Sex differences in the glutathione peroxidase activity of various tissues of the rat.

The glutathione peroxidase activity of blood, liver and brain of sexually mature male and female rats has been determined using both hydrogen peroxide and cumene hydroperoxide as substrates. No significant differences were found on comparison of the glutathione peroxidase activity of the brain tissues of male and female animals. Observed mathematically significant differences between the enzyme activity in the blood of male and females were probably of little physiological significance. Both selenium and non-selenium dependent glutathione peroxidase activities were significantly higher in the livers of female rats but this was much more apparent when cumene hydroperoxide was reduced. Castrated male rats had significantly higher hepatic enzyme activities, approaching those of the female animals. The lipoperoxide concentration was significantly higher in the livers of female rats.