| Background Diffuse axonal injury(DAI)is an injury characterized by swelling and Diffuse distribution of axonal fractures in the brain.It is one of the most common and important pathological features of TBI.When the head is subjected to mechanical external forces(such as traffic accidents or falls),rapid horizontal pull or rotary shear force applied to brain tissue can cause complete fracture or partial damage of axons,and then trigger molecular pathways leading to secondary axonal fracture or degeneration.The histological pattern of DAI is contractile ball formation and axonal swelling,thickening,and distortion.The occurrence of these lesions is related to microtubule dysfunction and fracture,which leads to microtubule wavy changes and axonal transport disorders,and then accumulation of axonal transport materials such as pat-app.Small pathologic changes in the axon of DAI are difficult to differentiate with conventional non-invasive imaging techniques such as conventional CT or MRI,and this insidious lesion causes great diagnostic difficulties.Therefore,it is a hot topic to further study the changes and regularity of biomarkers after DAI,and to find reliable intracranial or extracranial biomarkers for diagnosis,understanding the development of disease,or inferencing long-term prognosis.Calsenilin(CSEN)is a member of neuronal calcium sensor(NCS)protein family.It was first identified that the protein binds 40 amino acids at the c-terminal of presenilin2(PS2)and regulates the level of proteolytic products of PS2.CSEN plays A role in regulating synaptic plasticity and learning and memory,and can regulate cell apoptosis and amyloidamyloid(A)deposition.Therefore,as a potential biomarker of TBI,CSEN is of great research value in whether it also has certain diagnostic significance in posterior axonal injury of DAI and whether it can be used to infer long-term prognosis.Objectives 1.To study the expression of CSEN in posterior axon of DAI in rats.2.To investigate the function of CSEN in secondary injury after DAI in rats.3.The application value of CSEN as molecular marker was discussed.Methods 1.Adult male Sprague Dawley(SD)rats were divided into sham operation group and injury group,and DAI model of rats was established according to Marmarou free-fall hitting method to model the injury group.2.The modified neurological severity scores(m NSS)were used to evaluate the injury degree of rats,and the individuals with minor injuries were excluded.3.Rat brain tissues were collected at 0h,6h,1d,2d,3d and 7d after DAI,and the axonal damage was evaluated by HE staining to verify the feasibility of the model.Western blot was used to detect the changes of CSEN expression in posterior axons(brainstem and corpus callosum)of DAI in rats,to analyze the relationship between the changes of CSEN expression level in axons and DAI injury degree,and to explore its function in post-dai secondary injury.4.Cerebrospinal fluid and blood of rats were collected 6h,1d,3d and 7d after DAI,and the concentration level of CSEN was detected by ELISA to analyze the correlation and clinical significance between the CSEN concentration level in cerebrospinal fluid and serum after injury and the expression level in brain.Results 1.The m NSS score of the rats after DAI injury showed that most of the rats had moderate to severe neurological function damage after the model construction.Compared with the sham operation group,the score of the rats in the injury group showed a significant increase immediately after the injury,a small decrease in the score at 6h after the injury,and a further increase on 1d after the injury,reaching the peak.After 1d of injury,the m NSS score gradually decreased,and the score on day 7 after injury decreased to the level of mild brain injury,but did not return to the normal level.2.HE staining of the brain of the DAI group showed obvious cerebral edema,scattered foci and patchy subarachnoid hemorrhage,decreased volume of some cortical neurons,deep cytoplasmic staining,nuclear shrinkage or dissolution,and ischemic and hypoxic changes.There were contusion foci in the brainstem and corpus callosum,and only slight edema was observed within 6h after the injury,and no obvious axonal lesions were observed.After injury,obvious axonal swelling,thickening,distortion and ball formation were observed in the first ~2d.The lesion was in remission from 3 to 7 days after injury.3.Western blotting results showed that there was no significant change in the expression of 0h after CSEN injury in the brain stem of the DAI group.One day after the injury,it showed obvious enhancement and continued to the 3rd day.On the 7th day after injury,the expression level was still increased.There was no significant change in the expression of CSEN in the corpus callosum of rats within 6h after CSEN injury.One day after the injury,it showed obvious enhancement and continued to 2d.After the injury,there was a drop in 3d.It increased again 7 days after injury 4.ELISA results showed that the concentration of CSF in the DAI injury group significantly increased 6h after CSEN injury and continued to increase to 1d.The concentration of CSF suddenly decreased 3 days after injury and significantly increased again on the 7th day after injury.The serum CSEN concentration began to increase at 6h after CSEN injury,and showed a continuously increasing state,and it still maintained an increasing trend at 7d after injury.Conclusions 1.The high expression of CSEN in axons after injury suggests that it is involved in the repair process of secondary axonal injury,but this repair process may lead to accumulation of A,which may promote long-term chronic neurodegenerative diseases after DAI.2.The expression of CSEN after DAI can be used as a biomarker to evaluate the repair ability after injury.Combined with other biological indicators that can reflect the intensity of injury after brain injury,it can reasonably infer the development trend of the disease.3.CSEN in cerebrospinal fluid and serum after DAI can better reflect the changes in its expression in axons and can be used to evaluate the situation of brain injury. 4.CSEN is an extracerebral biomarker for chronic and degenerative diseases after DAI. |
PDF Full Text Request