Observation Of Early Changes Of α-syn In Diffuse Brain Injury In Rat

Background and Objective Diffuse brain injury (DBI) is a common and serious brain injury with high morbidity and mortality. There are lack of visible and characteristic pathological changes in the earlier stage of DBI. The axonal retraction ball, as characteristic pathological changes in DBI, can be formed only at 12h after injury. Therefore, the early diagnosis has been the focus of the study today. To date, there are not yet effective methods or indicators for the early diagnosis of DBI. Meanwhile, dating of brain wound has also been a key issue in forensic science. In this study, we expected to provide a basis for the early diagnosis of DBI and dating of brain wound by copying the model of DBI in rats and observing the expression ofα-syn.Methods 60 SD rats were randomly divided into the DBI group and the control group. The DBI in rats were produced based on Marmarou's method.α-syn were detected in the 10 DBI groups at 30 min, 1h, 3h, 6h, 12h, 24h, 2d, 3d, 4d, 7d post-injury respectively and 1 sham-operated group and 1 normal control group by immunohistochemical staining in combination with imaging analysis. The data were analyzed by SPSS 11. 5 for Windows.Results1. The model of DBI were successfully replicated in the study.2. The number ofα-syn positive cells in DBI rat brain cortex, hippocampus, brainstem showed two peaks-like trend, such as increasing significantly followed by a decrease, and then a further increase. The number ofα-syn positive cells in the brain cortex was detected increasing at 1h, and increased significantly at 3h, and it reached apex at 6h after DBI, then it decreased gradually, achieved the lowest point at 48h, and the second peak appeard at 96h, and then recovered gradually after 7d. The number ofα-syn positive cells in the hippocampus have the same trend with the brain cortex on the whole, but the second peak appeared at 72h after DBI. The number ofα-syn positive cells in the brainstem was detected increasing at 3h, and it reached apex at 6h after DBI, then it decreased gradually, achieved the lowest point at 48h, and the second peak appeard at 72 h, and then recovered gradually after 7d.3. The the average optical density ofα-syn in DBI rat brain cortex, hippocampus, brainstem also showed two peaks-like trend. The average optical density ofα-syn in the brain cortex was detected increasing at 3h, and it reached apex at 6h after DBI, then it decreased gradually, achieved the lowest point at 48h, and the second peak appeard at 96h, and then recovered gradually after 7d. The average optical density ofα-syn in the hippocampus was detected increasing at 1h, and increased significantly in 3h, and it reached apex at 6h after DBI, and then it decreased gradually, achieved the lowest point at 48h, and the second peak appeard at 72h, and then it recovered gradually after 7d. The average optical density ofα-syn in the brainstem have the same trend with the number ofα-syn positive cells in the brainstem.Conclusions The number ofα-syn positive cells and the average optical density ofα-syn showed two peaks-like trend at different time in DBI rats, and the early changes ofα-syn was regular, especially within 6h after DBI. Detecting the early changes ofα-syn by immunohistochemistry can be used as the reference index in early diagnosis of DBI. Meanwhile, there is also a certain value for dating of brain wound.