Dietary nimodipine improves associative learning in aging rabbits.

The effects of oral nimodipine on the acquisition of the conditioned eye-blink response in aging rabbits were examined. Three groups of rabbits were compared: young and aging controls fed NIH-09 rabbit chow and aging rabbits fed rabbit chow containing 860 ppm nimodipine. Aging control rabbits are dramatically impaired in the acquisition of this task compared to young controls. Aging rabbits receiving nimodipine reached a behavioral criterion of 4 conditioned responses in any block of 5 trials significantly faster than aging controls. Young controls reached this criterion faster than the aging controls. There were no significant group effects on either the amplitude or the latency of the conditioned response. This study extends earlier reports that IV nimodipine enhances the associative learning abilities of aging rabbits and examined the route of administration most likely to be used clinically in aging humans.