Role of VIP-expressing SCN neurons in circadian physiology and behavior

 描述（由申请人提供）：视交叉上核（SCN）是哺乳动物大脑中的主要昼夜节律起搏器。 它产生强大的昼夜节律行为，夹带到环境线索，如光输入。 到目前为止，很少有人知道SCN神经元的放电如何整合输入并在昼夜节律行为中产生连贯的输出节律，如唤醒/睡眠，激素水平，新陈代谢和情绪。 SCN是由不同群体的遗传不同的神经元，包括血管活性肠多肽（VIP）表达神经元。 该提案旨在了解SCN VIP表达神经元的神经代码如何改变放电率，昼夜节律基因表达和运动行为。 我将确定VIP SCN神经元的神经密码，并使用光遗传学和药理学操作来测试不同神经递质信号通路的作用。 具体地说，我将确定特征VIP在早期主观天（目的I。 使用这些模式，我可以刺激VIP神经元和测试SCN放电活动（Aim II），昼夜节律基因表达（Aim III）和运动行为（Aim IV）的变化。 此外，药理学拮抗剂的使用将使我能够解析出VIP和GABA在这些双递质表达神经元中的作用。 我的初步数据确立了这些方法的可行性;我证明了ChR 2可以在VIP SCN神经元内选择性表达，刺激可以在生理相关频率下产生动作电位，15 Hz 30 min刺激可能导致基因表达同步性降低和运动行为片段化。 总的来说，这个提议通过回答关于VIP神经元中的内源性神经代码如何维持昼夜节律同步和输出的关键问题，扩展了我目前的研究。 这是一个重要的建议，因为结果可以帮助理解与神经系统疾病，衰老和时差相关的昼夜节律紊乱。

 DESCRIPTION (provided by applicant): The suprachiasmatic nucleus (SCN) is the master circadian pacemaker in the mammalian brain. It generates robust circadian behaviors, entrained to environmental cues such as light input. To date, little is known about how firing from SCN neurons integrates input and generates coherent output rhythms in circadian behaviors such as wake/sleep, hormone levels, metabolism, and mood. The SCN is composed of various populations of genetically distinct neurons including vasoactive intestinal polypeptide (VIP) - expressing neurons. This proposal aims to understand how the neural code from VIP-expressing neurons of the SCN alters firing rate, circadian gene expression and locomotor behavior. I will identify the neural code of VIP SCN neurons and use optogenetic and pharmacological manipulations to test the role of distinct neurotransmitter signaling pathways. Specifically, I will identify characteristic VIP firing patterns during early subjective day (Aim I. Using these patterns, I can stimulate VIP neurons and test changes in SCN firing activity (Aim II), circadian gene expression (Aim III) and locomotor behavior (Aim IV). In addition, the use of pharmacological antagonists will allow me to parse out the role of VIP and GABA in these dual-transmitter expressing neurons. My preliminary data establishes the feasibility of these approaches; I demonstrated that ChR2 can be selectively expressed within VIP SCN neurons, stimulation can generate action potentials at physiologically relevant frequencies, and 15Hz 30min stimulation may cause decreases in gene expression synchrony and fragmentation of locomotor behavior. Overall, this proposal expands on my current research by answering key questions about how the endogenous neural code in VIP neurons sustains circadian synchrony and output. This is an important proposal because the results can help understand circadian disruption associated with neurological disorders, aging, and jet lag.