Nimodipine ameliorates aging-related changes in open-field behaviors of the rabbit

The open-field behavior of old rabbits (32-50 months) was compared to that of young-controls (3 months). Old rabbits engaged in less grooming and rearing behaviors and were more active than young controls. The old rabbits demonstrated a pattern of ambulation which did not indicate a preference for any particular area of the open-field. In contrast, young rabbits exhibited a very stereotypic pattern of exploration in the open-field, engaging in relatively low levels of ambulation confined to the area near the sides of the open-field. Old rabbits fed a diet which included 860 ppm nimodipine showed behaviors in the open-field which closely approximated those of the young-controls. Nimodipine-treated rabbits made fewer crossings and more rears and grooms than the old controls. These results indicate that very specific aging-related changes occur in the open-field behaviors of rabbits, and that nimodipine effectively reverses these aging-associated changes. These data are consistent with previous studies that have shown improvements in open-field behaviors by old rats receiving nimodipine.