Radiomitigation by Melatonin in C57BL/6 Mice: Possible Implications as Adjuvant in Radiotherapy and Chemotherapy

Background/Aim: Melatonin (N-acetyl-5-met hoxytryptamine), a chief secretory molecule of the pineal gland, has multiple properties, and numerous clinical investigations regarding its actions are in progress. This study investigated the radiomitigative role of melatonin in C57BL/6 mice. Materials and Methods: Melatonin (100 mg/kg) was orally administered once daily starting at 1 h on day 1 and subsequently every 24 h until day 7 after whole-body irradiation (WBI) and survival was monitored for 30 days. The bone marrow, spleen, and intestine were studied to evaluate the mitigative potential of melatonin after radiation-induced damage. Results: Melatonin significantly improved the survival upto 60% and 90% after 9 Gy (lethal) and 7.5 Gy (sub-lethal) WBI, respectively. Melatonin alleviated WBI-induced myelosuppression and pancytopenia, and increased white blood cell, red blood cell, platelet, and lymphocyte (CD4(+) and CD8(+)) counts in peripheral blood. Bone marrow and spleen cellularity were restored through enhanced haematopoiesis. Melatonin ameliorated the damage in the small intestine, and promoted recovery of villi length, crypts number, and goblet cell count. Conclusion: Melatonin mitigates the radiation-induced injury in the gastrointestinal and haematopoietic systems. The observed radiomitigative properties of melatonin can also be useful in the context of adjuvant therapy for cancer and radiotherapy.