Role of peroxynitrite in morphine hyperalgesia and tolerance

描述（由申请人提供）：阿片类药物（如硫酸吗啡）是治疗急性和慢性重度疼痛的最有效镇痛药，但其使用受到对无害和有害刺激的耐受性和超敏反应的限制。阿片类药物引起的痛觉过敏和镇痛耐受的机制尚不清楚。过氧亚硝酸盐（ONOO-）由超氧化物（O2. -）产生和一氧化氮（NO），是一种有效的促炎和促凋亡活性氮物质，现在与痛觉过敏有关。我们的中心假设是，内源性ONOO-是导致吗啡诱导的痛觉过敏和抗伤害耐受的信号事件级联的近端分子。在小鼠中，我们发现，重复给予吗啡导致硝基酪氨酸（NT，ONOO-的标志物）形成。ONOO-的作用通过显示共同施用吗啡与NO合酶抑制剂、O2-清除剂和O2-清除剂来证明。或新的ONOO-分解催化剂减弱NT形成并阻止抗伤害耐受。这些涉及ONOO耐受和抗伤害耐受的关联和因果关系与以下情况一致：1）MnSOD、谷氨酸转运蛋白（GLT-1）和谷氨酰胺合酶（GS）的翻译后硝化; 2）促炎细胞因子的形成增加; 3）氧化DNA损伤和核因子聚（ADP-核糖）聚合酶的激活。抑制ONOO-减弱了这些变化。最后，通过鞘内给药证实了ONOO-分解催化剂全身给药的结果，从而支持其在脊髓水平的作用。三个具体目标将检验我们的假设。具体目标1将定义脊髓ONOO-和吗啡诱导的超敏反应和抗伤害耐受性的发展之间的关联和因果关系。具体目标2将使用药理学和遗传学方法确定NADPH氧化酶作为O2来源的贡献。因此，在吗啡超敏反应和抗伤害性耐受的发展过程中重新形成ONOO-。具体目标3将阐明ONOO-调节痛觉过敏和抗伤害耐受的分子和生化机制。这些研究的结果将确定ONOO-在抗伤害耐受性发展中的重要作用，为ONOO-分解催化剂作为阿片类药物的替代物用于慢性疼痛的治疗提供理论基础。项目叙述：慢性疼痛影响着大约8600万美国人，每年至少花费1000亿美元的医疗费用和降低的工作效率。 阿片类药物（如吗啡）是治疗严重慢性疼痛最有效的镇痛药，但其缓解疼痛的作用在长期给药期间通常会减弱，需要增加剂量，从而降低患者的生活质量。我们的研究将首次确定，用新型药物去除过氧亚硝酸盐，恢复吗啡的止痛作用，开辟了慢性疼痛管理的新前沿，从而改善了相关的社会经济后果。

DESCRIPTION (provided by applicant): Opiates like morphine sulfate are the most effective analgesics for treating acute and chronic severe pain, but their use is limited by development of tolerance and hypersensitivity to innocuous and noxious stimuli. The mechanisms of such opiate-induced hyperalgesia and antinociceptive tolerance are unclear. Peroxynitrite (ONOO-) produced from superoxide (O2.-) and nitric oxide (.NO), is a potent pro-inflammatory and pro- apoptotic reactive nitrogen species now implicated in hyperalgesia. Our central HYPOTHESIS is that endogenous ONOO- is the proximal molecule in a cascade of signaling events leading to morphine-induced hyperalgesia and antinociceptive tolerance. In mice we showed that repeated morphine administration leads to nitrotyrosine (NT, a marker of ONOO-) formation. The role of ONOO- was proven by showing that co- administering morphine with inhibitors of .NO synthase, scavengers of O2.- or novel ONOO- decomposition catalysts attenuated NT formation and prevented antinociceptive tolerance. These associative and causal links involving ONOO- and antinociceptive tolerance coincided with: 1) post-translational nitration of MnSOD, a glutamate transporter (GLT-1), and glutamine synthase (GS); 2) increased formation of pro-inflammatory cytokines; and 3) oxidative DNA damage and activation of the nuclear factor poly(ADP-ribose) polymerase. Inhibiting ONOO- attenuated these changes. Finally, results with systemic administration of ONOO- decomposition catalysts were confirmed by intrathechal dosing, thus supporting its role at the level of the spinal cord. Three Specific Aims will test our hypothesis. Specific Aim 1 will define the associative and causal link between spinal ONOO- and the development of morphine-induced hypersensitivity and antinociceptive tolerance. Specific Aim 2 will identify, using pharmacological and genetic approaches, the contribution of the NADPH oxidase as source of O2.- and thus, de novo ONOO- formation during the development of morphine hypersensitivity and antinociceptive tolerance. Specific Aim 3 will elucidate the molecular and biochemical mechanisms whereby ONOO- modulates hyperalgesia and antinociceptive tolerance. Results from these studies will define the important role of ONOO- in the development of antinociceptive tolerance providing the rationale towards the development of ONOO- decomposition catalysts as adjuncts to opiates for the management of chronic pain. Project Narrative: Chronic pain affects approximately 86 million Americans and cost at least $100 billion annually in medical expenses and reduced work productivity. PUBLIC HEALTH RELEVANCE Opioid drugs such as morphine are the most effective analgesics for treating severe chronic pain, but its pain-relieving action is often diminished during chronic administration, necessitating dose escalation that reduces quality of life for the patient. Our studies will determine for the first time that removal of peroxynitrite with novel agents, restores the pain-relieving action of morphine opening a new frontier in chronic pain management thereby improving the associated socioeconomic consequences.