Petterborg L J, Rudeen P K
Department of Anatomy, School of Medicine, University of Missouri, Columbia 65212.
J Pineal Res. 1989;6(4):367-73. doi: 10.1111/j.1600-079x.1989.tb00433.x.
Female hamsters were treated each afternoon for 8 weeks with subcutaneous injections of 25 micrograms of either melatonin or vehicle solution. Animals were sacrificed in either the morning or afternoon of diestrus and proestrus, along with their respective melatonin-induced acyclic pairs. Melatonin-treated hamsters had significantly greater mean body weights than did the vehicle-treated hamsters (P less than 0.05). Terminal mean serum T4 levels and free thyroxine index (FT41) were significantly reduced (P less than 0.05) in melatonin-treated hamsters compared with values obtained from animals subjected to the vehicle alone. In addition, T4 levels, FT41, T3 levels, and FT31 were significantly influenced by day and time of sacrifice independently of the melatonin treatment. T3 uptake was significantly lower on the morning of proestrus in melatonin-treated animals. These results demonstrate that chronic afternoon melatonin administration in female hamsters results in the loss of estrous cyclicity, a significant gain in body weight, and the reduction of T4 levels and T3 uptake. Changes in serum T3 levels are a function of the time of sample collection and are not influenced by melatonin treatment. In addition, these data indicate that thyroid function in general changes during the estrous cycle in these animals.
雌性仓鼠每天下午接受皮下注射25微克褪黑素或溶剂溶液，持续8周。在动情间期和动情前期的上午或下午处死动物，同时处死各自经褪黑素诱导的无发情周期配对动物。与接受溶剂处理的仓鼠相比，接受褪黑素处理的仓鼠平均体重显著更高（P<0.05）。与仅接受溶剂处理的动物相比，接受褪黑素处理的仓鼠终末平均血清T4水平和游离甲状腺素指数（FT4I）显著降低（P<0.05）。此外，T4水平、FT4I、T3水平和FT3I受处死日期和时间的显著影响，与褪黑素处理无关。在接受褪黑素处理的动物中，动情前期上午的T3摄取显著降低。这些结果表明，雌性仓鼠长期下午给予褪黑素会导致发情周期丧失、体重显著增加以及T4水平和T3摄取降低。血清T3水平的变化是样本采集时间的函数，不受褪黑素处理的影响。此外，这些数据表明这些动物的甲状腺功能在发情周期中总体上会发生变化。
