Effects of Whole-Body γ-lrradiation on Lipid Peroxidation and Anti-oxidant Enzymes in the Liver of N-nitrosodiethylamine-treated Mice

B6C3F1 mice were treated per os with either normal saline or Af-nitrosodiethylamine (NDEA) (0.01, 0.1, 1.0 or 5.0 mg/kg body weight) daily for 21 days. On day 22 of the experiment, the animals were whole-body γ-irradiated (10 Gy) and examined at 3.5 days post-radiation exposure. Pretreatment of mice with NDEA at the lowest dosage (0.01 and 0.1 mg/kg) increased thiobarbituric acid-reactive substances (TBARS) and catalase (CAT) activity in the liver. Since the agent at the highest doses (1.0 and 5.0 mg/kg) did not have any effect(s) on TBARS, it was associated with the selective increase of thiol (SH) groups and GSH-linked antioxidant enzyme activities such as glutathione peroxidase (GPX), transferase (GST) and reductase (GR). γ-irradiation decreased TBARS and increased superoxide dismutase (SOD) and GPX activity in NDEAtreated mice. Simultaneously, γ-rays did not have any effect(s) on GST and GR enzymes, and it slightly decreased SH groups and CAT activity. Results of the present study indicate that NDEA can promote lipid peroxidation in mice liver, γ-irradiation of mice at a dose of 10 Gy modifes the activity of hepatic antioxidant enzymes, which in turn can lead to the reduction of NDEA-induced lipid peroxidation and/or prooxidant shift(s). The anti-oxidant enzymes such as SOD and GPX are suggested to be mainly involved in