Antioxidant responses of cortex neurons to iron loading

Brain cells have a highly active oxidative metabolism, yet they contain only low to moderate superoxide dismutase and catalase activities. Thus, their antioxidant defenses rely mainly on cellular reduced glutathione levels. In this work, in cortical neurons we characterized viability and changes in reduced and oxidized glutathione levels in response to a protocol of iron accumulation. We found that massive death occurred after 2 days in culture with 10 mM Fe. Surviving cells developed an adaptative response that included increased synthesis of GSH and the maintenance of a glutathione-based reduction potential. These results highlight the fundamental role of glutathione homeostasis in the antioxidant response and provide novel insights into the adaptative mechanisms of neurons subjected to progressive iron loads.

Characterization of mitochondrial iron uptake in HepG2 cells

There is increasing evidence that accumulation of redox-active iron in mitochondria leads to oxidative damage and contributes to various neurodegenerative diseases, such as Friedreich's ataxia and Parkinson's disease. In this work, we examined the existence of regulatory mechanisms for mitochondrial iron uptake and storage. To that end, we used rhodamine B- [(1,10-phenanthrolin-5-yl)amino carbonyl ] benzyl ester, a new fluorescent iron-sensitive probe that is targeted specifically to the mitochondrion. We found that extracellular iron was incorporated readily into mitochondria in an apparently saturable process. Moreover, the rate of iron incorporation responded to the Fe status of the cell, an indication that the mitochondrion actively regulates its iron content.