Deficits in aversive but not in safe taste memory in the APPswe/PS1dE9 mice

Age-related changes in taste memory were evaluated in APPswe/PS1dE9 transgenic (Tg) mice and age-matched wild type littermate controls (Wt). These Tg mice produce increasing amounts of amyloid-beta in the brain with age, develop significant amounts of plaques by 9 months of age, and provide an opportunity to study the effects of Alzheimer's disease-like amyloidosis on different aspects of taste memory. In groups of mice ranging from 15-16 months of age, the neophobic response and its attenuation were similar in Tg and Wt mice. However, conditioned taste aversion (CTA), which resulted from the association between a new taste and an artificially induced gastric malaise, was significantly reduced in the 15-16 month old Tg mice compared to the Wt mice, but not in the 3-4 or 7-8 month old mice. The extinction of CTA was normal in 3-4 month old Tg mice, but occurred more rapidly in the 7-8 and 15-16 months old Tg mice than in the age-matched controls. These results provide evidence of differences in the neuronal systems involved in the attenuation of neophobia and CTA and suggest that the progressive amyloidosis that takes place in APPswe/PS1dE9 mice selectively affects the aversion component of taste memory.