Functional Analysis of Distinct Nociceptor Populations

描述(申请人提供)：触觉是日常生活中必不可少的。此外，触觉过敏是慢性神经性疼痛和持续性炎症性疼痛的常见问题。尽管触觉很重要，但令人惊讶的是，人们对触觉背后的分子和细胞机制知之甚少，也不知道不同的传导机制是否介导了无害和痛苦的机械刺激。瞬时受体电位Ankyrin 1(TRPA1)是一种很有前景的机械转导候选基因。有重要证据表明，TRPA1参与了体感神经元的机械转导及其在组织炎症或神经损伤后对机械刺激的敏化。此外，有争议的证据表明，TRPA1参与了神经损伤和炎症后的冷传导和冷敏化。然而，关于TRPA1在机械转导和冷转导中的具体功能仍然存在一些重要的问题。1)本实验室和其他实验室的研究表明，TRPA1在非神经性角质形成细胞和感觉神经末梢都有表达，但这两种细胞中的TRPA1对皮肤初级传入神经元对机械力或低温的净反应的贡献尚不清楚。这项计划中的实验将使用两个新的转基因小鼠品系，其中TRPA1选择性地从角质形成细胞或感觉神经元中删除，以确定任一细胞类型中的TRPA1对机械刺激和冷刺激的行为和初级传入纤维反应的贡献。2)感觉神经元或角质形成细胞中的TRPA1是否介导了质膜对机械力或冷的反应尚不清楚。在这一应用中的实验将在全细胞膜片钳记录期间使用创新的、定量的焦点机械刺激器来识别TRPA1对感觉神经元和角质形成细胞膜上的机械电流的贡献。3)机械过敏是神经性和炎症性疼痛最常见、最具破坏性的症状之一。在神经损伤或炎症后，TRPA1对初级传入纤维对机械刺激和冷刺激的敏化作用尚不清楚。这项提议中的实验将确定感觉神经元或角质形成细胞中的TRPA1是否介导了神经病理性疼痛模型和持续性外周炎症模型中发生的机械性或冷敏化。在这项提案中，使用细胞、梳理纤维和行为分析的免费特定靶点将提供一种多方面的方法来确定TRPA1在正常组织中的感觉转导以及神经病理性和炎症性疼痛中的功能作用。 公共卫生相关性：触觉在日常生活中是必不可少的。慢性神经性疼痛和持续性炎症性疼痛综合征患者会出现对触摸和寒冷温度的异常过敏。我们的目标是确定离子通道瞬时受体电位Ankyrin 1(TRPA1)在正常皮肤的触摸和冷传导中的作用，并确定其在神经病理性和炎症性疼痛模型中的作用。

DESCRIPTION (provided by applicant): Touch sensation is essential to daily life. Further, hypersensitivity to touch is a frequent problem associated with chronic neuropathic pain and persistent inflammatory pain. Despite its importance, amazingly little is known about the molecular and cellular mechanisms underlying touch sensation and whether different transduction mechanisms mediate innocuous versus painful mechanical stimuli. A promising mechanotransduction candidate is the Transient Receptor Potential Ankyrin 1 (TRPA1). Significant evidence suggests that TRPA1 contributes to mechanotransduction in somatosensory neurons and their sensitization to mechanical stimuli after tissue inflammation or nerve injury. Further, controversial evidence suggests that TRPA1 is involved in cold transduction and cold sensitization after nerve injury and inflammation. A number of important questions remain, however, about the specific functional roles of TRPA1 in mechanotransduction and cold transduction. 1) Evidence from our laboratory and others indicates that TRPA1 is expressed by non- neuronal keratinocytes, as well as sensory nerve terminals, yet the contribution of TRPA1 in either cell type to the net responses of cutaneous primary afferent neurons to mechanical force or cold temperatures is unknown. Experiments in this proposal will use two new lines of transgenic mice where TRPA1 is selectively deleted from either keratinocytes or sensory neurons to determine the contribution of TRPA1 in either cell type to behavioral and primary afferent fiber responses to mechanical and cold stimuli. 2) Whether TRPA1 in sensory neurons or keratinocytes mediates the plasma membrane response to mechanical force or cold is not clear. Experiments in this application will use an innovative, quantitative focal mechanical stimulator during whole cell patch clamp recordings to identify the contribution of TRPA1 to mechanical currents in the membrane of sensory neurons and keratinocytes. 3) Mechanical hypersensitivity is one of the most frequent, devastating symptoms associated with neuropathic and inflammatory pain. The contribution of TRPA1 to sensitization of primary afferent fibers to mechanical and cold stimuli after nerve injury or inflammation is unknown. Experiments in this proposal will determine whether TRPA1 in either sensory neurons or keratinocytes mediates the mechanical or cold sensitization that occurs in a model of neuropathic pain, and a model of persistent peripheral inflammation. In this proposal, complimentary Specific Aims using cellular, teased fiber and behavioral assays will provide a multifaceted approach to identify functional roles of TRPA1 in sensory transduction in normal tissue, and during neuropathic and inflammatory pain. PUBLIC HEALTH RELEVANCE: Touch sensation is essential to daily life. Abnormal hypersensitivity to touch and to cold temperature occurs in patients with chronic neuropathic pain and persistent inflammatory pain syndromes. Our goals are to determine the roles of the ion channel Transient Receptor Potential Ankyrin 1 (TRPA1) in touch and cold transduction in normal skin, and to identify its roles in neuropathic and inflammatory pain models.