Mechanisms in nociceptors driving ongoing activity and ongoing pain.

伤害感受器驱动持续活动和持续疼痛的机制。

基本信息

批准号：
9761212
负责人：
Elia Rose Lopez
金额：
$ 3.25万
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：
2019
资助国家：
美国
起止时间：
2019-06-01 至 2021-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9761212
关键词：
A kinase anchoring protein Action Potentials Acute Afferent Neurons Algorithmic Analysis Automobile Driving Blood Platelets Cells Chemosensitization Conflict (Psychology)Coupled Cyclic AMP-Dependent Protein Kinases Data Dose G-Protein-Coupled Receptors Gated Ion Channel Generations Incidence Inflammation Mediators Injury Intervention Ion Channel Ion Channel Gating Ligands Maintenance Mechanics Mediating Membrane Potentials Microscopy Modeling Molecular Neurons Nociception Nociceptors PKA inhibitor Pain Pathway interactions Patients Peripheral Persistent pain Pharmacology Play Postoperative Pain Production Rattus Receptor Signaling Rest Role Serotonin Signal Pathway Signal Transduction Site Spinal cord injury Stimulus Surgical incisions Techniques Testing Tissues Work base care costs chronic pain defined contribution improved insight ion channel blocker novel pain behavior pain model painful neuropathy patch clamp postoperative recovery preference receptor scaffold serotonin receptor spontaneous pain tool voltage wound

项目摘要

Project Summary Management of ongoing pain not only improves patient comfort but also accelerates postoperative recovery and diminishes the likelihood of developing chronic pain, ultimately reducing the cost of care. Many types of pain at rest (spontaneous or ongoing pain) are likely driven by ongoing activity (OA) in nociceptors that occurs in the absence of a discrete stimulus. In a model of neuropathic pain, nociceptive OA is produced by a prolonged depolarization of resting membrane potential, reduction of the action potential threshold, and an increased incidence of large depolarizing spontaneous fluctuations (DSFs) of the membrane potential. A low dose of the inflammatory mediator serotonin (5-HT), when combined with artificial depolarization, strongly potentiates the generation of large DSFs and OA in probable nociceptors from uninjured rats, showing that DSFs can also be enhanced acutely to promote OA. A variety of 5-HT receptors are expressed in sensory neurons, and it is unknown which of these receptor types and downstream pathways are important for 5-HT potentiation of DSFs. Previous studies demonstrate that AKAP-scaffolded PKA activity is important for maintenance of OA in nociceptors after spinal cord injury. The T-type voltage-gated Ca2+ channel Cav3.2 is stimulated by PKA and by Gs-coupled 5HT7 receptor activity, and PKA-dependent internalization of Slack KNa channels induces nociceptor hyperexcitability. These and other observations led to the hypothesis that peripheral 5-HT modulates specific Ca2+ (T-type), and K+ (KNa) conductances via PKA to generate large DSFs that promote OA in nociceptors and ultimately ongoing pain. This hypothesis will be tested in three specific aims. In Aim 1, we will determine the receptors and cell signaling mechanisms mediating 5-HT potentiation of DSFs and OA. Using available pharmacological tools along with patch clamp and high content microscopy techniques, we will test the hypothesis that 5-HT enhancement of DSFs is mediated largely by PKA activation downstream of Gs-coupled 5- HT receptors. In Aim 2, the specific conductances important for 5-HT-dependent generation of large DSFs and OA will be defined. Using patch clamp recording and pharmacology, we will probe the necessity and sufficiency of increased T-type Ca2+ and TRPC channel conductances and inhibition of KNa channel conductance for generation of large DSFs. Our mechanistic model for enhancement of the generation of large DSFs and OA may be particularly relevant to deep tissue incision pain in which platelet aggregates release 5-HT at and near a wound. Deep tissue incision has been shown to induce both OA in nociceptors and spontaneous pain behavior for a few days after injury. It is unknown whether 5-HT or PKA at or near the incision site plays a role in the OA and ongoing pain following incision. In Aim 3, we will determine whether peripheral 5-HT and PKA contribute to pain behavior in a model of postoperative pain. This proposed study will contribute new insight into the molecular mechanisms underlying pain-related ongoing activity in nociceptors and the contributions of peripheral serotonin and PKA to ongoing and evoked pain in a postoperative pain model.

项目概要持续疼痛的管理不仅可以提高患者的舒适度，还可以加速术后恢复和减少发生慢性疼痛的可能性，最终降低护理成本。许多类型的疼痛休息（自发性或持续性疼痛）可能是由发生在疼痛感受器中的持续活动（OA）驱动的缺乏离散刺激。在神经性疼痛模型中，伤害性 OA 是由长时间的疼痛产生的。静息膜电位去极化、动作电位阈值降低、动作电位阈值增加膜电位大的去极化自发波动（DSF）的发生率。低剂量的炎症介质血清素 (5-HT) 与人工去极化相结合，可强烈增强在未受伤大鼠的可能伤害感受器中产生大量 DSF 和 OA，表明 DSF 也可以急剧增强以促进 OA。感觉神经元中表达多种5-HT受体，目前尚不清楚这些受体类型和下游途径中哪些对于 DSF 的 5-HT 增强作用很重要。先前的研究表明 AKAP 支架 PKA 活性对于维持 OA 很重要脊髓损伤后的伤害感受器。 T 型电压门控 Ca2+ 通道 Cav3.2 受 PKA 和 Gs 偶联 5HT7 受体活性和 Slack KNa 通道的 PKA 依赖性内化诱导伤害感受器过度兴奋。这些和其他观察结果得出这样的假设：外周 5-HT 调节特定的 Ca2+（T 型）和 K+（KNa）通过 PKA 电导产生大的 DSF，促进伤害感受器中的 OA 以及最终持续的痛苦。该假设将在三个具体目标上进行检验。在目标 1 中，我们将确定介导 DSF 和 OA 5-HT 增强的受体和细胞信号传导机制。使用可用药理学工具以及膜片钳和高内涵显微镜技术，我们将测试假设 DSF 的 5-HT 增强主要是由 Gs 偶联 5-HT 下游的 PKA 激活介导的 HT受体。在目标 2 中，比电导对于 5-HT 依赖性大 DSF 的生成很重要， OA将被定义。利用膜片钳记录和药理学，我们将探讨其必要性和充分性增加 T 型 Ca2+ 和 TRPC 通道电导并抑制 KNa 通道电导生成大型 DSF。我们增强大型 DSF 和 OA 生成的机制模型可能与深部组织切口疼痛特别相关，其中血小板聚集体在或附近释放 5-HT 伤口。深部组织切口已被证明会诱发伤害感受器的 OA 和自发疼痛行为受伤后几天。目前尚不清楚切口部位或附近的 5-HT 或 PKA 是否在 OA 中发挥作用以及切口后持续的疼痛。在目标 3 中，我们将确定外周 5-HT 和 PKA 是否有助于术后疼痛模型中的疼痛行为。这项拟议的研究将为分子生物学提供新的见解伤害感受器中与疼痛相关的持续活动的机制以及外周血清素的贡献和 PKA 对术后疼痛模型中持续疼痛和诱发疼痛的影响。