Matsui Ko, Jahr Craig E, Rubio Maria E
Vollum Institute, Oregon Health and Science University, Portland, Oregon 97239, USA.
J Neurosci. 2005 Aug 17;25(33):7538-47. doi: 10.1523/JNEUROSCI.1927-05.2005.
Until recently, communication from neurons to astrocytes was thought to be mediated by low-concentration transients of glutamate caused by spillover from the synaptic cleft. However, quantal events recorded in rat cerebellar Bergmann glial cells (BGs) have fast kinetics, comparable with those recorded in neurons. By combining outside-out patch recordings of BG AMPA receptors and quantitative electron microscopic analysis of glutamate receptor subunit 1 (GluR1) and GluR4 immunogold labeling measurements, at both the soma and membranes surrounding synapses, we estimate the absolute density of functional AMPA receptors. Using a kinetic model of BG AMPA receptors, we find that quantal events recorded in BGs are produced by high-concentration (approximately 1-1.5 mM), fast transients (approximately 0.5 ms decay) of glutamate, similar to transients within the synaptic cleft. Our results indicate that neural signaling to BGs is mediated by ectopic release of transmitter from presynaptic elements directly facing the BG membrane.
直到最近，人们一直认为神经元与星形胶质细胞之间的通讯是由突触间隙溢出引起的低浓度谷氨酸瞬变介导的。然而，在大鼠小脑伯格曼胶质细胞（BGs）中记录到的量子事件具有快速动力学，与在神经元中记录到的相当。通过结合BG AMPA受体的外向膜片钳记录以及对谷氨酸受体亚基1（GluR1）和GluR4免疫金标记测量的定量电子显微镜分析，在胞体和突触周围膜上，我们估计了功能性AMPA受体的绝对密度。使用BG AMPA受体的动力学模型，我们发现BGs中记录到的量子事件是由高浓度（约1-1.5 mM）、快速瞬变（约0.5 ms衰减）的谷氨酸产生的，类似于突触间隙内的瞬变。我们的结果表明，向BGs的神经信号传导是由直接面对BG膜的突触前元件异位释放递质介导的。
