtransformation into ADP by
membrane ATPase
Increase of ATP-cAMP transformation by adenylate cyclase
Histamine Increase of ATP-cAMP transformation by adenylate
cyclase
Decrease of ATP-ADP transformation by membrane ATPase
Mannomustine Inhibition of de novo synthesis of DNA
Pentagastrin Increase of ATP-cAMp transformation by adenylate
cyclase
Decrease of ATP transformation into ADP by membrane ATPase
PGI2 Increase of ATP-cAMP transformation by adenylate
cyclase
Decrease of ATP-ADP transformation by membrane ATPase
Ouabain Inhibition of ATP transformation by membrane ATPase
Tetacycline Inhibition of protein translation

Table 43.

Subcellular mechanisms of drugs used in the experiments. For detailed references for drug actions, see Mózsik and Jávor: Dig. Dis. Sci. 33:92–105, 1988 (with kind permission).

8.12.1. Affinity and intrinsic activity curves for drugs inhibition the gastric acid secretion in 4 hours pylorus ligated rats

Figure 256.

Affinity curves for the drugs inhibiting the gastric acid secretion in 4-hour pylorus-ligated rats. [Mózsik and Jávor: Dig. Dis. Sci. 33:92–105, 1988 (with kind permission).]

Figure 257.

Intrinsic activity curves for the drugs inhibiting gastric acid secretion in 4-hour pylorus-ligated rats. [Mózsik and Jávor: Dig. Dis. Sci. 33:92–105, 1988 (with kind permission).] The values of pD2 (dose necessary to produce 50% inhibition in the affinity curves) and of pA2 (dose necessary to produce 50% inhibition in the intrinsic activity curves) were calculated from the affinity and intrinsic activity curves (Table 44).

Drugs pD2 α pA2
Atropine 5.75 1.00 5.80
Actinomycin D 5.63 0.87 5.86
Cimetidine 3.00 0.64 3.20
Mannomustine(Degranol) 4.25 0.78 4.90
Dinitrophenol 3.50 0.56 3.75
Epinephrine 4.95 0.80 4.75
PGI2 0.00 0.00 0.00
Oaubain 4.75 0.80 4.50
Tetracycline 3.63 0.78 3.75

Table 44.

Values of affinities (pD2) and intrinsic acivities (α atropine = 1.00 and pA2) for drugs inhibiting the gastric acid secretion in 4-hour pylorus-ligated rats. Values are in [−] molar. [Mózsik and Jávor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

8.12.2. Affinity curves for the drugs inhibiting the development of ethanol-induced gastric mucosal damage in rats

Figure 258.

Affinity curves for the drugs inhibiting the development of gastric mucosal damage produced by ethanol administration in rat. [Mózsik and Jávor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

Figure 259.

Intrinsic activity curves for the drugs inhibiting the development of gastric mucosal damage produced by ethanol administration in rats. [Mózsik and Jávor: Dig. Dis. Sci. 33: 92–105, 1988 (with kind permission).]

8.12.3. Affinity and intrinsic activity curves for the drugs inhibiting the PGI2-induced gastric mucosal prevention on the gastric mucosal damage produced by ethanol in rats

Figure 260.

Affinity curves for the drugs inhibiting the PGI2-induced gastric mucosal protection of the ethanol-produced gastric mucosal damage in rats.

Figure 261.

Intrinsic activity curves for the drugs inhibiting the PGI2-induced gastric mucosal protection of the ethanol-produced gastric mucosal damage in rats.

8.11.4. Short discussion of results obtained from the observations presented in Sections 8.14.1–8.14.3

There were different unexpected results, when we practically noted that the examined drugs (with different subcellular mechanisms) were able to produce very similar actions on the inhibition of gastric acid secretion, ethanol-induced mucosal damage and PGI2-induced gastric mucosal protection in the ethanol-produced gastric mucosal damage in rats (Figure 262).

The histamine, pentagastrin and dinitrophenol enhanced the PGI2-induced gastric mucosal protection, and histamine and pentagastrin stimulated the gastric acid secretion in 4-hour pylorus-ligated rats. The contrary action of dinitrophenol (namely its inhibition of gastric acid secretion and its stimulation of the PGI2-induced gastric mucosal protection) can be explained by the significant time difference of the experiments.

When the values of pD2 and pA2 were calculated, these values were practically in all of three different experimental models.

The same drugs were used to study the subcellular mechanisms of damage to the gastric mucosa by ethanol. Pentagastrin and histamine, while stimulating acid secretion, were able to reduce gastric mucosal damage due to ethanol. The effects of all drugs on both acid secretion and mucosal protection were dose-dependent. Furthermore, the molarities were similar in both types of experiments.

