Increased Nigral Iron Content and Alterations in Other Metal Ions Occurring in Brain in Parkinson's Disease

Levels of iron, copper, zinc, manganese, and lead were measured by inductively coupled plasma spectroscopy in parkinsonian and age-matched control brain tissue. There was 31-35% increase in the total iron content of the parkinsonian substantia nigra when compared to control tissue. In contrast, in the globus pallidus total iron levels were decreased by 29% in Parkinson's disease. There was no change in the total iron levels in any other region of the parkinsonian brain. Total copper levels were reduced by 34-45% in the substantia nigra in Parkinson's disease; no difference was found in the other brain areas examined. Zinc levels were increased in substantia nigra in Parkinson's disease by 50-54%, and the zinc content of the caudate nucleus and lateral putamen was also raised by 18-35%. Levels of manganese and lead were unchanged in all areas of the parkinsonian brain studied when compared to control brains, except for a small decrease (20%) in manganese content of the medial putamen. Increased levels of total iron in the substantia nigra may cause the excessive formation of toxic oxygen radicals, leading to dopamine cell death.