大麻素系统通过DMH-PeF环路调控睡眠的神经机制研究

Approximately 1/5 of the population have chronic insomnia, which is a risk factor for depression, substance abuse, cognitive impairment, and cardiovascular diseases. To find the key circuits and targets for sleep modulation becomes one of the most crucial scientific problems. As an old drug, cannabinoids were used as a treatment for insomnia, because they were associated with a greater average improvement in sleep quality and sleep disturbance. However, the underlying neural mechanisms of sleep modulation by cannabinoids remain unknown. It is well established that cannabinoids activation of presynaptic type 1 cannabinoid receptor (CB1R), which distributes intensively in the hypothalamus, inhibits release of neurotransmitters from presynaptic axon terminals to regulate synaptic transmission reversely. Recent researches also showed that the expression of endocannabinoids and CB1R exhibit diurnal fluctuations in many brain regions, while type 2 cannabinoid receptor does not seem to undergo the fluctuations. Our preliminary experiments found that cannabinoids prominently prolong non-rapid eye movement sleep and shorten wakefulness, both of which are significantly inhibited by antagonizing CB1R in the perifornical area (PeF) and dorsomedial nucleus of the hypothalamus (DMH), but not ventral lateral preoptic area (VLPO). Therefore, we speculate that cannabinoids activation of presynaptic CB1R regulates the excitation of presynaptic neurons in the DMH and PeF, and result in modulation of the DMH-PeF circuitry and sleep improvement. Focused on the underlying neural networks and their cellular constituents, wireless sleep recording and analysis system, mutant mice, chemogenetics and optogenetics will be used in this study to investigate how DMH-PeF circuitry were regulated by cananbinoids for sleep modulation. The present study is aimed to provide novel evidence and insights on the neural mechanisms of cannabinoids for sleep modulation, and represent a promising therapeutic target for treatment of chronic insomnia.

大麻素作为古老的药物，可显著改善睡眠质量，减少失眠症发病，但其神经机制仍是未解之谜。已知大麻素可通过1型大麻素受体（CB1R）抑制突触前递质释放进行逆向信号调控，而内源性大麻素和CB1R的表达均具有昼夜节律性，且CB1R集中分布于下丘脑。我们预实验发现大麻素可显著延长非快动眼睡眠，减少觉醒，而在下丘脑的DMH（节律调控）和PeF（促觉醒）核团注射CB1R拮抗剂则可逆转该作用。由此我们推测大麻素可通过下丘脑DMH和PeF核团中的CB1R，逆向调节突触前神经元的兴奋性，进而通过DMH-PeF神经环路促进睡眠。本项目将应用多种模式动物、睡眠监测系统、化学遗传学、光遗传学等技术，以神经环路及其细胞组成研究为核心，进一步探索大麻素系统通过下丘脑DMH-PeF神经通路促进睡眠的神经机制，从而为揭示大麻素系统的睡眠调控机制提供重要的实验依据和理论基础，也为睡眠治疗提供新的治疗靶点和药物备选。

大麻素作为古老的药物，可显著改善睡眠质量，减少失眠症发病，但其神经机制仍是未解之谜。已知大麻素可通过1型大麻素受体（CB1R）抑制突触前递质释放进行逆向信号调控，而内源性大麻素和CB1R的表达均具有昼夜节律性，且CB1R集中分布于下丘脑。我们推测大麻素可通过下丘脑背内侧核（DMH）和穹窿周围核（PeF）的CB1R，逆向调节突触前神经元的兴奋性，通过DMH-PeF神经环路促进睡眠。本项目应用多种模式动物、睡眠监测系统、化学遗传学、光遗传学等技术，发现①外源性大麻素可长时间促进非快动眼睡眠（NREM），抑制觉醒和快动眼睡眠（REM），并影响睡眠结构；②明确了大麻素的促睡眠效应是通过CB1R，尤其是DMH和PeF核团内的CB1R，而非腹外侧视前区（VLPO）发挥作用的；③证实了CB1R通过调控DMH的兴奋性突触前活动，影响DMH核团内谷氨酸能神经元的兴奋性调控睡眠；④验证了大麻素通过调控兴奋性DMH-PeF投射发挥促睡眠作用；⑤发现了DMH突触前兴奋性投射来自于前额叶皮质（mPFC），进一步证实了mPFC-DMH-PeF三级环路是主动调控NREM睡眠与觉醒的关键环路。上述结果初步揭示了大麻素调控睡眠的mPFC-DMH-PeF神经环路机制，部分明确了其细胞特异性，不仅为进一步明确睡眠主动调控的top-down机制提供了重要的实验依据和理论基础，也为睡眠治疗提供新的治疗靶点和药物备选。相关发表SCI论文3篇，在投SCI论文一篇；获教育部科技进步一等奖1项；申请发明专利一项，获批实用新型专利4项；培养硕士研究生2名（毕业1名），博士研究生2名，指导博士研究生在中国药理学会麻醉药理学专业委员会第十一次全国学术会议暨第二届临床药理学与治疗学高峰论坛”青年学者论坛中获特等论文报告。