Vesicular release of glutamate from unmyelinated axons in white matter
Vesicular release of glutamate from unmyelinated axons in white matter
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DOI：
10.1038/nn1854
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发表时间：
2007-03-01
影响因子：
25
通讯作者：
Bergles, Dwight E.
中科院分区：
文献类型：
--
作者：
Ziskin, Jennifer L.;Nishiyama, Akiko;Bergles, Dwight E.
载有递质的囊泡的定向融合使中枢神经系统中的细胞间信号传导迅速，并发生在灰质内的突触处。在这里，我们表明，动作电位也诱导释放谷氨酸从轴突在胼胝体，一个白色物质区负责半球间的沟通。胼胝体轴突通过囊泡融合释放谷氨酸，这在解剖学上不同的轴-胶质突触连接处的NG 2（+）胶质祖细胞中诱导量子AMPA受体介导的电流。谷氨酸从轴突的释放促进了重复刺激，并可通过激活代谢型自身受体抑制。虽然NG 2（+）细胞与白色物质中的郎维氏结形成联系，但传导速度的测量表明，无髓鞘纤维负责NG 2（+）胶质细胞的神经元能信号传导。这种活动依赖性的谷氨酸分泌在发育和成熟的小鼠胼胝体中普遍存在，表明白色物质内的轴突既传导动作电位，又参与快速的神经元-胶质细胞通讯。
Directed fusion of transmitter-laden vesicles enables rapid intercellular signaling in the central nervous system and occurs at synapses within gray matter. Here we show that action potentials also induce the release of glutamate from axons in the corpus callosum, a white matter region responsible for interhemispheric communication. Callosal axons release glutamate by vesicular fusion, which induces quantal AMPA receptor-mediated currents in NG2(+) glial progenitors at anatomically distinct axo-glial synaptic junctions. Glutamate release from axons was facilitated by repetitive stimulation and could be inhibited through activation of metabotropic autoreceptors. Although NG2(+) cells form associations with nodes of Ranvier in white matter, measurements of conduction velocity indicated that unmyelinated fibers are responsible for glutamatergic signaling with NG2(+) glia. This activity-dependent secretion of glutamate was prevalent in the developing and mature mouse corpus callosum, indicating that axons within white matter both conduct action potentials and engage in rapid neuron-glia communication.