Glutamatergic pathways and receptors

Abstract

Glutamate is a major excitatory neurotransmitter in the vertebrate brain and is utilized at distinct synapses in the cerebellum. Glutamate released from presynaptic terminals binds to various types and classes of glutamate receptors at preand postsynapses. Glutamate receptors are classifi ed as metabotropic (mGluR) or ionotropic (iGluR). iGluRs function as glutamate-gated cation channels and are classifi ed pharmacologically as AMPA-, NMDA-, or kainite-types. AMPA receptors determine synaptic strength, whereas NMDA receptors induce synaptic plasticity. Kainate receptors play multiple roles in regulating synaptic transmission and plasticity. mGluRs are G protein-coupled receptors that modulate postsynaptic signaling by the type I mGluRs through Gq signaling and modulate glutamate release via the type II and III mGluRs acting via Gi/o signaling. Combinatory action among the glutamate receptors coordinates synaptic transmission and synaptic plasticity. Disruption of receptor activities causes various neurological disorders including epilepsy, mental retardation and neurodegenerative diseases, and controlling glutamate receptor activities is used as a therapeutic strategy for these disorders. This chapter covers topics of glutamate receptors and its auxiliary subunits.