Direct stimulation of ovarian progesterone-metabolizing enzyme by gonadotropin-releasing hormone in cultured granulosa cells.

摘要: The mechanism by which gonadotropin-releasing hormone (GnRH) inhibits ovarian progesterone production was investigated studying the GnRH modulation of 20 alpha-hydroxysteroid dehydrogenase activity in cultured rat granulosa cells. cells obtained from hypophysectomized, estrogen-treated rats were treated with various hormones vitro and determined measuring conversion radiolabeled alpha-hydroxy-pregn-4-en-3-one to progesterone. Treatment follicle-stimulating (FSH) increased 1.3-fold control value. Concomitant treatment 10(-8) M further enhanced FSH stimulation enzyme 2.6-fold increases associated maximum velocity, while Km values remained unchanged. In contrast, prolactin (PRL) FSH-primed resulted an 88% decrease as compared untreated controls. partially blocked this inhibitory effect. Furthermore, incubation for 2 days alone a 2.7-fold increase activity, all experiments, effect concomitant antagonist. These results suggest that one FSH- PRL-stimulated is through converts less active metabolite.