The role of TRPA1 neurons in inflammatory pain

描述(由申请人提供)：有有限数量的健壮动物模型可用于检测与急性和慢性疼痛相关的表型变化。这不仅适用于动物行为，也适用于损伤部位相关组织发生变化的机械细节，包括伤害性神经纤维。为了更深入地了解炎症是如何导致疼痛和过度兴奋的，了解这种类型的病理如何导致介导这种敏化的特定传入神经元队列中的分子、细胞和解剖学变化将是有益的。在分子水平上，Trp离子通道家族的成员在体内急性和持续性疼痛的形成中发挥着重要作用，尤其是刺激性受体通道TRPA1。TRPA1对机械刺激和热刺激的炎性超敏反应的形成至关重要，这意味着表达TRPA1的传入神经元在炎症信号转导中具有同等重要的作用。在这里，我们建议通过建立两个小鼠模型来研究这些神经元的属性，但不一定是通道本身，利用这两个模型，我们将检查它们的表型和形态如何随着炎症超敏反应的变化而变化，并通过细胞消融来确定它们在急性和炎症信号中的必要性。我们已经开始了转基因小鼠的创建，在其中表达TRPA1的神经元被荧光轴突示踪剂标记，我们将使用它来建立体内TRPA1神经元外周和中枢终末的神经化学表型和形态。这些分析将在正常条件下进行，并在小鼠炎症损伤模型的背景下进行。接下来，使用这一新开发的转基因策略，我们将针对TRPA1神经元进行条件消融，并在体内确定它们在急性和持续性疼痛中的作用。总体而言，这些探索性研究将梳理出这一特定神经元群体在躯体感觉信号和炎性超敏反应形成中的作用，并开发新的动物模型，选择性地以TRPA1神经元为靶点，用于未来对其生理和功能的研究。 公共卫生相关性：我们的研究将通过表征组织损伤引起的特定传入细胞类型的形态变化，为导致与炎症相关的持续性疼痛的神经机制提供洞察力。此外，我们将确定在炎性疼痛的形成和维持中特定传入群体的必要性，从而提供可用于缓解这些衰弱状况的新的治疗靶点。

DESCRIPTION (provided by applicant): There are a limited number of robust animal models that can be used to assay phenotypic changes associated with acute and chronic pain. This is true not only for animal behaviors, but also with respect to mechanistic details of changes that occur in relevant tissues at the site of injury, including nociceptive nerve fibers. For a more in-depth understanding of how inflammation leads to pain and hyperexcitability, it will be informative to know how this type of pathology leads to molecular, cellular, and anatomical changes in specific cohorts of afferent neurons that mediate such sensitization. At the molecular level, members of the TRP family of ion channels play essential roles in the formation of both acute and persistent pain in vivo, particularly the irritant receptor channel TRPA1. TRPA1 is critical for the development of inflammatory hypersensitivity to both mechanical and thermal stimuli, implicating the afferent neurons expressing TRPA1 as being of equal importance in inflammatory signaling. Here we propose to address the property of these neurons, but not necessarily the channel itself, with the generation of two mouse models with which we will examine how their phenotype and morphology changes with inflammatory hypersensitivity, and through cell ablation, will determine their necessity in acute and inflammatory signaling. We have initiated the creation of transgenic mice in which neurons that express TRPA1 are labeled with a fluorescent axonal tracer which we will use to establish the neurochemical phenotype and morphology of the peripheral and central terminations of TRPA1 neurons in vivo. These analyses will be done under normal conditions and in the context of mouse models of inflammatory injury. Next, using this newly developed transgenic strategy, we will target TRPA1 neurons for conditional ablation and determine their role in acute and persistent pain in vivo. As whole, these exploratory studies will tease out the role of this specific neuronal population in somatosensory signaling and the formation of inflammatory hypersensitivity, as well as develop novel animal models that selectively target TRPA1 neurons for future studies into their physiology and function. PUBLIC HEALTH RELEVANCE: Our studies will provide insights into the neuronal mechanisms that lead to the persistent pain associated with inflammation by characterizing the morphological changes induced in specific afferent cell types by tissue injury. Moreover, we will determine the necessity of a specific afferent population in the formation and maintenance of inflammatory pain, thereby providing novel therapeutic targets that can be used to alleviate these debilitating conditions.