Investigation of nociceptive endogenous opioid dynamics in the periaqueductal gray

项目摘要/摘要 慢性疼痛是一种非常普遍和令人衰弱的临床问题，对健康和 数百万人的生活质量。一种常见且相对有效的策略，为慢性阻塞性肺疾病提供急性缓解 疼痛患者是通过处方阿片类化合物。然而，阿片类镇痛剂存在大量滥用。 和过量的责任，极大地助长了目前的阿片类药物流行。这些负面后果 外源性阿片类药物在内源性MU阿片受体表达(MOR)脑内的弥散作用 疼痛编码神经回路以外的区域，它们打算进行调节。迎难而上 对有效和安全的止痛药的需求，必须开发新的、有针对性的止痛药 重点研究涉及痛觉的内源性阿片能细胞类型和神经回路(即， 痛觉)和阿片类药物诱导的镇痛。腹外侧导水管周围灰质(VlPAG)在这方面是至关重要的。 因为它可以通过MOR和细胞表达的脑啡肽产生强大的抗伤害性感觉 它包含的传入神经。然而，关于内源性阿片信号动力学的长期问题仍然存在。 在急性和慢性疼痛条件下招募的vlPAG中。这项提案将在#年开始填补这些空白 结合新工具的知识：明确神经群体中的基因重组，更具特异性 启动子病毒和荧光脑啡肽传感器。这些方法结合在一起，可以实现前所未有的 在体内获得vlPAG内源性阿片传递的突触前和突触后成分。因此， 我将验证我的中心假设，即vlPAG包含一个功能性伤害性感受MOR表达的集合 这是由脑啡肽从前脑和局部中间神经元释放来调节的，以产生抗伤害感受。在AIM 1，我将使用经典的疼痛分析来确定分子身份和钙信号活性模式 VlPAG内表达伤害性MOR的神经丛(vlPAGNoci/MOR)。我会进一步确定功能 急性炎症时vlPAGNoci/MOR神经元通过光遗传抑制在抗伤害感受中的作用 疼痛状态。在目标2中，我将识别和操纵vlPAG的两个假定的脑啡肽能输入，即局部vlPAG 杏仁中央内侧核(CEM)的中间神经元和长程内侧核投射 各自对伤害性的贡献。这些脑型传入传入如何与MOR表达相互作用 VlPAG中的神经元也将被确定。这些拟议实验的结果将推动我们的 理解急性和慢性参与和改变的内源性阿片信号转导过程 疼痛状况。通过阐明vlPAG产生的内源性阿片环路的成分 止痛，慢性疼痛的缓解可能通过未来的治疗实现，这些治疗针对这个系统，但缺乏 当前阿片类药物的有害成瘾特性。完成这项奖学金计划将实现我的 培训目标是扩大我的实验专业知识，使自己成为疼痛和阿片类药物方面的专家 神经回路。

PROJECT SUMMARY/ABSTRACT Chronic pain is a highly prevalent and debilitating clinical problem that negatively impacts the health and quality of life of millions of people. A common and relatively effective strategy to provide acute relief to chronic pain patients is through prescription of opioid compounds. However, opioid analgesics carry substantial abuse and overdose liabilities, contributing heavily to the ongoing opioid epidemic. These negative consequences of exogenous opioids result from their diffuse action at endogenous mu opioid receptor-expressing (MOR) brain regions beyond the pain-encoding neurocircuitry that they are intended to modulate. To meet the pressing demand for effective and safe analgesics, new, targeted pain therapies must be developed that emerge from focused research on the endogenous opioidergic cell types and neural circuits involved in pain perception (i.e., nociception) and opioid-induced analgesia. The ventrolateral periaqueductal gray (vlPAG) is critical in this regard as it can produce robust antinociception through MOR and the enkephalin peptides expressed by the cells and afferents it contains. Yet, long-standing questions remain concerning the endogenous opioid signaling dynamics in the vlPAG that are recruited by acute and chronic pain conditions. This proposal will begin to fill these gaps in knowledge with a combination of novel tools: genetic recombination in defined neural populations, MOR specific promoter viruses, and a fluorescent enkephalin sensor. Combined, these approaches allow for unprecedented in vivo access to the pre- and postsynaptic components of endogenous opioid transmission in the vlPAG. Thus, I will test my central hypothesis that the vlPAG contains a functional nociceptive MOR-expressing ensemble that is modulated by enkephalin release from forebrain and local interneurons to produce antinociception. In Aim 1, I will use classical pain assays to identify the molecular identity and calcium signaling activity patterns of the nociceptive MOR-expressing neural ensemble in the vlPAG (vlPAGNoci/MOR). I will further determine the functional role of vlPAGNoci/MOR neurons in antinociception through optogenetic inhibition during acute and inflammatory pain states. In Aim 2, I will identify and manipulate two putative enkephalinergic inputs to the vlPAG, local vlPAG interneurons and long-range medial nucleus of the central amygdala (CeM) projections, to determine their respective contributions to nociception. How these enkephalingeric afferents interact with the MOR-expressing neurons in the vlPAG will also be determined. The results of these proposed experiments will advance our understanding of endogenous opioid signaling processes that are engaged and altered by acute and chronic pain conditions. By elucidating the components of the endogenous opioid circuitry of the vlPAG that produce analgesia, relief from chronic pain may be realized by future therapies that target this system while lacking the harmful addictive properties of current opioid drugs. Completion of this Fellowship proposal will achieve my training goals to expand my experimental expertise and establish myself as an expert in pain and opioidergic neurocircuitry.