Sequential Changes Of Tau,Ng And Nfl After Craniocerebral Injury In Rats Chemical Research

Objective:To establish a rat model of traumatic brain injury(TBI)and detect the expression of Tau,Neurogranin(Ng),and Neurofilament light chain protein(Nfl)in the hippocampus and serum,and to observe the changes in their expression over time after TBI,in order to enrich ideas for inferring the time of brain injury in the field of forensic medicine,And provide some theoretical reference for the study of brain injury mechanism.Methods:Ninety-six healthy male SD rats,weighing 200-220 g,aged 8 weeks,were randomly divided into 8 groups:normal control group(ZC group)and experimental group(6h 12h,1 d,3 d,5 d,7 d,14 d after TBI),with 12 rats in each group.The experimental group used the Marmarou method[1]to construct a diffuse brain injury model using a craniocerebral percussion device,and used the Longa[2]scoring method to measure the neurological damage in rats after brain injury.HE staining technique was used to study the pathological changes of brain tissue in rats during different periods of TBI.Immunohistochemical staining were used to detect the expression of Tau,Ng,and Nfl proteins in the hippocampus of rats in each group;The expression levels of Tau,Ng,and Nfl in the serum of rats in each group were measured by ELISA;The expression of Tau,Ng,and Nfl mRNA in the hippocampus of rats in each group was detected by qRT-PCR.In this experiment,the above methods were used to further analyze and explore the temporal changes of Tau,Ng,and Nfl in rats after TBI.result:1.Detection of behavioral results:After craniocerebral injury,rats in the expermental group showed significant respiratory rhythm disorders,unilateral hemiplegia,no response to acupuncture,inability to walk in a straight line,turning or tipping to one side while walking,and other symptoms.2.HE staining detection:Compared with the control group of rats,local subarachnoid hemorrhage appeared in the brain,cerebellum,and brainstem of the experimental group,with a small amount of inflammatory cells and fibrin exudation in the subarachnoid space,partial brain tissue accompanied by focal superficial brain contusion,and hemorrhage was also seen in the lateral ventricle and intracerebral venous plexus,with a small amount of inflammatory cell infiltration.As TBI time changes,neuronal degeneration occurs in the hippocampal sulcus and gyrus,with varying degrees of neuronal necrosis,structural disorder of pyramidal cells,loose arrangement,and a significant decrease in the number of neuronal cells.The perivascular space also widens,and protein edema,glial cell proliferation,neural phagocytosis,and satellite phenomena can be observed.The above indicates that the brain tissue of rats has the characteristics of TBI,and the neuronal degeneration in the hippocampus gyrus begins to be obvious 12 hours after TBI,especially at 1 day,the performance is more pro min ent.During this period,the nuclei undergo pyknosis and deep stainng,the eosinophilicity of the cytoplasm increases,and even membrane rupture and cell disintegration occur.The perivascular space widens significantly.The degree of neuronal necrosis and edema will be significantly reduced 3 days after TBI,and gradually recover after 7 days.Immunohistochemical staining:Tau,Ng,and Nfl proteins significantly increased 6 hours after TBI,with Tau expression reaching its maximum within 5 days after TBI;The expression amount of Ng reached the highest value on the 14th day;The expression of Nfl reached the highest value at 6 h;Compared with the normal control group,the differences were statistically significant(P<0.05).4.Elisa test:After 6 h of TBI,the concentrations of the three in serum were higher than those in the normal group,with Nfl reaching the highest peak;Ng decreased after reaching a small peak in 3 days and reached a peak in 7 days;Tau reached its peak in 5 d;Compared with the normal control group,the differences were statistically significant(P<0.05).5.qRT-PCR detection:Tau mRNA increased 6 hours after TBI,peaked at 3 days,and then began to decline;Ng mRNA showed an upward trend at 6 h after TBI,reached its peak at 7 d,and then gradually decreased;The expression of Nfl mRNA increased after TBI,with the highest expression at 6 h;Compared with the normal control group,the differences were statistically significant(P<0.05).Conclusion:1.The expression changes of Tau,Ng and Nfl in brain tissue hippocampus and serum in different time periods after TBI have a certain time sequence change rule,which can provide a certain theoretical basis for enriching forensic brain injury time inference.2.Detection of Tau,Ng and Nfl expression in brain hippocampus and serum may provide some reference value for forensic science to infer the early injury time of TBI,but the specific quantitative results need further study.