三七总皂苷对海马CA1区长时程增强效应的影响

三七总皂苷(Panax notoginseng saponins，PNS)是从传统中药三七的根中提取的主要有效成分， 具有改善血液循环、 耐缺氧、 改善记忆力、 抗衰老等多方面的生理活性。本研究采用“盲法”全细胞膜片钳技术观察PNS对大鼠海马CA1区锥体神经元长时程增强效应(LTP)的影响， 以分析其增强学习记忆功能的神经电生理机制。以断头法分离Wistar大鼠(3～4周)海马半脑， 用切片机切出400 μm厚度的海马脑片， 以全细胞电压钳制方式记录CA1区锥体细胞的兴奋性突触后电流(EPSCs)， 给予高频刺激HFS(100 Hz)诱导LTP， 分析PNS对大鼠海马CA1区EPSCs和LTP的影响。结果表明， PNS(0.1～0.4 g·L^-1)能显著抑制EPSCs(P<0.05)， 且对海马CA1区LTP无易化作用； 但PNS(0.04～0.05 g·L^-1)不影响CA1区的EPSCs基础突触传递(P>0.05)， 却可以增强HFS诱发的LTP(P<0.05)。上述结果提示， PNS(0.04～0.05 g·L^-1)能易化海马CA1区锥体神经元的长时程增强效应，该作用应是其增进学习记忆力的神经电生理机制。

Effects of Panax notoginseng saponins on long-term potentiation in the CA1 region of the rat hippocampus

Panax notoginseng saponins (PNS) are very important extracts from roots of medicinal herb Sanchi Ginseng which is highly regarded in China for its therapeutic ability to meliorate blood-circulation, anti-anoxia, improve memory, and anti-caducity effects. In this study, we used blind whole-cell voltage-clamp recordings to detect the effects of PNS on long-term potentiation (LTP) in the CA1 region of the hippocampus, and investigated the electrophysiological mechanisms underlying potentiating effects of PNS on learning and memory. Wistar rats (3-4 weeks) were decapitated and hippocampal slices (400 microm thick) were cut coronally. Excitatory postsynaptic currents (EPSCs) were recorded by patch clamp technique in whole-cell configuration. The Schaffer collateral/commissural pathway was stimulated by high frequency stimulation (HFS: 100 Hz) pulses to induce LTP. The findings showed that 0.1 - 0.4 g x L(-1) PNS significantly depressed the amplitude of EPSCs (P < 0.05) and had no facilitative effects on LTP of pyramidal neurons located in the CA1 region. PNS in the concentrations of 0.04 - 0.05 g x L(-1) did not appreciably affect the amplitude of EPSCs (P > 0.05) but markedly increased the amplitude of LTP (P < 0.05). In conclusion, 0.04 - 0.05 g x L(-1) PNS could facilitate LTP in the CA1 region of the rat hippocampus and it is reasonable to suggest that this action may contribute to its potentiating effects on learning and memory.