ABSTRACT
NMDA receptors (NMDARs), a subtype of ionotropic glutamate receptors, mediate the vast majority of excitatory neurotransmission in the central brains of vertebrates. NMDARs form heteromeric complexes usually comprised of a principal NR1 subunit and various NR2 subunits.1,2 The NMDAR channel is highly permeable to Ca2+ and Na+, and its opening requires simultaneous binding of glutamate and postsynaptic membrane depolarization.1,3,4 Once activated, the NMDAR channel allows calcium influx into postsynaptic cells, where calcium triggers a cascade of biochemical events resulting in synaptic changes. NMDARs play diverse roles in normal central nervous system activity and development including regulation of synaptic development and function, and refinement of synaptic connections with experience and synaptic plasticity. NMDARs have also been widely investigated as targets for pharmacological management of seizures, pain, and a variety of neurological disorders including Schizophrenia, Parkinson’s, Alzheimer’s, and Huntington’s diseases.2,5-14
Various studies in invertebrates suggest the existence of functional NMDA-like receptors and their requirement for synaptic and behavioral plasticity.15-37 This chapter highlights the recent characterization of Drosophila NMDARs,25,29-33 with emphasis on their physiological role during memory processing after Pavlovian olfactory conditioning-a well-defined and widely used elemental learning paradigm.38
