Abstract
Spontaneously hyperlipidaemic (Apoe(shl)) mice were discovered in 1999 as mice lacking apolipoprotein E (ApoE) owing to a mutation in the Apoe gene. However, age-related behavioural changes in commercially available Apoe(shl) mice have not yet been clarified. The behavioural abnormalities of ApoE-deficient mice, which are genetically modified mice artificially deficient in ApoE, have been investigated in detail, and it has been reported that they can serve as a model of Alzheimer's disease (AD). To understand whether Apoe(shl) mice can also serve as a murine model of AD, it is necessary to investigate age-related behavioural abnormalities in Apoe(shl) mice. In this study, we conducted a series of behavioural experiments on 7- and 11-month-old Apoe(shl) mice to investigate the behavioural abnormalities associated with ageing in Apoe(shl) mice. In this study, 7-month-old Apoe(shl) mice showed decreased body weight and grip strength compared to age-matched wild-type mice. In the open field test, 7-month-old Apoe(shl) mice showed increased anxiety-like behaviour compared to wild-type mice, whereas 11-month-old Apoe(shl) mice showed decreased anxiety-like behaviour. Moreover, Apoe(shl) mice aged 7 and 11 months had increased serum cholesterol levels. These results indicate that the behaviour of Apoe(shl) mice changes with age. However, 11-month-old Apoe(shl) mice did not show a decline in cognitive function or memory ability similar to murine models of AD. Our findings indicate that Apoe(shl) mice can be used to investigate the function of ApoE in the central nervous system.