2-Methyl-1,2,3,4-tetrahydroisoquinoline does dependently reduce the number of tyrosine hydroxylase-immunoreactive cells in the substantia nigra and locus ceruleus of C57BL/6J mice.

2-Methyl-1,2,3,4-tetrahydroisoquinoline (2-MTIQ) was administered chronically to C57BL/6J mice. Light and electron microscopic examinations revealed atrophic neurons restricted to the central portion of the substantia nigra pars compacta (SNc) and pars lateralis as well as a reduction in tyrosine hydroxylase immunoreactivity, which showed a significant inverse correlation with the dose administered in the SNc. 2-MTIQ may be a candidate endogenous or environmental factor that induces parkinsonism.