Effects of subchronic exposures to concentrated ambient particles. VII. Degeneration of dopaminergic neurons in Apo E-/- mice.

This study reports that subchronic exposure of Tuxedo, NY concentrated ambient particulates (CAPs) produces neuropathological damage in the brains of Apo E-deficient mice (Apo E-/-). These genetically modified mice are characterized by elevated levels of oxidative stress (OS) in the brain. Microscopic examination of coronal sections of the brain, immunocytochemically stained for dopamineric neurons, indicated that neurons from the substantia nigral nucleus compacta were significantly reduced by 29% in CAPs-exposed Apo E-/- mice relative to air-exposed Apo E-/- controls. In addition, statistically significant increases (p < .05) in immunocytochemically stained astrocytes were noted. The dopaminergic neurons of the nucleus compact are specifically targeted in Parkinson's disease. The present study expands the systems affected by particulate matter to include the brain, and supports an environmental role for the development of neurodegeneration in OS-susceptible individuals.