Kinetics and regulation of fast endocytosis at hippocampal synapses
Kinetics and regulation of fast endocytosis at hippocampal synapses
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DOI：
10.1038/29079
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发表时间：
1998-08-06
期刊：
影响因子：
64.8
通讯作者：
Tsien, RW
中科院分区：
文献类型：
--
作者：
Klingauf, J;Kavalali, ET;Tsien, RW
突触前神经末梢通常含有少至100个囊泡（1，2），因此在胞吐作用后必须很快回收它们，以在重复放电期间保持突触传递和突触前形态（3，4）。因此，研究了囊泡内吞和再引发的动力学（3，4）和机制（5）。海马神经末梢中的囊泡可以在类似于前一轮胞吐的40秒内释放其内容物（6，7）。使用苯乙烯基染料FM 1 -43的研究（参考文献3）估计内吞作用的时间常数与20-30 s相似（参考文献4，8），至少是总再循环时间的一半，这比其他分泌系统中的内吞作用慢得多（参考文献9-11）。这似乎是矛盾的，神经分泌终端，可以受益最多的快速内吞不使用这样的机制。在这里，我们证明了在海马神经末梢的快速内吞作用的存在，并得出其动力学从荧光测量使用染料与不同速率的膜去分区。暴露于星形孢菌素或细胞外钙升高后，囊泡检索的快速模式快得多。因此，海马突触利用有效的内吞机制，其囊泡回收受到调节控制。
Presynaptic nerve terminals often contain as few as a hundred vesicles(1,2) and so must recycle them soon after exocytosis to preserve synaptic transmission and presynaptic morphology(3,4) during repetitive firing. The kinetics(3,4) and mechanisms(5) of vesicular endocytosis and repriming have therefore been studied. Vesicles in hippocampal nerve terminals can become available to release their contents within similar to 40 s of the previous round of exocytosis(6,7). Studies using the styryl dye FM1-43 (ref. 3) have estimated the time constant for endocytosis as similar to 20-30 s (refs 4, 8), at least half of the total recycling time, which is much slower than endocytosis in other secretory systems(9-11). It seems paradoxical that the neurosecretory terminals that could benefit the most from rapid endocytosis do not use such a mechanism. Here we demonstrate the existence of fast endocytosis in hippocampal nerve terminals and derive its kinetics from fluorescence measurements using dyes with varying rates of membrane departitioning. The rapid mode of vesicular retrieval was much faster after exposure to staurosporine or elevated extracellular calcium. Thus hippocampal synapses take advantage of efficient mechanisms for endocytosis, and their vesicular retrieval is subject to modulatory control.