In this progressive neurodegenerative disease there is increased deposition of iron within neuromelanin, specifically in the substantia nigra region. Gross cellular dysfunction occurs, with iron-induced oxidative stress accompanied by the destruction of the neuromelanin-containing neurons in the substantia nigra, locus coeruleus as well as C1 and C3 medullary group.
Significant decreases in glutathione content occur in specific brain regions of Parkinson's patients, not necessarily accompanied by increased levels of oxidized GSSH. Furthermore, since mitochondrial glutathione is one of the major defence mechanisms for removing hydrogen peroxide its depletion will potentiate oxidant-induced loss of mitochondrial function as well as promoting extramitochondrial activation of NFKB. The increase in haem oxygenase 1 in both Lewy bodies and PD nigra neurons (Schipper et al., 1998) will cause excessive cellular levels of haem-derived free iron and carbon monoxide and may contribute to the pathogenesis of PD.
Interestingly it has been noted that Indian vegetarians have a low incidence of Parkinson's disease in comparison with the Indian meat eaters, the Parsees. The reason for this difference has been suggested as the inhibition of iron absorption by the polyphenols that are present in high amounts in Indian spices. Further long-term studies of people with low iron status throughout their life time may give an indication as to whether decreasing iron intake may be beneficial in preventing the deposition of iron in the brain during the life time of an individual.
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