A GnRH agonist (5-50 μg) is capable of inducing ovulation in PMSG-primed hypophy-sectomized immature rats, as is the case in hCG-induced ovulation, but 2-4 h earlier than hCG. GnRH-induced ovulation is effectively bl...A GnRH agonist (5-50 μg) is capable of inducing ovulation in PMSG-primed hypophy-sectomized immature rats, as is the case in hCG-induced ovulation, but 2-4 h earlier than hCG. GnRH-induced ovulation is effectively blocked by the concomitant administration of the GnRH-antagonist which failed to interfere with hCG-induced ovulation, indicating that GnRH and its agonists do not share a receptor with LH/hCG. Like hCG, GnRH is also capable of inducing tissue type (tPA), but not urokinase type (uPA) PA. The plasminogen activator activity in ovarian homogenates and the granulosa and theca-interstitial cells increase in a time-dependent manner, reaching maximum levels just prior to ovulation. Similar to hCG, GnRH also increases tPA activity in cumulus-oocyte complexes in a time-dependent fashion.展开更多
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...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.展开更多
基金Project supported by NIH Research Grant(HD-14084), Rockefeller Foundation, New York and the National Natural Science Foundation of China.
文摘A GnRH agonist (5-50 μg) is capable of inducing ovulation in PMSG-primed hypophy-sectomized immature rats, as is the case in hCG-induced ovulation, but 2-4 h earlier than hCG. GnRH-induced ovulation is effectively blocked by the concomitant administration of the GnRH-antagonist which failed to interfere with hCG-induced ovulation, indicating that GnRH and its agonists do not share a receptor with LH/hCG. Like hCG, GnRH is also capable of inducing tissue type (tPA), but not urokinase type (uPA) PA. The plasminogen activator activity in ovarian homogenates and the granulosa and theca-interstitial cells increase in a time-dependent manner, reaching maximum levels just prior to ovulation. Similar to hCG, GnRH also increases tPA activity in cumulus-oocyte complexes in a time-dependent fashion.
基金supported by Swedish Medical Research Council,the State Family Planning Commissionthe National Natural Science Foundation of China.
文摘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.
