Chapter 16 - Glutamate receptors

Abstract

Glutamate receptors come in two types: ionotropic and metabotropic. The ionotropic receptors are ligand-gated ion channels. Traditionally, ionotropic glutamate receptors have been classified according to their preferred agonists into: AMPA (a-amino-3- hydroxy-5-methyl-4-isoxazoleproprionate), kainate and NMDA (N-methyl- D-aspartate) types. In contrast, NMDA receptor (NMDAR) activation results in slow synaptic potentials that are involved in various forms of activity-dependent synaptic plasticity. NMDARs also play important roles in brain development, learning and memory. This chapter considers the NMDA and non-NMDA glutamate receptors separately. The non-NMDA glutamate receptors are described, and the basic properties, structure, tissue distribution, topology, functional diversity, heteromization, mRNA editing, splicing, correlating structure and function are covered in detail. NMDA receptors, basic property, structure, topology, correlating structure and function, ligand-binding and modulation have also been discussed in the chapter. Glutamate channels and disease in mice showed defective Q/R editing causes neurodegeneration, which is explained in the next part of the chapter. The chapter concludes by describing Olivopontocerebellar degeneration where patients exhibit elevated levels of resting blood glutamate and abnormally high levels of glutamate following ingestion of the amino acid. It has, therefore, been suggested that the deficit in glutamate dehydrogenase may lead to a buildup of glutamate in the brain close to glutamate receptors and thereby, precipitate excitotoxic neuronal death.