Peptides derived from kainic acid as antagonists of N-methyl-D-aspartate-induced neuroexcitation in rat brain.

The effects of dipeptides and an amide chemically derived from kainic acid (KA) on the response of rat striatal slices to excitatory amino acids were studied. Some of the gamma-peptides of KA were found to antagonize the response to N-methyl-D-aspartate (NMDA) more than that to quisqualate and glutamate and not to have any effect on the response to kainate. The least potent antagonists among the tested compounds were the gamma-amide of KA and the peptides of KA with beta-alanine and gamma-aminobutyric acid, whereas the gamma-kainyl peptides of the alpha-amino acids glycine, tyrosine, glutamate and KA were more active. The latter are the best blockers of the response to NMDA among the tested compounds.