Transgenerational effects of social environment on variations in maternal care and behavioral response to novelty.

Cross-fostering studies in the rat have illustrated the importance of the postnatal environment in mediating the transmission of maternal licking/grooming (LG) from mother to offspring. The authors addressed the question of how postweaning social conditions can alter the patterns of maternal behavior. Juvenile female offspring of high LG and low LG mothers were placed in either standard, enriched, or impoverished postweaning environments for 50 consecutive days and then mated and observed with their own litters. Analysis of LG behavior indicated that the effect of postweaning environment was dependent on the level of postnatal mother-infant interaction. Postweaning isolation reduced exploratory behavior, maternal LG, and oxytocin receptor binding in the offspring of high LG mothers, whereas social enrichment enhanced exploration, LG behavior, and oxytocin receptor binding of low LG offspring. These effects were also transmitted to the next generation of offspring. Thus, maternal LG and the neural mechanisms that regulate this behavior exhibited a high degree of plasticity in response to changes in environment both within and beyond the postnatal period, with implications for the transmission of behavioral response to novelty and maternal care across generations.