Interaction and regulation of plasminogen activators and their inhibitor in rat follicles during periovulatory periods.

Ovarian follicles produce two types of plasminogen activator (tPA and uPA), and their inhibitor (PAI). We have examined the interaction and regulation of these factors in ovarian intact follicles as well as granulosa and theca-interstitial cells. The results show that only tPA, but not uPA, is regulated by the gonadotropins and reaches maximum prior to ovulation. PAI is secreted mainly by theca-interstitial cells and is stimulated also by the gonadotropins. The formation of complexes between PA and PAI completely blocks or decreases PA activity. It is suggested that the interaction between plasminogen activators and their inhibitor in the follicles may play a very important role in maintaining normal ovarian function and the machnism of ovulation.