| Secondary damage after traumatic brain injury is the main mechanism of chronic neuronal degeneration and neurological deficits, and now that oxidative stress is a key pathological aspects of secondary damage. Under normal physiological conditions, the body’s oxidative and anti-oxidation mechanism is in a state of dynamic balance. The balance state is destroyed after brain injury, the body shows oxidative stress. The treatment principle of traumatic brain injury is that inhibit the body’s main oxidative stress, while enhancing antioxidant capacity. In this study, we researched the neuroprotective function of NOX2 inhibitor apocynin and Nrf2 agonists tBHQ, investigated the relationship NOX2-Nrf2 after traumatic brain injury. We sure the research will provide new ideas for the clinical treatment of traumatic brain injury.Part I NADPH oxidase inhibition improves neurological outcome in experimental traumatic brain injuryPurpose. Traumatic brain injury (TBI) is a worldwide health problem with oxidative stress recognized as a major pathogenetic factor. The present experimental study was designed to explore the neuroprotective effect of NADPH oxidase (NOX) inhibitor, apocynin, on mouse TBI.Methods. Controlled cortical impact injury was performed in adult male mice randomly divided into four groups:sham, TBI, TBI+vehicle and TBI+apocynin treatment. apocynin (50 mg/kg) was injected intraperitoneally 30 min before TBI. The expression of NOX2 protein was investigated using immunoblotting techniques 1 and 24 hours after TBI. Neurological score was evaluated 24 hours after TBI. Blood-brain barrier disruption was detected by Evans blue extravasation and cortical apoptosis was analyzed by TUNEL assay. In addition tissue levels of malondialdehyde (MDA) were determined.Results. NOX2 expression increases rapidly following controlled cortical impact in male mice, with an early peak at 1h, followed by a second peak at 24 hours. Pre-treatment with the NOX inhibitor, apocynin markedly inhibited NOX2 expression. apocynin also attenuated MDA levels and TBI-induced blood brain barrier dysfunction. In addition apocynin also significantly attenuated TBI-induced neurological deficits and cortical apoptosis.Conclusion. Pre-treatment with apocynin effectively attenuates markers of cerebral oxidative stress after TBI, thus supporting the hypothesis of apocynin as a potential neuroprotectant and adjunct therapy for TBI patientsPart II Pre-treatment with tert-butylhydroquinone attenuates cerebral oxidative stress in mice after traumatic brain injuryPurpose:Traumatic brain injury (TBI) is a worldwide health problem, identified as a major cause of death and disability. Increasing evidence has shown that oxidative stress plays an important role in TBI pathogenesis. The antioxidant transcription factor known as nuclear erythroid 2-related factor 2 (Nrf2) is a known mediator in protection against TBI induced brain damage. The objective of this study was to test whether tert-butylhydroquinone (tBHQ), a novel Nrf2 activator, can protect against TBI-induced oxidative stress.Methods:Adult male ICR mice were randomly divided into three groups:(1) sham+ vehicle group; (2) TBI+vehicle group; and (3) TBI+tBHQ group. Closed head brain injury was applied using Feeney’s weight-drop method. We accessed the neurological outcome of mice at 24h post TBI, and subsequently measured protein levels of Nrf2 and the NOX2 subunit of NADPH oxidase, the concentration of malondialdehyde (MDA), superoxide dismutase (SOD) activity, and brain edema.Result:The NOX2 protein level was increased five-fold in the TBI+vehicle group, whereas pre-treatment with tBHQ markedly attenuated the NOX2 protein expression relative to that in the TBI+vehicle group. TBI increased Nrf2 formation by 5% compared with the sham group, whereas treatment with tBHQ further up-regulated the Nrf2 protein level by 12% compared with the sham group. The level of the oxidative damage marker MDA was reduced by 29% in the TBI+ tBHQ group compared with the TBI+ vehicle group, Moreover; pre-treatment with tBHQ significantly increased the antioxidant enzyme SOD activity. Administration of tBHQ also significantly decreased TBI induced brain edema and neurological deficits.Conclusion:Pre-treatment with tBHQ effectively attenuated markers of cerebral oxidative stress after TBI, thus supporting the testing of tBHQ as a potential neuroprotectant and adjunct therapy for TBI patients.Part Ⅲ Deletion of Nrf2 exacerbates oxidative stress after traumatic brain injury in micePurpose:Traumatic brain injury (TBI) is a worldwide public health and medical problem. Oxidative stress is recognized as an important contributing factor in the pathogenesis of TBI. The present study was designed to explore the anti-oxidative effect of Nuclear factor erythroid 2-related factor 2 (Nrf2) on brain damage induced by traumatic injury in a mouse model.Methods:Moderate weight-drop impact head injury was induced in adult male mice. The mice were randomly divided into four groups:Nrf2+/+ sham-operation, Nrf2-/-sham-operation, Nrf2+/+ TBI and Nrf2-/- TBI group. Neurological scores were evaluated 24 hours after TBI, followed by collection of the brain specimens. Brain edema was detected by the wet-dry ratio method. The expression of NOX2 protein in the brain specimen was investigated using Western blot analysis and immunohistochemical staining. In addition, malondialdehyde (MDA) level and superoxide dismutase (SOD) activity were evaluated in the brain tissues.Results:Twenty-four hours after TBI, Nrf2-/- mice were found to have significantly increased neurological deficits and brain edema, compared to Nrf2+/+ mice (P< 0.05). At the same time, we found that the expression of NOX2 protein, MDA level and SOD activity were significantly increased in Nrf2-/- mice after TBI compared to Nrf2+/+ mice (P< 0.05).Conclusion:We demonstrated that deletion of Nrf2 exacerbates oxidative stress after TBI in mice, suggesting that Nrf2 may play an important role in protecting brain injury after TBI, possibly by inhibiting oxidative stress. |
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