Colon afferents: molecular identity, histology/morphology and hypersensitivity

描述（由申请人提供）：据估计，肠易激综合征（IBS）影响美国高达15%的人口，对生活质量产生负面影响，每年的直接和间接医疗保健费用约为300亿美元。疼痛是肠易激综合征的特征性症状，也是患者去看胃肠病医生的主要原因。越来越多的证据表明，来自结直肠传入神经的外周感觉输入增加（即，传入致敏）对于IBS相关疼痛和超敏反应的持续性是必需的。拟议的研究的目标是调查分子/神经化学身份（“化学型”）和组织学位置的功能不同的传入类在结直肠，从信息传入致敏机制，有助于结直肠超敏反应将被揭示。具体而言，一种新的离体制备的小鼠结肠直肠与神经和脊髓的连续性将被用来耦合功能研究传入电生理学与化学型评价和传入结束解剖。研究将分别在酵母聚糖或三硝基苯磺酸（TNBS）结肠内治疗诱导的内脏高敏感性长期模型的背景下进行。提出了三个具体目标。具体目标1将表征盆神经（PN）结直肠神经支配中功能不同类别传入神经的化学型。具体目标2将确定组织学位置和形态学特征的功能不同类的传入在特PN结直肠神经支配。具体目标3将探讨使用计算机模拟增强结直肠传入神经编码的潜在机制。具体目标4将通过体外研究人类肠道传入神经，探索将上述研究结果转化为治疗结直肠疼痛和超敏反应的临床靶点的可能性。组合的功能、化学型和形态学方法将允许产生关于有助于传入敏化的通道/受体的新信息，并且首次揭示结直肠感受性末梢的组织学/形态学特征。实验数据将用于构建和验证计算模拟，这将允许探索在每个功能不同的传入类中致敏的假定机制。所提出的实验的结果有可能指导具有结肠直肠传入亚类特异性的药理学化合物的开发策略。

DESCRIPTION (provided by applicant): Irritable bowel syndrome (IBS) is estimated to affect up to 15% of the population in the USA, with negative effects on quality of life and annual direct and indirect health care costs of ~30 billion U.S. dollars. Pain is the characteristic symptom of IBS and the main reason for patient visits to gastroenterologists. Accumulating evidence suggests that heightened peripheral sensory input from colorectal afferents (i.e., afferent sensitization) is necessary for the persistence of IBS-related pain and hypersensitivity. The goal of the proposed research is to investigate molecular/neurochemical identities ('chemotype') and histological locations of functionally distinct afferent classes in the colorectum, from which information about mechanisms of afferent sensitization that contribute to colorectal hypersensitivity will be revealed. Specifically, a novel ex vivo preparation of the mouse colorectum with nerves and spinal cord in continuity will be used to couple functional study of afferent electrophysiology with chemotype evaluation and afferent ending anatomy. Studies will be done in the context of long-term models of visceral hypersensitivity induced by intracolonic treatment with zymosan or trinitrobenzene sulfonic acid (TNBS), respectively. Three specific aims are proposed. Specific Aim 1 will characterize chemotype of functionally distinct classes of afferents in the pelvic nerve (PN) colorectal innervation. Specific Aim 2 will determine the histological location and morphological features of functionally distinct classes of afferents in te PN colorectal innervation. Specific Aim 3 will explore the underlying mechanisms for enhanced neural encoding of colorectal afferents using computational simulation. Specific Aim 4 will explore the possible translation of outcomes from the foregoing studies into clinic targets for management of colorectal pain and hypersensitivity by studying human intestinal afferents in vitro. The combined functional, chemotypical, and morphological approaches will allow generation of new information about channels/receptors that contribute to afferent sensitization and, for the first time, reveal histological/morphological features of colorectal receptive endings Experimental data will be used to construct and validate a computational simulation, which will allow exploration of the putative mechanism(s) for sensitization in each functionally distinct afferent class. The outcomes of the proposed experiments have the potential to guide strategies for development of pharmacological compounds that possess colorectal afferent sub-class specificity.