Traumatic Painful Neuropathy and Calcium Signaling

描述(申请人提供)：神经损伤引起的疼痛伴随着多种情况，如创伤、外科手术切开和截肢、炎症、艾滋病毒/艾滋病和癌症，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，是病理的关键部位，但它们作为治疗靶点的潜力尚未被发掘。我们以前已经证明，周围神经损伤会导致内向钙离子通量(ICA)的丧失，这会增加感觉神经元的放电，并导致大鼠神经病理性疼痛行为。目前提出的研究将扩展这些发现。具体地说，我们的第一个目标是检验神经损伤通过抑制CaMKII的活性而导致痛敏的新理论，CaMKII是神经元频率信息的分子解码器。随着pCaMKII的减少，钙离子通道允许钙离子内流减少。我们已经在低ICA和高兴奋性之间建立了强有力的联系。因此，损伤后神经元的激活会导致更大的传入冲动爆发和放大的疼痛体验。因此，我们将通过量化损伤后的CaMKII蛋白和功能来检验这一总体假设。此外，我们将使用药理学和遗传学策略来阻断和激活CaMKII，以检测其在调节神经元电生理中的作用。我们的第二个目标是确定CaMKII对细胞内钙信号的影响。尽管Ca~(2+)在控制神经功能中起着中心作用，但关于神经损伤及其相关的CaMKII变化对形成Ca~(2+)信号的关键过程的影响的研究还很少。因此，我们将研究损伤和对照大鼠的钙管理，同时从药理上改变CaMKII的活性，并通过siRNA表达通过CaMKII基因敲除来改变CaMKII的活性。在测量亚细胞内的钙离子时，将检测特定的钙吸收和释放途径。在我们的第三个目标中，将通过测量大鼠在特定DRG内对CaMKII活性的选择性遗传和药物调节期间的疼痛行为来直接测试CaMKII对疼痛中钙调节的重要性。对公众健康的重要性：这个项目将提供对神经损伤如何导致慢性疼痛的更好理解。这一新知识可能会导致有选择地向周围神经输送治疗方法的发展，以纠正异常的钙信号，从而减轻神经损伤疼痛。

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.