2-Amino-7-Phosphonoheptanoic Acid (AP7)

AP-7 is a selective NMDA receptor (NMDAR) antagonist that competitively inhibits the glutamate binding site and thus activation of NMDAR. It has anticonvulsant effects. AP-7 functions specifically as a NMDA recognition site blocker, in contrast with 7c-KYNA which acts as a glycine site modulation blocker. AP-7 injected directly into the dorsal periaqueductal grey (DPAG) of rats produced an anxiolytic effect, whereas direct injection outside of the DPAG did not elicit anxiolytic effects. This suggests that a portion of systemically taken NMDA antagonist’s anxiolytic effects comes from the DPAG region of the brain, at least in rats. The DPAG of the brain is thought to deal with fear-like defensive behavior via NMDA and glycine B receptors. These excitatory glutamate receptors work with the inhibitory GABA receptors to achieve equilibrium in the DPAG of the brain.