High-density presynaptic transporters are required for glutamate removal from the first visual synapse
High-density presynaptic transporters are required for glutamate removal from the first visual synapse
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DOI：
10.1016/j.neuron.2006.02.022
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发表时间：
2006-04-06
期刊：
影响因子：
16.2
通讯作者：
Tachibana, M
中科院分区：
文献类型：
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作者：
Hasegawa, J;Obara, T;Tachibana, M
突触传递的可靠性不仅取决于突触间隙的释放机制和突触后反应机制，还取决于突触间隙中递质的清除或降解。越来越多的证据表明，突触后和神经胶质兴奋性氨基酸转运蛋白（EAAT）有助于谷氨酸清除。然而，突触前EAAT的作用尚不清楚。在这里，我们表明，在小鼠视网膜中，谷氨酸是从突触间隙在杆杆双极细胞（RBC）突触前EAAT，而不是突触后或胶质EAAT。药物阻断EAAT后，电刺激视杆细胞诱发的红细胞电流衰减缓慢。从EAAT亚型缺陷小鼠和EAAT偶联的阴离子电流的诱发RBC电流的记录显示，功能EAAT定位于杆终端。模型模拟表明，棒EAAT在释放位点附近密集分布，并且棒配备了几乎自给自足的谷氨酸再收集系统。
Reliable synaptic transmission depends not only on the release machinery and the postsynaptic response mechanism but also on removal or degradation of transmitter from the synaptic cleft. Accumulating evidence indicates that postsynaptic and glial excitatory amino acid transporters (EAATs) contribute to glutamate removal. However, the role of presynaptic EAATs is unclear. Here, we show in the mouse retina that glutamate is removed from the synaptic cleft at the rod to rod bipolar cell (RBC) synapse by presynaptic EAATs rather than by postsynaptic or glial EAATs. The RBC currents evoked by electrical stimulation of rods decayed slowly after pharmacological blockade of EAATs. Recordings of the evoked RBC currents from EAAT subtype-deficient mice and the EAAT-coupled anion current reveal that functional EAATs are localized to rod terminals. Model simulations suggest that rod EAATs are densely packed near the release site and that rods are equipped with an almost self-sufficient glutamate recollecting system.