The majority of studies examining the consequences of prenatal stress in rodent models analyze pups having been raised by their biological mother, i.e. the female which experienced stress during her pregnancy. To test whether pregnancy stress changes maternal behavior and thereby - in addition to stress exposure in utero – influences behavior and brain function of offspring, we implemented a fostering model, in which mouse pups that were not stressed in utero, are raised by dams which were exposed to stress during their pregnancy. We found that dams, which were stressed during pregnancy (PS foster dams), unexpectedly displayed slightly more active and passive light time nursing compared to unstressed dams (CON foster dams). Adult male offspring which were raised by a PS foster dam showed significantly less anxiety-like behavior compared to males raised by a CON foster dam, whereas adult female offspring which were raised by PS foster dams displayed increased depressive-like behavior as a tendency. Since the arginine vasopressin receptor 1a (AvpR1a) and the structurally related oxytocin receptor (OxtR) are both closely related to stress-responsiveness, anxiety and depression, mRNA expression of these genes were assessed in the hippocampus of adult male and female offspring. No significant differences in mRNA expression of both receptor types were observed, however, in female offspring of PS foster dams maternal licking/grooming correlated positively with AvpR1a and negatively with OxtR mRNA expression.
These findings indicate that stress during pregnancy does not reduce, but slightly increase maternal behavior, which might lead to sex-specific behavioral outcomes and changes in hippocampal AvpR1a and OxtR mRNA expression in adult offspring.