The relationship between intracellular free iron and cell injury in cultured neurons, astrocytes, and oligodendrocytes

Geraldine J. Kress, Kirk E. Dineley, Ian J. Reynolds

Research output: Contribution to journalArticle

112 Scopus citations

Abstract

Iron is an essential element for cells but may also be an important cytotoxin. However, very little is known about iron transport, redox status, or toxicity specifically inside cells. In this study, we exploited the sensitivity of fura-2 to quenching by ferrous iron (Fe2+) to detect intracellular free iron ([Fe2+]i) in neurons, astrocytes, and oligodendrocytes in primary culture. All cell types exposed to Fe2+ in the presence of the ionophore pyrithione rapidly accumulated Fe2+ to a similar extent. The heavy-metal chelators bipyridyl and N,N,N′,N′-tetrakis(2-pyridalmethyl)ethyl-enediamine rapidly reversed the increase in [Fe2+]i, whereas desferrioxamine had little effect. Interestingly, the Fe2+-mediated quenching of fura-2 fluorescence was reversed in a concentration-dependent manner by hydrogen peroxide. This was likely caused by the oxidation of Fe2+ to Fe3+ inside the cell. Acute exposure of cells to Fe2+ was only toxic when the metal was applied together with pyrithione, showing that Fe2+ is only toxic when elevated inside cells. Interestingly, only neurons and oligodendrocytes were injured by this elevation in [Fe2+]i, whereas astrocytes were unaffected, although [Fe2+]i was elevated to the same degree in each cell type. These studies provide a novel approach for detecting [Fe2+]i in a manner sensitive to the redox state of the metal. These studies also provide a model system for the study of the toxic consequences of elevated [Fe2+]i in neural cells.

Original languageEnglish
Pages (from-to)5848-5855
Number of pages8
JournalJournal of Neuroscience
Volume22
Issue number14
DOIs
StatePublished - Jul 15 2002
Externally publishedYes

Keywords

  • Astrocyte
  • Fluorescent dye
  • Intracellular iron
  • Neuron
  • Oligodendrocyte
  • fura-2

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