title: Differential effects of dopamine D1 and D2 receptor antagonists on conditioned orienting behavior in the rat.
abstract: Brain dopamine (DA) systems are known to be important in regulation of behavior conditioned to appetitive stimuli. Nevertheless, despite a large body of evidence showing behavioral deficits in the operant conditioning paradigm produced by DA receptor blockade, there have been relatively few studies directly assessing behavioral changes in classical conditioning paradigm under this drug treatment. By employing an appetitive Pavlovian conditioning task, the present work investigated the effects of selective D1 and D2 receptor antagonists on the expression and acquisition of the conditioned orienting response (COR) and food-cup approach. SCH23390 (0, 0.05, and 0.10 mg/kg) and raclopride (0, 0.1, and 0.2 mg/kg) were administered via an intra-peritoneal route in a between-group design. Data from Experiment 1 showed that both SCH23390 and raclopride suppressed expression of the COR and food-cup approach, but only the impairment produced by raclopride reached a significant level. In Experiment 2, with SCH23390 being administered during the acquisition phase, the suppressed COR was completely restored in a subsequent (24 h later) drug-free session. In contrast, the suppressed COR in raclopride-pretreated groups was only partially restored. These findings support the view that the DA system plays a role in the neural substrates underlying this appetitive conditioning. In addition, D2 receptors are more likely involved in the modulation of learning process of the COR than D1 receptors.
authors.affiliation: Department of Psychology, National Cheng-Chi University, Taipei 116, Taiwan, ROC.
authors.forename: Yea-Huey
authors.initials: YH
authors.lastname: Chang
authors.forename: Ruey-Ming
authors.initials: RM
authors.lastname: Liao
mesh_terms: D000818:Animals; D001070:Appetitive Behavior / Q000187:drug effects / Q000502:physiology; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D001552:Benzazepines / Q000494:pharmacology*; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D018492:Dopamine Antagonists / Q000494:pharmacology*; D065127:Dopamine D2 Receptor Antagonists; D008297:Male; D020891:Raclopride / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors* / Q000502:physiology; D017448:Receptors, Dopamine D2 / Q000502:physiology
chemical_list: D001552:Benzazepines; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D020891:Raclopride