Chronic variable stress induces oxidative stress and decreases butyrylcholinesterase activity in blood of rats.

Depressive disorders, including major depression, are serious and disabling, whose mechanisms are not clearly understood. Since life stressors contribute in some fashion to depression, chronic variable stress (CVS) has been used as an animal model of depression. In the present study we evaluated some parameters of oxidative stress [thiobarbituric acid reactive substances (TBARS), catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx)], and inflammatory markers (interleukin 6, C reactive protein, tumor necrosis factor-alpha and nitrites), as well as the activity of butyrylcholinesterase in blood of rats subjected to chronic stress. Homocysteine and folate levels also were measured. Stressed animals were submitted to different mild stressors for 40 days. After CVS, a reduction in weight gain was observed in the stressed group, as well as an increase in immobility time in the forced swimming test as compared with controls. Stressed animals presented a significant increase on TBARS and SOD/CAT ratio, but stress did not alter GPx activity and any inflammatory parameters studied. CVS caused a significant inhibition on serum butyrylcholinesterase activity. Stressed rats had higher plasmatic levels of homocysteine without differences in folate levels. 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.