Vasopressin and aggression in cross-fostered California mice (Peromyscus californicus) and white-footed mice (Peromyscus leucopus)

To examine how developmental experiences alter neural pathways associated w ith adult social behavior, we cross-fostered pups between the more aggressi ve and monogamous California mouse (Peromyscus californicus) and the less a ggressive and polygamous white-footed mouse (P. leucopus). Cross-fostered m ales became more like their foster parents when tested as adults. Male whit e-footed mice became more aggressive only in an aggression test in a neutra l arena, whereas the territorial California mice became less aggressive in resident-intruder aggression, test, as measured by attack latency. Only the species that displayed a change in resident-intruder aggression showed a c hange in arginine vasopressin (AVP) levels: cross-fostered California mice had significantly lower levels of AVP-immunoreactive (AVP-ir) staining than controls in the bed nucleus of the stria terminalis (BNST) and the supraop tic nucleus (SON) and a nonsignificant trend toward lower levels in the med ial amygdala (MA). Neither species showed changes in AVP-ir staining in a c ontrol area, the paraventricular nucleus (PVN). The changes in AVP-ir stain ing in the BNST and SON may not be caused by stress because cross-fostering was not associated with changes in adult plasma concentrations of two ster oid hormones, corticosterone and testosterone, that have, been associated w ith stress-related alterations in AVP pathways. These results suggest that manipulating the early parental environment can directly alter both a neuro transmitter system and species-typical patterns of social behavior, but tha t these effects may vary between species and under different social context s. (C) 2001 Academic Press.