title: Dopamine receptor antagonists fail to prevent induction of cocaine sensitization.
abstract: We investigated the ability of dopamine D1 and D2 class receptor antagonists to prevent the induction of behavioral sensitization to cocaine. The D2 receptor antagonist eticlopride failed to prevent the induction of cocaine sensitization. An intermediate dose of the D1 receptor antagonist SCH 23390 (0.1 mg/kg) appeared to prevent the induction of cocaine sensitization when tested after 3 days of withdrawal, but sensitization was clearly evident after 10 days of withdrawal. High doses of SCH 23390 alone produced supersensitivity to the behavioral effects of cocaine and to the inhibitory effects of D1 receptor agonists on nucleus accumbens neurons. Co-administration of eticlopride and SCH 23390 also failed to prevent the induction of cocaine sensitization. SCH 23390, but not eticlopride, prevented the expression of cocaine sensitization. We conclude that dopamine receptors are either not involved in the induction of cocaine sensitization or that redundant mechanisms exist to produce the same neuroadaptations.
authors.affiliation: Department of Neuroscience, Finch University of Health Sciences, Chicago Medical School, Illinois 60064-3095, USA.
authors.forename: F J
authors.initials: FJ
authors.lastname: White
authors.forename: A
authors.initials: A
authors.lastname: Joshi
authors.forename: T E
authors.initials: TE
authors.lastname: Koeltzow
authors.forename: X T
authors.initials: XT
authors.lastname: Hu
mesh_terms: D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D003042:Cocaine / Q000494:pharmacology*; D018492:Dopamine Antagonists / Q000494:pharmacology*; D065127:Dopamine D2 Receptor Antagonists; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology*; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011954:Receptors, Dopamine / Q000187:drug effects*; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors; D012457:Salicylamides / Q000494:pharmacology
chemical_list: D001552:Benzazepines; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D018765:Dopamine Uptake Inhibitors; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D012457:Salicylamides; D003042:Cocaine; C045989:eticlopride