Role of peroxynitrite in morphine hyperalgesia and tolerance

描述(申请人提供)：阿片类药物如硫酸吗啡是治疗急性和慢性剧烈疼痛的最有效的镇痛剂，但其使用受到对无害和有害刺激的耐受性和过敏性的发展的限制。阿片类药物引起的痛敏和抗伤害性耐受的机制尚不清楚。过氧亚硝酸盐(ONOO-)由超氧化物(O2.-)和一氧化氮(.NO)产生，是一种强烈的促炎和促凋亡活性氮物种，目前与痛觉过敏有关。我们的中心假设是，内源性ONOO-是导致吗啡诱导的痛敏和抗伤害性耐受的一系列信号事件中的近端分子。在小鼠身上，我们发现反复注射吗啡会导致硝基酪氨酸(NT，ONOO-的标志物)的形成。ONOO-的作用被证明是通过联合给予吗啡和NO合成酶的抑制剂、O2的清除剂或新型ONOO-分解催化剂来减少NT的形成和防止抗伤害性耐受。这些与ONOO和抗伤害性耐受有关的关联和因果联系与以下几个方面一致：1)谷氨酸转运体(GLT-1)和谷氨酰胺合成酶(GS)的翻译后硝化；2)促炎细胞因子的形成；以及3)DNA氧化损伤和核因子多聚(ADP-核糖)聚合酶的激活。抑制ONOO-可减弱这些变化。最后，全身应用ONOO分解催化剂的结果通过鞘内给药得到证实，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将确定脊髓ONOO-1与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联系。具体目标2将利用药理学和遗传学方法，确定NADPH氧化酶作为O2的来源的贡献，从而在吗啡过敏和抗伤害耐受的发展过程中从头开始形成ONOO-。具体目标3将阐明ONOO调节痛觉过敏和抗伤害性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，为开发ONOO分解催化剂作为阿片类药物的辅助药物治疗慢性疼痛提供理论基础。项目简介：慢性疼痛影响着大约8600万美国人，每年造成至少1000亿美元的医疗费用和工作效率下降。与公共卫生相关的阿片类药物，如吗啡，是治疗严重慢性疼痛最有效的镇痛剂，但其止痛作用在长期给药过程中往往会减弱，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，恢复了吗啡的止痛作用，开辟了慢性疼痛治疗的新领域，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.