Asymmetric gap junctional coupling between glial cells in the rat retina

✍ Scribed by Kathleen R. Zahs; Eric A. Newman

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 494 KB
• Volume: 20
• Category: Article
• ISSN: 0894-1491
• DOI: 10.1002/(sici)1098-1136(199705)20:1<10::aid-glia2>3.0.co;2-9

✦ Synopsis

Gap junctional communication between glial cells is thought to play a role in K 1 spatial buffering, in the propagation of inter-astrocytic Ca 21 waves, and in glial-neuronal signaling. In the present study, we characterize dye coupling between astrocytes, and between astrocytes and Mu ¨ller cells, in the isolated rat retina.

Whole-cell patch recordings were obtained from retinal astrocytes and Mu ¨ller 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 Mu ¨ller cells. In contrast, when Mu ¨ller cells were filled with Lucifer Yellow and neurobiotin, both tracers were confined solely to the recorded Mu ¨ller 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 Mu ¨ller 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 Mu ¨ller cells. The astrocyte-to-Mu ¨ller cell coupling is asymmetric, allowing transfer of the tracer in the forward direction only. In addition, astrocyte-to-Mu ¨ller cell coupling is more sensitive to the uncoupling agents tested than is astrocyte-to-astrocyte coupling.