Functional Connectivity of the Hypocretin/Orexin System

描述(申请人提供)：Hcrt系统是一种神经肽系统，参与行为唤醒、新陈代谢、成瘾、应激诱导镇痛(SIA)和神经内分泌功能。Hcrt缺乏会导致发作性睡病，这是一种中枢神经系统疾病，其特征是警觉性受损、嗜睡过度、社交活动受限和体重指数增加。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。 我们将结合光遗传学、在Hcrt神经元中特异表达光敏蛋白的转基因小鼠和条件转基因小鼠品系来进一步了解Hcrt系统。利用一种新的在Hcrt神经元中特异表达光敏质子泵ArchaerhoUV-3的转基因小鼠，我们将检验以下假设：(1)Hcrt神经元的光遗传失活会导致皮质活动、肌肉张力和指示睡眠的行为发生变化，以及(2)稳态睡眠压力调节Hcrt神经元的光遗传失活诱导睡眠的效果。利用5HT1a受体在Hcrt神经元有条件地过表达的转基因小鼠，我们将检验Hcrt神经元和5-羟色胺能中缝背核之间的负反馈环对睡眠和觉醒调节具有功能意义的假设。最后，我们将利用一种新创造的转基因小鼠，在其中白喉毒素A(DTA)的条件表达发生在Hcrt神经元中，以建立和验证一种新的人类发作性睡病小鼠模型，该模型更接近于人类的疾病。这项研究代表了一种综合的系统神经生物学方法来阐明神经递质系统的控制，该神经递质系统参与了一系列行为，其病理明显与中枢神经系统功能障碍有关，并可能导致治疗Hcrt缺乏的疾病(如发作性睡病)的新的药物治疗方法。

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.