丙泊酚预处理对大鼠心肌缺血/再灌注损伤中自噬潮的影响

目的 研究丙泊酚预处理对大鼠心肌缺血/再灌注(ischemia/reperfusion,I/R)期间自噬潮的影响及其机制. 方法 采用大鼠在体心肌I/R损伤模型,将90只雄性SD大鼠按照随机数字表法分为5组(每组18只):①假手术组(Sham组),只穿线不结扎;②I/R组;③丙泊酚预处理组(P+I/R组);④Ⅰ型磷脂酰肌醇3-激酶(phosphatidylinositol 3-kinase,PI3K)抑制剂A66预处理组(A+I/R组);⑤丙泊酚+A66预处理组(P+A+I/R组).采用结扎冠状动脉左前降支的方法制备心肌I/R模型.除Sham组外,其余各组均缺血30 min,再灌注120 min.缺血前15 min,P+I/R组通过股静脉输注丙泊酚15 mg·kg1·h1;A+I/R组缺血前1h腹腔注射A66溶液10 mg/kg;P+A+I/R组在缺血前1h腹腔注射A66溶液10 mg/kg,缺血前15 min再通过股静脉输注丙泊酚15 mg·kg1·h-1.模型制备后取心肌,2,3,5-氯化三苯基四氮唑(2,3,5-triphenyhetrazolium chloride,TTC)法染色并计算梗死面积百分比,酶标法测定乳酸脱氢酶(lactate dehydwgenase,LDH)活性,Western bolt法检测微管相关蛋白1轻链3(microtubule-associated protein 1 light chain 3,LC3)-Ⅱ、P62蛋白的表达量,电子显微镜定性观察自噬体、自噬溶酶体的数量.结果 与I/R组比较,P+I/R组与P+A+I/R组梗死面积[(50.1±-3.9)％比(26.5±1.3)％、(42.6±1.9)％]显著减小(P＜0.05),血清LDH活性降低,LC3-Ⅱ表达水平降低,P62表达水平升高(P＜0.05),自噬体、自噬溶酶体明显减少.与P+I/R组比较,P+A+I/R组梗死面积[(26.5±1.3)％比(42.6±1.9)％]显著增加(P＜0.05),血清LDH活性升高,LC3-Ⅱ表达水平升高,P62表达水平降低(P＜0.05),自噬体、自噬溶酶体增加. 结论 丙泊酚预处理激活PI3K/蛋白激酶B(pmtein kinase B,Akt)通路,抑制I/R心肌中自噬潮进行,对大鼠心肌I/R损伤产生保护作用.

Effects of propofol preconditioning on autophagy flux in myocardial ischemia/reperfusion injury of rats

Objective To study the effects of propofol preconditioning on autophagy flux in myocardial ischemia/reperfusion (I/R) injury of rats and its possible mechanism.Methods Using myocardial ischemia/reperfusion injury model in vivo,90 healthy adult male SD rats of 280-350 g were randomly divided into 5 groups(n=18):sham surgery group (Sham group),only threaded without deligation,I/R group,propofol preconditioning group (P+I/R group),phosphatidylinositol 3-kinase(PI3K) inhibitor A66 preconditioning group (A+I/R group),propofol and A66 preconditioning group (P+A+I/R group).I/R model was achieved by ligating the anterior descending branch of the left coronary artery.Each group underwent 30 min ischemia and then 120 min reperfusion except Sham group.Fifteen mg· kg-1· h-1 Propofol is infused iv in P+I/R group.Ten mg/kg A66 is infused ip in A+I/R group.Myocardial infarct size and lactate dehydrogenase (LDH) levels were examined by 2,3,5-triphenyltetrazolium chloride (TTC) staining and Enzyme standard method at 120 min of reperfusion.Expressions of microtubule-associated protein 1 light chain 3(LC3)-Ⅱ and P62 were determined by Western blot.Autophagosome and autophagolysosome were determined by TEM.Results Compared with I/R group,myocardial infarct size [(50.1±3.9)％ vs (26.5±1.3)％,(42.6±1.9)％](P＜0.05),LC3-Ⅱ and LDH level in P+I/R group was decreased,P62 was increased (P＜0.05).The number of autophagosome and autophagolysosome was significantly decreased.Compared with P+I/R group,myocardial infarct size[(26.5±1.3)％ vs (42.6±1.9)％](P＜0.05),LC3-Ⅱ and LDH levels were increased in P+A+I/R group(P＜0.05).The number of autophagosome and autophagolysosome was increased.Conclusions Propofol preconditioning can inhibit autophagy flux by activating PI3K/protein kinase B (Akt) pathway during I/R in rat hearts,which may play a role in its cardioprotective mechanism duringI/R injury.