Chromium(III) induces oxidative stress in goldfish liver and kidney

In the environment chromium is found mainly in two valence states—hexavalent chromium (Cr6+) and trivalent chromium (Cr3+). The present study evaluates the effects of Cr3+ exposure on goldfish by analyzing parameters of oxidative stress and antioxidant defense in liver and kidney of fish given 96 h exposures to Cr3+ concentrations of 1, 2.5, 5 or 10 mg/l in aquarium water. Cr3+ exposure did not alter two parameters of oxidative stress—protein carbonyl content and lipid peroxide concentrations in either organ. However, Cr3+ exposure did decrease total glutathione concentration in liver by 34–69% and in kidney to 36–49% of the respective control values. Oxidized GSSG content fell by similar percentages so that the ratio [GSSG]/[total glutathione] remained constant at all Cr3+ exposure levels except in liver under the highest, 10 mg/l, exposure level. In liver, exposure to 1–5 mg/l Cr3+ led to a decrease in the activity of superoxide dismutase (SOD) by 29–36%, and at 10 mg/l Cr3+ the reduction was 54%, whereas in kidney ∼30% reductions in SOD activity were seen at concentrations 1 and 10 mg/l Cr3+. Catalase activity was not significantly affected by 1–5 mg/l Cr3+, but was reduced by 57 and 42% in liver and kidney, respectively. Chromium exposure also reduced the activity of glutathione-S-transferase in both organs by 17–50% but did not affect glutathione reductase or glucose-6-phosphate dehydrogenase activities. A comparison of Cr3+ effects on goldfish liver and kidney metabolism indicates that the trivalent ion induces stronger oxidative stress than Cr6+ at the same concentrations.