Wei Peng-Jv, Yao Li-Hua, Dai Dan, Huang Jun-Ni, Liu Wen-Xiao, Xiao Peng, Li Chu-Hua
School of Life Science, South China Normal University, 55 W Zhongshan Ave., Guangzhou 510631, China.
School of Life Science, South China Normal University, 55 W Zhongshan Ave., Guangzhou 510631, China.
Phytomedicine. 2015 Aug 15;22(9):807-12. doi: 10.1016/j.phymed.2015.05.008. Epub 2015 May 29.
Tenuigenin (TEN), a natural product from the Chinese herb Polygala tenuifolia root, has been reported to improve cognitive function and exhibits neuroprotective effects in pharmacological studies of the central nervous system. Synaptic transmission is the essential process of brain physiological functions such as learning and memory formation, and TEN has been shown to facilitate the basic synaptic transmission.
HYPOTHESIS/PURPOSE: Although our previous work has demonstrated that TEN is able to potentiate the basic synaptic transmission, the potential mechanism remains unclear. Here we investigated the effect of TEN on the synaptic transmission and analysed the potential mechanism. We hope that these findings will contribute to explain the role of TEN as a nootropic product or neuroprotective drug in the future.
Field excitatory postsynaptic potentials (fEPSPs), spontaneous excitatory postsynaptic currents (sEPSCs) and miniature spontaneous excitatory postsynaptic currents (mEPSCs) were recorded, by using in vitro field potential electrophysiology and whole-cell patch clamp techniques in acute hippocampal slices from rats.
TEN perfusion significantly enhanced the slope of fEPSPs and reduced the ratio of paired-pulse facilitation. Moreover, TEN increased the frequency and amplitude of sEPSCs but only improved the frequency of mEPSCs rather than amplitude in hippocampal CA1 pyramidal neurons. With removal of extracellular calcium, TEN treatment also enhanced the mEPSCs frequency without affecting amplitude. Interestingly, the increase of mEPSCs frequency caused by TEN was blocked by chelation of intracellular calcium with BAPTA-AM.
These results indicate that TEN enhances the basic synaptic transmission via stimulating presynaptic intracellular calcium.
远志皂苷元（TEN）是一种从中药远志根中提取的天然产物，在中枢神经系统的药理学研究中，已报道其可改善认知功能并具有神经保护作用。突触传递是大脑生理功能（如学习和记忆形成）的基本过程，并且已证明TEN可促进基本的突触传递。
假设/目的：尽管我们之前的研究表明TEN能够增强基本的突触传递，但其潜在机制仍不清楚。在此，我们研究了TEN对突触传递的影响并分析了潜在机制。我们希望这些发现将有助于解释TEN在未来作为益智产品或神经保护药物的作用。
采用体外场电位电生理和全细胞膜片钳技术，在大鼠急性海马脑片中记录场兴奋性突触后电位（fEPSP）、自发性兴奋性突触后电流（sEPSC）和微小自发性兴奋性突触后电流（mEPSC）。
灌注TEN可显著增强fEPSP的斜率并降低双脉冲易化率。此外，TEN增加了海马CA1锥体神经元中sEPSC的频率和幅度，但仅提高了mEPSC的频率而非幅度。去除细胞外钙后，TEN处理仍可增强mEPSC的频率而不影响幅度。有趣的是，TEN引起的mEPSC频率增加被细胞内钙螯合剂BAPTA-AM所阻断。
这些结果表明，TEN通过刺激突触前细胞内钙来增强基本的突触传递。
