Monell Chemical Senses Center, 3500 Market St., Philadelphia, PA 19104, USA.
Am J Physiol Endocrinol Metab. 2013 Mar 15;304(6):E651-60. doi: 10.1152/ajpendo.00471.2012. Epub 2013 Jan 22.
Sweet taste receptor subunits and α-gustducin found in enteroendocrine cells of the small intestine have been implicated in release of the incretin hormones glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) in response to glucose and noncaloric sweeteners. α-Gustducin has also been found in colon, although its function there is unclear. We examined expression of α-gustducin, GLP-1, and GIP throughout the intestine. The number of α-gustducin-expressing cells and those coexpressing α-gustducin together with GLP-1 and/or GIP increased from small intestine to colon. α-Gustducin also was coexpressed with fatty acid G protein-coupled receptor (GPR) 40, GPR41, GPR43, GPR119, GPR120, and bile acid G protein-coupled receptor TGR5 in enteroendocrine cells of the colon. In colon, GPR43 was coexpressed with GPR119 and GPR120, but not with TGR5. Treatment of colonic mucosa isolated from wild-type mice with acetate, butyrate, oleic acid, oleoylethanolamide, or lithocholic acid stimulated GLP-1 secretion. However, GLP-1 release in response to these fatty acids was impaired in colonic tissue from α-gustducin knockout mice.
在小肠的肠内分泌细胞中发现的甜味受体亚基和 α-味觉素与葡萄糖和无热量甜味剂刺激下肠降钙素相关肽 (GLP-1) 和葡萄糖依赖性胰岛素释放肽 (GIP) 的释放有关。α-味觉素也在结肠中发现,但它在那里的功能尚不清楚。我们检查了 α-味觉素、GLP-1 和 GIP 在整个肠道中的表达。表达 α-味觉素的细胞数量以及共同表达 α-味觉素与 GLP-1 和/或 GIP 的细胞数量从小肠增加到结肠。α-味觉素也与脂肪酸 G 蛋白偶联受体 (GPR) 40、GPR41、GPR43、GPR119、GPR120 和胆汁酸 G 蛋白偶联受体 TGR5 在结肠的肠内分泌细胞中共表达。在结肠中,GPR43 与 GPR119 和 GPR120 共表达,但与 TGR5 不共表达。用乙酸盐、丁酸盐、油酸、油酰乙醇酰胺或石胆酸处理来自野生型小鼠的结肠黏膜刺激 GLP-1 分泌。然而,这些脂肪酸对 GLP-1 的释放反应在 α-味觉素敲除小鼠的结肠组织中受损。