HTR3A and irritable bowel syndrome: Before and after the treatment, the Visual Analogue Scale for Irritable Bowel Syndrome (VAS-IBS) was used to evaluate the gastrointestinal symptoms and mental well-being; and the expression of serotonin (5-hydroxytryptamine, 5-HT), 5-HT3 receptor (5-HT3R), and 5-HT4 receptor (5-HT4R) in sigmoid mucosal tissue were detected. Results.