Neuronal Plasticity and Signaling in Neuropathic Pain

项目概述：脊髓水平活动依赖性突触可塑性对外伤性神经损伤和手术引起的神经性疼痛的发展至关重要。脊髓背角的n -甲基- d -天冬氨酸（NMDA）受体在神经性疼痛的中枢致敏和维持中起关键作用。然而，神经损伤后脊髓中NMDA受体活性增强的机制尚不清楚。虽然已知神经损伤后NMDA受体磷酸化增加，但神经性疼痛中NMDA受体活性增加的上游机制仍有待确定。在我们的初步研究中，我们发现脊髓蛋白激酶CK2的抑制完全逆转了NMDA受体活性的增加，并产生了神经损伤引起的异位性疼痛的持久衰减。在本应用中，我们将使用神经性疼痛的动物模型来验证神经损伤增加脊髓中CK2活性的中心假设，这促进了NMDA受体NR1亚基的磷酸化，并增强了NMDA介导的神经性疼痛突触传递。该应用程序的具体目的是：(1)确定CK2（磷酸化）和钙调磷酸酶（去磷酸化）活性之间的不平衡在脊髓水平nmda介导的突触传递增强和神经性疼痛中的作用；(2)确定CK2活性水平及其在神经损伤后脊髓NMDA受体NR1亚基磷酸化增加中的作用；(3)确定NR1和CK2亚基之间的蛋白相互作用，CK2在NMDA受体上的磷酸化位点，以及它们在神经性疼痛中对NMDA受体活性升高的调节作用。CK2在神经损伤诱导的脊髓突触可塑性发展中的作用尚未被认识到。我们期望这项研究的新发现不仅对我们对神经性疼痛的分子机制的理解的显著提高，而且对神经性疼痛治疗新策略的发展至关重要。由于直接阻断NMDA受体会产生难以忍受的副作用，因此靶向CK2及其特异性NMDA受体磷酸化位点可能是降低NMDA受体活性和神经性疼痛的新策略。

DESCRIPTION (provided by applicant): Neuronal Plasticity and Signaling in Neuropathic Pain Project Summary Activity-dependent synaptic plasticity at the spinal cord level is fundamentally important to the development of neuropathic pain caused by traumatic nerve injury and surgery. N-methyl-D-aspartate (NMDA) receptors in the spinal dorsal horn are critically involved in central sensitization and maintenance of neuropathic pain. However, the mechanisms of potentiated NMDA receptor activity in the spinal cord after nerve injury remain poorly understood. Although increased phosphorylation of NMDA receptors after nerve injury is known, the upstream mechanisms of increased NMDA receptor activity in neuropathic pain remain to be determined. In our preliminary studies, we found that inhibition of the protein kinase CK2 in the spinal cord completely reversed increased NMDA receptor activity and produced long-lasting attenuation of allodynia caused by nerve injury. In this application, we will use an animal model of neuropathic pain to test the central hypothesis that nerve injury increases CK2 activity in the spinal cord, which facilitates phosphorylation of the NR1 subunit of NMDA receptors and potentiates NMDA-mediated synaptic transmission in neuropathic pain. The specific aims of this application are to (1) define the role of imbalance between the CK2(phosphorylation) and calcineurin(de-phosphorylation) activities in augmented NMDA-mediated synaptic transmission at the spinal cord level and neuropathic pain; (2) determine the level of CK2 activity and its role in increased phosphorylation of the NR1 subunit of NMDA receptors in the spinal cord after nerve injury; and (3) identify the protein interaction between NR1 and CK2 subunits, the CK2 phosphorylation sites on the NMDA receptor, and their roles in regulation of increased NMDA receptor activity in neuropathic pain. The role of CK2 in the development of synaptic plasticity in the spinal cord induced by nerve injury has not been recognized previously. We expect that new findings from this proposal will be critical not only to the significant improvement of our understanding of the molecular mechanisms of neuropathic pain but also to the development of new strategies to treat neuropathic pain. Because directly blocking NMDA receptors produces intolerable side effects, targeting CK2 and its specific NMDA receptor phosphorylation sites could represent novel strategies for reducing the NMDA receptor activity and neuropathic pain.