Determination of oxidative stress and activities of antioxidant enzymes in guinea pigs treated with haloperidol

Guinea pigs (Cavia porcellus) were treated with haloperidol (HP), and free radical (FR) and ferric reducing antioxidant power (FRAP) assays were used to determine oxidative stress levels. Furthermore, the superoxide dismutase (SOD), glutathione reductase (GR) and glutathione-S-transferase (GST) activity levels were detected and glucose levels and the reduced and oxidized glutathione (GSH/GSSG) ratio were measured in HP-treated and untreated guinea pigs. The present study demonstrated that the administration of HP causes significant oxidative stress in guinea pigs (P=0.022). In animals treated with HP, the activity of GST was significantly increased compared with a placebo (P= 0.007). The elevation of SOD and GR activity levels and increase in the levels of glutathione (GSH) in HP-treated animals were not statistically significant. In the HP-untreated animals, a significant positive correlation was observed between oxidative stress detected by the FR method and GST (r=0.88, P=0.008) and SOD (r=0.86, P= 0.01) activity levels, respectively. A significant negative correlation between the levels of plasma glucose and oxidative stress detected by the FRAP method was observed (r=−0.78, P=0.04). Notably, no significant correlations were observed in the treated animals. In the HP-treated group, two subgroups of animals were identified according to their responses to oxidative stress. The group with higher levels of plasma HP had higher enzyme activity and reactive oxygen species production compared with the group with lower plasma levels of HP. The greatest difference in activity (U/μl) between the two groups of animals was for GR.