APORPHINE ENANTIOMERS - INTERACTIONS WITH D-1 AND D-2 DOPAMINE-RECEPTORS

  • 1 January 1984
    • journal article
    • research article
    • Vol. 25 (1), 18-23
Abstract
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. 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, the presence of an N-methylated tertiary amine in a molecule of appropriate configuration may confer dopamine receptor antagonist activity on the molecule.