[5][6] L-glutamate is the major excitatory neurotransmitter in the central nervous system and activates both ionotropic and metabotropic glutamate receptors.

Glutamatergic neurotransmission is involved in most aspects of normal brain function and can be perturbed in many neuropathologic conditions.

The metabotropic glutamate receptors are a family of G protein-coupled receptors, that have been divided into 3 groups on the basis of sequence homology, putative signal transduction mechanisms, and pharmacologic properties.

Group II and III receptors are linked to the inhibition of the cyclic AMP cascade but differ in their agonist selectivities.

[6] This article incorporates text from the United States National Library of Medicine, which is in the public domain.