title: Inhibition of 20 alpha-hydroxysteroid dehydrogenase activity by follicle-stimulating hormone and androgens in cultured rat granulosa cells: a search for the mechanism of action.
abstract: Alterations of progesterone metabolism and especially of 20 alpha-hydroxysteroid dehydrogenase (20 alpha-HSD) activity were studied in cultured rat granulosa cells following various treatments. The cells were incubated for up to 48 h with or without follicle-stimulating hormone (FSH), androgens, hydroxyflutamide, estrogens, chlorea toxin, and dibutyryl cAMP [Bu2 cAMP]. Subsequently, the cells were incubated for 3 h with [4-14 C] progesterone (0.5 microM). The progesterone utilization and accumulation of 20 alpha-reduced and 5 alpha-reduced metabolites were assessed following thin-layer chromatography separation of radiolabeled steroids. Both FSH (1 microgram/ml) and testosterone (0.5 microM) decreased the 20 alpha-HSD activity by decreasing the maximal velocity (by 52% and 37%, respectively) without changing significantly the Km value. The inhibition of 20 alpha-HSD was demonstrable following 12 and 24 h exposure to FSH and following 24 and 48 h exposure to testosterone. Effects comparable to that induced by testosterone were elicited by other androgens (androstenedione and 5 alpha-dihydrotestosterone), but not by estrogens (estradiol-17 beta and estrone). Hydroxyflutamide reversed testosterone-induced effects: the increase of endogenous progesterone accumulation and the decrease of 20 alpha-HSD activity. Both cholera toxin (0.001-10 micrograms/ml) and Bu2 cAMP (62.5-1000 micrograms/ml) caused a dose-dependent inhibition of 20 alpha-HSD activity. Present results indicate that: the inhibition of 20 alpha-HSD by both FSH and androgens may be of a noncompetitive nature; androgen action on 20 alpha-HSD may be a true androgenic, receptor-mediated effect; and cAMP may mediate the FSH action on 20 alpha-HSD activity.
mesh_terms: D015089:20-Hydroxysteroid Dehydrogenases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D043607:20-alpha-Hydroxysteroid Dehydrogenase; D000728:Androgens / Q000494:pharmacology*; D000735:Androstenedione / Q000494:pharmacology; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D013196:Dihydrotestosterone / Q000494:pharmacology; D004958:Estradiol / Q000494:pharmacology; D004970:Estrone / Q000494:pharmacology; D005260:Female; D005485:Flutamide / Q000031:analogs & derivatives / Q000494:pharmacology; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D006107:Granulosa Cells / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D011374:Progesterone / Q000378:metabolism* / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013739:Testosterone / Q000494:pharmacology
chemical_list: D000728:Androgens; D013196:Dihydrotestosterone; D004970:Estrone; C014290:hydroxyflutamide; D013739:Testosterone; D000735:Androstenedione; D011374:Progesterone; D004958:Estradiol; D003994:Bucladesine; D005485:Flutamide; D005640:Follicle Stimulating Hormone; D002772:Cholera Toxin; D015089:20-Hydroxysteroid Dehydrogenases; D043607:20-alpha-Hydroxysteroid Dehydrogenase