Chronic administration of the L-type calcium channel blocker nimodipine can facilitate the acquisition of sequence learning in a radial-arm maze

Nimodipine, a dihydropyridine L-type voltage-gated calcium-channel blocker, was examined for its potential effect on the acquisition of a complex-arm sequence task in an automated radial maze. Young (60-day-old) male Wistar rats were injected with saline or nimodipine (5 mg/kg) 15 min prior to radial maze training, or immediately following the radial maze testing. The results of the learning task (over 7 days of testing) showed that rats injected with nimodipine each training session acquired the task more quickly and more efficiently compared to saline-treated animals. There were no significant differences for rats that were pre-/post-treated with nimodipine during the maze-learning task. The number of incorrect arm entries and number of additional lever presses in the same arm were found to be significantly lower in rats treated with nimodipine compared to saline-injected controls. The beneficial effect of nimodipine treatment occurred only in rats that were acquiring the task, and not in rats that had already learned the arm sequence paradigm. There were no potential non-specific influences on locomotor activity or appetite caused by chronic nimodipine treatments. These results strongly suggest that nimodipine can facilitate the acquisition of a complex learning task.