Induction of Glutathione Peroxidase Activity by Selenium in the Chick ,

The origin of plasma glutathione peroxidase is unclear. Evidence suggests that it is of hepatic origin, but the data are inconclusive. An increase in glutathione peroxidase activity of liver was observed in chicks 4 hr following oral dosage with 20 μg selenium. Activity in plasma was somewhat variable, but tended to remain low following selenium dosage and during the early rise in liver activity. However, 16 hr following dosage, plasma specific activity increased 280%, while that of liver increased 180%. The greatest absolute increase in activity 16 hr after dosage occurred in plasma. Glutathione peroxidase activity changes in plasma did not appear to be closely related to the activity of this enzyme in red blood cells, pancreas, kidney, spleen, or gonad. Ultrafiltration studies failed to demonstrate the presence of a low molecular weight inhibitor in liver or an activator in plasma that might alter enzyme activity.