The Neuroprotective Effects Of NBP Against Secondary Brain Injury In Models Of Traumatic Brain Injury

Background:Traumatic brain injury(TBI)is a common disease in neurosurgery,with high disability and high mortality,especially in patients with severe craniocerebral injury.Oxidative stress play an important role in the process of brain injury,and nuclear factor E2 related factor 2(nuclear factor erythroid 2-related factor 2,Nrf2)is an important transcription factors regulating cell oxidative stress.NBP(dl-3-n-butylphthalide)has been found to have a clear protective effect on various nervous system diseases.Therefore,we established a model of traumatic brain injury in mice to explore whether the use of NBP after traumatic brain injury plays a neuroprotective role and its molecular mechanism in this experiment.Objective:The goals of these studies were to evaluate the neuroprotective effects of NBP on TBI mice and the role of NBP on Nrf2-ARE signal pathway activation.Also the relationship between NBP and oxidative stress,inflammation and,autophagy would be discussed in order to provide a basis for clinical treatment of TBI.Methods:(1)Adult ICR mice were randomly assigned to four groups:sham group,TBI group,TBI+V(vehicle)group,and TBI+NBP group.The model of TBI used in the present study was based on weight-drop model.NBP(100 mg/kg)was administered via an intraperitoneal(i.p.)injection at 1h post TBI.(2)Observing the effects of NBP on neurological function at 1h,24h and 72h and brain edema at 24h following TBI.(3)Using Western blot to measure expression of the NQO-1,HO-1,and Nrf2.(4)Nissl staining was used to measure the degeneration of neurons and TUNEL method was used to detect the apoptosis of neurons around the lesion.(5)The localization of Nrf2 were detected by NeuN and Nrf2 double immunofluorescence,and LC3 and NeuN were also used to observe via immunofluorescence double immunofluorescence method.The number and activation of microglial cells were detected by IBA-1 immunofluorescence.(6)The mRNA level of NQO-1 and HO-1 were measure by qRT-PCR.(7)The levels of MDA,GPx and SOD,indicators of lipid peroxidation and antioxidant enzyme activity,were measured in brain tissue and ELISA was used to detect the protein content of inflammatory cytokines(TNF-a and IL-1?).Results:After trauma brain injury,the score of neurological function was lower than that of the sham group,and the level of cerebral edema and oxidative stress increased significantly,accompanied with increased microglia activation,increased protein involved in inflammation,elevated degeneration of neuron,and autophagy body,while the number of neuron is reduced.There was no statistical difference between TBI group and TBI+V group,but the above damage indexes can be reversed after administration with NBP.NBP promoted the translocation of Nrf2 protein from the cytoplasm to the nucleus,increased the expressions of Nrf2-ARE pathway-related downstream factors,including hemeoxygenase-1(HO-1)and quinone oxidoreductase 1(NQO-1).Conclusion:In the model of traumatic brain injury in mice,NBP drugs also have a protective effect on brain.The possible mechanism is as follows:1,NBP can reduce cerebral edema,decrease oxidative stress,improve the neurological function score of mice,which may be associated with the activation of Nrf2-ARE signaling pathway;2,NBP can inhibit the activation of microglia cells after trauma,reduce the release of inflammatory cytokines,alleviate the loss of neuronal degeneration,and improve neurological dysfunction;3,NBP can alleviate the loss of neuronal apoptosis,improve neurological dysfunction probably by activating autophagy in neuron and play a role in brain protection.