DOPAMINE-RECEPTORS MEDIATE DRUG-INDUCED BUT NOT PAVLOVIAN CONDITIONED CONTRALATERAL ROTATION IN THE UNILATERAL 6-OHDA ANIMAL-MODEL

Following Pavlovian conditioning treatment sessions with apomorphine, animals receiving the paired treatment showed substantial contralateral rotation when placed without drug into the test environment previously paired to the apomorphine (0.5 mg/kg) injection while animals in the unpaired control treatment showed only ipsilateral rotation. Subsequent tests with the D1 antagonist (SCH 23390), or the D2 antagonist (haloperidol) partially suppressed and the combined D1-D2 antagonists completely suppressed the apomorphine-induced response of contralateral rotation. The identical contralateral rotation response occurring as a Pavlovian conditioned response in the paired apomorphine treatment group was not attenuated by dopamine receptor blockade. In both paired and unpaired groups, the spontaneous ipsilateral rotation response was completely blocked. Thus, non-dopaminergic mechanisms mediate conditioned rotation whereas the drug-induced as well as the spontaneous rotation responses require stimulation of striatal dopamine receptors. © 1990.