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以往的研究表明 ,在脑缺血 /再灌注的皮层和纹状体组织中信号转导与转录激活子 3 (STAT3 )被激活。本实验旨在研究SD大鼠四动脉结扎诱导的全脑缺血是否引起海马组织STAT3的快速激活及其调控机制。结果表明 ,脑缺血导致STAT3快速磷酸化激活及DNA结合活性增加。胞浆STAT3的磷酸化水平从缺血 5min起就显著增高 ,10min达高峰 (增加约 1 7倍 ) ,然后开始下降。核内STAT3的磷酸化水平则逐渐增加 ,缺血 3 0min时达高峰 (增加约2 3倍 )。电泳迁移率改变分析法显示 ,STAT3的DNA结合活性从缺血 5min起就显著增加 ,3 0min达高峰 (增加约3 2倍 )。进一步的研究表明 ,缺血前 2 0min腹腔注射给药 ,然后缺血 3 0min ,发现蛋白酪氨酸激酶抑制剂染料木黄酮和抗氧化剂N 乙酰半胱氨酸能显著地抑制核内STAT3的磷酸化水平及DNA结合活性的增加 (磷酸化水平从 2 3和2 5倍分别降为 1 2和 1 4倍 ,DNA结合活性则从 2 8和 3 7倍分别降为 1 1和 1 5倍 ) ,而蛋白酪氨酸磷酸酶抑制剂矾酸钠则能明显地促进他们的增高 (磷酸化水平从 2 0倍增到 3 4倍 ,DNA结合活性从 3 1倍增为 5 1倍 )。这些结果提示 ,蛋白酪氨酸激酶和蛋白酪氨酸磷酸酶可能共同参与了缺血诱导STAT3的激活调控 ,STAT3的激活可能有助于海马神经元适应氧化应激
Previous studies have shown that signal transducer and activator of transcription 3 (STAT3) is activated in cerebral ischemia / reperfusion cortex and striatum. The aim of this study was to investigate whether rapid global activation of STAT3 and its regulatory mechanism in hippocampus induced by global cerebral ischemia induced by ligation of four arteries in SD rats. The results showed that cerebral ischemia resulted in the rapid activation of STAT3 phosphorylation and DNA binding activity increased. The level of phosphorylation of STAT3 in cytoplasm increased significantly from 5 min after ischemia, reaching the peak at 10 min (about 1.7 fold increase), then began to decrease. The phosphorylation level of STAT3 in the nucleus gradually increased, reaching the peak at 30 min (an increase of about 23%). Electrophoretic mobility shift assay showed that the DNA binding activity of STAT3 increased significantly from 5 min after ischemia and peaked at 30 min (about 32% increase). Further studies showed that intraperitoneal injection of ischemic pretreatment 20min, then 30min ischemia, found that protein tyrosine kinase inhibitor genistein and antioxidant N acetylcysteine can significantly inhibit the nuclear STAT3 phosphorylation The level of phosphorylation and DNA binding activity increased (phosphorylation levels decreased from 12 and 14, respectively, to 12 and 14 fold, and DNA binding activity decreased from 28 and 37 fold to 11 and 15 fold, respectively) , While the protein tyrosine phosphatase inhibitor sodium vanadate significantly increased their phosphorylation levels (from 20 fold to 34 fold, DNA binding activity from 3 1 to 5 1). These results suggest that protein tyrosine kinase and protein tyrosine phosphatase may participate in the activation of STAT3 induced by ischemia, and activation of STAT3 may contribute to the adaptation of hippocampal neurons to oxidative stress