Pathogenesis of Parkinson's disease.

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by degeneration of the nigrostriatal dopaminergic pathway and the appearance of cytoplasmic proteinaceous aggregates known as Lewy bodies. Studies of familial PD have uncovered rare causative mutations in genes, including alpha-synuclein. Mutations or oxidative modification of alpha-synuclein causes it to aggregate; alpha-synuclein is a major component of the Lewy body in both familial and sporadic PD. Biochemical analysis has implicated mitochondrial dysfunction in PD. Epidemiological studies indicate a role of exposure to pesticides, some of which are mitochondrial toxins. Mitochondrial dysfunction, resulting from genetic defects, environmental toxins, or a combination of the two, may cause alpha-synuclein aggregation and produce selective neurodegeneration through mechanisms involving oxidative stress and excitotoxicity. Efforts to better define PD pathogenesis should reveal novel therapeutic targets.