Analysis of serotonin in intestinal mucosa and tryptophan availability in relation to canine inflammatory bowel disease

2017 Fiscal Year Final Research Report

• Project/Area Number: 26450424
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Veterinary medical science
• Research Institution: Tokyo University of Agriculture and Technology
• Principal Investigator: Ide Kaori 東京農工大学, (連合)農学研究科(研究院), 講師 (40550281)
• Project Period (FY): 2014-04-01 – 2018-03-31
• Keywords: セロトニン / トリプトファン / 犬炎症性腸疾患 / IDO1

Outline of Final Research Achievements

Changes in intestinal serotonin (5-HT) system is an important character involving in both Irritable bowel syndrome and Inflammatory bowel disease (IBD) in humans. Authors previously found that serotonin-producing cells in intestinal tissue was increased in IBD dogs, and that transcription levels of genes coding enzyme to produce 5-HT and genes coding factor associated with 5-HT elimination showed different pattern in canine IBD cases.
This study was focused on tryptophan, a precursor to the 5-HT, and its metabolic pathway, and their relations with canine IBD pathophysiology was analyzed. Most important result was that in more than a third of IBD cases, mRNA level of IDO1, an enzyme which metabolize tryptophan and which is known to indirectly act towards anti-inflammatory, was high, which is consistent observation with humans. Moreover, correlations of IDO1 mRNA level with severity of hypoalbuminemia and high histopathologic score was observed.

Free Research Field

獣医内科学

Academic Significance and Societal Importance of the Research Achievements

慢性腸炎は犬で最も多い消化器疾患の一つであり，病理組織学的な検索のほか炎症細胞や炎症性サイトカイン，腸内細菌叢との関連など多方向から病態解析が行われている。一方，医学では難治性の腸炎である炎症性腸疾患およびより罹患者数が多い過敏性腸症候群が互いにオーバーラップする部分であるセロトニン機構の異常や，炎症を沈静化する機構と考えられているIDO1経路の変化も腸炎の重要な病態として近年注目されている。本研究は初めてこれらの観点に立った犬の腸炎の基礎的研究であり，得られた知見は犬の慢性腸炎の理解をさらに深める糸口となるほか，一部はトランスレーショナルリサーチとして医学への情報提供にもなる。