BEHAVIORAL PHARMACOLOGY OF D-1-LIKE DOPAMINE-RECEPTORS - FURTHER SUBTYPING, NEW PHARMACOLOGICAL PROBES AND INTERACTIONS WITH D-2-LIKE RECEPTORS

1. There appears to exist a broad family of 'D-1-like' receptors in te rms both of differential coupling to distinct messenger/transduction m echanisms and of gene cloning, whose behavioural roles remain to be cl arified. 2. D-l receptors are now recognised to play a critical psycho pharmacological role in the regulation of unconditioned motor and nume rous other aspects of behaviour. 3. The adenylyl cyclase-inhibiting be nzazepine SK&F 83959 induces behavioural responses in rats that are si milar to those induced by the full efficacy cyclase-stimulating isochr oman A 68930 but not to those induced by its high efficacy partial ago nist benzazepine congener R-6-Br-APB; these data indicate roles for in dividual 'D-1-like' receptors in mediating distinct elements of dopami nergic behaviour. 4. The putative D-l autoreceptor agonist B-HT 920 an d the putative D-3 agonist 7-OH-DPAT demonstrate different behavioural profiles when given both alone and in combination with the selective 'D-1-like' antagonist BW 737C; D-3 receptors may participate in cooper ative/synergistic but not in oppositional 'D-1-like': 'D-2like' intera ctions. 5. Such interactions apparent at the level of behaviour are co mplemented by evidence for similar interactions at numerous alternativ e levels of function, though these may differ between rodent and prima te species. 6. A broader range of more selective agonists and antagoni sts, able to distinguish between individual members of the 'D-1-like' and of the 'D-2-like' receptor families are needed to clarify these is sues.