Sublethal zinc and copper exposure affect acetylcholinesterase activity and accumulation in different tissues of Leporinus obtusidens.

In this study, we investigated zinc and copper effects on acetylcholinesterase (AChE, EC. 3.1.1.7) activity and metal accumulation in tissues of native fish Leporinus obtusidens (piava). Fish were exposed to 10 and 20 % of the LC(50) that corresponded at 2.28 and 4.57 mg/L (zinc) and 0.018 and 0.038 mg/L (copper) for 30 and 45 days. The AChE activity was evaluated in brain and white muscle of fish and metals accumulation was measured in kidney, liver, muscle and brain. Exposure to zinc and copper significantly increased AChE activity in both tissues and times tested, except for brain AChE activity at 2.28 mg/L of Zn (II) after 45 days where a reduction of 52.5 % was observed. Fish exposed to zinc showed accumulation of this metal in liver and kidney in both concentrations and times tested. A different result was obtained for copper: significant copper accumulation was obtained only in brain at both concentrations tested after 45 days of exposure. These results suggest that piavas exposed to zinc and copper showed changes in AChE activity and also demonstrate accumulation in some tissues. These results demonstrate that L. obtusidens could be a good bioindicator to evaluate water containing metals. The metal accumulation absence in muscle tissue is an indicative of low potential contamination by metals in this fish species.