Figure 7

Microglia reduce caspase activation in oligodendrocytes. Fragmented and condensed nuclei in oligodendrocyte cultures (A) were found in all cell bodies that labeled with a caspase indicator probe (B), which allowed for identification of oligodendrocytes by morphology. Overlap of apoptotic-morphology nuclei and the caspase indicator were used to confirm apoptotic cell death (C). The inset in panel C shows another representative image of a fragmented nucleus in an oligodendrocyte positive for caspase activation. Cell counts were conducted to quantify caspase activation (D, * = p < 0.05, factorial ANOVA for main effect of microglia, error bars = SEM). Microglia and LPS-activated microglia both reduced oligodendrocyte apoptosis, suggesting that increased oligodendrocyte survival in the presence of microglia is due to a reduction in apoptosis. As in figure 5, the protective effect of microglia was unchanged by the presence of LPS (factorial ANOVA).