Accumulating evidence demonstrates that ferroptosis may be important in the pathophysiological process of traumatic brain injury (TBI). As a major hormone of the pineal gland, melatonin exerts many beneficial effects on TBI, but there is no information regarding the effects of melatonin on ferroptosis after TBI. As expected, TBI resulted in the time‐course changes of ferroptosis‐related molecules expression and iron accumulation in the ipsilateral cortex. Importantly, we found that treating with melatonin potently rescued TBI induced the changes mentioned above and improved functional deficits versus vehicle. Similar results were obtained with a ferroptosis inhibitor, liproxstatin‐1. Moreover, the protective effect of melatonin is likely dependent on melatonin receptor 1B (MT2). Although ferritin plays a vital role in iron metabolism by storing excess cellular iron, its precise function in the brain, and whether it involves melatonin's neuroprotection remain unexplored. Considering ferritin H (Fth) is expressed predominantly in the neurons and global loss of Fth in mice induces early embryonic lethality, we then generated neuron‐specific Fth conditional knockout (Fth‐KO) mice, which are viable and fertile but have altered iron metabolism. In addition, Fth‐KO mice were more susceptible to ferroptosis after TBI, and the neuroprotection by melatonin was largely abolished in Fth‐KO mice. In vitro siFth experiments further confirmed the results mentioned above. Taken together, these data indicate that melatonin produces cerebroprotection, at least partly by inhibiting neuronal Fth‐mediated ferroptosis following TBI, supporting the notion that melatonin is an excellent ferroptosis inhibitor and its anti‐ferroptosis provides a potential therapeutic target for treating TBI.

It has been reported that lysosomal proteases play important roles in ischemic and excitotoxic neuronal cell death. We have previously reported that cathepsin B expression increased remarkably after traumatic brain injury (TBI). The present study sought to investigate the effects of a selective cathepsin B inhibitor (CBI) [N-L-3-trans-prolcarbamoyloxirane-2-carbonyl)-L-isoleucyl-L-proline] on cell death and behavioral deficits in our model. We examined the levels of cathepsin B enzymatic activity and its expression by double labelling damaged cells in the brain slice with propidium iodide (PI) and anticathepsin B. The results showed an elevated enzymatic activity associated with TBI-induced increase in a mature form of cathepsin B, suggesting that cathepsin B may play a role in TBI-induced cell injury. PI was found to label cells positive for the neuronal-specific nuclear marker NeuN, whereas fewer GFAP-positive cells were labelled by PI, suggesting that neurons are more sensitive to cell death induced by TBI. Additionally, we found that pretreatment with CBI remarkably attenuated TBI-induced cell death, lesion volume, and motor and cognitive dysfunction. To analyze the mechanism of action of cathepsin B in the cell death signaling pathway, we assessed DNA fragmentation by electrophoresis, Bcl-2/Bax protein expression levels, Bid cleavage, cytochrome c release, and caspase-3 activation. The results imply that cathepsin B contributes to TBI-induced cell death through the present programmed cell necrosis and mitochondria-mediated apoptotic pathways.

Hydrogen sulfide (H2S), a novel gaseous mediator, has been recognized as an important neuromodulator and neuroprotective agent in the central nervous system. The present study was undertaken to study the effects of exogenous H2S on traumatic brain injury (TBI) and the underlying mechanisms. The effects of exogenous H2S on TBI were examined by using measurement of brain edema, behavior assessment, propidium iodide (PI) staining, and Western blotting, respectively. Compared to TBI groups, H2S pretreatment had reduced brain edema, improved motor performance and ameliorated performance in Morris water maze test after TBI. Immunoblotting results showed that H2S pretreatment reversed TBI-induced cleavage of caspase-3 and decline of Bcl-2, suppressed LC3-II, Beclin-1 and Vps34 activation and maintained p62 level in injured cortex and hippocampus post TBI. The results suggest a protective effect and therapeutic potential of H2S in the treatment of brain injury and the protective effect against TBI may be associated with regulating apoptosis and autophagy.

Objective To investigate changes of autophagy after traumatic brain injury (TBI) and its possible role. Methods Rat TBI model was established by controlled cortical injury system. Autophagic double membrane structure was detected by transmission electronic microscope. Microtubule-associated protein 1 light chain 3 (LC3) and Beclin 1 were also used to investigate the activation of autophagy post-TBI. Double labeling with LC3 and caspase-3, or Beclin 1 and Fluoro-Jade, to show the relationship between autophagy and apoptosis or neuron degeneration after TBI. Results An increase of autophagic double membrane structure was observed in early stage (1 h