Wright P J, Geytenbeek P E, Clarke I J, Findlay J K
J Reprod Fertil. 1980 Sep;60(1):171-6. doi: 10.1530/jrf.0.0600171.
The relationship between pituitary responsiveness to exogenous LH-RH, return of oestradiol-17 beta-induced positive-feedback effect on LH release and the resumption of oestrous cycles were studied in Merino ewes lambing in the breeding season. The mean (+/- s.e.m.) increase in plasma LH 2 h after 50 micrograms LH-RH i.v. was reduced (P < 0.001) in ewes tested in the last 4 weeks of pregnancy (8.6 +/- 2.1 ng/ml, N = 29) but was similar (P > 0.05) for non-parturient dioestrous ewes (N = 31) and for anoestrous ewes tested around 14 (N = 50) and 28 (N = 51) days post partum (30 +/- 3.9, 37.8 +/- 4.0, 39. 0 +/- 3.2 ng/ml, respectively). Oestradiol-positive feedback was absent in 68.6% (35/51) and 54% (27/50) of ewes tested around 14 and 28 days post partum, respectively. Neither LH-RH responsiveness nor the presence of oestradiol-postive feedback was related to the incidence of 61.9%, 166/268) or interval to (62 +/- 2.2 days, N = 99) first oestrus post partum. We suggest that these endocrine responses do not represent factor limiting the resumption of ovarian cyclicity post partum.
对繁殖季节产羔的美利奴母羊，研究了垂体对外源性促黄体激素释放激素（LH-RH）的反应性、雌二醇-17β诱导的对促黄体生成素（LH）释放的正反馈作用的恢复与发情周期恢复之间的关系。静脉注射50微克LH-RH后2小时，血浆LH的平均（±标准误）增加值在妊娠最后4周进行测试的母羊中降低（P<0.001）（8.6±2.1纳克/毫升，N=29），但未产的间情期母羊（N=31）以及产后约14天（N=50）和28天（N=51）测试的乏情期母羊中相似（P>0.05）（分别为30±3.9、37.8±4.0、39.0±3.2纳克/毫升）。产后约14天和28天测试的母羊中，分别有68.6%（35/51）和54%（27/50）不存在雌二醇正反馈。LH-RH反应性和雌二醇正反馈的存在均与产后首次发情的发生率（61.9%，166/268）或间隔时间（62±2.2天，N=99）无关。我们认为这些内分泌反应并不代表限制产后卵巢周期性恢复的因素。
