Hormonal control of urokinase plasminogen activator secretion by sheep ovarian surface epithelial cells

Secretion of urokinase plasminogen activator (uPA) by ovarian surface epith elium (OSE) adjacent to the preovulatory ovine follicle has been implicated in apical tissue degradation and follicular rupture. In vitro experiments were designed to test the hypothesis that uPA release by OSE is under direc t hormonal control. Epithelial cells were isolated from the ovarian surface of sheep using a polytetrafluorethylene scraper designed to dislodge adher ent cells from culture flasks. Amidolytic cleavage of a uPA-specific chromo gen (carbobenzoxy-L-gamma-glutamyl [alpha-ot-but]-glycyl-arginine-p-nitroan ilide monoacetate) was used as a measure of enzymatic bioactivity in OSE-co nditioned incubation media. Secretion of uPA by OSE suspensions from proest rous ewes was stimulated by exposure (2 h) to a preovulatory surge-like con centration of LH. OSE cells obtained during the luteal phase or anestrus we re not responsive to LH. Baseline rates of uPA secretion and expression of estradiol receptors (in situ immunofluorescence detection) were not affecte d by reproductive status. Induction of uPA secretion by anestrous OSE was a ttained after priming (6 h) with estradiol-17 beta; responsiveness was attr ibuted to gonadotropin receptor (ligand binding) up-regulation. Monolayers of OSE established on polyethylene membranes secreted uPA predominately in a basal (i.e., toward the substratum) direction. We suggest that OSE in jux taposition with the (hyperemic) wall of the preovulatory follicle is perfus ed by surge levels of LH, invoking uPA release into underlying ovarian tiss ues.