Proestrous hormone surges dissociated from ovulation in the estrogen-treated hamster.
Proestrous hormone surges dissociated from ovulation in the estrogen-treated hamster.
复制标题
在经过雌激素处理的仓鼠中，发情前激素激增与排卵无关。
作者：
G. S. Greenwald
金黄地鼠在月经周期的第一天(发情期)早上900h皮下注射50杯环戊酸雌二醇酯(ECP)，4天后阴道分泌物正常，但直到14-18天后才恢复排卵。注射ECP后，卵巢组织学显示正常排卵的卵泡(发育中的卵泡)在第1天下午是健康的，但到第2天闭锁。发育中的卵泡(8-12层颗粒层)在第3天下午重新出现；卵泡发育到发情前期(第4天)下午仍然迟缓。用放射免疫法测定ECP和油处理仓鼠的血清激素水平。ECP不能影响第一天正常高水平的FSH；然而，到了第二天，FSH和黄体生成素水平通常都检测不到。在第3天，ECP治疗组出现“反弹”现象，FSH和LH值均可检测到。两组排卵前促黄体生成素水平均在排卵第4天1200~1400h之间，而促卵泡刺激素在排卵前1400h开始升高，而对照组直到1600h才开始升高。FSH水平升高，通常在第一天观察到，在油处理组中出现，但在ECP组中没有。这很可能是ECP组在恢复排卵之前延迟很长时间的原因。体外反搏对黄体功能无影响；两组第1天和第2天的孕酮(P)循环水平约为12 ng/ml。第4天，ECP组和油组P分泌正常，但前者无大的有腔卵泡。ECP组在1500h的第1、2、3、4天雌二醇水平分别为250、263、255和273pg/ml，而对照组为34、80、105和297pg/ml。这些实验表明：a)ECP组第4天排卵前垂体激素的释放是正常的，但没有卵泡能够通过排卵做出反应；b)面对高雌激素水平，CL持续的功能活动是维持4天“周期”的原因；c)与大鼠相比，仓鼠对外源性雌激素具有极强的抵抗力。
Hamsters injected sc with 50 mug estradiol cyclopentylpropionate (ECP) at 0900 h on day 1 (metestrus) of the cycle show the normal "postovulatory" vaginal discharge 4 days later but do not resume ovulation until 14--18 days later. After ECP injection ovarian histology reveals that the follicles normally destined to ovulate at the end of the cycle (developing follicles) are healthy on the afternoon of day 1, but atretic by day 2. Developing follicles (8--12 granulosal layers) reappear by the afternoon of day 3; follicular development is still retarded by the afternoon of proestrus (day 4). Serum hormone levels were determined by RIA in ECP and oil treated hamsters. ECP fails to affect the normally high levels of FSH present throughout day 1; however, by day 2 both FSH and LH levels are usually undetectable. On day 3, a "rebound" phenomenon occurs and FSH and LH are now detectable in the ECP treated groups. The preovulatory increase of LH occurs on day 4 between 1200 and 1400 h in both groups whereas FSH increases at 1400 h in the ECP group but not until 1600 h in the controls. The elevated levels of FSH, usually observed throughout day 1, occur in the oil treated but not in the ECP group. This most likely accounts for the long delay before ovulation is resumed in the ECP group. Luteal function is unaffected by ECP; circulating levels of progesterone (P) are approximately 12 ng/ml on days 1 and 2 in both groups. The normal secretion of P on day 4 occurs in ECP and oil groups and in the absence of large antral follicles in the former animals. In the ECP group estradiol levels on days 1, 2, 3, 4 at 1500 h are 250, 263, 255, and 273 pg/ml respectively, compared to 34, 80, 105, and 297 pg/ml for the controls. These experiments demonstrate a) that the preovulatory release of anterior pituitary hormones on day 4 is normal in the ECP group but there are no follicles competent to respond by ovulating; b) that the continued functional activity of the CL in the face of elevated estrogen levels accounts for the maintenance of the 4 day "cycle"; and c) the extreme resistance to exogenous estrogen of the hamster as compared to the rat.