Apoptosis and autophagy in nigral neurons of patients with Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by progressive cell loss confined mostly to dopaminergic neurons of the substantia nigra. Several factors, including oxidative stress, and decreased activity of complex I mitochondrial respiratory chain, are involved in the degenerative process. Yet, the underlying mechanisms leading to dopaminergic cell loss remain elusive. Morphological assessment for different modes of cell death: apoptosis, necrosis or autophagic degeneration, can contribute significantly to the understanding of this neuronal loss. Ultrastructural examination revealed characteristics of apoptosis and autophagic degeneration in melanized neurons of the substantia nigra in PD patients. The results suggest that even at the final stage of the disease, the dopaminergic neurons are undergoing active process of cell death.