Activation of biodefense system by low-dose irradiation or radon inhalation and its applicable possibility for treatment of diabetes and hepatopathy

Superoxide dismutase and glutathione peroxidase activities in a population exposed to high indoor radon concentration: a preliminary report

The objective of this study was to assess the effect of radon exposure on the modulation of endogenous antioxidants in a population chronically exposed to high levels of radon indoors. To do so, we measured the activities of superoxide dismutase (SOD) and glutathione peroxidase (GPX) in peripheral blood mononuclear cells (PBMCs) of people living in an area with high indoor radon concentration (Tande-Tande sub-village, Indonesia). The activities of SOD and GPX in Tande-Tande inhabitants were compared with those in subjects living in the Topoyo village (Indonesia), an area with low indoor radon levels. The activities of SOD and GPX in Tande-Tande sub-village inhabitants did not differ from those in people living in the Topoyo village (0.37 ± 0.021 versus 0.28 ± 0.018 U/mg protein and 8.46 ± 1.48 versus 8.34 ± 1.65 U/mg protein, p > .05). For both populations, there was a significant positive correlation between SOD and GPX activities (p < .001). No significant effects of gender, age, smoking habit, and body mass index on SOD and GPX activities were found for both groups. Although no significant modulation of SOD and GPX activities in PBMCs was detected, further studies should expand the sample size and also assess antioxidant levels in the serum. This study provides a first picture of endogenous antioxidant systems in Tande-Tande sub-village inhabitants, but a more comprehensive analysis, including the measurement of catalase (CAT) activity, might provide additional insight into the effects of chronic exposure to high indoor radon concentrations.

Comparative study on the inhibitory effects of α-tocopherol and radon on carbon tetrachloride-induced renal damage

Since the 2011 nuclear accident in Fukushima, the effects of low-dose irradiation, especially internal exposure, are at the forefront of everyone's attention. However, low-dose radiation induced various stimulating effects such as activation of antioxidative and immune functions. In this study, we attempted to evaluate the quantitative effects of the activation of antioxidative activities in kidney induced by radon inhalation on carbon tetrachloride (CCl4)-induced renal damage. Mice were subjected to intraperitoneal (i.p.) injection of CCl4 after inhaling approximately 1000 or 2000 Bq/m3 radon for 24 h, or immediately after i.p. injection of α-tocopherol (100, 300, or 500 mg/kg bodyweight). In case of renal function, radon inhalation at a concentration of 2000 Bq/m3 has the inhibitory effects similar to α-tocopherol treatment at a dose of 300-500 mg/kg bodyweight. The activities of superoxide dismutase and catalase in kidneys were significantly higher in mice exposed to radon as compared to mice treated with CCl4 alone. These findings suggest that radon inhalation has an antioxidative effect against CCl4-induced renal damage similar to the antioxidative effects of α-tocopherol due to induction of antioxidative functions.

Inhibitory effects of pretreatment with radon on acute alcohol-induced hepatopathy in mice

We previously reported that radon inhalation activates antioxidative functions in the liver and inhibits carbon tetrachloride-induced hepatopathy in mice. In addition, it has been reported that reactive oxygen species contribute to alcohol-induced hepatopathy. In this study, we examined the inhibitory effects of radon inhalation on acute alcohol-induced hepatopathy in mice. C57BL/6J mice were subjected to intraperitoneal injection of 50% alcohol (5 g/kg bodyweight) after inhaling approximately 4000 Bq/m³ radon for 24 h. Alcohol administration significantly increased the activities of glutamic oxaloacetic transaminase (GOT), glutamic pyruvic transaminase (GPT) in serum, and the levels of triglyceride and lipid peroxide in the liver, suggesting acute alcohol-induced hepatopathy. Radon inhalation activated antioxidative functions in the liver. Furthermore, pretreatment with radon inhibited the depression of hepatic functions and antioxidative functions. These findings suggested that radon inhalation activated antioxidative functions in the liver and inhibited acute alcohol-induced hepatopathy in mice.

Comparative study on the inhibitory effects of antioxidant vitamins and radon on carbon tetrachloride-induced hepatopathy

We have previously reported that radon inhalation activates anti-oxidative functions and inhibits carbon tetrachloride (CCl(4))-induced hepatopathy. It has also been reported that antioxidant vitamins can inhibit CCl(4)-induced hepatopathy. In the current study, we examined the comparative efficacy of treatment with radon, ascorbic acid and α-tocopherol on CCl(4)-induced hepatopathy. Mice were subjected to intraperitoneal injection of CCl(4) after inhaling approximately 1000 or 2000 Bq/m(3) radon for 24 h, or immediately after intraperitoneal injection of ascorbic acid (100, 300, or 500 mg/kg bodyweight) or α-tocopherol (100, 300, or 500 mg/kg bodyweight). We estimated the inhibitory effects on CCl(4)-induced hepatopathy based on hepatic function-associated parameters, oxidative damage-associated parameters and histological changes. The results revealed that the therapeutic effects of radon inhalation were almost equivalent to treatment with ascorbic acid at a dose of 500 mg/kg or α-tocopherol at a dose of 300 mg/kg. The activities of superoxide dismutase, catalase, and glutathione peroxidase in the liver were significantly higher in mice exposed to radon than in mice treated with CCl(4) alone. These findings suggest that radon inhalation has an anti-oxidative effect against CCl(4)-induced hepatopathy similar to the anti-oxidative effects of ascorbic acid or α-tocopherol due to the induction of anti-oxidative functions.