In the present study, we have demonstrated that PRL stimulates PAI-I gene expression in a time- and dose-dependent manner in eCG-primed rat granulosa cells in vitro. This stimulation of PAI-I expression is dramatically enhanced by the presence of LH. PRL is also capable of inhibiting LH-induced tPA expression. The mechanism by which PRL with the gonadotropin synergistically super-in-duces PAI-I, while inhibiting tPA expression, in the eCG-primed granulosa cells is unknown. It has been demonstrated that a low dose of FSH through activation of adenylate cyclase induces PAI-I production in granulosa cells. ventolin inhaler
The present study further demonstrated that PRL alone in higher doses is also capable of inducing PAI-I gene expression by a mechanism that does not appear to involve activation of adenylate cyclase in the cell membrane because cAMP does not mimic the action of PRL (data not shown). GnRH or phorbol 12-myristate 13-acetate (PMA) has been shown to markedly stimulate PAI-I mRNA and activity levels in cultured granulosa cells. The increase in PAI-I expression in the cells by GnRH and PMA was completely inhibited by the coaddition of FSH to the culture.