Environmental stimulation influence the cognition of developing mice by inducing changes in oxidative and apoptosis status

Environment condition has been shown to play an important role in brain development. The present study examined the effects of enriched and impoverished environment on both spatial and emotional learning and memory of young mice and explored the underlying mechanisms. 3-week-old mice were housed in enriched environment (n = 10, 10 mice in a large cage with toys and a running wheel), or standard environment (n = 10, 10 mice in a large cage without objects), or impoverished environment (n = 10, single mice in a small cage without objects) for 6 weeks. Then, the spatial and emotional cognition of mice were evaluated by the water maze and step-down inhibitory avoidance test, respectively. To explore the underlying mechanisms, oxidation measurement in hippocampus and medial-temporal lobe cortex (MTLC) and apoptosis examination in hippocampus were performed. Results showed that compared with standard environment group, enriched and impoverished mice exhibited high and low performance levels in behavior tests, respectively. The oxidative status of hippocampus and MTLC were decreased in enriched group but increased in impoverished group. Moreover, changes in apoptosis of hippocampus in these two groups showed the same tendency with oxidative status. These results suggest that environment condition can simultaneously influence spatial and emotional learning and memory, which may result from inducing changes in the oxidative and apoptosis status in associated brain regions. Here, we firstly report using young mice to examine the oxidative status as a primary and direct factor to explore the mechanism of effects of different environment on both spatial and emotional cognition.