Some anatomical and physiological correlates of social isolation in the young rat

Immediately after weaning, male Wistar rats were either housed in groups of four or isolated for a period of three weeks. At the end of this period, corticosterone, adrenal ascorbic acid and cerebral cortical weight was determined. Isolates did not differ significantly from social controls with respect to terminal body weight, main and accessory sex organ weights, or in ascorbic acid and plasma corticosterone concentrations. However they did have lighter cerebral cortices and also showed an increase in food intake during the light period of the diurnal cycle. From these results there is little to suggest that social isolation is stressful, although it can produce alterations in neuroanatomy which are similar to those seen following environmental impoverishment.