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. Author manuscript; available in PMC: 2015 Apr 16.
Published in final edited form as: Neuron. 2014 Apr 16;82(2):380–397. doi: 10.1016/j.neuron.2014.02.040

Figure 1. CSF1R inhibition eliminates microglia from the adult brain.

Figure 1

12 month-old wild-type mice (C57BL/6/129 mix; n = 4–5 per group) were treated with PLX3397 (290 mg/kg chow) for 0, 1, 3, 7, 14, or 21 days. A–F) Immunostaining for IBA1 shows robust decreases in microglial numbers, with no detectable microglia present after 21 days of treatment. G–I) IBA1 immunostaining shows changes in microglia morphology during treatment, with representative microglia shown from control, 7-, and 21- days treated mice, imaged from between the blades of the dentate gyrus. J–N) Representative IBA1 immunofluorescent staining from the hippocampal region showing 63XZ-stacks of microglia during treatment. Scale bar represents 20 μM. O) Quantification of number of IBA1+ cell bodies from a 10X field of view from the hippocampal regions as a function of time. Statistical analyses were performed via one-way ANOVA indicating p <0.0001 for CA1, CA3, and subiculum, comparing all timepoints, shown as an average for all 3 regions. P, Q) IBA1+ cell debris and non-intact cell parts were observed throughout the brains of mice treated with CSF1R inhibitors. Arrows indicate these microglial remnants alongside intact microglia. R–S) 2 month-old CX3CR1-GFP+/− mice were treated with PLX3397 or vehicle for 3 days (n = 3 per group). Brains were sectioned and the number of GFP+ cell bodies counted from a 10X field of view of the hippocampus, cortex, and thalamus. Each white dot represents a GFP+ cell body. T) 2 month-old CX3CR1-GFP+/− mice were treated with PLX3397 for 7 days or vehicle (n = 3 per group). Brains were then extracted, dissociated into a single cell suspension, and then incubated with PI. Flow cytometry was then performed revealing >90% reduction in the number of GFP+ cells with treatment compared to vehicle treated. U) The fraction of GFP+ cells that were undergoing cell death, as shown by incorporation of PI, was significantly higher with PLX3397 treatment than vehicle, consistent with microglial cell death with CSF1R inhibition. V) Total brain volumes were measured via Cavalieri stereology in 2 month-old wild-type mice treated with PLX3397 or vehicle for 7 days (n = 4 per group). No significant differences were seen. * indicates significance (p <0.05) by unpaired students T-test. Erorr bars indicate SEM. CA, cornusammonis; DG, dentate gyrus; O, stratum oriens; R, stratum; M, molecular layer dentate gyrus; H, hilus.