INTERACTION OF ZINC WITH IONOTROPIC AND METABOTROPIC GLUTAMATE RECEPTORS IN RAT HIPPOCAMPAL SLICES

The actions of zinc on ionotropic and metabotropic glutamate receptors were studied using intracellular recording in acutely prepared adult rat hippocampal slices and in organotypic hippocampal slice cultures. In control Krebs, glutamate and non-N-methyl-D-aspartate (NMDA) agonist-induced responses were enhanced by zinc (25-300 muM). However, under conditions favouring NMDA receptor activation, zinc inhibited glutamate-and NMDA-induced responses. Metabotropic glutamate receptor-mediated responses activated in cultured slices by 1-amino-cyclopentane-1,3-dicarboxylate (IS,3R-ACPD) or by quisqualate, were reversibly inhibited by zinc (200 muM). These results indicate that zinc can inhibit responses induced by activation of metabotropic glutamate receptors and reaffirm that zinc has a differential effect on NMDA and non-NMDA receptors.