RESUMO
INTRODUCTION: Short bowel syndrome (SBS) is a clinical condition resulting from the loss of absorptive surface area following resection of 50% or more small bowel. Morphological and functional changes called "intestinal adaptation" occur in the residual intestine. Melatonin exists in the gastrointestinal tract and has effect on mitotic activity. Therefore, we hypothesized that melatonin may have beneficial effects on intestinal adaptation. MATERIALS AND METHODS: A total of 32 male Wistar albino male rats were divided into four groups. In group I (sham-S), small bowel was transected and reanastomosed. In group II (SBS-control), 75% small bowel resection and anastomosis were performed. In group III (SBS-vehicle), after 75% small bowel resection and anastomosis, 2 mL of 5% ethanol in saline was given intraperitoneally once a day. In group IV (SBS-melatonin), after 75% small bowel resection and anastomosis, 300 µg/kg melatonin was given intraperitoneally once a day. After 15 days, small bowels were removed and divided into two segments as jejunum and ileum. Each segment was weight and measured. Histological examination was performed in all samples. Bowel and mucosal weights and DNA/protein ratio were calculated. Apoptotic cells were also identified. RESULTS: The bowel length measurements were statistically longer in group IV. Mucosal and bowel weights were the highest in group IV. The villus height, crypt depth, and the number of mitotic figures were the highest in the jejunum of group IV. Melatonin also gave rise to a significant increase in DNA/protein ratios in group IV. CONCLUSION: According to this study, melatonin significantly enhanced intestinal adaptation.