CPPG is a potent antagonist of group II/III mGlu receptors. CPPG exhibits some selectivity (approximately 20 fold) for group III (IC50: 2.2 nM) over group II (IC50: 46.2 nM) mGlu receptors in the rat cerebral cortex.
L-APB is an effective and specific agonist for the group III mGluRs (EC50s: 0.13, 0.29, 1.0, 249 μM for mGlu4, mGlu8, mGlu6, and mGlu7 receptors, respectively).