The Protective Effects Of Hyperoxygen Liquid On Brain Ischemia Injury And Part Of The Mechanisms

Background: Ischemia-reperfusion injury in brain results in the functional disturbance in CNS which seriously decrease the quality of lives and even threaten the patients' life. The hyperoxygen liquid (HL), which carries high concentration oxygen and contains reactive oxygen(10-20 mg·L-1), created a new method to the therapy of cerebral ischemic disease. It is reported that HL has valid protective effects on the cardiac ischemic and spinal cord ischemic diseases. In this study, through the experiment in vivo as well as in vitro, we proved that HL could mitigate the cerebral ischemia and reperfusion injury. The works were also done in discovering part of the mechanisms of these effects.PART ONE: Objective: To investigate the protective effects of HL on the cerebral ischemia model. Method: 18 mature domestic rabbits were randomly divided into three groups (6 rabbits each), control group (Group C); HL therapy group (Group T) and HL preconditioning group (Group P). All animals were prepared in cerebral ischemia-reperfusion model by Smith's method (2.A 2-vessel occlusion model). In Group T the HL 20ml · kg-1 (which was replaced by balance salt in Group C) was given intravenously after reperfusion. In Group P HL 20ml ?kg" was daily infusedintravenously for 3 days before ischemia. The blood samples were taken from internal jugular at different time points (before ischemia, after 20min ischemia and after 45 min reperfusion). The amount of NO and MDA and the activity of SOD in plasma was detected at different time point. After the operation the animals woke up with no interference and were normal fed. All animals were killed after reperfusion 72h and hippocampus CA1 were resected for histopathological study. Result: The activity of SOD was decreased and the amount of MDA and NO in plasma was increased after ischemia-reperfusion. The degrees of these changes were modified in the group T and group P and had significant difference when they were compared with group C (P<0.05 or P<0.01). The histopathological study was showed that hippocampus CA1 injury were significant difference among three groups. The percent of injured cell was 93.14% in Group C, 27.37% in Group T and 45.99% in Group P. Conclusion: HL could mitigate the cerebral ischemia-reperfusion injury.PART TWO: Objective: To investigate the protective effects of HL on the oxygen and glucose deprivation (OGD) in cultured neuronal cell. Method: The neurons dissociated from the newborn mice brain had been cultured for 14 days. To make the ischemia-reperfusion model in vitro, the neurons were exposed to OGD 4h and then were placed in normal culture media. Group Control (Group C) was taken as blank group. In group TI: the HL which took 33.3 percent volume of the culture media was given to neurons after the oxygen-glucose (OG) regained. And the HL took 25 percent volume of the culture media in Group T2. The neuronal injury was detected by MTT assay in different time (before OG deprived, 4h after OGD,4h, 12h, 24h after OG regain) and by trypan blue stained after OG regain 24h. Furthermore, the activity expression of nNOS and iNOS were detected by immunohistochemical technique between Group C and Group T\ which were OG deprived 30min and OG regained 4h instead. Result: The activity of neurons (MTT assay) was decreased constantly in each group during the experiment. But it was higher in Group TI and Group T2 than in Group C at every time. The percentage of positive neurons stained by trypan blue was smaller in Group TI and Group T2 than in Group C. There was no significant difference between Group TI and Group T2. In view of the positive expression of nNOS and iNOS, there was significant difference between Group C and Group TI. Conclusion: HL can mitigate the damage of OGD neurons and the restrained effect on NOS may be a part of the mechanisms.Summary: The HL can effectively decrease the percent of the dead neurons in hippocampus CA1 after the cerebral ischemia-reperfusion. It also has the effect of increasing the percent of survived neurons after OGD in v...