Effects of folic acid and folinic acid on cognitive and motor behaviors in 20-month-old rats.

Old rats had lower plasma concentrations of folates but not of vitamin B12 than young rats. Old rats injected with pharmacological doses of folic acid (5 mg/kg) or folinic acid (2.5 mg/kg) every 2 days for a 32-day period spontaneously alternated above chance levels at the 0-min retention interval whereas old rats injected with placebo did not. Rats injected with folinic acid that had plasma folate concentrations above the median for that group alternated at the 3-min retention interval whereas none of the other subgroups did. These results indicate that supplementation with folinic acid at pharmacological doses may decrease perseverative responding and improve spatial memory in old rats. However, neither vitamin group was improved in motor coordination, grip strength, or spatial learning in a water maze. There was no hyperactivity or loss of body weight following vitamin supplementation.