Glucose-Sensing and Intestinal Feedback Inhibition

葡萄糖感应和肠道反馈抑制

• 批准号: 6728281
• 负责人: Helen E Raybould
• 金额: $ 31.41万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6728281
• 关键词: biological signal transduction; blood glucose; capsaicin; chromaffin cells; dietary carbohydrates; digestion; electrophysiology; gastric mucosa; gastrointestinal absorption /transport; gastrointestinal system; glucose transport; immunocytochemistry; laboratory rat; nutrition related tag; polymerase chain reaction; receptor expression; serotonin; serotonin receptor; tissue /cell culture; vagus nerve; visceral afferent nerve; western blottings

DESCRIPTION (provided by applicant): The ability of nutrients in the intestinal lumen to initiate changes in secretory and motor function in the gastrointestinal tract is well established. The precise nature of the "sensors" is not well characterized. Dietary carbohydrate in the intestinal lumen is well established to inhibit gastric emptying and food intake. The hypothesis to be tested is that dietary carbohydrate-induced inhibition of gastric emptying is dependent on binding of glucose to the sodium-glucose co-transporter SGLT on enterochromaffin (EC) cells, leading to release of 5-hydroxytryptamine (5-HT) that activates 5-HT3 receptors on extrinsic afferent nerve terminals in the intestinal mucosa. To test this hypothesis, studies are proposed to determine that (1) inhibition of gastric emptying by glucose is dependent on binding of glucose to SGLT; (2) glucose-induced release of 5-HT from EC cells is dependent on binding of glucose to SGLT; (3) activation of vagal and spinal afferents in response to glucose is dependent on SGLT and 5-HT3 receptor activation and (4) to demonstrate the expression of 5-HT3 receptors on vagal and spinal afferent terminals innervating the duodenum and their association with EC cells. The role of SGLT-1 and 5-HT release in glucose-induced inhibition of gastric emptying will be determined in awake rats by intestinal perfusion of analogues of glucose that are or are not substrates for SGLT, and the role of binding to SGLT will be determined by infusion of phloridzin that binds but is not internalized. Finally, the role of sodium ions or protons will be determined by alteration of their concentrations in intestinal glucose perfusates. 5-HT secretion will be measured in vitro from BON cells, a model for native EC cells, to determine that glucose acts directly on EC cells. The expression of SGLT by BON cells and native EC cells will be determined by measurement of expression of SGLT protein by Western blot and by immunocytochemistry. Duodenal vagal and spinal afferent discharge will be measured to determine whether glucose activates extrinsic afferent fiber activity and whether this is mediated by SGLT and a 5-HT3-receptor pathway. The cellular sites of expression of 5-HT3 receptors in the intestinal wall and their origins will be determined in immunohistochemical studies using antisera raised to the 5-HT3 receptor in tissue from intact, capsaicin-treated and extrinsically denervated rats. The relationship between primary afferent nerve terminals expressing 5-HT3 receptors and EC cells expressing 5-HT will be determined in double labeling experiments. These studies address sensory transduction in the gastrointestinal tract, which is important in the regulation of normal digestive function. There is evidence that sensory function of the intestine is altered in pathological conditions such as inflammatory bowel disease, functional bowel disease and obesity. A greater understanding of these sensory mechanisms will help in understanding the pathophysiology of these diseases.

描述（由申请人提供）：已经很好地确定了肠腔中的营养物质在胃肠道中启动分泌和运动功能变化的能力。 “传感器”的确切性质没有很好地表征。肠腔中的饮食碳水化合物已得到很好的确定，可抑制胃排空和食物摄入。 要测试的假说是，饮食中碳水化合物诱导的胃排空抑制作用取决于葡萄糖与肠磷脂细胞（EC）细胞上葡萄糖与钠 - 葡萄糖的共发sglt结合，从而导致5-Hydroxyptamine（5-HT）的释放，从而释放了5-型Hydtryptamine（5-ht）的固定剂，从而在5-型固定剂中释放了固定剂的构造序列，从而介绍了固定型辅助剂的构造，从而释放了固定的固定剂，并释放了固定型的辅助剂，并释放了固定的固定剂。粘膜。 为了检验这一假设，提出了研究以确定（1）葡萄糖对胃排空的抑制取决于葡萄糖与SGLT的结合； （2）葡萄糖诱导的5-HT从EC细胞中释放，取决于葡萄糖与SGLT的结合； （3）对葡萄糖的响应而对迷走神经和脊柱传入的激活取决于SGLT和5-HT3受体激活，并且（4）证明了在迷走神经和脊柱传入末端的5-HT3受体的表达，该末端将十二指肠及其与EC细胞的关联支配。 SGLT-1和5-HT释放在葡萄糖诱导的胃排空抑制作用中的作用将在清醒大鼠中通过肠道灌注的肠道灌注是SGLT的葡萄糖类似物的肠道灌注，而不是SGLT底物的作用，并且通过输注菲洛里德蛋白的结合而不能确定与SGLT结合的作用。 最后，钠离子或质子的作用将取决于其在肠道葡萄糖灌注液中的浓度的改变。 5-HT分泌将在体外测量BON细胞（BON细胞），该模型是天然EC细胞的模型，以确定葡萄糖直接作用于EC细胞。 BON细胞和天然EC细胞的SGLT表达将通过通过蛋白质印迹和免疫细胞化学测量SGLT蛋白的表达来确定。 将测量十二指肠迷走神经和脊柱传入排放，以确定葡萄糖是否激活外部传入纤维活性，以及​​这是否是由SGLT和5-HT3受体途径介导的。 肠壁中5-HT3受体表达的细胞位点及其起源将在免疫组织化学研究中使用完整，辣椒素治疗和外在剥离的大鼠在组织中提高至5-HT3受体的抗血清。 表达5-HT3受体的主要传入神经末端与表达5-HT的EC细胞之间的关系将在双重标记实验中确定。 这些研究涉及胃肠道的感觉转导，这对于调节正常消化功能很重要。 有证据表明，肠道的感觉功能在病理状况（例如炎症性肠病，功能性肠病和肥胖症）中发生了改变。 对这些感官机制有更深入的了解将有助于理解这些疾病的病理生理。