NIMODIPINE PREVENTS MEDIAL SEPTAL LESION-INDUCED PERFORMANCE DEFICITS IN THE MORRIS WATER MAZE

The effects of nimodipine were investigated on performance of rats with medial septal nucleus lesions in the Morris water maze. The paradigm began with 10 training trials followed by an initial probe trial. The rats were then assigned to treatment groups: sham-vehicle, sham-nimodipine, lesion-vehicle, and lesion-nimodipine. The doses of nimodipine used were 3, 10, and 30 mg/kg, p.o. Sham or lesion surgeries were performed and drug or vehicle treatments started after surgery, and continued for the duration of the study. Seven days postsurgery, the rats were given a second probe trial, followed by 4 additional training trials. A third probe trial was then conducted. Prior to surgery, all the rats performed equally during initial training. On the first probe trial, the amount of time spent in the goal quadrant was greater than chance for all animals. After surgery, during the second probe trial, no significant drug and/or lesion effects were found. During the third probe trial, however, the performance of the lesion-vehicle animals was not greater than chance. In nimodipine-treated rats, as in sham controls, this deficit was not found. These results indicate that nimodipine can protect against medial septal lesion-induced retention deficits.