Murphy T H, Blatter L A, Wier W G, Baraban J M
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
J Neurosci. 1993 Jun;13(6):2672-9. doi: 10.1523/JNEUROSCI.13-06-02672.1993.
The identification of neurotransmitter receptors and voltage-sensitive ion channels on astrocytes (reviewed by Barres, 1991) has renewed interest in how these cells respond to neuronal activity. To investigate the physiology of neuron astrocyte signaling, we have employed primary cortical cultures that contain both neuronal and glial cells. As the neurons in these cultures exhibit synchronous spontaneous synaptic activity, we have used both calcium imaging and whole-cell recording techniques to identify physiological activity in astrocytes related to neuronal activity. Whole-cell voltage-clamp records from astrocytes revealed rapid inward currents that coincide with bursts of electrical activity in neighboring neurons. Calcium imaging studies demonstrate that these currents in astrocytes are not always associated with slowly propagating calcium waves. Inclusion of the dye Lucifer yellow within patch pipettes confirmed that astrocytes are extensively coupled to each other but not to adjacent neurons, indicating that the currents observed are not due to gap junction connections between these cell types. These currents do not reflect widespread diffusion of glutamate or potassium released during neuronal activity since a population of small, round, multipolar presumed glial cells that are not dye coupled to adjacent cells did not display electrical currents coincident with neuronal firing, even though they respond to locally applied glutamate and potassium. These findings indicate that, in addition to the relatively slow signaling conveyed by calcium waves, astrocytes also display rapid electrical responses to neuronal activity.
星形胶质细胞上神经递质受体和电压敏感性离子通道的鉴定（Barres于1991年进行了综述），重新引发了人们对这些细胞如何响应神经元活动的兴趣。为了研究神经元-星形胶质细胞信号传导的生理学，我们采用了包含神经元和神经胶质细胞的原代皮质培养物。由于这些培养物中的神经元表现出同步的自发突触活动，我们使用钙成像和全细胞记录技术来识别星形胶质细胞中与神经元活动相关的生理活动。来自星形胶质细胞的全细胞电压钳记录显示，快速内向电流与相邻神经元的电活动爆发同时出现。钙成像研究表明，星形胶质细胞中的这些电流并不总是与缓慢传播的钙波相关。在膜片吸管中加入染料荧光黄证实，星形胶质细胞彼此广泛耦联，但不与相邻神经元耦联，这表明观察到的电流不是由于这些细胞类型之间的缝隙连接。这些电流并不反映神经元活动期间释放的谷氨酸或钾的广泛扩散，因为一群小的、圆形的、多极的假定神经胶质细胞，它们与相邻细胞没有染料耦联，即使它们对局部施加的谷氨酸和钾有反应，也没有显示出与神经元放电同时出现的电流。这些发现表明，除了钙波传递的相对缓慢的信号外，星形胶质细胞对神经元活动也表现出快速的电反应。
