Regulation of Hypothalamic Sleep-wake Neuronal System

描述（由申请人提供）：有证据表明，下丘脑泌素（Hcrt），也称为食欲素，促进行为觉醒并抑制快速眼动（REM）睡眠。Hcrt系统的缺失或功能障碍与包括过度嗜睡的发作性睡病症状相关。在大脑中，Hcrt神经元位于穹窿周围外侧下丘脑区（PF-LHA）内。大多数PF-LHA神经元在行为唤醒期间是活跃的，并且在安静清醒（QW）和非REM睡眠期间表现出较低的活动。相反，大多数神经元在腹外侧视前区（VLPO）和视前区的正中视前核（MnPN）在睡眠期间是活跃的。MnPN中的大多数睡眠活性神经元是GABA能神经元。MnPN GABA能神经元构成PF-LHA的传入来源。调节状态依赖性活动PF-LHA唤醒系统的神经递质/神经调质的身份是未知的。Hcrts在调节MnPN和VLPO中睡眠活性神经元的状态依赖性活动中的作用尚不明确。首先，我们假设增加的腺苷能抑制有助于抑制PF-LHA神经元的活动在QW，和他们的进一步抑制在非REM睡眠的结果增加γ-氨基丁酸（GABA）介导的抑制。我们将量化腺苷和GABA激动剂和拮抗剂通过相邻的微透析探针上的状态依赖性细胞外活动的PF-LHA神经元在自由行为的大鼠。其次，我们假设MnPN促进睡眠部分是通过抑制PF-LHA中的促醒系统，并且这种抑制是通过GABA能机制介导的。我们将研究的MnPN电和化学刺激的状态依赖性活动的PF-LHA神经元的GABA受体拮抗剂的存在和不存在的影响。GABA能和腺苷能药物以及MnPN刺激对Hcrt神经元的作用将通过hcrt-1肽和c-Fos蛋白的双标记免疫染色进一步研究。我们发现视前区微量注射hcrt-1可促进觉醒。第三，我们推测Hcrt系统通过抑制MnPN和VLPO中的睡眠活性神经元来促进唤醒。我们将确定局灶性微透析灌注Hcrts抑制VLPO和MnPN中睡眠活跃神经元活性的能力。拟议的研究将显着推进我们的理解PF-LHA唤醒系统，包括Hcrt神经元和它们的相互作用与视前睡眠促进系统的状态相关的控制的神经递质基础。这将有助于寻找更有针对性和具体的治疗策略，睡眠障碍。

DESCRIPTION (provided by applicant): Evidence suggests that hypocretins (Hcrt), also called orexins, promote behavioral arousal and suppress rapid eye movement (REM) sleep. Loss or dysfunction of Hcrt system is associated with symptoms of narcolepsy including excessive sleepiness. In the brain, Hcrt neurons are localized within the perifornical-lateral hypothalamic area (PF-LHA). A majority of PF-LHA neurons are active during behavioral arousal and exhibit lower activities during quiet waking (QW) and non-REM sleep. In contrast, a majority of neurons in the ventrolateral preoptic area (VLPO) and the median preoptic nucleus (MnPN) of the preoptic region are active during sleep. Most of the sleep-active neurons in MnPN are GABAergic. MnPN GABAergic neurons constitute a source of afferents to PF-LHA. The identity of neurotransmitters/neuromodulators that regulate the state-dependent activity PF-LHA arousal systems is unknown. The role of Hcrts in regulating the state-dependent activity of sleep-active neurons in MnPN and VLPO is uncharacterized. First, we hypothesize that increased adenosinergic inhibition contributes to the suppression of PF-LHA neuronal activity during QW, and their further suppression during non-REM sleep results from increased gamma-amino butyric acid (GABA)-mediated inhibition. We will quantify the effects of adenosine and GABA agonists and antagonists delivered through an adjacent microdialysis probe on the state-dependent extracellular activity of PF-LHA neurons in freely behaving rats. Second, we hypothesize that the MnPN promotes sleep in part by inhibiting the wake-promoting systems in PF-LHA and that this inhibition is mediated via a GABAergic mechanism. We will examine effects of the MnPN electrical and chemical stimulation on the state-dependent activity of PF-LHA neurons in the presence and the absence of GABA receptor antagonist. The effects of GABAergic and adenosinergic drugs as well as effects of MnPN stimulation on Hcrt neurons will be further studied by double label immunostaining for hcrt-1 peptide and for c-Fos protein. We found that hcrt-1 microinjection into preoptic area promotes arousal. Third, we hypothesize that Hcrt system promotes arousal in part by inhibiting sleep-active neurons in MnPN and VLPO. We will determine the ability of focal microdialysis perfusion of Hcrts to suppress the activity of sleep-active neurons in VLPO and MnPN. Proposed studies will significantly advance our understanding of the neurotransmitter basis of the state-related control of PF-LHA arousal systems including Hcrt neurons and their interactions with preoptic sleep-promoting systems. This will contribute to the search for more targeted and specific therapeutic strategies for sleep disorders.