Mechanisms Regulating Gastrointestinal Hormone Secretion

调节胃肠激素分泌的机制

• 批准号: 8258993
• 负责人: Rodger A. Liddle
• 金额: $ 34.15万
• 依托单位: DUKE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-17 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8258993
• 关键词: Address; Amino Acids; Animals; Apical; Aromatic Amino Acids; Attention; Bile fluid; Blood; Brain; Calcium; Calcium Channel; Calcium Signaling; Calcium-Sensing Receptors; Cell physiology; Cells; Cholecystokinin; Cholecystokinin Receptor; Coupled; Data; Digestion; Distant; Eating; Endocrine; Enzymes; Fatty Acids; Fluorescence; Fluorescence Microscopy; Fluorescence-Activated Cell Sorting; Food; Gallbladder; Gastrointestinal Hormones; Gastroparesis; Green Fluorescent Proteins; Hormonal; Hormones; Human; In Vitro; Individual; Ingestion; Intestinal Mucosa; Intestines; Ion Channel; Lead; Measurement; Measures; Mediating; Membrane Potentials; Methods; Mus; Neuroendocrine Cell; Nutrient; Pancreas; Pancreatic enzyme; Phenylalanine; Physiological; Potassium Channel; Process; Property; Receptor Activation; Regulation; Role; Satiation; Second Messenger Systems; Signal Pathway; Small Intestines; Stomach; Stream; Study models; Surface; Techniques; Transgenic Mice; Tryptophan; Vagus nerve structure; enhanced green fluorescent protein; extracellular; gastrointestinal; hormone regulation; in vivo; increased appetite; insight; intestinal epithelium; mouse model; new technology; novel; patch clamp; prevent; receptor; second messenger; tool

DESCRIPTION (provided by applicant): Gastrointestinal hormones are produced by discrete neuroendocrine cells which are scattered throughout the intestine. Most GI hormone-containing cells reside within the intestinal mucosa and are often oriented with their apical region open to the lumen of the intestine. Cholecystokinin (CCK) is a prototypical gastrointestinal hormone that regulates gallbladder contraction, pancreatic enzyme secretion, delays gastric emptying, and induces satiety. As is typical of most GI hormones, CCK is secreted into the blood stream after ingestion of a meal. It is generally believed that nutrients stimulate CCK release but the cellular mechanisms regulating CCK cell function are largely unknown. Recently the PI has developed a method for isolating and characterizing individual, viable, native intestinal CCK cells and by highly enriching these cells it has been possible to study CCK secretion in vitro, identify receptors on these cells and investigate second messenger signaling pathways involved in regulated hormone secretion. Together these approaches have the ability to provide unique insights into the mechanisms by which nutrients may stimulate CCK secretion. Importantly, the PI has preliminary data that CCK cells express the calcium-sensing receptor (CaSR) and that CaSR mediates amino acid-induced CCK secretion. The PI will use complementary techniques to study the regulation of hormone secretion. These include: (1) isolation and identification of native CCK cells, (2) measurements of CCK secretion in vivo and in vitro, (3) quantification of intracellular calcium fluorescence, and (4) characterization of electrophysiological properties measured by whole-cell patch clamp recordings. The central hypothesis of this application is that gastrointestinal hormone secreting cels are electrically excitable cells whose secretion is regulated by receptor and ion channel activation. The overall purpose of this proposal is to understand the physiological regulators of GI endocrine cells with the initial focus on how amino acids control CCK secretion. Characterization of CaSR and its relationship to ion channel activation on CCK cells will be addressed by the following Specific Aims: 1. To characterize the role of CaSR in the regulation of CCK secretion in isolated CCK cells in vitro and in mice in vivo. 2. To determine effects of CaSR activation on calcium signaling in CCK cells. 3. To characterize the electrophysiological properties of CCK cells and evaluate CaSR regulation of membrane potential, and potassium channel and calcium channel activities. Each of these aims will focus on regulation of CaSR as a critical step in the regulation of amino acid-stimulated CCK secretion. More globally, these aims should provide considerable insight into the mechanisms by which GI endocrine cells are regulated by nutrients known to be important in the control of hormone secretion. PUBLIC HEALTH RELEVANCE: Cholecystokinin (CCK) is a major gastrointestinal hormone that is important in many digestive processes. Upon ingestion of a meal, CCK is released from the upper small intestine and acts on the pancreas to secrete digestive enzymes, the gallbladder to release bile, the stomach to prevent excess delivery of food to the intestine, and the brain through the vagus nerve to reduce food intake. Together these actions coordinate the ingestion and digestion of food. Despite these important effects, little is known about the control of CCK secretion. Specifically, the cellular mechanisms by which nutrients regulate CCK secretion are largely unknown. With new technologies that are now available to the PI, the current proposal will define and characterize a receptor that explains how amino acids stimulate hormone secretion. This receptor is coupled to regulation of ion channels that are involved in regulating CCK secretion. These studies should greatly expand our understanding of the nutrient regulation of hormone secretion. It is conceivable that these studies could lead to novel (luminally directed) therapies to regulate CCK release and, thereby, distant effects of CCK throughout the body (e.g., gallbladder contraction, satiety, etc.).

