CRF2 Receptor Modulation of Colonic Response to Stress

描述（由申请人提供）：压力对肠道产生深远的影响，应激反应的改变与功能障碍有关，包括肠易激综合征（IBS）。脑促肾上腺皮质激素释放因子（CRF）和CRF受体1 （CRF1）在结肠对应激的运动、焦虑和内分泌反应中起重要作用，而CRF2的激活则抑制应激的行为和内分泌反应。基于我们的初步数据，目的是在有意识的大鼠中验证外周CRF2阻碍CRF1受体介导的应激和crf诱导的结肠运动和内脏痛觉过敏作为应激应对机制的一部分的新概念。具体目标1将建立外周激活CRF2抵消CRF和应激对结肠运动功能的刺激作用。这将通过以下方式实现：1)在体内和体外表征外周CRF2激动剂尿皮质素2 （ucn2）对CRF1优先激动剂、CRF1-和应激诱导的结肠运动刺激的抑制作用；2)确定参与CRF2作用的神经介质和结肠组织中表达CRF2的细胞的化学编码。特异性目标2将证明外周CRF2的激活可以减弱结肠膨胀（CRD）和应激性内脏疼痛。这将通过：1)评估外周注射ucn2对CRD和应激性内脏疼痛增强的抑制作用；2)确定ucn2减轻内脏疼痛对CRD和应激反应的神经元和化学途径。CRF2介导的内脏疼痛调节的机制将通过功能（内脏疼痛到CRD）和电生理（体外结肠传入信号通过扩张激活）测量，以及腰骶脊髓Fos的诱导和Erk的激活来确定。新的工具，如RNAi沉默结肠CRF和CRF2受体基因，超声显微测量体外运动和激光捕获显微解剖技术，以确定CRF2和配体的组织分布，高选择性的CRF受体和配体抗体和CRF2拮抗剂将在这些研究中使用。阐明外周CRF2抑制应激和CRF相关的结肠运动改变和内脏超敏反应的作用和机制，将对IBS等功能障碍具有重要的临床意义，因为应激、CRF信号通路和症状之间的联系越来越被认识到。

DESCRIPTION (provided by applicant): Stress exerts a profound effect on the gut and altered stress response is associated with functional disorders, including irritable bowel syndrome (IBS). Brain corticotropin-releasing factor (CRF) and CRF receptor 1 (CRF1) play an important role in the colonic motor, anxiogenic and endocrine responses to stress, while activation of CRF2 restrains the behavioral and endocrine responses to stress. The objectives, based on our preliminary data, are to test in conscious rats the novel concept that peripheral CRF2 impedes the CRF1 receptor-mediated stress- and CRF-induced colonic motility and visceral hyperalgesia as part of a stress-coping mechanism. Specific aim 1 will establish that peripheral activation of CRF2 counteracts the stimulatory effect of CRF and stress on colonic motor function. This will be achieved by: 1) characterizing, in vivo and in vitro, the inhibitory action of peripheral CRF2 agonist, urocortin 2 (Ucn 2) on CRF1 preferential agonist, oCRF1- and stress-induced colonic motor stimulation; and 2) determinining the neuromediators involved in CRF2 action and the chemical coding of cells expressing CRF2 in the colonic tissue. Specific aim 2 will demonstrate that peripheral CRF2 activation blunts colorectal distention (CRD) and stress-induced visceral pain. This will be achieved by: 1) assessing the inhibitory effect of peripheral injection of Ucn 2 against CRD and stress-induced enhanced visceral pain ; and 2) identifying the neuronal and chemical pathways by which Ucn 2 attenuates the visceral pain response to CRD and stress. The mechanisms involved in the CRF2 mediated modulation of visceral pain will be determined by functional (visceral pain to CRD) and electrophysiological (in vitro colonic afferent activation by distention) measurements, as well as induction of Fos and activation of Erk in the lumbo-sacral spinal cord. Novel tools such as RNAi to silence colonic CRF and CRF2 receptor gene, ultrasonomicrometry for in vitro motility measurements and laser capture microdissection techniques to determine tissue distribution of CRF2 and ligands, highly selective CRF receptor and ligand antibodies and CRF2 antagonists will be used in these studies. The elucidation of the effects and mechanisms through which peripheral CRF2 dampen stress- and CRF-related colonic motor alteration and visceral hypersensitivity will have important clinical implications in functional disorders such as IBS, for which a link between stress, CRF signaling pathway and symptoms are increasingly recognized.