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

The effects of nimodipine were investigated on performance of rats wit h 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-nimod ipine, lesion-vehicle, and lesion-nimodipine. The doses of nimodipine used were 3, 10, and 30 mg/kg, p.o. Sham or lesion surgeries were perf ormed and drug or vehicle treatments started after surgery, and contin ued for the duration of the study. Seven days postsurgery, the rats we re given a second probe trial, followed by 4 additional training trial s. A third probe trial was then conducted. Prior to surgery, all the r ats performed equally during initial training. On the first probe tria l, the amount of time spent in the goal quadrant was greater than chan ce for all animals. After surgery, during the second probe trial, no s ignificant drug and/or lesion effects were found. During the third pro be trial, however, the performance of the lesion-vehicle animals was n ot greater than chance. In nimodipine-treated rats, as in sham control s, this deficit was not found. These results indicate that nimodipine can protect against medial septal lesion-induced retention deficits.