Antioxidant enzymes activity and lipid peroxidation in liver and kidney of rats exposed to cadmium and ethanol.

The oxidative status of liver and kidney of rats co-exposed to cadmium (50 mg Cd/l in drinking water) and ethanol (5 g EtOH/kg body weight/24 h, intragastrically) for 12 weeks was studied. The activities of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) as well as the concentration of malondialdehyde (MDA), as an indicator of lipid peroxidation, were measured in homogenates of the liver and kidney. Concentrations of zinc (Zn), copper (Cu), iron (Fe) and Cd in the serum or blood, and their content in the liver and kidney as well as EtOH concentration in the whole blood were assayed. Daily Cd intake in the Cd and Cd+EtOH groups was similar and ranged from 2.39 to 4.88 mg/kg body weight/24 h and from 2.64 to 4.14 mg/kg body weight/24 h, respectively. After the administration of EtOH alone, the activity of SOD increased in the kidney and decreased in the liver, whereas the activity of CAT decreased in both these organs, and MDA concentration increased in the liver and was unchanged in the kidney. The exposure to 50 mg Cd/l led to a decrease in the activities of SOD in the liver and CAT in the liver and kidney, and an increase in the kidney activity of SOD and MDA concentration in both these organs. In the rats co-exposed to Cd and EtOH, the kidney activity of SOD and the liver concentration of MDA were lower, whereas the kidney activity of CAT was higher compared to the Cd group. The concentration of Fe in the serum and its content in the liver of rats treated with EtOH increased, whereas the concentrations of Zn and Cu in the serum and the content of Zn, Cu and Fe in the kidney and that of Zn and Cu in the liver were unchanged. In the liver and kidney of rats treated with Cd alone, the content of Fe was decreased and that of Zn and Cu was enhanced. After EtOH administration to Cd-exposed rats, a decrease in Cu serum concentration and its liver content and an increase in Fe concentration in the serum and its content in the liver and kidney, compared to the group exposed to Cd alone, were noted. Moreover, EtOH decreased the blood Cd concentration and its accumulation in the liver and kidney of these animals. EtOH alone decreased Cd content in the liver and increased in the kidney, however the whole content of Cd in these organs was unchanged compared with control. The results of this study indicate that despite the ability of Cd and EtOH to induce the oxidative stress the effect in the liver and kidney is not intensified at simultaneous exposure to both substances. The changes in the studied indicators of oxidative stress (SOD, CAT and MDA) observed in the kidney and especially in the liver of the rats co-exposed to Cd and EtOH may result from an independent effect of Cd and/or EtOH and also from their interaction. The interactive effect may involve, among others, changes in Cd accumulation and content of Zn, Cu and Fe in these organs and their concentration in serum. Since the rats treated with Cd and Cd+EtOH had reduced drinking fluids intake that might result in dehydratation, the effect of the both xenobiotics on the oxidative status of the body may be not solely due to Cd and/or EtOH, but also the modyfing influence of accompanying alterations such as reduced water intake and dehydratation. The results of the study allow us to hypothesize that Cd-exposed alcohol misusers are not at enhanced risk of liver and kidney damage due to lipid peroxidation.