亚低温在大鼠脑缺血再灌注中对氨基酸和自由基系统动态平衡的影响

The effect of mild hypothermia on dynamic balance of amino acids and free radicals during cerebral ischemia and reperfusion in rats

目的 研究亚低温状态下 ,缺血 /再灌注损伤时大鼠脑皮质内 4种氨基酸含量和自由基含量的动态变化 ,以探讨亚低温对脑缺血再灌注损伤时的保护机制。方法 采用大脑中动脉线栓模型 ,将Wistar大鼠随机分为假手术组、常温组和亚低温组 ,其中后 2组又根据其观察时间点分为 4个亚组 (分别为缺血 3h组 ,缺血 3h后再灌注 1h组、再灌 2h组及再灌 3h组 )。观察各组大鼠缺血脑皮质内的氨基酸及自由基系统物质含量的动态变化。结果 与假手术组比较 ,常温组和亚低温组缺血脑皮质内SOD与GSH PX的含量在各时间观察点均明显降低 (P <0 .0 5 ) ,而MDA含量则明显升高 (P <0 .0 1) ;常温组和亚低温组的Asp含量、常温组的Glu含量、亚低温组的Gly和GABA含量在各时间观察点与假手术组比较 ,也均明显升高 (P <0 .0 5 )。与常温组比较 ,亚低温组大鼠脑缺血皮质内SOD和GSH PX的含量在各时间观察点均明显增加 (P <0 .0 5 ) ,而MDA含量则明显减少 (P <0 .0 1) ,亚低温组大鼠缺血脑皮质内Asp和Glu的含量在各时间观察点均明显下降 (P均 <0 .0 5 ) ,GABA含量在各时间观察点均明显升高 (P均 <0 .0 5 ) ,Gly含量在缺血 3h和缺血3h再灌注 1h时有显著升高 (P <0 .0 5 )。结论 亚低温可影响氨基酸和自由基系统的动态平衡 。

Objective To evaluate the effect of mild hypothermia on amino acids and free radicals in rats during cerebral ischemia and reperfusion. Methods Sixty-three Wistar rats were used in this experiment. Zea-Longa' s method was employed to establish the middle cerebral artery occlusion model in 56 rats, which were then randomized into a normal temperature group (n=28) and a mild hypothermia group (n=28). The other 7 rats underwent sham operation and served as control. The rats in the former two groups were observed at 4 time points (3 hours of cerebral ischemia, 1, 2 and 3 hours reperfusion after 3 hours of ischemia) with regard to the dynamic changes of various amino acids and free radicals in the cortex of the rats. Results Compared with the sham operation group, the concentration of SOD and GSH-PX in the ischemic cortex of normal temperature group and mild hypothermia group decreased significantly (P<0.05), while that of MDA increased at all observation time points(P<0.01), the concentration of Asp in normal temperature and mild hypothermia temperature groups, that of Glu in normal group, that of Gly and GABA in mild hypothermia group all increased markedly at the four observation time points(P<0.05). Compared with the normal temperature group, the concentration of SOD and GSH-PX in ischemic cortex increased (P<0.05 or P<0.01)in mild hypothermia group, while that of MDA decreased (P<0.01), the concentration of Asp and Glu in ischemic cortex were much lower at all observation time points(P<0.05), whereas that of GABA was much higher at all observation time points(P<0.05), that of Gly increased at time points 3 hours of ischemia and 1 hours of reperfusion after 3 hours of ischemia(P<0.05). Conclusion Mild hypothermia could influence the balance of amino acids and free radicals, which might be one of the mechanisms of mild hypothermia ameliorating ischemia-reperfusion cerebral lesion.