Effect Of Semaphorin 3A On Secondary BBB Damage After TBI

Objective: the traumatic brain injury(TBI)is a kind of disease extremely high mortality and morbidity in the area of neurosurgery,the secondary brain damage after TBI,such as intracranial inflammation,blood coagulation dysfunction has a promoting effect in patient's neurological dysfunction and death,significant increase the adverse consequences caused by primary damage.Blood-brain barrier damage after TBI and the occurrence of cerebral edema occupies a large proportion in traumatic brain injury lethal factor.The pathological damage such as intracranial inflammation,intracranial pressure caused by this greatly increase nerve dysfunction caused by TBI.Semaphorin 3A(SEMA 3A)is the member of the SEMAs family which first be researched to be nerve guide factor,because the proteins play an important role in many diseases and has been widely concerned.SEMA 3A is not only negative regulatory proteins of the growth of axons,also play an important role in inhibiting angiogenesis,cell migration,apoptosis,tumor growth,regulate immune response and so on in a variety of pathophysiological process.Some studies have proved that SEMA 3A can lead to a significant increase in vascular permeability mediated by VEGF or not.This experiment product traumatic brain injury model with CCI,explore the change rule of SEMA 3A amount and the interaction site in brain tissue in injury cycle of TBI.through the lateral ventricle injection SEMA 3A,observe its influence of opening the blood-brain barrier and the brain water content after TBI.Detect whether SEMA 3A is the influence factors of secondary blood-brain barrier damage and occurrence of brain edema after TBI.Methods: 1,adult male C57/BL6 mouses were randomly divided into sham group,first day after TBI group,third day after TBI group,seventh day after TBI group and fourteenth day after TBI group,each group has 6 mouses,TBI group product traumatic brain injury model with CCI,sham group is only grinded bone window without CCI.Using Western blot method to detect SEMA 3A content of each group of experimental animals in brain tissue.Test SEMA 3A content and distribution with immunofluorescence.2,18 adult male C57/BL6 mouses were randomly divided into TBI + PBS group,TBI+SEMA 3A group and TBI + SEMA 3 a + antibody group,each group has six mouses.TBI + PBS group injects PBS in lateral ventricle immediately after producting TBI model wth CCI.TBI + SEMA 3A group injects SEMA 3A protein in lateral ventricle immediately after producting TBI model wth CCI.TBI + SEMA 3A + antibody group injects SEMA 3A protein in lateral ventricle immediately after producting TBI model wth CCI,after 24 h,injects SEMA 3A monoclonal antibody in lateral ventricle.Kill mouses in the edema peak time,third day after TBI,applicate Brain water content measurement to detect water content in brain tissue,applicate EB dye extravasation assay to detect the blood-brain barrier(BBB)damage.Results: Western blot test shows that SEMA 3A content after TBI is higher than sham group,and SEMA 3A content trend in TBI injury circle is first increased and reduce,reach the peak value at the third day after TBI,each time point difference has statistical significance(P < 0.05).Immunofluorescence tests revealed SEMA 3A content trend and Western blot test results are consistent,and concentrated distribution around the trauma area.Brain water content measurement shows water content in brain tissue of TBI + SEMA 3A group is significantly higher than TBI + PBS group,and water content in brain tissue of TBI + SEMA 3A + antibody group is significantly lower than TBI + SEMA 3 group.The difference has statistically significance(P < 0.05).EB dye extravasation assay shows that Evans Blue leakage in brain tissue of TBI + SEMA 3A group is significantly higher than TBI + PBS group,while Evans Blue leakage in brain tissue of TBI + SEMA 3A+ antibody group is significantly lower than TBI + SEMA 3A group.The difference has statistically significance(P < 0.05).Conclusion: SEMA 3A content in brain tissue is significantly increased after TBI,and SEMA 3A can increase the leakage of the blood-brain barrier in mouse after TBI,promote the occurrence of cerebral edema.