Age-related impairment in learning but not memory in SAMP8 female mice

Four-month and 12-month-old SAM (Senescence Accelerated Mouse)-P8 and -R1 female mice, either intact or ovariectomized, were trained to avoid foot shock in a T-maze. Mice were trained until they made their first avoidance. Memory retention of this task was then tested 1 week later. The results indicated that P8, but not R1, female mice whether intact or ovariectomized, showed an age-related learning impairment. This impairment was more apparent in ovariectomized mice, as ovariectomy was associated with a significant reduction in the mean trials to make an avoidance in all groups except 12-month P8 females. Of greatest interest was the absence of any age-related impairment of retention in P8 females. In several previous studies, SAM-P8, but not R1, males showed an age-related impairment of learning and memory. These results indicate that age-related impairment of memory in P8 mice may be inherited in a sex-related manner, and suggests that the mechanisms involved in the development of impaired learning and memory are different.