DIFFERENTIAL LATERAL SEPTAL VASOPRESSIN IN WILD-TYPE RATS - CORRELATION WITH AGGRESSION

The vasopressin (VP)-containing projections from the cells of the bed nucleus of the stria terminalis to the lateral septum (LS) are sexuall y dimorphic and dependent on gonadal steroids. Recently, the differenc e in VP distribution found among both sexes was also demonstrated in m ale mice genetically selected for different levels of intermale aggres sion. In the present study we examined whether this differential VP di stribution in males also exists in an outbred strain of wild-type rats . After the animals were tested for their level of aggression, the VP content and the fiber density of the LS were measured using radioimmun oassay and immunocytochemistry, respectively. In addition, basal level s of plasma testosterone (T) were measured. Both biochemical data and immunocytochemical data revealed a negative correlation between VP and intermale aggression. Aggressive rats exhibited low levels of VP wher eas intermediate and nonaggressive animals showed higher levels. Diffe rences in adult levels of T were not found. The results are in accorda nce with the observations previously found in male mice, reconfirming the correlation between lateral septal VP and aggression. (C) 1997 Aca demic Press.