Despite
transferrin being the main circulating carrier of
iron in body fluids, and
iron overload conditions being known to worsen
stroke outcome through
reactive oxygen species (ROS)-induced damage, the contribution of blood
transferrin saturation (TSAT) to
stroke brain damage is unknown. The objective of this study was to obtain evidence on whether TSAT determines the impact of experimental
ischemic stroke on brain damage and whether
iron-free
transferrin (
apotransferrin, ATf)-induced reduction of TSAT is neuroprotective. We found that experimental
ischemic stroke promoted an early extravasation of circulating
iron-loaded
transferrin (
holotransferrin, HTf) to the ischemic brain parenchyma. In vitro, HTf was found to boost ROS production and to be harmful to primary neuronal cultures exposed to
oxygen and
glucose deprivation. In stroked rats, whereas increasing TSAT with exogenous HTf was detrimental, administration of exogenous ATf and the subsequent reduction of TSAT was neuroprotective. Mechanistically, ATf did not prevent extravasation of HTf to the brain parenchyma in rats exposed to
ischemic stroke. However, ATf in vitro reduced
NMDA-induced neuronal uptake of HTf and also both the
NMDA-mediated lipid peroxidation derived 4-HNE and the resulting neuronal death without altering Ca2+-
calcineurin signaling downstream the
NMDA receptor. Removal of
transferrin from the
culture media or blockade of
transferrin receptors reduced neuronal death. Together, our data establish that blood TSAT exerts a critical role in experimental
stroke-induced brain damage. In addition, our findings suggest that the protective effect of ATf at the neuronal level resides in preventing
NMDA-induced HTf uptake and ROS production, which in turn reduces neuronal damage.