Analysis of the vagal afferent innervation of the mouse colon

小鼠结肠迷走神经传入神经支配分析

• 批准号: RGPIN-2021-02557
• 负责人: Lomax, Alan
• 金额: $ 2.62万
• 依托单位: Queen's University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2021
• 资助国家: 加拿大
• 起止时间: 2021-01-01 至 2022-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=741835
• 关键词: Analysis; vagal; afferent; innervation; mouse

Information about the state of the colon is conveyed to the central nervous system by two afferent pathways: the spinal afferent pathway and the vagal afferent pathway. Spinal afferent pathways from the colon have been intensely studied due to their involvement in the perception of noxious stimuli that contribute to pain. The vagal afferent innervation of visceral organs is an evolutionarily ancient branch of the nervous system whose functions are well understood in most organs. However, much less attention has been paid to the vagal afferent innervation of the colon. Recently published findings have suggested the vagal afferent innervation of the colon is a vital conduit of interactions between the gut microbiota and the brain, and in activating the cholinergic anti-inflammatory pathway. However, direct evidence in support of these roles is currently lacking, as is information on the structure of the vagal afferent innervation of the colon. Our preliminary data suggest that the vagal innervation of the colon is more extensive than previously suspected and that it detects changes in microbiota composition and immune system activation. We therefore propose two aims to characterise the anatomy and physiology of the vagal afferent innervation of the colon. Aim 1. Characterise the neuroanatomy of the vagal afferent innervation of the colon. Using retrograde labelling of vagal afferent axons, we will quantify how many cell bodies of neurons in the nodose ganglia (NG) innervate the proximal and distal colon and determine whether many NG neurons innervate both sites. We will utilize anterograde tracing to determine the localization of vagal afferent terminals in the colonic mucosa and smooth muscle layers. The localisation of these afferent terminals will provide insight into what physiological parameters are most likely to be monitored by the vagal afferent innervation of the colon. Aim 2. Determine the role of vagal afferent neurons in detecting disruptions of colonic homeostasis. We will examine whether gut microbial dysbiosis and colonic inflammation affect the activity of vagal afferent neurons using electrophysiology and an immunohistochemical marker of neuronal activation, c-fos immunoreactivity. If we observe that colitis or microbial dysbiosis leads to activation of NG neurons and downstream neurons, we will identify the ionic mechanisms involved using patch clamp, and will sever the vagus nerve to determine whether the peripheral terminals of vagal afferent neurons are essential for these responses. We will also attempt to identify the microbial or host-derived mediators involved. The proposed studies will be the first comprehensive analysis of the vagal afferent innervation of the colon and will facilitate mechanistic studies of the role of the gut-brain axis in colonic homeostasis and in mediating microbial influences on the brain.

有关结肠状态的信息通过两种传入途径传达给中枢神经系统：脊柱传入途径和迷走神经传入途径。由于它们参与了导致疼痛的有害刺激的感知，因此对结肠的脊柱传入途径进行了深入研究。内脏器官的迷走神经支配是神经系统的进化古老的分支，在大多数器官中都可以很好地理解其功能。但是，对结肠的迷走神经支配的关注要少得多。最近发表的发现表明，结肠的迷走神经支配是肠道菌群与大脑之间相互作用的重要渠道，并激活了胆碱能抗炎途径。但是，目前缺乏支持这些角色的直接证据，以及有关迷走神经神经支配的结构的信息。我们的初步数据表明，结肠的迷走神经支配比以前怀疑的更广泛，并且检测到微生物群成分和免疫系统激活的变化。因此，我们提出了两个目的，以表征结肠迷走神经神经神经神经的解剖学和生理。目的1。表征结肠迷走神经神经神经神经的神经解剖学。使用迷走神经传入轴突的逆行标记，我们将量化淋巴结神经节（NG）中有多少个神经元的细胞体支配近端和远端结肠，并确定许多NG神经元是否支配了这两个位点。我们将利用顺行追踪来确定迷走神经传入末端在结肠粘膜和平滑肌层中的定位。这些传入终端的定位将提供深入了解哪些生理参数最有可能通过结肠的迷走神经支配来监测哪些生理参数。 目标2。确定迷走神经神经元在检测结肠体内稳态中断中的作用。我们将研究使用电生理学和神经元激活，C-FOS免疫反应性的免疫组织化学标志物是否会影响迷走神经神经元的活性。如果我们观察到结肠炎或微生物失调会导致NG神经元和下游神经元的激活，我们将确定使用斑块夹涉及的离子机制，并将破坏迷走神经以确定神经传入神经元的周围末端是否对于这些反应至关重要。我们还将尝试确定所涉及的微生物或宿主衍生的介体。 拟议的研究将是对结肠的迷走神经支配的首次综合分析，并将促进肠脑轴在结肠体内稳态中的作用以及介导微生物对大脑的影响。