Opioid and Non-Opioid Actions of Dynorphin in Pain

强啡肽在疼痛中的阿片类和非阿片类药物作用

• 批准号: 6628343
• 负责人: Frank Porreca
• 金额: $ 53.09万
• 依托单位: UNIVERSITY OF ARIZONA
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-01 至 2006-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6628343
• 关键词: afferent nerve; calcitonin gene related peptide; calcium flux; central neural pathway /tract; chronic pain; dynorphins; embryo /fetus tissue /cell culture; excitatory aminoacid; gene expression; hyperalgesia; immunologic assay /test; laboratory rat; nerve injury; neural information processing; neural plasticity; neuroanatomy; neurochemistry; neuropathology; neurophysiology; neurotransmitter transport; protein kinase C; protein localization; protein structure function; spinal cord surgery; spinal ganglion

DESCRIPTION:(from applicant's abstract): One of the most significant health problems in our country is the inadequate treatment of pain, especially the chronic abnormal pains often associated with nerve injury (neuropathic pain). Injuries to nerves in experimental models of neuropathic pain elicit peripheral, spinal and supraspinal neural plasticity characterized in part by increased expression of spinal dynorphin. Progress made in our previous funding period suggests that enhanced expression of dynorphin resulting from experimental nerve injury acts in a non-opioid fashion to promote pain. Some of the relevant observations which support a pronociceptive role of dynorphin in the post-nerve injury state include: (a) spatial and temporal correlation of increased spinal dynorphin expression across multiple, anatomically relevant spinal segments following nerve injury, (b) inhibition of nerve-injury induced pain by antiserum to dynorphin, but not control serum, and (c) demonstration of sustained nerve-injury induced pain in wild-type (WT), but not in prodynorphin "knock-out" (KO) mice. Our studies show that dynorphin (2-17) (which does not bind to opioid receptors) promotes calcium accumulation in DRG cells in culture and activates protein kinase C (PKC) in spinal cord. Moreover, des-Tyr fragments of dynorphin enhance capsaicin-stimulated CGRP release in DRG cells and in spinal cord tissue preparations. The overall hypothesis of our work is that spinal dynorphin is pronociceptive and it a critical mediator which serves to maintain pathological post-nerve injury pain. Specifically we propose a mechanism by which dynorphin maintains post-nerve injury pain by increasing spinal excitability, in part, by enhancing the release of excitatory transmitters. Our aims are designed to systematically test this hypothesized mechanism. Aim 1 will determine whether nerve-injury induced changes in dynorphin expression are the result of modulatory influences from supraspinal sites. Aim 2 will focus on measurement of nerve-injury induced release of dynorphin at the spinal level. Aim 3 will use cultured DRG cells to test if dynorphin enhances evoked CGRP release through activation of PKC. Aim 4 will use spinal cord tissue preparations taken from sham- or nerve-injured rats, as well as from sham- or nerve-injured WT and prodynorphin KO mice to determine the role of endogenous, pathological levels of dynorphin on basal and evoked CGRP release. Aim 5 will focus on the role of dynorphin in the release of excitatory amino acids in sham-operated and nerve-injured rats. The experiments in Aim 5 will be carried out in the laboratory of Dr. Tony Yaksh through a Consortium Arrangement. All of these studies focus on the central hypothesis of pronociceptive actions of dynorphin in the post nerve-injury state and test a proposed mechanism which addresses how dynorphin may act under conditions of nerve-injury to maintain pain. As most clinical conditions of neuropathic pain are treated in the post-injury (i.e., maintenance) state, such information may allow approaches to limit or reverse the pathological actions of dynorphin in maintaining neuropathic pain.

描述：（来自申请人摘要）： 我国最严重的健康问题之一是缺乏足够的医疗保健。 治疗疼痛，尤其是慢性异常疼痛，通常与 神经性疼痛（neuropathic pain）实验模型中的神经损伤 神经病理性疼痛引起外周、脊髓和脊髓上神经可塑性 其特征部分在于脊髓强啡肽的表达增加。进展 我们在上一个资助期提出的建议表明， 实验性神经损伤引起的强啡肽以非阿片类药物的方式发挥作用 以促进疼痛。一些相关的意见，支持一个 强啡肽在神经损伤后状态中的感受性作用包括：（a） 脊髓强啡肽表达增加的时空相关性 在神经损伤后穿过多个解剖学上相关的脊柱节段， (b)强啡肽抗血清对神经损伤性疼痛的抑制作用， 对照血清，和（c）在小鼠中证实持续的神经损伤诱导的疼痛。 野生型（WT），但在强啡肽原“敲除”（KO）小鼠中没有。我们的研究表明 强啡肽（2-17）（不与阿片受体结合）促进 在培养的DRG细胞中钙积累并激活蛋白激酶C (PKC)在脊髓中。此外，强啡肽的脱-Tyr片段增强了 辣椒素刺激DRG细胞和脊髓组织中CGRP的释放 准备工作。我们工作的总体假设是脊髓强啡肽是 pronociceptive和它的一个关键的调解人，这有助于维持病理 神经损伤后疼痛具体来说，我们提出了一种机制， 通过增加脊髓兴奋性来维持神经损伤后疼痛，部分原因是 增强兴奋性递质的释放。我们的目标是 系统地测试这个假设的机制。目标1将决定是否 神经损伤诱导的强啡肽表达变化是以下因素的结果： 来自脊髓上部位的调节作用。目标2将侧重于测量 神经损伤引起的脊髓水平强啡肽释放。目标3将 使用培养的DRG细胞来测试强啡肽是否增强诱发的CGRP释放 通过激活PKC。Aim 4将使用脊髓组织制备物 来自假损伤或神经损伤的大鼠，以及来自假损伤或神经损伤的WT和 测定强啡肽原基因敲除小鼠内源性作用、病理水平 强啡肽对基础和诱发CGRP释放的影响。目标5将侧重于 强啡肽在假手术和 神经损伤的老鼠目标5中的实验将在 Tony Yaksh博士的实验室通过财团安排。所有这些 研究集中在强啡肽的原伤害感受作用的中心假说 在神经损伤后的状态，并测试提出的机制， 强啡肽如何在神经损伤的情况下起作用以维持疼痛。作为 大多数神经性疼痛的临床病症在损伤后 (i.e.,维护）状态，这样的信息可以允许限制或 逆转强啡肽在维持神经病理性疼痛中的病理作用。