自感光神经节细胞—腹外侧视前区通路参与睡眠与觉醒调节的机制

Sleep is affected by light illumination and darkness. These are several evidences showing that, intrinsically photosensitive retinal ganglion cells (ipRGCs), which contain melanopsin, directly project to the ventrolateral preoptic area (VLPO), a sleep promotion center, and modify the sleep state. Our preliminary experiments further demonstrated that ipRGCs make synapses with VLPO neurons in mice. We hypothesized that ipRGCs are involved in regulating sleep and wakefulness by mediating light signal excitation VLPO sleep-promoting neurons. In the present study, we are going to use transgenic mice to observe the effect of different light conditions on their electroencephalographs and behaviors, or using optogenetic controlling the ipRGCs activity, to confirm the modulation effect of ipRGCs on sleep. On the other hand, patch clamp recording of VLPO brain slice combined with pharmacological analysis will be used to detect synaptic contact characteristics between ipRGCs and VLPO neurons. On these bases, pharmacological controlling the neuron activity in vivo will be used to explore the effect of the ipRGCs-VLPO pathway on the regulation of sleep and wakefulness. These studies will be expected to uncover the functional mechanism of ipRGCs to regulate sleep and wakefulness via exciting the sleep-promoting neurons of VLPO, and furthermore provide a scientific basis for the treatment of sleep disorder and related drug development.

睡眠状态可以为光、暗所调制。已有证据提示，视网膜包含光敏色素的自感光神经节细胞（ipRGC）与促睡眠中枢下丘脑腹外侧视前区（VLPO）间存在直接投射并调制睡眠；我们预实验结果显示，ipRGC与VLPO存在直接的兴奋性突触联系，结合研究进展，我们假说：小鼠ipRGC通过介导光信号兴奋VLPO内促睡眠神经元参与调节睡眠与觉醒的调节。本课题拟用转基因小鼠，采用脑电记录观察不同光强对小鼠脑电和行为的影响，或是利用光遗传学在体控制ipRGC活性，确认ipRGC对睡眠的调制作用；另一方面在离体小鼠脑片，通过膜片钳结合药理学等方法探究ipRGC-VLPO通路突触传递特性。在此基础上应用药理学在体控制神经元活性法，进一步研究ipRGC如何通过调制VLPO神经元活动影响睡眠-觉醒的机制。本研究将进一步揭示ipRGC-VLPO通路在睡眠-觉醒中的调节机制，也为临床治疗睡眠障碍和相关药物开发提供科学依据。

腹外侧视前核(VLPO)是重要的促睡眠中枢，包含两种类型的神经元，促进睡眠的神经元和中间神经元。早期研究表明去甲肾上腺素(NA)可增加或降低VLPO神经元动作电位频率，但其机制尚不清楚。前人研究表明，视网膜ipRGC对VLPO有投射，且ipRGC可能通过VLPO参与光诱导睡眠的调控，因此，我们进行了以下实验。首先，在多种转基因小鼠中利用脑电睡眠记录实验，结果显示ipRGC参与光诱导睡眠。其次，在转基因小鼠中利用全细胞膜片钳和光遗传技术，发现ipRGC可以兴奋促睡眠神经元。最后，在野生型小鼠中利用全细胞膜片钳技术，我们研究了NA对VLPO神经元兴奋或抑制作用的机制。NMDA受体拮抗剂(AP5)能阻断NA对中间神经元的兴奋作用，但不能阻断NA对促睡眠神经元的抑制作用。AMPA受体和GABA受体拮抗剂均不影响NA对VLPO神经元的作用。这些结果表明，NA对VLPO中间神经元的兴奋作用是是由NMDA受体介导的。