Cholinergic modulation of Descending Pain Control Pathways

下行疼痛控制通路的胆碱能调节

• 批准号: 10317942
• 负责人: Daniel S McGehee
• 金额: $ 43.87万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-01 至 2023-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10317942
• 关键词: Absence of pain sensation; Acetylcholine; Acute Pain; Address; Adult; Affective; Agonist; American; Analgesics; Anatomy; Biological Assay; Brain; Cell Nucleus; Cells; Cholinergic Receptors; Chronic; Communication; Country; Data; Electrophysiology (science); Face; Fluorescent in Situ Hybridization; Glutamates; Goals; Histologic; Hyperalgesia; Individual; Inflammatory; Infusion procedures; Investigation; Knowledge; Mechanics; Mediating; Modeling; Morphine; Mus; Muscarinics; Naloxone; Neuraxis; Neurons; Neuropathy; Neuropeptides; Neurotransmitters; Nociception; Opioid; Opioid Receptor; Pain; Pain Measurement; Pain management; Pathway interactions; Pedunculopontine Tegmental Nucleus; Pharmaceutical Preparations; Pharmacology; Plague; Public Health; Reproducibility; Role; Signal Transduction; Site; Slice; Source; Synapses; System; Testing; Time; United States; Withdrawal; allodynia; base; cell type; cholinergic; chronic neuropathic pain; chronic pain; chronic painful condition; drug discovery; effective therapy; efficacy testing; experience; experimental study; gamma-Aminobutyric Acid; in vivo; mRNA Expression; midbrain central gray substance; morphine tolerance; nerve injury; non-opioid analgesic; novel; novel therapeutic intervention; opioid epidemic; opioid overdose; opioid use; optical fiber; optogenetics; overdose death; pain model; pain relief; pain signal; painful neuropathy; preference; prescription opioid; receptor; retrograde transport; side effect; spared nerve; statistics; transmission process

Chronic pain conditions plague more than 20% of adults in the United States, emphasizing the need for a more comprehensive understanding of pain control mechanisms and better pain therapies. This need is amplified further by the current opioid crisis, which killed 47,600 Americans in 2018. While opioids are remarkably effective treatments for acute and chronic pain, adverse side effects, including abuse liability and tolerance to the analgesic effects with repeated use, highlight the need for novel non-opioid pain therapies. This need motivates our investigations of pain modulation by acetylcholine (ACh) and its receptors (AChRs) in the ventrolateral periaqueductal gray (vlPAG). Ascending pain signaling from periphery to central nervous system is modulated by the descending pain pathway, including the vlPAG and its projections to rostral ventromedial medulla (RVM) and locus ceruleus (LC). This descending pain pathway is a key site of action of opioids and endogenous pain control. While much is known about this circuitry, the pain modulatory effects of cholinergic inputs to vlPAG are understudied. Our preliminary data show that optogenetic stimulation of cholinergic projections from the pedunculopontine tegmental nucleus (PPTg) to vlPAG is antinociceptive in acute pain. Using cell- and circuit-specific optogenetic approaches, we will test the effect of stimulating cholinergic projections to vlPAG on nociception in a chronic neuropathic pain model, identify the cholinergic receptors mediating these antinociceptive effects, and explore possible interactions between cholinergic signaling and the opioid system. In Aim 1, we will use optogenetic approaches to test antinociceptive effects of stimulating cholinergic PPTg neurons projecting to vlPAG in mice experiencing chronic neuropathic pain. We will also assay affective pain relief of stimulating these projections using a real-time place preference assay. In Aim 2, we will identify cholinergic receptor(s) mediating synaptic communication between PPTg and vlPAG neurons, using high- throughput fluorescence in situ hybridization assay to visualize mRNA expression of muscarinic and nicotinic AChRs on vlPAG neurons. After identifying candidate AChR(s) based on mRNA expression, we will test functional role of these receptors in synaptic communication, using slice electrophysiology and ex vivo optogenetics. Finally, we will test the causal role of identified AChRs in antinociception in vivo using optogenetics and pharmacology in neuropathic pain assays. In Aim 3, we will explore possible interactions between these cholinergic mechanisms and the opioid system, by testing the efficacy of cholinergic analgesia in morphine-tolerant mice and during naloxone precipitated withdrawal from chronic morphine treatment. These studies will employ histological, electrophysiological, optogenetic and pharmacological approaches to advance our knowledge of cholinergic modulation of descending pain pathways, to ultimately help identify novel opioid-independent targets for treating chronic pain.

慢性疼痛困扰着超过 20% 的美国成年人，强调需要采取更多措施 全面了解疼痛控制机制和更好的疼痛治疗。这种需求被放大 当前的阿片类药物危机进一步加剧了这一危机，2018 年导致 47,600 名美国人死亡。 有效治疗急性和慢性疼痛、不良副作用，包括滥用倾向和耐受性 重复使用的镇痛作用凸显了对新型非阿片类疼痛疗法的需求。这个需要 激发了我们对乙酰胆碱（ACh）及其受体（AChR）在疼痛调节方面的研究 腹外侧导水管周围灰质（vlPAG）。从外周到中枢神经系统的上行疼痛信号 受下行疼痛通路调节，包括 vlPAG 及其对头侧腹内侧的投射 髓质 (RVM) 和蓝斑 (LC)。这种下行疼痛通路是阿片类药物的关键作用部位， 内源性疼痛控制。虽然人们对这种电路了解很多，但胆碱能的疼痛调节作用 vlPAG 的输入尚未得到充分研究。我们的初步数据表明，胆碱能的光遗传学刺激 从脚桥被盖核 (PPTg) 到 vlPAG 的投射在急性疼痛中具有镇痛作用。 使用细胞和电路特异性光遗传学方法，我们将测试刺激胆碱能的效果 对慢性神经病理性疼痛模型中伤害感受的 vlPAG 进行预测，识别胆碱能受体 介导这些抗伤害作用，并探索胆碱能信号传导和 阿片类药物系统。 在目标 1 中，我们将使用光遗传学方法来测试刺激胆碱能的抗伤害作用 在经历慢性神经性疼痛的小鼠中，PPTg 神经元投射到 vlPAG。我们还将分析情感 使用实时位置偏好分析刺激这些投射可以缓解疼痛。在目标 2 中，我们将确定 胆碱能受体介导 PPTg 和 vlPAG 神经元之间的突触通讯，使用高 通过荧光原位杂交测定毒蕈碱和烟碱的 mRNA 表达可视化 vlPAG 神经元上的 AChR。根据 mRNA 表达确定候选 AChR 后，我们将测试 使用切片电生理学和离体研究这些受体在突触通讯中的功能作用 光遗传学。最后，我们将使用以下方法测试已识别的 AChR 在体内抗伤害作用中的因果作用： 神经病理性疼痛测定中的光遗传学和药理学。在目标 3 中，我们将探索可能的相互作用 通过测试胆碱能镇痛的功效，研究这些胆碱能机制和阿片类药物系统之间的关系 在吗啡耐受的小鼠中和在纳洛酮期间加速了长期吗啡治疗的戒断。 这些研究将采用组织学、电生理学、光遗传学和药理学方法来 增进我们对下行疼痛通路的胆碱能调节的了解，最终帮助识别 用于治疗慢性疼痛的新的不依赖阿片类药物的靶标。