The Tuberal Hypothalamus and Arousal State Control

下丘脑结节和觉醒状态控制

• 批准号: 9751986
• 负责人: Thomas S Kilduff
• 金额: $ 65.93万
• 依托单位: SRI INTERNATIONAL
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-30 至 2021-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9751986
• 关键词: Ablation; Affect; Amygdaloid structure; Anatomy; Animal Model; Animals; Area; Arousal; Brain; Brain region; Cataplexy; Cell Nucleus; Cells; Chronic; Complement; Diet; Dorsal; Doxycycline; Eating; Electrophysiology (science); Energy Metabolism; Excision; Fluorescence; Food Energy; Functional Imaging; Head; Human; Hypothalamic structure; Image; Investigation; Knockout Mice; Ligands; Measures; Medial; Metabolism; Modeling; Mus; Narcolepsy; Neurodegenerative Disorders; Neurons; Peptides; Pharmacogenetics; Phenotype; Physiological; Population; REM Sleep; Rabies; Reporting; Role; Sleep; Sleep Disorders; Sleep Wake Cycle; Sleeplessness; System; Testing; Wakefulness; base; cell type; cholinergic neuron; clinically relevant; experimental study; follow-up; hypocretin; imaging study; locus ceruleus structure; mammilloinfundibular nucleus structure; melanin-concentrating hormone; melanin-concentrating hormone receptor; mouse model; nerve supply; optogenetics; patch clamp; restoration; sleep regulation

Melanin-concentrating hormone (MCH) and hypocretin/orexin (HCRT)-expressing neurons are intermingled populations in the tuberal hypothalamus that project widely throughout the brain to many of the same terminal fields. Whereas the HCRT system has been implicated in the control of wakefulness because the sleep disorder narcolepsy results when these cells degenerate, this system is also involved in energy metabolism. Conversely, the MCH system has primarily been associated with food intake and energy metabolism, but recent studies have established that MCH neurons also participate in the regulation of sleep and wakefulness. The hypothesis underlying this proposal is that the HCRT system is wake-stabilizing and REM-inhibiting whereas the MCH system is sleep-facilitating and REM-stabilizing. We will test this hypothesis by determining the phenotype of mice in which either the HCRT or MCH neurons have been partially ablated by removal of doxycycline in the diet of two conditional mouse models. We will then evaluate whether partial ablation of the HCRT neurons results in a phenotype of narcolepsy without cataplexy and whether cataplexy is exacerbated by simultaneously eliminating both neuronal populations. We will also assess whether direct connectivity exists between these cell groups using optogenetically-assisted neuroanatomical tracing and whole-cell patch- clamp electrophysiology in the presence and absence of selective HCRT and MCH receptor antagonists. To assess what occurs in the brain when the HCRT neurons degenerate as in human narcolepsy, we will use the conditional HCRT neuron ablation model to determine how the excitability of the MCH population is affected by chronic loss of HCRT input. We will also use conditional MCH neuron ablation to assess the converse effect of MCH loss on HCRT neuron excitability. Based on recordings from a limited number of cells in head-fixed animals, the HCRT and MCH neurons have been reported to have reciprocal activity across the sleep-wake cycle with HCRT neurons having their highest firing rates during active wakefulness and MCH neurons being primarily active during REM sleep. To determine the accuracy of this conclusion, we will use genetically- encoded Ca2+ indicators and microendoscopic imaging to measure the activity of hundreds of HCRT and MCH neurons across the sleep/wake cycle in unrestrained, freely-moving animals. To evaluate whether the HCRT and MCH neurons are functionally interconnected, we will pharmacogenetically activate one population while imaging Ca2+ fluorescence in the other population in the presence of selective HCRT and MCH receptor antagonists. Lastly, since these two populations project to many of the same brain regions, we will assess their relative input to brain areas known to be involved in arousal state control, specifically, the locus coeruleus, tuberomammillary nucleus, medial septum, and the amygdala. Together, these experiments should provide a more complete picture of the anatomical and functional connectivity of these two populations and the consequences of selective loss of one population or the other.

黑色素浓缩激素 (MCH) 和下丘脑分泌素/食欲素 (HCRT) 表达神经元混合在一起 下丘脑结节中的群体广泛投射到整个大脑的许多相同的终端 字段。鉴于 HCRT 系统与觉醒控制有关，因为睡眠 当这些细胞退化时就会导致发作性睡病，这个系统也参与能量代谢。 相反，MCH 系统主要与食物摄入和能量代谢有关，但是 最近的研究表明，MCH 神经元也参与睡眠和觉醒的调节。 该提议的假设是 HCRT 系统具有唤醒稳定作用和 REM 抑制作用 而 MCH 系统则促进睡眠并稳定 REM。我们将通过确定来检验这个假设 小鼠的表型，其中 HCRT 或 MCH 神经元已通过去除 两种条件小鼠模型饮食中的多西环素。然后我们将评估是否部分消融 HCRT 神经元导致发作性睡病的表型，但不伴有猝倒以及猝倒是否加剧 通过同时消除两个神经元群。我们还将评估是否直接连接 使用光遗传学辅助神经解剖追踪和全细胞贴片在这些细胞群之间存在 在存在和不存在选择性 HCRT 和 MCH 受体拮抗剂的情况下钳位电生理学。到 为了评估当 HCRT 神经元像人类发作性睡病一样退化时大脑中会发生什么，我们将使用 条件 HCRT 神经元消融模型，用于确定 MCH 群体的兴奋性如何受到影响 HCRT 输入的慢性损失。我们还将使用条件 MCH 神经元消融来评估相反的效果 HCRT 神经元兴奋性的 MCH 损失。基于头部固定的有限数量的细胞的记录 据报道，在动物中，HCRT 和 MCH 神经元在睡眠-觉醒过程中具有相互的活动 HCRT 神经元在主动觉醒期间具有最高的放电率，而 MCH 神经元则处于循环状态 主要在快速眼动睡眠期间活跃。为了确定这个结论的准确性，我们将使用遗传学- 编码的 Ca2+ 指标和显微内窥镜成像可测量数百个 HCRT 和 MCH 的活性 不受约束、自由活动的动物的睡眠/觉醒周期中的神经元。评估 HCRT 是否 和 MCH 神经元在功能上是相互关联的，我们将通过药物遗传学激活一个群体，同时 在选择性 HCRT 和 MCH 受体存在的情况下，对其他群体中的 Ca2+ 荧光进行成像 对手。最后，由于这两个群体投射到许多相同的大脑区域，我们将评估 它们对已知参与唤醒状态控制的大脑区域的相对输入，特别是蓝斑， 结节乳头核、内侧隔膜和杏仁核。总之，这些实验应该提供一个 更完整地了解这两个群体的解剖学和功能连接以及 一种种群或另一种种群选择性丧失的后果。