Patients with constipation-predominant irritable bowel syndrome (IBS) may have elevated serotonin concentrations in colonic mucosa as compared with diarrhea-predominant patients and subjects with normal bowel habits

Digestion. 2001;63(3):188-94. doi: 10.1159/000051888.


Background: Serotonin (5-HT) may play an important role in the regulation of colonic motility in humans. However, it is not known whether alterations in the colonic 5-HT system are involved in the pathophysiology of irritable bowel syndrome (IBS).

Methods: Colonic mucosal specimens ranging from the ascending colon to the rectum were obtained from patients with diarrhea- or constipation-predominant IBS (n = 7 and n = 8, respectively) and from subjects with normal bowel habits (n = 7) by endoscopic biopsy in order to determine whether patients with different clinical manifestations of IBS have different mucosal disposition of 5-HT. The tissue concentrations of 5-HT and its major metabolite, 5-hydroxyindoleacetic acid, were determined by reversed-phase high-performance liquid chromatography with fluorescence detection.

Results: In all study groups, the mean mucosal 5-HT concentrations obtained from the rectum were significantly (p < 0.05) higher than those obtained from more cephalic regions of the colon. In addition, the overall mean mucosal 5-HT concentrations obtained from patients with constipation-predominant IBS were significantly (p < 0.05) higher than those obtained from the control subjects and patients with diarrhea-predominant IBS. No significant differences were observed in 5-hydroxyindoleacetic acid concentrations among the three groups.

Conclusions: The mucosal 5-HT concentrations in the colon showed an ascending cephalocaudal gradient in all study groups. Although the mucosal 5-HT concentrations were elevated in patients with constipation-predominant IBS as compared with those with diarrhea-predominant IBS and the control subjects, further studies are necessary to determine whether the elevated mucosal 5-HT is a cause or a result of abnormal colonic motility.

Publication types

  • Clinical Trial
  • Comparative Study
  • Controlled Clinical Trial

MeSH terms

  • Adult
  • Aged
  • Analysis of Variance
  • Colonic Diseases, Functional / complications
  • Colonic Diseases, Functional / metabolism*
  • Constipation / complications
  • Constipation / diagnosis
  • Constipation / metabolism*
  • Diarrhea / complications
  • Diarrhea / diagnosis
  • Diarrhea / metabolism
  • Female
  • Humans
  • Intestinal Mucosa / metabolism*
  • Intestinal Mucosa / pathology
  • Male
  • Middle Aged
  • Probability
  • Sensitivity and Specificity
  • Serotonin / analysis*


  • Serotonin