BRADYKININ IN ENTERIC NEUROIMMUNE COMMUNICATION

本计画将利用电生理记录方法及分子生物学技术研究基因表现，以验证缓激肽为肠神经系统重要发炎介质的假说。初步/可行性研究发现，缓激肽兴奋神经元并在ENS中产生突触前抑制。这些作用部分是通过激活环加氧酶（包括组成型环加氧酶-1（考克斯- 1）和诱导型环加氧酶-2（考克斯-2））后内源性前列腺素（PG）释放增加介导的。本研究旨在探讨缓激肽对电生理反应的影响以及缓激肽BZ受体、考克斯- 1和考克斯-2蛋白及其基因在ENS中的功能性表达，以验证缓激肽激活BZ受体、激活考克斯- 1和诱导表达考克斯-2进而催化花生四烯酸合成前列腺素的假说。PG的释放似乎是部分负责突触前抑制神经递质的释放和突触后肠神经元的兴奋。这些效应的综合输出是一种典型的肠道行为模式，由跨粘膜的大量水和电解质分泌组成，与在肠的广泛长度上传播的强大推进运动模式相协调。这在病理生理情况下尤其重要，例如缓激肽增加的炎症性肠病。目的1将确定缓激肽的行动和信号转导机制，在电生理和形态学鉴定的肠神经元在肌间和粘膜下神经丛的小肠。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中功能性表达的假设。目的3将检验B2受体由特定肠神经元和/或神经胶质表达的假设。目的4将确定假定参与缓激肽作用的PG。目的5鉴定缓激肽作用后考克斯-2蛋白和mRNA表达的ENS细胞类型。这项研究的总体目标是更好地了解缓激肽在动力障碍、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.