Cicero T J, Meyer E R, Gabriel S M, Bell R D, Wilcox C E
Brain Res. 1980 Nov 24;202(1):151-64.
Previous research has indicated that endogenous opioids participate in the regulation of activity in the hypothalamic-pituitary-luteinizing hormone (LH) axis and mediate the negative feedback control exerted by testosterone. If this assumption is correct, then two predictions can be made. First, the effects of testosterone should be competitively inhibited by narcotic antagonists; and, second, opiates should mimic the acute and chronic effects of testosterone in the castrated male rat. The results of the present investigations support both of these predictions. We found that naloxone competitively antagonized the depressive effects of testosterone on serum LH in the castrated rat and, conversely, that testosterone competitively antagonized the LH-releasing properties of naloxone. In addition, morphine and testosterone both depressed serum LH levels in a dose-dependent fashion in the acutely castrated animal. Moreover, morphine was just as effective as testosterone in reversing the castration-induced fall in hypothalamic-LH-releasing hormone (LH-RH), which occurs in the chronically castrated male rat. On the other hand, morphine failed to reverse the long-term changes in pituitary LH content and increase in serum LH, which is consistent with prior observations that morphine affects only the hypothalamic aspect of the hypothalamic-pituitary-LH axis in the male rat. These results, thus, support the concept that an as yet unidentified opioid-containing neuronal system regulates activity in the hypothalamic-pituitary-LH axis and mediates the effects of testosterone on this axis.
先前的研究表明，内源性阿片肽参与下丘脑 - 垂体 - 促黄体生成素（LH）轴的活动调节，并介导睾酮施加的负反馈控制。如果这一假设正确，那么可以做出两个预测。首先，睾酮的作用应被麻醉拮抗剂竞争性抑制；其次，阿片类药物应模拟去势雄性大鼠中睾酮的急性和慢性作用。本研究的结果支持了这两个预测。我们发现纳洛酮竞争性拮抗了睾酮对去势大鼠血清LH的抑制作用，反之，睾酮竞争性拮抗了纳洛酮的促LH释放特性。此外，吗啡和睾酮在急性去势动物中均以剂量依赖性方式降低血清LH水平。而且，在慢性去势雄性大鼠中，吗啡在逆转去势诱导的下丘脑促黄体生成素释放激素（LH - RH）下降方面与睾酮同样有效。另一方面，吗啡未能逆转垂体LH含量的长期变化以及血清LH的升高，这与先前的观察结果一致，即吗啡仅影响雄性大鼠下丘脑 - 垂体 - LH轴的下丘脑方面。因此，这些结果支持了这样一种概念，即一个尚未确定的含阿片肽神经元系统调节下丘脑 - 垂体 - LH轴的活动，并介导睾酮对该轴的作用。
