Identification and manipulation of the neural ensembles mediating sundowning in an Alzheimer's disease mouse model

项目摘要/摘要 从原生动物到人类，生物体中到处都有昼夜节律。每一个细胞、器官和 生物系统以内生的24小时节律工作。然而，在阿尔茨海默病患者中 (AD)，一种影响记忆的神经退行性疾病，这种节律被抑制。除了认知之外 许多AD患者(约50%)在晚上或夜间也表现出烦躁不安和焦虑增加 几个小时，通常被称为日落。在这里，我们的目标是剖析睡眠背后的神经回路 紊乱，昼夜节律异常，以及表现为日落的焦虑样行为增加 以及它与认知衰退和阿尔茨海默病的关系。我们将利用行为 化验， 光遗传学， 全脑显微镜和活体钙成像。我们的初步证据表明阿尔茨海默病小鼠 与对照组(Ctrl)小鼠相比，焦虑样(例如，日落)行为增加 睡眠周期，但不是在觉醒周期之前。因此，在目标1A中，我们将使用PiezoSept小鼠 用于监测Ctrl和Ctrl的睡眠/清醒周期和昼夜回家运动活动的行为跟踪系统 为了更好地描述AD小鼠在清醒/睡眠周期中的特征，对不同年龄的AD小鼠进行了研究。我们会 还要测量他们在整个睡眠/清醒周期中不同时间点的焦虑行为。使用活动- 依赖标记小鼠，ArcCreERT2 x增强型黄色荧光蛋白(EYFP)小鼠与 APP/PS1(AD)模型，然后我们将识别全脑神经集成，从而识别神经网络 导致了AIM 1B的日落。这一小鼠品系允许对细胞进行不可磨灭的标记，表达 即刻早期基因(IEG)Arc/Arg3.1，并允许比较被激活的细胞 在一次体验中和在第二次体验中被激活的那些。在这里，我们将比较和 对比受试者在睡前类似焦虑的行为中活跃的神经集合 和唤醒周期。在Aim 2A中，在确定了哪些神经元在日落期间发生了变化后，我们 将使用Inscope ix的nVoke微型显微镜，在自由移动的AD x ArcCreERT2中成像钙瞬变 注射GCaMP6f病毒的小鼠，在黑暗与光明周期中。在这里，我们将能够增加 分辨率和我们可以将神经活动与增加的焦虑相关联的时间点(例如， 日落)行为。在目标2B中，我们将测试假设这些神经的光遗传调制 套装驱动/抑制日落行为。日落背后的神经回路还没有 被阐明，但这个项目将告诉我们受日落影响的新的大脑区域和神经电路 以及我们如何操纵这些系统来挽救AD的这种表型。

PROJECT SUMMARY / ABSTRACT Circadian rhythms are everywhere in living matter from protozoans to human beings. Every cell, organ, and biological system works on an endogenous 24-hour rhythm. However, in patients with Alzheimer's disease (AD), a neurodegenerative disorder affecting memory, this rhythm is dampened. In addition to cognitive decline, many AD patients (~50%) also exhibit agitation and increased anxiety in the evening or nocturnal hours, often referred to as sundowning. Here, we aim to dissect the neural circuitry underlying sleep disturbances, circadian rhythm abnormalities, and increased anxiety-like behavior representing sundowning and how it relates to cognitive decline and AD pathology. We will utilize behavioral assays, optogenetics, whole-brainmicroscopy, and in vivo Ca 2+ imaging. Our preliminary evidence suggests that AD mice exhibit increased anxiety-like (e.g., sundowning) behavior compared to control (Ctrl) mice immediately before their sleep cycle but not before their wake cycle. Therefore, in Aim 1A, we will use the PiezoSleep mouse behavioral tracking system to monitor sleep/wake cycles and circadian homecage locomotor activity in Ctrl and AD mice at different ages in order to better characterize AD mice throughout their wake/sleep cycle. We will also measure anxiety-like behavior at various points throughout their sleep/wake cycles. Using an activity- dependent tagging mouse, the ArcCreERT2 x enhanced yellow fluorescent protein (EYFP) mice crossed with the APP/PS1 (AD) model, we will then identify whole-brain neural ensembles and therefore, neural networks that contribute to sundowning in Aim 1B. This mouse line allows for the indelible labeling of cells expressing the immediate early gene (IEG) Arc/Arg3.1 and allows for a comparison between the cells that are activated during one experience and those that are activated during a second experience. Here, we will compare and contrast the neural ensembles within subjects that are active during anxiety-like behaviors prior to the sleep and wake cycles. In Aim 2A, after identifying which neuronal ensembles are altered during sundowning, we will use nVoke minimicroscopes from Inscopix, to image Ca2+ transients in freely moving AD x ArcCreERT2 mice, injected with a GCaMP6f virus, during the dark versus light cycle. Here, we will be able increase resolution and the time points at which we can correlate neural activity with increased anxiety-like (e.g., sundowning) behavior. In Aim 2B, we will then test the hypothesis that optogenetic modulation of these neural ensembles drives/inhibits sundowning behavior. The neural circuitry underlying sundowning has not yet been elucidated, but this project will inform us of novel brain regions and the neural circuitry affected by sundowning and how we can manipulate these systems to rescue this phenotype in AD.