Enhancement of antioxidant function in various organs in mice using combined thermal and radon inhalation treatment.

Enhancing antioxidant function is a key strategy for preventing and treating oxidative stress-related diseases. Radon inhalation and thermal treatment (TT) increase the levels of antioxidant enzymes, such as superoxide dismutase (SOD). The positive effects of this combination on pain-related diseases have been reported; however, few studies have elucidated the underlying mechanisms. In this study, we examined the enhancement of antioxidant function in various organs of mice subjected to combined TT and radon inhalation. The mice were placed in an incubator once daily for 40 min at 38.5 ± 0.5°C and treated for 1, 3 and 7 days. The mice then inhaled radon at a concentration of 2000 Bq/m3 for 24 h. The characteristic changes in antioxidant function following combined TT and radon inhalation could be categorized into four groups: (i) increased antioxidant function in the brain and colon; (ii) increased or decreased antioxidant function, as observed in the kidney; (iii) decreased antioxidant function, such as in the lungs and (iv) no changes, such as in the small intestine, spleen, pancreas, heart, liver and stomach. Additionally, SOD may be the antioxidant enzyme most sensitive to combined TT and radon treatment. Collectively, the combined treatment may be the most effective in activating antioxidative functions in the brain and colon. This study provides new insights into the effects of combined TT and radon inhalation.