Functional Connectivity of the Hypocretin/Orexin System

描述（申请人提供）：下丘脑分泌素/食欲素（Hcrt）系统是一种神经肽系统，参与行为唤醒、代谢、成瘾、应激诱导镇痛（SIA）和神经内分泌功能。Hcrt缺乏导致发作性睡病，一种以警觉性受损、过度嗜睡、社交活动受限和体重指数增加为特征的中枢神经系统疾病。鉴于该系统的功能意义，识别控制Hcrt系统和功能性Hcrt传出通路的输入具有临床意义。 我们将使用光遗传学，转基因小鼠，其中光敏蛋白在Hcrt神经元中特异性表达，和条件转基因小鼠品系的组合，以进一步了解Hcrt系统。使用在Hcrt神经元中特异性表达光敏质子泵古视紫红质-3的新型转基因小鼠，我们将测试以下假设：（1）Hcrt神经元的光遗传学失活将诱导皮质活动、肌张力和指示睡眠的行为的变化，以及（2）稳态睡眠压力调节Hcrt神经元的光遗传学失活诱导睡眠的功效。使用转基因小鼠，其中5 HT 1A受体有条件地过表达的Hcrt神经元，我们将测试的假设，Hcrt神经元和多巴胺能中缝背核之间的负反馈回路具有调节睡眠和觉醒的功能意义。最后，我们将利用一个新创建的转基因小鼠，其中白喉毒素A（DTA）的条件性表达发生专门在Hcrt神经元建立和验证一种新的小鼠模型的人类嗜睡症，更接近人类的疾病。这里提出的研究代表了一个综合的系统神经生物学的方法来阐明控制的神经递质系统牵连的一些行为，其病理学明显与中枢神经系统功能障碍，并可能导致新的药物治疗方法治疗的Hcrt功能不全，如嗜睡症。

DESCRIPTION (provided by applicant): The hypocretin/orexin (Hcrt) system is a neuropeptide system involved in behavioral arousal, metabolism, addiction, stress-induced analgesia (SIA) and neuroendocrine function. Hcrt deficiency results in narcolepsy, a CNS disorder characterized by impaired alertness, excessive sleepiness, restricted social activities, and increased body mass index. Given the functional significance of this system, identification of the inputs that control the Hcrt system and functional Hcrt efferent pathways is of clinical relevance. We will use a combination of optogenetics, transgenic mice in which light-sensitive proteins are expressed specifically in Hcrt neurons, and conditional transgenic mouse strains to further understand the Hcrt system. Using a novel transgenic mouse that expresses the light-sensitive proton pump Archaerhodopsin-3 specifically in Hcrt neurons, we will test the hypotheses that: (1) optogenetic inactivation of the Hcrt neurons will induce changes in cortical activity, muscle tone and behavior indicative of sleep, and (2), that homeostatic sleep pressure modulates the efficacy of optogenetic inactivation of Hcrt neurons to induce sleep. Using a transgenic mouse in which the 5HT1A receptor is conditionally overexpressed in Hcrt neurons, we will test the hypothesis that the negative feedback loop between Hcrt neurons and the serotonergic dorsal raphe nucleus has functional significance for the regulation of sleep and wakefulness. Lastly, we will exploit a newly created transgenic mouse in which conditional expression of diphtheria toxin A (DTA) occurs specifically in Hcrt neurons to establish and validate a novel mouse model of human narcolepsy that more closely resembles the human disorder. The research proposed here represents an integrated systems neurobiology approach to elucidate control of a neurotransmitter system implicated in a number of behaviors and whose pathology is clearly linked to CNS dysfunction and may lead to novel pharmacotherapeutic approaches for the treatment of disorders of Hcrt insufficiency such as narcolepsy.