Joshi B N, Vaughan M K, Nürnberger F, Reiter R J
Department of Cellular and Structural Biology, University of Texas Health Science Center, San Antonio 78284.
Chronobiol Int. 1985;2(1):47-54. doi: 10.3109/07420528509055541.
Two different experimental models were used to test if a temporal relationship exists between the rhythm of adrenal steroid secretion and the vulnerability of the hamster reproductive system to short photoperiod exposure or to the daily afternoon injection of melatonin. In the first experiment adrenalectomized hamsters were implanted with a cortisol pellet to provide a sustained, rather than rhythmic, level of the hormone. The animals were either placed in short photoperiod or given a daily afternoon melatonin injection. In both cases the gonads underwent atrophy. In the second experiment adrenalectomized hamsters were given a cortisol injection either in the morning (approx. 8 hr before the subsequent afternoon injection of melatonin) or in the afternoon (approx. 1 hr before the subsequent melatonin injection). Measurements of testicular and accessory organ weights 7 weeks later indicated regression of the reproductive system in both the groups when compared with their appropriate controls. Depressed levels of plasma LH, PRL, testosterone and thyroxine (T4) in these animals confirmed the melatonin induced gonadal collapse. The results suggest that apparently there is no temporal correlation between the rhythm of secretion of the adrenal steroids and the responsiveness of the reproductive system to late afternoon injection of melatonin. Interestingly, all the adrenalectomized cortisol injected control animals (not receiving melatonin) had depressed plasma LH and PRL while the testicular weights and plasma testosterone titers remain unaffected.
使用了两种不同的实验模型来测试肾上腺类固醇分泌节律与仓鼠生殖系统对短光周期暴露或每日下午注射褪黑素的易感性之间是否存在时间关系。在第一个实验中，对肾上腺切除的仓鼠植入皮质醇丸剂，以提供持续而非有节律的激素水平。将动物置于短光周期中或每日下午注射褪黑素。在这两种情况下，性腺均发生萎缩。在第二个实验中，对肾上腺切除的仓鼠在上午（约在随后下午注射褪黑素前8小时）或下午（约在随后注射褪黑素前1小时）注射皮质醇。7周后对睾丸和附属器官重量的测量表明，与各自的适当对照组相比，两组的生殖系统均出现退化。这些动物血浆中促黄体生成素（LH）、催乳素（PRL）、睾酮和甲状腺素（T4）水平降低证实了褪黑素诱导的性腺萎缩。结果表明，肾上腺类固醇分泌节律与生殖系统对下午晚些时候注射褪黑素的反应性之间显然不存在时间相关性。有趣的是，所有注射皮质醇的肾上腺切除对照动物（未接受褪黑素）血浆LH和PRL均降低，而睾丸重量和血浆睾酮水平未受影响。
