利多卡因对局灶性脑缺血再灌注大鼠HSP70 mRNA及其蛋白表达的影响

Effects of Lidocaine on expressions of HSP70 mRNA and HSP70 protein in cerebral cortex during transient focal cerebral ischemia-reperfusion in rats

目的:观察利多卡因对局灶性脑缺血再灌注大鼠脑组织热休克蛋白质(HSP70)mRNA及其蛋白表达的影响,并探讨其脑保护的机制.方法:60只雄性Wistar大鼠,采用大脑中动脉线栓法建立局灶性脑缺血再灌注大鼠模型,并随机将大鼠分为假手术组(Sham)、缺血再灌注组(I/R)和利多卡因组(缺血前10 min静脉注射利多卡因10 mg·kg-1).大鼠局灶性脑缺血2 h,然后进行再灌注.在再灌注3、6、24及72 h断头取脑组织,采用原位杂交法和免疫组织化学法检测其HSP70 mRNA和蛋白的表达.在再灌注24 h做神经功能缺陷评估及苏木精-伊红(HE)染色,观察缺血皮层组织形态学变化.结果:缺血再灌注组,在再灌注3～72 hHSP70 mRNA及其蛋白的表达均增加,峰值分别为161.5±4.8、160.9±4.8,与假手术组比较,差异均具有显著性(P＜0.01),但HSP70 mRNA表达较早,广泛分布于缺血侧大脑半球内,而HSP70蛋白表达以缺血侧大脑皮层为主,同时大鼠神经功能缺陷评分升高为2.28±0.47,与假手术组比较,差异均具有显著性(P＜0.01).组织形态学观察可见皮层水肿、淤血,神经细胞明显变性坏死.利多卡因能显著地促进脑缺血再灌注大鼠脑组织中HSP70 mRNA及其蛋白的表达,峰值分别为178.6±5.6、176.2±4.7,与缺血再灌注组比较,差异均具有显著性(P＜0.01),不仅HSP70蛋白表达量增多、范围增加,而且还延缓其下降,同时大鼠神经功能缺陷评分降低为1.31±0.56,缺血皮层组织形态学损伤明显减轻,与缺血再灌注组比较,差异均具有显著性(P＜0.05).结论:利多卡因的脑保护作用可能与促进HSP70的表达有关.

Objective To investigate the effects of Lidocaine on the expressions of HSP70 mRNA and HSP70 protein in cerebral cortex during transient focal cerebral ischemia-reperfusion in rats, and to discuss the possible mechanisms of its neuroprotection. Methods Sixty male Wistar rats weighing 250-300 g were randomly divided into 3 equal groups： sham operation group undergoing sham operation; ischemia/reperfusion （I/R） group undergoing thread embolism of the left middle cerebral artery occlusion （MCAO） to cause focal ischemia for 2 h and then undergoing reperfusion; and lidocaine group undergoing intravenous injection of Lidocalne in doses of 10 mg · kg^-1 10 min before MCAO, At 3, 6, 24, and 72 h after reperfusion the rats were decapitated, the expressions of HSP70 mRNA and HSP70 protein in ischemic versus nonischemic cortex were examined using in situ hybridization and immunohistochemistry. At the 24 h after reperfusion, scores of neurological deficit were estimated and changes of histomorphology in ischemic cortex were observed under the light microscope by using HE staining. Results The expressions of HSP70 mRNA and HSP70 protein in ischemic cortexes in the I/R group 3 to 72 h after reperfusion increased significantly, and the peak value of their expression was 161.5 ± 4.8 and 160. 9 ± 4.8, respectively, significantly higher than those in the sham operation group （all P〈0.01）. The expression of HSP70 mRNA appeared early and had a wide distribution in ischemic cerebral hemisphere. Whereas, the expression of HSP70 focused in ischemic cortex. The score of neurological deficit in rats in I/R group was 2.28 ± 0. 47, significantly higher than that in the sham operation group （P〈0.01）. Congestion and edema in ischemic cortex, degeneration and necrosis of neuron were observed in histomorphology in I/R group. Intravenous injection of Lidocaine enhanced significantly the expressions of HSP70 mRNA and HSP70 protein in ischemic cortex 3 to 72 h after reperfusion. The peak values of HSPT0 mRNA and HSPT0 protein expression in the Lidocaine group were 178.6±5.6 and 176.2±4.7, respectively, significantly higher than those in the I/R group （all P〈0.01）. The scores of neurological deficit and the damage of histomorphology in the lidocaine group were significantly lower than those in I/R group （all P〈0.05）. Conclusion Lidocaine can enhance the expressions of HSP70 mRNA and HSP70 protein during focal cerebral ischemia-reperfusion. This may be one of the mechanisms of its neuroprotection.