ABSTRACT
Melatonin is a powerful endogenous antioxidant and it may play a role in prevention of radiation-induced damage. The aim of this study was to investigate the effect of melatonin on bone mineral density in rats receiving radiation. Sprague Dawley rats were divided into four groups. Group 1 [control group] received neither melatonin nor radiation [control group]. Group 2 [Mel group] 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 single dose by using a cobalt-60 teletherapy unit. In addition to irradiation, group 4 [RT + Mel group] 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. When cranial BMDs were evaluated, statistically more significant BMD increases were seen in the Mel group and the RT + Mel groups than in the control group. No significant difference was seen in the Mel group versus the RT + Mel group; however, there was a significant difference between RT and RT + Mel groups. When vertebral BMDs were evaluated, the only significant difference was found between the control and Mel groups. We think that melatonin is a radioprotective agent. However, we would like to emphasize that further studies are needed before clinical trials with melatonin are initiated