Tamarkin L, Westrom W K, Hamill A I, Goldman B D
Endocrinology. 1976 Dec;99(6):1534-41. doi: 10.1210/endo-99-6-1534.
Hamsters were maintained on a long photoperiod (14L:10D) and were injected once daily with melatonin (10-25 mug) or sesame oil. Males which received melatonin during the afternoon (e.g., 6.5-13.75 h after lights-on) showed regressed testes and decreased levels of serum LH and FSH after several weeks of treatment. Injections of the oil vehicle or injections of melatonin given in the morning (3 h after lights-on) had no detectable effect on testicular size or on serum gonadotropins. Females which received melatonin during the afternoon became acyclic after several weeks of treatment and showed a diurnal pattern of LH secretion. The acyclic females required 4-6 weeks to resume estrous cyclicity following termination of the melatonin injections. The effects of melatonin on gonadal function and on serum gonadotropin concentrations in both sexes were similar to the previously observed effects of prolonged exposure to short photoperiods. These results indicate that chronic daily injections of melatonin can depress reproductive function in hamsters and that the effectiveness of the injections is dependent upon the time of day at which they are administered.
将仓鼠饲养在长光照周期（14小时光照：10小时黑暗）条件下，每天注射一次褪黑素（10 - 25微克）或芝麻油。在下午接受褪黑素注射的雄性仓鼠（例如，开灯后6.5 - 13.75小时），经过几周治疗后，睾丸萎缩，血清促黄体生成素（LH）和促卵泡生成素（FSH）水平降低。注射油剂载体或在早晨（开灯后3小时）注射褪黑素对睾丸大小或血清促性腺激素没有可检测到的影响。在下午接受褪黑素注射的雌性仓鼠，经过几周治疗后停止发情周期，并表现出促黄体生成素分泌的昼夜模式。停止注射褪黑素后，这些停止发情周期的雌性仓鼠需要4 - 6周才能恢复发情周期。褪黑素对两性性腺功能和血清促性腺激素浓度的影响与之前观察到的长期暴露于短光照周期的影响相似。这些结果表明，每天慢性注射褪黑素会抑制仓鼠的生殖功能，并且注射的有效性取决于给药的时间。
