Low dose gamma-irradiation differentially modulates antioxidant defense in liver and lungs of Balb/c mice

Purpose: To evaluate the effect of low-dose (<50 cGy) whole body gamma-irradiation on the antioxidant defense system in the liver and the lungs of mice at various post-irradiation intervals. Materials and methods: Male Balb/c mice, 5 - 6 weeks of age, were divided into irradiated and non-irradiated groups. Whole body irradiation was done with gamma-rays from a Co-60 source at doses of 10, 25 and 50 cGy (48.78 cGy/min). Lipid peroxidation and antioxidant status were measured in the liver and the lungs at 4, 12 and 24 h after irradiation. Results: Lipid peroxidation increased by 1.38 and 2.0 fold in lung and liver respectively at 12 h after exposure to 25 cGy. Whole body exposure to 25 and 50 cGy significantly (p<0.05) increased the hepatic reduced glutathione at 4 h. Reduced glutathione continued to rise until 12 h and returned to the basal level at 24 h, whereas in the lungs it remained elevated until 24 h at 10 and 25 cGy. Antioxidant enzymes activities for superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase increased by 1.22, 1.13, 1.22 and 1.11 fold respectively (p<0.05) in the liver at 4 h after exposure to 50 cGy and remained elevated at almost the same level up to 12 h after exposure. Surprisingly these antioxidant defense enzymes remained unaltered in the lung at the above radiation doses. Conclusions: Low-dose whole body gamma-irradiation differentially modulates the antioxidant defense system in the liver and lungs of mice. The induction of endogenous glutathione, immediately after exposure to low-dose gamma-irradiation, may be beneficial in protecting the cells from reactive oxygen species (ROS) induced oxidative stress.