Involvement of periaqueductal gray area NMDA receptors in endothelin-induced behavioural effects

We investigated the behavioural effects induced by endothelin-1 injected into the lateral-caudal periaqueductal gray matter of freely moving rats. Endothelin-1 induced a dose-dependent longitudinal rolling of the body (barrel rolling) which was prevented by D,L-2-amino-5-phosphonovalerate (2-APV), an N-methyl-D-aspartate (NMDA) receptor antagonist, but not by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), a non-NMDA receptor antagonist. This effect, not reproducible with NMDA alone, indicates that the activation of the NMDA receptors in the periaqueductal gray area may be a necessary, but not sufficient, step for the triggering of endothelin-1-induced barrel-rolling behaviour.