Hashimoto Naohiro, Kishimoto Takeo, Nagahama Yoshitaka
Zoological Institute, Faculty of Science, University of Tokyo, Hongo, Tokyo 113, Japan.
Laboratory of Reproductive Biology, Department of Developmental Biology, National Institute for Basic Biology, Myodaijich, Okazaki 444, Japan.
Dev Growth Differ. 1985;27(6):709-716. doi: 10.1111/j.1440-169X.1985.00709.x.
A continuous exposure of follicle-enclosed mouse oocytes to ovine luteinizing hormone (LH, 10 μg/ml) in vitro resulted in a 3-fold elevation of CAMP levels in the follicle cells, but not the oocytes, with subsequent oocyte maturation. When follicle-enclosed oocytes were exposed to forskolin (0.01-10 μM) for 2 hr and then incubated in forskolin-free medium (transient exposure group), oocytes underwent germinal vesicle breakdown in a dose-dependent manner. In contrast, a continuous exposure of the follicles to forskolin (10 μM) for up to 10 hr failed to induce resumption of meiosis. Follicle cell cAMP levels increased within 2 hr after the initial exposure to forskolin, and thereafter decreased rapidly regardless of whether forskolin treatment was transient or continuous. A similar transient increase in oocyte cAMP levels was observed after transient or continuous treatment with forskolin. It was evident, however, that at any time examined oocyte cAMP levels were consistently higher in the continuous exposure group than in the transient exposure group. Furthermore, a continuous exposure to forskolin also blocked LH-induced meiotic maturation. These findings suggest that elevated levels of cAMP in the oocyte block meiotic maturation in mouse oocytes. The present results further suggest that an increase in follicle cell cAMP levels is essential to the LH-induced meiotic maturation.
在体外将包裹卵泡的小鼠卵母细胞持续暴露于绵羊促黄体生成素（LH，10μg/ml）中，会导致卵泡细胞而非卵母细胞中的环磷酸腺苷（CAMP）水平升高3倍，随后卵母细胞成熟。当将包裹卵泡的卵母细胞暴露于福斯可林（0.01 - 10μM）2小时，然后在无福斯可林的培养基中孵育（短暂暴露组）时，卵母细胞以剂量依赖的方式发生生发泡破裂。相比之下，将卵泡持续暴露于福斯可林（10μM）长达10小时未能诱导减数分裂恢复。在最初暴露于福斯可林后2小时内，卵泡细胞的环磷酸腺苷水平升高，此后无论福斯可林处理是短暂还是持续，其水平均迅速下降。在用福斯可林短暂或持续处理后也观察到卵母细胞环磷酸腺苷水平有类似的短暂升高。然而，很明显，在任何检测时间，持续暴露组的卵母细胞环磷酸腺苷水平始终高于短暂暴露组。此外，持续暴露于福斯可林也会阻断LH诱导的减数分裂成熟。这些发现表明，卵母细胞中环磷酸腺苷水平升高会阻断小鼠卵母细胞的减数分裂成熟。目前的结果进一步表明，卵泡细胞环磷酸腺苷水平的升高对于LH诱导的减数分裂成熟至关重要。
