The benzazepine, SCH 23390, inhibits 3H-NPA binding in mouse brain in vivo.
The fact that SCH 23390, a selective dopamine (DA) D1 antagonist, blocks the effects of D2 agonists suggests a functional coupling of D1 and D2 receptors. Therefore, the binding of SCH 23390 to D2 receptors was investigated in vivo using 3H-N-n-propylnorapomorphine (NPA), a D2 agonist, and 3H-spiperone and 3H-raclopride, both D2 antagonists. SCH 23390 failed to inhibit 3H-spiperone or 3H-raclopride binding; however, SCH 23390 was relatively potent in inhibiting 3H-NPA binding. These results suggest that (some) antidopaminergic effects of SCH 23390 may result from antagonism of a D2 agonist conformation of the D2 receptor.
D000818:Animals; D001058:Apomorphine / Q000031:analogs & derivatives / Q000378:metabolism; D001552:Benzazepines / Q000378:metabolism / Q000494:pharmacology*; D001667:Binding, Competitive; D008297:Male; D051379:Mice; D020891:Raclopride; D011954:Receptors, Dopamine / Q000187:drug effects* / Q000378:metabolism; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D012457:Salicylamides / Q000378:metabolism; D013134:Spiperone / Q000378:metabolism
D001552:Benzazepines; D011954:Receptors, Dopamine; D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2; D012457:Salicylamides; D020891:Raclopride; D013134:Spiperone; C009074:N-n-propylnorapomorphine; D001058:Apomorphine