The following can be concluded:

  1. The same subcellular mechanisms are involved in acid secretion and mucosal protection;

  2. Active metabolic processes are involved in both;

  3. Significant changes in membrane-bound ATP-dependent energy systems, oxidative phosphorylation, DNA and RNA synthesis, and de novo protein synthesis in both;

  4. Ethanol-induced gastric mucosal injury can be prevented by drugs which inhibit active metabolism or those which increase active metabolic responses (histamine, pentagastrin);

  5. No significant difference in effective doses on gastric acid secretion or protection against ethanol-induced mucosal injury was seen between drugs having different mechanisms of subcellular action;

  6. The same subcellular mechanisms are involved in the PGI2-induced gastric mucosal protection in ethanol-model.

Figure 262.

Schematic summary of the effects of different drugs having different subcellular mechanisms on the gastric acid secretion, development of ethanol-induced gastric mucosal damage and PGI2-induced gastric mucosal protection in the ethanol-produced gastric mucosal damage in rats.

8.13. Epinephrine-model

As demonstrated earlier, epinephrine, given immediately after pylorus ligation, inhibited the gastric acid secretion and ulcer development (Nagy et al., 1976; Sethbakdi et al., 1970 a, b; Pfeiffer, 1971; Pfeiffer and Sethbakdi, 1971; Pfeiffer and Mózsik, 1990) (Figure 263).

Figure 263.

The schematic representation of the different ulcer provocations in pylorus-ligated rats and in epinephrine model. [Nagy, Mózsik, Tárnok, Jávor (1979) Drugs Exp. Clin. Res. 5, 87–96 (with kind permission).]

Sethbakdi et al. (1970 a, b) elaborated a new experimental model, “epinephrine model,” in which the gastric ulceration appeared in the glandular stomach. Sethbakdi et al. (1970 a, b) applied epinephrine at 4 hours after pylorus ligation and the animals were sacrificed at 5 hours after the pylorus ligation. The biochemical analysis of this epinephrine model led to a new possibility to understand the mechanisms of this model (especially membrane-bound energy systems) (Mózsik and Pfeiffer, 1992).

Figure 263 indicates the time correlation between the 24-hour pylorus-ligated rats versus epinephrine model. Sethbakdi et al. found that the optimal dose of epinephrine is 0.4 mg/kg given at 4 hours after pylorus ligation, whereas the animals were sacrificed at 5 hours after pylorus ligation (that is 1 hour after the epinephrine application) (Nagy et al., 1976; 1981a; Mózsik, 1971) (Figure 264).

When we applied different doses (0.1, 0.4 and 1.0 mg/kg), the H+ concentration, H+ output and volume of gastric secretion dose-dependently decreased (Figure 263).

The peak of gastric mucosal injury was found after the application of 0.4 mg/kg, when different doses of epinephrine were given at 4 hours; however, the ulceration was smaller when epinephrine was given at a dose of 0.1 or 1.0 mg/kg (Figures 264, 265).

When the effect of epinephrine (given at the time of pylorus ligation) was studied (applied in a dose of 0.4 mg/kg), the tissue level of cAMP was significantly higher only in the pylorus-ligated rats; however, when epinephrine (in doses of 0.1, 0.4 and 1.0 mg/kg) was given at 4 hours after pylorus ligation, we could not notice any increase in the tissue level of cAMP (Mózsik and Pfeiffer, 1992) (Figures 267, 268). In other words, the different doses of epinephrine were not able to produce an elevation in the tissue cAMP. Therefore, cAMP-induced gastric mucosal-protective effects completely disappeared in 4-hour pylorus-ligated rats.

Figure 264.

Dose–response curves for epinephrine on the gastric secretory responses (volumes H+ output and H+ concentration) in 5-hour pylorus-ligated rats, when the different doses of epinephrine were given at 4 hours after pylorus ligation. The animals were sacrificed one hour later (means ± SEM). [Nagy, Mózsik, Tárnok, Jávor (1979), Drugs Exp. Clin. Res. 5, 87–96 (with kind permission).]

Figure 265.

The extent of gastric ulcer provocation by epinephrine in 5-hour pylorus-ligated rats when the different doses of epinephrine were i.p. at 4 hours after pylorus ligation. The right side of the figure indicates epinephrine effect on the same parameters given at a dose of 0.4 mg/kg immediately after pylorus ligation (means ± SEM). [Nagy, Mózsik, Tárnok, Jávor (1979). Drugs Exp. Clin. Res. 5, 87–96 (with kind permission).]

