Quantitative localization of [³H]TCP binding in rat brain by light microscopy autoradiography

The anatomical localization of phencyclidine (PCP)/σ-opiate receptors in rat brain was determined by quantitative light microscopy autoradiography using the new ligand N-(1-[2-thienyl]cyclohexyl)[³H]TCP). TCP is a potent analog of PCP which possesses a higher affinity for PCP/σ-opiate receptor than those PCP itself. The higest of [³H]TCP binding was detected in the hippocampus. Intermediate levels were found in frontal cortex, striatum, amygdala and cerebellum. Specific [³H]TCP binding was undetectable in anterior commissure and corpus callosum. The distribution pattern of [³H]TCP binding sites is similar to the pattern obtained with [³H]PCP but more sharply defined. On the basis of its greater potency and specificity, [³H]TCP may prove superior to [³H]PCP as a molecular probe for the study of brain sigma opiate/phencyclidine receptors.