Evaluation of the number of enterochromaffin cells and melatonin metabolism exponents in subjects with ulcerative colitis

Background:    Melatonin (MEL) is secreted in significant amounts by enterochromaffin (EC) cells in the gastrointestinal tract where it demonstrates enteroprotective effect. The amount of MEL secreted may depend on the number of EC cells and also on the activity of hydroxyindole-O-methyltransferase (HIOMT) – the enzyme conditioning its production.
        The aim of this study was to assess the number of EC cells and HIOMT expression in colonic mucosa and 6-hydroxymelatonin (6-HMS) urinary excretion in subjects with ulcerative colitis (UC).
    Material/Methods:    The investigations were performed in 56 patients with UC, aged 21–57 years, with mild (n=16), moderate (n=20) and severe (n=20) stage of this disease. The control group included 25 clinically healthy subjects (C). The number of EC cells was estimated in colonic mucosa (immunohistochemical method), HIOMT expression (RT-PCR method) and urine 6-HMS excretion (immunoenzymatic method).
    Results:    The number of EC cells in UC patients was 194.0±78.3 and in the control group 116.0±29.6 (p<0.001). HIOMT expression varied; in the mild stage it was similar to that in the controls and in the severe stage it was significantly lower –1.60±1.11 and 0.74±0.35, respectively (p<0.05). In the group with UC, urine 6-HMS excretion was also lower – 31.06 µg/24 h and 15.14±5.84 µg/24 h (p<0.001).
    Conclusions:    Melatonin secretion and metabolism are disturbed in subjects with UC. These changes depend on the severity of the disease and prove the participation of MEL in UC pathogenesis.

Keywords: Enterochromaffin Cells - metabolism, hydroxyindole-O-methyltransferase, ulcerative colitis, 6-hydroxymelatonin