| Objective: Traumatic brain injury (TBI) is a kind of harmful disease. The studies to its pathophysiologic process announce that many factors which cause " secondary damage " have take part in it and will decide the prognosis. Researches of the pathogenesis elucidate many different ingredients including the excess production of ROS, the excitotoxicity of aminophenol, calcium's overloading and the toxic byproducts of the metabolism deregulation. In recent years, the relatives between apoptosis and "secondary damage" have been emphasized. Apoptosis is a kind of cell death and characterized by cell suicide. Under some conditions, apoptosis and necrosis can change into each other. Apoptosis, commonly, can be classified into two avenues: the extrinsic approach and theintrinsic approach. For TBI, the intrinsic approach is primary. The key step of the intrinsic approach is the changes of mitochondrial membrane permeability and the release of the substances located in the intermembrane of the mitochondria. Among these substances, Cytochrome C ( CytC ) is released and results in the forming of appoptotic complex, then activing pro-Caspase3 and causing apoptosis . Release of CytC is controlled by many factors among which the members of Bcl-2 family may be very important. Bcl-2 and Bax , as anti-apoptotic and pro-apoptotic protein respectively, affect the mitochondrial membrane permeability closely. Hyperbaric oxygen (HBO) treatment as a traditional measure, though there are some suspicious opinions about it, is proved useful by a lot of clinical trials. Researches of HBO announce that it can reduce the production of ROS, regulate brain metabolism, decrease the expression of COX-2 and decline the expression of caspase and apoptosis. So we have the hypotheses that:(1) the protective effects of HBO lie in protecting the mitochondrial membrane and reducing the release of CytC. (2) The control of CytC releasing is compounded with the regulation of Bcl-2 and Bax by HBO.Materials and methods: 60 adult and health male SD rats, which weights' range from 220g to 280g, are classified into two groups: the experimental group and the control group. Then we duplicate the modelof TBI in the way of Freeney's method. Then the experimental group receives the HBO treatment (0.25Mpa, 1hour) in 30 minutes after TBI and the control group receives no special treatments. These two groups then are decollated in 3hr, 6hr, 12hr, 24hr and 72hr after TBI (every 6 rats in every time). Then the brain tissues around the focus of contusion are separated and made into frozen sections, some tissues being made into special sections in order to be observed by electromicroscope. The frozen sections are detected by anti-CytC antibody, Bcl-2 antibody and Bax antibody in the methods of immunohistochemistry. The statistics is analysised by t-test.Result: Immunohistochemic results indicate that after HBO treatment, the expression of CytC and Bax in the neuronal cytoplasm decline significantly ( P<0.05) except in the time of 72 hours after TBI; the Bcl-2 expression is up-regulated significantly(p<0.05) after TBI. The images of electromicroscope indicate that before 24hr after TBI, mitochondria of control groups become more swoln even fracted and the matrixes become vaguer than those of being treated with HBO. But when after 72hr of TBI, these two groups have no significant difference.Conclusion: (1) HBO treatment can reduce the release of CytC from mitochondria within 24hr after TBI. (2) HBO treatment can up-regulate the expression of Bcl-2 within 72 hr and decline the forming of dimericBax within 24 hr after TBI. (3) HBO treatment can alleviate themitochondrial edema with in 24 hr after TBI. (4) HBO treatment, whenas a single method, cannot protect mitochondria and arrest the release ofproteins located in intermembrane space completely. As a part ofcompound treatments, HBO will benefit other therapeutics. |
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