Oxidative damages by cadmium and the protective effects of low-molecular-weight chitosan in the freshwater crab (Sinopotamon yangtsekiense Bott 1967)

Cadmium (Cd) is an environmental pollutant and has posed a potential threat for the growth and survival of freshwater crabs. Low-molecular-weight chitosan (LMWC) may promote growth in crab culture. The present study was designed to investigate the Cd-induced oxidative damage and the protective role of LMWC against oxidation caused by Cd2+ in freshwater crab (Sinopotamon yangtsekiense Bott 1967). The results showed that Cd2+ significantly inhibited the activities of total antioxidant capacity, superoxide dismutase, catalase, glutathione peroxidase and peroxidase, while it increased malondialdehyde levels in the hepatopancreas and the gill. Moreover, Cd2+ at the concentration tested obviously increased the protein carbonyl contents and DNA-protein crosslinks coefficients in the hepatopancreas, gill, heart and muscle tissues of S. yangtsekiense in a dose-dependent manner. In addition, Cd2+ induced a significant increase in the levels of nitric oxide and inducible nitric oxide synthase in the hepatopancreas, gill and muscle. The results also showed that LMWC plus Cd2+ significantly improved antioxidant markers. The observations suggested that the severe oxidative damage in multiple crab tissues was one of the important causes of the adverse influence of Cd2+ on S. yangtsekiense growth and indicated that LMWC could provide a protective effect against such an injury.