Abstract

Rotational and functional motor behavioral changes were studied in five MPTP lesioned chronic hemiparkinsonian Macaca nemestrinamonkeys after i.m. pramipexole, a predominant D₂ subfamily agonist. Pramipexole induced contraversive rotations in a dose-dependent manner with an optimal dose of 56 μg/kg for ∼2 to 4 hr after injection. Three different rating scales were used to determine drug-induced functional improvement. They included a monkey parkinsonism rating scale, volitional responses to fruit presentations, and number of hand movements that appeared volitional. A dose of 56 μg/kg of pramipexole produced functional improvements on hand disability, and on a parkinsonian rating scale for monkeys in a dose-dependent manner from 32 to 100 μg/kg. These doses produced an increase in significant hand movements in the affected (contralateral) as well as in the normal (ipsilateral) hand to the side of the brain lesion compared with 5% dextrose in water vehicle control. With a dose of 100 μg/kg, the therapeutic effects of pramipexole on hand movements were less than with 56 μg/kg, due to side effects such as scratching.