RESUMO
The aim of this study was to determine whether endemic Antarctic nototheniid fish are able to adjust their liver antioxidant defence system in response to the temperature increase. The activity of the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST) and glutathione reductase (GR) enzymes as well as the content of non-enzymatic oxidative stress markers such as reduced glutathione (GSH), lipid peroxidation (LPO) and protein carbonyl (PC) were measured in the liver of two Antarctic fish species, Notothenia rossii and Notothenia coriiceps after 1, 3 and 6days of exposure to temperatures of 0°C and 8°C. The GST activity showed a downregulation in N. rossii after 6days of exposure to the increased temperature. The activity profiles of GST and GR in N. rossii and of GPx in N. coriiceps also changed as a consequence of heating to 8°C. The GSH content increased by heating to 8°C after 3days in N. coriiceps and after 6days in N. rossii. The content of malondialdehyde (MDA), a LPO marker, showed a negative modulation by the heating to 8°C in N. rossii after 3days of exposure to temperatures. Present results show that heating to 8°C influenced the levels and profiles of the antioxidant enzymes and defences over time in the nototheniid fish N. rossii and N. coriiceps.
