title: Estradiol-17 beta interference with meiotic maturation in Rana pipiens ovarian follicles: evidence for inhibition of 3 beta-hydroxysteroid dehydrogenase.
abstract: Increasing doses of estradiol-17 beta added to in vitro incubations inhibited pregnenolone-induced germinal vesicle breakdown in Rana pipiens ovarian follicles. The inhibition was reversed with increasing concentrations or pregnenolone added to the medium. Because no evidence of estradiol-17 beta inhibition or interaction with progesterone-induced GVBD was observed, the effect of estradiol-17 beta on the conversion of 3H-pregnenolone to 3H-progesterone was investigated. Estradiol-17 beta in doses as low as 10(-7) M significantly inhibited the conversion of 3H-pregnenolone to 3H-progesterone in follicles incubated in vitro. It is suggested that estradiol-17 beta is a feedback inhibitor of 3 beta-hydroxysteroid dehydrogenase-isomerase, the enzyme complex that converts pregnenolone to progesterone, a necessary step in the initiation of GVBD.
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000037:antagonists & inhibitors*; D000818:Animals; D001001:Anura; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D008540:Meiosis / Q000187:drug effects*; D006080:Ovarian Follicle / Q000187:drug effects*; D011284:Pregnenolone / Q000378:metabolism / Q000494:pharmacology; D011374:Progesterone / Q000378:metabolism / Q000494:pharmacology; D011894:Rana pipiens
chemical_list: D011374:Progesterone; D004958:Estradiol; D011284:Pregnenolone; D015096:3-Hydroxysteroid Dehydrogenases