异氟醚预处理对大鼠局灶性脑缺血再灌注时TLR4和MyD88表达的影响

Effects of isoflurane preconditioning on expression of TLR4 and MyD88 during focal cerebral ischemiareperfusion in rats

目的 评价异氟醚预处理对大鼠局灶性脑缺血再灌注时Toll样受体4（TLR4）和髓样分化因子88（MyD88）表达的影响.方法 雄性成年SD大鼠54只,体重250～300 g,随机分为3组（n=18）：假手术组（S组）仅分离血管,不留置线栓;脑缺血再灌注组（IR组）采用线栓法制备大鼠局灶性脑缺血再灌注模型,缺血2 h,再灌注24 h;异氟醚预处理（IP组）吸入2%异氟醚,1h/d,连续5 d,处理结束后24 h时制备大鼠局灶性脑缺血再灌注模型.再灌注24 h时进行神经功能缺陷评分,然后每组处死3只大鼠,测定脑梗死体积.分别于再灌注24、48和72 h时,处死5只大鼠,取右侧大脑缺血部位额叶皮质,采用Western blot法测定TLR4、MyD88和NF-κB的表达水平.结果 与S组比较,IR组和IP组神经功能缺陷评分升高,脑梗死体积增大,IR组TLR4、MyD88和NF-κB的表达均上调,IP组MyD88和NF-κB的表达上调（P＜0.05）;与IR组比较,IP组神经功能缺陷评分降低,脑梗死体积减小,TLR4、MyD88和NF-κB的表达均下调（P＜0.05）.结论 异氟烷预处理可通过抑制脑组织TLR4和MyD88的表达,减轻炎性反应,从而减轻大鼠局灶性脑缺血再灌注损伤.

Objectiye To investgate the effects of isoflurane preconditioning on expression of Toll-like receptor 4 （TLR4） and myeloid differentiation factor 88 （MyD88） during focal cerebral ischemia-reperfusion （IR） in rats. Methods Thirty male SD rats weighing 250-300 g were randomly divided into 3 groups （ n = 10 each）：sham operation group （group S）;focal cerebral IR group and isoflurane preconditioning group （group IP）. The animals were anesthetized with intraperitoneal pentobarbital 40 mg/kg. In group IR and IP a nylon thread with rounded tip was inserted into right internal jugular vein and threaded cranially until resistance was met. Mid-cerebral artery was occluded （MCAO） for 2 h followed by 24 h reperfusion. In group IP the animals inhaled 2% isoflurane98 % O2 for 1 h once a day for 5 consecutive days at 24 h before MCAO. Neurologic function was assessed and scored and cerebral infarct volume was measured at 24 h of reperfusion. The animals were sacrificed at 24, 48 and 72 h of reperfusion respectively. The right ischemic frontal lobes were removed for determination of TLR4, MyD88and NF-κB expression by Western blot analysis. Results MCAO significantly worsened neurologic function. The neurologic function deficit scores were significantly increased and the TLR4, MyD88 and NF-κB expression were significantly up-regulated in group IR as compared with group S （P 〈 0.05）. Isoflurane preconditioning significantly decreased cerebral infarct volumes and neurologic function deficit scores and down-regulated the expression of TLR4, MyD88 and NF-κB in group IP as compared with group IR （ P 〈 0.05）. Conclusion Isoflurane preconditioning can reduce inflammatory response and focal cerebral IR injury by down-regulating the expression of TLR4and Myd88.