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The effect of stress on regulation and regeneration of glucocorticoids in animal models differing in response of hypothalamo-pituitary-adrenal axis
Vodička, Martin ; Pácha, Jiří (advisor) ; Svoboda, Jan (referee) ; Bendová, Zdeňka (referee)
Stress reaction is usually activated by the brain, when homeostasis is or perceived to be threatened. The stress signals are transmitted from the brain by two main branches; the sympathoadrenomedullary and the hypothalamo-pituitary-adrenal (HPA) axes and employ neural, humoral and immune pathways to cope with the stressor. Because of its potency, the stress reaction has to be precisely regulated. The HPA axis is regulated by feedback loops where its end product, corticosterone in laboratory rat and mouse, inhibits its activity. The effect of corticosterone does not depend only on the concentration of corticosterone but also on local metabolism of glucocorticoids via oxo-reduction catalyzed by the enzyme 11β -hydroxysteroid dehydrogenase 1 (encoded by the Hsd11b1 gene), which intracellularly regenerates active corticosterone from inactive 11-dehydrocorticosterone, or by extra-adrenal de novo steroidogenesis of glucocorticoids. We focused on analysis of stress response in experimental animals differing in HPA axis responsivity (Fischer 344 rats (F344) vs. Lewis rats (LEW) and germ-free (GF) vs. specific pathogen free mice (SPF)) with special emphasis on regulation of stress response, glucocorticoid regeneration and influence of gut microbiota. We found that stress modulated local regeneration of...
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Effects of hormonal treatment during artificial reproduction to produce to fingerlings of weatherfish (Misgurnus fossilis)
HOUDA, Ondřej
In this M. Sc. thesis, the influence of selected commercially available hormonal preparations based on hCG (Pregnyl, Chorulon) and GnRH-a with dopamin inhibitor (Ovopel, Dagin, Ovaprim) and their benefits were studied, compared with homogenate of carp pituitary (CPE), during controlled reproduction of weatherfish (Misgurnus fossilis, Linnaeus, 1758) in artificial conditions on the quality of the produced fry. The goal of this thesis was assess the suitability of individual commercially produced hormonal preparations for controlled reproduction of weatherfish and the possibility to replace with them unstandardized use of homogenate of carp pituitary. It was found that use of various hormonal preparations and dosage may to in some extent affect hatchability and survival rate of larvae (fry), the size of the yolk sac of larvae, and the amount of energy deposited in body tissues of larvae. However, demonstrable difference in studied parameters for the application of different preparations on the different hormonal basis (hCG versus GnRH) was not reported. The highest rate of hatching larvae (93.3 ? 3.8%) was observed in the groups treated with preparation Pregnyl 3000 IU - kg-1. In terms of overall survival of the larvae (from deployment of hatched eggs until the end of the experiment) have proven to be the most effective medication Pregnyl 3000 IU - kg-1 (69.9 ? 12.1 %) and Dagin (60.56 ? 11.71 %). Within the thesis has been demonstrated no relationship between hormonal treatment used and the growth of larvae (in terms of achieved total length of body and dry weight). The amount of energy deposited into the body tissues of larvae (gross calorific value) was comparable in all groups, except Dagin preparation, which was recorded impairment losses. For the best, most effective and commendable for control of reproductive hormone preparation carp pituitary homogenate replacing the terms of the assessed indicators can be seen the preparation based on hCG and that is Pregnyl at a dose of 3000 IU - kg-1.
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