Morphine Induced P2X4 Receptor Expression: Implications for Opioid Tolerance

吗啡诱导的 P2X4 受体表达：对阿片类药物耐受性的影响

• 批准号: 7485431
• 负责人: Ryan Joseph Horvath
• 金额: $ 4.6万
• 依托单位: DARTMOUTH COLLEGE
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7485431
• 关键词: Acute; Adult; Adverse effects; Affect; Agonist; Analgesics; Attenuated; Behavior; Binding; Biological Assay; Cations; Cell Migration Induction; Cells; Chemotaxis; Chronic; Condition; Development; Diabetic Neuropathies; Dose; Effectiveness; Emotional; Goals; HIV; Headache; Health; Immune; Immunofluorescence Immunologic; Immunology; In Vitro; Investigation; Life; Ligands; Low Back Pain; Lumbar spinal cord structure; Maintenance; Mediating; Messenger RNA; Microglia; Morphine; Neonatal; Neuraxis; Neuroglia; Nociception; Opioid; Opioid Receptor; P2X-receptor; Pain; Pain Disorder; Patients; Play; Population; Posterior Horn Cells; Postherpetic neuralgia; Purinoceptor; Range; Rattus; Receptor Activation; Receptor Inhibition; Research; Reverse Transcriptase Polymerase Chain Reaction; Role; Spinal; Spinal Cord; Spinal Cord Diseases; Syndrome; Therapeutic; Thinking; Time; Western Blotting; cell motility; chronic neuropathic pain; chronic pain; cytokine; dorsal horn; drug discovery; extracellular; in vivo; inhibitor/antagonist; migration; mu opioid receptors; nerve injury; novel; novel therapeutics; oncology; painful neuropathy; prevent; protein expression; receptor; receptor expression; research study; success

DESCRIPTION (provided by applicant): Chronic neuropathic pain is a common and debilitating ailment affecting more than 5 million people in the US, that dramatically affects the emotional and physical health of patients suffering from it. Opioids have only marginal success in treating chronic pain conditions and are limited by the development of tolerance. This proposal seeks to elucidate a novel mechanism of opioid tolerance and provide a new target for therapy, which could have the potential of aiding a large, underserved patient population. Microglia, the resident immune cell of the CNS have been shown to play an important role in both chronic pain and opioid tolerance. Similarly P2X receptors, which are activated by ATP/ADP, have been shown to mediate acute nociception and chronic pain states. We propose to study the role of microglial cells in morphine tolerance through the investigation of the following hypothesis: Morphine binds microglial mu opioid receptors, enhancing expression of P2X4 receptors, activating them and inducing cell migration. This activation and induction of cell migration leads to locally elevated cytokines and diffusible proinflammatory factors, inducing dorsal horn neuron sensitization and tolerance formation. We will investigate this hypothesis through the completion of the following Specific Aims: 1) Investigate the effect of mu opioid mediated enhancement of P2X4 receptor expression and microglial activation on cell migration in vitro and 2) Examine the relationship between P2X4 receptor activation and morphine tolerance in vivo. To investigate these Specific Aims, we will employ primary microglial cell culture and adult rats. Specific Aim 1 will be completed through the in vitro study of the effects of mu opioid agonists, antagonists and antagonists to P2X4 receptors on microglial migration. In a separate set of experiments, we will evaluate whether morphine induces microglial cells to increase P2X4 receptor expression. Specific Aim 2 will be completed through the in vivo study of the effects of P2X4 receptor antagonists on the development and maintenance of morphine tolerance and glial activation. The study of the effect of morphine on P2X4 receptor expression and activation has the potential to uncover a new mechanism of morphine tolerance. This interaction can be investigated to further understand why opioids such as morphine are ineffective in relieving pain in some patient populations and loose effectiveness over time in others. The goal of this research is to provide targets for new therapeutics that do not share the same propensity for tolerance formation and similar side effects as current opioids.

描述（由申请人提供）：慢性神经性疼痛是一种常见的使人衰弱的疾病，影响着美国500多万人，严重影响着患者的情绪和身体健康。阿片类药物在治疗慢性疼痛方面只有边际成功，并且受到耐受性发展的限制。该建议旨在阐明阿片类药物耐受性的新机制，并提供新的治疗靶点，这可能有助于大量服务不足的患者群体。小胶质细胞是中枢神经系统的常驻免疫细胞，在慢性疼痛和阿片类药物耐受中发挥重要作用。同样，P2X受体被ATP/ADP激活，已被证明介导急性伤害感觉和慢性疼痛状态。我们建议通过以下假设来研究小胶质细胞在吗啡耐受中的作用：吗啡结合小胶质mu阿片受体，增强P2X4受体的表达，激活它们并诱导细胞迁移。这种细胞迁移的激活和诱导导致局部细胞因子和扩散性促炎因子升高，诱导背角神经元致敏和耐受性形成。我们将通过完成以下具体目的来验证这一假设：1)在体外研究mu阿片介导的P2X4受体表达增强和小胶质细胞活化对细胞迁移的影响；2)在体内研究P2X4受体活化与吗啡耐受的关系。为了研究这些特异性目的，我们将采用原代小胶质细胞培养和成年大鼠。特异性Aim 1将通过体外研究mu阿片受体激动剂、拮抗剂和P2X4受体拮抗剂对小胶质细胞迁移的影响来完成。在另一组实验中，我们将评估吗啡是否诱导小胶质细胞增加P2X4受体的表达。特异性Aim 2将通过体内研究P2X4受体拮抗剂对吗啡耐受性的发展和维持以及神经胶质活化的影响来完成。研究吗啡对P2X4受体表达和激活的影响，有可能揭示吗啡耐受的新机制。这种相互作用可以进一步研究，以进一步理解为什么阿片类药物如吗啡在缓解一些患者群体的疼痛方面无效，而在另一些患者群体中随着时间的推移效果不佳。这项研究的目的是为新疗法提供靶点，这些疗法不具有与当前阿片类药物相同的耐受性形成倾向和类似的副作用。