Room: ePoster Forums
Purpose: During radiotherapy for abdominal malignancies, the colon tissues may be exposed to high doses of radiation, which could lead to inflammation, pain, ulcer, bleeding and gastrointestinal disorders. Therefore, in present study, we aimed to evaluate the radioprotective effect of melatonin against ionizing radiation-induced toxicity in colon.
Methods: Twenty male Wistar rats were randomly assigned to four groups of five members, as follows: group I (control, without radiation or melatonin treatment), group II (radiation only), group III (100 mg/kg melatonin only) and group IV (100 mg/kg melatonin + radiation). Groups II and IV rats received 8 Gy single radiation dose from a cobalt-60 gamma ray source to their abdominal regions. Intraperitoneal administration of melatonin to groups III and IV rats was done 30 min before irradiation. All animals were euthanized 5 days after irradiation. Subsequently, their colon tissues were carefully detached and examined biochemically for the following parameters: malondialdehyde (MDA), catalase (CAT) and superoxide dismutase (SOD).
Results: Biochemical assessment of ratsâ€™ colon tissues showed that melatonin administration prior to irradiation significantly increased the CAT and SOD levels compared to the radiation group (43.48 Â± 3.07 vs. 38.72 Â± 1.03 U/g protein, and 47.08 Â± 1.86 vs. 37.52 Â± 3.76 U/g protein, respectively, P < 0.05). Furthermore, the MDA levels in the melatonin + radiation group was significantly reduced compared to radiation group (14.88 Â± 0.25 vs. 17.92 Â± 1.14 nmol/g protein, P < 0.05). There were no significant differences between the melatonin + radiation group and control group (P > 0.05) for all biochemical evaluations.
Conclusion: The administration of melatonin before irradiation prevented radiation-induced toxic effects to the colon by increasing both SOD and CAT levels, in addition to decreasing the MDA levels. Hence, we propose the use of melatonin as an effective radioprotector for the colon.