Lu K H, Chen H I, Grandison L, Huang H H, Meites J
Endocrinology. 1976 May;98(5):1235-40. doi: 10.1210/endo-98-5-1235.
The ability of the pituitary to release LH in response to synthetic LHRH was tested in lactating female rats on days 7 and 17 post partum, and compared with that of normal cycling female rats on diestrous day 2 (controls). Three consecutive injections of LHRH (100 ng/100 g BW, sc), each 50 min apart, were given to each rat and sequential blood samples were collected at 25-min intervals by cardiac puncture under light ether anesthesia. In all 3 groups, the 2nd and 3rd injections of LHRH produced much greater increases in serum concentrations of LH than the 1st injection. However, this self-priming effect of LHRH on LH response was markedly attenuated in the postpartum lactating rats (PPL), compared with the normal cycling female rats on diestrous day 2. Three consecutive injections of LHRH produced significantly less LH release in PPL rats than in normal cycling female rats on diestrous day 2. Both day 7 and day 17 PPL rats released equally small amounts of LH in response to LHRH administration. The total amount of LH released by anterior pituitaries (APs) during a 5 h incubation in medium-199, from day 7 or day 17 in PPL rats, was significantly less than that released by the APs from normal cycling female rats on diestrous day 2. APs from day 7 and day 17 PPL rats also released less LH in vitro in response to LHRH (50 ng) stimulation than APs from normal cycling female rats. When APs from normal cycling female rats on diestrous day 2 were incubated with LHRH, the increments in LH release were greater at the end of the 2nd and 3rd h than after the 1st h of incubation. However, such increments in LH release were relatively small when APs from day 7 or day 17 PPL rats were similarly incubated with LHRH.
在产后第7天和第17天的哺乳期雌性大鼠中测试垂体对合成促黄体生成素释放激素（LHRH）产生反应释放促黄体生成素（LH）的能力，并与处于动情间期第2天的正常发情周期雌性大鼠（对照组）进行比较。给每只大鼠连续3次注射LHRH（100 ng/100 g体重，皮下注射），每次间隔50分钟，在轻度乙醚麻醉下通过心脏穿刺每隔25分钟采集一次序贯血样。在所有3组中，LHRH的第2次和第3次注射引起的血清LH浓度升高比第1次注射大得多。然而，与处于动情间期第2天的正常发情周期雌性大鼠相比，LHRH对LH反应的这种自身预激作用在产后哺乳期大鼠（PPL）中明显减弱。连续3次注射LHRH后，PPL大鼠释放的LH明显少于处于动情间期第2天的正常发情周期雌性大鼠。产后第7天和第17天的PPL大鼠对LHRH给药释放的LH量同样很少。在M-199培养基中培养5小时期间，产后第7天或第17天的PPL大鼠垂体前叶（APs）释放的LH总量明显少于处于动情间期第2天的正常发情周期雌性大鼠的垂体前叶释放的量。产后第7天和第17天的PPL大鼠的垂体前叶在体外对LHRH（50 ng）刺激释放的LH也比正常发情周期雌性大鼠的垂体前叶少。当处于动情间期第2天的正常发情周期雌性大鼠的垂体前叶与LHRH一起培养时，培养第2小时和第3小时末LH释放的增加比培养第1小时后更大。然而，当产后第7天或第17天的PPL大鼠的垂体前叶与LHRH进行类似培养时，LH释放的这种增加相对较小。
