Perspective Chapter: Stimulation and Activation of the Pituitary Gland

Abstract

The pituitary gland no larger than a pea in shape is located at the base of the brain and is called the “master” gland of the endocrine system because it controls the functions of many other endocrine glands including thyroid, parathyroid, pancreas, reproductive, and adrenal gland. The pituitary gland is attached to the hypothalamus (a part of the brain that affects the pituitary gland) by nerve fibers and blood vessels. The pituitary gland regulates the hormones that have to do with growth, digestion, protein absorption, use, and controlling blood pressure. Overactivity and underactivity of this pea-sized gland on the skull base of the brain can cause a various range of disorders. Since pituitary gland and hypothalamus work together so closely that if one of them is damaged, it can affect the hormonal function of the other. Endocrinologists treat the issues related to the abnormal functioning of this gland by therapeutic interventions. Now-a–days, the concept of mindfulness is widely accepted to treat endocrine disorders. Psychoneuroendocrinology is the new upcoming branch in therapeutics of several neuroendocrine diseases. The pituitary gland disorders can also be corrected by lifestyle modifications like practicing certain yoga asanas, pranayama, and meditations.

1. Introduction: the pituitary gland

A small pea-shaped pituitary gland is referred to as the body’s master gland as it controls many vital body functions via controlling the activity of most other hormone-secreting glands including thyroid, parathyroid, pancreas, reproductive, and adrenal gland. It plays a major role in regulating vital body functions and general well-being.

Anatomically, the pituitary gland is like a protrusion at the base of the brain and the size of this is a pea or cherry. The gland is located in a well-protected small bony cavity sella turcica of the skull, level with the eyes, and roughly in the middle of the head.

It is attached to the hypothalamus of the brain which controls the involuntary (vegetative) nervous system. This part of nervous system helps in managing the activities like balance of energy, heat and water including body temperature, heartbeat, urination, sleep, hunger, and thirst. The gland also produces several hormones which regulate most of the hormone-producing glands in the body or have a direct effect on the target organs especially thyroid, reproductive organs, adrenal gland etc. [1,  2]. This hormone secretion generates inhibitory or stimulatory signals from the hypothalamus.

The pituitary gland can be divided into two lobes: Anterior pituitary lobe and Posterior pituitary lobe.

1.1 Anterior pituitary lobe

It is made of several different types of cells which produce and releases the following different types of hormones:

1. Growth hormone (GH): This hormone regulates growth and physical development. Primary targets of this hormone are bone and muscles. It can also stimulate growth in almost all tissues of the body.

2. Thyroid-stimulating hormone (TSH): This thyroid-stimulating hormone which activates the thyroid to release the thyroid hormones are very crucial in controlling the overall metabolism.

3. Adrenocorticotropic hormone (ACTH): This hormone stimulates the adrenal gland for the production of cortisol and other hormones.

4. Follicle-stimulating hormones: This hormone is involved in the secretion of estrogen and the growth of ovum in women and sperm cell production in men.

5. Luteinizing hormone (LH):This hormone is involved in the production of the sex hormones like estrogen in women and testosterone in men.

6. Prolactin helps in the production of milk in breastfeeding women.

7. Endorphins have pain-relieving properties and are thought to be connected to the pleasure centers of the brain.

8. Enkephalins are closely related to endorphins and also have pain-relieving effects.

9. Beta-melanocyte-stimulating hormone: This hormone stimulates increased pigmentation in response to exposure to UV radiation.

1.2 Posterior pituitary lobe

This section of the pituitary gland also secretes hormones—vasopressin and oxytocin. These hormones are usually produced in the hypothalamus and stored in the posterior lobe till they are released.

Vasopressin: This hormone is also called as antidiuretic hormone. It helps body in water conservation and prevents dehydration.

Oxytocin: This hormone stimulates the release of breast milk and helps in contractions of uterus during labor [1, 2].

The disorders of the pituitary gland are pituitary tumors, hypopituitarism, Cushing’s syndrome, acromegaly, hyperprolactinemia, and diabetes insipidus and disorder due to traumatic injury to the brain.

Following are the common symptoms seen in the disorders of the pituitary gland: headaches, generalized weakness or fatigue, unexplained weight gain, high blood pressure, insomnia, mood swings, psychological state changes, depression, memory loss, reproductive issues like infertility, erectile dysfunctions and irregular menses, excessive or unusual hair growth, and lactation is found when the individual is not nursing.

2. Hypothalamus pituitary axis

The three components, the hypothalamus, the pituitary gland, and the adrenal glands comprise the HPA axis or HPTA axis. This HPA axis represents a complex set of direct influences and feedback interactions among them.

This HPA axis is a major neuroendocrine system that has control over the reactions to stress and other various major body processes like digestion, immunity, moods and emotions, sexuality, energy storage, and expenditure. It serves as a common mechanism for interactions among glands, hormones, and part of the midbrain [3, 4]. As steroid hormones are produced in the vertebrates, there is a direct link between the HPA axis and corticosteroids under stress.

