Median Preoptic Nucleus and the Control of Sleep

下丘脑视前区（POA）在睡眠控制中的作用得到了损伤、刺激和神经元记录实验结果的支持。 POA内假定的睡眠调节细胞群的精确位置尚不完全清楚，但最近通过应用c-fos蛋白免疫反应（IR）方法取得了进展。 在大鼠腹外侧POA（vlPOA）中发现了一组局部神经元，它们在睡眠过程中表现出Fos免疫反应。 vlPOA神经元已显示投射到后下丘脑和脑干中的单胺能唤醒系统，并含有抑制性神经递质γ-氨基丁酸（GABA）。 神经元记录研究证实了vlPOA内存在具有睡眠相关放电模式的神经元。所提出的工作的目标是表征第二POA区域的解剖学和生理学特征，其中已经定位了表现出渗漏相关Fos-IR的神经元，即正中视前核（MnPN）。 提出的实验将回答以下问题：1）MnPN是否含有高浓度的具有睡眠相关放电模式的神经元，如先前在vlPOA中发现的那样？2)表现出睡眠相关Fos-IR的MnPN神经元也是GABA能的吗？3)表现出睡眠相关Fos IR的MnPN神经元是否投射到基底前脑大细胞、外侧下丘脑穹窿周围区、中缝背核和脑桥背外侧的唤醒系统？4)具有睡眠相关放电的MnPN神经元的子集是否也是热敏的，如先前对于vlPOA神经元所示的那样？5)参与体液稳态控制的MnPN神经元是与睡眠相关的MnPN神经元不同的群体吗？拟议的工作将深入研究一个重要的POA神经元组，MnPN的解剖，神经化学和电生理特征。 计划中的实验将有助于更全面地了解下丘脑机制在正常和紊乱的睡眠和觉醒状态中的作用。

A role for the preoptic area (POA) of the hypothalamus in the control of sleep is supported by the results of lesion, stimulation and neuronal recording experiments. The precise location of putative sleep-regulatory cell groups within the POA is incompletely understood, but recent progress has been made through application of the c-fos protein immunoreactivity (IR) method. A localized group of neurons in the ventrolateral POA (vlPOA) that exhibit Fos-IR during sleep has been described in rat. vlPOA neurons have been shown to project to monoaminergic arousal systems in the posterior hypothalamus and brainstem and to contain the inhibitory neurotransmitter gamma-aminobutyric acid (GABA). Neuronal recording studies confirmed the presence of neurons with sleep-related discharge patterns within the vlPOA. The goal of proposed work is to characterize the anatomy and physiology of a second POA region where neurons exhibiting seep- related Fos-IR have been localized, the median preoptic nucleus (MnPN). Proposed experiments will answer the following questions: 1) Does the MnPN contain a high concentration of neurons with sleep-related discharge patterns, like that previously found in the vlPOA? 2) Are MnPN neurons that exhibit sleep-related Fos-IR also GABAergic? 3) Do MnPN neurons that exhibit sleep-related Fos-IR project to arousal systems in the magnocellular basal forebrain, the perifornical region of the lateral hypothalamus, the dorsal raphe nucleus and the dorsolateral pons? 4) Are a subset of MnPN neurons with sleep- related discharge also thermosensitive, as has been previously shown for vlPOA neurons? 5) Are MnPN neurons that are involved in the control of body fluid homeostasis a separate population from sleep-related MnPN neurons? Proposed work will examine in depth the anatomical, neurochemical, and electrophysiological features of an important POA neuronal group, the MnPN. Planned experiments will contribute to a more complete understanding of the role of hypothalamic mechanisms in normal and disordered sleep and arousal states.