Effects of Subchronic Manganese Chloride Exposure on Tambaqui (Colossoma macropomum) Tissues: Oxidative Stress and Antioxidant Defenses Diogo Gabriel • Ana Paula K. Riffel • Isabela A. Finamor • Etiane M. H. Saccol • Giovana M. Ourique • Luis O. Goulart • Daiani Kochhann • Mauro A. Cunha • Luciano O. Garcia • Maria A. Pavanato • Adalberto L. Val • Bernardo Baldisserotto • Susana F. Llesuy Received: 29 May 2012 / Accepted: 26 November 2012 Ó Springer Science+Business Media New York 2013 Abstract This study aimed to evaluate oxidative stress parameters in juvenile tambaqui (Colossoma macropo- mum) exposed to 3.88 mg l -1 Mn 2? for 96 hours. Bio- markers of oxidative stress, such as thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD), catalase (CAT), and glutathione-S-transferase (GST) activities, as well as content of reduced glutathione (GSH), were analyzed in gill, liver, brain, and kidney. The presence of Mn 2? in the water corresponded to increased levels of Mn 2? accumulation according to the following sequence: gill [ kidney [ brain [ liver. There was a sig- nificant increase in TBARS levels (40 %) and SOD activity (80 %) in addition to a significant decrease in GSH content (41 %) in gills of fish exposed to waterborne Mn 2? . In hepatic tissue of the exposed animals, TBARS levels decreased significantly (35 %), whereas SOD (82 %) and GST activities (51 %) as well as GSH content (43 %) increased significantly. In brain of exposed juvenile fish, only significant decreases in SOD (32 %) and CAT activities (65 %) were observed. Moreover, the kidney of exposed fish showed a significant increase in TBARS levels (53 %) and a significant decrease in SOD activity (41 %) compared with the control. Thus, the changes in biomarkers of oxidative stress were different in the tissues, showing a specific toxicity of this metal to each organ. Manganese (Mn 2? ), an essential trace metal, is found in all tissues of bacteria, plants, humans, and fish because it is required for normal amino acid, lipid, protein, and carbo- hydrate metabolism in vivo (Erikson et al. 2004). This metal is one of the most abundant elements and is widely used in industry (Gerber et al. 2002), pesticide formula- tions (Belpoggi et al. 2002), glass and ceramic production, and manufacture of dry cell (Srivastava et al. 1991; Mer- gler et al. 1994; Bader et al. 1999). It is also present at very high concentrations in formation water (produced water or oil field brine) from oil and gas extraction (Baldisserotto et al. 2012). Whereas Mn 2? deficiency is extremely rare, toxicity due to Mn 2? overexposure is more prevalent (Crossgrove and Zheng 2004). Mn 2? undergoes oxi- reduction reactions and may have negative physiological effects owing to oxidative stress induction (Huang et al. 2011). Oxidative stress occurs due to either the overproduction of reactive oxygen species (ROS) or a decrease in cellular antioxidant levels. As a metal ion, Mn 2? is toxic because it enhances ROS formation and catecholamine oxidation by products (Prabhakaran et al. 2008; Falfushynska et al. 2011). ROS generated in tissues and subcellular compartments are efficiently scavenged by the antioxidant defense system, which is composed of antioxidant enzymes, such as super- oxide dismutase (SOD), catalase (CAT), glutathione-S- transferase (GST) and nonenzymatic antioxidants, such as D. Gabriel Á A. P. K. Riffel Á I. A. Finamor Á E. M. H. Saccol Á G. M. Ourique Á L. O. Goulart Á M. A. Cunha Á M. A. Pavanato Á B. Baldisserotto Department of Physiology and Pharmacology, Federal University of Santa Maria, Santa Maria-RS, Brazil D. Kochhann Á A. L. Val Laboratory of Ecophysiology and Molecular Evolution, National Institute for Research in the Amazon, Manaus-AM, Brazil L. O. Garcia Institute of Oceanography, Marine Station of Aquaculture, Federal University of Rio Grande, Rio Grande-RS, Brazil S. F. Llesuy (&) Department of Analytical Chemistry and Physical Chemistry, University of Buenos Aires, Buenos Aires, Argentina e-mail: susanallesuy46@hotmail.com 123 Arch Environ Contam Toxicol DOI 10.1007/s00244-012-9854-4