Despite the therapeutic effects of radiotherapy on tumor cells, it has potential severe adverse effects on the surrounding normal tissues. Acute or chronic intestinal adverse effects that are likely to occur in patients undergoing radiotherapy for pelvic and abdominal cancers lead to increased morbidity, significant impairment of the quality of life, and economic losses. Various biological, chemical and pharmacological agents are being tested to protect from and to treat radiation enteritis. This experimental study aimed to investigate the protective effects of melatonin against radiation-induced intestinal injury when administered before radiation exposure in rats.In the present study, villus height and the number of villi in the ileum and jejunum of rats receiving two different doses of intraperitoneal melatonin (5 and 10 mg/kg) prior to a single fraction of radiation given at a dose of 8 Gy to the abdominal region, was evaluated by histopathological examination 3 and 7 days after radiation exposure.At a dose of 5 mg/kg, melatonin was found to be effective in preventing radiation-induced injury to villus height in the jejunum and the number of villi in the ileum and jejunum, and at a dose of 10 mg/kg it was also effective in preventing radiation-induced injury to villus height in the ileum.Melatonin is effective for the prevention of radiation-induced intestinal injury. This outcome can be considered an evidence to test melatonin in clinical trials.
