Organoids as an ex vivo model for studying the serotonin system in the murine small intestine and colon epithelium.
Intestinal organoids were recently established as an ex vivo model of the intestinal epithelium. The present study investigated the serotonin (5-hydroxytryptamine, 5-HT) system using organoids. Organoids from murine small intestinal and colonic crypts were successfully cultured. Reverse transcription-polymerase chain reaction (RT-PCR) analysis showed that small intestinal and colonic organoids express mRNAs encoding tryptophan hydroxylase-1 (TPH1) (the rate-limiting enzyme of 5-HT synthesis), serotonin reuptake transporter (SERT), 5-HT receptor (HTR)2A, HTR2B, and HTR4. SERT mRNA levels were significantly higher in the small intestine than in the colon in both the mucosal tissues and organoids, as estimated by quantitative real-time RT-PCR. Although the 5-HT concentration and levels of chromogranin A (CgA) (an enteroendocrine cell marker), TPH1, and HTR4 mRNAs were significantly higher in the colonic mucosa than the small intestinal mucosa, they were the same in small intestinal and colonic organoids. There were no significant differences in HTR2A and HTR2B mRNA levels between the small intestine and colon in either the mucosal tissues or organoids. Immunofluorescence staining showed that the number of CgA-positive cells in the colonic organoids appeared to increase upon culturing with acetate. Acetate supplementation significantly increased CgA, TPH1, and HTR4 mRNA levels in the colonic organoids. We propose that organoids are useful for investigating the 5-HT system in the intestinal epithelium, even though colonic organoids may require gut microbiota-derived factors such as short-chain fatty acids.
Graduate School of Environmental and Life Science, Okayama University, Okayama 700-8530, Japan.
Takeshi
T
Tsuruta
Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan.
Shinichi
S
Saito
Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan.
Yosuke
Y
Osaki
Graduate School of Life Science, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan.
Akihiro
A
Hamada
Graduate School of Agricultural and Life Sciences, The University of Tokyo, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Ayako
A
Aoki-Yoshida
Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido 060-8589, Japan. Electronic address: ksnym@chem.agr.hokudai.ac.jp.
Kei
K
Sonoyama
D000818:Animals; D002478:Cells, Cultured; D003106:Colon / Q000378:metabolism*; D005260:Female; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D023421:Models, Animal; D009924:Organ Culture Techniques / Q000379:methods*; D009940:Organoids / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*
D012701:Serotonin
Enterochromaffin cell; Intestinal organoid; Serotonin; Short-chain fatty acid