Mechanism of Calcium Channel Cava2d1 Protein Mediated Neuropathic Pain

描述(申请人提供)：神经损伤引起的疼痛，或神经病理性疼痛，是一种常见的疾病，缺乏特定的治疗药物，因为其潜在的机制知之甚少。周围神经损伤诱导背根神经节和脊髓电压门控性钙通道a2d-1亚单位(Cava2d1)表达，与神经病理性疼痛的发生和维持相关，阻断这种增加可导致神经病理性疼痛逆转。这些结果表明，Cava2d1在神经病理性疼痛的脊髓敏化中起着关键作用。为了进一步探讨损伤诱导的Cava2d1上调介导的脊髓敏化和神经病理性疼痛的机制，我们计划检验以下假设：(1)损伤诱导的Cava2d1上调与损伤诱导的突触诱导物--背根神经节和脊髓中的血栓反应蛋白-4(TSP4)相互作用；(2)损伤诱导的Cava2d1和TSP4均通过促进脊髓突触发生而参与神经病理性疼痛的启动和维持。首先，我们将利用Western blotts和免疫组织化学技术研究脊髓背侧和背根节中Cava2d1和TSP4的时空相互作用与神经病理性伤害性感受的关系。其次，我们将比较TSP4在过量表达Cava2d1的转基因小鼠和高表达Cava2d1的脊神经损伤大鼠中观察到的行为超敏反应的作用。最后，我们将确定神经损伤是否导致Cava2d1和TSP4的共同上调导致脊髓背角突触生成增强，从而导致神经病理性疼痛。这些研究的完成将使我们能够扩展我们目前关于损伤诱导的Cava2d1上调的机制及其在神经病理性疼痛的诱导和维持中的作用的现有知识。 公共卫生相关性：神经损伤引起的慢性疼痛，或神经病理性疼痛，是一种常见的临床综合征，由于其细胞机制尚不清楚，缺乏特定和有效的治疗药物。已有研究表明，损伤诱导的背根节和脊髓电压门控性钙通道a2d-1亚单位(Cava2d1)参与神经病理性疼痛的发生。然而，损伤诱导的Cava2d1在神经病理性疼痛中的潜在机制尚不清楚。我们推测，损伤后升高的Cava2d1与血栓反应蛋白-4(TSP4)相互作用，促进突触形成，突触形成异常在神经病理性疼痛中起因果作用。我们将使用转基因小鼠、神经损伤模型、生化、电生理和行为药理学方法来验证这一假设。这项研究的完成将为了解神经病理性疼痛的机制和开发下一代神经病理性疼痛药物提供重要信息。

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.