Chen Xiaoke, Wang Liecheng, Zhou Yang, Zheng Liang-Hong, Zhou Zhuan
Institute of Molecular Medicine, Peking University, Beijing 100871, China.
J Neurosci. 2005 Oct 5;25(40):9236-43. doi: 10.1523/JNEUROSCI.1640-05.2005.
Under physiological conditions, astrocytes not only passively support and nourish adjacent neurons, but also actively modulate neuronal transmission by releasing "glial transmitters," such as glutamate, ATP, and D-serine. Unlike the case for neurons, the mechanisms by which glia release transmitters are essentially unknown. Here, by using electrochemical amperometry and frequency-modulated single-vesicle imaging, we discovered that hippocampal astrocytes exhibit two modes of exocytosis of glutamate in response to various stimuli. After physiological stimulation, a glial vesicle releases a quantal content that is only 10% of that induced by nonphysiological, mechanical stimulation. The small release event arises from a brief (approximately 2 ms) opening of the fusion pore. We conclude that, after physiological stimulation, astrocytes release glutamate via a vesicular "kiss-and-run" mechanism.
在生理条件下，星形胶质细胞不仅被动地支持和滋养相邻的神经元，还通过释放“胶质递质”（如谷氨酸、三磷酸腺苷和D-丝氨酸）来积极调节神经元传递。与神经元不同，胶质细胞释放递质的机制基本上还不清楚。在这里，通过使用电化学安培法和调频单囊泡成像，我们发现海马星形胶质细胞在受到各种刺激时表现出两种谷氨酸胞吐模式。生理刺激后，一个胶质囊泡释放的量子含量仅为非生理机械刺激诱导量的10%。小释放事件源于融合孔的短暂（约2毫秒）开放。我们得出结论，在生理刺激后，星形胶质细胞通过囊泡“亲吻-逃离”机制释放谷氨酸。
