Affiliations: Neuroscience Research Center, Medical Faculty
(Charité), Humboldt University Berlin, Germany | Research Institute of Environmental Medicine,
Düsseldorf, Germany
Note: [] Address for correspondence: Tilman Grune, Research Institute of
Environmental Medicine, Heinrich Heine University, Auf'm Hennekamp 50, 40225
Düsseldorf, Germany. Fax: +49 211 3389 222; E-mail:
Tilman.Grune@uni-duesseldorf.de
Abstract: Iron is one of the trace elements playing a key role in the normal
brain metabolism. An excess of free iron on the other hand is catalyzing the
iron-mediated oxygen radical production. Such a condition might be a harmful
event leading perhaps to serious tissue damage and degeneration. Therefore,
during evolution a complex iron sequestering apparatus developed, minimizing
the amount of redox-reactive free iron. However, this system might be severely
disturbed under pathophysiological conditions including hypoxia or anoxia. Since little is known about the non-transferrin-mediated iron
metabolism of the brain during anoxia/reoxygenation, we tested the ability of
the microglial cell line RAW 264.7 to take up iron independently of transferrin
under various oxygen concentrations. Microglial cells are thought to be the
major player in the maintenance of the extracellular homeostasis in the brain.
Therefore, we investigated the iron metabolism of microglial cells employing
radiolabeled ferric chloride. We tested the uptake of iron under normoxic,
anoxic and postanoxic conditions. Furthermore, the amount of ferritin was
measured by immunoblotting. We were able to show that iron enters the
microglial cell line in the absence of extracellular transferrin under
normoxic, anoxic and postanoxic conditions. Interestingly, the amount of
ferritin is decreasing in the early reoxygenation phase. Therefore, we concluded that microglia is able to contribute to the
brain iron homeostasis under anoxic and postanoxic conditions.
