Possibility of multiquantal transmission at single inhibitory synapse in cultured rat hippocampal neurons
Possibility of multiquantal transmission at single inhibitory synapse in cultured rat hippocampal neurons
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DOI：
10.1016/s0306-4522(99)00084-6
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发表时间：
1999-01-01
期刊：
影响因子：
3.3
通讯作者：
Veselovsky, NS
中科院分区：
文献类型：
--
作者：
Fedulova, SA;Vasilyev, DV;Veselovsky, NS
采用全细胞膜片钳技术在突触连接的培养海马神经元上研究了-75 mV保持电位下的微型、自发和诱发抑制性突触后电流。所有实验均在含河豚毒素的溶液中进行，以排除动作电位的产生。在无Ca2+溶液中观察到自发的微型抑制性突触后电流。微型抑制性突触后电流的分布向较大的电流幅值倾斜，可以用一个高斯分布可靠地拟合，其平均值为10.0 +/- 1.2 pA （n = 7）。在生理溶液（Ca2+ 2 mM）中记录自发发生的全细胞自发抑制性突触后电流。自发电流的平均振幅取决于膜电位，并在- 18 +/- 5 mV （n = 5）时反转。自发性抑制性突触后电流的振幅分布有一个明显的峰值，平均为20.0 +/- 2.0 pA （n = 6）或10.0 +/- 2.0 pA （n = 2）。抑制性突触后刺激诱发电流产生于通过短去极化脉冲直接胞外电刺激单个突触前钮扣逐渐激活神经递质释放的反应。抑制性突触后电流的平均振幅的电流-电压关系是线性的，并且在对应细胞内和细胞外Cl-浓度的能斯特方程预测的电位上是反向的。微型、自发和诱发抑制性突触后电流的衰减时间过程用两个指数和拟合，其时间常数在标准差范围内相同。刺激诱发的抑制性突触后电流在所有研究的突触中以其峰值振幅的离散等值值波动，从可测量的最小值约8 pA到200 pA。所诱发的抑制性突触后电流被假定为统计上独立的量子事件的叠加。用几条高斯曲线拟合诱发抑制性突触后电流的振幅直方图，得到与20 +/- 3 pA （n = 10）的平均距离相等的峰，并假设其为一个量子（量子大小）来构建泊松分布。探讨了大鼠海马神经元单抑制突触同时多量释放的可能性。(c) 1999年ibro。Elsevier Science Ltd.出版。
Miniature, spontaneous and evoked inhibitory postsynaptic currents were studied using the whole-cell patch-clamp technique on synaptically connected cultured hippocampal neurons, at a holding potential of -75 mV. All experiments were done in tetrodotoxin-containing solution to exclude an action potential generation. Spontaneous miniature inhibitory postsynaptic currents were observed in Ca2+-free solution. The distribution of miniature inhibitory postsynaptic currents was skewed to larger current amplitudes and could be fitted reliably by one Gaussian with the mean at 10.0 +/- 1.2 pA (n = 7). Spontaneously occurring whole-cell spontaneous inhibitory postsynaptic currents were recorded in physiological solution (Ca2+ 2 mM). The average amplitude of spontaneously occurring currents depended on membrane potential and reversed at - 18 +/- 5 mV (n = 5). The amplitude distribution of spontaneous inhibitory postsynaptic currents had one peak clearly delectable with the mean of 20.0 +/- 2.0 pA (n = 6) or 10.0 +/- 2.0 pA (n = 2). inhibitory postsynaptic stimulus-evoked currents arose in responses to gradual activation of neurotransmitter release by direct extracellular electrical stimulation of a single presynaptic bouton by short depolarizing pulses. The current-voltage relation of the averaged amplitudes of evoked inhibitory postsynaptic currents was linear and reversed at potential predicted by the Nernst equation for corresponding intra- and extracellular Cl- concentrations. The time-course of decay of miniature, spontaneous and evoked inhibitory postsynaptic currents was fitted by a sum of two exponents and their time-constants were the same in the range of standard deviation. The stimulus-evoked inhibitory postsynaptic currents fluctuated with regard to the discrete aliquot values of their peak amplitudes in all the investigated synapses from a measurable minimum of about 8 pA to 200 pA. The evoked inhibitory postsynaptic currents were assumed as superimposition of statistically independent quantal events. Fitting amplitude histograms of evoked inhibitory postsynaptic currents with several Gaussian curves resulted in peaks that were equidistant with the mean space of 20 +/- 3 pA (n = 10), which was assumed as one quantum (quantum size) to construct the Poisson's distribution.A possibility of simultaneous multiquantal release at single inhibitory synapses of rat hippocampal neurons was discussed. (C) 1999 IBRO. Published by Elsevier Science Ltd.