Identifying deficits in brainstem respiratory circuits during viral encephalitis

 描述（由申请人提供）：总体目标是识别因虫媒病毒脑炎而受损的脑干内的呼吸神经回路，这些回路最终导致呼吸窘迫和衰竭。呼吸功能不全是虫媒病毒性脑炎的严重后果，可导致预后不良。啮齿动物模型已被用于确定神经缺陷引起呼吸窘迫，这是西尼罗河病毒（WNV）和其他病毒性脑炎死亡的主要病理生理机制。然而，被病毒损害的呼吸神经回路是未知的，这是本申请的主题。待检验的假设是，西尼罗河病毒损害了控制高碳酸血症反应的斜方肌后核/面旁呼吸组（RTN/pFRG）和控制呼吸节律产生的前Bötinger复合体（preBötC）。具体目标是：目标1。识别WNV感染新生小鼠髓核节律发生器（preBötC）中自发节律活动的缺陷。将从呼吸缺陷幼崽的preBötC切片中的颅神经XII小根获得抽吸电极测量值。 目标二。使用脑干-脊髓制备物（整体）识别呼吸回路缺陷 制备物）。将使用吸引电极同时测量XII和膈神经的神经根放电。将对髓质的腹侧表面进行钙成像，以确定RTN/pFRG的点化学感受器缺陷。目标3。目的1和2中鉴定的缺陷将在成年WNV感染小鼠中得到证实。通过测量XII和膈神经的神经放电，确定化学感受、节律发生和膈运动神经元的功能。将在单个小鼠内进行程序，以便我们可以更好地了解每种类型的缺陷对总WNV诱导的呼吸衰竭的贡献。在完成这些体内测量后，将对脑干和脊髓包含的呼吸功能区域进行组织学分析，以确定功能缺陷是否与解剖病理学相关。如果西尼罗河病毒感染对中枢呼吸功能产生不利影响，这将代表着一个范式的转变， 病毒性脑炎发病的神经机制。重要的是，该项目的成果 在即将到来的项目中，将为IRB应用提供支持数据，以测量WNV感染的人类受试者的呼吸功能

 DESCRIPTION (provided by applicant): The overall goal is to identify respiratory neuro-circuits within the brainstem damaged by arbovirus encephalitis that eventually lead to respiratory distress and failure. Respiratory insufficiency is a serious outcome of arbovirus encephalitis and can result in a poor prognosis. Rodent models have been used to establish that neurological deficits cause the respiratory distress, which is the primary patho- physiological mechanism of death for West Nile virus (WNV) and other viral encephalitis. However, the respiratory neuro-circuits damaged by the virus are unknown, which is subject of this application. The hypothesis to be tested is that WNV damages the retrotrapazoid nucleus/parafacial respiratory group (RTN/pFRG) controlling response to hypercapnia and the pre-Bötzinger complex (preBötC) controlling generation of breathing rhythm. The specific aims are: Aim 1. Identify deficits in spontaneous rhythmic activity in the medullary core rhythm generator (preBötC) from WNV-infected neonatal mice. Suction electrode measurements will be obtained from cranial nerve XII rootlets in the preBötC slice from pups with respiratory deficits. Aim 2. Identify deficits in respiratory circuitry using brainstem-spinal cord preparations (en bloc preparations) in neonatal WNV-infected mice. Nerve root discharges of the XII and phrenic nerves will be simultaneously measured using suction electrodes. The ventral surface of the medulla will be imaged for calcium to pin point chemoreceptor deficits to the RTN/pFRG. Aim 3. Deficits identified in Aims 1 and 2 will be corroborated in adult WNV-infected mice. Chemosensory, rhythmogenesis, and phrenic motor neurons functions will be ascertained by measuring nerve discharges in XII and phrenic nerves. Procedures will be performed within a single mouse so that we can better understand the contributions of each type of deficit to the total WNV-induced respiratory failure. Upon completion of these in vivo measurements, the brainstem and spinal cord containing regions of respiratory function will be analyzed histologically to determine if functional deficits correlate with anatomical pathology. If WNV infection adversely affects central breathing function, it would represent a paradigm shift for the neurological mechanism of pathogenesis for viral encephalitis. Importantly, results of this project will provide supporting data for an IRB application to measure respiratory function in WNV-infected human subjects in a forthcoming project