Distribution of 5-HT3, 5-HT4, and 5-HT7 Receptors Along the Human Colon.
- Author:
Nor S YAAKOB
1
;
Kenneth A CHINKWO
;
Navinisha CHETTY
;
Ian M COUPAR
;
Helen R IRVING
Author Information
- Publication Type:Original Article
- Keywords: Colon; G protein coupled receptor kinases; Ileum; Receptors, serotonin
- MeSH: Colon*; Colon, Sigmoid; DNA, Complementary; G-Protein-Coupled Receptor Kinases; Gastrointestinal Tract; Humans; Ileum; Intestines; Metabolism; Mucous Membrane; Polymerase Chain Reaction; Receptors, Serotonin; Receptors, Serotonin, 5-HT3; Receptors, Serotonin, 5-HT4; Reverse Transcription; RNA; Serotonin
- From:Journal of Neurogastroenterology and Motility 2015;21(3):361-369
- CountryRepublic of Korea
- Language:English
- Abstract: BACKGROUND/AIMS: Several disorders of the gastrointestinal tract are associated with abnormal serotonin (5-HT) signaling or metabolism where the 5-HT3 and 5-HT4 receptors are clinically relevant. The aim was to examine the distribution of 5-HT3, 5-HT4, and 5-HT7 receptors in the normal human colon and how this is associated with receptor interacting chaperone 3, G protein coupled receptor kinases, and protein LIN-7 homologs to extend previous observations limited to the sigmoid colon or the upper intestine. METHODS: Samples from ascending, transverse, descending, and sigmoid human colon were dissected into 3 separate layers (mucosa, longitudinal, and circular muscles) and ileum samples were dissected into mucosa and muscle layers (n = 20). Complementary DNA was synthesized by reverse transcription from extracted RNA and expression was determined by quantitative or end point polymerase chain reaction. RESULTS: The 5-HT3 receptor subunits were found in all tissues throughout the colon and ileum. The A subunit was detected in all samples and the C subunit was expressed at similar levels while the B subunit was expressed at lower levels and less frequently. The 5-HT3 receptor E subunit was mainly found in the mucosa layers. All splice variants of the 5-HT4 and 5-HT7 receptors were expressed throughout the colon although the 5-HT4 receptor d, g, and i variants were expressed less often. CONCLUSIONS: The major differences in 5-HT receptor distribution within the human colon are in relation to the mucosa and muscular tissue layers where the 5-HT3 receptor E subunit is predominantly found in the mucosal layer which may be of therapeutic relevance.
