Effects of early deprivation and maternal separation on pup-directed behavior and HPA axis measures in the juvenile female rat.

Juvenile female rats show maternal-like behavior toward pups. The purpose of the following experiment was to investigate whether the HPA axis, through the use of early separation manipulations that alter HPA functioning in rats, plays a role in the juvenile response to foster pups. Female rats were early deprived or maternally separated for 5 hours daily from PND 2 to 14 and compared to animal facility-reared rats. Deprivation or separation increased CRH-R1 IR in the juvenile PVN, but had no other effects on other HPA measures or on maternal behavior. Pup-exposure during the juvenile period blunted corticosterone levels after acute and repeated pup-exposures when compared to exposure to novelty and conspecifics respectively. Repeated exposures to pups also increased CRH-R1 IR relative to isolation during the juvenile period. Overall, the data suggest that although pup-exposure affects corticosterone levels, the HPA axis does not relate to juvenile maternal behavior in the present experiments.