Effect of short time captopril administration on spatial memory in aging rats.

Introduction: The brain renin-angiotensin system (RAS) has been reported having a pathological role in age-related impairment in learning and memory. Therefore, angiotensin converting enzyme inhibitors (ACEi) are expected to have positive effects on memory. Longtime treatment with captopril (an angiotensin converting enzyme inhibitor) significantly attenuates the age-related impairment in learning and memory. Methods: In the present study, 24 month old male Wistar rats were divided into four experimental groups (n=8). Captopril treated groups received daily ip injections of captopril at doses of 5, 10, 15 mg/kg/day for one week, the forth group served as control and remained untreated. Learning process was assessed by the reference memory task in the Morris water maze. All rats received water maze training (4 trials/day for 5 days) to assess hippocampal dependent spatial learning and then received a 60-s probe test of spatial memory retention 24 h after the 20th trial. Results: Over 5 days of training, captopril 5, 10, 15 mg/kg/day treatment significantly reduced the latency and path length to finding the escape platform. In probe trails (without platform), on the last day of training, the captopril -treated group spent significantly longer time in the platform quadrant than control animals. Among treated group, 10 /mg/Kg dosage of captopril induced the best rehearsals memory. Conclusion: These results confirm the previous studies that ACEi have a positive influence on memory and it was noticeable that even short time treatment by captopril can improve spatial memory in the aged rats.