Effect of low salinity stress on antioxidant function in liver of juvenile Nibea albiflora

To investigate the effect of low salinity stress on antioxdant function of juvenile Nibea albiflora, we set three levels of salinities (9, 16, 23) and salinity of 23 as the control; the tissues were sampled on the 0, 1st, 3rd and 7th day to measure the superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) activities and total antioxidant capacity (T-AOC) in their liver, as well as malondialdehyde (MDA) in their liver and serum. The results show that SOD activity in liver increased first then decreased, and CAT activity showed a decrease-increase-decrease trend under low salinity stress. GSH-Px activities in liver increased significantly (P0.05), and the lower salinity was, the more dramatic the changes were. T-AOC in liver decreased after a significant increase (P0.05) at salinity of 16, but decreased significantly and maintained a low level at salinity of 9 (P0.05). MDA contents in liver and serum at salinity of 9 increased significantly (P0.05); MDA contents in liver fluctuated, and those in serum decreased slightly at salinity of 16. The results suggest that low salinity has significant effect on the antioxidant function of liver from N.albiflora; and the N.albiflora is highly tolerated to low salinity but will consume energy reserve which leads to lower resistance even damage of fish when thestress is too strong.