Mann D R, Free C, Nelson C, Scott C, Collins D C
Endocrinology. 1987 Apr;120(4):1542-50. doi: 10.1210/endo-120-4-1542.
In this study, we examined the effect of ACTH on the sensitivity of the testes to gonadotropin and determined the role of the testosterone (T) negative feedback system in mediating the inhibitory effect of ACTH on LH secretion in adult male rats. ACTH infusion for 3 days reduced basal levels of serum T and the T response to GnRH, but did not alter basal levels of serum LH (immunoreactive) or the LH response to GnRH. These effects required the presence of the adrenal glands. Infusion of corticosterone (B) at a dose that increased serum B concentrations 9-fold had an effect similar to that of ACTH on basal serum T levels and the serum T response to GnRH. Basal levels of serum LH and the serum LH response to GnRH were not affected by B administration. These data suggest that ACTH administration reduces the sensitivity of the testes to LH, resulting in a lower basal level of T and a reduced T response to GnRH. This effect was independent of basal serum LH levels or the LH response to GnRH. It appears that B mediates the effect of ACTH on testicular sensitivity to gonadotropin. In another experiment, ACTH administration for 4 days did not alter serum LH values, but reduced serum T levels in sham-castrated male rats. In contrast, ACTH treatment blunted the increase in serum LH after castration by day 2 of treatment, despite the absence of detectable levels of serum T within 6 h after castration. These data suggest that T is not essential for the inhibitory effect of ACTH on LH secretion to occur. They do not support the hypothesis that ACTH enhances the sensitivity of the hypothalamus and/or pituitary to the negative feedback effects of T.
在本研究中，我们检测了促肾上腺皮质激素（ACTH）对睾丸对促性腺激素敏感性的影响，并确定了睾酮（T）负反馈系统在介导ACTH对成年雄性大鼠促黄体生成素（LH）分泌的抑制作用中的作用。连续3天输注ACTH可降低血清T的基础水平以及T对促性腺激素释放激素（GnRH）的反应，但未改变血清LH（免疫反应性）的基础水平或LH对GnRH的反应。这些作用需要肾上腺的存在。以能使血清皮质酮（B）浓度增加9倍的剂量输注皮质酮，其对基础血清T水平和血清T对GnRH反应的影响与ACTH相似。血清LH的基础水平以及血清LH对GnRH的反应不受B给药的影响。这些数据表明，给予ACTH会降低睾丸对LH的敏感性，导致T的基础水平降低以及T对GnRH的反应减弱。这种作用与基础血清LH水平或LH对GnRH的反应无关。似乎B介导了ACTH对睾丸对促性腺激素敏感性的影响。在另一项实验中，对假去势雄性大鼠连续4天给予ACTH未改变血清LH值，但降低了血清T水平。相反，尽管去势后6小时内血清T检测不到，但ACTH治疗在治疗第2天就减弱了去势后血清LH的升高。这些数据表明，T对于ACTH抑制LH分泌的作用并非必不可少。它们不支持ACTH增强下丘脑和/或垂体对T负反馈作用敏感性的假说。
