Neuronal Excitability and Motility in Colitis

结肠炎中的神经元兴奋性和运动性

• 批准号: 6763977
• 负责人: Gary M Mawe
• 金额: $ 22.8万
• 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 2006-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6763977
• 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）的显着运动障碍反映了炎症介质与肠神经系统之间的动态相互作用。虽然很明显炎症介质会触发肠神经元反应，但它们的精确靶点和作用机制尚不清楚。拟议的研究旨在阐明炎症如何调节肠道反射回路的传入成分，即肠嗜铬 (EC) 细胞和 AH 神经元。我们将检验以下假设：结肠炎与 EC 细胞中血清素 (5-HT) 的可用性增加和 AH 神经元的兴奋性增加有关，并且这些变化是由环氧合酶 2 (COX-2) 产生的前列腺素介导的。为了验证这一假设，我们将使用经过彻底验证的三硝基苯磺酸 (TNBS) 豚鼠结肠炎模型。在第一个具体目标中，我们将通过量化 5-HT 免疫反应性 EC 细胞群、粘膜 5-HT 水平、刺激诱导的 5-HT 释放以及发炎结肠粘膜对 5-HT 的摄取来评估发炎结肠中 EC 细胞的 5-HT 可用性。在具体目标 2 中，我们将测试结肠炎是否与 AH 神经元兴奋性增加有关，从而导致这些细胞响应生理刺激的激活增加。将通过评估 AH 神经元的电特性及其对 5-HT 的敏感性来研究 AH 神经元的兴奋性。此外，通过粘膜刺激对 AH 神经元的激活将通过以下方式进行评估：(1) 电生理学，(2) 使用活动标记 FM2-10，(3) 通过测量降钙素基因相关肽的释放，以及 (4) 通过测量推进运动活动。第三个具体目标将测试炎症期间诱导的 EC 细胞和 AH 神经元功能的变化是否是由 COX-2 诱导产生的前列腺素引发的。为了实现这一目标，我们将测试前列腺素是否模拟炎症对 EC 细胞和 AH 神经元的影响，并且我们将测试 TNBS 诱导的结肠炎的神经内分泌效应是否会因 COX-2 的阻断而减弱。这些研究的结果将揭示炎症和前列腺素如何改变肠神经回路传入成分的功能。这些信息将增进我们对与 IBD 相关的神经免疫整合和运动障碍机制的理解，并可能带来新的治疗方法，将 IBD 患者的运动功能恢复到正常水平。