title: Decreased expression of serotonin in the jejunum and increased numbers of mast cells in the terminal ileum in patients with irritable bowel syndrome.
abstract: OBJECTIVE
  To investigate if there are changes in serotonin (5-HT) levels, enterochromaffin (EC) cells and mast cells in small intestinal mucosa of patients with irritable bowel syndrome (IBS).
  
  
  METHODS
  Diarrhea-predominant (IBS-D, n = 20), or constipation-predominant (IBS-C, n = 18) IBS patients and healthy controls (n = 20) underwent colonoscopy and peroral small intestinal endoscopy, and mucosal samples were obtained at the descending part of the duodenum, proximal end of jejunum and terminal ileum. High-performance liquid chromatography-electrochemistry and immunohistochemical methods were used to detect 5-HT content, EC cells and mast cells.
  
  
  RESULTS
  (1) There were no differences in the number and distribution of EC cells between IBS patients and the normal group. (2) The mucosal 5-HT contents at the duodenum, jejunum and ileum in IBS-C patients were 182 +/- 90, 122 +/- 54, 61 +/- 35 ng/mg protein, respectively, which were all lower than those in the normal group (256 +/- 84, 188 +/- 91, and 93 +/- 45 ng/mg protein, respectively), with a significant difference at the jejunum (P < 0.05). There were no differences in the small intestinal mucosal 5-HT contents between IBS-D patients and the normal group. The mucosal 5-HT contents at the duodenum were significantly higher than those at the ileum in the three groups (P < 0.001). (3) The numbers of mast cells in patients with IBS-C and IBS-D at the ileum were 38.7 +/- 9.4 and 35.8 +/- 5.5/high power field (hpf), respectively, which were significantly more than that in the normal group (29.8 +/- 4.4/hpf) (P < 0.001). There was no significant difference in the numbers of mast cells at the other two parts between IBS patients and the normal group. The numbers of mast cells in IBS-C, IBS-D, and normal groups were all significantly higher at the ileum (38.7 +/- 9.4, 35.8 +/- 5.5, 29.8 +/- 4.4/hpf, respectively) than at the duodenum (19.6 +/- 4.7, 18.5 +/- 6.3, 19.2 +/- 3.3/hpf, respectively, P < 0.001).
  
  
  CONCLUSIONS
  The changes in the 5-HT signaling pathway at the jejunum of IBS-C patients and the increase in mast cells in patients with IBS at the terminal ileum may offer evidence to explain the pathogenesis of IBS.
authors.affiliation: Department of Gastroenterology, Second Hospital of Xi'an Jiaotong University, 157, Xi 5 Road, Xi'an 710004, Shaanxi Province, China.
authors.forename: Shen-Hao
authors.initials: SH
authors.lastname: Wang
authors.forename: Lei
authors.initials: L
authors.lastname: Dong
authors.forename: Jin-Yan
authors.initials: JY
authors.lastname: Luo
authors.forename: Jun
authors.initials: J
authors.lastname: Gong
authors.forename: Lu
authors.initials: L
authors.lastname: Li
authors.forename: Xiao-Lan
authors.initials: XL
authors.lastname: Lu
authors.forename: Shui-Ping
authors.initials: SP
authors.lastname: Han
mesh_terms: D000328:Adult; D000368:Aged; D004759:Enterochromaffin Cells; D005260:Female; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism* / Q000473:pathology; D007421:Intestine, Small / Q000378:metabolism* / Q000473:pathology; D043183:Irritable Bowel Syndrome / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008407:Mast Cells; D008875:Middle Aged; D012701:Serotonin / Q000378:metabolism*
chemical_list: D012701:Serotonin