Selective and non-selective ET antagonists reveal an ET B receptors mediated ET-1-induced behavioural effect in conscious rats

Abstract

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 BQ-788 (an ET B receptor selective antagonist; 5 nmol) or bosentan (an ET A/ET B receptor non-selective antagonist; 10 nmol) to the PAG reduced the behavioral response to ET-1. In contrast, pretreatment with FR139317 (an ET A receptor selective antagonist; 5 nmol) did not affect the ET-1-induced barrel-rolling. These results suggest that barrel-rolling induced by microinjection of ET-1 into the PAG area is predominantly mediated via ET B-like receptors.