Astragaloside IV inhibits spontaneous synaptic transmission and synchronized Ca2+ oscillations on hippocampal neurons1

Authors

  • Shao-qing ZHU,

    1. Department of Biological Science and Biotechnology, State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China
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  • Lei QI,

    1. Department of Biological Science and Biotechnology, State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China
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  • Yan-fang RUI,

    1. Department of Biological Science and Biotechnology, State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China
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  • Ru-xin LI,

    1. Department of Biological Science and Biotechnology, State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China
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  • Xiang-ping HE,

    1. Department of Biological Science and Biotechnology, State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China
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  • Zuo-ping XIE

    Corresponding author
    1. Department of Biological Science and Biotechnology, State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China
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  • 1

    This work was supported by a grant from the Major State Basic Research Development Program of China (973 Program) (No 2005CB522503) and the Natural Science Foundation of Beijing (Grant No 5052015).

Correspondence to Prof Zuo-ping XIE. Phn 86-10-6278-8677. Fax 86-10-6277-2271. E-mail zuopingx@mail.tsinghua.edu.cn

Abstract

Aim: To investigate the changes in the spontaneous neuronal excitability induced by astragaloside IV (AGS-IV) in the cultured hippocampal network. Methods: Hippocampal neurons in culture for 9-11 d were used for this study. The spontaneous synaptic activities of these hippocampal neurons were examined by Ca2+ imaging and whole-cell patch-clamp techniques. In total, 40 mg/L AGS-IV dissolved in DMSO and 2 mL/L DMSO were applied to the neurons under a microscope while the experiments were taking place. Results: AGS-IV inhibited the frequencies of synchronized spontaneous Ca2+ oscillations to 59.39%±3.25% (mean±SEM), the spontaneous postsynaptic currents to 43.78%±7.72% (mean±SEM), and the spontaneous excitatory postsynaptic currents to 49.25%±7.06% (mean±SEM) of those of the control periods, respectively, at 16 min after the AGS-IV applications. AGS-IV also decreased the peak values of the voltage-gated K+ and Na+ channel currents at that time point. Conclusion: These results indicate that AGS-IV suppresses the spontaneous neuronal excitabilities effectively. Such a modulation of neuronal activity could represent new evidence for AGS-IV as a neuroprotector.

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