Early environmental enrichment prevents cognitive impairments and developing addictive behaviors in a mouse model of prenatal psychological and physical stress.

Environmental enrichment (EE) has shown remarkable effects in improving cognition and addictive behavior. We tested whether EE could help recover from prenatal stress exposure. Mature Swiss Webster male and virgin female were placed together until vaginal plugs were detectable. Next, pregnant rodents were randomized into the control, physically-stressed, and psychologically-stress groups. The application of stress was initiated on the 10th day of pregnancy and persisted for a week to induce stress in the mice. Open field and elevated plus maze (EPM) were utilized as explorative and anxiety assays. As well, a passive avoidance shuttle-box test was carried out to check anxiety-modulated behavior. Morris-Water Maze (MWM) was undertaken to evaluate spatial memory and learning. Conditioned place preference (CPP) test was selected for evaluation of tendency to morphine. Our results showed that prenatal stress elevated anxiety-like behavior in the offspring, which EE could significantly alleviate after weaning. We also found a higher preference for morphine use in the physical stress and psychological stress offspring group. However, no difference was observed among the genders. Application of EE for the stress group improved several parameters of the cognitive behavior significantly. Although prenatal stress can lead to detrimental behavorial and cognitive outcomes, it can in part be relieved by early exposure to EE. However, some outcomes linked to prenatal stress exposure may not be diminished by EE therapy. In light of such irreversible effects, large-scale preventive actions promoting avoidance from stress during pregnancy should be advised.