Physical activity and environmental enrichment: Behavioural effects of exposure to different housing conditions in mice.

Enriched environments and exercise provide complex environmental stimulation that can induce emotional and cognitive changes; however, few studies have evaluated the effects of these two components on other behaviours, such as novelty seeking or pain sensitivity. The aim of the present study was to investigate the influence of voluntary physical activity provided through different housing conditions on anxiety, locomotor activity, pain sensitivity, and exploration. Male mice at postnatal day (PND) 21 and were randomly assigned to one of four different conditions on PND 28: Marlau cages (MC), a standardized cage designed to provide a complex environment; physical exercise in large groups (PE‑8); physical exercise in small groups (PE‑4); or a standard environment (SE).