[5][6][7] L-Glutamate is the major excitatory neurotransmitter in the central nervous system and activates both ionotropic and metabotropic glutamate receptors.

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

[5] A possible connection has been suggested between mGluRs and neuromodulators, as mGluR1 antagonists block adrenergic receptor activation in neurons.

By homologous recombination mediated gene targeting those mice became deficient in mGlu receptor 1 protein.

In the Morris watermaze test, an assay for learning abilities, those mice needed significantly more time to successfully complete the task.