Smart D, Singh I, Smith R F, Dobson H
Department of Veterinary Clinical Science, University of Liverpool, Neston, South Wirral, UK.
J Reprod Fertil. 1994 May;101(1):115-9. doi: 10.1530/jrf.0.1010115.
The effects of time postpartum and suckling status on the oestradiol-induced LH surge in ewes and some of the possible mechanisms involved were investigated. Lambs were removed from nonsuckled ewes at parturition (day 0) and the ewes hand-milked 12 and 48 h later to prevent discomfort. Nonsuckled ewes on day 1, 7, 14 or 28, and suckled ewes on day 7 or 28 postpartum were injected i.m. with 50 micrograms oestradiol benzoate (hour 0). A further eight suckled ewes were given oestradiol on day 1 (as above), and four were also given naloxone (1 mg kg-1 h-1) from 10 until 14 h after administration of oestradiol benzoate. There was no LH surge in response to oestradiol on day 1. In nonsuckled ewes the onset of the LH surge was significantly (P < 0.05) delayed when oestradiol was administered on day 7 (17.4 +/- 1.5 h), compared with when it was injected on days 14 and 28 postpartum (14.4 +/- 1.7 and 14.0 +/- 1.4 h). The LH surge was also delayed (P < 0.05) when oestradiol was administered on day 7 (18.0 +/- 2.8 h) in suckled ewes. There was no difference in the duration or amplitude of the LH surge with time postpartum in nonsuckled ewes. Suckling significantly (P < 0.05) reduced the amplitude of the LH surge on both day 7 (21.0 +/- 2.4 versus 26.4 +/- 2.3 ng ml-1) and day 28 (23.6 +/- 3.2 versus 28.8 +/- 2.9 ng ml-1), but had no effect on the onset or duration of the surge.(ABSTRACT TRUNCATED AT 250 WORDS)
研究了产后时间和哺乳状态对母羊雌二醇诱导的促黄体生成素（LH）激增的影响以及一些可能涉及的机制。分娩时（第0天）从非哺乳母羊中带走羔羊，12小时和48小时后人工挤奶以防止不适。产后第1、7、14或28天的非哺乳母羊以及产后第7或28天的哺乳母羊于0小时肌肉注射50微克苯甲酸雌二醇。另外8只哺乳母羊在第1天给予雌二醇（如上所述），其中4只在给予苯甲酸雌二醇后10至14小时还给予纳洛酮（1毫克/千克/小时）。第1天对雌二醇无LH激增反应。在非哺乳母羊中，与产后第14天和28天注射（分别为14.4±1.7小时和14.0±1.4小时）相比，第7天给予雌二醇时LH激增的开始显著延迟（P<0.05）（17.4±1.5小时）。在哺乳母羊中，第7天给予雌二醇时LH激增也延迟（P<0.05）（18.0±2.8小时）。非哺乳母羊中LH激增的持续时间或幅度随产后时间无差异。哺乳显著（P<0.05）降低了第7天（分别为21.0±2.4对26.4±2.3纳克/毫升）和第28天（23.6±3.2对28.8±2.9纳克/毫升）LH激增的幅度，但对激增的开始或持续时间无影响。（摘要截短为250字）
