Behavioral and biochemical stereoselectivity of sigma opiate/PCP receptors.

The relative potencies of the stereoisomers of ketamine, N-allylnormetazocine and cyclazocine were determined at mu opiate and sigma opiate/phencyclidine (PCP) receptors in vitro in rat brain homogenates, as well as in a discriminative stimulus behavioral paradigm in rats trained to discriminate PCP from saline. In all cases the in vivo and in vitro data were in agreement. The (+)-isomers of N-allylnormetazocine and cyclazocine are highly specific sigma opiate/PCP ligands.