Levodopa-induced dyskinesia and response fluctuations in primates rendered parkinsonian with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP).

Six non-human primates received doses of MPTP sufficient to produce a severe parkinsonian syndrome. Levodopa therapy reversed parkinsonian features in all animals, but resulted in dose-dependent choreoathetoid movements of the lower limbs of 3, together with akathisia and dystonia in 2. 'End-of-dose deterioration' was common to all animals, although 'on-off' periods were only seen in 3. Preliminary observations using a clinical rating scale and automatic activity counters demonstrate that both the motor response to levodopa and the complications of therapy are readily quantifiable. We suggest that this is a useful experimental model for testing new strategies in the management of idiopathic Parkinson's disease, particularly with regard to the prevention of drug-induced involuntary movements.