JAK2/STAT3通过上调Bcl-2蛋白介导TTX心肌保护作用

Mediation of JAK2/STAT3 pathway on myocardial protection of tetrodotoxin cardioplegia in rat hearts via upregulating the protein expression of Bcl-2

目的:研究JAK2/STAT3信号通路在河豚毒素(Tetrodotoxin,TTX)心脏停搏液心肌保护中的作用。方法:24只Wistar大鼠随机分为对照组、TTX组和TTX+AG490组,每组8只。对照组:开胸取左心室肌作为缺血前对照。TTX组:建立离体心脏Langendorff-Neely灌注模型,预灌注K-H缓冲液30min后,灌注4℃TTX心脏停搏液,停搏心脏并低温维持60min,复灌K-H缓冲液60min后,取左心室肌备用。TTX+AG490组:操作同TTX组,但预灌和复灌时均在K-H缓冲液中加入JAK2抑制剂AG490(5μmol/L)。采用免疫组化法测定心肌组织中p-STAT3(磷酸化STAT3)和Bcl-2表达量(Protein expression index,PEI),TUNEL检测心肌细胞凋亡指数(Apoptosis index,AI),比较2组间的变化。结果:与对照组相比,TTX组和TTX+AG490组心肌组织中p-STAT3和Bcl-2的表达量均明显增加(P<0.05);予以AG490处理后,p-STAT3和Bcl-2的表达量较TTX组明显下降(P<0.05)。Bcl-2蛋白表达与p-STAT3蛋白表达呈正相关(r=0.743,P<0.05)。经历缺血再灌注后,TTX组和TTX+AG490组心肌细胞AI明显高于对照组(P<0.05);与TTX组相比,TTX+AG490组AI显著增加(P<0.05)。结论:JAK2/STAT3信号通路通过上调Bcl-2的表达,抑制心肌细胞凋亡,介导TTX心脏停搏液对缺血心肌的保护作用。

Objective：To investigate the effect of JAK2/STAT3 pathway on myocardial protection of tetrodotoxin （TTX） cardioplegia in rat hearts. Methods：A total of 24 Wistar rats were randomly divided into Group Control,Group TTX and Group TTX＋AG490（n=8）. The left ventricular samples in Group Control were collected as pre-ischemia control through thoracotomy. After isolated heart Langendorff and Neely models were established, the rat hearts in Group TTX were continuously perfused with Krebs-Henseleit（K-H） buffer solution for 30 minutes, arrested by TTX cardioplegia（4℃） for 60 minutes,and underwent reperfusion with K-H buffer solution for 60 minutes,then the left ventricular samples were collected for detections. The rat hearts in Group TTX＋AG490 were perfused and reperfused with JAK2 inhibitor AG490（5μmol/L） and K-H buffer solution under the same procedure as Group TTX. The protein expression indexes（PEI） of phosphorylated-STAT3（p-STAT3） and B-cell lymphoma-2（ Bcl-2 ） in myocardium were detected by immunohistochemical assay（IHC ）. The apoptosis index（AI ） of cardiomyocyte was detected by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling（TUNEL）. The changes of these indexes in three groups were used for comparison. Results：Compared with Group Control,the PEI of p-STAT3 and Bcl-2 in Group TTX and Group TTX＋AG490 increased significantly（P〈0.05）;Treated with AG490,the PEI of p-STAT3 and Bcl-2 in Group TTX＋AG490 was lower than that in Group TTX（P〈0.05）. The PEI of Bcl-2 had a positive correlation with the PEI of p-STAT3 （r=0.743,P〈0.05）. After ischemia/reperfusion,AI in Group Trx and Group TTX＋AG490 were significantly higher than that in Group Control（P〈0.05）;compared with Group TTX,AI in Group TTX＋AG490 increased significantly（P〈0.05）. Conclutions：JAK2/STAT3 pathway could mediate myocardial protection of TTX cardioplegia in rat hearts via upregulating the protein expression of Bcl-2 and suppressing cardiomyocytes apoptosis.