[Activity of enzymatic antioxidant system in the rat tissues under conditions of over- and restricted nutrition].

The state of enzymatic antioxidant system and thyroid status in the rat tissues under early postnatal overnutrition leading to shortening of life-span and calorie-restricted diet extending lifespan have been studied. It was found that the concentration of thyroxine, body weight and content of lipid hydroperoxides in the blood serum and liver post-mitochondrial fraction of rats had been reliably increased. At the same time the concentration of GSH and GSSG, superoxide dismutase, Se-dependent glutathione peroxidase (GP) activities in the liver and GP activity in the blood serum of experimental rats were reduced. The use of calorie-restricted diet for 2 months showed considerable decrease of thyroxine and triiodothyronine concentration, body weight and the content of lipid hydroperoxides in the blood serum of experimental rats compared with control. At the same time GP activity in the liver, Se-dependent GP activity and content of ceruloplasmin in blood of experimental rats were essentially enhanced. The obtained results allow to conclude that from all studied indices the activity of GSH-dependent antioxidant system (especially Se-dependent GP activity) and thyroid status revealed the most sensible changes in response to the used kind of nutrition. Unlike hypocaloric diet overnutrition results in a decrease of Se-dependent GP activity in the liver and blood of rats. That may be the most crucial moment in the maintenance of prooxidant-antioxidant balance of tissues.

[Activity of glutathione-dependent antioxidant system of the rat liver and blood depending on gamma-irradiation and diet].

The role of the glutathione-dependent antioxidant system in the prooxidant-antioxidant balance support was studied in the experiments with Wistar male rat under single gamma-irradiation (8 Gr dose), fed with unbalanced (as to animal proteins and antioxidant vitamins) diet and with addition of Aronia melanocarpa. Single gamma-irradiation of animals led to the decrease of selenium-dependent glutathione-peroxidase activity in the blood plasma and glutathione-S-transferase activity decrease in rat liver mitochondria. Animals which received the unbalanced food allowance under irradiation showed more expressed change of glutathione-dependent antioxidant enzymes activity, namely--proved decrease of glutathione-peroxidase and glutathione-S-transferase activity in liver microsomes and less expressed activation of selenium-dependent glutathione-peroxidase activity in the postmitochondrial fraction of laboratory animals liver. Introduction of the A. melanocarpa food supplement in the unbalanced diet of the laboratory animals which in vitro demonstrated expressed antioxidant and antiradical activity had no effect upon glutathione-peroxidase activity in the investigated tissues. Obtained data concerning significant decrease of the activity of glutathione-dependent antioxidant system and, particularly, of the selenium-dependent glutathione-peroxidase activity under the unbalanced diet condition may be useful in maintenance of prooxidant-antioxidant balance in the tissues of irradiated animals. Allowing for the above stated it is advisable to seek for new food additives which increase activity of the endogenous glutathione-dependent antioxidant enzymes for human tolerance improvement, especially under the unbalanced food allowance condition.