Research Of Effects Of Seawater Immersion On Rabbit's Open Brain Injury

[Objectives]To explore effects of seawater immersion on open brain injury, and investigate germs which possibly contaminate injuried open brain surface in oceanic environment.[Materials and Methods]Rabbits were subjected to stereostatic impact brain injury of moderate to severe severity. According to applied post-injury seawater immersion or not, animals were randomlized allocation into experimental group (seawater immersion group) and control group (simply injury group). Pathological changes of traumatic brain edema was observed by hematoxylin and eosin method at designed time points (Oh, 3h, 8h, 24h) after TBI. Bcl-2 and Bax protein expression was detected by immunohistochemistry, and analysed by computer assisted microscope image analysis system. Additionally, swabs which were taken of the surface of the open wound were collected for bacterial identification .[Results]1. Open brain injury animal model, which was established successfully by steoreostatic impact, and the latter local immersed wound of seawater met the demand of experiment.2. Pathological changes by HE method indicated that post-injury traumatic brain edema was aggravated as a result of seawater immersion. In the experiment, the deteriorism of traumatic brain edema in immersion group was still observed after 8 hours while in the control group the level of traumatic brain edema came to its summit.3. By immunohistochemistry method, the positive expression of Bcl-2 and Bax proteins was observed in some neural cells around brain contusion. Those cells expressing Bcl-2 didn't demonstrate morphological features of apoptosis,and their nucleuses wereintegrity. A few neural cells expressing Bax showed shrinkage and pyknosis. They had some morphological features of apoptosis.4. Immunohistochemistry analysed by software of ImagePro Plus showed that the ratio of Bcl-2 to Bax in seawater immersion group decreased contrasted with the control, which suggested seawater immersion increasing possibility of the apoptosis of neural cell.5. Bacteriological analysis indicated that, in the circumstance of such experiment, there existed the possibility of various germs contamination on the open brain surface. Actually, not only common pathogenic bacteriums, but some uncommer non-pathogenic ones were isolated. It must be pointed out that in some immersion case, oceanic microorganisms such as pathogenic vibrio were also detected.[Conclusion]Seawater immersion not only aggravated the TBE induced by steoreostatic impact, but also decreased the ratio of bcl-2/bax (bcl-2 declined, bax rose) of neural cells around brain contusion. Down regulation of the ratio (Bcl-2/Bax) would increase the possibility of injuried neural cells' apoptosis, which might lead to delayed neuron death. The result of bacteriological analysis showed that the more emphasis, in the identifying the pathogenic germ in clinic work, should be placed upon the reasonable, effective bacterial culture and detecting method.