The actions of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in animals as a model of Parkinson's disease.
The ability of MPTP to induce persistent parkinsonism in man may provide a vital clue to the cause of the idiopathic disease. However, the peripheral administration of MPTP to rodent species only produces losses in brain dopamine content and damage to the nigrostriatal system in high doses and no persistent motor deficits have been observed. In contrast, in primates, the administration of MPTP rapidly induces a persistent parkinsonian syndrome accompanied by evidence for selective damage to the nigro-striatal dopamine containing system. Other neurotransmitter systems appear unaffected by MPTP treatment. The MPTP-treated primate responds to the administration of L-DOPA and other antiparkinsonian drugs and may provide a useful test-bed for the development of novel antiparkinsonian medication. Administration of MPTP to primates causes an accumulation of MPP+ in a variety of brain areas. The accumulation of MPP+ and the neurotoxic actions of MPTP in primates can be prevented by the prior administration of monoamine oxidase inhibitors. The ability of monoamine oxidase inhibitors to prevent MPTP toxicity is related to the metabolism of MPTP by monoamine oxidase B, probably extraneuronally in glia, to produce MPDP+ and subsequently MPP+. In rodent synaptosomal preparations MPP+ is a substrate for the dopamine uptake mechanism and so would be selectively accumulated in brain dopamine neurones. Administration of MPTP to animals results in the production of a partial model of idiopathic Parkinson's disease as it occurs in man. MPTP treatment produces the major symptoms of Parkinson's disease in primates but the pathology is limited to the nigro-striatal system, whereas in Parkinson's disease pathology is more widespread. Biochemical changes induced by MPTP again seem primarily limited to those induced by damage to the nigro-striatal dopamine containing system. MPP+ (or another metabolite of MPTP) may be responsible for the neurotoxicity of MPTP but not all neurones which accumulate products of MPTP metabolism are damaged. The nigro-striatal system may be peculiarly sensitive to the effects of MPTP.