Michael A E, Webley G E
MRC/AFRC Comparative Physiology Research Group, Institute of Zoology, Regent's Park, London, U.K.
Mol Cell Endocrinol. 1991 Dec;82(2-3):207-14. doi: 10.1016/0303-7207(91)90033-o.
To investigate the involvement of cyclic AMP phosphodiesterase in the antigonadotrophic actions of prostaglandin F2 alpha (PGF2 alpha), human granulosa cells were cultured in serum-supplemented medium for 72 h, treated for 30 min with cloprostenol or phorbol myristate acetate (PMA) and then exposed to human chorionic gonadotrophin (hCG) +/- isobutyl-methylxanthine (IBMX) for a further 4 h. In the absence of IBMX, cloprostenol and PMA inhibited hCG-stimulated progesterone production. However, in the presence of 0.5 mM IBMX, inhibition of phosphodiesterase prevented these antigonadotrophic effects. Phosphodiesterase activity was assessed by a novel direct assay performed on intact cells after 3 days of culture. PGF2 alpha, cloprostenol and 4 beta-PMA all enhanced cAMP degradation whilst an inactive phorbol ester (4 alpha-PMA) had no effect. Down-regulation of protein kinase C by 4 beta-PMA pre-treatment prevented the subsequent stimulation of phosphodiesterase activity by both cloprostenol and 4 beta-PMA. We conclude that the antigonadotrophic actions of PGF2 alpha in cultured human granulosa cells involve a stimulation of cAMP phosphodiesterase mediated via protein kinase C.
为研究环磷酸腺苷磷酸二酯酶在前列腺素F2α（PGF2α）抗促性腺激素作用中的参与情况，将人颗粒细胞在补充血清的培养基中培养72小时，用氯前列醇或佛波酯肉豆蔻酸酯（PMA）处理30分钟，然后再暴露于人类绒毛膜促性腺激素（hCG）±异丁基甲基黄嘌呤（IBMX）中4小时。在没有IBMX的情况下，氯前列醇和PMA抑制hCG刺激的孕酮产生。然而，在存在0.5 mM IBMX的情况下，磷酸二酯酶的抑制可防止这些抗促性腺激素作用。培养3天后，通过对完整细胞进行的一种新型直接测定法评估磷酸二酯酶活性。PGF2α、氯前列醇和4β-PMA均增强了cAMP降解，而无活性的佛波酯（4α-PMA）则无作用。用4β-PMA预处理下调蛋白激酶C可防止随后氯前列醇和4β-PMA对磷酸二酯酶活性的刺激。我们得出结论，PGF2α在培养的人颗粒细胞中的抗促性腺激素作用涉及通过蛋白激酶C介导的cAMP磷酸二酯酶的刺激。
