Nancarrow C D, Evison B M, Connell P J
Biol Reprod. 1982 Mar;26(2):263-9. doi: 10.1095/biolreprod26.2.263.
An investigation of the control of the function of the corpus luteum of early pregnancy in sheep has been carried out by assessing the luteolytic effects of a dose of 100 micrograms of the synthetic prostaglandin, cloprostenol. Cloprostenol injected into 21-day pregnant sheep carrying single or multiple embryos caused luteolysis and termination of pregnancy within 2--5 days in 8 of 23 sheep. The mean numbers of corpora lutea in these ewes differed significantly from those which carried their pregnancy (1.8 +/- 0.3, SEM, vs 3.2 +/- 0.4; P less than 0.05). It appeared that the greater number of embryos, or a greater mass of embryonic tissue, afforded increased protection to the corpora lutea through unidentified antiluteolytic or luteotrophic factors. The number of corpora lutea present did not appear to be an operative factor, as the same dose of cloprostenol was luteolytic in 43 of 46 nonpregnant ewes with 1--6 corpora lutea; the 3 refractive ewes each having only 1 corpus luteum. The progesterone concentration in the plasma of pregnant ewes which underwent luteolysis following cloprostenol treatment was 0.5 +/- 0.1 ng/ml 48 h after injection, while that of the ewes remaining pregnant was significantly higher at 2.1 +/- 0.3 ng/ml. Seven of these refractive ewes which were given a second injection of cloprostenol on Day 28 of pregnancy subsequently experienced luteolysis and abortion. The corpora lutea of the remaining 8 ewes were not affected by saline injections given on Day 28, but 4 of these ewes later aborted after Day 44. It is concluded that pregnancies on ewes carrying 1 embryo can be terminated by a single dose of 100 micrograms cloprostenol given around Day 21 of pregnancy, but 2 injections given about 7 days apart may be needed when multiple embryos are present. Hormonal control of the sensitivity of the corpus luteum to luteolytic prostaglandins appears to reside in the conceptus in such a way that a decrease in sensitivity is related to the number of embryos present.
通过评估100微克合成前列腺素氯前列醇的溶黄体作用，对绵羊早期妊娠黄体功能的控制进行了一项研究。给怀有单胎或多胎胚胎的21天妊娠绵羊注射氯前列醇，23只绵羊中有8只在2至5天内发生黄体溶解并终止妊娠。这些母羊的黄体平均数量与正常妊娠母羊有显著差异（1.8±0.3，标准误，对比3.2±0.4；P<0.05）。似乎更多数量的胚胎或更大质量的胚胎组织，通过未知的抗溶黄体或促黄体因子，为黄体提供了增强的保护。黄体数量似乎不是一个起作用的因素，因为相同剂量的氯前列醇对46只具有1至6个黄体的未妊娠母羊中的43只具有溶黄体作用；3只抵抗的母羊每只仅有1个黄体。氯前列醇治疗后发生黄体溶解的妊娠母羊血浆中孕酮浓度在注射后48小时为0.5±
