Acidic amino acid antagonists of lateral perforant path synaptic transmission: agonist-antagonist interactions in the dentate gyrus.

Acidic amino acid antagonists were tested for their ability to block depolarizations produced by excitatory amino acids in the outer molecular layer of the dentate gyrus in hippocampal slices. 2-Amino-4-phosphonobutyrate (APB) and serine-O-phosphate (SOP), potent synaptic blockers of the lateral perforant path input to this system, are moderately selective antagonists of kainate and N-methyl-DL-aspartate depolarizations, but not depolarizations produced by L-glutamate, quisqualate, or serine-O-sulfate. N-Methyl-DL-aspartate responses were potently blocked by 2-amino-5-phosphonovalerate, but this antagonist is less potent than APB or SOP against the synaptic response.