Definition of "MPTP"

(neurotoxicology) 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine: a byproduct of synthetic heroin, or MPPP, which causes parkinsonian symptoms in users; and a neurotoxin that degrades into MPP+ after crossing the blood-brain barrier, which causes a degradation of the dopaminergic neurons within the substantia nigra.