Jenkin G, Heap R B, Symons D B
J Reprod Fertil. 1977 Mar;49(2):207-14. doi: 10.1530/jrf.0.0490207.
In sheep the basal concentration of LH in jugular vein plasma was significantly higher during the first 50 days of gestation in late pregnancy or at parturition. The pituitary response to a single i.v. injection of 200 microng synthetic LH-RH was determined at different stages of gestation and compared with that of anoestrous and cyclic sheep. Pituitary response to LH-RH decreased progressively with advancing gestation: by 56 days after mating the response had declined to 35% and by parturition to 14% of the value in anoestrous sheep. The pituitary response to LH-RH increased after parturition and the pattern of recovery differed in non-lactating and lactating sheep. By 63 days postpartum the response to LH-RH in non-lactating and lactating animals had returned to values similar to those in sheep during anoestrus and sheep during the luteal phase of the oestrous cycle. A decrease in pituitary responsiveness during pregnancy was associated with a decrease in pituitary content of LH. The quantity of LH released in response to a standard injection of LH-RH was linearly related to pituitary LH content.
在绵羊中，妊娠后期或分娩时妊娠前50天颈静脉血浆中促黄体生成素（LH）的基础浓度显著更高。在妊娠的不同阶段测定垂体对单次静脉注射200微克合成促黄体生成素释放激素（LH-RH）的反应，并与处于乏情期和发情周期的绵羊进行比较。垂体对LH-RH的反应随着妊娠进展而逐渐降低：交配后56天时反应已降至乏情期绵羊的35%，到分娩时降至14%。产后垂体对LH-RH的反应增加，非泌乳和泌乳绵羊的恢复模式不同。产后63天时，非泌乳和泌乳动物对LH-RH的反应已恢复到与乏情期绵羊以及发情周期黄体期绵羊相似的值。妊娠期间垂体反应性的降低与垂体中LH含量的减少有关。对标准剂量LH-RH注射所释放的LH量与垂体LH含量呈线性相关。
