Abstract
The catalase activity of weanling male mice placed on a riboflavin-deficient diet, and of pair-fed animals receiving a riboflavin supplement, does not show the rise to adult level which normally occurs after 2-3 weeks. The injection of testosterone into mice kept 3 or more weeks on the diets resulted in a rise in catalase activity only in groups receiving riboflavin. No change in catalase level occurred in the riboflavin-deficient groups. The catalase level of female mice was not altered either by riboflavin deficiency or the restriction in total dietary intake involved in pair-feeding. However, the catalase activity of riboflavin-deficient groups was not raised by testosterone injection. Blood hemaglobin level remained normal in riboflavin deficiency. A single injection of a riboflavin antagonist reduced the catalase activity of normal males to the castration level. There was no change in the catalase level of castrated males after the injection of antagonist.