title: Inhibition of FSH augmented adenylate cyclase activity in porcine granulosa cells by ovarian protein.
abstract: We sought to evaluate the effects of a fraction of porcine follicular fluid, termed follicle regulatory protein (FRP), on FSH-induced adenylate cyclase activity in porcine granulosa cell membranes using Gpp(NH)p and forskolin as pharmacological probes of adenylate cyclase activity. Without FSH treatment, the addition of 100 micrograms/ml of the FRP fraction induced a significant decrease in Gpp(NH)p stimulated cyclase activity while maximal inhibition of cAMP formation was achieved with 1 mg/ml of FRP. Granulosa cells cultured with FSH reached a maximum in adenylate cyclase activity at 20 min which returned to baseline by 45 minutes. FRP induced a reduction in adenylate cyclase activity during this same interval of time. Adenylate cyclase activity of cells treated with FRP was unchanged in the presence of methyl-isobutal-xanthine. Further, when FRP was heated (56 degrees C, 45 min) or precipitated with 10% TCA, it was unable to inhibit adenylate cyclase. The 50% inhibitory dose (ID50) for FRP inhibition of adenylate cyclase activity in cells stimulated with Gpp(NH)p was 80 micrograms/ml and 500 micrograms/ml when granulosa cells were preincubated with FSH prior to Gpp(NH)p stimulation. The ID50 for the FRP inhibition of forskolin stimulated adenylate cyclase activity was 500 micrograms/ml. Gpp(NH)p stimulated adenylate cyclase activity was more sensitive than forskolin stimulated activity to inhibition by FRP. In conclusion, the data presented here demonstrate that a partially purified fraction of porcine follicular fluid inhibited FSH responsive adenylate cyclase activity in porcine granulosa cells.
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D005576:Colforsin / Q000494:pharmacology; D005260:Female; D005640:Follicle Stimulating Hormone / Q000494:pharmacology*; D006107:Granulosa Cells / Q000187:drug effects / Q000201:enzymology*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D066298:In Vitro Techniques; D036341:Intercellular Signaling Peptides and Proteins; D007700:Kinetics; D010455:Peptides / Q000494:pharmacology*; D013552:Swine; D014238:Trichloroacetic Acid
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; C018355:intraovarian peptides; D005576:Colforsin; D006165:Guanylyl Imidodiphosphate; D014238:Trichloroacetic Acid; D005640:Follicle Stimulating Hormone; D000262:Adenylyl Cyclases; D015056:1-Methyl-3-isobutylxanthine