Leipheimer R E, Bona-Gallo A, Gallo R V
Endocrinology. 1984 May;114(5):1605-12. doi: 10.1210/endo-114-5-1605.
The aim of this study was to determine whether the rapid increases in LH pulse amplitude and frequency that occur within 24 h after ovariectomy (ovx) on diestrus day 1 (D1) were due to the removal of progesterone (P) and/or estradiol (E). Initial studies demonstrated that plasma levels of E and P were 18.2 +/- 1.2 pg/ml and 34.1 +/- 3.2 ng/ml, respectively, between the evening of D1 and the morning of D2 in our colony of intact rats. Immediately after ovx and jugular venous cannulation on the morning of D1, rats were implanted either with empty Silastic capsules or capsules capable of restoring physiological levels of E and P to the control values reported above. These rats were continuously bled (75 microliter/6 min) for 3 h 1 day after ovx for analysis of pulsatile LH release, and then additional plasma samples were gathered for determination of E and P levels. Rats with empty capsules had decreased levels of E and P and increases in mean blood LH levels, LH pulse amplitude, and pulse frequency. Animals with E capsules had physiological levels of E and decreased levels of P, but no suppression of the acute post-ovx increase in pulsatile LH release. In contrast, animals with P capsules had physiological plasma levels of P, decreased levels of E, and a marked reduction in the acute LH response to ovx. This suppression was due entirely to a decrease in LH pulse amplitude, as pulse frequency was not altered. Rats with E and P capsules had physiological levels of these hormones, which resulted in an even greater reduction in the acute LH response to ovx. This suppression was due to decreases in both LH pulse amplitude and pulse frequency. The effect of P on LH pulse amplitude was centrally mediated, since the in vitro response to LHRH of anterior pituitary fragments from P-implanted rats was the same as that of anterior pituitary fragments taken from rats with empty capsules. These studies demonstrate that the acute increase in LH pulse amplitude that occurs within 24 h after ovx on D1 is due to the absence of a central inhibitory effect of ovarian P, while the rapid increase in LH pulse frequency is due to the loss of both ovarian E and P.(ABSTRACT TRUNCATED AT 400 WORDS)
本研究的目的是确定在动情期第1天（D1）卵巢切除（ovx）后24小时内促黄体生成素（LH）脉冲幅度和频率的快速增加是否归因于孕酮（P）和/或雌二醇（E）的去除。初步研究表明，在我们的未切除卵巢的大鼠群体中，D1傍晚至D2早晨期间，E和P的血浆水平分别为18.2±1.2 pg/ml和34.1±3.2 ng/ml。在D1早晨进行ovx和颈静脉插管后，立即给大鼠植入空的硅橡胶胶囊或能够将E和P的生理水平恢复到上述对照值的胶囊。这些大鼠在ovx后1天连续采血（75微升/6分钟）3小时，用于分析LH的脉冲式释放，然后采集额外的血浆样本以测定E和P水平。植入空胶囊的大鼠E和P水平降低，平均血LH水平、LH脉冲幅度和脉冲频率增加。植入E胶囊的动物E水平处于生理状态，P水平降低，但未抑制ovx后LH脉冲式释放的急性增加。相比之下，植入P胶囊的动物血浆P水平处于生理状态，E水平降低，对ovx的急性LH反应明显降低。这种抑制完全是由于LH脉冲幅度降低，因为脉冲频率未改变。植入E和P胶囊的大鼠这些激素水平处于生理状态，这导致对ovx的急性LH反应进一步降低。这种抑制是由于LH脉冲幅度和脉冲频率均降低。P对LH脉冲幅度的作用是通过中枢介导的，因为植入P的大鼠垂体前叶片段对促性腺激素释放激素（LHRH）的体外反应与植入空胶囊的大鼠垂体前叶片段相同。这些研究表明，D1进行ovx后24小时内LH脉冲幅度的急性增加是由于卵巢P的中枢抑制作用缺失，而LH脉冲频率的快速增加是由于卵巢E和P均丧失。（摘要截取自400字）
