Vitamin E deficiency has different effects on brain and liver phospholipidhydroperoxide glutathione peroxidase activities in the rat

The effect of vitamin E deficiency on glutathione peroxidase activity (GPX) and on the activity of a selenoenzyme (phospholipid hydroperoxide glutathi one peroxidase (PHGPX) was measured in rat brain and liver. In brain, the a ctivity of both enzymes was in the same range in homogenate and in microsom es. In contrast, in liver homogenate, PHGPX activity was approximately 20 t imes lower than that of GPX. Very interestingly, PHGPX activity was signifi cantly decreased in brain microsomes by Vitamin E deficiency, but slightly significantly increased in liver microsomes. In contrast, GPX activity was not affected in brain by vitamin E deficiency, but was significantly lower in liver homogenate and microsomes. Thus, PHGPX activity is partially contr olled by vitamin E in membranes, and PHGPX is probably an enzyme different from GPX. (C) 2000 Elsevier Science Ireland Ltd. Ail rights reserved.