Learning impairment following acute administration of the calcium channel antagonist nimodipine in mice.

The effects of acute systemic administration of the Ca(2+) channel antagonist nimodipine were examined on learning capacities of adult Swiss mice. Tests included spontaneous alternation behaviour, for spatial working memory; and step-down passive avoidance and place learning in a water maze, for long-term memory. Nimodipine markedly impaired spontaneous alternation at doses of 0.3-1mg/kg i.p., and passive avoidance at doses of 0.3-3mg/kg i.p., as compared to the vehicle-treated animals. At 0.3mg/kg i.p., the drug did not alter motility in an open field, but significantly decreased performances in training trials and retention in the water maze. Subchronic nimodipine 0.3 and 1mg/kg once a day i.p. for 10 days) did not affect performances in the Y-maze and passive avoidance tests. These results show that acute nimodipine administration alters learning in adult mice, and argue for an involvement of voltage-dependent Ca(2+) channels in learning.