Abstract
Recently, we reported that radon inhalation activates antioxidative functions in some organs and inhibits oxidative damage such as carbon tetrachloride-induced hepatopathy. In this study, we examined the inhibitory effects of radon inhalation on carrageenan-induced inflammatory paw edema in mice using our new radon exposure system. Carrageenan was dissolved physiological saline solution (50μl of 1% v/v) and injected to the right hindpaw of female ICR mice (8 weeks old age). Prior to carrageenan injection, mice inhaled approximately 2000 Bq/m3 radon for 24 hours. In result, carrageenan injection induced paw edema, and inflammatory leukocytes were observed in paw. The tumor necrosis factor-alpha (TNF-α) and nitric oxide (NO) levels in serum significantly increased and superoxide dismutase (SOD) and catalase activities in paw significantly decreased following carrageenan injection. However, the relative increase in serum TNF-α levels of radon-treated mice were significantly smaller and the number of inflammatory leukocytes of radon-treated mice were significantly fewer than those of sham-treated mice. In addition, the relative decreases in paw SOD and catalase activities of radon-treated mice were significantly smaller than those of sham-treated mice. These findings suggested that radon inhalation activates antioxidative functions and inhibits carrageenan-induced inflammatory paw edema in mice. Our data show that radon therapy has a possibility for treating inflammation as a new indication.
