Pontine circuitry regulating REM sleep and atonia

描述（由申请人提供）：快速眼动（REM）睡眠是一种以皮层和海马脑电图激活、快速眼动和肌肉张力失调为特征的行为状态。虽然近年来在以下方面取得了一些进展：1)快速眼动睡眠的脑桥开关回路的位置；2)调节快速眼动现象的神经递质，即肌肉弛缓、皮层和海马脑电图的激活；3)该回路的功能障碍如何形成快速眼动睡眠行为障碍的神经病理学基础，但我们的知识仍然存在主要空白。我们实验室最近的工作揭示了在中孔板被盖中存在相互抑制的快速眼动关闭和快速眼动打开区域，这可能构成了快速眼动睡眠切换电路的神经解剖学基础。这些发现构成了目前研究计划的基础，假设了一个类似于电子触发器开关的快速眼动开关电路模型。在这种触发器式的安排下，gaba能快速眼动神经元（位于外侧背侧被盖核下（SLD））抑制gaba能快速眼动神经元（位于腹外侧导水管周围灰质（vlPAG）和外侧桥脑被（LPT）），反之亦然。在这个脑桥“开关”中，快速眼动区包含两个谷氨酸能神经元群，其中第一个投射到基底前脑，调节快速眼动睡眠时的脑电图成分，第二个投射到腹内侧髓质和脊髓，调节快速眼动睡眠时的肌张力。为了证明谷氨酸能SLD神经元在产生非张力性快速眼动中的关键作用，我们将通过立体定向将含有Cre重组酶基因的腺相关病毒（AAV-Cre）注射到具有水泡性谷氨酸转运蛋白2 （VGLUT2）基因lox-P修饰等位基因的条件敲除小鼠的SLD中，选择性地消除SLD中的谷氨酸能神经传递。我们将同样通过立体定向将AAV-Cre注射到具有囊状GABA转运体（VGAT）的lox-P修饰等位基因的小鼠中，消除SLD和LPT中的GABA能神经传递。最后，我们将通过对大鼠注射食欲素皂苷和对VGAT和VGLUT2小鼠注射AAV-Cre来研究腹内侧髓质在REM弛缓中的作用。本研究的发现将为理解包括REM睡眠行为障碍在内的各种睡眠障碍的病理生理机制和病因基础提供一个背景。公共卫生相关性：快速眼动睡眠行为障碍（RBD）是一种睡眠异常，其特征是在快速眼动睡眠期间缺乏运动张力；然而，RBD的病理生理基础尚不清楚。本研究的目的是描述脑桥嗅觉下核在RBD病理生理中的作用。我们的研究结果将为RBD的诊断和治疗策略的发展提供基础。

Description (provided by applicant): Rapid eye movement (REM) sleep is a behavioral state characterized by activation of the cortical and hippocampal EEG, rapid eye movements and muscle atonia. While some progress has been made in recent years in the effort to delineate 1) the locus of the pontine switching circuitry for REM sleep, 2) the neurotransmitters regulating REM phenomenon, i.e., muscle atonia, activation of the cortical and hippocampal EEG, and 3) how dysfunction of this circuitry may form the neuropathologic basis of REM sleep behavior disorder, major gaps remain in our knowledge. Recent work by our laboratory has revealed the presence of mutually inhibitory REM-off and REM-on areas in the mesopontine tegmentum that may form the neuroanatomical basis of the switching circuitry for REM sleep. These findings, which form the basis of the present research plan, posit a REM switching circuitry model that is analogous to an electronic 'flip-flop' switch. In this flip-flop switch arrangement, GABAergic REM-on neurons (located in the sublateraldorsal tegmental nucleus (SLD)) inhibit GABAergic REM-off neurons (located in the ventrolateral periaqueductal gray matter (vlPAG) and lateral pontine tegmentum (LPT)) and vice versa. Inside this pontine brainstem "switch" the REM-on area contains two populations of glutamatergic neurons, the first of which projects to the basal forebrain and regulates EEG components of REM sleep and the second which projects to the ventromedial medulla and spinal cord and regulates atonia during REM sleep. To demonstrate the critical role of glutamatergic SLD neurons in producing REM without atonia, we will selectively eliminate glutamatergic neurotransmission in the SLD by stereotaxically injecting an adeno-associated virus containing the gene for Cre recombinase (AAV-Cre) into the SLD of conditional knock-out mice with lox-P modified alleles of the vesicular glutamate transporter 2 (VGLUT2) genes. We will similarly eliminate GABAergic neurotransmission in the SLD and LPT by stereotaxically injecting AAV-Cre into mice with lox-P modified alleles of the vesicular GABA transporter (VGAT). Finally, we will examine the role of the ventromedial medulla in REM atonia by combining injections of orexin-saporin into rats and AAV-Cre injections into VGAT and VGLUT2 mice. Findings from the present proposal will provide a context for understanding the pathophysiologic mechanisms and etiological bases for a variety of sleep disorders, including REM sleep behavior disorder. PUBLIC HEALTH RELEVANCE: REM sleep behavior disorder (RBD) is a parasomnia characterized by the absence of motor atonia during REM sleep; however, the pathophysiologic basis of RBD remains unresolved. The objective of the present proposal is to delineate the role of the pontine sublaterodorsal nucleus in the pathophysiology of RBD. Results from our studies will provide the foundation for the development of diagnostic and therapeutic strategies for treating RBD.