7-Chlorokynurenate, an antagonist of the glycine binding site on the NMDA receptor, inhibits memory formation in day-old chicks (Gallus domesticus)

Unilateral intracranial injection into the left intermediate and medial hyperstriatum ventrale of 100 μmol · liter⁻¹ 7-chlorokynurenate, a highly selective antagonist of the glycine site on the N-methyl-d-aspartate receptor, prevents acquisition of memory for one-trial passive avoidance training in day-old chicks, in which the aversive stimulus is an unpleasant tasting substance, methyl anthranilate. Injections were given 30 min pretraining and the chicks were tested 30 min or 1 or 3 h post-training. Unilateral injections into the left intermediate and medial hyperstriatum ventrale were found to significantly block memory acquisition when birds were tested at all three time points, but unilateral injections in the right intermediate and medial hyperstriatum ventrale had no significant effect. Bilateral injections did not significantly increase the memory block. Injections of 7-chlorokynurenate given 5 min post-training failed to produce amnesia for the avoidance task when chicks were tested either 30 min or 1 h after training.