Serotonin synthesis and uptake in symptomatic patients with Crohn's disease in remission

Clin Gastroenterol Hepatol. 2007 Jun;5(6):714-20. doi: 10.1016/j.cgh.2007.02.013. Epub 2007 May 4.


Background & aims: Symptoms resembling irritable bowel syndrome (IBS) are reported frequently in Crohn's disease (CD) patients in remission. Studies of the mucosal content of serotonin, which is a pivotal neurotransmitter in the gut, suggest that serotonin availability is altered in IBS patients. We aimed to study the role of serotonin in the generation of IBS-like symptoms in CD patients in remission.

Methods: Ileal and colonic biopsy specimens were obtained from 20 CD patients in remission, 10 with and 10 without IBS-like symptoms, and 11 healthy controls. Enterochromaffin cells were counted, and messenger RNA expression levels of tryptophan hydroxylase (TpH)-1 and serotonin reuptake transporter were determined.

Results: The levels of mucosal serotonin reuptake transporter expression were significantly higher in the ileum than in the colon, in all groups studied (P < .02). When the ileum and colon were analyzed separately, TpH-1 expression in the colon of CD patients with IBS-like symptoms was found to be significantly higher compared with the 2 other studied groups (controls, P < .005; CD patients without IBS-like symptoms, P < .01). The number of enterochromaffin cells per gland was comparable for the patient groups in the ileum and colon.

Conclusions: CD patients in remission who experience IBS-like symptoms have increased mucosal TpH-1 levels in the colon, suggesting that increased serotonin biosynthesis in the colon plays a role in the generation of the symptoms.

MeSH terms

  • Adult
  • Cell Count
  • Colon / pathology
  • Colonoscopy
  • Crohn Disease / metabolism*
  • Enterochromaffin Cells / cytology
  • Enteroendocrine Cells / cytology
  • Female
  • Humans
  • Ileum / pathology
  • Irritable Bowel Syndrome / metabolism
  • Male
  • RNA, Messenger / metabolism
  • Remission Induction
  • Serotonin / biosynthesis*
  • Serotonin / metabolism
  • Serotonin Plasma Membrane Transport Proteins / metabolism
  • Tryptophan Hydroxylase / metabolism


  • RNA, Messenger
  • Serotonin Plasma Membrane Transport Proteins
  • Serotonin
  • Tryptophan Hydroxylase