Effects of artificial mothers and visual experience on adrenal responsiveness of infant monkeys.

Abstract

AbstractRhesus monkeys, maternally seprated at birth, were individually housed with a simple artificial mother in cages that were either completely enclosed (Enclosed Group) or had a clear plastic fron that faced the general nursery environment (Visual Group). Animals were removed from the living cage and placed for 1 hr in an enclosed carrying cage, either alone or with the artificial mother, following which blood samples were taken and analyzed for plasma cortisol levels. This procedure was repeated at monthly intervals during the first 7 months of life and at 9 and 12 months. In both groups plasma cortisol levels were higher when the animlas were alone than when the social surrogate was present. Rearing conditions were also effective, as reflected in longitudinal and diurnal contrasts between groups: cortisol levels were consistently high in the Visual Group from the 1st week of life, whereas the developmental pattern was curvilinear for the Enclosed Group. Significant diurnal variation in cortisol level was demonstrated only in the Visual Group.