BACKGROUND: Epidemiological studies suggest that environmental adversity can alter parental care and thus influence child development. We addressed the question of whether stressors can directly affect parental behavior using a rodent model of stable, individual differences in maternal behavior.

METHODS: Lactating rat mothers were characterized as high or low in pup-directed licking/grooming (LG) behavior, rebred, and subjected to 7 days of intermittent stress or control conditions during gestation. Female rats were mated a third time without any subsequent intervention. Maternal behavior, oxytocin receptor (OTR) binding, and offspring behavior were examined.

RESULTS: Stress reduced OTR levels and pup LG of high LG mothers to levels comparable with those of low LG mothers. The adult offspring of the gestational stress/high LG mothers resembled those of low LG mothers on behavioral measures of anxiety and maternal behavior, as well as OTR levels. The results of the third mating revealed an enduring effect of gestational stress on both mother and offspring maternal LG.

CONCLUSIONS: These findings suggest that stress can directly alter maternal care through the neuroendocrine systems that normally regulate this behavior. Thus, the effects of environmental adversity can be transmitted across generations through a nongenomic mechanism involving maternal care.