| Early days ,It was authenticated in our lab that oxidative stress following traumatic brain injury could induce nerve cell apoptosis .But this signal transduction pathway is not clear .To find the key point of this pathway for new method of treatment , Our study was continued to research this signal transduction pathway.Objective: To investigate the expression of proteins associated with apoptosis in rats cerebral cortex and the changes of neural praxiology with the treatment of antioxidant Edaravone , To testify the signal transduction pathway of oxidative stress inducing nerve cell apoptosis and the possible protective mechanism of Edaravone on brain following traumatic brain injury in order to offer theoretic evidences for clinical theraphy and new prospects of theraphy.Methods: 180 male adult Sprague-Dawley rats weighting 300-350g were randomly divided into brain trauma, Edaravone treatment and control groups.Each group was divided into 6 subgroups according to time phase after traumatic brain injury ,that was 1h,3h,6h,24h,48h,72h. Treatment group was injected with Edaravone into vena caudalis with a dose of 10mg/kg/d,the other two groups were injected with the same volume of 0.9% normal sodium.Moderate closed brain injury according to Marmarou was improved, then the rats were killed at each time point.The histopathological damage in the cortex of the rats following traumatic brain injury were observed with HE staining. The change of expressions of Cytc, Bcl-2 and Bax in cortex of rats at defferent time points with the mothed of immunohistochemry, MDA with the mothed of TAB , and neural cells apoptosis with the mothed of TUNEL ;and change of neuropraxiology with the treatment of Edaravone after traumatic brain injury; The immunologic reaction of positive cells were analyzed with average optic density values detected by Motic Med 6.0 digital medical image analysis system; All the data were processed with SPSS 11.5 for windows.Results: Following injury ,decerebration and respiration suppression occered transiently. Hemmorrhage or yellow-shain could be seen in subarachoid of many rats .Scattered brain contusion could be noticed in the parietal lobe region and scattered degenerated and neroticed neuron 6h following injury ,which peaked at 24h with HE stain . The results as above were consistent with the manifestation described by Marmarou.Compared with control group the value of free radical intermediate product MDA increased at 6h after trauma, obviously at 24h and peaked at 48h(p<0.01).which was lower in each treatment group than trauma group especially at 24h,48h and 72h(p<0.01).Compared with control group,the immunity reaction of Cytc positive cell increased at 6h in trauma group and peaked at 24h, difference was significant at 3h,6h,24h,48h and 72h(p<0.01) . To compare with trauma group it could be decreased obviously at 24h,48h and 72h(p<0.01).The expression of Bcl-2 was hyperexcitability after traumatic brain injury , peaked at 3h, afterwards it could be decreased gradually.but the expression of Bax increased gradually after trauma ,and peaked at 48h.thus ,Bax/ Bcl-2 peaked at 48h.Edaravone could downregulate their ratio ,compared with trauma group ,deference was significant at 24h,48h and 72h(p<0.01).TUNEL positive cells increased gradually fallowing trauma ,before 24h cell death was mainly TUNELâ… -type,after 24h cell death was mainly TUNELâ…¡- type and peaked at 48h,compared with trauma group Edaravone can decrease obviously the quantity of apoptosis cell in rats cerebral cortex and difference was significant at 24h,48h and 72h(p<0.01).The value of MDA was related to the immunoreaction of Cytc from 1h to 24h(r=0.997,p<0.01); The value of MDA was related to the quantity of TUNEL positive cells from 1h to 48h (r=0.921,p<0.01); The ratio of Bax and Bcl-2 was related to the immunoreaction of Cytc from 1h to 24h (r=0.996,p<0.01),but the peak of the immunoreaction of Cytc(24h) was earlier than that of the ratio of Bax and Bcl-2(48h); The ratio of Bax and Bcl-2 was related to the quantity of TUNEL positive cells from 1h to 72h ( r=0.925,p<0.01)Analysis of neural praxiology:Edaravone could improve the defective degree of neurophysiological functions at 72h following traumatic brain injury(p<0.01).Conclusions: 1.There were two kinds of cell death for nerve cell in cortex after TBI:necrosis and apoptosis ,but the later was the main form of most of the nerve cell death.2. Oxygen free radical - mitochondria - Cytc was one of the signal transduction pathway of nerve cell apoptosis following traumatic brain injury. Traumatic brain injury made a great quantity of oxygen free radical,inducing mitochondrial permeability transition pore (PTP) open, Cytc released ,and Cytc was regulated by Bax and Bcl-2 in downstream led to the apoptosis of cortical neuron.3.Of the three factors lead to Cytc released- oxygen free radical, Bax and Bcl-2, oxygen free radical was possible the main factor , the ratio of Bax and Bcl-2 was important in regulation of Cytc release and in modulation of apoptosis gene expression after Cytc release.4. Edaravone showed therapeutic effect on traumatic brain injury ,and one of the mechanisms of antiapoptotic effects is by decreasing the generation of free radical, inhibiting the opening of PTP ,reducing the releasing of Cytc ,upgraduating the expression of Bcl-2 and decreasing the expression of Bax to decrease nerve cell necrosis and apoptosis. simultaneous , side effect of Edaravone for traumatic brain injury was not found.Thus we suggest applicate Edaravone in patient.
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