Environmental enrichment effects in social investigation in rats are gender dependent

Environmental enrichment (E) can change neuronal structure, improves learning in various tasks and increases cerebral plasticity. However, no E effects were found in a test measuring social olfactory discrimination memory and, although they have been mainly measured in males, gender differences have been reported in other tests. The aims of the present study were to evaluate gender differential effects of E in the social discrimination paradigm which also involves social olfactory discrimination and in the elevated plus-maze test (EPM) for measuring anxiety. E procedure consisted of a combination of social and physical factors; groups of 11-12 Sprague-Dawley rats were separated by sex in large cages with physical stimulus for a period of 8 weeks starting immediately after weaning. Differential gender E effects appeared in the social exploratory patterns: enriched males showed increased exploratory behaviour towards juvenile rats in comparison to control males, whereas no differences were found in females. No effects of E in social discrimination memory were observed. In the EPM, both enriched male and female rats showed less anxious behaviour than non-enriched animals.