The excitatory effects of glutamate (the major excitatory neurotransmitter) are mediated by the activation of ionotropic and metabotropic receptors. These receptors differ in their molecular, biochemical, physiological and pharmacological properties.

The ionotropic glutamate receptors are divided into three main categories: AMPA, NMDA (N-methyl-D-aspartate) and Kainate Receptors. NMDA receptors have a pivotal role in the regulation of synaptic function in the central nervous system. They are molecularly composed of three different subunits: NR1, NR2 and NR3 which can undergo alternative splicing.