Mitoquinone supplementation alleviates oxidative stress and pathologic outcomes following repetitive mild traumatic brain injury at a chronic time point

Traumatic brain injury (TBI) is a major cause of disability and death. Mild TBI (mTBI) constitutes similar to 75% of all TBI cases. Repeated exposure to mTBI (rmTBI), leads to the exacerbation of the symptoms compared to single mTBI. To date, there is no FDA-approved drug for TBI or rmTBI. This research aims to investigate possible rmTBI neurotherapy by targeting TBI pathology-related mechanisms. Oxidative stress is partly responsible for TBI/rmTBI neuropathologic outcomes. Thus, targeting oxidative stress may ameliorate TBI/rmTBI consequences. In this study, we hypothesized that mitoquinone (MitoQ), a mitochondria-targeted antioxidant, would ameliorate TBI/rmTBI associated pathologic features by mitigating rmTBI-induced oxidative stress. To model rmTBI, C57BL/6 mice were subjected to three concussive head injuries. MitoQ (5 mg/kg) was administered intraperitoneally to rmTBI+MitoQ mice twice per week over one month. Behavioral and cognitive outcomes were assessed, 30 days following the first head injury, using a battery of behavioral tests. Immunofluorescence was used to assess neuroinflammation and neuronal integrity. Also, qRT-PCR was used to evaluate the expression levels of antioxidant enzymes. Our findings indicated that MitoQ alleviated fine motor function and learning impairments caused by rmTBI. Mechanistically, MitoQ reduced astrocytosis, microgliosis, dendritic and axonal shearing, and increased the expression of antioxidant enzymes. MitoQ administration following rmTBI may represent an efficient approach to ameliorate rmTBI neurological and cellular outcomes with no observable side effects.