Pathobiology of Diabetic Gastroenteropathy

正常的胃肠动力需要维持肠神经和Cajal间质细胞（ICC）网络。本提案的总体目标是确定糖尿病胃肠病（DGE）病理生物学的基础机制。我们的初步数据表明，神经元型一氧化氮合酶/一氧化氮（nNOS/NO）和血红素加氧酶/一氧化碳（HO/CO）通路在糖尿病ICC网络的维护中发挥着重要作用。我们已经做了以下关键的初步观察：HO 1在糖尿病中上调，并作为一种保护机制，对抗糖尿病诱导的氧化应激。NO上调HO 1。nNOS的丧失是DGE发展的早期步骤，导致NO减少，HO 1上调的丧失和随后ICC数量的减少。 支持NO对ICC具有细胞保护作用的假设的是初步数据，其显示在nNOS敲除小鼠中ICC数量减少，NOS抑制剂减少ICC数量，并且NO供体增加培养物中的ICC数量。此外，在DGE患者中，nNOS表达降低，HO 1上调丢失，ICC数量减少。我们还开发了DGE的动物和人体组织模型，并开发了一种非侵入性测试来确定小鼠的胃排空。基于这项工作，我们已经产生了新的假说，即活性氧的HO 1/CO通路的上调作为一个初始的细胞保护机制，对损伤ICC的AGE和活性氧。 肠神经nNOS表达的缺失导致HO 1持续上调的缺失 导致ICC的氧化损伤。ICC丢失导致起搏器信号丢失，无法 放大神经信号和运动障碍。该提案有两个具体目标。在第一个目标，我们将测试的假设，DGE的结果从最初的损失nNOS表达和随后的损失ICC。在第二个目标中，我们将测试的假设，HO/CO途径是细胞保护ICC和HO/CO途径的异常调节导致降低ICC和随后的DGE。这些研究将采用新开发的胃排空和ICC培养技术，电生理学，免疫组织化学和分子生物学来回答所提出的问题。我们现在正处于独特的准备提供新的信息的基础DGE的发展机制。由于这项工作将确定维持ICC的基本机制，因此它也对进一步理解与ICC数量和功能障碍相关的许多动力障碍的病理生理学具有意义。

Normal gastrointestinal motility requires maintenance of enteric nerves and the networks of interstitial cells of Cajal (ICC). The overall objective of this proposal is to identify the mechanisms that underlie the pathobiology of diabetic gastroenteropathy (DGE). Our preliminary data suggest a central role for the neuronal nitric oxide synthase/nitric oxide (nNOS/NO) and the heme oxygenase/carbon monoxide (HO/CO) pathways in the maintenance of ICC networks in diabetes. We have made the following key preliminary observations: HO1 is up-regulated in diabetes and serves as a protective mechanism against diabetes-induced oxidative stress. NO up-regulates HO1. Loss of nNOS is an early step in the development of DGE resulting in decrease in NO, loss of up-regulation of HO1 and subsequent decrease in ICC numbers. Supporting the hypothesis that NO is cytoprotective to ICC are preliminary data that show that ICC numbers are decreased in nNOS knockout mice, NOS inhibitors decrease ICC numbers, and NO donors increase ICC numbers in culture. Also, nNOS expression is decreased, HO1 up-regulation is lost and ICC numbers are decreased in patients with DGE. We have also developed animal and human tissue models for DGE and developed a non-invasive test to determine gastric emptying in mice. Based on this work we have generated the novel hypothesis that up-regulation of the HO1/CO pathway by reactive oxygen species serves as an initial cytoprotective mechanism against damage to ICC by AGE and reactive oxygen species. Loss of nNOS expression from enteric nerves leads to loss of continued up-regulation of HO1 resulting in oxidative injury to ICC. Loss of ICC results in loss of the pacemaker signal, failure to amplify neuronal signals and dysmotility. The proposal has two specific aims. In the first aim we will test the hypothesis that DGE results from initial loss of nNOS expression and subsequent loss of ICC. In the second aim we will test the hypothesis that the HO/CO pathway is cytoprotective to ICC and that aberrant regulation of the HO/CO pathway results in decreased ICC and subsequent DGE. The studies will employ newly developed gastric emptying and ICC culture techniques, electrophysiology, immunohistochemistry, and molecular biology to answer the questions raised. We are now uniquely poised to provide new information on the mechanisms that underlie the development of DGE. As this work will identify basic mechanisms that underlie maintenance of ICC it also has implications for further understanding the pathophysioIogy of many of the motility disorders linked to disorders in ICC number and function.