title: Attenuation of D-1 antagonist-induced D-1 receptor upregulation by concomitant D-2 receptor blockade.
abstract: The effect of chronic selective D-1 and/or D-2 dopamine receptor blockade on regional D-1 receptor binding was studied in rat brain following chronic treatment with the specific D-1 antagonist SCH 23390 and/or the predominantly D-2 antagonist haloperidol. D-1 receptor density and affinity were evaluated by quantitative autoradiography using 125I-SCH 23982. Chronic SCH 23390 treatment increased D-1 receptor density by 30 to 40% in the striatum, accumbens and tuberculum olfactorium; receptor affinity remained unchanged. Haloperidol had no effect on D-1 receptor Bmax or Kd values, although, when administered with SCH 23390, reduced the D-1 receptor upregulation induced by the D-1 antagonist in striatum and tuberculum olfactorium, but not in nucleus accumbens. These results may be attributable to D-1/D-2 dopamine receptor interactions occurring in the striatum and tuberculum olfactorium and may have implications for the prevention and treatment of drug-induced extrapyramidal disorders.
authors.affiliation: Experimental Therapeutics Branch, National Institutes of Neurological and Communicative Disorders and Stroke, Bethesda, MD 20892.
authors.forename: S A
authors.initials: SA
authors.lastname: Parashos
authors.forename: P
authors.initials: P
authors.lastname: Barone
authors.forename: I
authors.initials: I
authors.lastname: Tucci
authors.forename: T N
authors.initials: TN
authors.lastname: Chase
mesh_terms: D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D006220:Haloperidol / Q000494:pharmacology; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000502:physiology*
chemical_list: D001552:Benzazepines; D011954:Receptors, Dopamine; D006220:Haloperidol