Traumatic Painful Neuropathy and Calcium Signaling

描述（由申请人提供）：神经损伤引起的疼痛伴随着各种各样的疾病，如创伤、手术切口和截肢、炎症、HIV/AIDS和癌症，目前可用的方法治疗不足。初级感觉神经元，包括它们在背根神经节（DRG）中的胞体，是病理学的关键部位，但它们作为治疗靶点的潜力尚未被追求。我们以前已经表明，周围神经损伤导致内向钙流（伊卡）的损失，提高感觉神经元放电，并有助于大鼠的神经病理性疼痛行为。目前提出的研究将扩展这些发现。具体来说，我们的第一个目的是研究新的理论，神经损伤引起痛觉过敏通过抑制活性的钙调蛋白激酶II，神经元频率信息的分子解码器。Ca 2+通道允许随着pCaMKII减少而减少的Ca 2+向内通量。我们已经建立了低伊卡和兴奋性增加之间的密切联系。因此，损伤后的神经元激活导致传入冲动的更大爆发和放大的疼痛体验。因此，我们将通过定量损伤后CaMKII蛋白和功能来测试这一总体假设。此外，我们将使用药理学和遗传策略来阻断和激活CaMKII，以研究其在调节神经元电生理学中的作用。我们的第二个目的是确定CaMKII对细胞内Ca 2+信号的影响。尽管Ca 2+在控制神经元功能中的核心作用，但对神经损伤和CaMKII相关变化对塑造Ca 2+信号的关键过程的影响的研究很少。因此，我们将检查受伤和对照大鼠中的Ca 2+管理，同时从药理学角度改变CaMKII活性并通过siRNA表达敲减CaMKII。将检查特定的Ca 2+摄取和释放途径，同时测量亚细胞区室中的Ca 2+。在我们的第三个目标中，CaMKII调节Ca 2+在疼痛中的重要性将通过在特定DRG内选择性遗传和药理学调节CaMKII活性期间测量大鼠的疼痛行为来直接测试。对公共卫生的重要性：该项目将更好地了解神经损伤如何导致慢性疼痛。这一新的知识可能会导致选择性地传递到周围神经的治疗方法的发展，以纠正异常的Ca 2+信号传导，从而缓解神经损伤疼痛。

DESCRIPTION (provided by applicant): Pain caused by nerve injury accompanies a wide variety of conditions such as trauma, surgical incision and amputation, inflammation, HIV/AIDS and cancer, and is inadequately treated by currently available methods. Primary sensory neurons, including their somata in the dorsal root ganglia (DRG), are critical sites of pathology, yet their potential as a therapeutic target has not been pursued. We have previously shown peripheral nerve injury causes loss of inward Ca2+ flux (ICa) that elevates sensory neuron firing and contributes to neuropathic pain behavior in rats. The currently proposed research will extend these findings. Specifically, our FIRST AIM is to examine the novel theory that nerve injury causes hyperalgesia by depressing the activity of CaMKII, a molecular decoder of neuronal frequency information. Ca2+ channels admit a diminished inward flux of Ca2+ as pCaMKII diminishes. We have established a strong link between low ICa and increased excitability. Thus, neuronal activation after injury results in a greater burst of afferent impulses and an amplified pain experience. Accordingly, we will test this overall hypothesis by quantifying CaMKII protein and function after injury. Further, we will use pharmacologic and genetic strategies to block and activate CaMKII to examine its role in regulating neuronal electrophysiology. Our SECOND AIM is to determine the effect of CaMKII on the intracellular Ca2+ signal. Despite the central role of Ca2+ in controlling neuronal function, there has been minimal investigation of the influence of nerve injury and associated changes in CaMKII on the critical processes that shape the Ca2+ signal. Accordingly, we will examine Ca2+ management in injured and control rats while altering CaMKII activity pharmacologically and by CaMKII knockdown through siRNA expression. Specific Ca2+ uptake and release pathways will be examined while measuring Ca2+ in subcellular compartments. In our THIRD AIM, the importance of CaMKII regulation of Ca2+ in pain will be directly tested by measuring pain behavior in rats during selective genetic and pharmacologic modulation of CaMKII activity within specific DRGs. Importance to Public Health: This project will provide better understanding of how nerve injury causes chronic pain. This new knowledge may lead to the development of therapies that are delivered selectively to the peripheral nerve, in order to correct abnormal Ca2+ signaling and thereby relieve nerve injury pain.