Pontine circuitry regulating REM sleep and atonia

描述(申请人提供)：快速眼动(REM)睡眠是一种行为状态，特征是大脑皮层和海马区脑电激活，快速眼球运动和肌肉张力。尽管近年来在描述1)REM睡眠的桥脑转换回路的位置，2)调节REM现象的神经递质，即肌肉张力，皮质和海马区EEG的激活，以及3)该回路的功能障碍如何形成REM睡眠行为障碍的神经病理基础方面取得了一些进展，但我们的认识仍然存在重大差距。我们实验室最近的工作揭示了桥中被盖存在相互抑制的REM-Off和REM-On区域，这可能构成了REM睡眠开关电路的神经解剖学基础。这些发现构成了本研究计划的基础，提出了一种类似于电子触发器开关的REM开关电路模型。在这种触发开关排列中，GABA能REM-ON神经元(位于被盖背外侧亚核(SLD))抑制GABA能REM-ON神经元(位于中脑导水管周围灰质腹外侧部(VlPAG)和桥被盖外侧(LPT))，反之亦然。在这个脑桥脑干“开关”内，REM-On区包含两组谷氨酸能神经元，第一组投射到基底前脑，调节REM睡眠的脑电成分，第二组投射到腹内侧髓和脊髓，调节REM睡眠中的张力。为了证明谷氨酸能SLD神经元在产生无张力的REM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)注射到条件基因敲除小鼠的SLD中，使囊泡谷氨酸转运体2(VGLUT2)基因的lox-P修饰等位基因进入SLD，从而选择性地消除SLD中的谷氨酸能神经传递。我们将通过立体定向地将AAV-CRE注射到具有囊泡GABA转运体(VGAT)LOX-P修饰等位基因的小鼠中，类似地消除SLD和LPT中的GABA能神经传递。最后，我们将通过联合向大鼠注射增食欲素-皂苷和向VGAT和VGLUT2小鼠注射AAV-CRE来研究延髓腹内侧部在REM张力中的作用。本提案的发现将为理解各种睡眠障碍的病理生理机制和病因学基础提供背景，包括快速眼动睡眠行为障碍。

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.