Effect of kynurenic acid on the ischaemia-induced accumulation of glutamate in rat striatum.

We examined the effect of kynurenic acid, a broad spectrum antagonist of excitatory amino acid receptors, on striatal extracellular glutamate and aspartate accumulation induced by a 30 min forebrain ischaemia in rats. Kynurenic acid, given systemically (500 mg kg-1, i.p.) or administered in situ through the dialysis probe (10 mM), markedly depressed the ischaemia-induced increase in glutamate and aspartate concentrations. These results indicate that, during forebrain ischaemia, local glutamate receptors play a major role in glutamate and aspartate accumulation in the striatum. Ischaemia-induced increase in extracellular concentrations of these excitatory amino acids may be due in part to a positive glutamatergic feedback loop via activation of NMDA and/or non-NMDA receptors.