Identification Orexinergic Wake-Promoting Pathways

对于患有发作性睡病、阻塞性睡眠呼吸暂停和许多其他睡眠障碍的人来说，慢性嗜睡是导致功能障碍的最大原因。人们对嗜睡的神经生物学知之甚少，但嗜睡症是由增食欲素/下丘脑泌素缺乏引起的这一发现为研究调节行为状态的途径提供了一个独特的机会。我们假设，食欲素通过增加特定觉醒区域的活动，如蓝斑和结节乳头核，促进和稳定觉醒。我们实验的总体目标是定义生理和本质 食欲素信号受损的小鼠嗜睡的神经通路。 首先，我们将详细描述食欲素缺乏小鼠的嗜睡情况，以更好地了解食欲素缺乏所产生的行为变化。除了对睡眠/醒来行为的彻底分析外，我们还将评估这些小鼠保持警觉的能力，因为警觉性受损是嗜睡的一个敏感和重要的功能后果。 然后，我们将使用一种创新和强大的分子技术来识别大脑中食欲素促进和稳定觉醒的区域。具体地说，我们将产生可诱导的食欲素受体敲入小鼠，这些小鼠出生时既没有食欲素受体，也没有食欲素受体。我们将把含有Cre重组酶的腺相关病毒载体微量注射到这些小鼠的特定脑区，以诱导增食欲素受体的在位、局部表达。然后，我们将检查这些小鼠的睡眠/觉醒行为和警觉性，以确定哪些大脑区域足以发挥增食欲素的促醒作用。 最后，我们将通过将这些可诱导的食欲素受体敲入小鼠与仅在组胺、儿茶酚胺或胆碱能神经元中表达Cre的转基因小鼠杂交，确定食欲素促进和稳定觉醒的神经化学特定群体。我们预测，增食欲素受体在结节乳头核或其他唤醒区域的表达将使这些小鼠保持清醒的能力正常化。 这些实验将确定哪些神经化学特定的神经元群体足以维持由增食欲素介导的正常觉醒和警觉，从而为发作性睡病和其他睡眠障碍的嗜睡原因提供关键的见解。

Chronic sleepiness is the greatest cause of functional impairment for people with narcolepsy, obstructive sleep apnea, and many other sleep disorders. Very little is known about the neurobiology of sleepiness, but the discovery that narcolepsy is due to orexin/hypocretin deficiency provides a unique opportunity to investigate the pathways that regulate behavioral state. We hypothesize that orexin promotes and stabilizes wakefulness by increasing the activity of specific arousal regions such as the locus coeruleus and tuberomammillary nucleus. The overall goal of our experiments is to define the physiology and essential neural pathways that underlie the sleepiness of mice with impaired orexin signaling. First, we will characterize in detail the sleepiness of orexin deficient mice to gain a better understanding of the behavioral changes produced by orexin deficiency. In addition to a thorough analysis of sleep/wake behavior, we will assess the ability of these mice to maintain vigilance as impaired vigilance is a sensitive and functionally important consequence of sleepiness. We will then use an innovative and powerful molecular technique to identify the brain regions through which orexin promotes and stabilizes wakefulness. Specifically, we will produce inducible orexin receptor knock-in mice that are born lacking both orexin receptors. We will microinject an adeno-associated viral vector containing Cre recombinase into specific brain regions of these mice to induce eutopic, focal expression of the orexin receptors. We then will examine the sleep/wake behavior and vigilance of these mice to determine which brain regions are sufficient for orexin's wake-promoting effects. Lastly, we will define the neurochemically specific populations through which orexin promotes and stabilizes wakefulness by crossing these inducible orexin receptor knock-in mice with transgenic mice expressing Cre only in the histaminergic, catecholaminergic, or cholinergic neurons. We predict that expression of orexin receptors in the tuberomammillary nucleus or other arousal regions will normalize the ability of these mice to maintain wakefulness. These experiments will define which neurochemically specific populations of neurons are sufficient for the normal maintenance of wakefulness and vigilance mediated by orexin, thus providing crucial insights into the cause of sleepiness in narcolepsy and other sleep disorders.