Resumo

Objectives: Since life stressors contribute in some fashion to depression, in the present study we evaluated the effect of chronic variable stress (CVS), an animal model of depression, on some parameters of oxidative stress [thiobarbituric acid reactive substances (TBARS), catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx)], as well as the activity of butyrylcholineterase in blood of adult male rats. Methods and results: Stressed animals were submitted to different mild stressors during 40 days. After CVS, the blood of control and stressed animals were collected and serum, plasma or erythrocytes were used for biochemical analysis. A reduction in weight gain (control: 60.5±16.9; stressed: 29±12.6 n=15) was observed in the stressed group, as well as an increased in immobility time in the forced swimming test (control: 75.9±7.6; stressed: 104.8±32.7 n=15) as compared to controls. Stressed animals presented a significant increase on TBARS (control: 1.41±0.2; stressed: 1.9±0.2; n=8) and SOD/CAT ratio (control: 0.61=0.07; stressed: 0.88=0.02 n=8), but stress did not alter GPx activity (control: 22.95±1.4; stressed: 22.5±1.7 n=8). CVS caused a significant inhibition on serum butyrylcholineterase activity (control: 0.51±0.08; stressed 0.35±0.05 n=8). Conclusions: Although it is difficult to extrapolate our findings to the human condition, the alterations observed in this work may be useful to help to understand, at least in part, the pathophysiology of depressive disorders.