高压氧对大脑中动脉阻塞模型大鼠脑组织中Mcl-1表达的影响及其脑组织损伤作用机制

Influence of hyperbaric oxygen in MCl-1 expression in brain tissue of rat MCAO models and mechanism of its brain tissue injury effect

目的:探讨高压氧(HBO)对大脑中动脉阻塞(MCAO)模型大鼠脑组织抗凋亡蛋白髓细胞白血病因子1(Mcl-1)表达的影响,阐述高压氧对受损脑组织的损伤作用机制。方法:随机选取20只健康雄性Wistar大鼠,分为假手术(Sham)组6只、模型(MCAO)组和HBO组各7只。采用线栓法制作MCAO模型。Sham组仅进行血管分离,MCAO组缺血90min进行再灌注,HBO组在MCAO组的基础上,于再灌注3h时,给予3.0绝对大气压(ATA)高压纯氧治疗1h;所有大鼠于再灌注24h后处死。取脑组织冠状切片,用1%红四氮唑(TTC)染色检测并计算梗死面积;取大脑皮层梗死边缘区组织提取RNA和蛋白质,采用RT-PCR法检测Mcl-1mRNA表达水平,Western blotting法检测Mcl-1蛋白表达水平。结果:与MCAO组比较,HBO组大鼠脑梗死面积比明显增加(P<0.01)。与Sham组比较,MCAO组大鼠脑组织中Mcl-1mRNA表达水平显著升高(P<0.01);与MCAO组比较,HBO组大鼠脑组织中Mcl-1mRNA表达水平显著升高(P<0.01)。与Sham组比较,HBO组和MCAO组大鼠脑组织中的Mcl-1蛋白表达水平显著降低(P<0.01);HBO组与MCAO组Mcl-1蛋白表达水平比较差异无统计学意义(P>0.05)。与MCAO组比较,HBO组Bax/Mcl-1水平明显升高(P<0.01)。结论:高压氧可能通过促进Mcl-1的降解,引起Bax/Mcl-1平衡失调,导致神经细胞凋亡而加剧组织损伤。

Objective To explore the effect of hyperbaric oxygen（HBO）on brain tissue of rats suffered transient middle cerebral artery occlusion（MCAO）and the Mcl-1expression in brain cortex,and to demonstrate its mechanism.Methods 20healthy male Wistar rats were chosen and separated randomly to sham group（n=6）,MCAO group（n=7）and HBO group（n=7）.The MCAO models were established by nylon strand method.In sham group,the blood vessels were dissected and the strand was not inserted to middle artery;the rats in MCAO group were reperfused after 90 min ischemia,and the rats in HBO group were given pure oxygen at 3.0atmospheres absolute（ATA）for 60min after 3hreperfusion.24hafter reperfusion,all the rats were killed.The infarct area of coronal brain section was calculated with 2,3,5-triphenyltetrazolium chloride（TTC）staining;the expressions of Mcl-1mRNA and protein in cortex of penumbra were detected by RT-PCR and Western blotting,respectively.Results Compared with MCAO group,the infarct area ratio of the rats in HBO group was increased obviously（P0.01）.Compared with sham group,the Mcl-1mRNA level in brain tissue of the rats in MCAO group was up-regulated notably（P0.01）.Compared with MCAO group,the Mcl-1mRNA level in brain tissue of the rats in HBO group was raised significantly（P0.01）.Compared with sham group,the Mcl-1protein contents in brain tissue of the rats in MCAO and HBO groups were decreased significantly（P0.01）;but there were no statistically significant differences（P0.05）.Compared with MCAO group,the Bax/Mcl-1levels in HBO group were increased significantly（P0.01）.Conclusion HBO may promote the damage of MCAO rats through increasing the degradation of Mcl-1.