Inhibitory Effect of Selenium on N-Nitrosodiethylamine and Phenobarbital-Promoted Rat Liver Carcinogenesis

The chemoprotective efficacy of selenium, a dietary micronutrient, against chemically-induced hepatocarcinogenesis in rats was investigated. Carcinogenesis was performed by a single intraperitoneal injection of N-nitrosodiethylamine (DEN, 200mg/kg body weight) with phenobarbital (0.05%) as a promoter in rats. When selenium-supplemented (4ppm) drinking water was provided ad libitum throughout the experimental period, before the initiation, or during the promotion period it was found to be effective in elevating hepatic glutathione peroxidase activity to a statistically significant level measured either in hyperplastic nodules or in the non-nodular surrounding tissue compared with the level of the carcinogen control. Selenium treatment also in-creased the activity of this enzyme in kidney, lung, and erythrocytes to a significant level compared with the tissue or cell levels of the carcinogen control rats. A decrease in the number and size of hyperplastic nodules was observed in the selenium-treated groups. Hence, a direct correlation may be made between the hepatic selenium content with the formation of hyperplastic nodules and non-nodular surrounding liver tissues. Our results further confirm the fact that selenium is particularly protective in limiting the action of DEN during the initiation phase of hepatocarcinogenesis.