Juniewicz P E, Johnson B H, Bolt D J
J Androl. 1987 May-Jun;8(3):190-6. doi: 10.1002/j.1939-4640.1987.tb02430.x.
The effects of adrenal steroids on testosterone and LH secretion and changes in serum cortisol levels in response to treatments were studied in the ram. Acute administration of synthetic ACTH (10 micrograms/kg BW) elevated (P less than 0.01) serum cortisol and transiently suppressed (P less than 0.05) serum testosterone and LH. Acute dexamethasone treatment suppressed (P less than 0.01) serum cortisol, testosterone and LH. Administration of vehicle had no effect (P greater than 0.10) on serum hormone levels. These data support the contention that adrenal steroids inhibit testicular endocrine function indirectly by acting at the hypothalamic or pituitary level because both ACTH and dexamethasone treatments suppressed serum LH. To differentiate between hypothalamic and pituitary sites of action, the pituitary and testicular responses to an LHRH challenge (100 micrograms) were examined in rams chronically treated with dexamethasone (5 mg i.m., twice daily for 5 days). This treatment regimen suppressed (P less than 0.01) serum cortisol levels. Compared with controls, basal testosterone levels were suppressed (P less than 0.05) in dexamethasone-treated rams; however, no effect (P greater than 0.10) on the magnitude of the testosterone response to LHRH or on either basal or LHRH-stimulated LH secretion was observed. Thus, although a direct testicular effect cannot be eliminated, these data suggest that, in the ram, adrenal steroids inhibit testicular endocrine function by action at the level of the hypothalamus.
研究了肾上腺类固醇对雄性绵羊睾酮和促黄体生成素（LH）分泌的影响，以及处理后血清皮质醇水平的变化。急性注射合成促肾上腺皮质激素（ACTH，10微克/千克体重）可使血清皮质醇升高（P<0.01），并短暂抑制（P<0.05）血清睾酮和LH。急性地塞米松处理可抑制（P<0.01）血清皮质醇、睾酮和LH。注射赋形剂对血清激素水平无影响（P>0.10）。这些数据支持肾上腺类固醇通过作用于下丘脑或垂体水平间接抑制睾丸内分泌功能的观点，因为ACTH和地塞米松处理均抑制了血清LH。为了区分下丘脑和垂体的作用位点，在长期用地塞米松（5毫克，肌肉注射，每日两次，共5天）处理的雄性绵羊中，检测了垂体和睾丸对促性腺激素释放激素（LHRH，100微克）刺激的反应。这种处理方案可抑制（P<0.01）血清皮质醇水平。与对照组相比，地塞米松处理的雄性绵羊基础睾酮水平受到抑制（P<0.05）；然而，未观察到对睾酮对LHRH反应幅度或基础及LHRH刺激的LH分泌有影响（P>0.10）。因此，尽管不能排除对睾丸的直接作用，但这些数据表明，在雄性绵羊中，肾上腺类固醇通过作用于下丘脑水平抑制睾丸内分泌功能。
