低氧导致小鼠注意缺陷多动障碍样行为及其突触损伤机制

Attention deficit hyperactivity disorder-like behavior induced by hypoxia in mice and its synaptic damage mechanism

目的探讨低氧暴露导致小鼠注意缺陷多动障碍样行为及其突触损伤机制。方法随机将3周龄C57BL/6雄性小鼠分为对照组和低氧组,每组15只。低氧组置于高原环境模拟舱进行14 d低氧暴露,设置海拔高度6000 m。采用旷场实验、Y迷宫、高架十字迷宫实验观察小鼠行为;采用透射电镜观察前额叶皮质和纹状体突触超微结构;使用试剂盒检测前额叶皮质和纹状体内过氧化氢、活性氧(ROS)、丙二醛(MDA)、还原型谷胱甘肽(GSH)的含量以及谷胱甘肽过氧化物酶(GSH-PX)和总超氧化物歧化酶(T-SOD)的活性;采用实时定量PCR和Western blotting法检测前额叶皮质、纹状体中脑源性神经营养因子(BDNF)、胶质细胞源性神经营养因子(GDNF)表达。结果与对照组相比,低氧组小鼠旷场实验运动总距离和运动速度增加(P<0.01),静止时间减少(P<0.01);Y迷宫自主交替率降低(P<0.05);高架十字迷宫进入开放臂次数和探索时间无显著改变(P>0.05),僵直时间减少(P<0.05);前额叶皮质和纹状体区突触轻度肿胀、边界模糊、染色变浅;前额叶皮质和纹状体中过氧化氢、ROS、MDA含量升高(P<0.05),BDNF和GDNF的蛋白、mRNA表达下降(P<0.01);前额叶皮质GSH含量显著下降(P<0.01),GSH-PX和T-SOD活性下降(P<0.05);纹状体T-SOD活性下降(P<0.05)。结论低氧暴露可导致小鼠出现注意缺陷多动障碍样行为和突触结构损伤,与前额叶皮质和纹状体内氧化还原失衡和神经营养因子表达下降有关。

Objective To explore the attention deficit hyperactivity disorder(ADHD)-like behavior induced by hypoxia in mice and its synaptic damage mechanism.Methods The 3-week-old C57BL/6 male mice were randomly divided into control group and hypoxia group,with 15 mice in each group.The hypoxia group was placed in the high altitude simulation cabin at a simulated 6000 m altitude for 14 d of hypoxia exposure.The open field test,Y maze test and elevated plus maze test were used to observe the behavior of mice.The ultrastructure of synapses in prefrontal cortex and striatum was observed by transmission electron microscopy.The detection kits were used to detect the contents of hydrogen peroxide,reactive oxygen species(ROS),malondialdehyde(MDA)and reduced glutathione(GSH)in prefrontal cortex and striatum,as well as the activities of glutathione peroxidase(GSH-PX)and total superoxide dismutase(T-SOD).The expression levels of brain-derived neurotrophic factor(BDNF)and glial cell line-derived neurotrophic factor(GDNF)in prefrontal cortex and striatum were detected by real-time quantitative PCR and Western blotting.Results Compared with the control group,the total movement distance and movement speed of mice in hypoxia group increased in the open field test(P<0.01),and the quiescent time decreased(P<0.01).The autonomous alternation rate decreased in the Y maze test(P<0.05).In the elevated plus maze test,there was no significant change in the entering times and exploration time of open arm(P>0.05),but the freezing time decreased(P<0.05).The synapses in prefrontal cortex and striatum were slightly swollen,blurred and stained shallowly.In prefrontal cortex and striatum,the contents of hydrogen peroxide,ROS and MDA increased(P<0.05),and the protein and mRNA expressions of BDNF and GDNF decreased(P<0.01).In prefrontal cortex,the GSH content decreased significantly(P<0.01)and the activities of GSH-PX and T-SOD decreased(P<0.05).The activity of T-SOD in striatum also decreased(P<0.05).Conclusion Hypoxia exposure can lead to ADHD-like behavior and synaptic structure damage in mice,which is related to redox imbalances and decreased expression of neurotrophic factors in prefrontal cortex and striatum.