title: SCH-23390 antagonism of a D-2 dopamine agonist depends upon catecholaminergic neurons.
abstract: SCH-23390, a selective D-1 dopamine antagonist, was found to antagonize the locomotor stimulation induced by LY-171555, an action similar to that for haloperidol in control animals. However, this action of SCH-23390 was prevented in rats treated with 6-hydroxydopamine (6-OHDA) or with reserpine plus alpha-methyl-tyrosine pretreatment. These results indicate that the action of SCH-23390 to antagonize D-2 dopamine receptor actions is dependent upon functional catecholamine-containing neurons. In contrast to the lack of action of SCH-23390 to antagonize LY-171555 in 6-OHDA-treated rats, SCH-23390 blocked the locomotor stimulation induced by SKF-39393, a D-1 dopamine agonist, after this treatment. Thus, D-1 dopamine receptors are distinct from D-2 receptor sites and can exhibit a behavior similar to that observed when D-2 receptors are stimulated. These data suggest that D-1 receptor sites modulate D-2 dopamine receptor function through a mechanism dependent upon functionally intact catecholamine-containing neurons.
authors.forename: G R
authors.initials: GR
authors.lastname: Breese
authors.forename: R A
authors.initials: RA
authors.lastname: Mueller
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D000320:Adrenergic Fibers / Q000502:physiology*; D000818:Animals; D014150:Antipsychotic Agents / Q000494:pharmacology*; D001552:Benzazepines / Q000494:pharmacology*; D004873:Ergolines / Q000037:antagonists & inhibitors / Q000494:pharmacology; D006892:Hydroxydopamines; D008297:Male; D008781:Methyltyrosines / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects; D016627:Oxidopamine; D019257:Quinpirole; D051381:Rats; D011954:Receptors, Dopamine / Q000187:drug effects*; D017448:Receptors, Dopamine D2; D012110:Reserpine / Q000494:pharmacology; D019805:alpha-Methyltyrosine
chemical_list: D014150:Antipsychotic Agents; D001552:Benzazepines; D004873:Ergolines; D006892:Hydroxydopamines; D008781:Methyltyrosines; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D019257:Quinpirole; D019805:alpha-Methyltyrosine; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D012110:Reserpine; D016627:Oxidopamine