Mechanisms of cAMP signaling that drive spontaneous activity in nociceptors

驱动伤害感受器自发活动的 cAMP 信号传导机制

基本信息

批准号：
10452685
负责人：
Carmen W. Dessauer
金额：
$ 43.1万
依托单位：
UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-08-15 至 2025-07-31
项目状态：
未结题

来源：
https://reporter.nih.gov/project-details/10452685
关键词：
A kinase anchoring protein Action Potentials Acute Address Afferent Neurons Animals Biochemistry C Fiber Cell membrane Cellular biology Chronic Complex Cyclic AMP Cyclic AMP-Dependent Protein Kinases Data Drug Combinations Drug Screening Effectiveness Electrophysiology (science)Exposure to FDA approved Funding Goals Hyperactivity Image Imaging Device In Vitro Injury Joints KRAS2 gene Laboratories Life Link Lipids MAP Kinase Gene Measures Mediating Membrane Lipids Membrane Potentials Microscopy Modeling Neuraxis Neurons Nociceptors Opioid Opioid Receptor Pain Pathway interactions Peripheral Persistent pain Pharmaceutical Preparations Phosphatidylserines Phosphorylation Phosphorylation Site Proteins RAS inhibition Ras/Raf Rattus Reflex action Refractory Resistance Rest Role Signal Transduction Spinal Ganglia Spinal cord injury Spinal cord injury patients Stimulus Testing base cannabinoid receptor chronic pain chronic pain management drug testing endogenous opioids experimental study in vivo in vivo evaluation neurotrophic factor novel painful neuropathy recruit response scaffold severe injury spontaneous pain

项目摘要

Project Summary: Chronic pain caused by injury to the peripheral or central nervous system (neuropathic pain) is notoriously resistant to treatment, while the mechanisms that drive and/or maintain chronic pain remain unclear. We have shown that chronic nociceptor hyperexcitability after severe injury is maintained by cAMP signaling through multiple cAMP effectors, including PKA, EPAC and HCN channels. These pathways are enhanced by AKAP-mediated complex formation with AC and show significant cross-talk with Ras/MAPK signaling. Activation of cAMP- and Ras-mediated pathways initiate at the plasma membrane (PM) and are uniquely sensitive to clustering of lipids within the PM. We have also shown that spinal cord injury reduces AC inhibition by Gαi, resulting in reduced potency of opioids in DRG neurons. This reduced sensitivity can be mimicked in DRG neurons from naïve animals by overnight exposure to neurotrophic factors or by a 5 min, modest depolarization that approaches the firing threshold of DRG neurons after severe injury. Importantly, nociceptor hyperexcitability and reductions in opioid potency, induced by either injury, neurotrophic factors or acute depolarization, can be reversed by inhibition of Ras-dependent signaling or reorganization of lipids in the plasma membrane. We hypothesize that the sustained depolarization that occurs in many injury models drives alterations in PM lipid organization, leading to increased ERK signaling and decreased opioid responses. Release of neurotrophic factors reinforce these pathways and, in conjunction with cAMP signaling, drives nociceptor hyperexcitability and a chronic pain state. To address these hypotheses, we propose three Aims. 1) Determine the mechanism for reduced MOR-Gαi inhibition of AC by C-Raf, 2) Define the mechanism of Ras activation and nociceptor hyperexcitability by depolarization and SCI, and 3) Define functional consequences of interactions among depolarization and cell signaling by cAMP, C-Raf, and ERK. Importantly, our model identifies multiple FDA-approved drugs that could simultaneously enhance endogenous opioid responses and block nociceptor hyperexcitability after severe injury.

项目概要：由周围或中枢神经系统损伤引起的慢性疼痛（神经性疼痛）是众所周知，对治疗有抵抗力，而驱动和/或维持慢性疼痛的机制仍然存在我们已经表明，严重损伤后慢性伤害感受器过度兴奋是通过以下因素维持的。 cAMP 信号传导通过多个 cAMP 效应器，包括 PKA、EPAC 和 HCN 通道。 AKAP 介导的与 AC 形成的复合物增强了通路，并显示出显着的串扰 cAMP 和 Ras 介导的通路的激活在血浆中启动。我们还表明，它对膜（PM）内的脂质聚集特别敏感。脊髓损伤降低了 Gαi 的 AC 抑制，导致 DRG 中阿片类药物的效力降低这种敏感性降低可以在一夜之间在幼稚动物的 DRG 神经元中模仿。暴露于神经营养因子或通过接近放电的 5 分钟适度去极化严重损伤后 DRG 神经元的阈值，伤害感受器过度兴奋和减少。由损伤、神经营养因子或急性去极化引起的阿片类药物效力可以通过抑制 Ras 依赖性信号传导或质膜中脂质的重组来逆转。我们认为许多损伤模型中发生的持续去极化会导致改变 PM 脂质组织中，导致 ERK 信号传导增加和阿片类药物释放减少。神经营养因子与 cAMP 信号传导相结合，强化了这些通路，驱动为了解决这些假设，我们提出了三个假设。目的 1) 确定 C-Raf 减少 MOR-Gαi 对 AC 抑制的机制，2) 定义 Ras 激活和去极化和 SCI 伤害感受器过度兴奋的机制，以及 3) 定义 cAMP、C-Raf 和 cAMP 的去极化和细胞信号传导之间相互作用的功能后果重要的是，我们的模型识别出多种 FDA 批准的药物可以同时增强效果。内源性阿片类药物反应并阻断严重损伤后伤害感受器的过度兴奋。