Molecular characterization of expiratory breathing-related interneurons in mammals

项目总结 呼吸是使肺部通风以进行气体交换的重要行为，从而保持健康和 动态平衡。休息时的呼吸由主动吸气(吸气)和被动呼气(呼气)组成。 随着呼吸需求的增加，呼气变得活跃，以增加通气量。要了解神经 关于呼吸的基础和控制，我们必须能够解释活动背后的两种机制 灵感和那些潜在的主动到期。但目前存在着一个巨大的差距：机制 对于灵感，人们在多个层次的分析中都很好地理解了，但主动呼气的机制 几乎完全不为人知。既不是潜在的节律神经元，也不是它们的空间组织 已经被详细调查过了。目前我们所知道的就是呼气节律很可能出现 从延髓嘴外侧的副面区域的多功能区域发出。这项工程将架起 这一知识缺口并识别导致主动呼气的神经元类别，绘制出 呼气节律网络，并确定它们的功能。 我们的项目遵循合乎逻辑的步骤：首先，对面旁间神经元的转录体进行测序，并确定 高表达的转录本定义神经元亚型；第二，绘制其亚型的神经元的边界 在步骤1中定义；第三，通过特定细胞群询问它们的呼气功能 清醒正常成年小鼠的光刺激和光抑制实验。 这个项目的结果将是一个明确定义的呼气呼吸运动的神经核心， 在分子遗传学分析水平上，面旁间神经元的原始和注释转录本 在公共领域自由传播(通过国家研究中心的基因表达总览 生物技术信息)，以及平衡地理解和解释两者背后的机制 积极的灵感和积极的呼气。 扭动、咀嚼和吸气的呼吸节奏有很大不同的机制。这个项目 将描述第四种口腔面部振动--主动呼气--它将推动感觉运动 神经科学。这项目前的项目将揭开呼气致心律失常神经元是否源于 Atoh1表达前体引起PHOX2B表达中枢呼吸化学传感器， 表达Krox20/Egr2的祖细胞，或在后脑发育的另一种尚未确定的细胞类别 菱形核3和5(R3/R5)。这一新知识将增强我们目前对 呼吸中枢模式发生器(BCPG)的开发和组装。最后，鉴于整个 BCPG对阿片类药物引起的呼吸抑制(OIRD)敏感，主动呼气振荡器是 令人惊讶的是对阿片类药物不敏感。这个项目中的新知识可能会被用来提供急性治疗 阿片类药物过量和长期治疗战略，以保护正在康复的阿片成瘾者免受OIRD的伤害。

PROJECT SUMMARY Breathing is important behavior that ventilates the lungs for gas exchange, thus maintaining health and homeostasis. Breathing at rest consists of active inspiration (inhalation) but expiration (exhalation) is passive. Expiration becomes active to increase ventilation as respiratory demand increases. To understand the neural bases and control of breathing, we must be able to explain both the mechanisms that underlie active inspiration and those underlying active expiration. But there is a massive disparity at present: the mechanisms for inspiration are very well understood at multiple levels of analysis, but the mechanisms for active expiration remain almost entirely unknown. Neither the underlying rhythmogenic neurons nor their spatial organization have been investigated in any detail. All we do know at present is that expiratory rhythm probably emerges from a multifunctional region in the parafacial region of the rostral-lateral medulla. This project would bridge that knowledge gap and identify the neuron class giving rise to active expiration, map the borders of the expiratory rhythmogenic network, and establish their functionality definitively. Our project follows logical steps: first, sequence the transcriptomes of parafacial interneurons and identify highly expressed transcripts to define neuronal subtypes; second, map the borders of neurons whose subtypes were defined in step 1; and third, interrogate their expiratory function via cell population-specific photostimulation and photoinhibition experiments in awake intact adult mice. The upshot of this project will be a well-defined neural core for expiratory breathing movements, characterized at the molecular-genetic level of analysis, raw and annotated transcriptomes of parafacial interneurons disseminated freely in the public domain (via the Gene Expression Omnibus of the National Center for Biotechnology information), and a balanced understanding and explanation of the mechanisms underlying both active inspiration and active expiration. There are widely disparate mechanisms for whisking, chewing, and inspiratory breathing rhythms. This project would describe a fourth orofacial oscillation – active expiration – which would advance sensorimotor neuroscience. This present project would unravel whether expiratory rhythmogenic neurons are derived from Atoh1-expressing precursors that give rise to Phox2b-expressing central respiratory chemosensors, Krox20/Egr2-expressing progenitors, or another yet-to-be-identified cell class that develops in hindbrain rhombomeres 3 and 5 (r3/r5). This new knowledge would augment our current understanding of the development and assembly of the breathing central pattern generator (bCPG). Finally, whereas the entire bCPG is susceptible to opioid-induced respiratory depression (OIRD), the active expiratory oscillator is surprisingly opioid-insensitive. New knowledge in this project may be leveraged to provide acute treatments for opioid overdose and long-term treatment strategies that protect recovering opioid addicts from OIRD.