伏隔核PV中间神经元调控睡眠觉醒的作用和机制

失眠已成为日益严重的社会和医学问题。焦虑性失眠最为常见，但机制不明。前额叶皮层、杏仁核和腹侧海马等焦虑相关核团投射至伏隔核并主要支配PV中间神经元；我们发现伏隔核中存在促睡眠和促觉醒两种投射神经元，均可被PV中间神经元支配；预实验显示，抑制伏隔核PV中间神经元显著增加睡眠。我们假说：焦虑相关核团通过调控伏隔核PV中间神经元，改变伏隔核中睡眠神经元活性，从而调控睡眠-觉醒时相转换和维持。本课题将采用PV-Cre小鼠和药理遗传学、光遗传学、选择性神经元损毁、在体光纤钙信号记录等方法，结合自动化睡眠觉醒解析平台和小鼠焦虑性失眠模型，研究伏隔核PV中间神经元的睡眠觉醒调控作用；用神经元逆向跨单突触追踪、免疫组化、膜片钳和光遗传学等技术，揭示其调控睡眠觉醒的神经环路和递质机制。预期结果将丰富和发展睡眠觉醒调控理论，为发现治疗焦虑性失眠有效靶点提供新思路。

Sleep remains one of the most mysterious animal behaviors known to science. To understand how sleep is regulated becomes a cutting-edge scientific issue, as in the modern society, more and more people are suffering from insomnia and other sleep disturbances. Accumulating evidence has uncovered the neural systems that regulate sleep-wake states in mammals and the homeostatic drive as well as the circadian rhythm that control the timing of sleep-wake state transition. In addition, it is evident that emotional and cognitive factors also influence sleep–wake behaviour. However, the precise circuit mechanisms underlying their effects on sleep-wake control are not clear. It is reported that brain regions related to emotion and cognition are preferentially connected with parvalbumin-expressing interneurons in the nucleus accumbens, a brain area critical for reward and motivated behavior. There are sleep-promoting and wake-promoting projecting neurons in the nucleus accumbens, and both of them are inhibited by PV interneurons. In addition, our preliminary data show that chemogenetic inhibition of nucleus accumbens PV interneurons induces sleep. Based on these facts, we hypothesize that emotional and cognitive input signals excite PV interneurons, and evoke feedforward inhibition in sleep-promoting projecting neurons in the nucleus accumbens, thus inducing wakefulness. And when the input signals reduce, the activities of the PV interneuron decrease, which causes disinhibition of sleep-promoting projecting neurons, thereby resulting in sleep. In the present study, we will use PV-Cre mice, optogenetics, pharmacogenetics and selective neuronal lesion to specifically manipulate the activity of PV interneurons, and in-vivo fiber photometry to record their population activity, and rabies virus-based cell type-specific retrograde tracing system to map and quantitatively analyze the whole-brain monosynaptic inputs to nucleus accumbens PV interneurons. Combined with automatic sleep bioassay systems, immunohistochemistry, patch-clamp recordings and other techniques, we will study the roles and neural circuits of nucleus accumbens PV interneurons in sleep-wake regulation. The outcome of the project will provide new insights into sleep-wake regulation by neurons in the nucleus accumbens, and will aid in the development of clinical treatment of insomnia caused by emotional and mental discomforts.