Cultured astrocytes form a syncytium after maturation.
The formation of functional gap junctions between astrocytes was investigated during differentiation of these cells in culture. Precursor cells of GFA (glial fibrillary acidic) protein-positive astrocytes were cultured in a chemically defined medium as a homogeneous population. These cells were rarely coupled to one neighbour, as revealed by electrical and dye coupling and never formed a large syncytium, as investigated by injection and spread of Lucifer Yellow. Differentiation with respect to GFA protein accumulation can be induced in these cells by culturing in horse serum-containing medium. The formation of functional junctions developed within 2 weeks in about 20% of the cells. Coupled cells formed a large syncytium. When the astrocytes were co-cultured with primary cerebellar cells (consisting predominantly of small neurons) after the switch to serum-containing medium the percentage of coupled astrocytes increased to about 65%. Again the coupled cells formed a large syncytium. Since no physical contact was possible between the astrocyte cultures and the primary cerebellar cells the stimulation of coupling had to be signalized by soluble factor(s).
D000818:Animals; D001253:Astrocytes / Q000502:physiology*; D002454:Cell Differentiation; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D007546:Isoquinolines; D051379:Mice; D008810:Mice, Inbred C57BL
D005904:Glial Fibrillary Acidic Protein; D007546:Isoquinolines; C017475:lucifer yellow