• Levodopa;
  • Parkinsonism;
  • MPTP;
  • Rhesus monkeys;
  • Rating scale


Quantitative measures for the severity of MPTP-induced parkinsonism and response to antiparkinsonian interventions in monkeys have been lacking. We carried out an oral levodopa dose-response study in two rhesus monkeys whose left hemiparkinsonism was induced by intracarotid administration of MPTP. A newly developed clinical rating scale of monkey parkinsonism showed a consistent dose-response relationship for levodopa over the dosage range of 50–3, 500 mg/day. Antiparkinsonian effects appeared at 200 mg/day and were optimal at 1,000–2,000 mg/day. Levodopa also reversed rotational behavior, improved movement times for both the impaired and opposite upper limb, and produced dyskinesias at high dosages. Thus, MPTP-induced hemiparkinsonism in monkeys closely resembles the human disease condition, is associated with sensitive response measures, and should prove valuable for assessing novel antiparkinsonian therapies.