小鼠海马CAl区高频刺激诱发的突触可塑性分析

通过细胞外记录方法记录场兴奋性突触后电位（field excitatory postsynaptic potential,fEPSP）的变化是研究突触可塑性,诸如长时程增强（long-term potentiation,LTP）和双脉冲可塑性（paired-pulse plasticity,PPP）的最常见方法之一。fEPSP波形的起始斜率、起始面积、峰值及总面积等的变化常用作判断突触可塑性增强或减弱的标准。在相同记录结果中测量fEPSP波形不同部位通常会有不同的结果,因此可能得出不同的结论,这些往往会被研究者忽略。本文通过测量小鼠海马CA1区细胞fEPSP波形的起始斜率、起始面积、峰值、总面积及时间参数等,分析比较高频刺激（high-frequency stimulation,HFS）诱发的突触可塑性,包括LTP和PPP的变化。结果显示,LTP过程中AMPA受体动力学变化加快,且在同一记录中,fEPSP波形不同部位的测量分析可以产生较大幅度的LTP和PPP差异。给予HFS后,双脉冲诱发fEPSP的比率在测量起始面积时略有下降,但在测量起始斜率时则显著增加,这些结果可能导致相反的结论。因此,全面仔细地分析fEPSP波形在整个实验中的变化对正确了解突触可塑性至关重要。

Analysis of high-frequency stimulation-evoked synaptic plasticity in mouse hippocampal CA1 region

Extracellular recordings of field excitatory postsynaptic potential (fEPSP) is one of the most common ways for studies ofsynaptic plasticity, such as long-term potentiation (LTP) and paired-pulse plasticity (PPP). The measurement of the changes in thedifferent components of fEPSP waveform, such as the initial slope, initial area, peak amplitude and whole area, were commonly usedas criteria for the judgement of potentiation or depression of synaptic plasticity. However, the differences in the conclusions drawnfrom measuring different components of fEPSP waveform at the same recording have still been largely ignored. Here we compared high-frequency stimulation (HFS)-evoked synaptic plasticity, both LTP and PPP, by measuring different components of fEPSP waveform,including the initial slope, initial area, peak amplitude, whole area and time course. The results not only indicated the acceleration of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor kinetics underlies LTP in hippocampal CAI region of mice,but also showed that different measurements of fEPSP waveform at the same recording'result in different magnitudes of LTP anddifferent forms of PPP in hippocampal CAl region of mice. After HFS, the paired-pulse ratio was slightly decreased by measurementof the initial area, but obviously increased by measurement of the initial slope of the pair fEPSPs. These results might draw apparentlycontradictory conclusions. Therefore, careful and complete analysis of the data from different parts of fEPSP waveforms is importantfor reflection of the faithful changes in synaptic plasticity.