Yokota H, Yamada K, Liu X, Kobayashi J, Abe Y, Mizunuma H, Ibuki Y
Department of Obstetrics and Gynecology, Gunma University School of Medicine, Maebashi, Japan.
Endocrinology. 1997 Nov;138(11):4572-6. doi: 10.1210/endo.138.11.5526.
Activin A is a gonadal protein originally isolated from follicular fluid and is recognized as a local regulator of granulosa cell differentiation. Whether activin A promotes folliculogenesis, however, still remains unclarified. The present study was designed to elucidate the effect of activin A on follicular growth in in vitro follicle culture systems. Preantral follicles, 100-120 microm in diameter, were mechanically isolated from BDF1 hybrid immature mice (11 days old) and adult mice (8 weeks old), then cultured for 4 days in a serum-free medium supplemented with activin A (100 ng/ml), FSH (100 mIU/ml), and a combination of both. Follicular diameter was measured daily, and the amount of estradiol and inhibin released at day 4 was determined by RIA. Preantral follicles collected from immature mice showed a significant increase in diameter when cultured with activin A or both activin A and FSH. FSH alone showed no significant effect on the diameter of follicles from immature mice. In contrast, the diameter of preantral follicles from adult mice significantly increased in response to FSH. Activin A did not stimulate growth of follicles from adult mice, and more interestingly, blocked the effect of FSH. The inhibitory action of activin A was in part restored by co-culture with follistatin (100 ng/ml). These results indicate that activin A is folliculogenetic in the prepubertal mouse, but not in adults.
激活素A是一种最初从卵泡液中分离出来的性腺蛋白，被认为是颗粒细胞分化的局部调节因子。然而，激活素A是否促进卵泡发生仍不清楚。本研究旨在阐明激活素A在体外卵泡培养系统中对卵泡生长的影响。从BDF1杂交未成熟小鼠（11日龄）和成年小鼠（8周龄）中机械分离出直径为100-120微米的窦前卵泡，然后在补充有激活素A（100纳克/毫升）、促卵泡激素（100毫国际单位/毫升）以及两者组合的无血清培养基中培养4天。每天测量卵泡直径，并通过放射免疫分析法测定第4天释放的雌二醇和抑制素的量。从未成熟小鼠收集的窦前卵泡在与激活素A或激活素A和促卵泡激素一起培养时，直径显著增加。单独使用促卵泡激素对未成熟小鼠卵泡的直径没有显著影响。相比之下，成年小鼠的窦前卵泡直径对促卵泡激素有显著增加。激活素A没有刺激成年小鼠卵泡的生长，更有趣的是，它阻断了促卵泡激素的作用。通过与卵泡抑素（100纳克/毫升）共培养，激活素A的抑制作用部分得到恢复。这些结果表明，激活素A在青春期前小鼠中具有卵泡生成作用，但在成年小鼠中则不然。
