, 2009 and Wagner GKT137831 cell line et al., 2010). The selenoproteins GPx and TrxR have been

described as important antioxidant enzymes in the cellular protection against damage caused by ROS (Reeves and Hoffmann, 2009). The glutathione antioxidant system includes reduced glutathione (the most important low-molecular-weight sulfhydryl-containing antioxidant) and the GSH-related enzymes GPx and glutathione reductase (GR) (Dringen, 2000). Mammalian cells contain five isoforms of selenium-dependent GPxs: cytosolic GPx (GPx1), gastrointestinal GPx (GPx2), plasma GPx (GPx3), phospholipid hydroperoxide GPx (GPx4), and, in humans, GPx6, expressed only in the olfactory system (Brigelius-Flohe, 2006). GPx1, also called cytosolic or cellular GPx, is the most prominent GPx isoform and it is able Z-VAD-FMK cell line to reduce hydrogen peroxide and a range of organic peroxides, including cholesterol

and long-chain fatty acid peroxides, by expending GSH (Sunde, 1997 and Arthur, 2000). GPx4 is expressed in a variety of tissues, however its subcellular localization is tissue dependent (Conrad et al., 2007). The main substrate for GPx4 is phospholipid hydroperoxides, a fact that may indicates the crucial role of GPx4 in the counteraction of lipid peroxidation (Brigelius-Flohe, 2006). Thioredoxin reductase (TrxR) enzymes are antioxidant proteins that catalyze the reduction of oxidized thioredoxin by expenses of NADPH (Arner and Holmgren, 2000). There are three mammalian TrxRs described. TrxR1 (cytosolic/nuclear) and TrxR2 (mitochondria) are distributed in several tissues and TrxR3 is testes specific (Rundlof and Arner, 2004). Although recent studies have demonstrated that MeHg causes TCL decreases in the activity of GPx and TrxR, it is still unknown whether this process involves a protein expression alteration or a post-translational modification on the enzymes by this organometal. Thus, the aim of this study was to evaluate the activity and expression, in terms of protein levels, of GPx1, GPx4

and TrxR1 in a mouse model of MeHg exposure in vivo. Glutathione reductase (G3664), glutathione reduced (GSH), glutathione oxidized (GSSG), t-butyl-hydroperoxide (t-bOOH), 5,5′-dithio-bis(2-nitrobenzoic acid (DTNB), β-Nicotinamide adenine dinucleotide 2′-phosphate reduced tetrasodium salt hydrate(NADPH)Methylmercury (II) chloride, protease inhibitor cocktail were purchased from Sigma–Aldrich (St. Louis, MO, USA). All antibodies utilized in this study were purchased from Santa Cruz Biotechnology (Santa Cruz, CA, USA). All the other chemicals used in this work were from the highest analytical grade. Swiss mice were used from the Central Animal Facility of the Federal University of Santa Maria. The animals were kept in a vivarium in cages with free access to food and water at a controlled temperature (22 ± 3 °C) and a light/dark cycle of 12:12 h.