Fig. 1.

AH-AVP is necessary and sufficient to regulate selective aggression. Male prairie voles that were pair-bonded for 2 weeks displayed robust aggression toward novel females (A) yet maintained a high level of affiliative side-by-side contact with their female partner (B) during a RIT. AVP release in the AH was significantly higher in males exposed to a novel female than in males re-exposed to their female partner (C). AH-AVP concentration was correlated positively with aggression (D) and negatively with affiliation (E). Sexually naive male prairie voles that received intra-AH infusions of a high (500 ng/side), but not a low (5 ng/side), dose of AVP displayed enhanced aggression toward a novel female relative to control males infused with CSF (F). Intra-AH administration of a high (5 μg/side), but not a low (0.5 μg/side), dose of the AVP-V1aR antagonist blocked AVP-induced aggression (F). Further, males with misplaced cannulae did not show AVP-induced aggression (F). For pair-bonded male prairie voles, intra-AH infusions of the AVP-V1aR antagonist blocked aggression (G) and induced affiliation (H) toward a novel female, relative to control males infused with CSF or males with misplaced cannulae. Bars indicate means ± standard error of the mean. Bars with different Greek letters differ significantly from each other. *, P < 0.05.