Jabs Ronald, Pivneva Tatjana, Hüttmann Kerstin, Wyczynski Alexandra, Nolte Christiane, Kettenmann Helmut, Steinhäuser Christian
Experimental Neurobiology, Department of Neurosurgery, University of Bonn, Sigmund-Freud-Str. 25, 53105 Bonn, Germany.
J Cell Sci. 2005 Aug 15;118(Pt 16):3791-803. doi: 10.1242/jcs.02515. Epub 2005 Aug 2.
Glial cells increasingly gain importance as part of the brain's communication network. Using transgenic mice expressing green fluorescent protein (EGFP) under the control of the human GFAP promoter, we tested for synaptic input to identified glial cells in the hippocampus. Electron microscopic inspection identified synapse-like structures with EGFP-positive postsynaptic compartments. Sub-threshold stimulation to Schaffer collaterals resulted in stimulus-correlated, postsynaptic responses in a subpopulation of EGFP-positive cells studied with the patch-clamp technique in acute slices. This cell population can be recognized by its distinct morphology and has been termed GluR cells in a preceding study. These cells are distinct from the classical astrocytes due to their antigen profile and functional properties, but also lack characteristic features of oligodendrocytes or neurons. GluR cells also received spontaneous synaptic input. Stimulus-correlated and spontaneous responses were quantitatively analysed by ascertaining amplitude distributions, failure rates, kinetics as well as pharmacological properties. The data demonstrate that GABAergic and glutamatergic neurons directly synapse onto GluR cells and suggest a low number of neuronal release sites. These data demonstrate that a distinct type of glial cells is integrated into the synaptic circuit of the hippocampus, extending the finding that synapse-based brain information processing is not a property exclusive to neurons.
作为大脑通讯网络的一部分，神经胶质细胞的重要性日益凸显。我们利用在人类胶质纤维酸性蛋白（GFAP）启动子控制下表达绿色荧光蛋白（EGFP）的转基因小鼠，测试了海马体中已识别神经胶质细胞的突触输入。电子显微镜检查发现了具有EGFP阳性突触后区室的突触样结构。对沙氏侧支进行阈下刺激，在急性脑片中用膜片钳技术研究的一部分EGFP阳性细胞中引发了与刺激相关的突触后反应。这一细胞群体可通过其独特的形态识别，在前一项研究中被称为GluR细胞。这些细胞由于其抗原谱和功能特性，与经典星形胶质细胞不同，但也缺乏少突胶质细胞或神经元的特征性特征。GluR细胞也接受自发突触输入。通过确定幅度分布、失败率、动力学以及药理学特性，对与刺激相关的和自发的反应进行了定量分析。数据表明，γ-氨基丁酸能和谷氨酸能神经元直接与GluR细胞形成突触，并表明神经元释放位点数量较少。这些数据表明，一种独特类型的神经胶质细胞被整合到海马体的突触回路中，扩展了基于突触的大脑信息处理并非神经元独有的特性这一发现。
