Identification and Validation of a Novel Central Analgesia Circuit

摘要 慢性疼痛是困扰三分之一美国人的主要健康问题。新的研究可以帮助 迫切需要开发新的止痛策略。我们的提案重点是确定和 正在验证一种新的中枢止痛回路。这个项目基于一个高度创新的假设，即 全身麻醉(GA)的强烈镇痛作用部分是通过GA介导的 内源性止痛环。在初步研究中，我们发现GABA能神经元的一个子集 位于中央杏仁核(CEA)的神经元变得强烈激活，并表达高水平的即刻 GA作用下的早期基因Fos(以下简称CeAGA神经元)。令人兴奋的是，使用我们最新开发的 被称为CANe(捕获激活的神经元集合)的活动依赖标记系统，我们能够 捕获CeAGA神经元，发现激活这些神经元会产生深刻的疼痛抑制作用 急性疼痛模型和慢性口面部神经病理性疼痛模型的效果。 基于这些令人兴奋的初步结果，我们建议鉴定和验证CeAGA神经元的止痛剂 在不同实验室进行的多个小鼠疼痛模型中的作用(Wang和Ji，co-Pi)。在目标1中，我们将 系统地激活和沉默CeAGA止痛神经元，并测试这种双向刺激的后果。 调节疼痛的感觉辨别和情绪情感方面的定向手法 在幼稚小鼠和几种急性和慢性疼痛模型小鼠模型中的交叉验证处理 在两个实验室之间。在目标2中，我们将使用最先进的活体成像技术，测试 CeAGA镇痛神经元自发活动在不同程度上严重降低的假说 慢性疼痛模型与幼稚条件的比较，导致这些模型中的疼痛过敏(由于 抑制这种内源性止痛回路)；另外，我们将使用切片电生理学 正常和慢性疼痛时CeAGA镇痛神经元内源性和诱发性的变化 可以解释体内活动变化的条件。在目标3中，根据初步结果显示 CeAGA广泛的轴突投射到许多脑区，我们将确定CeAGA的关键亚群 投射路径(S)对不同慢性疼痛模型的镇痛作用。我们希望确定共享的 在所有模型中，需要被特定亚型的CeAGA止痛神经元抑制的共同通路， 这些信息将对开发基于CeAGA的精确疗法至关重要。总而言之，这项研究 预计将识别和验证一种新的中枢止痛回路，其能量可用于治疗 慢性疼痛。

ABSTRACT Chronic pain is a major health problem that afflicts one third of Americans. New research that can aid the development of new pain-relieving strategies is urgently needed. Our proposal focuses on identifying and validating a new central analgesic circuit. This project is based on a highly innovative hypothesis that the strong analgesic effect of general anesthesia (GA) is in part carried out by GA-mediated activation of the endogenous analgesic circuits. In preliminary studies, we discovered that a subset of GABAergic neurons located in the central amygdala (CeA) become strongly activated and express high level of the immediate early gene Fos under GA (hereafter referred to as CeAGA neurons). Excitingly, using our recently developed activity-dependent tagging system called CANE (Capturing Activated Neuronal Ensemble), we were able to capture CeAGA neurons and discovered that activating these neurons exerted profound pain-suppressing effects in an acute pain model and a chronic orofacial neuropathic pain model. Based on these exciting preliminary results, we propose to identify and validate CeAGA neurons’ analgesic functions in multiple mouse pain models conducted in different labs (Wang and Ji, co-PI). In aim 1, we will systematically activate and silencing CeAGA analgesic neurons and test the consequences of such bi- directional manipulations on regulating the sensory-discriminative and emotional-affective aspects of pain processing in naïve mice and in several mouse models of acute and chronic pain models with cross validation between the two labs. In aim 2, using the state-of-the-art in vivo imaging technology, we will test the hypothesis that the spontaneous activities of CeAGA analgesic neurons are severely reduced in various chronic pain models compared to naïve conditions, leading to pain hypersensitivity in these models (due to the suppression of this endogenous analgesic circuit); and complimentary, we will use slice electrophysiology to examine changes in intrinsic and evoked properties of CeAGA analgesic neurons in normal and chronic pain conditions which may explain the altered in vivo activities. In aim 3, based on preliminary results showing extensive axonal projections of CeAGA to many brain areas, we will identify the critical subsets of CeAGA projection pathway(s) for their analgesic effect in different chronic pain models. We expect to identify shared common pathways that need to suppressed by specific subtypes of CeAGA analgesic neurons in all models, and such information will be critical for developing precise CeAGA-based therapies. In summary, this research is expected to identify and validate a novel central analgesic circuit whose power can be harnessed to treat chronic pain.