Regulation of Hypothalamic Sleep-wake Neuronal System

描述（由申请人提供）：证据表明下丘脑分泌素（Hcrt），也称为食欲素，促进行为唤醒和抑制快速眼动（REM）睡眠。Hcrt系统的丧失或功能障碍与嗜睡症的症状有关，包括过度嗜睡。在大脑中，Hcrt神经元位于下丘脑皮层外侧区（PF-LHA）。大多数PF-LHA神经元在行为唤醒时活跃，在安静清醒（QW）和非rem睡眠时表现出较低的活动。相反，视前区的腹外侧视前区（VLPO）和视前区的正中核（MnPN）的大多数神经元在睡眠期间是活跃的。MnPN中大多数睡眠活跃神经元是gaba能神经元。MnPN gaba能神经元是PF-LHA的传入源。调节状态依赖性活动PF-LHA唤醒系统的神经递质/神经调节剂的身份尚不清楚。Hcrts在调节MnPN和VLPO中睡眠活跃神经元的状态依赖性活动中的作用尚未确定。首先，我们假设腺苷能抑制的增加有助于QW期间PF-LHA神经元活性的抑制，而非快速眼动睡眠期间PF-LHA神经元活性的进一步抑制是由γ -氨基丁酸（GABA）介导的抑制增加引起的。我们将量化通过相邻微透析探针递送的腺苷和GABA激动剂和拮抗剂对自由行为大鼠PF-LHA神经元状态依赖性细胞外活性的影响。其次，我们假设MnPN通过抑制PF-LHA中的唤醒促进系统来促进睡眠，并且这种抑制是通过gaba能机制介导的。我们将研究在GABA受体拮抗剂存在和不存在的情况下，MnPN电刺激和化学刺激对PF-LHA神经元状态依赖性活性的影响。gaba能和腺苷能药物以及MnPN刺激对Hcrt神经元的影响将通过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hcrt-1显微注射到视前区促进觉醒。第三，我们假设Hcrt系统部分通过抑制MnPN和VLPO中的睡眠活跃神经元来促进觉醒。我们将确定Hcrts局部微透析灌注抑制VLPO和MnPN中睡眠活跃神经元活动的能力。所提出的研究将大大促进我们对包括Hcrt神经元在内的PF-LHA唤醒系统的状态相关控制的神经递质基础及其与视前睡眠促进系统的相互作用的理解。这将有助于寻找更有针对性和具体的治疗睡眠障碍的策略。

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.