Species differences in paternal behavior and aggression in Peromyscus and their associations with vasopressin immunoreactivity and receptors

Previous comparative studies have suggested that the distribution of argini ne vasopressin (AVP) pathways within the brain is associated with species-t ypical patterns of social behavior. In the current study, male parental beh avior and aggression were compared in two species of Peromyscus. As predict ed based on other studies, male mice from a monogamous species, the Califor nia mouse Peromyscus californicus, spent more time providing parental care to offspring than males from a polygamous species, the white-footed mouse P eromyscus leucopus. Sexually naive male California mice also attacked oppon ents more rapidly than whitefooted mice during resident-intruder and neutra l aggression tests;. Since AVP has been shown to modulate these behaviors, we compared the distribution of vasopressinergic neurons and receptors. We predicted that greater AVP-immunoreactive (AVP-ir) staining in the bed nucl eus of the! stria terminalis and AVP receptor density in the lateral septum would occur in the species with low levels of paternal care because this p attern was found in similar comparisons with sexually naive monogamous and polygamous voles. In contrast, in our study, monogamous male mice showed mo re AVP-ir staining in the bed nucleus of the stria terminalis than the poly gamous species, as well as more AVP receptors in the lateral septum. Parent al behavior therefore does not appear to predict differences in patterns of AVP-ir staining and receptor distribution across species or vice versa. We propose the hypothesis that aggression may be better correlated with speci es patterns of AVP-ir staining density and receptor distribution. (C) 1999 Academic Press.