Effects of housing social context on emotional behaviour and physiological responses in female mice

In laboratory breeding procedures, mice are usually housed in single-sex unfamiliar groups since weaning, while individual housing is widely employed in many experimental settings. While there is a considerable amount of evidence on the behavioural and physiological effects of various social contexts in male mice and rats, few data are available on female mice. We examined short-term modulation of social context in the housing environment on exploratory and emotional behaviours in response to novelty (i.e., free-exploratory open field) and on physiology (i.e. organs and body weight, and basal corticosterone level) of female CD1 mice, taking into account the estrous phase as an additional variable. Living alone or grouped with siblings or with unfamiliar females for a short period (7 days) did not affect any physiological indexes of stress in female house mice and had marginal effects on emotional behaviour. When challenged with a free choice between a novel environment and their home cage, female mice housed with siblings did not differ on any behavioural parameter from females housed with same-aged unfamiliar mice, while individually housed females showed higher propensity to enter the novel arena but no differences in activity or in anxiety as compared to grouped mice. Information about sex specifics under standard housing conditions as well as in response to common laboratory procedures could be important for the understanding of sex differences in vulnerability to psychiatric disorders and response to drug treatment.