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: 8101252
• 负责人: Ryan Joseph Horvath
• 金额: $ 4.68万
• 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/8101252
• 关键词: Acute; Adult; Adverse effects; Affect; Agonist; Analgesics; Attenuated; Binding; Biological Assay; Cations; Cell Culture Techniques; Cell Migration Induction; Cells; Chemotaxis; Chronic; Development; Diabetic Neuropathies; Dose; Effectiveness; Emotional; Goals; HIV; Headache; Immune; Immunofluorescence Immunologic; Immunology; In Vitro; Investigation; Life; Ligands; Low Back Pain; Lumbar spinal cord structure; Maintenance; Mediating; Microglia; Morphine; Neonatal; Neuraxis; Neuroglia; Nociception; Opioid; Opioid Receptor; P2X-receptor; Pain; Pain Disorder; Patients; Play; Posterior Horn Cells; Postherpetic neuralgia; Purinoceptor; Rattus; Receptor Activation; Receptor Inhibition; Research; Reverse Transcriptase Polymerase Chain Reaction; Role; Spinal; Spinal Cord; Spinal Cord Diseases; Syndrome; Therapeutic; Time; Western Blotting; cell motility; chronic neuropathic pain; chronic pain; cytokine; dorsal horn; drug discovery; extracellular; in vivo; inhibitor/antagonist; mRNA Expression; migration; mu opioid receptors; nerve injury; new therapeutic target; novel; oncology; pain behavior; painful neuropathy; patient population; physical conditioning; 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且令人衰弱的疾病，影响着美国超过 500 万人，极大地影响了患者的情绪和身体健康。阿片类药物在治疗慢性疼痛方面效果有限，并且受到耐受性发展的限制。该提案旨在阐明阿片类药物耐受的新机制，并提供新的治疗目标，这可能有可能帮助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，已被证明在慢性疼痛和阿片类药物耐受中发挥着重要作用。同样，由 ATP/ADP 激活的 P2X 受体已被证明可以介导急性伤害感受和慢性疼痛状态。我们建议通过以下假设的研究来研究小胶质细胞在吗啡耐受中的作用：吗啡结合小胶质细胞μ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，诱导背角神经元敏化和耐受性形成。我们将通过完成以下具体目标来研究这一假设：1）研究μ阿片类药物介导的P2X4受体表达增强和小胶质细胞激活对体外细胞迁移的影响；2）检查体内P2X4受体激活与吗啡耐受之间的关系。为了研究这些具体目标，我们将采用原代小胶质细胞培养物和成年大鼠。具体目标1将通过体外研究μ阿片类激动剂、拮抗剂和P2X4受体拮抗剂对小胶质细胞迁移的影响来完成。在一组单独的实验中，我们将评估吗啡是否诱导小胶质细胞增加 P2X4 受体表达。具体目标2将通过体内研究P2X4受体拮抗剂对吗啡耐受性和神经胶质细胞激活的发展和维持的影响来完成。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。可以研究这种相互作用，以进一步了解为什么吗啡等阿片类药物在缓解某些患者群体的疼痛方面无效，而在其他患者群体中随着时间的推移疗效逐渐减弱。这项研究的目标是为新疗法提供靶点，这些新疗法不具有与现有阿片类药物相同的耐受形成倾向和相似的副作用。