An increasing amount of evidence suggests the existence of specific binding sites for psychotomimetic drugs from the opiate-benzomorphan and arylcyclohexylamine series. The sigma binding sites have preferential affinity for the dextrorotatory isomers of certain opiate benzomorphans, such as (+)SKF 10047, (+)cyclazocine and (+)pentazocine and also for some neuroleptics (e.g., haloperidol). The...