Figure 3.

Role of reactive oxygen species in microglial activation. A, Superoxide formation in microglia is detected by oxidized DHE fluorescence, and microglial morphology is shown in the corresponding phase contrast images. ZnCl₂ induces superoxide formation during microglial activation. Apocynin (500 μm) blocks both of these effects, whereas PJ-34 (400 nm) blocks microglial activation without blocking superoxide formation. Images are representative of four independent studies performed in triplicate. Scale bar, 40 μm. B, Zinc-induced microglial activation is blocked by PJ-34, and by the ROS scavenger Trolox (100 μm), but not by superoxide dismutase (SOD) plus catalase (each 200 U/ml). Exogenous delivery of 50 μm H₂O₂ to the medium also induces microglial activation that is blocked by PJ-34 or Trolox. n = 3; *p < 0.01 versus ZnCl₂ or H₂O₂ alone; ^†p < 0.01 versus control. C, p47^phox−/− microglia assume the activated morphology when exposed to H₂O₂. *p < 0.05 versus control; n = 3. Error bars indicate SEM.