Understanding the neuroendocrine basis for social anxiety–like behavior in male mice

Estradiol (E2), a sex steroid hormone, plays an essential role in social behavior, including regulating social anxiety, which is anxiety experienced when unknown individuals are encountered. In males, testosterone secreted by the testes is converted to E2 in the brain, and the E2 binds to two types of estrogen receptors (ERs), ERα and ERβ, to regulate social behavior. However, its neuroendocrine basis has not been understood.