Behavioural evidence for the functionality of D-2 but not D-1 dopamine receptors at multiple brain sites in the 6-hydroxydopamine-lesioned rat.

Lisuride (D-2 agonist) and SKF 38393 (D-1 agonist) evoked characteristic circling and stereotyped orofacial movements when administered systemically or stereotaxically into the supersensitive caudate nucleus of unilaterally 6-hydroxydopamine-lesioned rats, which were respectively blocked by D-2 and D-1 antagonists. Lisuride induced similar behaviours from the accumbens, frontal cortex, pallidum, ventromedial thalamus, substantia nigra and periaqueductal grey, while SKF 38393 did not. Multiple brain sites may mediate D-2-induced (not D-1) behaviours following treatment with 6-hydroxydopamine.