Roles of mechanosensory ion channels in myenteric intrinsic primary afferent neurons

机械感觉离子通道在肌间固有初级传入神经元中的作用

• 批准号: RGPIN-2014-05517
• 负责人: Kunze, Wolfgang
• 金额: $ 1.89万
• 依托单位: McMaster University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2018
• 资助国家: 加拿大
• 起止时间: 2018-01-01 至 2019-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=656137
• 关键词: Roles; mechanosensory; ion; channels; myenteric

The enteric nervous system is an independent division of the autonomic nervous system which contains its own in sensory neurons that respond to gut compression. However, the concept of a complete nervous system contained entirely in the wall of the intestine is still being established and relies in part on showing that there are intrinsic sensory neurons in the gut and studying their functional properties. Of particular importance in relation to the contracting gut and its propulsive reflexes is the excitability intrinsic mechanosensitive sensory neurons. We know that peristaltic propagated motor complexes depend on intrinsic myenteric sensory neurons, because experimentally silencing these neurons causes inhibition of propulsion, stasis and death. Although many types of myenteric neurons (and other types of cells) have been shown to respond to stretch or defamation, we have identified a type of chemosensitive myenteric intrinsic primary afferent neuron (IPAN) whose firing rate is modulated by s compression. Moreover, we provide evidence for stretch sensitive channels (somatic BK and axonic cationic channels) in IPANs, and no equivalent has so far been found in other types of myenteric neurons. We have thus provided beginning experimental data for molecular basis for a mechanosensory role for IPANs. Our experiments are designed to systematically study the properties of stretch sensitive channels in IPANs to help understand these sensory neurons integrate mechanical signals with other determinants of their excitability.*Stretch sensitive ion channels provide the link between gut movement and how IPANs sense and respond to distension to initiate peristalsis. We have already uniquely recorded currents from mechanosensitive BK channels in myenteric IPANs and shown that BK opening inhibits neuron firing. We now plan to quantitatively measure BK channel currents to make a best fit model of its opening and closing properties. This will help us in understanding how determinants of channel opening interact to influence the overall mechanosensitive current. We establish if BK channel opening is affected by intracellular calcium, gut hormones, with each fact integrated into the model. IPANs, unlike spinal or vagal sensory neurons. Receive synaptic input adding another dimension to their functional repertoire. The effect effects of synaptic input on BK channels will also be determined experimentally. *Excitatory stretch sensitive channels on the sensory neuron's axons have been indirectly inferred from our experiments. These are extremely important in initiating sensory neuron firing and thus peristalsis yet they have not been identified as to their identity or response characteristics. We will perform stimulus-response experiments and ion substitution experiments to identify for the first time which neuronal channels initiate peristalsis. This work will provide the first molecular physiological study of the mechanisms that control of gut motility at the neurone cellular level and will expand the understanding of how the intestine responds to stimuli, independent of the central or other autonomic nervous systems. Because little is presently known about gut IPAN mechanotransduction compared to other sensory systems, our work will help increase knowledge in gut sensory physiology at a level of detail not presently available. This work will benefit Canadian gut sensory neuroscience research in which my laboratory is at the forefront of myenteric neuron sensory physiology.

肠神经系统是自主神经系统的一个独立分支，自主神经系统包含其自身的对肠道压迫做出反应的感觉神经元。然而，完全包含在肠壁中的完整神经系统的概念仍在建立中，部分依赖于显示肠道中存在内在感觉神经元并研究其功能特性。与收缩肠道及其推进反射相关的特别重要的是内在机械敏感感觉神经元的兴奋性。我们知道，蠕动传播的运动复合体依赖于内在肌间感觉神经元，因为实验沉默这些神经元导致推进抑制，停滞和死亡。虽然许多类型的肌间神经元（和其他类型的细胞）已被证明对拉伸或破坏作出反应，我们已经确定了一种类型的化学敏感性肌间内在初级传入神经元（IPAN），其放电率由s压缩调制。此外，我们提供了IPAN中拉伸敏感通道（体细胞BK和轴突阳离子通道）的证据，到目前为止，在其他类型的肌间神经元中还没有发现类似的通道。因此，我们提供了开始的实验数据的分子基础的机械感觉作用的IPAN。我们的实验旨在系统地研究IPAN中拉伸敏感通道的特性，以帮助理解这些感觉神经元将机械信号与其兴奋性的其他决定因素整合在一起。拉伸敏感离子通道提供了肠道运动与IPAN如何感知和响应膨胀以启动膨胀之间的联系。我们已经在肌间IPAN中独特地记录了来自机械敏感性BK通道的电流，并表明BK开放抑制神经元放电。我们现在计划定量测量BK通道电流，以建立其开放和关闭特性的最佳拟合模型。这将有助于我们理解通道开放的决定因素如何相互作用以影响整体机械敏感电流。我们确定BK通道开放是否受到细胞内钙、肠道激素的影响，并将每个事实整合到模型中。IPAN，不像脊髓或迷走神经感觉神经元。接受突触输入为他们的功能库增加了另一个维度。突触输入对BK通道的效应也将通过实验确定。* 感觉神经元轴突上的兴奋性牵张敏感通道已经从我们的实验中间接推断出来。这些在启动感觉神经元放电和因此放电中是极其重要的，但它们的身份或反应特征尚未被识别。我们将进行刺激反应实验和离子替代实验，以确定第一次神经元通道启动pathesis。这项工作将提供第一个在神经元细胞水平上控制肠道运动的机制的分子生理学研究，并将扩大对肠道如何独立于中枢或其他自主神经系统对刺激作出反应的理解。由于与其他感觉系统相比，目前对肠道IPAN机械转导知之甚少，我们的工作将有助于在目前尚不具备的细节水平上增加肠道感觉生理学的知识。这项工作将有利于加拿大的肠道感觉神经科学研究，我的实验室是在肌间神经元感觉生理学的最前沿。