Ferland L, Borgeat P, Labrie F, Bernard J, De Lean A
Mol Cell Endocrinol. 1975 Jan;2(2):107-15. doi: 10.1016/0303-7207(75)90052-0.
The plasma LH (luteinizing hormone) response to 200 ng of LH-RH (LH-releasing hormone) injected subcutaneously at different stages of the estrous cycle in normal rats under Surital anesthisia was maximal during the afternoon of proestrus and lowest on diestrus I. The area under the plasma LH curve measured at 13:00 on proestrus was approximately 7-fold higher than that obtained at 15:30 h on diestrus I. Intermediate responses were found on diestrus II, estrus and morning of proestrus. An approsimately 2.5-fold higher LH response was observed on proestrus than on diestrus I after injection of [D-Ala2, des Gly-NH2-10] LH-RH ethylamide at 15:00 h. That these marked changes of LH response are not secondary to interference by endogenous LH-RH, changes of the metabolism or transport of exogenous LH-RH or modification of plasma LH clearance is ascertanied by the finding of similar changes of pituitary sensitivity to LH-RH under in vitro conditions using pituitaries collected at the same stag-s of the estrous cycle. As measured both in vivo and in vitro, not only the amplitude but also the speed of LH response are maximal during the afternoon of proestrus and minimal on diestrus I.
在速眠新麻醉下，正常大鼠在发情周期不同阶段皮下注射200 ng促黄体生成素释放激素（LH-RH）后，血浆促黄体生成素（LH）的反应在发情前期下午最大，在间情期I最低。发情前期13:00测得的血浆LH曲线下面积比间情期I 15:30时获得的面积高约7倍。在间情期II、发情期和发情前期早晨发现的反应介于两者之间。在15:00注射[D-丙氨酸2，去甘氨酰胺-10]LH-RH乙酰胺后，发情前期的LH反应比间情期I高约2.5倍。通过在体外条件下使用在发情周期相同阶段采集的垂体发现垂体对LH-RH的敏感性有类似变化，确定这些LH反应的显著变化不是内源性LH-RH干扰、外源性LH-RH代谢或转运变化或血浆LH清除率改变的继发结果。无论是在体内还是体外测量，LH反应的幅度和速度在发情前期下午都是最大的，在间情期I最小。
