Trivalent chromium induces oxidative stress in goldfish brain

Although information on the effects of Cr6+ in biological systems is abundant, Cr3+ has received less attention. Toxic effects of chromium compounds are partially associated with activation of redox processes. Recently we found that Cr6+ induced oxidative stress in goldfish tissues and the glutathione system was shown to play a protective role. The present study aimed to investigate free radical processes in brain of goldfish exposed to CrCl3. Trivalent chromium at a concentration of 50 mg L-1 was lethal and therefore we chose to examine sublethal dosages of 1.0-10.0 mg L-1 in aquarium water. The levels of lipid peroxides and protein carbonyls (measures of oxidative damage to lipids and proteins) in brain increased after 96 h exposure of goldfish to Cr3+. However, exposure to 1.0-10.0 mg L-1 Cr3+ decreased total glutathione concentration in brain by similar to 50-60%. Oxidized glutathione levels also fell by similar to 40-60% except at the 10.0 mg L-1 dosage where they decreased by 85%. Therefore, 10.0 mg L-1 Cr3+ significantly reduced the ratio [GSSG]/[totalGSH] to 35% of the control value. Chromium treatment did not affect the activity of superoxide dismutase, but reduced the activities of catalase by 55-62% and glutathione-S-transferase by 14-21%. The activities of glucose-6-phosphate dehydrogenase and glutathione reductase were unchanged under any experimental conditions used. Therefore, it can be concluded that although Cr3+ exposure induced oxidative stress in goldfish brain, it failed to enhance the efficiency of the antioxidant system in the organ. (C) 2008 Elsevier Ltd. All rights reserved.