Pharmacological and autoradiographic discrimination of sigma and phencyclidine receptor binding sites in brain with (+)-[3H]SKF 10,047, (+)-[3H]-3-[3-hydroxyphenyl]-N-(1-propyl)piperidine and [3H]-1-[1-(2-thienyl)cyclohexyl]piperidine.
The benzomorphan opioid, SKF 10,047, is the prototypical agonist for the sigma receptor. In this study, pharmacological and autoradiographic analyses reveal that (+)-[3H]SKF 10,047 labels two sites in brain: a high affinity site resembling the sigma receptor and a second site, labeled with lower affinity by (+)-[3H] SKF 10,047, similar to the phencyclidine (PCP) receptor. The drug specificity of the high affinity site for (+)-[3H]SKF 10,047 resembles that of the putative sigma receptor labeled with (+)-[3H]-3-[3-hydroxyphenyl]-N-(1-propyl)piperidine [(+)-[3H]-3-PPP], being potently inhibited by (+)-3-PPP, haloperidol and (+/-)-pentazocine, and demonstrating stereoselectivity for the (+)-isomer of SKF 10,047. In contrast, these drugs are weak in inhibiting binding of (+)-[3H]SKF 10,047 to the low affinity site, whereas PCP analogs, such as 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP) and 1-[1-(m-aminophenyl)cyclohexyl]piperidine (m-NH2-PCP), are potent inhibitors. No stereoselectivity for the isomers of SKF 10,047 is noted at the low affinity binding site. Autoradiographic localizations of high affinity (+)-[3H]SKF 10,047 binding sites closely resemble those of (+)-[3H]-3-PPP labeled sites with high levels of binding in the hippocampal pyramidal cell layer, hypothalamus, pontine and cranial nerve nuclei and cerebellum. By contrast, low affinity (+)-[3H]SKF 10,047 sites are most abundant in nonpyramidal layers of the hippocampus, the cerebral cortex and thalamic nuclei, similar to the distribution of [3H]TCP labeled PCP receptors.
D000818:Animals; D001345:Autoradiography; D001667:Binding, Competitive; D001923:Brain Chemistry; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D010620:Phenazocine / Q000031:analogs & derivatives* / Q000378:metabolism; D010622:Phencyclidine / Q000031:analogs & derivatives* / Q000378:metabolism; D010880:Piperidines / Q000378:metabolism*; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D017981:Receptors, Neurotransmitter / Q000032:analysis*; D011957:Receptors, Opioid / Q000032:analysis*; D017478:Receptors, Phencyclidine; D017480:Receptors, sigma; D013237:Stereoisomerism
D010880:Piperidines; D017981:Receptors, Neurotransmitter; D011957:Receptors, Opioid; D017478:Receptors, Phencyclidine; D017480:Receptors, sigma; C012134:SK&F 10047; C012058:tenocyclidine; C026539:preclamol; D010620:Phenazocine; D010622:Phencyclidine