Antioxidant responses in Meretrix meretrix exposed to environmentally relevant doses of tributyltin

The effects on reduced glutathione (GSH) levels, glutathione-S-transferases (GST) and glutathione peroxidase (GPx) activities of digestive gland in Meretrix meretrix exposed to tributyltin (TBT) at environmental levels (0.1, 1, 10 ng/L as Sn), in experimental condition, were evaluated. The GST activities in 0.1 ng/L groups were significantly elevated after exposure for 2 days, and were significantly inhibited after exposure to 10 ng/L TBT for 8 and 20 days. The GPx activities were mainly induced by TBT exposure, except the GPx activities in 10 ng/L groups were significantly inhibited after exposure for 2 days. The GSH content was significantly decreased with prolonged exposure. The GSH content, GST and GPx activities in all exposure groups, transferred to clean recovery tanks for 20 days, were recovered to the level corresponding to that of the control group. Taken together, our present studies indicate that exposure to TBT may induce strong production of reactive oxygen species in the clams.