• Sinopotamon yangtsekiense;
  • cadmium;
  • low molecular weight chitosan;
  • combination effects

Cadmium (Cd) is an environmental contaminant showing a variety of deleterious effects, including the potential threat for the ecological environment and human health via food chains. Low molecular weight chitosan (LMWC) has been demonstrated to be an effective antioxidant. Metallothionein (MT) mRNA levels and activities of glutathione-S-transferase (GST), superoxide dismutase (SOD), acid phosphatase (ACP), Na+,K+-ATPase, and Ca2+-ATPase as well as malondialdehyde (MDA) contents in the gills of the freshwater crab Sinopotamon yangtsekiense were analyzed in vivo in order to determine the injury of Cd exposure on the gill tissues as well as the protective effect of LMWC against this injury. The results showed that there was an apparent accumulation of Cd in the gills, which was lessened by the presence of LMWC. Moreover, Cd2+ significantly increased the gill MT mRNA levels, ACP activity and MDA content while decreasing the activities of SOD, GST, Na+,K+-ATPase, and Ca2+-ATPase in the crabs relative to the control. Cotreatment with LMWC reduced the levels of MT mRNA and ACP but raised the activities of GST, Na+,K+-ATPase, and Ca2+-ATPase in gill tissues compared with the crabs exposed to Cd2+ alone. These results suggest that LMWC may exert its protective effect through chelating Cd2+ to form LMWC-Cd2+ complex, elevating the antioxidative activities of GST, Na+,K+-ATPase, and Ca2+-ATPase as well as alleviating the stress pressure on MT and ACP, consequently protecting the cell from the adverse effects of Cd. © 2012 Wiley Periodicals, Inc. Environ Toxicol 29: 298–309, 2014.