title: Effect of growth hormone releasing hormone on luteinizing hormone stimulated progestin biosynthesis in cultured rat ovarian granulosa cells.
abstract: In the present study, we examined the effects of growth hormone releasing hormone (GHRH) on luteinizing hormone (LH)-stimulated progestin biosynthesis. Granulosa cells from pregnant mare serum gonadotropin (PMSG)-treated immature rats were cultured in vitro in the absence or presence of ovine. National Institute of Health LH (100 ng/ml) with various doses of GHRH (10(-9), 10(-8) and 10(-7) mol/l) for 24 h. At the end of the incubation period, the incubation media were collected and levels of progesterone, 20 alpha-hydroxypregn-4-en-3-one and cyclic adenosine 3',5'-monophosphate (cAMP) were measured. GHRH significantly stimulated progesterone production and cAMP accumulation in media in a dose-dependent manner in the basal state (p < 0.01 and p < 0.001, respectively). In the presence of LH, GHRH significantly inhibited LH-stimulated progesterone production in a dose-dependent manner (p < 0.01), whereas increasing concentrations of GHRH produced progressive increases in cAMP accumulation (p < 0.05). Since increasing concentrations of GHRH produced progressive decreases in the ratio of progesterone to 20 alpha-hydroxypregn-4-en-3-one production in the LH-stimulated state (p < 0.01), GHRH may be involved in modulation of key steroidogenic steps concerned with progesterone degradation rather than formation in LH-stimulated rat granulosa cells. These results suggest that GHRH may regulate the effects of LH in granulosa cells and play an important role in the reproductive process.
authors.affiliation: Department of Obstetrics and Gynecology, University of Tsukuba, Ibaraki, Japan.
authors.forename: E
authors.initials: E
authors.lastname: Kotani
authors.forename: S
authors.initials: S
authors.lastname: Usuki
authors.forename: T
authors.initials: T
authors.lastname: Kubo
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D005260:Female; D006064:Gonadotropins, Equine; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D013007:Growth Hormone-Releasing Hormone / Q000494:pharmacology*; D007986:Luteinizing Hormone / Q000502:physiology*; D011372:Progestins / Q000096:biosynthesis*; D051381:Rats; D017208:Rats, Wistar
chemical_list: D006064:Gonadotropins, Equine; D011372:Progestins; D007986:Luteinizing Hormone; D013007:Growth Hormone-Releasing Hormone; D000242:Cyclic AMP