Maternal and environmental influences on the adrenocortical response to stress in weanling rats.

Handling rat pups either for 10 or 20 days after birth resulted in a reduction of adrenocortical steroids in the plasma at weaning after the pups were exposed to novel stimuli as compared with controls that were not handled. Nonhandled offspring of mothers which had been handled in infancy also show a reduction in plasma steroids in response to novel stimuli when compared to nonhandled weanling rats of nonhandled mothers. Handling of the offspring when they are infants appears to counteract the influence of the experience of the mother during her infancy.