Dang B T, Voogt J L
Department of Physiology and Biophysics, University of Louisville Health Sciences Center, Kentucky 40201.
Endocrinology. 1977 Mar;100(3):873-80. doi: 10.1210/endo-100-3-873.
Pseudopregnancy (PP) in the rat is characterized by maintenance of the corpora lutea and twice daily surges of prolactin at 1500-2100 h and 0100-0900 h. Four days after PP was induced by cervical stimulation with a glass rod, rats were cannulated via the right carotid artery and one day later received an implant of ovine prolactin (200-250 mg) or albumin (controls) into the median eminence of the hypothalamus. Forty-five of 54 rats implanted with prolactin showed a termination of PP within 4 days. Ova were recovered from 19 of these rats whereas all of the controls remained pseudopregnant and did not ovulate. Ovarian and uterine weights were increased in rats implanted with prolactin. Plasma prolactin levels in the rats implanted with prolactin were lower each day (45-89%) at 0100, 0300 and 1800 h compared to controls. Plasma LH levels rose gradually after prolactin implantation, and in those rats in which ovulation occurred, a preovulatory LH rise was detected at 1800 h on the previous day. It is concluded that daily surges of prolactin play an essential role in maintaining PP in the rat, and that implantation of prolactin into the median eminence results in inhibition of prolactin. The stimulation of LH secretion, which led to ovulation, may be the result of a direct neural action of prolactin on the LH release mechanism or may simply result from the termination of PP.
大鼠假孕（PP）的特征是黄体维持以及在15:00 - 21:00时和01:00 - 09:00时催乳素每天出现两次高峰。在用玻璃棒刺激子宫颈诱导假孕4天后，通过右颈动脉对大鼠进行插管，一天后在下丘脑正中隆起植入羊催乳素（200 - 250毫克）或白蛋白（对照组）。植入催乳素的54只大鼠中有45只在4天内假孕终止。从其中19只大鼠中回收了卵子，而所有对照组大鼠仍处于假孕状态且未排卵。植入催乳素的大鼠卵巢和子宫重量增加。与对照组相比，植入催乳素的大鼠在01:00、03:00和18:00时的血浆催乳素水平每天都较低（45% - 89%）。植入催乳素后血浆促黄体生成素（LH）水平逐渐升高，在那些发生排卵的大鼠中，在前一天的18:00时检测到排卵前LH升高。得出的结论是，催乳素的每日高峰在维持大鼠假孕中起重要作用，并且在下丘脑正中隆起植入催乳素会导致催乳素受到抑制。导致排卵的LH分泌刺激可能是催乳素对LH释放机制的直接神经作用的结果，或者可能仅仅是假孕终止的结果。
