Hypothalamic vasopressin systems are more sensitive to the long term effects of social defeat in males versus females.

•We examined effects of social defeat on vasopressin in males and females.•Vasopressin neurons respond similarly during defeat in both sexes.•Defeat reduced vasopressin cell counts and mRNA in only males after several weeks.•Social defeat abolished aggression in females but not males.•Defeat dissociated vasopressin levels from aggression in males.