Role of serotonin in the pathophysiology of the irritable bowel syndrome


Mayo Clinic Scottsdale, Gastroenterology and Hepatology, 13400 E Shea Blvd., Scottsdale, AZ 85259, U.S.A. E-mail:


The irritable bowel syndrome (IBS) is a complex disorder that is associated with altered gastrointestinal motility, secretion, and sensation. Serotonin (5-HT) is an important neurotransmitter and paracrine signalling molecule in the gastrointestinal tract. 5-HT release from enterochromaffin (EC) cells initiates peristaltic, secretory, vasodilatory, vagal and nociceptive reflexes. The enteric nervous system (ENS) comprises a semiautonomous effector system that is connected to the central autonomic network. Parasympathetic and sympathetic nerves modulate the ENS via afferent and efferent communications. Ongoing, bidirectional brain–gut interactions involving 5-HT pathways occur that significantly influence the effector systems. Altered 5-HT signalling may lead to both intestinal and extraintestinal symptoms in IBS. 5-HT directly and indirectly affects intestinal motor and secretory function and abnormalities may lead to either constipation or diarrhea. 5-HT modulates sensation and perception of visceral stimulation at peripheral and central sites. Therapeutic agents targeting altered 5-HT signalling may provide new, effective treatments for patients with IBS.

British Journal of Pharmacology (2004) 141, 1285–1293. doi:10.1038/sj.bjp.0705762