Neuronal Excitability and Motility in Colitis

结肠炎中的神经元兴奋性和运动性

• 批准号: 6532078
• 负责人: Gary M Mawe
• 金额: $ 28.94万
• 依托单位: UNIVERSITY OF VERMONT & ST AGRIC COLLEGE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-12 至 2005-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6532078
• 关键词: calcitonin gene related peptide; chromaffin cells; colitis; cycloalkene; electrophysiology; enzyme induction /repression; gastrointestinal motility /pressure; guinea pigs; inflammation; intestinal mucosa; neuromuscular function; neuroregulation; neurotransmitter transport; prostaglandin endoperoxide synthase; prostaglandins; serotonin; sulfonate

DESCRIPTION (provided by applicant): The striking motor disturbances that accompany inflammatory bowel disease (IBD) reflect a dynamic interplay between inflammatory mediators and the enteric nervous system. While it is clear that inflammatory mediators trigger enteric neuronal responses, their precise targets and mechanisms of action are unknown. The proposed studies are designed to elucidate how inflammation modulates the afferent components of the reflex circuitry of the bowel, namely the enterochromaffin (EC) cells and AH neurons. We will test the hypothesis that colitis is associated with an increase in the availability of serotonin (5-HT) from EC cells and increased excitability of AH neurons, and that these changes are mediated by prostaglandins generated by cyclooxygenase 2 (COX-2). To test this hypothesis, we will use the thoroughly validated trinitrobenzene sulfonic acid (TNBS) model of colitis in the guinea pig. In the first specific aim, we will evaluate the availability of 5-HT from EC cells in the inflamed colon by quantifying the 5-HT-immunoreactive EC cell population, mucosal 5-HT levels, stimulus-induced 5-HT release, and 5-HT uptake by the mucosa of the inflamed colon. In Specific Aim 2, we will test whether colitis is associated with an increase in the excitability of AH neurons, leading to an increase in the activation of these cells in response to physiological stimuli. The excitability of AH neurons will be investigated by evaluating their electrical properties and their sensitivity to 5-HT. Furthermore, activation of AH neurons by mucosal stimulation will be evaluated (1) electrophysiologically, (2) with the activity marker, FM2-10, (3) by measuring release of calcitonin gene-related peptide, and (4) by measurement of propulsive motor activity. The third specific aim will test whether changes in EC cell and AH neuron function, that are induced during inflammation, are initiated by prostaglandins derived from the induction of COX-2. To accomplish this, we will test whether prostaglandins mimic the effects of inflammation on EC cells and on AH neurons, and we will test whether the neuroendocrine effects of TNBS-induced colitis are attenuated by blockade of COX-2. The results of these studies will reveal how inflammation and prostaglandins alter the function of the afferent components of enteric neural circuits. This information will advance our understanding of the mechanisms of neuro-immune integration and motility disturbances that are associated with IBD, and may lead to novel therapeutic approaches for restoring motor function to normal levels in individuals with IBD.

描述（由申请人提供）：伴随炎症性肠病（IBD）的显著运动障碍反映了炎症介质和肠神经系统之间的动态相互作用。虽然很明显，炎症介质触发肠神经元反应，其精确的目标和作用机制是未知的。拟议的研究旨在阐明炎症如何调节肠反射回路的传入成分，即肠嗜铬（EC）细胞和AH神经元。我们将检验结肠炎与EC细胞5-羟色胺（5-HT）的可用性增加和AH神经元兴奋性增加相关的假设，并且这些变化是由环氧合酶2（考克斯-2）产生的胡萝卜素介导的。为了检验这一假设，我们将使用经过充分验证的豚鼠结肠炎三硝基苯磺酸（TNBS）模型。在第一个具体的目标，我们将评估5-HT的可用性从EC细胞在发炎的结肠，通过量化的5-HT免疫反应EC细胞群，粘膜5-HT水平，刺激诱导的5-HT释放，和5-HT摄取发炎的结肠粘膜。在具体目标2中，我们将测试结肠炎是否与AH神经元的兴奋性增加相关，从而导致这些细胞对生理刺激的激活增加。AH神经元的兴奋性将通过评估其电特性及其对5-HT的敏感性来研究。此外，将通过（1）电生理学，（2）使用活动标记物FM 2 -10，（3）通过测量降钙素基因相关肽的释放，和（4）通过测量推进运动活动来评估粘膜刺激对AH神经元的激活。第三个具体目的是测试炎症过程中诱导的EC细胞和AH神经元功能的变化是否由源自考克斯-2诱导的洋地黄素引发。为了实现这一点，我们将测试洋地黄素是否模拟炎症对EC细胞和AH神经元的作用，并且我们将测试TNBS诱导的结肠炎的神经内分泌作用是否通过阻断考克斯-2而减弱。这些研究的结果将揭示炎症和洋地黄素如何改变肠神经回路传入成分的功能。这些信息将促进我们对与IBD相关的神经免疫整合和运动障碍机制的理解，并可能导致新的治疗方法，用于将IBD患者的运动功能恢复到正常水平。