Assessment of cocaine-like discriminative stimulus effects of dopamine D3 receptor ligands.

The highly selective dopamine D3 receptor ligand, (+)-PD 128907 4aR10bR-(+)-trans-3,4,4a,10b-tetrahydro-4-n-propyl-2H5H[4,3- b]-1,4- oxazin-9-ol), and other dopamine D3 receptor ligands, (+/-)-7-hydroxy-2-(N,N-di-n-propylamino)tetralin and (+)-7-hydroxy-2-(N,N-di-n-propylamino)tetralin, substituted for the discriminative stimulus effects of cocaine in rats, an animal model of subjective effects in humans. Substitution only occurred at doses that markedly decreased responding. These results suggest that dopamine D3 receptors may be involved in the subjective effects of cocaine, and therefore may be a target for the discovery of treatments for cocaine dependence.