Coordinated Regulation of Tissue Type Plasminogen Activator and Plasminogen Activator Inhibitor Type-1 Gene Expression in Hypophysectomized Rat Ovaries During GnRHa-Induced Ovulation

摘要

In this study we have demonstrated that both granulosa and theca-interstitial cells of hy-pophysectomized rat ovaries are capable of synthesizing tPA and PAI-1.Injection of a GnRH agonist canmarkedly induce these gene expressions in the ovary in a cell-specific and time-coordinated manner,so that asurge of tPA mRNA and its activity in both granulosa and theca-interstitial cells was obtained just prior toovulation.Theca-interstitial cells make PAI-1 become the most active in the ovary.Both the amount PAI-1mRNA and its activity in the cells reach the maximum level 6 h before the tPA peak.By contrast,granulosacells produce only a little amount of PAI-1 (most increase tPA activity),and both PAI-1 mRNA and activityin the cells reach the maximum after ovulation.The coordinated regulation of tPA and PAI-1 in the ovarymay fine-tune the peak of tPA activity which may be important for the regulation of the ovulatory process.The changes of tPA and PAI-1 in the ovarian cells of hypophysectomized rats during GnRHa-induced ovula-tion are similar to that in intact rats during hCG-induced ovulation,suggesting that the ovulatory process canbe modulated by different regulatory signals mediated by influencing the coordinated expression of both tPAand PAI-1.