缺血后处理对脑缺血再灌注大鼠TNF-α和IL-1β表达影响

EFFECTS OF ISCHEMIC POSTCONDITIONING ON TNF-α AND IL-1β EXPRESSION IN RATS AFTER CEREBRAL ISCHEMIA/REPERFUSION

目的探讨缺血后处理(IP)对局灶性脑缺血再灌注(I/R)大鼠肿瘤坏死因子-α(TNF-α)和白细胞介素-1β(IL-1β)表达的影响。方法将110只成年健康雄性SD大鼠随机分为假手术组(sham组)10只、I/R组和IP组各50只,后两组根据再灌注时间每组又分为6、12、24、48、72h等5个亚组。采用大脑中动脉线栓法建立局灶性脑I/R模型,后处理方法为大脑中动脉阻闭2h后,再灌注15s-缺血15s,反复3次。对各组进行神经行为学评分,TTC染色测定脑梗死体积,免疫组化法检测脑组织TNF-α和IL-1β蛋白表达,原位杂交法检测TNF-α和IL-1βmRNA的表达。结果 I/R组大鼠可见神经行为学的缺失及缺血侧大脑半球的梗死,与之相比,IP组大鼠脑梗死体积明显减小、神经行为学评分改善(t=2.683～5.657,P<0.05)。TNF-α、IL-1β蛋白及mRNA在sham组额顶叶有微弱表达,其在I/R组和IP组的表达于再灌注6h时开始升高,24h达高峰。与I/R组各相应亚组比较,IP组TNF-α和IL-1β蛋白及mRNA表达均明显降低(t=2.333～7.814,P<0.05)。结论 IP可显著下调TNF-α和IL-1β的表达,缩小I/R大鼠的脑梗死体积,提示IP可抑制I/R的炎性反应,从而发挥神经保护作用。

Objective To investigate the effects of ischemic postconditioning on expression of tumor necrosis factor-α（TNF-α） and interleukin-1β （IL-1β） in rat models of focal cerebral ischemia/reperfusion. Methods This study consisted of 110 adult healthy male Sprague-Dawley rats. They were randomized to sham-operation group （n= 10）, the rest 100 were evenly divid- ed into ischemia-reperfusion group （I/R group） and ischemia-postconditioning group （IP group）. The latter two groups were sub- divided into five subgroups according to different time points of I/R as 6-, 12-, 24-, 48- and 72-hour groups, with 10 of each group. A model of focal cerebral ischemia-reperfusion was created by intraluminal threading of middle cerebral artery occlusion （MCAO） and IP for 2 h, then reperfusion for 15 seconds, followed by ischemia for 15 seconds, which was repeated for three times. Each group was evaluated for neuroethology, TTC staining of the volume of the infarcion, immunohistochemical method was employed for the expressions of TNF-α and IL-1β protein, and in situ hybridization for TNF-a and IL-1β mRNA expressions. Results The neurobehavioral deficit and cerebral infarction were seen in the I/R and IP group, as compred between them, the vo- lume of infarction was smaller, and the neuroethology improved in IP group （t= 2. 683-5. 657, P〈0.05）. Slight expressions of TNF-α and IL-113 could be found in the frontoparietal lobe in the sham-operation group, but the expressions in I/R and IP group started to rise at six hours of reperfusion, reaching their peak at 24 hours. Compared with corresponding subgroups of I/R, the ex- pressions of TNF-α, IL-1β protein and mRNA in IP group declined significantly （t=2. 333-7. 814,P〈0.05）. Conclusion 1P down-regulated the expressions of TNF-α and IL-1β, reducing the volume of cerebral infarction, which indicates that IP can inhibit inflammation caused by ischemia-reperfusion and play a role in the neuroprotective effect.