Astragaloside IV inhibits spontaneous synaptic transmission and synchronized Ca2+ oscillations on hippocampal neurons.
OBJECTIVE
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 AGSIV applications. AGS-IV also decreased the peak values of the voltage-gated K+ and Na+ channel currents at that time point.


CONCLUSIONS
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.
Zhu
Shao-qing
SQ
Department of Biological Science and Biotechnology, State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing, China.
Qi
Lei
L
Rui
Yan-fang
YF
Li
Ru-xin
RX
He
Xiang-ping
XP
Xie
Zuo-ping
ZP
D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D004594:Electrophysiology; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects*; D009474:Neurons / Q000187:drug effects*; D018696:Neuroprotective Agents / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D012503:Saponins / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects*; D014315:Triterpenes / Q000494:pharmacology*
D018696:Neuroprotective Agents; D012503:Saponins; D014315:Triterpenes; C052064:astragaloside A