Effect of vitamin C on lipid hydroperoxides and carbonyl groups content of rat plasma depending on age and acute heat exposure

Free radicals produced during hyperthermic stress and aging are thought to play an important role in the degenerative process. To investigate the correlation between oxidative damages caused by acute heat exposure or aging, and the protective effect of vitamin C in vivo, we determined the levels of oxidative protein damage, lipid peroxidation, content of endogenous ascorbic acid, and glutathione in the plasma of young and old Wistar rats, subjected or not-subjected to acute heat stress. The results showed that the level of oxidative protein damage (measured as carbonyl content) in plasma was significantly higher in elderly and in heat-exposed animals. Vitamin C treatment led to inhibition on carbonyl production much more pronounced in young heat-exposed than in aged heat-exposed rats. Aging and acute heat exposure correlated positively with increased production of lipid hydroperoxides in rats plasma, but there were no significant differences in lipid hydroperoxides levels between young and old heat-exposed rats, depending on the treatment with vitamin C. Multiple backward regression analysis showed ascorbic acid to be the only determining variable of lipid hydroperoxides levels in unexposed rats. It was concluded that aging and heat exposure instigate an increase of lipid peroxidation and protein oxidation in rat plasma, while vitamin C supplementation significantly counteracts these changes.