Gap junction-mediated astrocytic networks in the mouse barrel cortex
Gap junction-mediated astrocytic networks in the mouse barrel cortex
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DOI：
10.1523/jneurosci.5100-07.2008
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发表时间：
2008-05-14
影响因子：
5.3
通讯作者：
Giaume, Christian
中科院分区：
文献类型：
--
作者：
Houades, Vanessa;Koulakoff, Annette;Giaume, Christian
躯体感觉皮层的桶场构成了神经元和星形胶质细胞之间的解剖功能区室化和活动依赖性相互作用的一个有据可查的例子。在星形胶质细胞中，通过由连接蛋白43和30组成的间隙连接通道的细胞间通讯是网络组织的基础。免疫组织化学和电生理实验进行了研究，以确定在第四层的发展桶皮质星形胶质细胞网络的耦合特性。这两个连接蛋白的表达被认为是丰富的桶相比，隔膜和其他皮质层。用生物胞素进行的染料偶联实验和用特定细胞标记物进行的免疫染色的组合证明星形胶质细胞网络不涉及神经元、少突胶质细胞或NG2细胞。染料耦合的形状是椭圆形的桶皮质，而它是圆形的IV层以外的桶领域。这些耦合区域的二维分析表明，间隙连接通信限制从桶到它的邻居。在缺乏桶组织的转基因小鼠中没有观察到这种连接蛋白表达和横向限制的富集，而在具有恢复桶的双转基因小鼠中观察到它们。磺酰罗丹明B扩散的直接观察表明，位于两个桶之间的星形胶质细胞是弱耦合或不耦合，而桶内的耦合朝向其中心。这些观察结果表明，由于星形胶质细胞亚群具有不同的耦合特性，有助于塑造星形胶质细胞网络的桶内耦合的优先取向。这些特性限制了星形胶质细胞内的细胞间通信，如先前报道的兴奋性神经元回路。
The barrel field of the somatosensory cortex constitutes a well documented example of anatomofunctional compartmentalization and activity-dependent interaction between neurons and astrocytes. In astrocytes, intercellular communication through gap junction channels composed by connexin 43 and 30 underlies a network organization. Immunohistochemical and electrophysiological experiments were undertaken to determine the coupling properties of astrocyte networks in layer IV of the developing barrel cortex. The expression of both connexins was found to be enriched within barrels compared with septa and other cortical layers. Combination of dye-coupling experiments performed with biocytin and immunostaining with specific cell markers demonstrated that astrocytic networks do not involve neurons, oligodendrocytes or NG2 cells. The shape of dye coupling was oval in the barrel cortex whereas it was circular in layer IV outside the barrel field. Two-dimensional analysis of these coupling areas indicated that gap junctional communication was restricted from a barrel to its neighbor. Such enrichment of connexin expression and transversal restriction were not observed in a transgenic mouse lacking the barrel organization, whereas they were both observed in a double-transgenic mouse with restored barrels. Direct observation of sulforhodamine B spread indicated that astrocytes located between two barrels were either weakly or not coupled, whereas coupling within a barrel was oriented toward its center. These observations indicated a preferential orientation of coupling inside the barrels resulting from subpopulations of astrocytes with different coupling properties that contribute to shaping astrocytic networks. Such properties confine intercellular communication in astrocytes within a defined barrel as previously reported for excitatory neuronal circuits.