锌缺乏对小鼠海马长时程增强的影响

Effect of Zinc deficiency on the formation of hippocampal long term potentiation

目的探讨锌缺乏对小鼠海马区域锌离子含量以及长时程增强(LTP)的影响。方法 3周龄CD-1小鼠饲以低锌饲料(0.85mg/kg)和去离子水5周进行实验。应用金属自显影技术(AMG)检测低锌饲料喂养对小鼠海马游离锌离子含量的影响;在小鼠海马齿状回的苔藓纤维层插入刺激电极,在CA3区锥体细胞层插入记录电极,记录高频刺激后海马苔藓纤维CA3区引起的峰电位(PS)和兴奋性突触后电位(f-EPSP)的变化,分析锌缺乏对小鼠海马LTP形成的影响。结果 AMG结果显示锌缺乏小鼠海马CA1,CA3和齿状回区域的锌离子含量明显降低(P<0.05-0.01);电生理检测结果表明锌缺乏小鼠在高频刺激后海马苔藓纤维的PS和f-EPSP均显著下降(P<0.01),提示锌缺乏抑制小鼠海马长时程增强的形成。结论锌缺乏使小鼠海马游离锌离子含量下降,参与对海马长时程增强形成的抑制。

Objective To investigate the effect of zinc deficiency on hippocampal zinc content and long term potentiation （LTP） in the mouse. Methods CD-1 mice at 3 weeks of age were fed with zinc-deficient diet （0.85mg/kg） for 5 weeks. Autometallography （AMG） was carried out to analyze the zinc content in the hippocampus. A concentric bipolar stimulating electrode was placed in the orientation of the mossy fiber lamellae of the right dentate gyrus （DG） and a glass capillary recording electrode was placed ipsilaterally in the stratum pyramidal of the CA3 region of the hippocampus. LTP was evoked by a train of high frequency stimulations （HFS）, and the changes of population spike （PS） and field excitatory postsynaptic potential （f-EPSP） were recorded, in order to analyze the effect of LTP under zinc deficiency. Results AMG staining showed that treatment with zinc-deficient diet reduced the level of zinc in hippocampal CA 1, CA3 and dentate gyrus （P〈O.05-0.01）. Electrophysiological in vivo recordings showed that zinc deficiency resulted in impairments of mossy fiber LTP （p〈0.01）. Conclusion Zinc deficiency results in a decreased level of free zinc ions in the hippocampus, which is associated with the inhibition of the formation of LTP.