The injection of endothelin-1 (ET-1) (1 pmol/rat) into the dorsolateral periaqueductal gray (PAG) area of freely moving rats induced rotation along the long axis of the body (barrel-rolling). Preinjection (10 min before) of losartan (a selective AT1 receptor antagonist; 50 nmol) to the PAG area reduced the behavioural response to ET-1. In contrast, pretreatment with PD123319 (a selective AT2 receptor antagonist; 50 nmol) did not affect the ET-1-induced barrel-rolling. These results indicate that endogenous angiotensin II, via an action on AT1 receptors, contributes to the barrel-rolling of ET-1 within the brain.