Descending facilitation of pain by mu-opioid receptor-expressing neurons in the rostral ventromedial medulla

延髓头端腹内侧表达μ阿片受体的神经元对疼痛的下降促进作用

• 批准号: 10268171
• 负责人: RUBY HOLLAND
• 金额: $ 5.18万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-01 至 2023-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10268171
• 关键词: Absence of pain sensation; Acute; Acute Pain; Adverse effects; Anatomy; Anesthesiology; Attenuated; Avidin; Behavior; Behavioral; Behavioral Assay; Behavioral Paradigm; Brain Stem; Capsaicin; Cells; Chemicals; Clinical; Confocal Microscopy; Dependovirus; Development; Electric Stimulation; Electrophysiology (science); Exhibits; Fellowship; Fluorescent Probes; Fluorescent in Situ Hybridization; Fluoro-Gold; Genetic; Genetic Techniques; Glutamates; Goals; Hyperalgesia; Immunohistochemistry; In Situ Hybridization; In Vitro; Interneurons; Knock-in Mouse; Knowledge; Light; Measures; Mechanics; Mediating; Modeling; Molecular; Morphine; Morphology; Mus; Neuraxis; Neurons; Neurosciences; Nociception; Opioid; Opioid agonist; Pain; Pain Measurement; Pathway interactions; Patients; Pattern; Persistent pain; Persons; Pharmacology; Phenotype; Physicians; Physiology; Play; Positioning Attribute; Preparation; Quality of life; Reflex action; Role; Scientist; Site; Slice; Specialist; Spinal; Spinal Cord; Stains; Stimulus; Synapses; Testing; Therapeutic; Time; Tracer; Training; Viral; Work; base; cell type; chronic neuropathic pain; chronic pain; dorsal horn; experimental study; improved; in vivo; inflammatory pain; interest; islet; mu opioid receptors; nerve injury; neural circuit; neurobiotin; neurochemistry; novel; optogenetics; pain behavior; pain inhibition; pain signal; relating to nervous system; response; skills; spared nerve; success; tool

Project Summary/Abstract Pain is a debilitating and prevalent condition which severely impacts quality of life. Unfortunately, our current treatment options are limited by adverse effects, and the pathways modulating pain signaling are not fully understood. The rostral ventromedial medulla (RVM) is a brainstem site which plays a critical role in pain modulation, primarily by sending descending projections to the spinal cord. While non-specific electrical stimulation of the RVM produces analgesia, RVM neurons can either facilitate or inhibit pain. RVM spinal projections can be characterized as ON-cells, OFF-cells, or NEUTRAL-cells based on their response to, and effect on, nocifensive reflexes, but many details remain unclear. Morphine acts at the mu-opioid receptor (MOR) to inhibit neuronal activity and produces analgesia in part by activating OFF-cells and inhibiting ON-cells. Thus, it follows that ON-cells express MOR. Numerous studies support the assertion that ON-cell circuitry is implicated in chronic pain and opioid-induced hyperalgesia. However, until recently we lacked the genetic tools necessary to dissect the circuitry of MOR-expressing neurons, including ON-cells, in the RVM. With the recent development of the Oprm1-Cre knock-in mouse, we now have the genetic tool necessary to study these circuits in better detail. The goal of this proposal is to therefore test the hypothesis that MOR+ RVM neurons facilitate pain by inhibiting interneurons in the superficial dorsal horn. I will test this hypothesis using a combination of genetic, molecular, electrophysiological, and behavioral approaches. Aim 1 will investigate which cell types in the RVM express MOR through viral tracing, fluorescent in situ hybridization (FISH), and immunohistochemistry (IHC). Aim 2A will identify the MOR+ RVM inputs received by interneurons in the dorsal horn through optogenetics and slice electrophysiology. Aim 2B will explore the electrophysiological, neurochemical, and morphological phenotype of dorsal horn interneurons receiving input from MOR+ RVM neurons using a combined electrophysiology and anatomical approach. Aim 3 will test the hypothesis that MOR+ RVM neurons facilitate mechanical, chemical, and thermal pain through the use of chemogenetics and behavioral assays of acute and chronic neuropathic pain. The work detailed in this proposal is critically important because an enhanced understanding of the circuitry underlying the RVM can pave the way for the development of novel pain therapeutics and will advance the field of neuroscience. Furthermore, this proposal is heavily inspired by my clinical interest in anesthesiology, where I plan to work as a pain specialist and investigate pain signaling mechanisms to minimize patient suffering and improve quality of life. The professional, technical, and intellectual skills which will be developed over the course of this fellowship will position me for success as a physician-scientist in academic anesthesiology.

项目摘要/摘要 疼痛是一种严重影响生活质量的衰弱和普遍的疾病。不幸的是，我们目前 治疗方案受到不良反应的限制，调节疼痛信号的通路也不完全。 明白了。延髓头端腹内侧(RVM)是脑干部位，在疼痛中起关键作用。 调制，主要通过向脊髓发送下行投射。而非特定的电气 刺激RVM产生镇痛作用，RVM神经元既可以促进疼痛，也可以抑制疼痛。RVM脊髓 投射可以被表征为开细胞、离细胞或中性细胞，基于它们对 对无提示反射的影响，但许多细节仍不清楚。吗啡作用于单位阿片受体(MOR) 抑制神经元活动，部分通过激活离细胞和抑制开细胞而产生镇痛作用。因此， 由此可见，ON细胞表达MOR。大量研究支持这样一种断言，即细胞上的电路与之有关 治疗慢性疼痛和阿片类药物引起的痛觉过敏。然而，直到最近，我们还缺乏必要的基因工具 解剖RVM中包括ON细胞在内的MOR表达神经元的电路。随着最近的发展 对于OPRM1-CRE敲入小鼠，我们现在有了必要的遗传工具来更详细地研究这些电路。 因此，这项提议的目标是检验MOR+RVM神经元通过抑制疼痛而促进疼痛的假设 浅层背角内的中间神经元。我将使用遗传、分子、 电生理学和行为学方法。目标1将调查RVM Express中的哪些细胞类型 通过病毒示踪、荧光原位杂交(FISH)和免疫组织化学(IHC)检测MOR。目标2 A将 通过光遗传学和切片识别背角中间神经元接受的MOR+RVm传入 电生理学。目的2B将探索电生理、神经化学和形态表型 电生理学和电生理学相结合的方法研究接受MOR+RVM神经元输入的背角中间神经元 解剖学方法。目的3将检验MOR+RVM神经元促进机械，化学， 和热痛通过使用化学遗传学和行为分析的急性和慢性神经病 疼痛。本建议书中详细介绍的工作至关重要，因为提高了对电路的了解 RVM的基础可以为新的疼痛疗法的发展铺平道路，并将推动该领域的发展 神经科学的研究。 此外，这个提议的灵感主要来自于我对麻醉学的临床兴趣，我计划在那里工作 疼痛专家和研究疼痛信号机制，以最大限度地减少患者痛苦并提高治疗质量 生活。在此奖学金的过程中将发展的专业、技术和智力技能 将使我在麻醉学学术领域成为一名成功的内科科学家。