Influence of dietary selenium on the hepatic and pulmonary enzymes in polychlorobiphenyls-treated rats

One-month-old male Sprague-Dawley rats maintained for 19 weeks on a low selenium diet with or without supplementation of 2.0 ppm selenium were injected intraperitoneally with either 500 mg PCB (Aroclor 1254)/kg body weight or placebo 5 days prior to sacrifice. In addition to aryl hydrocarbon hydroxylase (AHH) activity, PCB treatment also caused a significant increase in hepatic levels of thiobarbituric acid reactants (TBAR), reduced glutathione (GSH), GSH-peroxidase, GSH reductase, glucose-6-phosphate dehydrogenase (G-6-PD), and GSH-S-transferase in rats on the low selenium diet. The non-selenium-dependent form of GSH peroxidase was mainly responsible for the increase of hepatic GSH peroxidase upon PCB treatment. Only the activities of AHH, GSH-S-transferase, and G-6-PD were significantly higher in the liver of PCB-treated rats fed the selenium-supplemented diet. In contrast, except for AHH activity, the lung GSH and related enzymes were not significantly affected by PCB in either of the two dietary groups. The results suggest that dietary selenium deprivation renders the livers of rats more sensitive to PCB effects.