CELLULAR BASIS OF CIRCADIAN RHYTHMS IN MAMMALS

描述(申请人提供)：哺乳动物视交叉上核(SCN)是日常行为和生理周期所必需的。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内的哪些细胞或如何同步并维持这些节律，也不知道它们在行为中扮演什么角色。神经肽血管活性肠多肽(VIP)是SCN昼夜节律同步所必需的，在其他昼夜节律组织的神经元中也发现了VIP。关于血管活性肠肽如何在丘脑中央核内调节同步性，以及它是否协调其他脑区的节律，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动的生物发光报告器--以及涉及昼夜计时或转基因的基因突变的小鼠的独特特性直接解决这些问题，这些基因突变允许对特定细胞类型中的基因表达和细胞存活进行有条件的操作。目的1验证血管活性肠肽在不同脑区和细胞类型中参与日常节律的假说。该策略是比较VIP诱导的急性和昼夜放电频率的变化，以及实时的神经元和胶质细胞在3个脑区的基因表达模式。此外，VIP在OB和嗅觉中的作用将在体内进行测试。目的2验证如下假设：SCN中的VIP神经元需要携带和维持昼夜运动节律，OB中的VIP神经元需要OB中的节律和嗅觉行为。这一目的还测试了VIP神经元中的时钟基因是否对它们的节律性和行为的这些节律是必不可少的。目的3利用相关的放电和基因表达模式以及药理学来定位功能连接以及谷氨酸、一氧化氮和血管活性肠肽在脊髓核内昼夜节律同步性中的相对作用。最近在许多哺乳动物组织中发现的可能的昼夜节律振荡器导致了一种假说，即昼夜节律系统是分级组织的，这种协调的破坏可能是包括抑郁症在内的各种神经疾病的基础。这些实验将首次确定协调大脑中整体日常节奏的机制，以及它们在行为中扮演的不同角色。行为和情绪的日常节奏是由大脑中的生物钟驱动的。这个项目考察了特定神经元和信号分子在大脑区域内和脑区之间的神经活动和基因表达的昼夜调节中的作用，以及在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.