PPAR Inhibition of Spinal Pain Transmission

项目说明 过氧化物酶体增殖物激活受体-γ(PPAR？)是PPAR的重要靶点 噻唑二酮(TZD)类抗糖尿病药物。我们的初步结果描述了PPAR的存在 背角中的mRNA和蛋白质。此外，我们还证明了机械和热 鞘内给药可迅速减轻与炎症或神经损伤相关的过敏反应 罗格列酮(一种TZD)和15d-PGJ2(一种内源性PPAR配体)的剂量和PPAR依赖关系 方式，并通过系统地给予吡格列酮，一种BBB的意思，FDA批准的配体。中环 这一设想的假设是，背角PPAR？的配体依赖的激活减少了损伤- 诱导脊髓神经元和神经胶质细胞的激活，然后抑制炎症和 神经性疼痛。本申请的目的是确定PPAR的潜在机制-- 介导抑制炎症性或神经病理性疼痛，重点是吡格列酮。我们的长期目标是 研究计划是利用PPAR信号的治疗潜力来缓解人类的慢性疼痛。 目的1验证PPAR激动剂可减少痛觉过敏和痛觉过敏的假说。我们将使用 药理药物和神经系统特异性PPAR？缺失突变体的作用 脊髓中的PPAR？信号传导到慢性疼痛的诱导和维持。首先，我们将确定 无论是单次鞘内注射还是全身应用吡格列酮和15d-PGJ2均可减少 炎症性和神经性疼痛。我们预测它们的止痛作用将被PPAR？阻断 对抗者。其次，我们将确定慢性鞘内或口服PPAR激动剂， 在组织或神经损伤之前或之后开始，减少炎症和神经病理性疼痛的行为迹象。 第三，我们预测，在神经元特异性PPAR基因敲除的小鼠中，不会发生抗痛觉异常的作用。 目的2将验证PPAR配体减少损伤诱导的神经元激活和 背角内的小胶质细胞。创伤大鼠躯体感觉刺激诱导血管内皮生长因子的表达 即刻早期基因c-fos，位于背角浅层。我们预测鞘内 吡格列酮可减少炎症和神经损伤诱导的Fos免疫反应神经元的表达，AS 以及小胶质细胞活化的标志物OX-42的表达。 目的3将检验内源性PPAR系统强直抑制痛觉过敏的假说。首先，我们将 确定PPAR是否在疼痛时被激活的神经元和/或神经胶质细胞中表达。第二，在一个 延伸AIMS 1-2，我们将确定受体拮抗剂和基因缺失是否会增加痛觉过敏 以及神经元/神经胶质细胞的激活。如果是肯定的，那么我们将确定PPAR？信令元素是否共同- 因痛觉异常而不同。在神经损伤或持续性炎症后的不同时间，我们将评估：行为 和C)15d-PGJ2水平的LC/MS/MS分析。

PROJECT DESCRIPTION Peroxisome proliferator-activated receptor gamma (PPAR ¿) is well-characterized as a key target of the thiazolinedione (TZD) class of anti-diabetic drugs. Our preliminary results describe the existence of PPAR ¿ mRNA and protein in the dorsal horn. Furthermore, we demonstrate that the mechanical and thermal hypersensitivity associated with inflammation or nerve injury was rapidly reduced by intrathecal administration of rosiglitazone (a TZD) and 15d-PGJ2 (an endogenous PPAR ¿ ligand) in a dose- and PPAR ¿-dependent manner, and by systemic administration of pioglitazone, a BBB-permeant, FDA-approved ligand. The central hypothesis of this proposal is that ligand-dependent activation of PPAR¿ in the dorsal horn decreases injury- induced activation of spinal neurons and glia that then dampens behavioral signs of inflammatory and neuropathic pain. The objective of the present application is to identify the mechanisms underlying PPAR- mediated inhibition of inflammatory or neuropathic pain, with a focus on pioglitazone. The long-term goal of our research program is to harness the therapeutic potential of PPAR signaling to alleviate chronic pain in humans. AIM 1 will test the hypothesis that PPAR ¿ agonists reduce allodynia and hyperalgesia. We will use pharmacological agents and nervous system-specific PPAR ¿ deletion mutants to determine the contribution of PPAR ¿ signaling in the spinal cord to the induction and maintenance of chronic pain. First, we will determine whether single intrathecal or systemic administration of pioglitazone and 15d-PGJ2 reduces behavioral signs of inflammatory and neuropathic pain. We predict that their analgesic actions will be blocked with PPAR ¿ antagonists. Second, we will determine whether chronic intrathecal or oral administration of PPAR ¿ agonists, begun before or after tissue or nerve injury, reduces behavioral signs of inflammatory and neuropathic pain. Third, we predict that anti-allodynic actions will not occur in mice with neuron-specific PPAR ¿ knockdown. AIM 2 will test the hypothesis that PPAR ¿ ligands reduce injury-induced activation of neurons and microglia in the dorsal horn. Somatosensory stimulation of injured rats induces the expression of the immediate early gene, c-fos, in the superficial laminae of the dorsal horn. We predict that intrathecal pioglitazone will reduce inflammation- and nerve injury-induced expression of Fos immunoreactive neurons, as well as the expression of OX-42, a marker of microglia activation. AIM 3 will test the hypothesis that endogenous PPAR ¿ systems tonically inhibit allodynia. First, we will determine if PPAR¿ expression occurs in neurons and/or glia that are activated during pain. Second, in an extension of Aims 1-2, we will determine whether receptor antagonists and genetic deletion increase allodynia and neuronal/glial activation. If affirmative, then we will determine whether the PPAR¿ signaling elements co- vary with allodynia. At various times after nerve injury or persistent inflammation, we will evaluate: behavior and A) PPAR ¿ mRNA and protein; B) phosphorylated PPAR ¿; and C) 15d-PGJ2 levels with LC/MS/MS.