CELLULAR BASIS OF CIRCADIAN RHYTHMS IN MAMMALS

描述（由申请人提供）：哺乳动物视交叉上核（SCN）是行为和生理的日常循环所必需的。其他一些大脑区域，包括主嗅球（OB），也表达内在的昼夜节律。目前尚不清楚这些区域中的哪些细胞是如何同步并维持这些节律的，也不知道它们在行为中扮演什么角色。血管活性肠多肽（VIP）是SCN昼夜节律同步所必需的神经肽，也存在于其他昼夜节律组织的神经元中。关于VIP如何介导SCN内的同步，或者它是否协调大脑其他区域的节奏，人们知之甚少。拟议的研究通过利用长时间记录技术（多电极阵列和基因活性的生物发光报告器）以及涉及昼夜节律计时或转基因基因突变的小鼠的独特特性，直接解决了这些问题，这些基因突变允许在特定细胞类型中有条件地操纵基因表达和细胞活力。目的1测试VIP在各种脑区域和细胞类型中携带日常节律的假设。策略是比较vip诱导的3个脑区神经元和胶质细胞的急性和昼夜放电率以及基因表达模式的实时变化。此外，还将在体内研究VIP在OB和嗅觉中的作用。目的2验证了SCN中VIP神经元参与控制和维持昼夜运动节律的假设，以及OB中VIP神经元参与OB和嗅觉行为节律的假设。这项研究还测试了VIP神经元中的时钟基因是否对它们的节律性和这些行为节律至关重要。Aim 3使用相关的放电和基因表达模式以及药理学来绘制功能连接以及谷氨酸、一氧化氮和VIP在SCN内昼夜节律同步中的相对作用。最近在许多哺乳动物组织中发现了假定的昼夜节律振荡器，这导致了昼夜节律系统分层组织的假设，这种协调的破坏可能是包括抑郁症在内的各种神经系统疾病的基础。这些实验将首次确定协调大脑整体日常节奏的机制，以及它们在行为中扮演的独特角色。行为和情绪的日常节奏是由大脑中的生物钟驱动的。该项目研究了特定神经元和信号分子在大脑区域内和区域间神经活动和基因表达的昼夜节律调节以及运动和感觉功能中的作用。

DESCRIPTION (provided by applicant): The mammalian suprachiasmatic nucleus (SCN) is required for daily cycles in behavior and physiology. Some other brain regions, including the main olfactory bulb (OB), also express intrinsic circadian rhythms. It is not known how or which cells within these regions synchronize and sustain these rhythms or what role they play in behavior. The neuropeptide vasoactive intestinal polypeptide (VIP) is required for circadian synchrony in the SCN and is found in neurons of other circadian tissues. Little is known about how VIP mediates synchrony within the SCN or if it coordinates rhythms in other brain regions. The proposed studies directly address these issues by taking advantage of long-duration recording technologies--multielectrode arrays and bioluminescent reporters of gene activity--and the unique properties of mice with mutations in genes involved in circadian timekeeping or transgenes that allow conditional manipulation of gene expression and cell viability in specific cell types. Aim 1 tests the hypotheses that VIP entrains daily rhythms in variety of brain regions and cell types. The strategy is to compare VIP-induced changes in acute and circadian firing rate and gene expression patterns in real time of neurons and glia within 3 brain regions. In addition, the role of VIP in the OB and in olfaction will be assayed in vivo. Aim 2 tests the hypotheses that VIP neurons in the SCN are required to entrain and sustain circadian locomotor rhythms and that VIP neurons in the OB are required for rhythms in the OB and in olfactory behavior. This Aim also tests whether clock genes in VIP neurons are essential for their rhythmicity and for these rhythms in behavior. Aim 3 uses correlated firing and gene expression patterns and pharmacology to map functional connectivity and the relative roles of glutamate, nitric oxide and VIP in circadian synchrony within the SCN. The recent discoveries of putative circadian oscillators in many mammalian tissues have led to the hypothesis that the circadian system is hierarchically organized and that disruption of this coordination could underlie various neurological disorders including depression. These experiments will, for the first time, identify the mechanisms that coordinate ensemble daily rhythms in the brain and the distinct roles they play in behavior. Daily rhythms in behavior and mood are driven by circadian clocks in the brain. This project examines the role of specific neurons and signaling molecules in the circadian regulation of neural activity and gene expression in and between brain areas and in locomotor and sensory function.