The Neuroprotective Mechanisms Of Aucubin On Experimental Traumatic Brain Injury In Mice

BackgroundTraumatic brain injury(TBI)is a major public health problem in modern society,which has caused severe neurological damage and heavy economic burden to patients.As one of the characteristic pathological mechanisms of secondary brain injury,oxidative stress has been widely concerned.It activates or intensifies aseptic inflammatory response and induces neuronal apoptosis.Nuclear factor erythroid 2-related factor 2(Nrf2)is an important transcription factor to regulate cellular oxidative stress.Aucubin(Au),as an herbal extract,has anti-inflammatory and antioxidant neuroprotective properties.However,its molecular mechanism remains still unclear.Therefore,this experiment intends to explore its potential molecular mechanisms in TBI model.ObjectiveWe are attempting to investigate the neuroprotective effects of Au on TBI mice and the potential molecular mechanisms.Methods1.Different doses of Au were added to the oxidative stress model of primary cortical neurons.After 12 hours,neurons were collected for Western blot,immunofluorescence staining and DCFH-DA reactive oxygen species staining.2.The TBI model was established by Flierl's method.After different doses of Au were administered,the TBI mice were evaluated for neurological functions(modified neurological severity score,rotarod test and Morris Water Maze test)and measured for brain water content at a specified time.3.After intraperitoneal injection of different doses of Au,the TBI mice were sacrificed,and the tissues were collected for Western blot,quantitative real-time polymerase chain reaction(q-PCR),TUNEL staining,Nissl staining,immunofluorescence staining,immunohistochemistry staining and enzyme-linked immunosorbent assay(ELISA).4.After injecting lentivirus loaded with Nrf2shRNA into the lateral ventricle of mice,TBI modeling was performed.TBI mice with Au treatment were sacrificed,and the tissues were collected for Western blot.Results1.Au promotes the intracellular Nrf2 transfer to the nucleus,increased the intracellular antioxidant enzyme protein levels,decreased the intracellular apoptosis-related protein levels,and inhibited the generation of intracellular reactive oxygen species.2.Au reduced the brain edema caused by TBI,and improved the impaired neurologic functions and cognitive functions of TBI mice.3.Au promoted Nrf2 into nucleus of cortical neurons,increased the antioxidant enzymes in plasma and cortical tissues,reduced Malonaldehyde in plasma and cortical tissues,inhibited the expression of apoptosis related proteins in cortical tissues,and alleviates the damage of cortical neurons in TBI mice.4.Nrf2 knockdown weakened Nrf2 transfer into the neuronal nucleus,reduced the antioxidant enzyme protein levels and increased the apoptosis-related protein levels in TBI mice with Au treatment.In addition,Nrf2 knockdown in TBI mice blunted the effects of blocking HMGB1-TLR4-MyD88 inflammatory pathway by Au.ConclusionAu provides a neuroprotective effect in TBI mice model by inhibiting oxidative stress and inflammatory responses;the mechanisms involve triggering Nrf2-induced antioxidant system.