ClC-3下调导致DRG神经元兴奋性增高和机械痛敏的机制研究

我们以往的研究表明，外周神经损伤通过TNF-α过表达，上调DRG神经元的电压依赖性钠通道，引起神经病理性疼痛。在国家自然基金青年项目资助下，我们发现外周神经损伤引起DRG神经元ClC-3氯通道下调，敲除ClC-3基因导致DRG神经元兴奋性增高和机械痛敏，提示ClC-3氯通道下调在病理性疼痛中发挥重要作用，但机制不清。我们还发现，敲除ClC-3引起TNF-α表达升高，电压依赖性钠通道电流增大，以此，我们推测ClC-3下调可能通过调控炎症反应，上调钠通道，导致DRG神经元兴奋性升高。本项目拟采用行为学、分子生物学和电生理方法，验证这一设想。研究内容包括：ClC-3下调或敲除后神经元胞内氯浓度的变化，对炎症反应的影响，及对钠通道表达和功能的作用。迄今，有关DRG神经元兴奋性升高导致病理性疼痛的研究主要集中于阳离子通道，本项目将研究阴离子通道的作用，有望揭示病理性疼痛的新机制，发现新的治疗靶点。

Our previous results have revealed that upregulation of voltage-dependent sodium channels induced by TNF-α contributes to neuropathic pain after peripheral nerve injury.Recently, we found that peripheral nerve injury decreased the expression of ClC-3 chloride channel in DRG neurons, ClC-3 knockout enhanced the excitability of DRG neurons and evoked mechanical hyperalgesia, suggesting that downregulation of ClC-3 chloride channel may play an important role in the development of neuropathic pain. However, the underlying mechanisms are not clear. Moreover, we observed that ClC-3 knockout increased TNF-α expression as well as voltage-dependent sodium currents in DRG neurons. Therefore, we hypothesized that increased inflammation and voltage-dependent sodium currents may underlie the enchanced excitability of DRG neurons in ClC-3 knockout mcie. To verify this hypothesis, we will examine the difference of intracellular chloride concentration, inflammatory response, the expression and functions of voltage-dependent sodium channels in DRG neurons between ClC-3 knockout and wild type mice using behavior test, molecular biological method and electrophysiological technique. Since previous studies mainly focused on the function of cation channels in the regulation of neuropathic pain, our present work in the role of anion channel maybe unveil the new mechanisms of neuropathic pain and discover novel therapeutic targets.