Figure 266.

Changes in the tissue level of cAMP in pylorus-ligated rats when epinephrine (given at a dose of 0.4 mg/kg) was given immediately after pylorus ligation (E) and in different doses at 4 hours after pylorus ligation. The animals were sacrificed at 5 hours after pylorus ligation (means ± SEM). [Mózsik et al. (1981g). Acta Medica Acad. Sci. Hung. 36: 1–29 (with kind permission).]

Figure 267.

The epinephrine (E) induced changes in the rat gastric fundic mucosal levels of cAMP depending upon the time and doses (means ± SEM). [Mózsik et al. (1981g). Acta Medica Acad. Sci. Hung. 36: 1–29 (with kind permission).] For further explanation, see Figure 263.

8.14. Drug actions depend on the stomach cellular energy systems in dependence of different functional states of target organ

The Δ changes in the gastric fundic mucosal ATP, ADP, AMP and cAMP were detected by the application of different doses of epinephrine (0.1, 0.4 and 1.0 mg/kg) given in intact, 1 hour and 4 hours pylorus-ligated rats (Figures 268–271). These values differed significantly from each other. The largest action was obtained in intact animals, smaller in 1 hour and less values in 4-hour pylorus-ligated rats. These results together clearly indicate that the drug actions depend on the actual functional state of the target organ.

Figure 268.

Δ changes in the epinephrine-induced gastric mucosal levels of ATP depending upon different functional activities of the rat gastric fundic mucosa (means ± SEM). [Mózsik and Pfeiffer, Exp. Clin. Gastroenterol 2, 190–194, 1992 (with kind permission).]

The results of observations presented in Sections 8.15 and 8.16 clearly indicate that the drug (epinephrine) effects significantly differ depending on different functional states of the target organ (presently, of stomach). Furthermore, the differences in the drug actions on the stomach – depending on the differences of its functional state – show dose-dependent actions.

In everyday medical practice, the clinicians never know exactly the etiology of peptic ulcer, when patients are diagnosed with the existence of the disease. These different conditions of the functional states of GI tract surely involved in the final efficiency of the medical treatments in patients with GI disorders as well as pathogenic roles of different noxious agents.

Figure 269.

Δ changes in epinephrine-induced gastric mucosal level of ADP depending on different functional activities of the rat gastric fundic mucosa (means ± SEM). [Mózsik and Pfeiffer, Exp. Clin. Gastroenterol 2, 190–194, 1992 (with kind permission).] For further explanation, see Figure 263.

Figure 270.

Δ changes in epinephrine-induced gastric mucosal levels of AMP depending upon different functional activities of the rat gastric fundic mucosa (means ± SEM). (Mózsik and Pfeiffer, Exp. Clin. Gastroenterol 2, 190–194, 1992). For further explanation, see Figure 263.

Figure 271.

Δ changes in the epinephrine-induced gastric mucosal levels of cAMP depending upon different functional activities of the rat gastric fundic mucosa (means ± SEM). [Mózsik and Pfeiffer, Exp. Clin. Gastroenterol 2, 190–194, 1992 (with kind permission).] For further explanation, see Figure 263.

8.14. Surgical vagotomy and atropine-, cimetidine-, PGI2- and ß-carotene-induced gastric mucosal damage in ETOH-model

There was no doubt after the works of Robert et al. (1979) that the small dose of PGI2 (5 μg/kg) is able to prevent the chemically induced gastric mucosal damage.

Figure 272 clearly demonstrates that the ETOH-induced gastric mucosal damage was enhanced after bilateral surgical vagotomy. (Jávor et al., 1981; Mózsik et al., 1981a).

This observation was the first evidence to suggest that the intact vagal nerve is necessary not only in the aggression but also in the defense in the stomach (Jávor et al., 1981a; Mózsik et al., 1992 ; ütő et al.,;1989, 1992; Vincze et al.; 1992; 1993 a 1997; Király et al.,; 992 a b).

After bilateral surgical vagotomy, the gastric mucosal-protective effects of atropine (Figure 273), cimetidine (Figure 274) β-carotene (Figure 275) and PGI2 (Figure 276) were not present.

Miller et al. (1983) published an excellent review paper on the PGs, which indicated that the gastric mucosal effect of PGs disappear after surgical vagotomy. In other papers written by his team (1983), our original observations were mentioned; however, those were completely forgotten later on in the literature (Henagan et al., 1983; Forte and Lee, 1977).

Figure 272.