描述（由申请人提供）：胃肠激素是由分散在整个肠道中的离散神经内分泌细胞产生的。大多数含有胃肠道激素的细胞位于肠粘膜内，并且通常定向为其顶端区域向肠腔开放。胆囊收缩素 (CCK) 是一种典型的胃肠激素，可调节胆囊收缩、胰酶分泌、延迟胃排空并引起饱腹感。与大多数胃肠道激素一样，CCK 在进食后分泌到血流中。人们普遍认为营养物质刺激 CCK 释放，但调节 CCK 细胞功能的细胞机制很大程度上未知。最近，PI 开发了一种分离和表征个体、活的、天然肠道 CCK 细胞的方法，通过高度富集这些细胞，可以在体外研究 CCK 分泌，识别这些细胞上的受体，并研究参与调节的第二信使信号传导途径。激素分泌。这些方法共同能够为营养素刺激 CCK 分泌的机制提供独特的见解。重要的是，PI 拥有初步数据表明 CCK 细胞表达钙敏感受体 (CaSR)，并且 CaSR 介导氨基酸诱导的 CCK 分泌。 PI 将使用补充技术来研究激素分泌的调节。这些包括：(1) 天然 CCK 细胞的分离和鉴定，(2) 体内和体外 CCK 分泌的测量，(3) 细胞内钙荧光的定量，以及 (4) 通过全细胞贴片测量的电生理特性的表征钳位录音。本申请的中心假设是胃肠激素分泌细胞是电兴奋细胞，其分泌受到受体和离子通道激活的调节。该提案的总体目的是了解胃肠道内分泌细胞的生理调节因子，最初关注氨基酸如何控制 CCK 分泌。 CaSR 的表征及其与 CCK 细胞上离子通道激活的关系将通过以下具体目标来解决： 1. 表征 CaSR 在体外和小鼠体内分离的 CCK 细胞中 CCK 分泌调节中的作用。 2. 确定CaSR激活对CCK细胞中钙信号传导的影响。 3. 表征CCK细胞的电生理特性，评估CaSR对膜电位、钾通道和钙通道活性的调节。这些目标中的每一个都将集中于 CaSR 的调节，作为调节氨基酸刺激的 CCK 分泌的关键步骤。在全球范围内，这些目标应该提供对胃肠道内分泌细胞受已知对激素分泌控制很重要的营养物质调节的机制的深入了解。 公众健康相关性：胆囊收缩素 (CCK) 是一种主要的胃肠激素，在许多消化过程中发挥着重要作用。进食后，CCK从小肠上部释放，作用于胰腺分泌消化酶，作用于胆囊释放胆汁，作用于胃以防止食物过度输送到肠道，作用于大脑通过迷走神经减少食物摄入量。这些动作共同协调食物的摄入和消化。尽管有这些重要作用，但人们对 CCK 分泌的控制知之甚少。具体而言，营养物质调节 CCK 分泌的细胞机制在很大程度上尚不清楚。利用 PI 现在可用的新技术，当前的提案将定义并表征一种受体，该受体解释氨基酸如何刺激激素分泌。该受体与参与调节 CCK 分泌的离子通道的调节偶联。这些研究应该会极大地扩展我们对激素分泌的营养调节的理解。可以想象，这些研究可能会导致新的（发光定向）疗法来调节 CCK 释放，从而调节 CCK 对整个身体的远程影响（例如胆囊收缩、饱腹感等）。