Characterization of specific sigma opiate/phencyclidine (PCP)-binding sites in the human brain

Specific [3H]phencyclidine (PCP)-binding studies were carried out in homogenates prepared from different regions of post-mortem human brains derived from subjects free of any neurological disease. Scatchard analysis revealed a single class of [3H]PCP-binding sites. Binding was found to be stereospecific i.e. markedly greater ability of the potent PCP agonist dexoxadrol to displace specifically bound 10 nM [3H]PCP as compared to its behaviorally inactive enantiomer levoxadrol. Stereospecific binding was abolished by preincubation of homogenate with trypsin or by heating the homogenate to 90 degrees C for 15 min. Various sigma opiates displaced specifically bound [3H]PCP binding in a rank order similar to that seen in rat brain. Thus a baseline has been established to enable future elucidation of the possible role of these sites in psychiatric illnesses.