BRADYKININ IN ENTERIC NEUROIMMUNE COMMUNICATION

本项目将使用电生理记录方法和分子生物学技术来研究基因表达，以验证缓激肽是肠道神经系统(ENS)中重要的炎症介质的假设。初步/可行性研究发现，缓激肽可兴奋神经元，并在ENS中产生突触前抑制。这些作用部分是通过激活包括结构性环氧合酶-1(COX-1)和诱导型环氧合酶-2(COX-2)在内的环氧合酶后增加内源性前列腺素(PG)的释放来实现的。本研究着重于缓激肽的电生理反应以及缓激肽BZ受体、COX-1和COX-2蛋白及其基因在ENS中的功能表达。本研究旨在验证缓激肽激活BZ型受体、激活COX-1和诱导COX-2表达进而催化花生四烯酸生物合成前列腺素的假说。PGS的释放可能是突触前抑制神经递质释放和突触后兴奋肠神经元的部分原因。这些效应的综合输出是一种刻板的肠道行为模式，包括在整个粘膜上大量分泌水和电解质，并与在广泛的肠道长度上传播的强大的推进运动模式相协调。这在炎症性肠病等病理生理情况下尤其重要，因为缓激肽升高。目的1研究缓激肽在小肠肌间神经丛和粘膜下神经丛中的作用及其信号转导机制。目的2验证B2受体蛋白和mRNA在肌间神经丛和粘膜下神经丛有功能表达的假说。目的3将验证B2受体由特定的肠神经元和/或神经胶质细胞表达的假设。AIM 4将确定假设参与缓激肽活动的PG。目的鉴定缓激肽作用后表达COX-2蛋白和mRNA的ENS细胞类型。这项研究的总体目标是更好地了解缓激肽在运动障碍、腹泻、腹痛和炎症中的作用。

This project will use methods of electrophysiological recording and molecular biological techniques for study of gene expression to test the hypothesis that bradykinin is an important inflammatory mediator in the enteric nervous system (ENS). Pilot/feasibility studies found that bradykinin excites neurons and produces presynaptic inhibition in the ENS. These effects are mediated in part by increased release of endogenous prostaglandins (PGs) following activation of cyclooxygenases including constitutive cyclooxygenase-1 (COX- 1) and inducible cyclooxygenase-2 (COX-2). This proposal focuses on electrophysiological responses to bradykinin and functional expression of the bradykinin BZ receptor, COX- 1 and COX-2 proteins and their genes in the ENS. The studies are designed to test the hypothesis that bradykinin activates Bz type receptors together with activation of COX- 1 and induced expression of COX-2 which in turn catalyze the biosynthesis of the PGs from arachidonic acid. PGs release appears to be partly responsible for presynaptic inhibition of neurotransmitters release and postsynaptic excitation of enteric neurons. Integrated output of these effects is a stereotypical pattern of intestinal behavior consisting of copious secretion of water and electrolytes across the mucosa in coordination with a powerful propulsive motility pattern that propagates over extensive lengths of bowel. This is especially important under pathophysiological circumstances such as inflammatory bowel disease where bradykinin is increased. Aim 1 will identify the actions of bradykinin and mechanisms of signal transduction in electrophysiologically and morphologically identified enteric neurons in the myenteric and submucous plexuses of the small intestine. Aim 2 will test the hypothesis that B2 receptor protein and mRNA are functionally expressed in the myenteric and submucous plexuses. Aim 3 will test the hypothesis that B2 receptors are expressed by specific enteric neurons and/or glia. Aim 4 will identify the PGs postulated to be involved in bradykinin actions. Aim 5 will identify the ENS cell types expressing COX-2 protein and mRNA after bradykinin exposure. The overall goal of the study is to better understand the role of bradykinin in motility disturbances, diarrhea, abdominal pain and inflammation.