SOCIAL ISOLATION DURING PUBERTY AFFECTS SOCIAL BEHAVIOUR IN ADULT MICE

Early social isolation can have profound consequences on different social behaviours due to alterations in brain structures or gene expressions, but its influence on social recognition or vasopressin (AVP) and oxytocin (OXT) expression has not been thoroughly investigated in mice. We examined social recognition in mice of both sexes that were individually housed from 30 days of age until testing at around day 80, individually housed from day 30 until day 60 and regrouped from day 60 until testing at day 80 and in control mice that were group housed throughout experiment. The ability to recognize familiar mouse was tested using standard social recognition test. Group housed mice showed strong social memory, whereas individually housed did not. Interestingly, mice reared in isolation for a limited period showed reduced social memory, suggesting that even isolation for a limited period can have lasting behavioural deficit, especially in female mice. Using immunohistochemistry we examined vasopressin and oxytocin expression in the brain. As expected, immunohysto-chemical detection of AVP in lateral septum (LS) revealed robust sex difference with males having much more AVP in fibers than females. However, there were no obvious differences in either vasopressin or oxytocin between groups in different housing regimes, suggesting that social isolation in mice has no effect on the expression of these two neurohormones.