Glutathione peroxidase activity in rat lens and other tissues in relation to dietary selenium intake

Abstract

Glutathione peroxidase (E.C. 1.11.1.9: glutathione: H 2O 2 oxidoreductase) activity and selenium concentration were measured in lenses of female rats and their offspring after long-term feeding of either a selenium-supplemented ( 0·1 parts 10 6 ) or selenium-deficient ( < 0·02 parts 10 6 ) diet. Long-term selenium deficiency decreased lens glutathione peroxidase activity in parent rats and their offspring to 15 and 14% respectively of supplemented controls. For comparison to lens, glutathione peroxidase was also measured in liver, heart, lung, erythrocytes, kidney, adrenal, testis, and brain of the offspring. Selenium deficiency caused the enzyme to decrease most dramatically in liver (to 0) and least in brain (to 62% of selenium supplemented controls). Although glutathione peroxidase in lens was lower than that in the other organs assayed, it was among the organs more sensitive to depletion caused by selenium deficiency. A short-term selenium deficiency of 8 weeks in newborn lambs had no effect on lens glutathione peroxidase, but the enzyme in organs such as liver was dramatically decreased. Therefore, an extensive period of selenium deficiency appears necessary to affect lens glutathione peroxidase activity, which probably relates to the relatively slow turnover and slow growth of the lens. The possible role of the seleno-enzyme, glutathione peroxidase, in the prevention of cataracts and the relationship of selenium to vitamin E and sulfur-containing amino acids in this regard are discussed.