Central Mechanisms Modulating Visceral Sensitivity

描述(由申请人提供)： 慢性胃肠道(GI)症状，如严重的腹痛和腹泻，是退伍军人从现役归来的最常见症状之一。尽管在OEF/OIF服役的退伍军人的数据很少，但最近的发现表明，出现腹痛和腹泻症状的海湾战争退伍军人(GWV)表现出内脏过敏，其特征是对内脏刺激的意识增强，类似于 功能性胃肠道疾病，如肠易激综合征(IBS)。此外，GWV和IBS患者的焦虑水平更高，据报道，压力和焦虑会加剧症状，这表明认知活动和外周自主神经活动之间存在联系。本研究的目的是阐明情绪性脑与胃肠道沟通以放大内脏疼痛信号的受体介导的特定机制(S)。这一应用的假设是杏仁核内特定的基因组反应是诱导焦虑和异常疼痛行为的基础。应用分为三个具体目标：-在特定目标1下，我们将尝试确定杏仁核糖皮质激素受体(GR)和盐皮质激素受体(MR)在焦虑和内脏疼痛中的相对重要性。利用经过验证的显示IBS的基本方面的啮齿动物模型，即焦虑伴随由i)直接将皮质酮微丸应用于杏仁中央核(CEA)或ii)反复水回避应激(Was)而引起的结肠超敏反应，我们将研究使用特异性反义寡核苷酸(ODN)抑制杏仁体基因表达是否抑制应激诱导的焦虑和疼痛的发展。为此，治疗效果的主要结果将是焦虑和结肠过敏行为测量的改变，同时伴随着基因和蛋白质表达的减少。具体目标2.具体回答这个问题：“在应激的啮齿动物模型中，导致IBS样表型的机制是什么？”我们将确定CRF是否是杏仁核GR和MR信号的共同下游靶点。为了确定i)GR和MR是否通过共同的途径调节焦虑和高敏感性，以及ii)杏仁核皮质区植入皮质醇和重复皮质醇是否使用相同的皮质激素调节途径，将CRF ODN持续注入成年大鼠的CEA。焦虑水平将在高架+迷宫和开阔场地进行测试，对肠腔扩张的敏感性将被监测内脏运动行为反应，量化为结肠扩张期间腹部痉挛的次数。在两个实验模型中，将在向CEA注射CRF OND后进行行为测量。在这一目标下，我们将为中枢神经回路中负责IBS样表型的基因组机制提供新的证据。具体目标3，我们将探索这样的假设，即终纹床核(BNST)是杏仁核神经元回路的一部分，它诱导焦虑和放大内脏疼痛反应。在这一目标下提出的实验将为回答CRF2受体BNSTAL在杏仁核皮质区升高引起的焦虑和疼痛行为中发挥作用这一问题提供基础。对退伍军人医疗保健的影响：这项建议与退伍军人管理局的病人护理任务高度相关，因为退伍军人管理局照顾的是面临严重压力的人群，这些人群往往会导致焦虑相关的障碍。成功完成本申请中提出的目标将为深入了解导致慢性腹痛的大脑-肠道功能障碍的机制提供洞察力。我们的发现可能会确定针对大脑的新治疗策略的开发目标，以改进治疗，甚至降低退伍军人发生焦虑性内脏疼痛的风险。

DESCRIPTION (provided by applicant): Chronic gastrointestinal (GI) symptoms, such as severe abdominal pain and diarrhea are among the most frequently reported symptoms in Veterans returning from active duty. Although little data is available for Veterans that serve in OEF/OIF, recent findings have shown that Gulf War Veterans (GWV) who develop symptoms of abdominal pain and diarrhea exhibit visceral hypersensitivity characterized by increased awareness of visceral stimuli, similar to patients with functional GI disorders such as irritable bowel syndrome (IBS). Moreover, GWV and IBS patients have higher levels of anxiety and report symptoms are worsened by stress and anxiety, suggesting a link between cognitive and peripheral autonomic activity. The objective of our study is to elucidate the specific receptor-mediated mechanism(s) by which the emotional brain communicates with the GI tract to amplify visceral pain signals. The hypothesis of this application is that specific genomic responses within the amygdala underlie the induction of anxiety and abnormal pain behaviors. The application is divided in three Specific Aims:- Under Specific Aim 1, we will attempt to identify the relative importance of amygdala glucocorticoid receptors (GR) and mineralocorticoid receptors (MR) in anxiety and visceral pain. Employing validated rodent models, that exhibit the cardinal aspects of IBS, namely anxiety accompanied by colonic hypersensitivity induced by either i) direct application of corticosterone micropellets onto the central nucleus of the amygala (CeA) or ii) repeated water avoidance stress (WAS), we will investigate whether knockdown of amygdaloid gene expression using specific antisense oligodeoxynucleotides (ODNs) inhibits the development of anxiety and pain induced by stress. For this aim the primary outcome of treatment efficacy will be changes in the behavioral measurements of anxiety and colonic hypersensitivity accompanied by decreases in gene and protein expression. Specific Aim 2. To specifically answer the question: "What are the mechanisms responsible for the IBS-like phenotypes in rodent models of stress?" we will determine if CRF is the common downstream target of GR and MR signaling in the amygdala. To identify whether i) GR and MR regulate anxiety and hypersensitivity through a common pathway and whether ii) amygdala implants of CORT and repeated WAS use the same corticoid regulated pathway, CRF ODN will be continuously infused into the CeA of adult rats. The level of anxiety will be tested in the elevated plus maze and open field, and colonic sensitivity in response to luminal distension will be monitor a visceromotor behavioral response quantified as the number of abdominal cramps during a colonic distension Behavioral measurements will be conducted following administration of CRF OND to the CeA in the two experimental models. Under this aim we will provide novel evidence for the genomic mechanisms in the central neural circuit responsible for IBS-like phenotypes. Specific Aim 3, we will explore the hypothesis that the bed nucleus of the stria terminalis (BNST) is part of the neuronal circuitry from the amygdala that induces anxiety and amplified visceral pain responses. The experiment proposed under this aim will provide the foundation to answer the question - do CRF2 receptors the BNSTAL play a role in the induction of anxiety and pain behaviors in response to elevated amygdala CORT. Impact on Veterans Health Care: This proposal is highly relevant to the patient-care mission of the VA since the VA cares for a population that has been exposed to severe stress, often leading to anxiety-related disorders. Successful completion of the aims proposed within this application will offer insights into the mechanisms of brain-gut dysfunction that lead to chronic abdominal pain. Our findings may identify targets for the development of novel therapeutic strategies directed at the brain, to improve the treatment or even reduce the risk for the development of anxiety-linked visceral pain in Veterans.