PCCG-IV INHIBITS THE INDUCTION OF LONG-TERM POTENTIATION IN THE DENTATE GYRUS IN-VITRO

The effects of two ligands with previously established high and select ive potency for metabotropic glutamate receptors (mGlu receptors) grou p Il have been investigated on the high frequency stimulation (HFS) in duced long-term potentiation of the field excitatory postsynaptic pote ntial (EPSP) in the dentate gyrus of the rat hippocampus in vitro. The ligands investigated were (2S,1'S,2'S,3'R)-2-(2 ''-carboxy-3'-phenylc yclopropyl)glycine (PCCG-IV) and (R,S)-alpha-methyl-4-tetrazolylphenyl glycine (MTPG). PCCG-IV (IO mu M) strongly inhibited the induction of long-term potentiation of the field EPSP by high frequency stimulation . MTPG (50 mu M) did not inhibit the induction of long-term potentiati on, but prevented the inhibition of long-term potentiation induction b y PCCG-IV. The inhibition of long-term potentiation induction by PCCG- IV is suggested to be due to an agonistic action on mGlu receptor grou p II, probably mGlu(3) receptor, as the inhibition of long-term potent iation can be reversed by the application of MTPG, a well-known select ive and potent antagonist of mGlu receptor group II. (C) 1997 Elsevier Science B.V.