Experimental Study On Influences Of The Brain By Giving Pure Oxygen In Different Time Points After The Global Cerebral Ischemia Reperfusion In Rats

Objective: Making a global cerebral ischemia reperfusion model of rat to compare theinfluences on cerebral injury when giving pure oxygen at different reperfusion time pointsand to find a security time range to improve oxygen concentration after the global cerebralischemia reperfusion.Method:48healthy Sprague-Dawley male rats were randomly divided into6groupsof eight rats each: Control group (Sham, sucked in room air), Pure oxygen group (givenpure oxygen for1h immediately after reperfusion), Pure oxygen group1(0.5h later afterreperfusion to give pure oxygen for1h), Pure oxygen group2(1h later after reperfusionto give pure oxygen for1h), Pure oxygen group3(2h later after reperfusion to give pureoxygen for1h), Air group (sucked in room air all the time). Referring to thePulsinelli-method, we made the global cerebral ischemia reperfusion model of rats. Theduration of global cerebral ischemia was15minutes. Before reperfusion (0H) and inreperfusion (0.5H,1H,2H,4H), blood was collected from the right internal jugularvenous. After centrifuging, the serum was used to test the concentration of heterogeneousprostaglandin (8-iso-PGF2α) and protein S-100B.24hours after reperfusion, the brain wastook out from the head, then one half of brain was used to measure brain water content. Theother half was fixed with4%paraformaldehyde for24hours and then was made intoparaffin section for TUNEL staining to observe neuronal damage finally.Results: In Pure oxygen group and Pure oxygen group1, the levels of8-iso-PGF2α and protein S-100B in internal jugular venous after given pure oxygen, the neuronalapoptotic percentage and brain water content were higher than which in Air group, and thedifferences have statistical significance. In Pure oxygen group2, except for S-100B, theother indicators after given pure oxygen were statistically different when compared withAir group, and except for8-iso-PGF2α, there’re no difference between Pure oxygen group3. There is no statistical difference between Pure oxygen group3and Air group.Conclusion: Early in the process of global ischemia-reperfusion (in the first1hour),pure oxygen can aggravate cerebral injury by activating the oxidative stress. However, ifgiving later (2hours after reperfusion maybe) the influences may be much smaller.