Effect of Melatonin on Bone Mineral Density of Irradiated Rats

Objective: Melatonin is a powerful endogenous antioxidant and it may play a role in preventionof radiation-induced damage. The aim of this study was to investigate the effect ofmelatonin on bone mineral density in rats receiving radiation.Materials and Methods: Sprague Dawley rats were divided into four groups. Group 1(control group) received neither melatonin nor radiation (control group). Group 2 (Melgroup) was administered intraperitoneal injections of 5mg/kg melatonin daily for ten days.Group 3 (RT group) and Group 4 were exposed to total cranium radiation of 5 Gy in a singledose by using a cobalt-60 teletherapy unit. In addition to irradiation, group 4 (RT + Melgroup) was administered 5mg/kg of melatonin intraperitoneally. At the end of the 10th day,the rats' cranium and vertebrae bone mineral densities (BMDs) were measured.Results: When cranial BMDs were evaluated, statistically more significant BMD increaseswere seen in the Mel group and the RT + Mel groups than in the control group. No significantdifference was seen in the Mel group versus the RT + Mel group; however, there wasa significant difference between RT and RT + Mel groups. When vertebral BMDs wereevaluated, the only significant difference was found between the control and Mel groups.Conclusion: We think that melatonin is a radioprotective agent. However, we would liketo emphasize that further studies are needed before clinical trials with melatonin are initiated.