NMDA

NMDA (N-methyl-D-aspartic acid) is an amino acid derivative acting as a specific agonist at the NMDA receptor, and therefore mimics the action of the neurotransmitter glutamate on that receptor. In contrast to glutamate, NMDA binds to and regulates the above receptor only, but not other glutamate receptors.

NMDA is a water-soluble synthetic substance that is not normally found in biological tissue. It was first synthesized in the 1960's. NMDA is an excitotoxin; this trait has applications in behavioral neuroscience research. The body of work utilizing this technique falls under the term "lesion studies." Researchers apply NMDA to specific regions of an (animal) subject's brain or spinal cord and subsequently test for the behavior of interest, such as operant behavior. If the behavior is compromised, it suggests the destroyed tissue was part of a brain region that made an important contribution to the normal expression of that behavior.

Antagonists
Examples of antagonists of the NMDA receptor are APV, dextromethorphan, ketamine, phencyclidine (PCP), riluzole, memantine, and kynurenic acid, the only known endogenous antagonist. They are commonly referred to as NMDA receptor antagonists.

Forms
The structural formula of NMDA pictured above is written down as the neutral form. At physiological pH both carboxyl groups are deprotonated.