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: 2016
• 资助国家: 加拿大
• 起止时间: 2016-01-01 至 2017-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=611685
• 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独立划分，它包含其自主神经元中对肠道压缩反应的感觉神经元。但是，完全包含在肠壁中的完整神经系统的概念仍然建立，并部分依赖于肠道中有内在的感觉神经元并研究其功能特性。与收缩肠道及其推进反射有关的是令人兴奋的内在机械敏感性神经元。我们知道，蠕动传播的运动复合物取决于固有的肌植物感觉神经元，因为对这些神经元进行实验性沉默会导致推进，停滞和死亡的抑制。尽管已证明许多类型的肌植物神经元（以及其他类型的细胞）对拉伸或诽谤做出了反应，但我们已经确定了一种化学敏感性的肌敏感性固有的原始传入神经元（IPAN），其发射速率受S压缩调节。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，在其他类型的肌室神经元中尚未发现等效的证据。因此，我们为IPAN的机理感官作用提供了开始的分子基础实验数据。我们的实验旨在系统地研究IPAN中拉伸灵敏通道的特性，以帮助了解这些感觉神经元将机械信号与其他兴奋性的决定者整合在一起。 伸展敏感的离子通道提供了肠道运动与IPAN感应和对延伸的响应方式之间的联系。我们已经从Myenteric IPAN中的机械敏感BK通道中记录了唯一记录的电流，并表明BK开放抑制了神经输血。现在，我们计划对BK通道电流进行定量测量，以制造其开放和关闭属性的最佳拟合模型。这将有助于我们了解频道开放的决定素如何相互作用以影响整体机械敏感电流。我们确定BK通道的开口是否受细胞内钙，肠激素的影响，每个事实都集成到模型中。与脊柱或迷走性感觉神经元不同。接收突触输入，为其功能曲目添加另一个维度。突触输入对BK通道的影响也将通过实验确定。 从我们的实验中可以间接推断出感觉神经元轴突上的兴奋性拉伸灵敏通道。这些对于启动感觉神经元发射非常重要，因此蠕动尚未确定它们的身份或响应特征。我们将执行刺激反应实验和离子取代实验，以首次识别神经元通道引发蠕动。这项工作将为控制神经元细胞水平的肠道运动的机制提供第一个分子生理研究，并将扩展对肠道对刺激的反应，与中枢或其他自主神经系统无关。由于与其他感觉系统相比，关于肠道IPAN机械转导的肠道机械转导很少，因此我们的工作将有助于在目前无法使用的细节级别上提高肠道感觉生理的知识。这项工作将使加拿大肠道神经科学研究受益，其中我的实验室处于肌室神经感觉生理的最前沿。