CPP, a new potent and selective NMDA antagonist. Depression of central neuron responses, affinity for [H]d-AP5 binding sites on brain membranes and anticonvulsant activity

Properties of a new potent antagonist acting selectively at N-methyl-D-aspartate (NMDA) type excitatory amino acid receptors are described. This compound, 3-((+/-)-2-carboxypiperazin-4-yl)propyl-1-phosphonic acid (CPP) is more potent than all previously reported NMDA antagonists in depressing mammalian spinal neuronal responses (cat and immature rat), in its affinity for 3H]D-AP5 (a radiolabelled NMDA antagonist) binding sites on rat brain membranes, and as an anticonvulsant in mice.