Interactions between dopamine D1 and D2 receptors in the model of thyrotropin-releasing hormone (TRH)-induced behaviour in rabbits.
The interactions between dopamine D1 and D2 receptors in the model of thyrotropin-releasing hormone (TRH)-induced behavioural excitation were assessed in adult male rabbits. As we had previously observed with the dopamine D1 receptor antagonist SCH 23390 (0.01 mg/kg i.v.), sulpiride (12 mg/kg i.v.), a dopamine D2 receptor antagonist, also significantly antagonized the scratching behaviour elicited by TRH (100 micrograms/10 microliters i.c.v.). Sulpiride (6 and 12 mg/kg i.v.) also induced marked grooming. SKF 38393 (10 mg/kg i.v.), a dopamine D1 receptor agonist, did not modify the TRH-induced scratching. However, LY 17155 (0.5 mg/kg i.v.), a dopamine D2 receptor agonist, significantly increased it. The potentiating effects of LY 171555 were completely antagonized by SCH 23390. These results demonstrate that a concomitant activation of both dopamine D1 and D2 receptors is required for the expression of TRH-induced scratching. They also suggest that scratching behaviour may be a D2-dependent, D1-enabled response. The involvement of dopamine D1 and D2 receptors on grooming behaviour is also discussed.
Pharmacology Department, Istituto Superiore di Sanità, Rome, Italy.
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D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects* / Q000502:physiology; D001552:Benzazepines / Q000494:pharmacology; D015259:Dopamine Agents / Q000494:pharmacology; D018492:Dopamine Antagonists; D004873:Ergolines / Q000494:pharmacology; D008297:Male; D019257:Quinpirole; D011817:Rabbits; D011954:Receptors, Dopamine / Q000378:metabolism*; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D013469:Sulpiride / Q000494:pharmacology; D013973:Thyrotropin-Releasing Hormone / Q000494:pharmacology*
D001552:Benzazepines; D015259:Dopamine Agents; D018492:Dopamine Antagonists; D004873:Ergolines; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D019257:Quinpirole; D013973:Thyrotropin-Releasing Hormone; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D013469:Sulpiride