α-Endopsychosin is a putative antagonist of the phencyclidine site of the NMDA receptor which was discovered in extracts of porcine brain and may also be endogenous in humans. The compound appears to be a peptide, but has yet to be purified and fully characterized.
See also Dimethyltryptamine (DMT) N-Acetylaspartylglutamic acid Ketamine Phencyclidine (PCP)
References