Regulation of Hypothalamic Sleep-wake Neuronal System

描述(由申请人提供)：有证据表明，下丘脑肌酸(Hcrt)，也称为食欲素，可以促进行为唤醒，抑制快速眼动(REM)睡眠。HCRT系统的缺失或功能障碍与嗜睡症的症状有关，包括嗜睡。在大脑中，Hcrt神经元定位于穹隆周围-外侧下丘脑区(PF-LHA)。大多数PF-LHA神经元在行为觉醒时表现活跃，在安静觉醒(QW)和非快速眼动睡眠时表现出较低的活动。相比之下，视前区腹外侧区(VLPO)和正中视前核(MnPN)中的大多数神经元在睡眠时都是活跃的。MnPN内的睡眠活动神经元多为GABA能神经元。MnPN GABA能神经元是Pf-LHA的传入来源。调节PF-LHA唤醒系统状态依赖活动的神经递质/神经调节剂的身份尚不清楚。Hcrts在调节MnPN和VLPO中睡眠活动神经元的状态依赖性活动中的作用尚不清楚。首先，我们假设，腺苷能抑制增加有助于在QW期间抑制PF-LHA神经元的活动，而在非REM睡眠期间，它们的进一步抑制是由于伽马氨基丁酸(GABA)介导的抑制增加所致。我们将量化通过相邻微透析探针传递的腺苷和GABA激动剂和拮抗剂对自由行为大鼠PF-LHA神经元状态依赖的细胞外活动的影响。第二，我们假设MnPN促进睡眠的部分机制是通过抑制PF-LHA中的觉醒促进系统，并且这种抑制是通过GABA能机制介导的。我们将研究在存在和不存在GABA受体拮抗剂的情况下，电和化学刺激对PF-LHA神经元状态依赖活动的影响。通过hcrt-1肽和c-Fos蛋白的双标记免疫组织化学染色，进一步研究GABA能和腺苷能药物以及刺激MnPN对Hcrt神经元的影响。我们发现，视前区微量注射hcrt-1可以促进觉醒。第三，我们假设Hcrt系统部分通过抑制MnPN和VLPO中的睡眠活动神经元来促进觉醒。我们将确定HCRT局部微透析灌流抑制VLPO和MnPN中睡眠活动神经元的能力。拟议的研究将极大地促进我们对包括Hcrt神经元在内的PF-LHA觉醒系统的状态相关控制的神经递质基础的理解，以及它们与视前睡眠促进系统的相互作用。这将有助于寻找更有针对性和更具体的睡眠障碍治疗策略。

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.