Macaca fasicularis monkeys and C-57 black mice were injected with N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in different injection regimes. 2. The performance of monkeys on a rapid alternating movement task was measured before, during and after drug injection. 3. The open field performance of C-57 black mice was assessed 0.5hr, 24hr and 7 days after the completion of the injection regime. 4. Only the monkey receiving the 2mg/kg dose over 8 days displayed progressive akinesia and muscular rigidity. 5. Only a very slight impairment of motor function was seen in the C-57 black mice 0.5hr after injection. 6. Fluorescent histochemical analysis revealed that while striatal depletion was severe in monkeys and mice, accumulation of amines was seen only in the brain tissue of the severely impaired monkey. 7. Degeneration-associated increases in amines are important in the aetiology of Parkinsonian-like motor impairment produced by selective neurotoxins across different species.
