Comparison between the timing of the occurrence of taste sensitivity changes and short-term memory decline due to aging in SAMP1 mice.

Several studies have suggested that cognitive impairment affects taste sensitivity. However, the mechanism behind this is still unclear. In this study, we focused on short-term memory. Using senescence-accelerated mouse prone 1 (SAMP1) mice, we compared whether the effects of aging are observed earlier in taste sensitivity or short-term memory. We used 8-week-old mice as the young group, and 70- and 80-week-old mice as aged groups. Taste sensitivity was evaluated using a 48-hour two-bottle preference test, and short-term memory was evaluated using the Y-maze test. SAMP1 mice showed apparently changes in taste sensitivity at 70-weeks-old. However, the influence of aging on spontaneous alternation behavior, which is indicative of short-term memory alterations, was not observed in 70-week-old mice. At 80-weeks-old, the influence of aging was observed, and spontaneous alternation behavior was significantly decreased. This suggests that age-dependent changes in taste sensitivity occur prior to short-term memory function decline. In addition, there was no significant influence of aging on the mRNA expression of long-term potentiation-related genes in the hippocampus of 80-week-old mice. Therefore, the age-related decline of short-term memory may not affect taste sensitivity.