Neurobiological studies of gammahydroxybutyrate

描述（由申请人提供）：Gammahydroxybutyrate （GHB）是一种中间代谢产物，对中枢神经系统（CNS）的活性有深远的影响，特别是对意识。由于其催眠作用，GHB既成为一种滥用药物，又自相矛盾地成为治疗睡眠紊乱性嗜睡症的临床有效疗法。嗜睡症是一种与快速眼动（REM）睡眠相关的疾病，大约每1000个美国人中就有1人患有此病，其特征是白天过度嗜睡（EDS）、猝厥（由情绪刺激引起的肌肉张力突然丧失）以及一系列其他症状。Xyrem， GHB的钠盐，已经被美国食品和药物管理局批准用于治疗发作性睡病的猝厥和EDS症状。GHB促进脑电图中的慢波活动（SWA）和慢波睡眠（SWS），从而巩固夜间睡眠并导致第二天的警觉性增加。尽管具有临床应用价值，但GHB的作用机制仍存在争议，有证据表明GHB通过GABA-B受体和中枢神经系统中特定的GHB结合位点起作用。本项目的具体目标是确定GHB诱导的SWA的神经基质，并了解GHB对发作性睡病/猝倒的治疗作用机制。为了实现这些目标，我们将开发一种小鼠发作性睡病/猝倒模型，其中下丘脑分泌素（Hcrt）神经元在出生后退化，就像人类发作性睡病一样。我们将使用这些hcrt/ataxin-3小鼠来跟进我们的初步结果，这些结果表明GHB可以像在人类中一样减轻类似中风的症状，并验证这些治疗效果是通过GABA-B受体介导的假设。我们将进行功能神经解剖学研究，以验证GHB对hcrt/ataxin-3小鼠行为状态调节区域的差异影响。基于GHB诱导蓝斑（LC） Fos表达的初步结果，我们将使用神经毒素sp -4损伤去甲肾上腺素能细胞，以验证完整的LC是GHB治疗效果所必需的假设。我们还将进行细胞电生理研究，以确定LC或腹外侧视前区（VLPO）神经元的内在特性是否受到急性或慢性暴露于GHB的影响。最后，我们将评估GHB的治疗效果是否与大脑基因表达变化有关。上述研究结果将增强我们对GHB治疗活性背后的神经生物学的理解，也可能为中风和EEG SWA背后的细胞和分子机制提供见解。发作性睡症是一种以白天过度嗜睡和相关症状为特征的睡眠障碍，研究人员观察到大脑中下丘脑分泌素（Hcrt）神经元的退化。γ -羟基丁酸酯（GHB）是一种治疗睡眠障碍性发作性睡病的有效药物，但其作用机制尚不清楚。我们将利用小鼠发作性睡病模型，其中Hcrt神经元在出生后退化，就像人类发作性睡病一样，以了解GHB如何对人类发作性睡病有益。

DESCRIPTION (provided by applicant): Gammahydroxybutyrate (GHB), a product of intermediary metabolism, has profound effects on the activity of the central nervous system (CNS), particularly on consciousness. Because of its soporific effects, GHB has become both a drug of abuse and, paradoxically, a clinically useful therapeutic for treatment of the sleep disorder narcolepsy. Narcolepsy, a Rapid Eye Movement (REM) sleep-related disorder that afflicts approximately 1 in 1000 Americans, is characterized by excessive daytime sleepiness (EDS), cataplexy (a sudden loss of muscle tone triggered by emotional stimulation), and a cluster of other symptoms. Xyrem, the sodium salt of GHB, has been approved by the U.S. Food and Drug Administration for the treatment of both the cataplexy and EDS symptoms of narcolepsy. GHB facilitates slow wave activity (SWA) in the EEG and slow wave sleep (SWS), thereby consolidating nocturnal sleep and resulting in increased alertness on the subsequent day. Despite its clinical utility, the mechanism of action of GHB remains controversial with evidence for action both through GABA-B receptors and through specific GHB binding sites in the CNS. The specific goals of this project are to identify the neural substrates of GHB-induced SWA and understand the mechanism(s) underlying the therapeutic effects of GHB on narcolepsy/cataplexy. To achieve these goals, we will exploit a mouse model of narcolepsy/cataplexy in which the hypocretin (Hcrt) neurons degenerate postnatally as they do in human narcoleptics. We will follow up on our preliminary results using these hcrt/ataxin-3 mice which indicate that GHB can reduce cataplexy-like symptoms as it does in humans and test the hypothesis that these therapeutic effects are mediated through the GABA-B receptor. We will conduct functional neuroanatomical studies to test the hypothesis that GHB differentially affects behavioral state regulatory regions in hcrt/ataxin-3 mice. Based on our preliminary results in which GHB induces Fos expression in the locus coeruleus (LC), we will use the neurotoxin DSP-4 to lesion noradrenergic cells to test the hypothesis that an intact LC is necessary for the therapeutic effect of GHB. We will also conduct cellular electrophysiological studies to determine whether the intrinsic properties of the neurons in the LC or the ventrolateral preoptic area (VLPO) are affected by acute or chronic exposure to GHB. Lastly, we will evaluate whether the therapeutic efficacy of GHB is associated with brain gene expression changes. The results of the studies proposed above will enhance our understanding of the neurobiology that underlies the therapeutic activity of GHB and may also provide insights into the cellular and molecular mechanisms that underlie cataplexy and EEG SWA. PUBLIC HEALTH RELEVANCE In patients with narcolepsy, a sleep disorder characterized by excessive daytime sleepiness and related symptoms, degeneration of hypocretin (Hcrt) neurons in the brain has been observed. Gammahydroxybutyrate (GHB) is a clinically useful therapeutic for treatment of the sleep disorder narcolepsy but the mechanism of action is unknown. We will exploit a mouse model of narcolepsy in which the Hcrt neurons degenerate postnatally as they do in human narcoleptics to understand how GHB is beneficial in human narcolepsy.