Sleep and Melatonin in Diurnal and Nocturnal Rodents

大量研究表明，褪黑素可以诱导人类睡眠。然而，造成这种影响的大脑机制尚不清楚。这是由于缺乏实验室啮齿动物模型的褪黑激素的催眠作用；用褪黑素诱导实验室啮齿动物睡眠的尝试是用夜间活动的啮齿动物，即在周期的黑暗阶段活动的啮齿动物，如老鼠和保加利亚仓鼠。褪黑素在这些啮齿动物中并不能持续诱导睡眠。事实上，在大多数研究中，褪黑素减少了睡眠，增加了清醒。因为这些夜行动物在夜间最活跃，此时褪黑素分泌最高，所以这些结果不应该令人惊讶。需要一个昼夜活动的啮齿动物模型来证明褪黑激素的睡眠诱导作用。无条纹尼罗河草鼠（Arvicanthis niloticus，无条纹尼罗河草鼠）是一种昼行性啮齿类动物，是证明褪黑素诱导睡眠作用的理想动物。此外，利用这种啮齿动物作为模型，可以研究褪黑素诱导睡眠的大脑回路。这些研究的结果可能阐明褪黑素如何用于治疗失眠和失眠

Numerous studies have shown that melatonin can induce sleep in humans. However, the brain mechanisms responsible for this effect are unknown. This is due to the lack of a laboratory rodent model of the soporific effects of melatonin; attempts to induce sleep with melatonin in laboratory rodents have used nocturnal rodents, meaning rodents active during the dark phase of the cycle, such as rats and Djungarian hamsters. Melatonin does not consistently induce sleep in these rodents. In fact, in most of these studies, melatonin reduced sleep and increased wakefulness. Because these nocturnal animals are most active during the night, when melatonin secretion is the highest, these results should not be surprising. A diurnal rodent model is needed to demonstrate the sleep-inducing effects of melatonin. Arvicanthis niloticus (unstriped Nile grass rat), a diurnal murid rodent, is an ideal animal in which to demonstrate the sleep-inducing effects of melatonin. Further, using this rodent as a model, the brain circuitry through which melatonin induces sleep can be investigated. Results from these studies may clarify how melatonin can be used to treat insomnia and