Male-specific vasotocin expression in the medaka tuberal hypothalamus: androgen dependence and probable role in aggression

Abstract

AbstractTerrestrial vertebrates have a population of androgen-dependent vasotocin (VT)-expressing neurons in the extended amygdala that are more abundant in males and mediate male-typical social behaviors, including aggression. Teleosts lack these neurons but instead have novel male-specific VT-expressing neurons in the tuberal hypothalamus. Here we found in medaka thatvtexpression in these neurons is dependent on post-pubertal gonadal androgens and that androgens can act on these neurons to directly stimulatevttranscription via the androgen receptor subtype Ara. Furthermore, administration of exogenous VT induced aggression in females and alterations in the androgen milieu led to correlated changes in the levels of tuberal hypothalamicvtexpression and aggression in both sexes. However, genetic ablation ofvtfailed to prevent androgen-induced aggression in females. Collectively, our results demonstrate a marked androgen dependence of male-specificvtexpression in the teleost tuberal hypothalamus, although its relevance to male-typical aggression needs to be further validated.