Pituitary Adenylate Cyclase-Activating Polypeptide Is an Auto/Paracrine Stimulator of Acute Progesterone Accumulation and Subsequent Luteinization in Cultured Periovulatory Granulosa/Lutein Cells

S. Gras
1999 Endocrinology  
Recently, we have demonstrated that pituitary adenylate cyclaseactivating polypeptide (PACAP) is transiently expressed in steroidogenic ovarian cells during the periovulatory period. This prompted us to establish an in vitro system in which the potential local regulatory role of PACAP during periovulatory progesterone production could be examined. Granulosa/lutein cells from PMSG-and human CG (hCG)stimulated immature rats were used. The cells were isolated from preovulatory follicles 4 -6 h
more » ... ollicles 4 -6 h after the hCG injection, at which time the transient ovarian PACAP expression begins in vivo. By immunocytochemistry on intact cells and RIA on cell extracts and culture medium, granulosa/lutein cells were found to accumulate and secrete PACAP during incubation. Furthermore, the cells responded to exogenous PACAP 38 with a rapid (10 Ϫ7 M induced a peak value 20-fold higher than controls at 2 h) and dose-dependent accumulation of progesterone. PACAP 38 (5 ϫ 10 Ϫ9 M), in combination with an approximately half-maximal dose of hCG (1 ng/ml), showed an additive effect on progesterone accumulation. Immunoneutralization of endogenously released PACAP was performed using the IgG fraction from a specific PACAP antiserum that dose-dependently inhibits the progesterone accumulating effect of exogenous PACAP 38. The acute
doi:10.1210/en.140.5.2199 pmid:10218972 fatcat:nt5jd4koqjewhd563io3czi3xi