Role of orexin system in coordinating ultradian rhythm

本研究的目的是探索协调超昼夜节律的脑系统，重点研究促进觉醒的重要神经肽食欲素。该项目研究了具有食欲素或食欲素神经元缺陷的转基因小鼠的超日模式。在野生型中，体温和产热率在大约每90分钟时间歇性增加，证实了小鼠和大鼠中存在超日节律。在食欲素相关的转基因小鼠中，体温和自发活动的超日增加幅度显著降低。该项目还采用了光遗传学修饰的小鼠，其中食欲素神经元活性可以通过聚焦光照明来控制。食欲素神经元的长期激活减弱了超日节律的幅度。这些数据表明，食欲素系统是重要的协调超日节律的体温和运动活动。

The aim of the present project is to explore brain system that coordinates the ultradian rhythm, focusing orexin, a neuropeptide that is important to promote wakefulness. The project investigated ultradian pattern in genetically-modified mice that have a deficient of orexin or of orexin neurons. In the wild type, body temperature and heat rate increased episodically at every approximately 90 min, confirming the existence of the ultradian rhythm in mice as with rats. In orexin-related transgenic mice, the amplitude of ultradian increase in body temperature and locomotor activity was significantly reduced. The project also employed optogenetically-modified mice in which orexin neuronal activity can be controlled by focal light illumination. Long lasting activation of orexin neurons attenuated the amplitude of the ultradian rhythm. These data suggest that orexin system is important for coordinating ultradian rhythm in body temperature and locomotor activity.