Figure 4. Longitudinal assessment of microglia activation in vivo by tracking changes in soma size.

(A) Quantification of soma size, IBA-1 and CD68 expression relative to control conditions 24 or 48 hours post LPS injection. Asterisks indicate significance for each condition compared to control (0 mg/kg LPS, 24 h), horizontal line represents statistical comparisons between indicated time points, n = 5, 6, 6, 6 and 6 animals/group, respectively. (B and C) Top: representative images of microglia (green) and blood vessels (red) imaged in vivo at indicated time points. Bottom: Outlines of segmented microglia from the corresponding image above color-coded to indicate soma size per cell under control (B) and LPS (2 mg/kg) (C) conditions; red corresponds to microglia with soma size >65 µm², thus activated. (D) Quantification of soma size measured in vivo as a function of time and LPS dose. Data from one control animal, and one LPS stimulated animal, are shown. Scale bar equals 50 µm.