纳米SiO_2暴露对大鼠空间学习记忆及海马齿状回长时程增强的影响

Effect of nano-SiO_2 exposure on spatial learning and memory and LTP of hippocampal dentate gyrus in rats

目的:探讨纳米二氧化硅(nano-Si O2)对大鼠学习记忆能力的影响。方法:24只雄性SD大鼠随机分为3组(n=8):即对照组(C组),低剂量组(L组)和高剂量组(H组)。采用灌胃给药4周,干预组给予nano-Si O2颗粒混悬液,L组和H组给予剂量分别为25 mg/kg和100 mg/kg体重,对照组给予同等剂量生理盐水。每周测大鼠体重,利用Morris水迷宫检测大鼠空间学习记忆能力;在体脑立体定位电生理法检测大鼠海马齿状回LTP。结果:H组体重增幅较C组显著减小(P<0.05),L组体重增长与C组相比有减小趋势,但无统计学意义;H组大鼠在定位航行实验中逃避潜伏期明显长于同时期C组(P<0.05),而空间探索实验中目的象限游泳时间明显低于C组(P<0.05);H组LTP诱导率显著低于C组(P<0.05),高频刺激(HFS)前,组间PS峰幅值无显著差异,HFS后,L组和H组PS峰增幅均显著低于C组(P<0.05,P<0.01)。结论:nano-Si O2可能通过降低大鼠海马齿状回LTP的诱导和PS峰的增幅,进而影响大鼠学习记忆能力。

Objective： To study the effect of nano-SiO2 on spatial learning and memory. Methods： Twenty-four male rats were randomly divided into 3 groups： control group （C group）, low dose group （L group） and high dose group （H group）. The rats were intragastrically ad- ministrated with nanometer particles at 25 and 100 mg/kg body weight every day for 4 weeks. After exposure, the ability of learning and memory of rats was tested by Morris water maze, and electrephysiological brain stereotactic method was used to test long-term potentiation （LTP） in dentate gyms （DG） of the rats. Results： The increase rate of body weight in H group was reduced significantly compared with C group （ P 〈 0.05）. In the space exploration experiment of Morris water maze test, the escape latency of H group was longer than that of C group （ P 〈 0.05）. The rats of H group spent less time in finding the target quadrant （ P 〈 0.05）. The rate of LTP induction of H group was significantly lower than that of C group （P 〈 0.05）. After high fre quency stimulation （HFS）, The changes of amplitude of population spike （PS） of L group and H group were lower than those of C group significantly （ P 〈 0.05, P 〈 0.01 ）. Conclusion： Nano-SiO2 may result in impairment of spatial learning and memory ability by reducing the rate of LTP induction and the increase of PS in hippocampus.