HTR3A and irritable bowel syndrome: Obtained findings with a postinflammatory IBS rat model showed visceral hypersensitivity accompanied by fecal microbial dysbiosis, elevated serum 5-HT level, the upregulated expression of colonic 5-HT3A/5-HT2B receptors, and impaired tight-junction protein expression, while the administration of a 5-HT3A receptor antagonist or FMT from the feces of normal healthy rats alleviated the IBS-like symptoms [168].