Comparisons between the in vitro binding of two substituted benzamides and two butyrophenones to dopamine-D2 receptors in the rat striatum.
The in vitro dopamine-D2 receptor binding profiles of two substituted benzamides (3H-sulpride and 3H-raclopride) and two butyrophenones (3H-spiperone and 3H-domperidone) were compared. 3H-Raclopride, 3H-domperidone and 3H-sulpride labelled approximately the same number of binding sites in the rat striatum, while 3H-spiperone labelled a higher number of binding sites. This latter finding was suggested to be due to the labelling of 5-HT2 receptors in addition to the dopamine-D2 binding sites since the labelling of these 5-HT2 receptors with 3H-spiperone could be avoided by the addition of the 5-HT2 receptor antagonist ketanserin. The inhibition constants (Ki) of the unlabelled compounds were similar to the Kd values obtained in the saturation analyses with 3H-raclopride, 3H-domperidone and 3H-sulpiride but were significantly higher when 3H-spiperone was used as radioligand. Addition of ketanserin to 3H-spiperone made the Ki values more similar to those obtained with the other radioligands. The implications of these findings in testing antidopaminergic activity is discussed.
D000818:Animals; D001549:Benzamides / Q000378:metabolism*; D002090:Butyrophenones / Q000378:metabolism*; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism*; D004294:Domperidone / Q000494:pharmacology; D066298:In Vitro Techniques; D007650:Ketanserin; D007700:Kinetics; D008297:Male; D010880:Piperidines / Q000494:pharmacology; D020891:Raclopride; D051381:Rats; D011919:Rats, Inbred Strains; D011954:Receptors, Dopamine / Q000187:drug effects / Q000378:metabolism*; D017448:Receptors, Dopamine D2; D012457:Salicylamides / Q000494:pharmacology; D013134:Spiperone / Q000494:pharmacology; D013469:Sulpiride / Q000494:pharmacology
D001549:Benzamides; D002090:Butyrophenones; D010880:Piperidines; D011954:Receptors, Dopamine; D017448:Receptors, Dopamine D2; D012457:Salicylamides; D020891:Raclopride; D013134:Spiperone; D004294:Domperidone; D013469:Sulpiride; D007650:Ketanserin