臨牀消化器内科 Vol.28 No.6(7)


特集名 栄養代謝制御における消化管生理活性ペプチドの役割
題名 アミノ酸のインクレチン分泌制御機能 ― 消化管化学センサーの機序と栄養代謝制御における役割について
発刊年月 2013年 06月
著者 保坂 浩子 群馬大学大学院病態制御内科
著者 草野 元康 群馬大学医学部附属病院光学医療診療部
著者 川田 晃世 群馬大学大学院病態制御内科
著者 栗林 志行 群馬大学大学院病態制御内科
著者 下山 康之 群馬大学大学院病態制御内科
著者 河村 修 群馬大学大学院病態制御内科
【 要旨 】 食べたものが有用なものか,有害なものかを消化管が感知することは,その後の消化吸収のプロセスに備えたり,嘔吐や胃排出遅延などの防御反応を引き起こすのに必須である.栄養素感知の仕組みとして,栄養素の吸収によるもののほか,腸管細胞表面の栄養素特異的受容体による感知があり,とくにGタンパク質共役受容体(G protein-coupled receptor;GPCR)が重要である.グルタミン酸は食事性の蛋白質にもっとも多く含まれるアミノ酸である.L体のアミノ酸はラットのGLP(glucagon-like peptide)-1分泌細胞からGLP-1分泌を引き起こすことが報告されている.われわれの実験では流動食にグルタミン酸ナトリウムを添加することにより食後早期のGLP-1分泌が促進され,食後血糖の上昇を抑える効果が認められた.
Theme The Roles of Gut Physiological Active Peptides in the Control of Nutrition and Metabolism
Title Effect of Amino Acids on Incretin Secretion
Author Hiroko Hosaka Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine
Author Motoyasu Kusano Department of Endoscopy and Endoscopic Surgery, Gunma University Hospital
Author Akiyo Kawada Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine
Author Shiko Kuribayashi Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine
Author Yasuyuki Shimoyama Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine
Author Osamu Kawamura Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine
[ Summary ] After ingestion of a meal, a large variety of physiological reactions occur outside and within the gastrointestinal tract. Recently, the field of nutrient sensing in the gastrointestinal tract has evolved rapidly examining the deorphanization of previously unliganded G-protein-coupled receptors, which respond to important nutrients. One mechanism for the detection of nutrients is linked to nutrient absorption and processing by enterocytes. Another mechanism relates to the occurrence of nutrient-specific receptors on enterocyte luminal cell membranes. Unlike carbohydrates and fats, protein degradation in the digestive process generates a complex mixture of breakdown products, ranging from large oligopeptides to a mixture of individual amino acids. Single L-amino acids, including L-glutamate, increase GLP-1 release from cultured enteroendocrine-like GLUTag cells. We investigated the effects of monosodium L-glutamate (MSG) on glucose homeostasis, incretin secretion and gastric emptying in humans after a liquid meal. MSG stimulated GLP-1 secretion and improved early postprandial glycemia. This effect was not associated with a change in gastric emptying, but is possibly related to stimulation of GLP-1 secretion.
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