Long-term effects of the periadolescent environment on exploratory activity and aggressive behaviour in mice: social versus physical enrichment (2004)

Pietropaolo, S., Branchi, I., Cirulli, F. et al.

Abstract

The aims of the present study were (i) to investigate the effects of environmental enrichment during periadolescence on different behavioural and neurochemical responses in male CD-1 mice at adulthood and (ii) to describe the relative role of the physical and social components of the enrichment in producing these effects. Thirty 5-day-old mice were randomly assigned to one of the following housing conditions lasting five consecutive days: (i) individually housed in a standard cage, (ii) housed in pairs in a standard cage, (iii) individually housed in a physically enriched cage, and (iv) housed in pairs in a physically enriched cage. At adulthood, 80 days after the enrichment exposure, the explorative behaviour in an open field, as well as behaviour in agonistic encounters, was evaluated in association with the analysis of central (hypothalamic levels of nerve growth factor (NGF) and brain-derived growth factor(BDNF)) and peripheral (plasma corticosterone levels) biochemical parameters. The results show that the long-term effects of the physical and the social enrichment are different not additive. In particular, while social enrichment by itself exerted very limited effects, physical enrichment decreased the exploratory activity and altered social behaviour.