Group III Metabotropic Glutamate Receptors (mGlu4, mGlu6, mGlu7, and mGlu8).

G protein-coupled group III metabotropic glutamate receptors (mGluRs) include four subtypes that are negatively coupled to adenylyl cyclase (mGluRs 4, 7, and 8) or positively to a cGMP phosphodiesterase (mGluR6). Typically, they exert inhibitory influences on neuronal activity. This chapter reviews the characteristics of group III mGluRs and their normal functions and role in nervous system disorders. The therapeutic potential of group III mGluRs resides in their antiepileptic (mGluRs 4 and 7), neuroprotective (mGluRs 4, 7, and 8), anti-parkinsonian (mGluRs 4 and 7), anxiolytic (mGluR4), and analgesic effects. However, possible side effects may need to be considered because group III mGluRs can inhibit normal synaptic transmission and memory processes, and mGluR6 is important for visual transmission. This chapter emphasizes that the analysis of the role of individual group III mGluR subtypes is required to determine their potential therapeutic value. [ABSTRACT FROM AUTHOR]