Partial reversal of the effect of maternal care on cognitive function through environmental enrichment.

Maternal care influences hippocampal development in the rat. The offspring of mothers that exhibit increased levels of pup licking/grooming and arched-back nursing (High LG-ABN mothers) show increased hippocampal N-methyl-D-aspartate (NMDA) receptor binding and enhanced hippocampal-dependent spatial learning. In these studies we examined whether environmental enrichment from days 22-70 of life might reverse the effects of low maternal care. Environmental enrichment eliminated the differences between the offspring of High and Low LG-ABN mothers in both Morris water maze learning and object recognition. However, enrichment did not reverse the effect of maternal care on long-term potentiation in the dentate gyrus or on hippocampal NMDA receptor binding. In contrast, peripubertal enrichment did reverse the effects of maternal care on hippocampal alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor binding. These findings provide evidence for the reversal of the effects of reduced maternal investment in early life on cognitive function in adulthood. Such effects might involve compensatory changes associated with peripubertal enrichment.