Central Molecular Mechanisms of Stress-Induced Visceral Hypersensitivity

描述(由申请人提供)：肠易激综合征(IBS)是一种慢性功能性胃肠道(GI)疾病，其显著症状是剧烈的腹痛，伴随着排便习惯的改变，没有任何可识别的疾病。虽然IBS的原因尚不清楚，但临床证据表明，腹痛与压力和焦虑之间存在关系，这表明这些患者的大脑对胃肠道信号的处理发生了变化。使用临床前模型，我们以前已经证明，杏仁核的激活，大脑中调节压力和焦虑的区域，已经在临床研究中被发现，可以在大鼠中引起焦虑和胃肠道疼痛/超敏。此外，在这个具有类似IBS症状的动物模型中，我们随后证明了用防止应激激素影响的药物治疗啮齿动物可以逆转焦虑和疼痛。虽然我们已经在这个模型中获得了一些关于大脑如何调节过敏性的见解，但仍不清楚的是“杏仁核中哪些基因调节焦虑和胃肠道疼痛？”为了解决这个问题，这个项目将使用两个具体的目标：1)研究杏仁核中应激激素的表达如何在患有诱导性焦虑和GI过敏的动物中发生变化。为此，我们将监测两个互补动物模型中基因和蛋白质的表达，以确定哪些基因对IBS样症状负责。2)确定阻止杏仁核应激激素的变化是否可以防止焦虑和胃肠道疼痛的发展。在这一目标中，通过防止我们的模型中杏仁核水平的基因表达增加，我们将提供额外的证据，证明在GI过敏症和焦虑的共同调节中发挥核心作用。为了实现这些具体目标，该导师Greenwood-Van Meerveld博士组建了一支经验丰富的合作者团队，为学员Anthony C.Johnson先生提供必要的工具，以执行必要的分子技术，以监测全部(定量逆转录聚合酶链式反应，Western blotting)和局部(原位杂交，免疫组织化学)基因和蛋白的表达。这些分子技术将补充她在类似IBS的动物模型中提供的关于焦虑和疼痛的行为测量的培训。本项目中提出的实验的成功完成将为应激诱导结肠超敏反应的分子机制提供更多的证据，为IBS的治疗提供新的治疗靶点。 公共卫生相关性：本申请中提出的目标的成功完成将为杏仁核在大鼠结肠超敏反应发展中的作用提供证据，并将为中枢敏化的分子机制提供新的见解，该分子机制可能导致肠易激综合征患者群体的慢性症状。更重要的是，我们的发现可能会为针对内脏疼痛的新疗法确定新的靶点，以改进治疗，甚至降低发生肠易激综合征的风险。

DESCRIPTION (provided by applicant): The hallmark symptom of irritable bowel syndrome (IBS), a chronic functional gastrointestinal (GI) disorder, is severe abdominal pain, associated with altered bowel habits, in the absence of any identifiable disease. While the cause of IBS is unknown, clinical evidence suggests a relationship between abdominal pain and stress and anxiety, suggesting a change in the brain's processing of GI signals in these patients. Using pre- clinical models, we have previously demonstrated that activation of the amygdala, an area of the brain that regulates stress and anxiety and has been identified in clinical studies, can induce anxiety and GI pain/hypersensitivity in the rat. Additionally in this animal model with IBS-like symptomatology, we then demonstrated that treating the rodents with drugs that prevented the effects of stress hormones reversed the anxiety and pain. While we have gained some insights into how the brain regulates hypersensitivity in this model, what remains unknown is "Which genes in the amygdala regulate anxiety and GI pain?" To address this question, this project will use two specific aims: 1) Investigate how stress hormone expression in the amygdala changes in an animal with induced-anxiety and GI hypersensitivity. In this aim, we will monitor both gene and protein expression in two complementary animal models, to determine which genes are responsible for the IBS-like symptoms. 2) Determine if blocking the changes in stress hormones in the amygdala prevents the development of anxiety and GI pain. In this aim, by preventing the increased gene expression in our models at the level of the amygdala, we will provide additional evidence for a central role in the co-regulation of GI hypersensitivity and anxiety. To achieve these specific aims, the mentor, Dr. Greenwood-Van Meerveld, has assembled a team of experienced collaborators to provide the trainee, Mr. Anthony C. Johnson, with the necessary tools to perform the molecular techniques necessary to monitor both total (quantitative reverse polymerase chain reaction, western blotting) and localized (in situ hybridization, immunohistochemistry) gene and protein expression. These molecular techniques will complement the training that she has provided on the behavioral measurements of anxiety and pain in IBS-like animal models. Successful completion of the experiments proposed in this project will provide additional evidence for the molecular mechanisms of stress-induced colonic hypersensitivity, providing new therapeutic targets for the treatment of IBS. PUBLIC HEALTH RELEVANCE: Successful completion of the aims proposed within this application will provide evidence for the role of the amygdala in the development of colonic hypersensitivity in rats and will offer new insights into the molecular mechanisms of central sensitization that likely lead to chronic symptomatology in the irritable bowel syndrome patient population. More importantly, our findings may identify novel targets for new therapies directed at visceral pain to improve the treatment or even reduce the risk for the development of irritable bowel syndrome.