Chapter III Metabotropic glutamate receptors - immunocytochemical and in situ hybridization analyses

This chapter focuses on metabotropic glutamate receptors (mGluRs). These receptors are linked to several intracellular signal transduction mechanisms via G-protein and are implicated in diverse functions of the mammalian central nervous system (CNS). These functions include mediation of slow excitatory and inhibitory responses; regulation of calcium channels, potassium channels, and non-selective cation channels; inhibition and facilitation of transmitter release; induction of long-term potentiation and long-term depression; and regulation of neuronal development. Functional diversity of the metabotropic glutamate receptor is reflected in molecular diversity of receptor subtypes. The sites of action of mGluRs are widely found throughout different membrane compartments of neuronal and glial cells. The chapter reviews the differential subcellular localization of metabotropic glutamate receptors in relation to transmitter release sites. Patterns of subcellular localization of mGluRs are different among three subgroups: group I and III mGluRs are mainly localized to somatodendritic and axonal domains of neurons, respectively, while group II mGluRs are extensively localized to both domains as well as to glial cell processes.