Iron overload in the motor cortex induces neuronal ferroptosis following spinal cord injury

Abstract

Motor neuron death is supposed to result in primary motor cortex atrophy after spinal cord injury (SCI), which is relevant to poorer motor recovery for patients with SCI. However, the exact mechanisms of motor neuron death remain elusive. Here, we demonstrated that iron deposition in the motor cortex was significantly increased in both SCI patients and rats, which triggered the accumulation of lipid reactive oxygen species (ROS) and resulted in motor neuronal ferroptosis ultimately. While iron chelator, ROS inhibitor and ferroptosis inhibitor reduced iron overload-induced motor neuron death and promoted motor functional recovery. Further, we found that activated microglia in the motor cortex following SCI secreted abundant nitric oxide (NO), which regulated cellular iron homeostasis-related proteins to induce iron overload in motor neurons. Thus, we conclude that microglial activation induced iron overload in the motor cortex after SCI triggered motor neuronal ferroptosis and impeded motor functional recovery. These findings might provide novel therapeutic strategies for SCI.

Keywords: Ferroptosis; Iron overload; Lipid peroxidation; Motor cortex; Spinal cord injury.