Tsunematsu Tomomi
Graduate School of Life Sciences, Tohoku University, Sendai, Japan.
Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai, Japan.
Adv Exp Med Biol. 2021;1293:391-406. doi: 10.1007/978-981-15-8763-4_25.
Although sleep is an absolutely essential physiological phenomenon for maintaining normal health in animals, little is known about its function to date. In this section, I introduce the application of optogenetics to freely behaving animals for the purpose of characterizing neural circuits involved in the regulation of sleep/wakefulness. Applying optogenetics to the specific neurons involved in sleep/wakefulness regulation enabled the precise control of the sleep/wakefulness states between wakefulness, non-rapid eye movement (NREM) sleep, and REM sleep states. For example, selective activation of orexin neurons using channelrhodopsin-2 and melanopsin induced a transition from sleep to wakefulness. In contrast, suppression of these neurons using halorhodopsin and archaerhodopsin induced a transition from wakefulness to NREM sleep and increased the time spent in NREM sleep. Selective activation of melanin-concentrating hormone (MCH) neurons induced a transition from NREM sleep to REM sleep and prolonged the time spent in REM sleep, which was accompanied by a decrease in NREM sleep time. Optogenetics was first introduced to orexin neurons in 2007 and has since rapidly spread throughout the field of neuroscience. In the last 13 years or so, neural nuclei and the cell types that control sleep/wakefulness have been identified. The use of optogenetic studies has greatly contributed to the elucidation of the neural circuits involved in the regulation of sleep/wakefulness.
尽管睡眠对于维持动物的正常健康而言是一种绝对必要的生理现象，但迄今为止人们对其功能仍知之甚少。在本节中，我将介绍光遗传学在自由活动动物中的应用，目的是表征参与睡眠/觉醒调节的神经回路。将光遗传学应用于参与睡眠/觉醒调节的特定神经元，能够精确控制清醒、非快速眼动（NREM）睡眠和快速眼动（REM）睡眠状态之间的睡眠/觉醒状态。例如，使用通道视紫红质-2和黑视蛋白对食欲素神经元进行选择性激活会诱导从睡眠到清醒的转变。相反，使用嗜盐视紫红质和古紫质对这些神经元进行抑制会诱导从清醒到NREM睡眠的转变，并增加在NREM睡眠中花费的时间。对促黑素（MCH）神经元进行选择性激活会诱导从NREM睡眠到REM睡眠的转变，并延长在REM睡眠中花费的时间，同时NREM睡眠时间会减少。光遗传学于2007年首次应用于食欲素神经元，此后迅速在神经科学领域传播开来。在过去约13年中，已经确定了控制睡眠/觉醒的神经核团和细胞类型。光遗传学研究的应用对阐明参与睡眠/觉醒调节的神经回路做出了巨大贡献。
