Modulation of NMDA receptor responsiveness by neurotransmitters, drugs and chemical modification.

The NMDA receptor is intimately involved an a wide range of pathophysiological processes in the mammalian brain, including epilepsy and ischemia-induced neurodegeneration. The widespread distribution of NMDA receptors places almost every area of the brain at risk from NMDA receptor over-activity. However, it is clear that the central nervous system can function effectively without imminent danger of self-destruction. The focus of this review is the processes that control NMDA receptor responsiveness in vivo. The review will cover the modulation of the receptor by Mg2+, glycine, Zn2+ and polyamines that is believed to occur by virtue of interaction with distinct ligand binding sites on the NMDA receptor complex. Studies suggesting a role for receptor phosphorylation and for redox modulation will be discussed. Finally, some evidence for indirect regulation of cellular responses to NMDA receptor activation by other neurotransmitters will be presented.