Environmental prenatal stress alters sexual dimorphism of maternal behavior in rats.

The prenatal external environment can affect fetuses, altering the maternal behavior that they express when mature. In the present study, environmental prenatal stress (EPS) was applied to pregnant rats in their final week of gestation, and when their female offspring reached maturity, the long latency effect of the stress on those offspring was ascertained on their induced maternal behavior (MB), accessory olfactory bulb (AOB) morphology and plasma levels of ACTH and corticosterone (Cpd B). EPS reduced: the percentage of these virgins that showed induced MB, their retrieval of foster pups, the time spent crouching, and the quality of nest building; it also increased the incidence of their cannibalism of foster pups. The EPS-treated females presented a male-like pattern of induced MB. They showed increased plasma levels of ACTH and Cpd B and increased numbers of mitral cells in the AOB. These findings provide evidence that stress applied to the pregnant rat produces long-lasting behavioral, neuroanatomical and hormonal alterations in the female offspring that can be observed when they reach maturity.