Modulation of prolactin receptors in cultured rat granulosa cells by FSH, LH and GnRH.
The hormonal modulation of prolactin (PRL)-binding capacity of rat granulosa cells was studied. Granulosa cells obtained from immature, hypophysectomized, estrogen-treated rats were cultured for 2 days in a serum-free medium in the presence of various hormones. FSH treatment in vitro stimulated granulosa cell PRL-binding capacity by approximately 4-6-fold in a dose-dependent manner. Concomitant treatment with 10-8 M GnRH inhibited the FSH-induced increase in PRL-binding capacity by 64%. In contrast, the inhibitory effect of GnRH was blocked by concomitant treatment with 10-6 M of a GNRH antagonists, [D-pGlu1, D-Phe2, D-Trp3,6]GnRH. PRL-binding capacity was also increased (approximately 2-fold) by in vitro treatment with cholera toxin (10 microgram/ml). In granulosa cells pre-treated with FSH in vitro for 2 days, hCG treatment for 2 additional days stimulated PRL-binding capacity in a dose-dependent manner (approximately 2-fold). Likewise, treatment with LH (100 ng/ml) also stimulated PRL-binding capacity by approximately 2-fold. These in vitro studies demonstrated that gonadotropins (FSH, LH and hCG) directly enhanced PRL binding by granulosa cells, whereas GnRH inhibited FSH action.
D000818:Animals; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D007987:Gonadotropin-Releasing Hormone / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D006107:Granulosa Cells / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000494:pharmacology*; D011388:Prolactin / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000187:drug effects*; D011981:Receptors, Prolactin
D006063:Chorionic Gonadotropin; D011956:Receptors, Cell Surface; D011981:Receptors, Prolactin; D007987:Gonadotropin-Releasing Hormone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D002772:Cholera Toxin