Dopamine receptor subtypes and formalin test analgesia.
The role played by dopamine D1 and D2 receptors in formalin test analgesia was explored by challenging D-amphetamine- and morphine-induced analgesia with mixed and selective D1 and D2 antagonists, and by examining the relative analgesic activity of mixed and selective D1 and D2 agonists. The mixed D1/D2 dopamine antagonist cis-flupenthixol (0.5 mg/kg), the D2 antagonist pimozide (0.5 mg/kg), and the D1 antagonist SCH 23390 (0.1 mg/kg) attenuated both D-amphetamine and morphine analgesia. The mixed D1/D2 agonist apomorphine and the selective D2 agonist quinpirole produced dose-dependent analgesia while the selective D1 agonist SKF 38393 was without effect. These data suggest that D1 receptors play an "enabling" role in D2 receptor-mediated analgesia in the formalin test.
Department of Psychology, McGill University, Montreal, Quebec, Canada.
M J
MJ
Morgan
K B
KB
Franklin
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine / Q000494:pharmacology; D000698:Analgesia; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology; D003913:Dextroamphetamine / Q000494:pharmacology; D015259:Dopamine Agents / Q000494:pharmacology; D018492:Dopamine Antagonists; D004305:Dose-Response Relationship, Drug; D004873:Ergolines / Q000494:pharmacology; D005475:Flupenthixol / Q000494:pharmacology; D005557:Formaldehyde; D008297:Male; D009020:Morphine / Q000494:pharmacology; D010146:Pain / Q000139:chemically induced / Q000503:physiopathology*; D010868:Pimozide / Q000494:pharmacology; D019257:Quinpirole; D051381:Rats; D011954:Receptors, Dopamine / Q000187:drug effects*; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2
D001552:Benzazepines; D015259:Dopamine Agents; D018492:Dopamine Antagonists; D004873:Ergolines; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D005557:Formaldehyde; D010868:Pimozide; D019257:Quinpirole; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D009020:Morphine; D005475:Flupenthixol; D001058:Apomorphine; D003913:Dextroamphetamine