Effect of the glycine modulatory site of the N-methyl-D-aspartate receptoron synaptic responses in kitten visual cortex

In visual cortical slices taken from kittens, the administration of D-serin e, an agonist of the N-methyl-D-aspartate receptor complex, significantly e nhanced synaptically evoked responses using field potential recordings in l ower layer II/III. Expression of normally appearing long-term potentiation (LTP) took place in the presence of the agonist during high-frequency stimu lation (HFS). The administration of an antagonist of this receptor, 7-chlor o-kynurenic acid (7-Cl KY) alone had no appreciable effect on low-frequency synaptic transmission while HFS failed to induce LTP. Combined administrat ion of D-serine and 7-Cl KY resulted in no alteration of low-frequency syna ptic transmission, although expression of LTP was normally obtained. These results suggest that in visual cortex of kittens, the availability of this glycine binding site of the NMDA receptor is necessary for the expression o f LTP. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.