VEGF/FLK-1 Signal And MMP-7 Gene Expression After Traumatic Brain Injury And Its Forensic Significance

Objective: To study the expression and distribution of VEGF / FLK-1 signal and MMP-7 gene in brain tissues outside the hippocampus and hippocampus after traumatic brain injury,and to explore their molecular mechanism of action after traumatic brain injury and the relationship between their expression changes and injury time,and provide relevant experimental basis for forensic and molecular pathology research of traumatic brain injury.Methods: Forty SD rats(both female and male,weighing 250 ± 10 g)were randomly divided into normal control group(Normal group,5)and traumatic brain injury group(TBI group,35),of which TBI group is divided into 7 subgroups: TBI 30 min group,TBI 6 h group,TBI 1 d group,TBI 3 d group,TBI 5 d group,TBI 7 d group,TBI 9 d group.According to the principle of Marmarou’s free-fall strike model,design a free fall striker by yourself and build a TBI model.By observing the behavioral changes of the model group rats and H-E staining of the brain tissue,it is judged whether the modeling is successful,the brain tissues of rat hippocampus and outside the hippocampus were taken separately,and the protein changes of expression of VEGF,FLK-1 and MMP-7 genes were detected by immunohistochemical staining technique,immunofluorescence staining technique and Western Blot technique.Results:(1)In the normal control group,the VEGF,FLK-1,MMP-7 genes in the hippocampus of the rat brain,cerebral cortex,and medulla are all expressed in small amounts.Compared with the normal control group,in the hippocampus of the model group: the expression of VEGF and FLK-1 in VEGF / FLK-1 signal continued to decrease within 6hours after injury,and the expression increased sharply after 6 hours,the expression began to decrease after reaching the peak at 3 days,and maintained at a level higher than the normal group;the expression of MMP-7 began to be up-regulated immediately after injury,the expression decreased sharply after reaching the peak at 3 days,and the expression decreased slowly after 5 days,and maintained at a level higher than the normal group.(2)In the cerebral cortex and medulla,the expression and distribution of VEGF,FLK-1,MMP-7 are wider in the medulla than in the cortex,compared with the normal control group,in the cerebral cortex and medulla of the model group: the expression of VEGF increased slightly within 30 min after injury,and began to decrease after 30 minutes,the expression was lower than that of thenormal group at 6 hours,the expression was up-regulated after 6 hours and began to decrease again at 3 days,after 5 days,the expression continued to increase and maintained at a high level;the expression of FLK-1 continued to decrease within 6 hours after injury,the expression increased after 6 hours,and slowly decreased after reaching the peak at 3 days,but remained at a level higher than that of the normal group;the expression of MMP-7 began to increase continuously after injury,and the expression decreased sharply after reaching the peak at 7 days,but it was still higher than that of the normal group.Conclusion: Genes of VEGF / FLK-1 signaling and MMP-7 are up-regulated after traumatic brain injury,which may repair brain injury through angiogenesis,neuron and glial regeneration.In traumatic brain injury,the expression of VEGF / FLK-1 signaling gene and MMP-7 gene is dynamic,which may be related to the occurrence and development of traumatic brain injury.The expression of the three genes VEGF / FLK-1 and MMP-7 in the hippocampus and the cerebral cortex and medulla outside the hippocampus is not completely consistent,there are differences,their expression trends in traumatic brain injury have a certain reference value in inferring the injury time of traumatic brain injury in forensic.