Mechanism of Calcium Channel Cava2d1 Protein Mediated Neuropathic Pain

描述（由申请人提供）：神经损伤性疼痛，或神经性疼痛，是一种常见的疾病，由于其潜在机制尚不清楚，缺乏特定的治疗药物。周围神经损伤诱导电压门控钙通道a2d-1亚基（Cava2d1）在背根神经节和脊髓中的表达，这种表达与神经性疼痛的发生和维持相关，阻断这种表达可导致神经性疼痛逆转。这表明Cava2d1在脊髓致敏中起关键作用，而脊髓致敏是神经性疼痛的基础。为了进一步探讨损伤诱导的Cava2d1上调介导的脊髓致敏和神经性疼痛的机制，我们计划验证以下假设：(1)损伤诱导的Cava2d1上调与损伤诱导的突触诱导剂、背根神经节和脊髓的血栓反应蛋白-4 （TSP4）相互作用；(2)损伤诱导的Cava2d1和TSP4均通过(3)促进脊髓突触发生参与神经性疼痛的发生和维持。首先，我们将使用Western blots和免疫组织化学技术研究脊髓背侧Cava2d1和TSP4与DRG之间的时空相互作用与神经性伤害感受的关系。其次，我们将比较TSP4对过表达Cava2d1的转基因小鼠和Cava2d1表达升高的脊髓神经损伤大鼠的行为过敏的贡献。最后，我们将确定神经损伤引起的cava2d1和TSP4的共同上调是否会导致脊髓背角突触发生增强，从而导致神经性疼痛。这些研究的完成将使我们能够扩展我们目前对损伤诱导的Cava2d1上调机制及其对神经性疼痛的诱导和维持的贡献的了解。

DESCRIPTION (provided by applicant): Nerve injury-induced pain, or neuropathic pain, is a common disorder lacking specific therapeutic agents due to the fact that underlying mechanisms are poorly understood. Peripheral nerve injury induces voltage-gated calcium channel a2d-1 subunit (Cava2d1) expression in dorsal root ganglia and spinal cord that correlates with neuropathic pain development and maintenance, and blocking such an increase results in neuropathic pain reversal. These suggest that Cava2d1 plays a critical role in spinal sensitization that underlies neuropathic pain. To further explore the mechanism underlying spinal sensitization and neuropathic pain mediated by injury-induced Cava2d1 upregulation, we plan to test the hypotheses that (1) injury-induced upregulation of the Cava2d1 interacts with injury-induced synapse inducer, thrombospondin-4 (TSP4) in dorsal root ganglia and spinal cord; (2) Both injury-induced Cava2d1 and TSP4 contribute to initiation and maintenance of neuropathic pain by (3) promoting spinal synaptogenesis. First, we will examine the spatial and temporal interactions between Cava2d1 and TSP4 in dorsal spinal cord and DRG in relation to neuropathic nociception using Western blots and immunohistochemical techniques. Second, we will compare the contribution of TSP4 to behavioral hypersensitivity observed in transgenic mice overexpressing the Cava2d1 or spinal nerve injured rats with elevated Cava2d1 expression. Finally, we will determine if co-upregulation of Cava2d1and TSP4 by nerve injury leads to enhanced synaptogenesis in the spinal dorsal horn that contributes to neuropathic pain. Completion of these studies will allow us to extend our current knowledge about the mechanisms of injury-induced Cava2d1 upregulation and its contribution to the induction and maintenance of neuropathic pain. PUBLIC HEALTH RELEVANCE: Chronic pain derived from nerve injury, or neuropathic pain, is a common clinical syndrome lacking specific and effective therapeutic agents due to the fact that its cellular mechanisms are poorly understood. Existing data indicate that injury-induced voltage-gated calcium channel a2d-1 subunit (Cava2d1) in dorsal root ganglia and spinal cord contributes to the development of neuropathic pain. However, mechanisms underlying injury-induced Cava2d1 in neuropathic pain are not known. We hypothesize that elevated Cava2d1 interacts with thrombospondin-4 (TSP4) post injury in promoting synapse formation, and abnormal synapse formation plays a causal role in neuropathic pain. We will test this hypothesis using genetically modified mice, nerve injury models, biochemical, electrophysiological, and behavioral pharmacology approaches. Completion of this study will provide important information for the understanding of neuropathic pain mechanisms and the development of next generation of neuropathic pain medications.