Figure 4.

Treatment with INF-γ plus LPS or TNF-α enhances dye coupling between microglia from normal mice (open bars), but not between microglia of Cx43^del/del mice (filled bars). Cultures were incubated for 9 h under control conditions or with 1 ng/ml INF-α alone, 1 μg/ml LPS alone, 1 ng/ml TNF-α alone, 1 ng/ml INF-α plus 1 μg/ml LPS, or 1 ng/ml INF-γ plus 1 ng/ml TNF-α. There was little coupling under control conditions (C) or in cultures treated with one of the agents, but the two combined treatments resulted in a much higher incidence of dye coupling in cultures from wild-type mice. No cytokine treatment induced dye coupling of microglia from Cx43^del/del mice. Each point represents the mean ± SD of three independent experiments in which at least 10 cells were microinjected with Lucifer yellow.