The functioning of the HPA axis is affected by various factors including exposure to early life stress situations. These affect the brain’s endocrine system and will suppress the neuronal responses and immunity of an individual. Chronic stress leads to an increase in cortisol release. Too much cortisol release can sometimes lead to insomnia, weight gain, anxiety, and depression.

This will affect the quality of an individual’s behavior throughout the life. Treatment of such chronic life situations with drug therapy is routinely practiced by endocrinologists. In the long run, they show side effects.

Recently, alternative therapies are proven to be better in the treatment of the chronic diseases. These alternative therapies work on the holistic approach—they are noninvasive and are with less side effects.

3. Mind–body disease interactions

The studies in infant development and neuroscience are proving the modern developments in psychoanalytical theory to produce a coherent link between mind–body diseases. The studies reported that the infant’s failure to environmental responses leads to fragile vulnerable personality structure that relies on external objects to regulate psychobiological responses. These responses are mediated through the rostral limbic system and expressed through changes in the HPA axis and autonomic nervous system. The article written by John Mason (1968) concluded that as a perception of stressful situation, the novelty, unpredictability, high ego involvement, anticipation on negative consequences, and uncontrollability are the behaviors exhibited by an individual. The HPA axis regulates and controls the overall psychological and neurological behaviors of an individual.

4. Yoga and pituitary health

The Bhagwad Gita—quotes “Yoga is the Journey of the self Through the Self, To the Self.” In the Indian scriptures, yoga and yogic science have proven to be effective tools for the overall health and wellbeing of an individual.

“Yoga is a complete science of Ancient Indian system of Medicine which is more than 5000 years old whereas the present more prevalent system of allopathic medicine is nearly 200 years old only” [5].

As the body’s biochemistry starts changing from the age of 20 years, it is advised that practicing some yoga for at least half an hour everyday will keep the body’s biochemistry fit and help us to be healthy [6].

Yoga helps in the following ways to improve our health:

1. Improves flexibility

2. Helps build muscle strength

3. Helps in perfecting your posture

4. Reduces cartilage and joint breakdown

5. Protects your spine

6. Improves bone health

7. Increases blood circulation

8. Drains lymph and upsurges immunity

9. Increases heart rate

10. Reduces blood pressure

11. Regulates the adrenal gland function

12. Makes you feel happy

13. Gives you a healthy life style

14. Reduces blood sugar

15. Relaxes body systems

16. Increases focus and concentration

17. Maintains the nervous system

18. Releases the tension in limbs

19. Improves sleep quality

20. Increase self esteem

4.1 Yoga and pituitary health

Practicing yoga regularly helps us to achieve complete physical and mental health scientifically. Yoga is also emerging as a more effective way of nonpharmacological and noninvasive endocrine therapy against many diseases including the pituitary health. A complete physical and mental wellbeing state can only be achieved by following healthy lifestyles, healthy eating habits, maintaining physical fitness together with maintaining spiritual and emotional health. Yogic way of living helps to achieve optimum physical, mental, and spiritual health. Several studies have reported that yoga helps in achieving health through its influence on the endocrine system of our body. Endocrine system hormones are the primary messengers that are produced by several endocrine glands, i.e., hypothalamus, pituitary gland, adrenal glands, thyroid gland, parathyroid glands, pancreas, and gonads of the body. The exact meaning of the term “endocrine” means a process of specific stimuli causing the release of the hormones from the glands into the bloodstream. For a balanced hormonal function in all the changing environment, it is necessary that all the hormonal systems in the body function in a synchronous manner and regulate each other. Many releasing hormones are secreted by hypothalamus in the brain and are transmitted to the pituitary gland via blood circulation. The major role of these releasing hormones is induction and controlling of the secretion of the pituitary hormones which in turn are transported via blood to various target hormonal glands of the body. The feedback from these target glands to the hypothalamus and pituitary controls the further release and maintain the hormonal balance. These feedbacks cause a negative and or positive effect on hormone production.

5. The lifestyle modifications and pituitary gland

The hormonal change in both men and women significantly impacts the quality of life. It is found that the hormonal imbalance affects the cognitive function, i.e., ability to think or analyze. These also cause issues like bloating, headaches, sleep disturbances, eating disorders, weight gain, skin issues, and lowering immunity, and many more even on small changes in the hormonal imbalances. If not properly diagnosed at the early stages, this may lead to several chronic diseases [7].

A significant health challenge is the emergence of stress and stress-related diseases. According to the traditional definition of stress, it is the real or predicted disruption of homeostasis caused by particular physical and emotional occurrences known as “stressors.” A damaging, self-replicating cascade of neuroendocrine, metabolic, and cognitive abnormalities brought on by protracted exposure to stress can be crucial in the onset and development of cardiovascular disease (CVD), such as hypertension.

