Vitamin B6 Dependence of Selenomethionine and Selenite Utilization for Glutathione Peroxidase in the Rat

Abstract

The biological availability of selenium from sodium selenite and selenomethionine for glutathione peroxidase activity was studied. Rats were fed ad libitum for 2 weeks a basal diet deficient in both selenium and vitamin B₆, and then for the subsequent 2 weeks the same diet supplemented with vitamin B₆ (2.5 µg as pyridoxine·HCl/g diet) or selenium (2 µg/g diet) or both. In the presence of vitamin B₆, selenite and selennmethionine increased equally the glutathione peroxidase activity in both the liver and erythrocytes above that of selenium-unsupplemented controls. In the absence of vitamin B₆, selenomethionine was less effective in the liver and ineffective in the erythrocytes while selenite was equally effective in both tissues and was as effective as in the presence of vitamin B₆. These results indicate that selenite selenium is readily available for glutathione peroxidase induction as compared with selenomethionine, and establish that vitamin B₆ is involved in the metabolism of selenomethionine to supply slenium for glutathione peroxidase.