Yamashita K, Mieno M, Shimizu T, Yamashita E
J Endocrinol. 1978 Mar;76(3):487-91. doi: 10.1677/joe.0.0760487.
The rate of secretion of 17-oxosteroids by the testes of anaesthetized dogs in vivo was used as an index of LH secretion. Intracarotid injection of luteinizing hormone releasing hormone (LH-RH, 1, 5 or 10 microgram/kg body wt) resulted in an increase in the testicular 17-oxosteroid secretion which was roughly proportional to the dose administered and which reached a maximum 60 min after the injection. Testicular output of 17-oxosteroids was unaffected by administration of melatonin (10 or 100 microgram/kg body wt) into the carotid artery. When LH-RH (5 microgram/kg) was injected into the carotid artery 3 h after intracarotid injection of melatonin (10 or 100 microgram/kg), the testicular response to LH-RH was considerably diminished. Pretreatment with melatonin (100 microgram/kg) did not alter the testicular response to human chorionic gonadotrophin (20 i.u./kg body wt) given i.v. Is is concluded that melatonin may act directly on the anterior pituitary gland in dogs to inhibit the LH-RH-induced release of LH.
用麻醉犬体内睾丸分泌17 - 氧类固醇的速率作为促黄体生成素（LH）分泌的指标。颈动脉内注射促黄体生成素释放激素（LH - RH，1、5或10微克/千克体重）导致睾丸17 - 氧类固醇分泌增加，其增加量大致与给药剂量成正比，且在注射后60分钟达到最大值。向颈动脉内注射褪黑素（10或100微克/千克体重）对睾丸17 - 氧类固醇的分泌量没有影响。在颈动脉内注射褪黑素（10或100微克/千克体重）3小时后，再向颈动脉内注射LH - RH（5微克/千克），睾丸对LH - RH的反应明显减弱。用褪黑素（100微克/千克）预处理并没有改变睾丸对静脉注射人绒毛膜促性腺激素（20国际单位/千克体重）的反应。得出的结论是，褪黑素可能直接作用于犬的垂体前叶，以抑制LH - RH诱导的LH释放。