The HPA axis and the sympathoadrenal system (SAS), which consists of the sympathetic nervous system (SNS) and adrenomedullary system (AS), are the two components of complex stress system that mediates the body’s reactions to stressors. The main mediators of the stress response are the hormones of the HPA axis and the catecholamines generated by SAS.

The paraventricular nucleus of the hypothalamus, or PVN, is a key component in the stress response. The production of CRH and Arginine vasopressin (AVP), which starts the endocrine response to stressors, is caused by stress-induced activation of the parvocellular neurons of the PVN. The anterior pituitary gland’s ability to secrete ACTH is governed by CRH. In PVN parvocellular neurons, AVP colocalizes with CRH. AVP amplifies the result of in the anterior pituitary.

AVP increases the impact of CRH on ACTH release in the anterior pituitary. The noradrenergic neurons in the locus ceruleus (LC) and CRH neurons in the PVN have reciprocal connections, which causes them to stimulate one another in a positive feedback manner. The adrenocortical and autonomic branches of the stress response are connected by CRH, which functions as a neurotransmitter that mediates sympathetic arousal. The sympathetic nervous systems (SNS) stimulation in response to stress is regulated by the locus ceruleus-norepinephrine system (LNE). Glucocorticoid production from the adrenal cortex is primarily regulated by ACTH. The HPA axis, which regulates how an organism reacts to stimuli, is final affected by glucocorticoid chemicals, primarily cortisol in humans and cortisone in animals.

During the initial phase of the acute stress response, the SAS is engaged, resulting in the typical “fight-or-flight” behaviors. These are rapid but transient physiological adjustments made to get ready for the challenge posed by a stressful event. It is mediated by the release of catecholamine like norepinephrine (NE). The secondary phase involves a hormonal mechanism (HPA axis) that is thought to be slower than the synaptic mechanisms that activate the SAS, but which nonetheless causes an amplified and prolonged secretory response involving stress hormones like CRH, ACTH, and glucocorticoids (GCs), with cortisol being the main GC involved in humans (long-lasting response). Cortisol has an impact on the brain as well as other bodily components.

The body’s capacity to process stresses cognitively and physically is further hampered by stress-induced brain alterations. Multiple interconnected organ systems (autonomic, neuroendocrine, immune, and cardiovascular systems) involved in the stress response are negatively impacted by the prolonged and synergistic effects of stress hormones and pro-inflammatory cytokines in chronic stress, which ultimately leads to various pathological conditions [8].

There are several simple ways to take care of the pituitary gland and its functioning, which are as follows:

1. Wake up early in the morning

2. Eat proper and nutritious food,

3. Practice yoga and meditation to reduce stress

4. Get good quality sleep

5. Withdrawal from addictions like smoking tobacco and alcoholism

6. Take care about the consumption of food toxins and adulterants

7. Regular physical activity

8. Keep away from sugars and other food allergens

9. Add lots of fiber and good-quality protein in diet

10. Consume healthy fats.

Several studies have indicated that frequent yoga practice is linked to decreased basal cortisol and catecholamine release, decreased sympathetic activity, and increased parasympathetic activity. It is supposed to result from yoga’s ability to reduce stress. Yoga’s ability to reduce stress may be a result of modulating limbic signals, which, through the hypothalamus, can change sympathetic activity and the hormone response to stress. In addition to helping to reduce cortisol levels and alleviate stress, yoga may also increase hippocampus 5HT1A receptor activity [9, 10, 11].

Gamma-aminobutyric acid (GABA) mediates the amplitude and duration of the stress response and thus negatively regulates excitability in the PVN. This leads to direct inhibition of HPA axis. Yoga modulates this GABA-nergic stimulation of HPA axis. Regular yogic practices have shown to increase the GABA levels in the thalamus. This may be attributed to the ability of yoga practices to increase in the activity of parasympathetic nervous system [12, 13, 14, 15, 16, 17].

Yoga mediates downregulation of HPA axis and sympathoadrenal system, stimulation of vagus resulting in parasympathetic dominance, increase in baroreflex sensitivity, and increase in brain GABA levels inhibiting PVN integrating area of stress signals. Thus, mediates the beneficial effects on overall health of an individual.

6. Conclusion

This chapter mainly focuses on the alternative ways of stimulating and activating the pituitary gland and maintaining the hormonal balance in the body by alternative noninvasive ways of medicine like practicing yoga and adopting healthy lifestyle practices. Yogic intervention modifies neuro-endocrine modulation of the stress response and exerts its positive benefits via a number of distinct mechanisms. Yoga reduces the neuro-humoral reaction to stress. Proper mind–body interactions are very important in an individual to have a healthy life. Yogic practices help in achieving them. A contented and mindful life is the key for a healthy life in this modern technological /mechanical era.

Conflict of interest

The author declares she has no conflict of interest.