Figure 3.

COX-1 expression in microglia and microglial activation by repeated social defeat. A, Double immunostaining for Iba-1, a marker for microglia, and COX-1 in the VTA of mice after repeated social defeat. COX-1 signals (red) were localized at Iba-1-positive microglia (green). Scale bar, 25 μm. B, Repeated defeat-induced increase in Iba-1 immunoreactivity in microglia in VTA. At 4 h after handling (control) or the last social defeat (defeat) at Day 10, brains were removed and subjected to immunofluorescent staining. Representative images of Iba-1 signals in VTA in the control and defeat conditions (left) and proportions of areas of Iba-1 immunoreactivity above the background in VTA (right) are shown. Note that Iba-1 signals in microglia were significantly enhanced after repeated social defeat, suggesting microglial activation. The number of mice is shown below each bar; *p < 0.05 for unpaired t test. Scale bars, 25 μm.