Role of CCK Receptor in Acute Pancreatitis Pathogenesis

描述(申请人提供)：急性胰腺炎是一种常见的疾病，具有显著的发病率和死亡率，但由于致病机制尚不清楚，目前尚无专门的治疗方法。本研究的目的是阐明胆石性急性胰腺炎发病机制的早期事件。我们使用胆胰管结扎诱导的急性胰腺炎的大鼠模型作为实验推论。胆胰液从肠道排出，通过CCK-AR机制产生反馈的胰腺外分泌刺激。CCK-AR在疾病发病机制中的作用尚不清楚。我们的初步研究首次证明CCK-AR介导的胰腺腺泡细胞过度刺激在疾病发病机制中起重要作用，CCK-AR的诱导发生在胆管结扎后1小时内。我们假设CCK-AR介导的信号转导的病理性放大加剧了疾病的发病机制。我们提出实验来验证这一假说，并追求这些特定的目标：1)表征CCK-AR在胆管阻塞诱导的急性胰腺炎发病机制中的作用。2)研究CCK-AR在胆管阻塞性急性胰腺炎中的表达及调控。3)明确CCK-AR介导的信号转导通路在胆管阻塞所致急性胰腺炎中的作用。将进行与放射性标记配体的竞争性结合分析，以研究受体的数量、特异性和亲和力。受体的敏感性和活性将通过测量下游信号(环磷酸腺苷、肌醇磷酸)来确定。诱导受体和天然受体之间的差异将取决于功能特征的改变和细胞内信号转导途径的扰动。急性胰腺炎时G蛋白偶联异常可能显著增加CCK-AR亲和力，并使细胞内信号持续大量放大，这可能在疾病的发病机制中具有深远的意义。这项提议的一个创新特征是使用了一种原始的手术模型--“供体大鼠模型”，它为研究疾病的发病机制提供了一个独特的机会。这项研究的意义和与健康相关的最终目标是阐明疾病发病机制，为建立旨在降低急性胰腺炎发病率和死亡率的新治疗方案提供理论基础。

DESCRIPTION (provided by applicant): Acute pancreatitis is a common disease with significant morbidity and mortality but no specific treatment is available as the pathogenic mechanisms are not known. The purpose of this research proposal is to elucidate early events in pathogenesis of gallstone-induced acute pancreatitis. We use the rat model of bile-pancreatic duct ligation-induced acute pancreatitis as an experimental corollary. Bile-pancreatic juice exclusion from gut causes feedback exocrine pancreatic stimulation via cholecystokinin-A receptor (CCK-AR) mechanisms. The role of the CCK-AR in disease pathogenesis is not known. Our preliminary studies provide the first evidence that CCK-AR mediated pancreatic acinar cell hyperstimulation plays a contributory role in disease pathogenesis and that induction of CCK-AR occurs within one hour of duct ligation. We hypothesize that pathological amplification of CCK-AR mediated signal transduction exacerbates disease pathogenesis. We propose experiments to test this hypothesis and pursue these specific aims: 1) Characterize the role of the CCK-AR in duct occlusion-induced acute pancreatitis pathogenesis. 2) Characterize the expression and regulation of the CCK-AR in duct occlusion-induced acute pancreatitis. 3) Characterize the CCK-AR mediated signal transduction pathway in duct occlusion-induced acute pancreatitis. Competitive binding assays with radiolabeled ligand will be done to study receptor number, specificity, and affinity. Receptor sensitivity and activity will be determined by measuring downstream signals (cyclic AMP, inositol phosphate). Differences between the induced and native receptor will be determined both in terms of altered functional characteristics and perturbations in intracellular signal transduction pathways. The possibility that promiscuous G-protein coupling in acute pancreatitis could drastically increase CCK-AR affinity and also perpetuate a grossly amplified intracellular signal may have profound implications in mechanisms of disease pathogenesis. An innovative feature of this proposal is the use of an original surgical model, "The Donor Rat Model", that provides a unique opportunity to investigate disease pathogenesis. The significance and health-relatedness of this research endeavor is its ultimate goal to elucidate mechanisms of disease pathogenesis that provide the rationale to base new treatment protocols intended to reduce the morbidity and mortality of acute pancreatitis.