Effects of selenium supplementation on malignant lymphoproliferative pathologies associated with OF1 mouse ageing.

Low plasma selenium (Se) levels have been shown to correlate with increased cancer incidence in humans and in mice. This study was undertaken to investigate the ability of Se to decrease mortality rate and tumor production in ageing mice. Se (2.5 ppm) given as sodium selenite in drinking water to 8 months old OF1 mice, for 4 consecutive months, reduced significantly the mortality of mice with 6% and 50% mortality rate for Se and control groups, respectively. In addition 80% of control deaths resulted from a lymphoid cell neoplasma, while no one of Se supplemented mice produced tumor. Evaluation of parameters of free radical metabolism showed highly significant reduction of the antioxidant defence system in the liver of cancer mice, with a 78% decrease in GSH-Px activity, a 65% decrease in superoxide dismutase (SOD) activity, a 75% decrease in the GSH/GSSG ratio and a 62% decrease of plasma Se level, as compared to healthy old mice. Nevertheless in the conditions of our experiment, Se didn't really improve the endogenous antioxidant status of ageing mice.