[Effects of systemic lidocaine, mepivacaine and bupivacaine on passive avoidance learning in mice].

The effects of local anesthetics on learning were assessed in mice through one trial step-through passive avoidance performance. Lidocaine HCl (10, 20 or 40 mg.kg-1), mepivacaine HCl (15, 30 or 60 mg.kg-1) or bupivacaine HCl (2.5, 5 or 10 mg.kg-1) were injected subcutaneously 10 min before acquisition training. Lidocaine, but not mepivacaine and bupivacaine, reduced the latency in the retention trial conducted 24hr after the training in a dose-dependent manner. However, lidocaine did not alter the latency when it was given 10 min before the retention trial. These results suggest that lidocaine impairs acquisition, but not retention or retrieval phase in the memory process.