microRNA-125b在孕期酒精暴露所致新生小鼠脑神经元凋亡中的作用

目的 探讨microRNA-125b（miR125b）调控孕期酒精暴露致胚胎神经元细胞凋亡的可能机制。方法给予孕期小鼠持续连续酒精暴露［50%酒精，5 μL/（g·d）］，对照组予以0.9%NaCl暴露；检测出生小鼠脑/体重比；Tunnel法检测新生小鼠脑组织中神经元细胞凋亡情况；利用定量PCR检测miR125b、p53、凋亡基因Bax mRNA表达水平，利用Western blot检测p53及Bax蛋白表达；体外情况下给予鼠PC-12细胞酒精暴露，然后进行miR125b mimic转染以上调miR125b表达；再次检测miR125b、p53及Bax表达水平。结果与对照组相比，酒精暴露组小鼠出生脑/体重比显著降低（P<0.05），脑组织中神经元细胞凋亡增加。酒精暴露组新生小鼠脑组织中miR125b表达明显降低，而p53及Bax在mRNA和蛋白水平均显著升高（P<0.05）；PC-12细胞转染miR125b-mimic使其过表达后，miR125b表达显著升高，与酒精暴露组相比p53及Bax表达明显下降（P<0.05）。结论miR125b通过影响p53通路进而参与影响孕期酒精暴露致小鼠脑神经元凋亡。

Role of miR125b in alcohol exposure during gestation caused neuron apoptosis in newborn mice

Objective To investigate the role of miR125b in alcohol utero exposure induced neuron apoptosis. Methods Pregnant mice were exposed to alcohol (50% 5 μL/g/d) during the whole gestation and assigned as exposed group; while mice of control group were exposed to normal saline. Brain/birth weights ratio were detected. Tunnel method was applied for assessment of neuron apoptosis; and mRNA levels of miR125b, p53 and apoptosis related gene Bax were measured by Q-PCR methods. Western blot was used to detect protein levels of p53 and Bax. In vitro, PC-12 cells were exposed to ethanol, and miR125b mimic was transfected to PC-12 cells to up-regulate miR125b; and miR125b, p53 and Bax expression levels were detected. Results Brain/birth weight ratio of newborn mice in alcohol exposed group were significantly lower than those in control group (P<0.05). Neuron apoptosis level was increased in exposed group. miR125b expression was significantly reduced in exposed group; p53 and Bax were significantly increased both in mRNA and protein levels in exposed groups, compared to control group (P<0.05). miR125b mimic transfection induced over-expression of miR125b (P<0.05); thus p53 and Bax significantly decreased both in mRNA and protein levels after miR125b up-regulation after ethanol exposure (P<0.05). Conclusion Alcohol exposure during gestation may cause neuron apoptosis through decrease of miR125b, which might negative regulate p53.