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）在美国影响高达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，也是患者去胃肠科就诊的主要原因。越来越多的证据表明，来自结直肠传入的外周感觉输入增强（即传入致敏）对于ibs相关疼痛和超敏反应的持续是必要的。本研究的目的是研究结直肠中功能不同的传入类的分子/神经化学特征（“化学型”）和组织学位置，从而揭示导致结直肠超敏反应的传入致敏机制。具体来说，一种新的体外制备的小鼠结直肠神经和脊髓的连续性将用于将传入电生理学的功能研究与化学型评估和传入末端解剖相结合。研究将在长期模型的背景下进行，这些模型分别是由zymosan或三硝基苯磺酸（TNBS）在结肠内治疗引起的内脏过敏。提出了三个具体目标。特异性目的1将描述盆腔神经（PN）结直肠神经支配中功能不同类别传入神经的化学型。特异性目的2将确定PN结直肠神经支配中功能不同类别传入事件的组织学位置和形态学特征。具体目标3将探索使用计算模拟增强结肠直肠传入神经编码的潜在机制。Specific Aim 4将通过体外研究人类肠道事件，探索将上述研究结果转化为治疗结直肠疼痛和过敏的临床靶点的可能性。结合功能，化学特征和形态学方法将允许产生有关通道/受体的新信息，有助于传入致敏，并首次揭示结直肠接受末梢的组织学/形态学特征。实验数据将用于构建和验证计算模拟，这将允许探索每个功能不同的传入类致敏的假定机制。所提出的实验结果有可能指导开发具有结直肠传入亚类特异性的药理学化合物的策略。

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.