THE ROLE OF GROUP-II METABOTROPIC GLUTAMATE RECEPTORS IN HIPPOCAMPAL CA1 LONG-TERM POTENTIATION IN-VITRO

The role of group II metabotropic glutamate receptors (mGlu receptors) in mechanisms of long-term potentiation was investigated by analysis of excitatory postsynaptic field potentials of the CA1 region in rat h ippocampal slices. The application of the group II agonists (2S,1'S,2' S)-2-(carboxycyclopropyl) glycine (L-CCG-I) and (2S,1'R,2'R,3'R)-2-(2' ,3'-dicarboxycyclopropyl) glycine (DCG IV) resulted in a dose-dependen t reduction of long term potentiation in the concentration range 3-50 mu M. In contrast to the effects of group II agonists on long-term pot entiation, the group II antagonists RS)-alpha-methyl-3-carboxy-4-hydro xy-phenylglycine (M3C4HPG) and (RS)-alpha-methylserine-O-phosphate mon ophenyl ester (MSOPPE) elicited a dose-dependent enhancement of long-t erm potentiation (50-100 mu M or 20-50 mu M, respectively). We conclud e that group II mGlu receptors are not essential for the induction of long-term potentiation; however, they may be involved in feedback mech anisms in long-term potentiation. (C) 1998 Elsevier Science B.V. All r ights reserved.