妊娠合并糖尿病诱发胚胎先天性神经管缺陷的MAP激酶及细胞凋亡信号传导机制

目的 :探讨妊娠合并糖尿病诱发胚胎先天性神经管缺陷的分子机制。方法 :将雌性SD大鼠分为 3组 :第 1组为正常对照组 ;第 2组为streptozotocin (STZ)构建的妊娠合并糖尿病诱发先天性神经管缺陷的实验组 ;第 3组为STZ构建的糖尿病大鼠模型 ,胚胎不伴有先天性神经管缺陷。于妊娠第 1 2天取出各组胚胎 ,解剖显微镜下进行形态学分析 ;对卵黄囊细胞进行DNA片段分析 ;提取卵黄囊细胞蛋白质 ,应用特异性抗磷酸化抗体进行免疫共沉淀及Westernblot对MAPkinase(MAPK)信号途径上各蛋白激酶活性进行分析。结果 :第 2组中 ,卵黄囊细胞出现细胞凋亡特征性的DNAladder,与正常对照组相比ERK1 /2蛋白激酶活性显著下降 ;与此相反 ,JNK1 /2活性明显升高 ,凋亡相关基因caspase 3、Bax高表达 ,凋亡抑制基因AKT活性明显受抑。结论 :糖尿病诱发的胚胎先天性神经管缺陷的发生 ,与MAPkinase及细胞凋亡信号传导机制异常密切相关

MAP kinase and apoptotic signal pathways in hyperglycemia induced congenital neural tube defects

Objective:To determine molecular mechanism in hyperglycemia induced congenital neural tube defects.Methods:Three groups of Sprague Dawley rats were employed:group 1 was normal control rats with normal diet;group 2 represented streptozotocin (STZ) induced diabetic rats with congenital neural tube defects in offspring;group 3 included STZ induced diabetic rats with normal offspring.Yolk sac cells were harvested at gestational day 12 from each rat group.Changes in MAPK signaling pathways were detected by Western blot analyses using special antibodies directed against phosphorylated forms of extracellular signal regulated kinase (ERK),Jun N terminal/stress activated protein kinase (JNK/SAPK) and AKT.Apoptosis in these cells were monitored by DNA fragmented assay.In addition,expressions of pro and anti apoptotic genes were analyzed by Western blot.Results:There was strong characteristic apoptotic DNA ladder in yolk sac cells in embryopathic offspring from experimentally induced diabetic rats,and activities of ERK1/2 were dramatically decreased (group 2).In contrast,activities of JNK1/2 were significantly increased in yolk sac cells of group 2.Similarly,increased expressions of pro apoptotic caspase 3 and Bax genes were observed in yolk sac cells of the same group;whereas phosphorylated AKT was downregulated.Conclusion:MAP kinase and apoptotic signal pathways play very important roles in hyperglycemia induced neural tube defects.