Presynaptic action potential amplification by voltage-gated Na+ channels in hippocampal mossy fiber boutons
Presynaptic action potential amplification by voltage-gated Na+ channels in hippocampal mossy fiber boutons
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DOI：
10.1016/j.neuron.2004.12.048
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发表时间：
2005-02-03
期刊：
影响因子：
16.2
通讯作者：
Jonas, P
中科院分区：
文献类型：
--
作者：
Engel, D;Jonas, P
中枢神经元的动作电位在轴突初始段附近启动，传播到轴突，最后侵入突触前末梢，在那里触发递质释放。电压门控 Na+ 通道是兴奋性的关键决定因素，但皮质神经元轴突和突触前末端的 Na+ 通道密度和特性尚未得到研究。在海马苔藓纤维布顿中，Na + 通道非常丰富，估计每个布顿有 2000 个通道。突触前 Na+ 通道显示出比体细胞通道更快的失活动力学，表明同一细胞的亚细胞区室之间存在差异。对轴突-多纽扣结构中动作电位传播的计算分析表明，纽扣中的 Na+ 通道优先放大突触前动作电位并增强 Ca2+ 流入，而轴突中的 Na+ 通道控制传播的可靠性和速度。因此，突触前和轴突 Na+ 通道对苔藓纤维突触传递的贡献不同。
Action potentials in central neurons are initiated near the axon initial segment, propagate into the axon, and finally invade the presynaptic terminals, where they trigger transmitter release. Voltage-gated Na+ channels are key determinants of excitability, but Na+ channel density and properties in axons and presynaptic terminals of cortical neurons have not been examined yet. In hippocampal mossy fiber boutons, which emerge from parent axons en passant, Na+ channels are very abundant, with an estimated number of similar to2000 channels per bouton. Presynaptic Na+ channels show faster inactivation kinetics than somatic channels, suggesting differences between subcellular compartments of the same cell. Computational analysis of action potential propagation in axon-multibouton structures reveals that Na+ channels in boutons preferentially amplify the presynaptic action potential and enhance Ca2+ inflow, whereas Na+ channels in axons control the reliability and speed of propagation. Thus, presynaptic and axonal Na+ channels contribute differentially to mossy fiber synaptic transmission.