The metabotropic glutamate receptors (mGluRs) are divided into 3 groups on the basis of sequence homology, putative signal transduction mechanisms, and pharmacological properties. Group II and group III mGluRs are linked to inhibition of the cyclic
AMP cascade, but differ in their agonist selectivity. mGluR7 is a member of Group III. Immunohistochemistry and in situ hybridization showed that mGluR7 expresses in various sites in the nervous system.