THIOREDOXIN REDUCTASE-ACTIVITY IS DECREASED BY SELENIUM DEFICIENCY

Animal thioredoxin reductase is a selenoprotein. In this study, thiore doxin reductase activities in liver, kidney, and brain have been compa red in rats fed selenium-deficient and control diets for 14 weeks foll owing weaning. Selenium deficiency caused a decrease in thioredoxin re ductase activity from control to 4.5% in liver and 11% in kidney. Howe ver, brain thioredoxin reductase activity was not affected by selenium deficiency of this severity. Gold inhibited thioredoxin reductase act ivity in the liver in a manner typical of its effect on selenoenzymes, Repletion of selenium-deficient rats with injections of selenium caus ed thioredoxin reductase activity to increase more rapidly in the live r than glutathione peroxidase activity but more slowly than selenoprot ein P. These results indicate that thioredoxin reductase activity in l iver and kidney is sensitive to selenium nutritional status but that b rain thioredoxin reductase activity is less sensitive. (C) 1997 Academ ic Press.