title: Differential effects of prostaglandin F2alpha on in vitro luteinized bovine granulosa cells.
abstract: Prostaglandins have been implicated in various aspects of ovarian function including ovulation and luteolysis. In this study, the expression and regulation of inducible prostagland in G/H synthase (PGHS-2) and PGF(2alpha) receptors were investigated in bovine granulosa cells at various stages of differentiation. Firstly, the induction of PGF(2alpha) receptor mRNA and PGHS-2 mRNA in preovulatory granulosa cells was evaluated. Granulosa cells were collected from preovulatory follicles and cultured for 1, 4, 7 or 10 days. Cells were treated with hCG (10 iu) or with increasing doses of forskolin (0-10 micromol l(-1)) for 24 h. Forskolin increased steady-state concentrations of mRNA for PGHS-2 (> 20-fold) and PGF(2alpha) receptor (> 1000-fold) in a dose-dependent fashion. Use of selective protein kinase A inhibitor (H89) reduced both hCG- and forskolin-induced expression of PGF(2alpha) receptor mRNA and PGHS-2 mRNA. The hypothesis that luteinized granulosa cells would acquire PGF(2alpha) responsiveness similar to responses to PGF(2alpha) observed in vivo was also evaluated. Treatment with PGF(2alpha) (100 nmol l(-1)) reduced forskolin-induced expression of PGF(2alpha) receptor mRNA on days 4, 7 and 10, but not on day 1 of culture (n = 3). Treatment with PGF(2alpha) did not change forskolin-induced expression of PGHS-2 mRNA on or before day 4 of culture. In contrast, PGF(2alpha) significantly increased PGHS-2 mRNA expression in granulosa cells primed with forskolin for 7 or 10 days. In conclusion, expression of PGHS-2 and PGF(2alpha) receptor mRNA is protein kinase A-dependent in preovulatory bovine granulosa cells. Granulosa cells become PGF(2alpha)-responsive soon after expression of PGF(2alpha) receptor, whereas further differentiation is required before PGF(2alpha) induces PGHS-2 mRNA upregulation. These results demonstrate that at least two key transitions are required in PGF(2alpha)-induced luteal regression in the mid-cycle corpus luteum.
authors.affiliation: Department of Physiology, National Cheng Kung University Medical College, Tainan, Taiwan, Republic of China. seantsai@mail.ncku.edu.tw
authors.forename: S J
authors.initials: SJ
authors.lastname: Tsai
authors.forename: M C
authors.initials: MC
authors.lastname: Wiltbank
mesh_terms: D000818:Animals; D002417:Cattle; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D015237:Dinoprost / Q000494:pharmacology*; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006107:Granulosa Cells / Q000187:drug effects* / Q000502:physiology*; D007700:Kinetics; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D011982:Receptors, Prostaglandin / Q000235:genetics
chemical_list: D006063:Chorionic Gonadotropin; D012333:RNA, Messenger; D011982:Receptors, Prostaglandin; C034671:prostaglandin F2alpha receptor; D005576:Colforsin; D015237:Dinoprost; D011451:Prostaglandin-Endoperoxide Synthases