锌缺乏对小鼠海马长时程增强的影响

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。

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

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.