NMDA receptors are ligand-gated cation channels that are activated by glutamate and glycine. They are distributed throughout the mammalian CNS, and play an important role in normal development and plasticity of the CNS, and likely in such specialized functions as memory and learning. Prolonged activation of these channels has been implicated in several pathophysiological conditions, such as stroke and epilepsy. Therefore, NMDA receptors represent relevant molecular targets for therapeutic agents in the treatment of stroke, epilepsy, head trauma, and pain (1 –3 ).