Otsuka M, Kishi H, Arai K, Watanabe G, Taya K, Greenwald G S
Laboratory of Veterinary Physiology, Tokyo University of Agriculture and Technology, Fuchu, Japan.
Biol Reprod. 1997 Feb;56(2):423-9. doi: 10.1095/biolreprod56.2.423.
The time course for loss of ability of Graafian follicles to secrete inhibin and estradiol was investigated during induced follicular atresia. Cyclic hamsters were hypophysectomized on Day 1 (estrus) and injected s.c. with 30 IU eCG. Thereafter, these animals were given a single i.p. injection of antiserum to eCG on the morning of Day 4 to induce follicular atresia in a rapid and predictable manner. A drastic fall in plasma levels of estradiol and testosterone was noted within 1 h, whereas relatively high levels of plasma inhibin were maintained until 12 h, followed by an abrupt decline by 24 h. The first histological signs of pyknosis in granulosa cells appeared by 4 h, and breakdown of the mural granulosa layer was observed in most follicles by 8-12 h after immunoneutralization of circulating eCG. According to immunohistochemical analysis, inhibin activity was unchanged in granulosa cells at 12 h followed by a slight decline by 24 h, whereas positive reaction for aromatase in these cells rapidly declined by 8 h. Immunoreactivity of 17alpha-hydroxylase/C17,20-lyase (CYP 17) was also reduced in theca cells by 8 h. These results indicate that granulosa cells continue to secrete inhibin during the process of follicular atresia, although these cells quickly shut off the secretion of estradiol, and theca cells shut off the secretion of testosterone. The present results indicate as well that a rapid decline of estradiol and testosterone in plasma is an early sign of atresia in antral follicles. These results, therefore, suggest that the loss of enzymatic activity of aromatase in granulosa cells and CYP 17 in theca cells is a part of the process of follicular atresia.
在诱导卵泡闭锁过程中，研究了格拉夫卵泡分泌抑制素和雌二醇能力丧失的时间进程。在第1天（发情期）对周期性仓鼠进行垂体切除，并皮下注射30 IU人绒毛膜促性腺激素（eCG）。此后，在第4天上午对这些动物腹腔注射一次抗eCG血清，以快速且可预测的方式诱导卵泡闭锁。在1小时内观察到血浆雌二醇和睾酮水平急剧下降，而血浆抑制素水平在12小时内维持相对较高水平，随后在24小时时急剧下降。颗粒细胞固缩的首个组织学迹象在4小时出现，在循环eCG免疫中和后8 - 12小时，大多数卵泡观察到壁颗粒层破裂。根据免疫组织化学分析，颗粒细胞中的抑制素活性在12小时时未改变，随后在24小时时略有下降，而这些细胞中芳香化酶的阳性反应在8小时时迅速下降。卵泡膜细胞中17α - 羟化酶/C17,20 - 裂解酶（CYP 17）的免疫反应性在8小时时也降低。这些结果表明，在卵泡闭锁过程中颗粒细胞继续分泌抑制素，尽管这些细胞迅速停止雌二醇的分泌，并且卵泡膜细胞停止睾酮的分泌。目前的结果还表明，血浆中雌二醇和睾酮的快速下降是窦状卵泡闭锁的早期迹象。因此，这些结果表明颗粒细胞中芳香化酶和卵泡膜细胞中CYP 17酶活性的丧失是卵泡闭锁过程的一部分。
