Mechanisms of analgesia by peripheral viral vector insertion of opioid receptors.

描述（由申请人提供）：神经性疼痛是一种高度流行且严重令人痛苦的疾病，被认为是由外周神经纤维的自发活动和敏化引起的，特别是从外周发出疼痛信号的伤害感受器。阿片类药物治疗已被证明在临床上有效减轻神经性疼痛;然而，其中枢神经系统效应，包括镇静、认知功能受损和滥用可能性，限制了其在患者护理中的有用性。来自致敏神经纤维的输入可导致脊髓对热和机械刺激的处理改变（中枢致敏）。来自神经纤维上的阿片受体激活的镇痛引起神经肽和神经递质释放的减少以及疼痛信号向大脑的传播的抑制。先前的研究已经表明，使用表达μ-阿片受体（莫尔）的重组单纯疱疹-1（HSV-1）病毒载体的基因治疗增加了外周神经纤维上的莫尔表达，并增强了啮齿动物中阿片治疗后的热痛镇痛。目前尚不清楚阿片受体病毒载体治疗的镇痛作用是在伤害感受器的外周还是中枢终末介导的。拟议的实验探索通过病毒载体治疗减轻疼痛的机制。1）确定在神经病动物中，在应用吗啡后，外周神经纤维中MORs的过表达是否增强阿片类物质敏感性并降低初级传入神经元对伤害性刺激的反应。在这些实验中，我们将用HSV-1病毒载体接种慢性压迫性损伤（CCI）小鼠的后爪，所述HSV-1病毒载体含有用于莫尔（SG莫尔）、反义方向的μ-阿片受体（SGAMOR）或作为对照的β-半乳糖苷酶基因（SGZ）的构建体。我们将采用单纤维皮肤神经记录技术来研究基因治疗后阿片类镇痛的外周机制。该建议的假设是，吗啡将1）大大降低外周伤害感受器中伤害性刺激的反应和2）在莫尔病毒载体治疗后减少神经病（CCI）动物中来自伤害感受器的自发活动。靶向外周伤害感受器而不影响中枢神经系统的阿片类药物可能能够减轻疼痛并防止目前许多阿片类药物治疗中出现的不良副作用。该项目的未来长期目标是使用莫尔基因治疗人类慢性和神经性疼痛。

DESCRIPTION (provided by applicant): Neuropathic pain is a highly prevalent and severely distressing condition thought to result from spontaneous activity and sensitization of peripheral nerve fibers, especially nociceptors that signal pain from the periphery. Opioid therapy has been shown to be effective in attenuating neuropathic pain clinically; however their central nervous system effects including sedation, impaired cognitive function and abuse potential limit their usefulness in patient care. Input from sensitized nerve fibers can result in an altered spinal cord processing of thermal and mechanical stimuli (central sensitization). Analgesia from opioid receptor activation on nerve fibers causes a decrease of neuropeptide and neurotransmitter release and inhibition of pain signal propagation to the brain. Previous studies have shown that gene therapy treatment using recombinant herpes simplex-1 (HSV-1) viral vector expressing the mu-opioid receptor (MOR) increases MOR expression on peripheral nerve fibers and enhances heat pain analgesia after opioid treatment in rodents. It is unknown if the analgesia from opioid receptor viral vector therapy is mediated at the peripheral or central terminals of nociceptors. The proposed experiments explore the mechanisms of pain reduction through viral vector therapy. The specific aim outlined in this proposal is: 1) To determine if over-expression of MORs in peripheral nerve fibers enhances opioid sensitivity and decreases primary afferent neuron responses to noxious stimulation post morphine application in neuropathic animals. In these experiments we will inoculate the hindpaw of chronic constriction injury (CCI) mice with an HSV-1 viral vector containing either the construct for either the MOR (SGMOR), the μ-opioid receptor in the anti-sense direction (SGAMOR) or the β-galactosidase gene (SGZ) as a control. We will implement single fiber skin nerve recordings to investigate the peripheral mechanisms of opiate analgesia after gene therapy. The hypotheses of the proposal are that morphine will 1) greatly decrease responses of noxious stimulation in peripheral nociceptors and 2) reduce spontaneous activity from nociceptors in neuropathic (CCI) animals after MOR viral vector therapy. Opioid drugs that target peripheral nociceptors without affecting the central nervous system may be able to reduce pain and prevent adverse side effects seen with many current opioid therapies. The future long-term goal of this project is to use MOR gene therapy for chronic and neuropathic pain conditions in humans.