The ethanol-induced gastric fundic mucosal lesions (number and severity) with and without bilateral surgical vagotomy (means ± SEM). [Mózsik et al., Life Sciences 49, 1383–1388, 1991 (with kind permission).]

Figure 273.

The atropine (given in cytoprotective and antisecretory doses)-induced gastric mucosal-preventive effects with intact vagal nerve, which disappeared completely after bilateral surgical vagotomy in ETOH model (means ± SEM). [Mózsik et al., Life Sciences 49, 1383–1388, 1991 (with kind permission).]

Figure 274.

The cimetidine (given in cytoprotective and antisecretory doses)-induced gastric mucosal-preventive effects on the number and severity in the rat gastric fundic mucosa with intact vagal nerve and after bilateral surgical vagotomy (means ± SEM). [Mózsik et al., Life Sciences 49, 1383–1388, 1991 (with kind permission).]

Figure 275.

The β-carotene (given at doses of 1 mg and 10 mg/kg doses)-induced gastric mucosal-preventive effects on the number and severity in rats with intact vagal nerve and after bilateral surgical vagotomy in ETOH model (means ± SEM). [Mózsik et al., Life Sciences 49, 1383–1388, 1991 (with kind permission).]

Figure 276.

The PGI2 (given at doses of 5, 50 and 100 μg/kg i.g.)-induced gastric mucosal-protective effect on the number in the rat gastric fundic mucosa treated with ETOH – in intact vagal nerve and after bilateral surgical vagotomy (means ± SEM). [Mózsik et al., Life Sciences 49, 1383–1388, 1991 (with kind permission).]

8.16. Gastric mucosal protective effects of ß-carotene and adrenals

Previously, β-carotene was used as a scavenger material. When the surgical vagotomy was able to neglegee β-carotene-induced gastric mucosal-preventive effect, we suggested that the intact adrenals are also important key factors for the development of its gastric mucosal-protective effects (Szabo et al., 1983; Sütő et al., 1989; Vincze et al., 1997).

No gastric mucosal-preventive effects of β-carotene were observed after the surgical removal of adrenals. When supplementation with glucocorticoid was performed, the gastric mucosal effects of β-carotene resumed. When supplementation with mineralocorticoid was performed, the gastric mucosal-protective effects of β-carotene did not appear.

This was another interesting observation, because the scavenger agent cannot act in rats without adrenals (Mózsik et al., 2001a).

8.16. Surgical vagotomy and tissue levels of PGE2 and PGI2

After surgical vagotomy, both PGE2 and PGI2 (6-keto-PGF-1α) significantly decreased (Sütő et al., 1992) (Figure 277).

The gastric mucosal-protective effect of β-carotene was dose-dependent; however, a significant difference was obtained between the effects (number) registered in animals with intact vagal nerve versus post bilateral surgical vagotomy (Figure 278).

Figure 277.

Surgical vagotomy-induced changes in ethanol-induced gastric mucosal damage without (untreated, sham-operated rats) and with surgical vagotomy (a) changes in levels of PGI2, (b) 6-keto-PGF (as the final product of) and (c) in the gastric mucosa (means ± SEM). [Sütő et al., Acta Physiol Hung 80, 205–211, 1992 (with kind permission).]

Figure 278.

Dose–response curves for β-carotene in gastric mucosal damage (number) in rats treated with ETOH in animals with intact vagal nerve and after bilateral surgical vagotomy (means ± SEM). [Sütő et al., Acta Physiol Hung 85, 207–213, 1993 (with kind permission).]

8.17. Biochemical changes in the gastrointestinal tract and oxygen free radicals, scavengers in of intact vagal nerve, “surgical” and “chemical” vagotomy, intact adrenals, after adrenelectomy and supplemention of glucocorticoid and mineralocorticoid

There is no doubt that significant changes can be obtained in the oxygen free radicals during the development of the gastrointestinal mucosal damage (Mózsik et al., 1984 a, b, c). However, we expected the gastric mucosal-protective effects of retinoids in rats after surgical vagotomy (Jávor et al., 1983; Mózsik et al., 1988; Mózsik et al, 1991a; Mózsik and Jávor, 1991). Surprisingly, the gastric mucosal-protective effects of retinoids completely disappeared after bilateral surgical vagotomy (Mózsik et al., 1991a; Sütő et al., 1992). It was suggested that the presence of the intact vagal nerve and adrenals is necessary for the development of gastric mucosal-preventive effects of scavengers in animal observations.

Written By

Gyula Mozsik and Imre Szabó

Submitted: March 6th, 2015 Published: March 9th, 2016