Effects of locally applied D-1 and D-2 receptor agonists and antagonists studied with brain dialysis.
The effect on dopamine (DA) release of D-1 and D-2 receptor agonists and antagonists applied locally in the caudate through a trans-striatal dialysis probe was studied in freely moving rats. D-2 agonists (LY 171555 and BHT 920) reduced DA release in a concentration-dependent manner. The same local application of haloperidol abolished the effect of 10 microM LY 171555 and BHT 920. A specific D-1 agonist, the catechol benzazepine SKF 38393, reduced DA release and this effect was not modified by systemic or local administration of the D-1 antagonist, SCH 23390, nor by the D-2 antagonist, haloperidol. In contrast, the non-catechol D-1 agonist, CY 208243, failed to modify DA release. Local application of the D-1 antagonist, SCH 23390, or of the D-2 antagonist, (-)-sulpiride, stimulated DA release in a concentration-dependent manner. The D-1 agonist, CY 20843, reversed the stimulatory effect of SCH 23390 but not that of (-)-sulpiride. It is concluded that D-1 and D-2 receptors located in the caudate control DA release separately in this area.
Imperato
A
A
Institute of Experimental Pharmacology and Toxicology, University of Cagliari, Italy.
Di Chiara
G
G
D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D001552:Benzazepines / Q000494:pharmacology; D001921:Brain / Q000187:drug effects / Q000502:physiology; D003956:Dialysis; D004298:Dopamine / Q000378:metabolism*; D015259:Dopamine Agents / Q000494:pharmacology*; D018492:Dopamine Antagonists; D004873:Ergolines / Q000494:pharmacology; D006220:Haloperidol / Q000494:pharmacology; D008297:Male; D019257:Quinpirole; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects* / Q000502:physiology; D013469:Sulpiride / Q000494:pharmacology
D001381:Azepines; D001552:Benzazepines; D015259:Dopamine Agents; D018492:Dopamine Antagonists; D004873:Ergolines; D011954:Receptors, Dopamine; D019257:Quinpirole; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; C024763:talipexole; D013469:Sulpiride; D006220:Haloperidol; D004298:Dopamine