INHIBITION OF ENDOGENOUS DOPAMINE RELEASE IN AMPHIBIAN RETINA BY L-2-AMINO-4-PHOSPHONOBUTYRIC ACID (L-AP(4)) AND TRANS-2-AMINOCYCLOPENTANE-1,3-DICARBOXYLATE (ACPD)

The metabotropic glutamate receptor agonists 2-amino-4-phosphonobutyric acid (AP(4)) and trans-2-aminocyclopentane-1,3-dicarboxylate (ACPD) blocked light-stimulated dopamine release from Xenopus laevis retina. ACPD suppressed release in darkness but AP(4) did not. AP(4) blocked release stimulated in darkness by picrotoxin, a GABA-A receptor antagonist. The data suggest that regulation of dopamine release in Xenopus retina involves subpopulations of metabotropic glutamate receptors.