Excitatory Glycine Responses of CNS Myelin Mediated by NR1/NR3 “NMDA” Receptor Subunits

NMDA receptors are typically excited by a combination of glutamate and glycine. Here we describe excitatory responses in CNS myelin that are gated by a glycine agonist alone and mediated by NR1/NR3 “NMDA” receptor subunits. Response properties include activation by d-serine, inhibition by the glycine-site antagonist CNQX, and insensitivity to the glutamate-site antagonist d-APV. d-Serine responses were abrogated in NR3A-deficient mice. Our results suggest the presence of functional NR1/NR3 receptors in CNS myelin.