Effects of thoron inhalation and cyclosporin A treatment on dextran sulfate sodium-induced oxidative damage in mice

Tanaka, Ayumi*; Naoe, Shota*; Takenaka, Reiju*; Kanzaki, Norie   ; Sakoda, Akihiro   ; Yamaoka, Kiyonori*; Kataoka, Takahiro*

Radon (Rn) or thoron (Rn, Tn) inhalation enhances the antioxidant activity in some organs. However, the effects of thoron on the colon have not been reported. This study aimed to clarify the effects of thoron inhalation, alone and in combination with Cyclosporin A (CsA), on oxidative stress and colitis induced by dextran sulfate sodium (DSS) in mice. The mice were subjected to 8-day thoron inhalation (c-Tn) or thoron inhalation every other day (f-Tn) at a concentration of 500 Bq/m. The mice were then administered a combination of 3% DSS and CsA or vehicle for 7 d. Although the disease activity index (DAI) reduced significantly by day 2 in the c-Tn group, the score was significantly higher than that in the f-Tn group. Superoxide dismutase activity in the colons of both the c-Tn and f-Tn group mice and catalase activity in the c-Tn group mice were significantly higher than those in the sham groups. These observations suggest that DSS-induced colitis was effectively inhibited in the earlier stages by the c-Tn mode of inhalation than by the f-Tn mode. This could be attributed to the activation of antioxidant functions by c-Tn inhalation. Furthermore, thoron inhalation and CsA treatment showed no combined effects.