MPTP
n. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine: a byproduct of heroin synthesis that is used experimentally to induce symptoms of Parkinson’s disease in laboratory animals. It was discovered accidentally in 1976 when it was synthesized and injected by a recreational drug user who was attempting to produce an analog of meperidine. This individual developed acute symptoms of Parkinson’s disease, as did other users of the drug. Autopsy revealed massive degeneration of dopamine-containing neurons in the nigrostriatal tract. MPTP is not in itself neurotoxic (damaging to nerve tissue), but it is converted to the methylphenylpyridinium ion (MPP+), a potent neurotoxin at dopaminergic neurons, by the enzyme monoamine oxidase B.