Age-related behavioural abnormalities in C57BL/6.KOR-Apoe ^shl mice

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.