Fig. 1

Reduced cortical CBF and vascular density in ApoE4-TR mice. a Neocortical CBF, assessed by ASL-MRI, is lower in ApoE4-TR mice, compared to WT and ApoE3 mice. Scale bar = 1 mm. b. RBC speed in neocortical vessels (depth = 200 µm) in ApoE3-TR and ApoE4-TR mice assessed by 2-photon microscopy after injection of FITC-labeled dextran to label the vasculature. Top two images show the microvasculature in ApoE3 and ApoE4 mice. The colored rectangles indicate the location of the vessels (arterioles, capillaries, and venules) in which line scans were obtained to determine RBC speed (right panels). The bottom graph shows the RBC speed measured by line scans as function of the vessel diameter: arterioles (>10 µm) to the left, capillaries in the middle (≤10 µm; placed on arteriole or venule side depending on whether they were topologically closer to an arteriole or venule) and venules (>10 µm) to the right (ApoE3 n = 166 vessels in four mice, ApoE4 n = 197 vessels in four mice). Scale bars are 100 µm, 50 µm, 100 ms, respectively, for the large, small, and line scan images. c CD31⁺ microvessels are reduced in ApoE4 mice both in neocortex and CC. Scale bar = 250 µm. The ApoE3-TR mice did not differ from WT mice (p > 0.05). Data are expressed as means ± SEM. N = 5/group in a and c; *p < 0.05; one-way ANOVA and Tukey’s test