INVOLVEMENT OF GLUTAMATE RECEPTORS IN THE STRIATAL ENKEPHALIN-INDUCEDDOPAMINE RELEASE

In anesthetized rats, the intrastriatal infusion of the delta-opioid r eceptor agonist, [D-Pen(2),D-Pen(5)]enkephalin, increased the extracel lular concentration of dopamine. This effect was abolished by the NMDA receptor antagonist, /-)-2-carboxypiperazine-4-yl]propyl-1-phosphonat e, but was unchanged by the AMPA (D,L-alpha-amino-3-hydroxy-5-methyl-4 -isoxazole propionate) and kainate receptor antagonist, 6,7-dinitroqui noxaline-2,3-dione. This suggests that the dopamine release induced by the delta-opioid agonist depends critically on the involvement of glu tamatergic transmission via NMDA receptors.