Regulation of arousal state by the suprachiasmatic clock

项目摘要 在理解昼夜节律所依据的电路、细胞和突触基础方面存在着根本性的差距 起搏器位于哺乳动物的下丘脑视交叉上核(SCN)，调节大脑的觉醒。 这种知识差距是一个重要的问题，因为它不仅降低了我们治疗唤醒障碍的能力， 如嗜睡和疲劳，也影响治疗和加深许多认识 神经精神疾病、神经退行性疾病和神经疾病，通常包括严重的唤醒障碍， 包括抑郁症和阿尔茨海默氏症。我们的长期目标是了解解剖学、细胞学和 SCN调节大脑觉醒的突触流出基础。本申请的目标是1) 确定产生S神经元是否促进觉醒，2)确定它们的状态依赖性 3)建立横跨下丘脑背内侧核的功能性三突触回路 (DMH)-&GT；腹外侧视前核(VLPO)，4)定义DMH-&GT；VLPO的功能性突触生理学 接口，包括目标神经元的细胞轮廓，5)确定到SCNNMS的突触前输入 6)定义了SCNNMS神经元的分子/转录图景。中心假设是 SCNNMS神经元对觉醒水平的时钟调节既是必要的，也是充分的。其基本原理是 建议的研究是确定SCN可以通过的解剖、细胞和突触基础 调节唤醒水平是控制它们和减少功能障碍的关键第一步 有觉醒障碍的个体所经历的。在强劲的初步数据的指引下，这一假设将是 通过追求四个特定目标进行测试：1)在体内确定SCNNMS神经元的急性激活/抑制是否可以 分别促进/减弱觉醒，并通过体内钙离子成像，如果他们表现出觉醒活跃的轮廓；2) 证明SCNNMS神经元在功能上与促进睡眠的VLPO有突触联系 3)确定SCNNMS神经元突触前输入的来源，并确认 功能连接性；以及4)确定SCNNMS细胞群体内的分子异质性。这个 方法在智力和技术上都是创新的，因为它试图揭示 SCN调节大脑唤醒，因为它使用了新开发的和 经过验证的方法。这项拟议的研究意义重大，因为预计它将垂直推进和 扩大对服务于SCN时钟的细胞和突触机制的理解。最终，这样的 知识有可能为减少功能障碍和负面影响的治疗方法的发展提供信息 不仅越来越多的以昼夜节律和觉醒为基础的患者经历了健康影响 紊乱，如睡过头和疲劳，也是那些患有神经精神疾病的人之一， 有严重觉醒障碍的神经退行性和神经性疾病，如抑郁症或 阿尔茨海默氏症，包括许多与时钟有关或被证明有贡献的疾病。

Project Summary There is a fundamental gap in understanding the circuit, cellular and synaptic bases by which the circadian pacemaker, located in the hypothalamic suprachiasmatic nucleus (SCN) of mammals, regulates brain arousal. This knowledge gap is an important problem because it not only reduces our ability to treat arousal disorders, such as hypersomnia and fatigue, but also impacts treatment and deeper understanding of many neuropsychiatric, neurodegenerative and neurological disorders that often include severe arousal disruption, including depression and Alzheimer's disease. Our long-term goal is to understand the anatomic, cellular and synaptic outflow bases by which the SCN regulates brain arousal. The objectives of this application are to 1) determine if Neuromedin S-producing SCN (SCNNMS) neurons promote arousal, 2) define their state-dependent firing profile in vivo; 3) establish a functional tri-synaptic circuit spanning SCNNMS->dorsomedial hypothalamus (DMH)->ventrolateral preoptic nucleus (VLPO), 4) define the functional synaptic physiology of the DMH->VLPO interface, including the cellular profile of the targeted neurons, 5) determine presynaptic inputs to SCNNMS neurons, and 6) define the molecular/transcriptional landscape of SCNNMS neurons. The central hypothesis is that SCNNMS neuron are both necessary and sufficient for clock regulation of arousal levels. The rationale for the proposed research is that identifying the anatomic, cellular and synaptic bases by which the SCN can modulate arousal levels is a critical first step towards manipulating them and reducing the dysfunction experienced by individuals with disorders of arousal. Guided by strong preliminary data, this hypothesis will be tested by pursuing four specific aims: 1) Determine in vivo if acute activation/inhibition of SCNNMS neurons can promote/attenuate arousal, respectively, and, via in vivo Ca+2 imaging, if they exhibit a wake-active profile; 2) Demonstrate that SCNNMS neurons are functionally, synaptically connected with sleep-promoting VLPO neurons via a DMH `relay'; 3) Determine the sources of presynaptic inputs to SCNNMS neurons and confirm functional connectivity; and 4) Determine molecular heterogeneity within the SCNNMS cell population. The approach is intellectually and technically innovative because it seeks to reveal the mechanistic basis by which the SCN regulates brain arousal and because it employs a novel combination of newly developed and validated approaches. The proposed research is significant, because it is expected to vertically advance and expand understanding of the cellular and synaptic mechanisms subserving the SCN clock. Ultimately, such knowledge has the potential to inform the development of treatments to reduce the dysfunction and negative health effects experienced by not only the growing number of patients with circadian- and arousal-based disorders, such as hypersomnia and fatigue, but also of those suffering one of the host of neuropsychiatric, neurodegenerative and neurological disorders with severe arousal disruption, such as depression or Alzheimer's disease, including many in which a clock contribution has been implicated or demonstrated.