Anesthetized mice were imaged through a thin-skull preparation.
(a) Overlay of microglia at t=0 (magenta) and t=30 (green) in
mice treated with saline (S) or nadolol/clenbuterol (NC); note increased
retraction of processes (magenta) in NC mice. (b) Microglia in mice
treated with NC, but not S or nadolol only (N) have a rapid transient increase
in the retraction ratio (retracted pseudopodia/total pseudopodia) from
0–30min (n: S=6, N=5, NC=6 mice, two-way RM-ANOVA, significant main
effects of treatment (p=0.00084, F(2,13)=12.82) and time (p=0.0018,
F(1,13)=15.27), and interaction (p=0.0026, F(2,13)=9.72). Holm-Sidak multiple
comparisons, S v. NC, p=0.00011). (c) Example microglia from S and
NC treated mice. (d) Sholl profile of S-, N-, and NC-treated mice;
note the reduction in microglial arborization in NC-treated mice (n: S=7, N=8,
NC=6 mice, 3–5 microglia per animal). (e) NC reduces Sholl
area under the curve (AUC) (n: S=7, N=8, NC=6 mice, one-way ANOVA, p=0.00040,
F(2,18)=12.45, Holm-Sidak multiple comparisons: S v. NC p=0.00036, N v. NC
p=0.0045). (f) Maximum number of Sholl intersections is reduced in
NC-treated microglia (n: S=7, N=8, NC=6 mice, one-way ANOVA, p=0.00019,
F(2,18)=14.31, Holm-Sidak multiple comparisons: S v. NC p=0.00025, N v. NC
p=0.00091). (g) Initial ramification (t=0) and 2D max-projections
(t=0–60) of microglial process surveillance in S- and NC-treated mice;
note decreased surveillance in the NC-treated mice. (h) Microglia
in NC- and DSP4-treated mice survey less of the parenchyma (n: S=16, N=8, NC=12,
DSP4=12, ICI=11 mice, one-way ANOVA, p=2.6×10−7,
F(4,55)=12.51, Holm-Sidak multiple comparisons tests: S v. NC
p=6.6×10−6, S v. DSP4 p=0.013, N v. ICI p=0.034, NC
v. ICI p=1.1×10−6, DSP4 v. ICI p=0.0015). Scale bars =
20μm. Graphs show mean±SEM. Abbreviations: S=saline, N=nadolol,
NC=nadolol/clenbuterol, DSP4=N-(2-Chloroethyl)-N-ethyl-2-bromobenzylamine,
ICI=ICI-118,551; *p<0.05, **p<0.01, ***p<0.005,
****p<0.0001). Points represent individual animals. See Supplementary Table 1 for the
number of females and males used in these experiments.