title: Chronic antagonist treatment does not alter the mode of interaction of dopamine with rat striatal dopamine receptors.
abstract: Chronic treatment with the D1 and D2 dopamine receptor antagonists SCH 23390 (0.5 mg/kg) and haloperidol decanoate (25 mg/kg) caused an up-regulation in D1 and D2 receptor densities, respectively, with no change in KD. Dopamine (20 microM) interacted with both receptor subtypes in a mixed competitive/non-competitive manner, causing a reduction in ligand binding affinity and an apparent decrease in receptor density. In the presence of dopamine, both vehicle-treated and SCH 23390-treated striatal preparations showed a significant loss in affinity for 3H-SCH 23390 binding to D1 receptors and a decrease in D1 receptor density of approximately 26%. Similarly, dopamine caused a substantial loss in 3H-spiperone binding affinity to D2 receptors and a 46% decrease in Bmax in both vehicle-treated and haloperidol-treated membranes. Thus, receptor up-regulation does not appear to alter the mode of interaction of dopamine with rat striatal dopamine receptors.
authors.affiliation: Department of Pharmacology, University College Dublin, Belfield, Ireland.
authors.forename: K M
authors.initials: KM
authors.lastname: O'Boyle
authors.forename: K T
authors.initials: KT
authors.lastname: Gavin
authors.forename: N
authors.initials: N
authors.lastname: Harrison
mesh_terms: D000818:Animals; D001552:Benzazepines / Q000008:administration & dosage / Q000494:pharmacology*; D001667:Binding, Competitive; D003342:Corpus Striatum / Q000187:drug effects* / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D018492:Dopamine Antagonists; D006220:Haloperidol / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D011954:Receptors, Dopamine / Q000378:metabolism; D013997:Time Factors
chemical_list: D001552:Benzazepines; D018492:Dopamine Antagonists; D011954:Receptors, Dopamine; C033563:haloperidol decanoate; D006220:Haloperidol; D004298:Dopamine