Emerging roles of GluN3-containing NMDA receptors in the CNS.

GluN3-containing NMDA receptors (GluN3-NMDARs) are rarer than the 'classical' NMDARs, which are composed solely of GluN1 and GluN2 subunits, and have non-conventional biophysical, trafficking and signalling properties. In the CNS, they seem to have important roles in delaying synapse maturation until the arrival of sensory experience and in targeting non-used synapses for pruning. The reactivation of GluN3A expression at inappropriate ages may underlie maladaptive synaptic rearrangements observed in addiction, neurodegenerative diseases and other major brain disorders. Here, we discuss current evidence for these and other emerging roles for GluN3-NMDARs in the physiology and pathology of the CNS.