Glutathione peroxidase activity in vitamin e and essential fatty acid-deficient rats

Gluthathione peroxidase (EC 1.11.1.9, GSHPx) activity was measured in whole liver, in hepatic cytosol and in whole mitochondria from normal rats and from rats subjected to experimentally induced vitamin e and/or essential fatty acid (EFA) deficiency. The animals were fed and raised on the specific diets for 6 months. The GSHPx activity was significantly decreased in all samples of EFA-deficient rats. This group exhibited a significant increased 29:3omega9 content and to low 20:4omega6 content. In rats fed a vitamin E-deficient diet, the GSHP x activity was significantly decreased in hepatic cytosol. When the data of all experimental groups were pooled the specific GSHP x activities of the hepatic cytosol correlated significantly to that of whole mitochondria. The specific GSHP x activity of the whole liver, the mitochondrial and the cytosol fractions were found higher in female than in male rats in controls as well as in deficient animals. This difference was affected by the EFA deficiency. In EFA-deficient mitochondria the sex difference in enzymic activity was decreased (half of normal difference). In EFA-deficient cytosol the difference was increased (double of normal difference). However, the total hepatic GSHPx activities were not significantly higher in female than in male rats in any of the groups studied. Thus, EFA deficiency is added to the list of factors influencing the GSHPx activity. It is concluded that it is not possible to use GSHPx activity as a marker for the selenium status in domestic animals such as suggested previously. Thus, selenium is only one of the factors governing the GSHPx level.