Pain, Nociception and the Amygdala

描述(由申请者提供)：关节炎疼痛与消极情绪显著相关，如抑郁和焦虑。杏仁核在情绪性和情感性障碍中起着关键作用。在之前的授权期内，我们将杏仁中央核(CEA)的囊外部分描绘为“伤害性杏仁核”。我们发现，在关节炎痛模型中，CEA中的多感受性神经元发展伤害性可塑性，这是由谷氨酸受体功能增强所介导和依赖的：伤害性传递通过突触前的mGluR1亚型代谢性谷氨酸受体增强，神经元的兴奋性通过依赖蛋白激酶A(PKA)的突触后N-甲基-D-天冬氨酸(NMDA)受体的磷酸化而增强。然而，PKA的激活机制尚不清楚。这项拟议的研究将分析两种主要的非阿片类神经肽，降钙素基因相关肽(CGRP)和促肾上腺皮质激素释放因子(CRF)在我们的高岭土/卡拉胶关节炎疼痛模型中对杏仁核的作用。CGRP和CRF在杏仁核中的水平特别高，它们的G蛋白偶联受体直接与PKA信号转导途径联系在一起。我们将使用一种创新的综合药理学方法，结合行为测试和体内、体外电生理学，在系统和细胞水平上确定CGRP、CRF及其受体在CEA的伤害性加工和疼痛相关可塑性中的作用。我们将测量清醒大鼠的自发探索行为、听觉和超声发声，并使用麻醉大鼠体内的细胞外单位记录和体外大鼠脑片的全细胞膜片钳技术来验证以下假设：1.CGRP通过CGRP1受体产生伤害感受效应，是关节炎疼痛CEA伤害性可塑性所必需的。2.CRF通过CRF1受体发挥抗伤害性作用，通过CRF2受体发挥促伤害性作用。在关节炎疼痛的CEA中，促伤害性而不是抗伤害性的作用被增强，并且是伤害性可塑性所必需的。具体目的是：1.分析关节炎痛相关行为(A)、体内电生理(B)和体外(C)CGRP受体激动剂和拮抗剂作用的变化及其信号转导机制。2.明确CRF1和CRF2受体激动剂和拮抗剂对大鼠痛觉行为(A)、体内电生理(B)和体外(C)伤害性可塑性的影响及其信号转导机制。这些研究将为非阿片类神经肽在杏仁核疼痛机制中的作用提供重要的新信息，杏仁核是大脑中的一个区域，在与关节炎疼痛密切相关的情感障碍中发挥关键作用。这一创新和综合的行为学和电生理学的体内和体外方法也将有助于深入了解中枢非阿片神经肽受体作为新的止痛靶点的潜在治疗价值。

DESCRIPTION (provided by applicant): Arthritic pain is significantly associated with negative affect, such as depression and anxiety. The amygdala plays a key role in emotionality and affective disorders. In the previous grant period we delineated the laterocapsular part of the central nucleus of the amygdala (CeA) as the "nociceptive amygdala". We showed that in a model of arthritic pain multireceptive neurons in the CeA develop nociceptive plasticity, which is mediated by and dependent on the enhanced function of glutamate receptors: nociceptive transmission is enhanced through presynaptic metabotropic glutamate receptors of the mGluR1 subtype and neuronal excitability is increased through protein kinase A (PKA)-dependent phosphorylation of postsynaptic N-methyl-D-aspartate (NMDA) receptors in the CeA. The mechanism of PKA activation, however, is unknown. The proposed studies will analyze the role of two major non-opioid neuropeptides, calcitonin gene-related peptide (CGRP) and corticotropin releasing factor (CRF), in the amygdala in our kaolin/carrageenan arthritis pain model. CGRP and CRF are present at particularly high levels in the amygdala and their G-protein-coupled receptors are directly linked to the PKA signal transduction pathway. We will use an innovative and integrative pharmacological approach that combines behavioral tests and in vivo and in vitro electrophysiology to define, at the systems and cellular levels, the role of CGRP, CRF and their receptors in nociceptive processing and pain-related plasticity in the CeA. We will measure spontaneous exploratory behavior and audible and ultrasonic vocalizations in awake rats and use extracellular single-unit recordings in anesthetized rats in vivo and whole-cell patch-clamp in rat brain slices in vitro to test the hypotheses that: 1. CGRP produces pro-nociceptive effects through CGRP1 receptors and is required for nociceptive plasticity in the CeA in arthritis pain. 2. CRF has anti-nociceptive effects through CRF1 receptors and pro-nociceptive effects through CRF2 receptors in the CeA. The pro-nociceptive, but not anti-nociceptive, actions are enhanced and required for nociceptive plasticity in the CeA in arthritis pain. Specific aims are: 1. To analyze arthritis pain-related behavioral (a), electrophysiological in vivo (b) and in vitro (c) changes of CGRP receptor agonist and antagonist effects and their signal transduction mechanisms. 2. To define pro and anti-nociceptive effects and signal transduction mechanisms of CRF1 and CRF2 receptor agonists and antagonists on pain behavior (a) and electrophysiological in vivo (b) and in vitro (c) measures of nociceptive plasticity in the arthritis model. These studies will provide important new information on the role of non-opioid neuropeptides in pain mechanisms in the amygdala, a brain area that plays a key role in affective disorders, which are significantly associated with arthritic pain. The innovative and integrative behavioral and electrophysiological in vivo and in vitro approach will also contribute valuable insight into the potential therapeutic value of central non-opioid neuropeptide receptors as novel targets for pain relief.