[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.