Figure 1. RSD-induced anxiety-like behavior was paralleled by an increased percentage of circulating monocytes (CD11b+/SSClo/Ly6Chi) and macrophages (CD11b+/CD45hi) in the brain. Male C57BL/6 mice were subjected to one, three, or six cycles of social defeat (RSD) or left undisturbed as controls (CON). Anxiety-like behavior was determined 14 h after the final cycle of RSD (n = 6–9, 3 independent experiments). A, B, Time to enter the center of the open field (A) and total time spent in the open field (B). C, Time to enter the dark zone. D, Total time spent in the light zone. Following behavioral testing, blood and enriched brain CD11b+ cells were collected (n = 6–9, 3 independent experiments). E, Representative flow bivariate dot plots of SSC/CD11b and SSC/Ly6C labeling in the blood. Myeloid subsets were gated into Ly6C− monocyte (m: CD11b+/SSClo/Ly6C−), granulocyte (G: CD11b+/SSChi/Ly6Cint), and Ly6Chi monocyte (M: CD11b+/SSClo/Ly6Chi) subsets. F–H, The percentage of blood myeloid cells (F, CD11b+), granulocytes (G, G), and monocytes (H, m: Ly6C− or M: Ly6Chi). I, Representative flow bivariate dot plots of CD11b/CD45 labeling in Percoll-isolated microglia/macrophages and side scatter/forward scatter (SSC/FSC) properties are shown in RSD mice. J, The percentage of brain macrophages (CD11b+/CD45hi) are shown. Bars represent the mean ± SEM. Means with asterisk are significantly different from CON (p < 0.05) and means with number sign (#) tended to be different from CON (p < 0.06–0.10).