Properties of the phencyclidine (PCP) receptors

[3H]Phencyclidine (PCP, Angel Dust) receptors have been characterized using a rat brain binding section technique. [3H]PCP labels a single class of site in rat brain (KD = 46 nM; Bmax = 10.5 fmol/slice). Ligand selectivity pattern strongly suggests that [3H]PCP binds to sites relevant for its pharmacological actions. Chronic PCP treatment (10 mg/kg/day for 14 days) decreases the number of sites (Bmax) for [3H]PCP and [3H]spiperone binding but not for [3H]dihydromorphine. These modifications could be related to the development of tolerance and dependence to PCP. Visualization of [3H]PCP binding sites shows high densities of receptors in cortical areas and hippocampus. Lower densities are observed in caudate-putamen, nucleus accumbens, and amygdala. Negligible quantities of receptors are seen in brain stem and over white matter. The presence of specific [3H]PCP binding sites in rat brain suggests the possible existence of an endogenous ligand for this unique receptor.