Mechanistic Study of Pain Inhibition by Activation of Non-nociceptive Afferent Fibers

非伤害性传入纤维激活抑制疼痛的机制研究

• 批准号: 10112977
• 负责人: Yun Guan
• 金额: $ 48.76万
• 依托单位: JOHNS HOPKINS UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-03-01 至 2024-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10112977
• 关键词: Adenosine; Adjuvant; Adverse effects; Affect; Agonist; Amyloid beta-Protein; Animal Model; Anti-Inflammatory Agents; Astrocytes; Attenuated; Behavior; Biological; Biological Process; C Fiber; Chemosensitization; Clinical; Clinical Trials; Dose; Dose-Limiting; Drug Targeting; Electric Stimulation; Electric Stimulation Therapy; Electrophysiology (science); Etiology; Fiber; Floods; Frequencies; Future; Genetic; Goals; Heterogeneity; Homeostasis; Human; Image; Inflammation Mediators; Inflammatory; Interneurons; Link; Microglia; Nerve Fibers; Neuroglia; Neurons; Nociception; Opioid; Pain; Pathogenesis; Pharmaceutical Preparations; Pharmacology; Pharmacotherapy; Physiological; Play; Posterior Horn Cells; Process; Rattus; Receptor Activation; Refractory; Research Personnel; Role; Signal Transduction; Slice; Specificity; Spinal; Spinal Cord; System; Testing; chronic pain; cost; dorsal column; dorsal horn; excitatory neuron; gamma-Aminobutyric Acid; human study; improved; in vivo; nerve injury; neurochemistry; novel; optogenetics; pain inhibition; painful neuropathy; patch clamp; receptor; reuptake; side effect; tool; translational study; transmission process

PROJECT SUMMARY Electrical stimulation (ES) of low-threshold Aβ-nerve fibers is a clinical strategy for treating chronic pain that is refractory to pharmacotherapies, including opiates. However, the mechanisms underlying pain inhibition by Aβ-fiber activation remain elusive, limiting further clinical and technological improvements. Our major goal is to uncover spinal neuronal and non-neuronal mechanisms of pain inhibition by Aβ-ES, and to identify targets for rationally selecting adjuvant drugs to enhance pain inhibition and avoid side effects. In Aim 1, by using animal models of neuropathic pain, we will first delineate spinal neuronal mechanisms by which Aβ-ES inhibits pain transmission. Electrophysiology studies will uncover how different forms of Aβ-ES modulate functionally distinct subsets of superficial dorsal horn neurons (e.g., inhibitory vs. excitatory neurons), and further differentiate the underlying receptor mechanisms. We postulate that the excitatory neuron-preferred inhibition may enable Aβ-ES to be used together with low-dose adjuvant drugs for circuitry-specific enhancement of pain inhibition. We will test whether limiting endogenous adenosine degradation or GABA reuptake during Aβ-ES specifically enhances the inhibition of dorsal horn excitatory and projection neurons and increases the net inhibition of pain transmission. In Aim 2, we will then unveil a non-neuronal pain gating mechanism activated by Aβ-ES. By conducting high-throughput GCaMP6 imaging and electrophysiology recording, we will examine whether Aβ-ES activates spinal astrocytes to induce inhibition of spinal nociceptive transmission, and whether this process is attenuated by nerve injury. Since pain inhibition by dorsal column stimulation (DCS) is intrinsically linked with activation of Aβ-fibers, DCS will be used as a proof-of-principle for studying Aβ-ES in vivo. We will examine whether DCS changes astrocyte reactive markers, affects the levels of pro-inflammatory mediators, and promotes microglial polarization from M1 to M2 state after nerve injury. We will further test whether glia-derived adenosine inhibits excitatory or projection neurons and enhances Aβ-ES–induced inhibition of these neurons. Our findings in Aims 1 and 2 will help us to develop new strategies of enhancing pain inhibition by Aβ-ES in Aim 3. We will test whether inhibition of neuropathic pain-related behavior by DCS can be enhanced by limiting degradation of endogenous adenosine and inhibiting GABA reuptake in the spinal cord. Owing to use-dependent and circuitry-specific features, we expect that the treatment will not induce side effects. Our findings will reveal new mechanisms underlying pain inhibition by Aβ-ES, and will provide important rationales and drug targets for future translational studies aimed at using low-dose adjuvant drugs to improve the efficacy and specificity of pain inhibition by Aβ-ES therapies.

项目总结 电刺激低阈值Aβ神经纤维是治疗慢性疼痛的一种临床策略 这对包括阿片类药物在内的药物治疗是难以奏效的。然而，疼痛背后的机制 Aβ纤维激活的抑制作用仍然难以捉摸，限制了进一步的临床和技术进步。我们的 主要目的是揭示β-ES抑制疼痛的脊髓神经元和非神经元机制，并 确定合理选择辅助药物的靶点，以增强疼痛抑制作用，避免副作用。在AIM 通过使用神经病理性疼痛的动物模型，我们将首先描述脊髓神经元的机制，通过这些机制 β-ES可以抑制疼痛的传递。电生理学研究将揭示不同形式的β-ES 调制功能不同的浅层背角神经元亚群(例如，抑制性与兴奋性 神经元)，并进一步区分潜在的受体机制。我们假设这种兴奋性 神经元优先抑制可能使Aβ-ES与小剂量佐剂药物联合使用 特定于电路的疼痛抑制增强。我们将测试限制内源性腺苷 β-ES中降解或重新摄取GABA可特异性增强对背角兴奋性的抑制 并投射神经元，增加疼痛传递的净抑制。在《目标2》中，我们将推出一款 Aβ-ES激活的非神经元痛门机制。通过进行高通量GCaMP6成像 和电生理记录，我们将检测Aβ-ES是否激活脊髓星形胶质细胞诱导 脊髓伤害性信息传递的抑制，以及这一过程是否因神经损伤而减弱。自.以来 背柱刺激对疼痛的抑制与Aβ纤维的激活有内在联系，背柱刺激将 可作为体内研究β-ES的验证原则。我们将检查DCs是否改变星形胶质细胞 反应性标志物，影响促炎介质水平，并促进小胶质细胞极化。 神经损伤后由M1状态转为M2状态。我们将进一步测试胶质细胞来源的腺苷是否抑制兴奋性或 投射神经元并增强Aβ-ES对这些神经元的抑制作用。我们在AIMS 1和2中的发现 将帮助我们在AIM 3中开发通过Aβ-ES增强疼痛抑制的新策略。我们将测试 通过限制DCs的降解，可以加强对神经病理性疼痛相关行为的抑制 内源性腺苷和抑制脊髓内GABA的再摄取。由于依赖于使用和 电路特有的特点，我们预计治疗不会引起副作用。我们的发现将揭示 β-ES抑制疼痛的新机制，并将提供重要的理论基础和药物靶点 对于未来旨在使用低剂量辅助药物来提高疗效和特异性的转译研究 Aβ-ES疗法的疼痛抑制作用。