The effects of cold stress on the antioxidant defense and immune parameters of juvenile Epinephelus moara

Abstract:

Low water temperature is one of the common enviromental stressors for fishes, but no available information could be found on the physiological response to low water termperature for Epinephelus moara. The current study was conducted to investigate the effects of low water temperature stress ( 0-7 days) on the activities of antioxidant enzymes and immune parameters in serum and liver of juvenile E moara, and three water temperatures were set at 9, 13 and 17 ℃,respectively. The result demonstrated that the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) increased with the decreasing water temperature and the increasing stress time. The total antioxidant capacities (T-AOC) and malondialdehyde (MDA) contents showed different trends in the livers of the different temperature treatments, i.e., the trends of “increasing-decreasing” were found in the livers from 9 and 13 ℃ treatments while no significant difference was found in the liver of 17 ℃ treatment. The significant differences were detected in the serum T-AOC and SOD from the beginning to the end of the experiment, and the significant decrease was found on the MDA in the serum. However, the other parameters were not related significantly to the low temperature. As for immune indices in the serum, the trends of “high-low-high” were found in lysozyme (LZM) activities and contents of immunoglobulin M (IgM), but no significant difference was found on the Ig M. In conclusion, the low water temperature stress had the significant effects on the antioxidant and immune abilities for juvenile E. moara, and the low temperature led to the increasing MDA in E. moara, which may induce the synthesis of some antioxidant in the liver.