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Keywords:

  • Serotonin;
  • enterochromaffin;
  • constipation;
  • diarrhoea;
  • colonic inertia;
  • neurotransmitters

Abstract

Aim To evaluate differences in distribution, density and staining intensity of enterochromaffin cells (EC) and serotonin cells (SC) in the colonic mucosa of patients with colonic inertia (CI), idiopathic diarrhoea (ID) and a control group.

Methods Three groups were studied: 19 patients' colons after subtotal colectomy for CI, and 17 patients' biopsies for diarrhoea (>3 bowel movements/day) with histological findings of normal mucosa (excluding microscopic, eosinophillic and collagenous colitis). The third group included 15 patients who underwent colonoscopy and biopsy for indications other than constipation, inflammatory bowel disease, diarrhoea or neoplasm (control group). Specimen blocks were obtained in each case from the right and left colon. Immunohistochemical staining for EC and SC were done on 4 µm sections from Hollandes fixed, paraffin embedded tissues with primary rabbit antibody against chromagranin A or serotonin, and biotynylated secondary antibody and enzyme labelled streptavidin.

Results The number of EC in the mucosa of the left colon in patients with CI (16.8 ± 10.2) and ID (19.9 ± 9.7) were significantly higher than they were on the right side (CI: 9.4 ± 6.0, ID: 12.1 ± 5.3). However, there were no significant differences between the left and right sides in the control group (L: 10.3 ± 5.3; R: 13.4 ± 7.6). Although the quantity of EC in the left colon in both patients with CI (P < 0.05) and ID (P < 0.01) were significantly higher than in the controls, there was no significant difference between CI and ID. In both the right and left colon, the percentage of EC with low positive density was significantly higher (P < 0.01) while those cells with moderate or low staining intensity were significantly lower in patients with CI than in either patients with ID or control group. In patients with CI, the quantity of SC in the mucosa of the left colon (12.1 ± 6.4) was higher than in the right (CI: 7.9 ± 3.6; control 4.6 ± 3.3; ID 4.6 ± 2.9) (P = 0.0057). In contrast there was no significant difference in SC in either the ID or control groups. The quantity of SC in both sides of the colon was significantly higher both in patients with CI as compared to the control group (P < 0.01) and patients with CI vs. patients with ID (L = P < 0.01; R = P < 0.05). There was a significantly positive correlation between the numbers of EC and SC in patients with CI (L: r = 0.5425, P < 0.05; R: r = 0.745, P < 0.01).

Conclusion In patients with CI, EC increases possibly due to an increase in SC. Conversely, in patients with ID, the EC increase results from peptides other than SC. Our results suggest that different aetiological factors contribute to ID and CI.