PROGRAMMING LIFE HISTORIES: EFFECTS OF STRESS IN ONTOGENY UPON EMOTIONAL REACTIVITY

Rats were handled or shocked three minutes daily during the first 20 days of life, or were nondisturbed controls. Between 21-50 days of life half of each group was subjected to a crowding stress. Between 60-65 days of age the six groups were split and half was subjected to food deprivation while the other half was not. In adulthood all animals were tested for open-field activity and defecation and their adrenal activity was evaluated by assaying for plasma corticosterone. The open-field activity measure found that food deprivation interacted with infantile treatment: animals handled in infancy were more active than nondisturbed controls or those shocked in infancy if they had not experienced deprivation; however, the group shocked in infancy was found to be the most active of the three groups which did receive food deprivation experience. For the open-field defecation measure, a significant interaction was found between crowding and food deprivation with the group that was not deprived and not raised under crowded conditions having the greatest emotional elimination. The corticosterone measure found that the handled groups released the least amount of corticosterone to the novel stimulus while the shocked and control groups did not differ. In addition, those animals receiving crowding immediately after weaning had a greater corticosterone response than the uncrowded animals.