Hirase Research Unit, RIKEN Brain Science Institute, Wako, Japan. mail:
J Neurosci. 2010 Feb 24;30(8):3093-100. doi: 10.1523/JNEUROSCI.5065-09.2010.
Previous anatomical and in vitro electrophysiology studies suggest that astrocytes are heterogeneous in physiology, morphology, and biochemical content. However, the extent to which this diversity applies to in vivo conditions is largely unknown. To characterize and classify the physiological and morphological properties of cerebral cortical and hippocampal astrocytes in the intact brain, we performed in vivo intracellular recordings from single astrocytes using anesthetized mature rats. Astrocytes were classified based on their glial fibrillary acidic protein (GFAP) immunoreactivity and cell body locations. We analyzed morphometric measures such as the occupied volume and polarity, as well as physiological characteristics such as the mean membrane potential. These measurements did not show obvious segregation into subpopulations, suggesting that gray matter astrocytes in the cortex and hippocampus are composed of a homogeneous population in mature animals. The membrane potential of astrocytes in both cortex and hippocampus fluctuated within a few millivolts in the presence of spontaneous network activity. These membrane potential fluctuations of an astrocyte showed a significant variability that depended on the local field potential state and cell body location. We attribute the variability of the membrane potential fluctuations to local potassium concentration changes due to neuronal activity.
先前的解剖学和体外电生理学研究表明，星形胶质细胞在生理学、形态学和生化内容上存在异质性。然而，这种多样性在多大程度上适用于体内条件还很大程度上未知。为了描述和分类完整大脑中海马和大脑皮层星形胶质细胞的生理和形态特性，我们使用麻醉成熟大鼠进行了单个星形胶质细胞的体内细胞内记录。根据胶质纤维酸性蛋白（GFAP）免疫反应和细胞体位置对星形胶质细胞进行分类。我们分析了形态计量学指标，如占据体积和极性，以及生理特性，如平均膜电位。这些测量结果并未显示出明显的亚群分离，表明成熟动物的大脑皮层和海马中的灰质星形胶质细胞由同质群体组成。在存在自发网络活动的情况下，海马和大脑皮层中星形胶质细胞的膜电位在几毫伏内波动。星形胶质细胞膜电位的波动具有显著的可变性，这取决于局部场电位状态和细胞体位置。我们将膜电位波动的可变性归因于神经元活动引起的局部钾浓度变化。
