Figure 6.

Schematic of hypothesized relationships among neuronal nitric oxide synthase (nNOS), aggression, and motivation to explore social cues. We propose that pair housing decreases social investigation by decreasing vasopressin function. A more conclusive link has been defined between pair housing and serotonin function, which we suggest mediates the effect of pair housing on aggression. Prior studies have demonstrated that the effects of nNOS deletion on aggression are mediated by reduced serotonin function. We propose that nNOS increases social investigation by increasing dopamine function.