MEF2A在创伤后应激障碍小鼠内侧前额叶皮质中的变化及功能研究

Changes of myocyte enhancer factor 2A in medial prefrontal cortex and their function in mice with posttraumatic stress disorder

目的研究单一延长刺激+足部电击法制作的创伤后应激障碍(PTSD)模型小鼠内侧前额叶皮质(mPFC)椎体神经元树突、MEF2A的变化及其潜在功能。方法C57BL/6N小鼠60只按随机数字表法分为模型组和对照组,每组30只。模型组小鼠采用单一延长刺激+足部电击法制作PTSD模型,对照组小鼠在造模过程中断食断水,无其他应激处理。造模后14d取2组小鼠各10只,采用旷场实验及高架十字实验检测小鼠的行为学表现,高尔基染色检测小鼠mPFC神经元形态、树突总长度及树突棘密度。造模后1d、4d、7d、14d每组取5只小鼠,采用实时定量PCR检测小鼠mPFC中Arc及SynGAPrnmA的表达,Western blotting实验检测小鼠mPFC中肌细胞增强因子2A(MEF2A)、P38蛋白及其磷酸化水平。结果(1)与对照组比较,模型组小鼠进入中央区域的次数、运动总距离减少,差异均有统计学意义(P<0.05)。与对照组比较,模型组小鼠进入开臂区域的次数、在开臂区域的时间占比减少,差异均有统计学意义(P<0.05)。与对照组比较,模型组小鼠mPFC中神经元的树突总长度较短、树突棘密度较低,差异均有统计学意义(P<0.05)。(2)造模后1 d、4d、7d、14d模型组小鼠mPFC中SynGAP、Arc mRNA,磷酸化MEF2A.P38蛋白的表达较对照组升高,差异均有统计学意义(P<0.05)。造模后4d及7d模型组小鼠mPFC中SynGAP、Arc mRNA高于造模后ld、14d,,造模后4d及14d模型组小鼠mPFC中磷酸化MEF2A蛋白的表达高于造模后1d、7d,造模后7d及14d模型组小鼠mPFC中磷酸化P38蛋白的表达高于造模后1d、4d,差异均有统计学意义(P<0.05)。结论在PTSD小鼠模型中,MEF2A的转录激活参与了mPFC椎体神经元树突棘数目的减少。

Objective To investigate the neural dendritic spines variation and myocyte enhancer factor 2A(MEF2A)changes in the medial prefrontal cortex(mPFC)and their function in posttraumatic stress disorder(PTSD)mouse models established by single prolonged stress&electiic foot shock(SPS&S).Methods A total of 608-week-old male C57BL/6N mice were selected and randomly divided into control and treatment groups(n=30).PTSD mouse models in the treatment group were established by SPS&S;mice in the control group were deprived of food and water during the modeling process without other stress treatment.Ten mice were taken from each group 14 d after modeling,and anxiety and fear behaviors in mice were evaluated by open field test and elevated plus-maze test;the morphology of mPFC neurons,total length of dendrites and density of dendrite spines were determined by Golgi staining.Five mice were selected from each group one,4,7 and 14 d after modeling;real-time quantitative PCR was used to detect the mRNA expressions of Arc and SynGA P in mouse mPFC,and Western blotting was used to detect the proteins levels of MEF2A,P3&phosphorylated-(p-)MEF2A,and p-P38 in mouse mPFC.Results(1)As compared with those in the control group,the number of times entering the central region was significantly smaller and the total distance of movement was statistically decreased in mice of the treatment group(P<0.05);as compared with those in the control group,the number of times entering the open arm region was significantly smaller and the proportion of time spending in the open arm region was statistically decreased in the treatment group(P<0.05).The total length of neurons in mPFC was significantly shorter and the density of dendrites was significantly lower in the treatment group than those in the control group(P<0.05).(2)The Arc and SynGAP mRNA expressions,and p-MEF2A and p-P38 protein expressions in mPFC of mice in treatment group one,4,7 and 14 d after modeling were significantly increased as compared with those in control group(P<0.05);in treatment group,the A rc and SynGA P mRNA expressions 4 and 7 d after modeling were significantly higher than those one and 14 d after modeling,and p-MEF2A expressions in mPFC 4 and 14 d after modeling were significantly higher than those one and 7 d after modeling(P<0.05);and p-P38 protein expressions in mPFC 7 and 14 d after modeling were significantly higher than those one and 4 d after modeling(P<0.05).Conclusion In PTSD mouse models established by SPS&S,transcriptional activation of MEF2A involves in dendritic spines number reduction in the pyramidal neurons of mPFC.