Effect of Nrf2 on brain injury induced by hydraulic shock via regulation of mitophagy and apoptosis

The specific protective mechanism of mitophagy and Nrf2 in brain injury has not been fully clarified. This study aimed to reveal the effect of Nrf2 on hydraulic shock brain injury in mice, and explore its possible mechanism. Twenty-four Nrf2 knockout (Nrf2-/-) and wild-type mice (WT) of C57BL/6J were randomly divided into two groups: control group (C) and brain injury group (TBI). Hematoxylin-eosin staining (HE) assay was used for the histomorphological observation. The apoptotic state of brain tissue was detected by TUNEL. Mechanical damage in vitro models of glial cells were prepared. The wild-type (WT) and Nrf2 knockout (KO) mice were constructed to investigate the changes of mitophagy and apoptosis-related indicators by Western blotting. The experimental results showed that 24 h after TBI, the tissue structure was highly porous, the cells were highly edema, the neuronal space increased significantly, the neuron degeneration, and the cell vacuolation was obvious. Meanwhile, the number of apoptotic cells and the apoptosis rate of glial cells increased significantly. After injury, the relative expression of Parkin, Pink, Beclin and LC-3II proteins were significantly decreased in all mice. The protein expressions of Caspase3 and Caspase12 were significantly increased. However, in the TBI group, KO mice were more impaired than WT mice. In conclusion, Nrf2 plays a protective role by promoting mitophagy to inhibit apoptosis in the process of brain injury caused by hydraulic shock in mice, which provides a new idea for the effective treatment of brain injury.