Dopaminergic cell loss in Parkinson’s disease

The overall level of atrophy of brain tissue does not seem to differ between patients with PD and age-matched controls.² However, by the time a patient with PD develops motor symptoms, they will have suffered a moderate-to-severe loss of neuromelanin-pigmented, dopamine-producing neurons in the substantia nigra, which causes a severe depletion of dopamine in the striatum.^2,3 The loss of dark pigmentation in the substantia nigra is easily visible in the pale, post-mortem brain tissue of affected individuals (see slide).²

References:
1.Michel PP, Hirsch EC, Hunot S. Understanding dopaminergic cell death pathways in Parkinson disease. Neuron 2016; 90 (4): 675–691.

2.Halliday GM, Murphy K, Cartwright H. Pathology of Parkinson’s disease. In: Wolters & Baumann (eds). Parkinson Disease and Other Movement Disorders. VU University Press, 2014.

3.Shulman JM, de Jager PL, Feany MB. Parkinson’s disease: genetics and pathogenesis. Annu Rev Pathol 2011; 6: 193–222.