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In 2007 and 2008, renal stone formation and kidney damage in human infants were linked to consumption of melamine (MEL)-contaminated infant formula, as well as renal failure and death in pets due to pet food containing both MEL and cyanuric acid (CYA). The aim of this study was to examine the effects of MEL and CYA administered individually or in combination on concentrations of certain metabolites and enzyme activities that serve as markers for oxidative stress in kidney and liver of rainbow trout. In addition, the levels of muscle MEL and renal crystal formation were determined. Trout were fed MEL and/or CYA for 8 wk at 250, 500, or 1000 mg of each compound/kg in feed. Fish muscle residues of MEL exhibited a dose-response relationship. Coexposure of trout to MEL and CYA at the highest dose led to lower MEL residue concentrations in muscle compared to exposure to MEL alone. Renal MEL–CYA complexes were found in kidneys of fish treated with combined MEL and CYA. A dose response was evident with respect to both (1) number of trout displaying renal crystals and (2) number of crystals per fish. Changes in concentration of antioxidant parameters, such as glutathione, superoxide dismutase, catalase, glutathione peroxidase, and glutathioneS-transferase, were recorded in both tissues of MEL- and CYA-dosed trout. Lipid peroxidation was more pronounced in kidney than liver. Therefore, feed contaminated with both MEL and CYA could be problematic for fish, as MEL administered to trout, individually or in combination with CYA, may facilitate the onset of oxidative damage in trout. [ABSTRACT FROM PUBLISHER]

Abstract: The effects of a selenium (Se) diet (1.0mg Sekg−1) were investigated on growth, accumulation and antioxidant response in juvenile Tinca tinca at three endpoints (0, 4 and 8 weeks). Growth and condition factor (K >1.5) for both control (0.25mg Sekg−1) and Se tench were not significantly affected. Se exposed fish exhibited the highest Se level in the kidney and the liver after 4 weeks. By feeding more Se the accumulation capacity of tench did not increase and a plateau, mainly for the liver, was thus reached. Se level remained almost constant in the muscle if compared to own control and for each endpoint. Superoxide dismutase activity in both tissues was not affected by Se supplementation and the higher catalase level in the kidney might support the hypothesis that the enzyme was adequate to remove the hydrogen peroxide production following Se exposure. However, supplemented diet with higher Se level could be critical for tench, as it may cause a lowering of glutathione peroxidase and glutathione reductase activities facilitating the onset of oxidative damage. The enhancement of thiol level and glutathione S-transferase activity, mainly in the liver, could be the signals of the only protection against the oxidative damage induced by Se. [Copyright &y& Elsevier]

Many diets employed in aquaculture are enriched with selenium to improve the diet quality and its conservation. The aim of the study was to investigate the effects of a diet enriched in selenium (1.21mgkg−1) on the antioxidant response of Procambarus clarkii (Girard, 1852). Crayfish fed a diet with lower selenium content (0.30mgkg−1) were the control. Selenium accumulation, enzymatic activities, and total glutathione were evaluated in hepatopancreas of adults of both sexes fed with both diets for 50 days at two experimental times (T 30, T 50 days). Treated females exhibited the highest selenium bioaccumulation during both experimental times, while treated males displayed the highest selenium concentration after 30 days, compared to control crayfish. A sex-related difference was found for the response of the analyzed enzymes in the selenium diet-treated specimens. In fact, superoxide dismutase, glutathione peroxidase and glyoxalase I activities in males were more sensitive compared with females, showing depleted activities in both experimental times. Catalase activity was induced in females (T 50), while glutathione S-transferase activity was the highest in treated females and the lowest in treated males, compared with own controls. Only glutathione reductase activity and glutathione content showed the same trend in both sexes, which were both lowered in treated specimens, when compared with control crayfish. This result might be due to the effect of selenium toxicity on this freshwater species. Males and females of P. clarkii showed a different susceptibility to the prooxidant effects in a Se-enriched diet. [Copyright &y& Elsevier]

Highlights: [•] Selenium accumulation in tissues can be reverted after a Se withdrawal period. [•] Selenium concentration decreased slower in muscle than in liver and kidney. [•] Selenium induced changes in levels of antioxidant markers in liver and kidney. [•] Changes of biochemical markers persisted even after the withdrawal period. [Copyright &y& Elsevier]