Pain, Nociception and the Amygdala

描述（由申请人提供）：关节炎疼痛与负面情绪（如抑郁和焦虑）显著相关。杏仁核在情绪和情感障碍中起着关键作用。在之前的研究中，我们将杏仁核中央核（CeA）的囊外部分描述为“伤害性杏仁核”。我们发现，在关节炎疼痛模型中，CeA中的多感受性神经元具有伤害性可塑性，这是由谷氨酸受体的增强功能介导并依赖于谷氨酸受体的增强：伤害性传递通过mGluR1亚型的突触前代谢性谷氨酸受体增强，神经元兴奋性通过CeA中突触后n -甲基-d -天冬氨酸（NMDA）受体的蛋白激酶a （PKA）依赖性磷酸化而增强。然而，PKA活化的机制尚不清楚。在我们的高岭土/卡拉胶关节炎疼痛模型中，我们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）在杏仁核中的作用。CGRP和CRF在杏仁核中含量特别高，它们的g蛋白偶联受体与PKA信号转导通路直接相关。我们将采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定义CGRP、CRF及其受体在CeA中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、听觉和超声波发声，并在体内使用麻醉大鼠的细胞外单单元记录和在体外使用大鼠脑切片的全细胞膜片钳来验证以下假设：CGRP通过CGRP1受体产生促伤害作用，是关节炎疼痛中CeA伤害性可塑性所必需的。2. CRF通过CRF1受体具有抗伤害作用，通过CeA中的CRF2受体具有促伤害作用。在关节炎疼痛中，前伤害性作用而非抗伤害性作用被增强，这是痛觉可塑性所必需的。具体目标是：1.；分析关节炎疼痛相关行为学(a)、体内电生理(b)和体外电生理(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. 定义CRF1和CRF2受体激动剂和拮抗剂对疼痛行为(a)和体内电生理(b)和体外电生理(c)的促进和抗伤害性作用和信号转导机制，以及关节炎模型中伤害性可塑性的测量。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，杏仁核是在与关节炎疼痛显著相关的情感性疾病中起关键作用的大脑区域。创新和综合的行为和电生理在体内和体外的方法也将有助于有价值的见解，中枢非阿片神经肽受体作为疼痛缓解的新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.