1. It is known that stress causes disruption of homeostasis and an imbalanced anti-oxidant status in several organs. The aim of the present study was to determine the effects of three stress models on protein oxidation, lipid peroxidation and anti-oxidant enzyme activities in the liver, kidney and heart, and to investigate the relationship between corticosterone and some oxidative stress parameters. In addition, we investigated the most effective stress model for each parameter in each tissue. 2. Thirty-six male Wistar rats (aged 3 months old, weighing 220 +/- 20 g) were divided randomly into four groups of nine rats each: control (C), immobilization stress (IS), cold stress (CS), and immobilization-cold stress (ICS). 3. Results showed that corticosterone levels were increased in all stress groups. Levels of protein carbonyl (PC), conjugated dienes (CD) and thiobarbituric acid-reactive substances (TBARS) were increased, whereas reduced glutathione (GSH) levels were decreased in all tissues of all stress groups. Copper, zinc-superoxide dismutase (Cu,Zn-SOD) activities were increased in the liver and kidney of all stress groups, but were decreased in heart of the IS and CS groups. Catalase (CAT) activities were increased in liver of the CS group and in kidney and heart of all stress groups, but were decreased in liver of the IS and ICS groups. Selenium-dependent glutathione peroxidase (Se-GSH-Px) activities were increased in liver of the CS and ICS groups and in heart of all stress groups, but were decreased in kidney of the IS group. Also, Se-GSH-Px activity levels remained unchanged in liver of the IS group and in kidney of the CS and ICS groups. The increased CAT activity and unchanged Se-GSH-Px activity observed in kidney suggest that H2O2 may be primarily scavenged by CAT. 4. The strong correlations between corticosterone and oxidative damage markers (e.g. protein oxidation, lipid peroxidation and GSH levels) suggest a relationship between these parameters. Liver was affected most by the CS model, whereas kidney and heart were affected most by ICS model. Stress-induced changes in the activities of anti-oxidant enzymes and GSH levels were found to be tissue- and enzyme-specific. In conclusion, results of the present study suggest that each stress model affects the different organ tissues in different ways.
