丙泊酚保护脑缺血再灌注损伤可能与缝隙连接功能的抑制相关

摘要

目的：探讨丙泊酚对脑缺血再灌注损伤的保护作用与缝隙连接的关系及其可能机制。方法70只雄性SD大鼠随机分为假手术（sham）组、缺血再灌注（I/R）组、丙泊酚低剂量（P25，25 mg/kg）组、中剂量（P50，50 mg/kg）组、高剂量（P100,100 mg/kg）组、甘珀酸（CBX）干预缺血再灌注（I/R+CBX）组和甘珀酸干预丙泊酚高剂量（P100+CBX）组。采用线栓法制备大鼠大脑中动脉栓塞（MCAO）模型，脑缺血2 h，再灌注24 h；采用Longa's法对大鼠进行神经行为学评分；TTC染色法检测脑梗死体积的变化；Western blot法检测缝隙连接蛋白43（Cx43）、蛋白激酶C（PKC）以及凋亡相关因子Bax、Bcl-2的蛋白表达变化。结果与缺血再灌注组相比，除丙泊酚低剂量组外，丙泊酚中、高剂量组神经功能缺损评分和脑梗死体积百分率均明显降低，且高剂量组效果更佳；甘珀酸可以进一步增强丙泊酚对大鼠脑缺血再灌注损伤的保护作用。Western blot结果显示，与sham组相比，I/R组Cx43蛋白表达以及Bax与Bcl-2比值显著增高，而PKC蛋白表达明显降低；丙泊酚高剂量组较I/R组Cx43蛋白表达及Bax与Bcl-2比值明显降低，PKC蛋白表达显著增多；且甘珀酸可以使丙泊酚的这一作用增强。结论丙泊酚预处理可减轻I/R损伤，其机制可能与通过PKC信号通路抑制缝隙连接功能及降低Bax/Bcl-2的比值有关。%Objective To investigate the protective effect of propofol against focal cerebral ischemia/reperfusion (I/R) injury in rats and its relation with gap junction. Methods Seventy adult male SD rats were randomly divided into sham-operated group, I/R group, low-, moderate-, and high-dose propofol groups (25, 50, 100 mg/kg;P25, P50, P10 groups, respectively), I/R+CBX group and P10+CBX group. Thread occlusion was used to induce middle cerebral artery occlusion (MCAO) in the mice for 2 h followed by reperfusion for 24 h. Longa's scores were used to evaluate the neurological behavior of the rats. TTC staining was used to measure the cerebral infarction volume and Western blotting was performed to detect the expressions of Cx43, PKC, Bax, and Bcl-2 in the brain of the rats. Results Compared with the I/R group, the rats pretreated with moderate and high doses of propofol showed significantly reduced neurological behavior scores and cerebral infarction volume percentage, and the effect was more obvious in high-dose propofol pretreatment group. CBX obviously enhanced the protective effect of propo-fol against I/R injury. Compared with those in the sham-operated group, the protein expression of Cx43 and the Bax/Bcl-2 ratio were increased and the protein expression of PKC was reduced in I/R group, and these changes were significantly reversed by high-dose propofol pretreatment;the effects of propofol were further enhanced by CBX. Conclusion The protective effect of propofol against cerebral I/R injury may involve the inhibition of the gap junction via PKC signaling and by reducing the Bax/Bcl-2 ratio.