Disruption of two-way active avoidance behavior produced by nimodipine.

Nimodipine, a voltage-sensitive calcium channel blocker, has been suggested to be a procognitive drug. In the studies reported herein, we found that low doses of IP-injected nimodipine (0.5 and 0.05 mg/kg) impaired two-way active avoidance behavior. The acquisition phase of the training was the same for drug-treated and control animals. However, the nimodipine-injected rats achieved a significantly lower level of performance. The no-shock tests revealed much faster extinction of the learned behavior in drug-treated vs. control animals. These results could be interpreted as indicating learning-disruptive effects of nimodipine.