Effects of selenium deficiency on biological results of X-ray and carbon-ion beam irradiation in mice.

The impact of radiation-induced hydrogen peroxide (HO) on the biological effects of X-rays and carbon-ion beams was investigated using a selenium-deficient (SeD) mouse model. Selenium is the active center of glutathione peroxidase (GSH-Px), and SeD mice lack the ability to degrade HO. Male and female SeD mice were prepared by feeding a torula yeast-based SeD diet and ultrapure water. Thirty-day survival rates after whole-body irradiation, radiation-induced leg contracture, and MRI-based redox imaging of the brain were assessed and compared between SeD and normal mice. Thirty-day lethality after whole-body 5.6 Gy irradiation with X-rays or carbon-ion beams was higher in the SeD mice than in the normal mice, while SeD did not give the notable difference between X-rays and carbon-ion beams. SeD also did not affect the maximum leg contracture level after irradiation with carbon-ion beams, but delayed the leg contraction rate. In addition, no marked effects of SeD were observed on variations in the redox status of the brain after irradiation. Collectively, the present results indicate that SeD slightly altered the biological effects of X-rays and/or carbon-ion beams. GSH-Px processes endogenous HO generated through mitochondrial respiration, but does not have the capacity to degrade HO produced by irradiation.