Changes in the activities of glutathione-S-transferases, glutathione reductase and catalase after exposure to different concentrations of cadmium in Australoheros facetus (Cichlidae, Pisces)

Abstract

The goal of this work was to evaluate the response of the glutathione-S-transferases (GST), glutathione reductase (GR) and catalase (CAT) enzymes in different tissues of the fish Australoheros facetus exposed cadmium (Cd). In liver, a significant decrease of GST activity was observed at 0.031 mg L-1 (p<0.05), while, at higher concentrations, there were non-significant changes compared to controls. Neither the GR nor the CAT activity was different from control. Gills was the most sensitive organ, showing increased GST activity at 0.31 and 1.53 mg L-1 and GR at 3.06 mg L-1; while CAT activity was inhibited at 0.31, 3.06 and 6.13 mg L-1 (p<0.05). The brain GST activity was increased at 1.53 mg L-1 but inhibited at 3.06 and 6.13 mg L-1, meanwhile GR and CAT activities were inhibited at 1.2, 3.06 and 6.13 mg L-1 (p<0.05). The induction of defense enzymes as well as the inhibition of the antioxidant enzyme catalase, even at environmentally relevant concentrations used in this work (e.g. 0.31 mg L-1), denotes the toxic effect that cadmium exerts over the tissues of A. facetus and alerts over the need of doing biomonitoring in areas potentially polluted with metals.