Pharmacological tools for the investigation of metabotropic glutamate receptors (mGluRs): phenylglycine derivatives and other selective antagonists--an update.

Glutamate is known to produce many of its pre- and post-synaptic effects through interaction with at least three groups of G-protein-coupled metabotropic receptors. While molecular biological approaches have revealed a great deal about the nature of these receptors and their neuroanatomical localization, elucidation of their role in both physiological and pathological processes has been hampered by the lack of appropriate pharmacological agents. However, the situation is rapidly changing with the discovery of antagonist phenylglycine derivatives, and other compounds. Not only is it now possible to discriminate between the individual metabotropic glutamate receptor groups but, in several cases, between individual group members. The future development of potent and subtype-specific antagonists will greatly facilitate the advancement of our understanding of these receptors as well as providing the potential for novel therapeutic approaches in a variety of neuropathological states.