Reductions in hamster serum thyroxine levels by melatonin are not altered by changes in serum testosterone
Reductions in hamster serum thyroxine levels by melatonin are not altered by changes in serum testosterone
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DOI：
10.1006/gcen.2001.7665
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发表时间：
2001-08-01
影响因子：
2.7
通讯作者：
Champney, TH
中科院分区：
文献类型：
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作者：
Champney, TH
每天注射褪黑激素会降低雄性叙利亚仓鼠的生殖激素和甲状腺激素。这些激素下降之间的相互关系尚不清楚。为了探索这种关系，雄性叙利亚仓鼠被分为四组：去势，植入睾酮（5毫米硅橡胶植入物），两种治疗，或没有治疗。每天17：30时，每组仓鼠的一半（n = 7或8）注射褪黑激素（25 mg）。每组的另一半每天接受溶媒注射。10周后，将仓鼠麻醉并斩首。测量睾丸重量、血清睾酮和血清甲状腺素水平。正如预期的那样，在所有褪黑激素处理的仓鼠中，睾丸和血清睾酮水平一致较低。所有的褪黑激素治疗组也低于正常的甲状腺素值，无论性腺治疗。有趣的是，在非褪黑激素处理的仓鼠中，血清甲状腺素值在去势组中降低，而在睾酮植入组中升高。这些结果表明，阉割可以降低血清甲状腺素水平在雄性叙利亚仓鼠和睾酮的替代恢复这些水平正常。值得注意的是，每天注射褪黑激素所产生的甲状腺素水平下降并没有被去势或完整仓鼠的睾酮植入所恢复。因此，褪黑激素诱导的甲状腺素减少并不通过同时降低血清睾酮水平来介导。看来褪黑激素诱导的血清甲状腺素水平降低与去势诱导的降低不使用相同的机制。(C)北京：科学出版社.
Daily melatonin injections reduce reproductive and thyroid hormones in male Syrian hamsters. The interrelationship between the decline in these hormones is not known. To explore this relationship, male Syrian hamsters were divided into four groups: castrated, implanted with testosterone (5-mm silastic implants), both treatments, or neither treatment. One-half of each group of hamsters (n = 7 or 8) were injected with melatonin (25 mg) daily at 1730 h. The other half of each group received daily vehicle injections. Ten weeks later, the hamsters were anesthetized and decapitated. Testes weights, serum testosterone, and serum thyroxine levels were measured. As expected, testes and serum testosterone levels were uniformly low in all of the melatonin-treated hamsters. All of the melatonin-treated groups also had lower than normal thyroxine values irrespective of gonadal treatment. Interestingly, in the non-melatonin-treated hamsters, serum thyroxine values were decreased in the castrated group and increased in the testosterone-implanted group. These results suggest that castration can reduce serum thyroxine levels in male Syrian hamsters and that replacement of testosterone restores these levels to normal. Notably, the declines in thyroxine levels produced by daily melatonin injections were not restored by testosterone implants in castrated or intact hamsters. Therefore, melatonin-induced reductions in thyroxine are not mediated by concurrent reductions in serum testosterone levels. It appears that melatonin-induced reductions in serum thyroxine levels do not use the same mechanism as castration-induced reductions. (C) 2001 Academic Press.