DIFFERENTIAL VULNERABILITY TO 1-METHYL-4-PHENYL-1,2,3,6-TETRAHYDROPYRIDINE OF DOPAMINERGIC AND CHOLINERGIC NEURONS IN THE MONKEY MESOPONTINE TEGMENTUM

Parkinson's disease is characterized by a loss of dopaminergic neurons in the substantia nigra and, in the most severe cases, by degeneratio n of mesopontine cholinergic neurons. In a monkey model of Parkinson's disease induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine we re port that, despite a severe loss of dopaminergic neurons, in the mesop ontine tegmentum cholinergic neurons are preserved in the same region. This suggests that the loss of mesopontine cholinergic neurons in par kinsonian patients may represent an end-stage degenerative process, th e cause of which may be independent of the mechanism of dopaminergic c ell death.