The zebrafish Danio rerio appears to be as an alternative experimental model mainly used on toxicological evaluations since the 1990s. In this chapter, we illustrate using a histopathological study the evaluation of a complex phytopreparation with janaguba milk (TPJM, used in popular medicine), which was administrated in zebrafish by immersion in water. We determined (1) lethal concentration 50 (LC50) – 1188.54 μg/mL; (2) the behavioral changes; and (3) the acute administration of TPJM modifications (48 h) at concentrations 500, 750, 1000, and 1500 μg/mL, on the histopathological parameters of the gills, kidneys, and liver. Also the concentrations of 1000 and 1500 μg/mL caused significant damage to the gill tissue and produced a high rate of histological changes in the liver. The kidneys showed greater changes at concentrations of 750, 1000, and 1500 μg/mL. Based on the percentage of TPJM extracts that was only 1.85%, the LC50 was calculated as 475 mg/kg; according to traditional indication, only 6 tablespoons/day is consumed; and it is possible to infer that only 0.5 g of active ingredient is ingested by an adult user per day, corresponding to a dose of 7.14 mg/kg, which is far from the toxic effects, demonstrating low toxicity of TPJM.
Part of the book: Histopathology
Zebrafish (Danio rerio) is a small-sized teleost fish natural of tropical regions, with a short life cycle and high homology toward humans. These features make zebrafish an attractive and promising model organism for nonclinical tests due to the ease of handling and cost–benefit compared to other models. The digestive, cardiovascular, urinary, nervous, and reproductive systems of zebrafish display feature similar to those of superior mammals, and due to its susceptible organs, the adult zebrafish has been used to test the toxicity of environmental compounds and potential drug candidates through histopathology analysis complementarily with other parameters. In such cases, the choice of the organ assessed relies on the type of compound tested, administration route, and biological activity. This chapter brings together histopathological nonclinical toxicity studies performed exclusively with zebrafish, highlighting significant histological changes found in its gills, liver, kidneys, and intestine. Based on the information presented here, it is expected that the researcher recognizes differences between healthy and changed tissue, without having to compare its result with other species.
Part of the book: Zebrafish in Biomedical Research