Different sensitivities to MPTP toxicity in primate nigrostriatal and retinal dopaminergic systems: electrophysiological and biochemical evidence.

The influences of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) on dopamine content in the retina and the striatum of monkeys, as well as retinal responses to flash stimulation were studied. Dopamine depletion was observed in the striatum, while retinal dopamine content was similar to controls. The electroretinograms and the oscillatory potentials remained normal, even in monkeys presenting a severe Parkinsonian syndrome, in concordance with the biochemical data. It is proposed that the retinal dopaminergic system is less sensitive to the toxic effects of MPTP than the nigro-striatal pathway.