The mechanisms whereby heat-killed lactic acid bacteria up-regulates gut-derived serotonin synthesis and promotes defecation

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05921
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 38050:Food sciences-related
• Research Institution: Niigata University
• Principal Investigator: Hara Takashi 新潟大学, 自然科学系, 准教授 (20323959)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 乳酸菌 / 排便促進 / セロトニン

Outline of Final Research Achievements

We demonstrated the contribution of intestinal serotonin (5-HT) in improving bowel movement by ingesting heat-killed lactic acid bacteria. Mice received p-chlorphenylalanine to block intestinal 5-HT production showed reduced 5-HT positive cells in the intestinal tract and prolonged intestinal transit time, these changes were restored by ingestion of heat-killed Lactobacillus casei subsp. casei 327 (Lc327). Heat-killed Lc327 also improved bowel movements in a mouse model of constipation, with increased 5-HT positive cells, increased TPH1 expression, reduced SERT and iNOS expression, increased butyrate levels and an increase in the number of interstitial cells of Cajal in the intestinal tract.

Free Research Field

食品機能学

Academic Significance and Societal Importance of the Research Achievements

乳酸菌は便通改善効果を示すことがよく知られているが、その作用機構はよくわかっていない。本研究において、乳酸菌死菌体の便通改善効果に腸管5-HTが関与することを腸管5-HT産生を遮断したマウスで実証した。乳酸菌死菌体は便秘モデルマウスに対しても便通改善作用を示し、大腸における5-HT陽性細胞の増加、5-HT再取り込みトランスポーターの抑制など、5-HTの働きが関わる証拠が得られると同時に腸管グリア細胞やカハール介在細胞など、腸運動の制御に重要な役割を果たす細胞に影響を及ぼす可能性が示された。