[Age-related memory impairment and hippocampal damage in ddY male mice]

The relationship between behavioral change and hippocampal lesion was studied in ddY male mice, at 4.5, 20, 40 and 60 weeks of age. In passive avoidance response, the aging mice (40 and 60 weeks of age) showed shorter latency than young mice (4.5 weeks of age). The degenerated pyramidal cells were more numerous after 40 weeks of age in the CA3 than CA1. The mean incidence of the degenerated pyramidal cells in the CA3 was 20.8% at 60 weeks of age. In 71.9% of mice, impairment of passive avoidance response was associated well with hippocampal lesions. These results indicate that the hippocampus plays some role in the memory in mice. The ddY mice may be possible to use as models for reversible hippocampal lesion.