A Study Of Apoptotic Status And Expression Of Bcl-2 Bax Gene In Brain Tissue After Severe Injury

The incidence of brain injury was increased year by year with the development of the economy and transportation. After injury the mortality rate and mutilation rate were also increased. It was conducive to clinical decision by measuring the abnormal expression of gene and protein to study the injury mechanism. Apoptosis, also called programmed cell death. It refered to the procedure that cells end their lives following certain programs in a physiological or pathological condition. Apoptosis was necessary in development of vital process and is very important in maintaining normal physiological function of organism. If apoptosis was abnormal, all kinds of disease may occurs. Bcl-2 (B cell lymphoma/leukemia 2) and Bax (Bcl-2 associated x) were the regulator genes in apoptosis and played a important role in the occurrence of apoptosis. Bcl-2 encoded a 26KD protein, which localized to outer mitochondrial membranes. Overexpression of Bcl-2 can blocked occurrence of apoptosis. Bax encoded a 21 KD protein. Bax protein could form-5-homodimer. On the contrary, overexpression of Bax could promote occurrence of apoptosis. In our study, 50 healthy male SD rats were experimented, half of them were injured in the brain. TUNEL (terminal-deoxynucleotidyl transferase mediated nick end labeling) and immunohistochemisty were used to detect apoptosis and Bcl-2> Bax expression in all the brain tissue.Materials and methods1.Animals: 50 healthy male SD rats (Body weight: 200g)were divided into two groups (injury group and non-injury group) in random.2.1njury: Both two groups were opened a bone window in lelt parietal bone ( diameter:4.5mm) . Rats of injury group were get severe brain injury by improved Feeney free dropping objective mode.3.Material: 5 rats were killed respectively in both two groups at 6ru 12h> 24h> 72h> 168h (7 days) after injury. Then make paraffin specimen section after took out of all the brain tissue completely.4.Detection: Apoptosis were detected by TUNEL and Bcl-2N Bax were detected by immunohistochemisty.5.Observation: The positive cells were counted under light microscope and then the labeling index (LI) were calculated.6.Statistics: The data were analyzed by statistical package (SPSS 10.0 for windows) . Main statistical method were t-test and correlation-test.-6-Results1.There were significant differences between the injury group and non-injury group(p<0.01 )with more TUNEL positive cells in the injured rats. In the injury group, LI of TUNEL positive cells changed with the time reaching a higher level at 72 hours after injury.2.Bax positive cells in the uninjured rats were less than those in the injured rats. There were significant differences between the injury group and non-injury group (p<0.01) . LI of Bax positive cells also changed with the time reaching a higher level at 72 hours after injury.3.There were more Bcl-2 positive cells in the injured rats, than that in the uninjured rats. Some differences existed between two groups (p<0.05) . LI of Bcl-2 positive cells reached a higher level at 24 hours after injury.4.Because the effect of Bcl-2 and Bax on occurrence of apoptosis were opposite and they both overexpressed in brain tissue after injury, we calculated the value of Bax/Bcl-2. In injured rats the value was larger than that in uninjured rats. There were significant differences between two groups (p<0.05) . And in injured rats this value got changes with the time. At 72 hours after injury, this value was biggest.5.We analyzed the relationship between LI of TUNEL positive cells and Bcl-2 > Bax positive cells with the time by using correlation-test. But there was no significant correlation between these data (p>0.05) .Conclusions1.Apoptosis is a pathological alteration in nerve cells after severe brain injury.2.Bcl-2> Bax gene participate in regulation of apoptosis after severe brain injury.3.Disequilibrium between the Bcl-2 and Bax maybe the reason of promoting apoptosis in nerve cells after severe brain injury.