As observed in Fig. 1, the number of crossings (Fig. 1A) and rearings (Fig. 1B) were significantly (p < 0.05) lower in MeHg-treated mice, when compared to untreated controls. There was a significant decrease in the activity of GPx in the cerebellum (Fig. 2A; p < 0.001) and cerebral cortex ( Fig. 2B; p < 0.05) of MeHg-treated mice. TrxR activity was also decreased in both brain structures (cerebellum

– p < 0.001; cerebral cortex – p < 0.05) of MeHg intoxicated animals ( Fig. 2C and D). We analyzed the expression (protein levels) of GPx1, GPx4 and TrxR1 by Western blotting. As observed in Fig. 3, there was a significant decrease in the levels of these selenoproteins in the cerebellum of treated PFT�� cell line mice, when compared to control. Fig. 3A shows representative blots of immunoreactive bands for GPx1, GPx4, TrxR1 and β-actin (loading control) in the cerebellum of controls and MeHg treated animals. Fig. 3B–D represent the densitometric this website analysis of immunoreactive bands for GPx1 ( Fig. 3B), GPx4 ( Fig. 3C) and TrxR1 ( Fig. 3D) in the cerebellum. The results are expressed as ratio of target protein/β-actin and controls were considered as 100%. Fig. 4A shows representative blots of immunoreactive bands for GPx1, GPx4, TrxR1 and β-actin in the cerebral cortex

of controls and MeHg treated animals. Fig. 4B–D represent the densitometric analysis of immunoreactive bands for GPx1 ( Fig. 4B), GPx4 ( Fig. 4C) and TrxR1 ( Fig. 4D) in the cortex. In the cerebral cortex of MeHg-treated mice, we did not observe a significant change in GPx1 expression ( Fig. 4B), when compared to control. The administration of MeHg to mice caused a significant increase (p < 0.05) in the activity of GR ( Fig. 5A), GST ( Fig. 5B), CAT ( Fig. 5C) and SOD ( Fig. 5D) in the cerebellum, when compared to control. In contrast, in the cerebral cortex ( Fig. 6), only CAT activity was altered. It was observed a significant increase (p < 0.05) in the activity of this enzyme in the MeHg-treated animals, when compared to untreated controls ( Fig. 6C). The expression of HSP70 was determined in the brain structures (

Fig. 7). As observed in Fig. 7A, MeHg-treated mice showed an increased expression of this chaperone in the cerebellum. Urocanase The levels of HSP70 were not changed in the cerebral cortex, when comparing MeHg versus control animals ( Fig. 7B). In the last years, reports in literature have pointed oxidative stress as a main mechanism by which MeHg exerts it deleterious effects to the CNS (reviewed by Farina et al., 2011a and Farina et al., 2011b). It was previously demonstrated that inhibition of important antioxidant enzymes activity could, at least in part, be responsible for the oxidative damage caused by this organometal (Carvalho et al., 2008, Carvalho et al., 2011, Farina et al., 2009, Franco et al., 2009, Glaser et al., 2010, Wagner et al., 2010 and Branco et al., 2011).