Apodemus sylvaticus (LOXT) is a suitable mouse strain for testing spatial memory retention in the Morris water maze

Information on the difference in cognitive function between laboratory and wild-caught mice is anecdotal and this question has not been systematically studied. Moreover, studying a wild-caught mouse strain per se may add information to the repertoire of mouse strains available. We aimed to study spatial memory in a wild mouse strain (Apodemus sylvaticus, AS) as compared to two individual laboratory mouse strains. Male AS (n=20), CD1 (n=19) and C57BL/6J mice (n=19), 12-14 weeks old, were used in the experiments. The Morris water maze (MWM) was used for determination of spatial memory and time spent in the target quadrant at time points 5 (D5) and 12 days (D12) was evaluated. During the acquisition phase latency to reach the platform and path length to reach the platform was evaluated. Following four training days on day 5 (D5), time spent in the target quadrant was highest in AS>CD1>C57BL/6J (P<0.006). On day 12 (D12), time spent in the target quadrant was significantly higher in AS than in both other strains (P<0.001). All animals learned the task and during the acquisition phase, latency to reach the platform as well as path length decreased significantly in AS. It is concluded that the AS is the most suitable strain for the evaluation of spatial memory in the MWM and is presenting with memory retention superior to laboratory mouse strains CD1 and C57BL/6J.