Age-related decline in water maze learning and memory in rats: strain differences

Rats display an age-related impairment in learning and memory; however, few studies have systematically examined this relationship in multiple strains . The present study used a repeated acquisition water maze task to test the hypothesis that age-related decreases in learning and memory occur at diff erent rates in three strains of rats, i.e. Sprague-Dawley (SD), spontaneous ly hypertensive (SHR), and Wistar Kyoto (WKY) rats. All three strains of ra ts displayed age-related decreases in spatial learning and memory; however, the rate of decline differed between the strains. Compared to young rats o f the same strain, only SHR were significantly impaired at 12 months of age . All three strains displayed moderate impairment in learning the task at 1 8 months of age, and at 24 months of age all three strains of rats were sev erely impaired in the task, but SD performed best at 18 and 24 months of ag e. Further, SD and SHR displayed a probe trial bias at 3 months of age, but only SD had a bias at 12 months of age and none of the rats showed the bia s at later ages. Thus, in these three strains, age-related impairment of sp atial memory proceeds at different rates. (C) 2000 Elsevier Science Inc. Al l rights reserved.