高密度突触前转运体是从第一个视觉突触清除谷氨酸所必需的。

High-density presynaptic transporters are required for glutamate removal from the first visual synapse.

作者信息

Hasegawa Jun, Obara Takehisa, Tanaka Kohichi, Tachibana Masao

机构信息

Department of Psychology, Graduate School of Humanities and Sociology, The University of Tokyo, Tokyo 113-0033, Japan.

出版信息

Neuron. 2006 Apr 6;50(1):63-74. doi: 10.1016/j.neuron.2006.02.022.

DOI:10.1016/j.neuron.2006.02.022

PMID:16600856

Abstract

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.

摘要

可靠的突触传递不仅取决于释放机制和突触后反应机制，还取决于从突触间隙清除或降解神经递质。越来越多的证据表明，突触后和胶质细胞兴奋性氨基酸转运体（EAATs）有助于谷氨酸的清除。然而，突触前EAATs的作用尚不清楚。在这里，我们在小鼠视网膜中发现，谷氨酸是通过突触前EAATs而非突触后或胶质细胞EAATs从视杆细胞到视杆双极细胞（RBC）突触的突触间隙中清除的。在药理学阻断EAATs后，电刺激视杆细胞诱发的RBC电流缓慢衰减。对EAAT亚型缺陷小鼠诱发的RBC电流和EAAT偶联阴离子电流的记录表明，功能性EAATs定位于视杆细胞终末。模型模拟表明，视杆细胞EAATs在释放位点附近密集分布，并且视杆细胞配备了一个几乎自给自足的谷氨酸回收系统。