title: Is clozapine selective for the dopamine D4 receptor?
abstract: Binding of 3H-spiperone and 3H-raclopride to membranes of cells stably-transfected with a human dopamine D2 receptor clone was investigated, as was that of 3H-spiperone to those stably-transfected with a human D4 receptor clone. 3H-spiperone and 3H-raclopride labeled the same number of sites in the D2 receptor preparation. The inhibition of binding by clozapine, spiperone, (-) eticlopride, haloperidol and the novel substituted benzamide 1192U90 was also investigated. Clozapine and 1192U90 showed greater inhibition of 3H-raclopride binding than 3H-spiperone binding to the D2 receptor. Comparison with inhibition of 3H-spiperone binding to the D4 receptor revealed that clozapine and 1192U90 displayed apparent selectivity (as assessed by Ki ratios) for the D4 receptor when compared with binding of 3H-spiperone, but not 3H-raclopride, to the D2 receptor.
mesh_terms: D001665:Binding Sites; D002462:Cell Membrane / Q000187:drug effects; D003024:Clozapine / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D006801:Humans; D020891:Raclopride; D017448:Receptors, Dopamine D2 / Q000187:drug effects*; D012457:Salicylamides / Q000494:pharmacology; D013134:Spiperone / Q000494:pharmacology
chemical_list: D018492:Dopamine Antagonists; D017448:Receptors, Dopamine D2; D012457:Salicylamides; D020891:Raclopride; D013134:Spiperone; D003024:Clozapine