HIGH-AFFINITY BINDING FOR PRAMIPEXOLE, A DOPAMINE D-3 RECEPTOR-LIGAND, IN RAT STRIATUM

Quantitative autoradiography of rat brain slices was carried out with eight concentrations of [H-3]pramipexole, a dopamine D-3 receptor-pref erring ligand. Saturation analysis revealed high affinity pramipexole binding (K-d = 0.2-0.4 nM) in the islets of Calleja, nucleus accumbens , olfactory tubercle, and anterior caudate. Since these affinities res emble pramipexole's affinity for the high affinity state of the rat do pamine D-3, but not D-2 receptors, it is possible that dopamine D-3 re ceptors have greater presence in caudate than has heretofore been appr eciated.