Zahs K R, Newman E A
Department of Physiology, University of Minnesota, School of Medicine, Minneapolis 55455, USA.
Glia. 1997 May;20(1):10-22.
Gap junctional communication between glial cells is thought to play a role in K+ spatial buffering, in the propagation of inter-astrocytic Ca2+ waves, and in glial-neuronal signaling. In the present study, we characterize dye coupling between astrocytes, and between astrocytes and Müller cells, in the isolated rat retina. Whole-cell patch recordings were obtained from retinal astrocytes and Müller cells and the cells filled with Lucifer Yellow and neurobiotin. Spread of Lucifer Yellow to two to ten neighboring astrocytes occurred in 90% of the astrocyte recordings. After fixation and incubation of the retina with fluorescent conjugated streptavidin, neurobiotin was seen to label clusters of 13-88 astrocytes, as well as > 100 Müller cells. In contrast, when Müller cells were filled with Lucifer Yellow and neurobiotin, both tracers were confined solely to the recorded Müller cell. The uncoupling agents octanol, halothane, and doxyl-stearic acid were tested for their ability to uncouple retinal glia in situ. All three agents eliminated the visible spread of Lucifer Yellow from the injected astrocyte and the spread of neurobiotin into Müller cells. However, only doxyl-stearic acid combined with octanol eliminated the spread of neurobiotin between astrocytes. These results demonstrate that astrocytes in the rat retina are coupled to each other and to Müller cells. The astrocyte-to-Müller cell coupling is asymmetric, allowing transfer of the tracer in the forward direction only. In addition, astrocyte-to-Müller cell coupling is more sensitive to the uncoupling agents tested than is astrocyte-to-astrocyte coupling.
胶质细胞间的缝隙连接通讯被认为在钾离子空间缓冲、星形胶质细胞间钙离子波的传播以及胶质-神经元信号传导中发挥作用。在本研究中，我们对分离的大鼠视网膜中星形胶质细胞之间以及星形胶质细胞与穆勒细胞之间的染料偶联进行了表征。从视网膜星形胶质细胞和穆勒细胞获得全细胞膜片钳记录，并将细胞用荧光素黄和神经生物素填充。在90%的星形胶质细胞记录中，荧光素黄扩散到两到十个相邻的星形胶质细胞。在用荧光共轭链霉亲和素固定并孵育视网膜后，可见神经生物素标记了13 - 88个星形胶质细胞簇以及超过100个穆勒细胞。相反，当穆勒细胞用荧光素黄和神经生物素填充时，两种示踪剂都仅局限于所记录的穆勒细胞。测试了解偶联剂辛醇、氟烷和硬脂酸多昔醇原位解偶联视网膜神经胶质的能力。所有这三种试剂都消除了荧光素黄从注入的星形胶质细胞的可见扩散以及神经生物素向穆勒细胞的扩散。然而，只有硬脂酸多昔醇与辛醇联合使用才消除了神经生物素在星形胶质细胞之间的扩散。这些结果表明，大鼠视网膜中的星形胶质细胞彼此之间以及与穆勒细胞相互偶联。星形胶质细胞与穆勒细胞的偶联是不对称的，仅允许示踪剂向前传递。此外，与星形胶质细胞间的偶联相比，星形胶质细胞与穆勒细胞的偶联对所测试的解偶联剂更敏感。
