Role of D-1 and D-2 receptors in apomorphine-induced pecking in chicks.
The possible involvement of subtypes of dopamine (DA) receptors in pecking induced by apomorphine (APO) in chicks was studied. D-1/D-2 agonist APO dose-dependently induced pecking in chicks. The APO response was decreased in animals pretreated with either the D-2 receptor antagonist sulpiride or the D-1 receptor antagonist SCH 23390. The inhibitory effects of both antagonists were also dose dependent. The pecking induced by APO was completely inhibited in animals pretreated with a combination of SCH 23390 and sulpiride and was potentiated with reserpine. Single administration of D-2 agonist quinpirole or D-1 agonist SKF 38393 did not induced pecking, although quinpirole, but not SKF 38393 caused considerable response in reserpine or reserpine + alpha-methyl-p-tyrosine (AMPT)-treated animals. When quinpirole was administered with SKF 38393, a slight pecking response was shown. This was also potentiated in reserpine or reserpine + AMPT-treated chicks. The results may indicate that both D-1 and D-2 DA receptors are involved in pecking induced by APO, and reserpine treatment caused the sensitization of the D-2 receptors for the induction of pecking in chicks.
Department of Pharmacology, Medical School, University of Tehran, Iran.
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D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D001522:Behavior, Animal / Q000187:drug effects*; D001552:Benzazepines / Q000494:pharmacology; D002645:Chickens; D015259:Dopamine Agents / Q000494:pharmacology; D018492:Dopamine Antagonists; D004873:Ergolines / Q000494:pharmacology; D005260:Female; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology; D019257:Quinpirole; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D012110:Reserpine / Q000494:pharmacology; D013469:Sulpiride / Q000494:pharmacology; D014446:Tyrosine 3-Monooxygenase / Q000037:antagonists & inhibitors; D019805:alpha-Methyltyrosine
D001552:Benzazepines; D015259:Dopamine Agents; D018492:Dopamine Antagonists; D004873:Ergolines; D008781:Methyltyrosines; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D019257:Quinpirole; D019805:alpha-Methyltyrosine; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D013469:Sulpiride; D012110:Reserpine; D014446:Tyrosine 3-Monooxygenase; D001058:Apomorphine