Dietary Selenium and Age-Related Susceptibility of Rat Erythrocytes to Oxidative Damage

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Abstract
The effects of age and dietary selenium on cellular susceptibility to oxidative stress were studied in rat erythrocytes. Young (26 or 40 days) and mature adult (11 or 15 months) male rats were fed a Torula yeast-based low selenium and low vitamin E diet supplemented with either 0, 1.0 or 2.0 ppm selenium (as sodium selenite) for 5 weeks. The rates of spontaneous hemolysis and methemoglobin formation and levels of glutathione (GSH), glucose-6-phosphate (G6P) dehydrogenase, but not of GSH peroxidase, GSH reductase, superoxide dismutase and catalase were significantly higher in the erythrocytes of young rats than in those of the adults. Adult rats, however, had higher levels of plasma vitamin E and GSH peroxidase than those of the young group. Dietary selenium markedly increased activity of plasma GSH peroxidase and partially retarded the rates of hemolysis and methemoglobin formation, but it had no significant effect on the erythrocyte levels of GSH, GSH reductase, catalase, G6P dehydrogenase and superoxide dismutase or plasma vitamin E levels of young rats. Except for GSH peroxidase activity, dietary selenium had no significant effect on any other measurements made in the erythrocytes or plasma of adult rats. The results suggest that the ability of adult rats to retain higher levels of vitamin E and selenium than the young rats may be partly responsible for the increased resistance of their erythrocytes against oxidative stress.