Minocycline attenuates iron neurotoxicity in cortical cell cultures

Iron neurotoxicity may contribute to the pathogenesis of intracerebral hemorrhage (ICH). The tetracycline derivative minocycline is protective in ICH models, due putatively to inhibition of microglial activation. Although minocycline also chelates iron, its effect on iron neurotoxicity has not been reported, and was examined in this study. Cortical cultures treated with 10 μM ferrous sulfate for 24 h sustained loss of most neurons and an increase in malondialdehyde. Minocycline prevented this injury, with near-complete protection at 30 μM. Two other inhibitors of microglial activation, doxycycline and macrophage/microglia inhibitory factor, were ineffective. Oxidation of isolated culture membranes by iron was also inhibited by minocycline. Consistent with prior observations, minocycline chelated iron in a siderophore colorometric assay; at concentrations less than 100 μM, its activity exceeded that of deferoxamine. These results suggest that attenuation of iron neurotoxicity may contribute to the beneficial effect of minocycline in hemorrhagic stroke and other CNS injury models.