The interpretation of physiological correlates of differential housing in laboratory rats

It seems unlikely, however, that one can dismiss the physiological changes seen in individually-housed rats as ‘isolation stress’, and it is possible that the changes in biogenic amines and hormones are related.

Abstract

A critical review is presented of studies in which (for one reason or another) physiological measures in individually-housed rats are contrasted with those of group-housed counterparts. Most studies seem to focus on adrenocortical activity; gonadal hormone secretion and estimation of localized putative neuro-transmitters. An attempt is made to link these factors and to correlate them with the well-documented behavioral changes seen in 'isolated' rats. It is concluded that it is possible that the changes in biogenic amines and hormones are related. It seems unlikely, however, that one can dismiss the physiological changes seen in individually-housed rats as 'isolation stress'. Adrenocortical reactivity may be increased in 'isolated' rats and this may account for their apparent increased basal activity. It is concluded that there is a distinct lack of 'in depth' studies in this area.