SLC6A4 and irritable bowel syndrome: Therefore, in this study, an IBS model was constructed through the transplantation of fecal bacteria before assessing the number of 2-h fecal pellets, fecal water content, gastrointestinal transit time, small intestinal propulsion rate, levels of inflammatory factors, histopathological changes, the 5-HT and serotonin transporter (SERT) content in colon and brain tissues, as well as the gut microbiota composition and metabolites.