Inhibition of luteinizing hormone/human chorionic gonadotropin-stimulable adenylyl cyclase activity in rat luteal membranes by nonsteroidal component(s) in human follicular fluid.

We examined the ability of nonsteroidal components of human follicular fluid (hFF) to alter gonadotropin responsiveness using the LH/hCG-sensitive adenylyl cyclase system of rat luteal membranes. Follicular aspirates were obtained from regularly ovulatory women (n = 10) whose follicles were stimulated by human menopausal gonadotropin and hCG as part of an in vitro fertilization program. hFF from large follicles was pooled and extracted with 10% (wt/vol) activated charcoal. Maximal hCG stimulation of adenylyl cyclase activity obtained with 10 μg/ml hCG and 100 μM of the hydrolysisresistant GTP analog guanyl 5 ′-yl-imidodiphosphate was significantly inhibitedby hFF in a dose-dependent manner. Addition of about 500 μg hFF protein caused inhibition of 70% compared to the control value. Fractionations of hFF by ultrafiltration using membranes of precalibrated pore size demonstrated that the inhibitory activity was associated with a less than 10,000 mol wt fraction; 3 μg protein/assay of this fraction resulted ...