Aporphine enantiomers. Interactions with D-1 and D-2 dopamine receptors

ME Goldman and JW Kebabian

The R(-) and the S(+) enantiomers of apomorphine (APO) and N-n-propyl norapomorphine (NPA) interact with both the D-1 and the D-2 dopamine receptors. R(-)-APO, as well as R(-)- and S(+)-NPA, stimulates the D-1 dopamine receptor in carp retina; S(+)-APO blocks this dopamine receptor. Similarly, R(-)-APO, as well as R(-)- and S(+)-NPA, stimulates the D-2 dopamine receptor in the intermediate lobe of the rat pituitary gland; S(+)-APO blocks the intermediate lobe D-2 receptor. The interactions between these aporphine enantiomers and the D-1 and the D-2 dopamine receptors exemplify several manifestations of the previously described "n-propyl phenomenon." Because S(+)-APO is distinguished from the other tested aporphines by its ability to antagonize either the D-1 or the D-2 dopamine receptors, it is hypothesized that the presence of an N-methylated tertiary amine in a molecule of appropriate configuration can confer dopamine receptor antagonist activity to the molecule.

Volume 25, Issue 1, pp. 18-23, 01/01/1984
Copyright © 1984 by American Society for Pharmacology and Experimental Therapeutics

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