高原低氧环境对小鼠海马神经元自噬的影响及意义

摘要

目的 研究6000 m海拔高度下,不同时长的高原低氧暴露对小鼠负性情绪、海马神经元损伤、海马神经元自噬的影响,探讨其相互关系.方法 利用低压氧舱模拟6000 m海拔高原低氧环境,实验组给予不同时长的高原低氧处理,对照组置饲养子舱外.采用高架十字迷宫实验评估高原低氧环境对小鼠负性情绪的影响,HE染色观察海马神经元病理学变化,Western Blot法检测低氧诱导因子-1α(HIF-1α)及自噬标志性蛋白Beclin-1和微管相关蛋白1轻链3-Ⅱ(LC3-Ⅱ)在海马组织的表达变化.结果 高原低氧1、3、14 d暴露明显减少了小鼠高架十字迷宫开臂滞留时间百分比和开臂进入次数百分比;HE染色显示,高原低氧1、3、14 d组小鼠海马CA1区的神经元排列紊乱、细胞间隙变大、胞体不规则、核固缩表现明显,而高原低氧7d组海马CA1区神经元的损伤表现相对较轻;WesternBlot结果显示,海马HIF-1α、Beclin-1及LC3-Ⅱ的表达在高原低氧暴露1d后即达到高峰,后逐渐下降.至高原低氧处理第7天,HIF-1α和LC3-Ⅱ表达与对照组已无显著差异.结论 高原低氧环境下,小鼠负性情绪的增加与海马神经元的损伤密切相关,而自噬的激活可能参与了急性高原低氧期海马神经元的损伤.%Objective This study aims to investigate the influence of high-altitude (6000 m) hypoxia exposure for different duration on negative emotions and hippocampal neuronal injury and autophagy of mouse and their interrelation.Methods Hypobaric oxygen chamber was used to simulate 6000 m altitude circumstances.Treatment groups were exposed to high-altitude hypoxia circumstances for different time,and control group was raised outside the hypobaric oxygen chamber.Elevated plus maze (EMP) test was used to investigate the negative emotions after high-altitude hypoxia exposure.The pathological morphology of hippocampal neurons in CA1 area was examined by HE staining.Expressions of hypoxia-inducible factor 1α (HIF-1α),Bcelin-1 and microtubule-associated protein 1 light 3-Ⅱ (LC3-Ⅱ) was assayed by Western Blot.Results Significant reductions after high altitude hypoxia exposure for 1,3,and 14 d in the percentage of residence time and the entries in the open arms indicated by EMP test was observed.HE staining showed that the hippocampal neurons in CA1 area after high-altitude hypoxia exposure for 1,3,and 14 d were arranged disorderly,with dilatate intercellular spaces and irregular shape and karyopyknosis.And compared with other treatment groups,injury of hippocampal neurons after 7 d high-altitude hypoxia exposure was attenuated relatively.The expressions of HIF-1α,Beclin-1 and LC3-Ⅱ peaked after high altitude hypoxia exposure for 1 d and then decreased.At treatment for 7 d,there were no significant difference in the expressions of HIF-1α and LC3-Ⅱ compared with the control group.Conclusion At high-altitude hypoxia circumstances,increased negative emotions of mouse were related with the damage of hippocampal neurons,and the activation of autophagy may be involved in the damage of hippocampal neurons.