LACK OF GLIBENCLAMIDE OR TEA AFFINITY FOR OPIOID RECEPTORS - FURTHER EVIDENCE FOR IN-VIVO MODULATION OF ANTINOCICEPTION AT K+ CHANNELS

Radioligand binding of the opioid receptor subtype selective ligands, [H-3][D-Ala(2),N-Me-Phe(4),Gly-ol(5)]-enkephalin (DAMGO) (mu), [H-3][D -Pen(2),D-Pen(5)]-enkephalin (DPDPE) (delta) and [H-3]U-69,593 (kappa) , to rat brain particulate preparations was virtually unaffected by 1- 100 mu M glibenclamide (Glib) or tetraethylammonium bromide (TEA). The se results argue against opioid receptor antagonism by Glib or TEA and support the hypothesis that antagonism of opioid-induced antinocicept ion by Glib or TEA occurs at the level of K+ (possibly ATP-sensitive K -ATP) channels.