Figure 2. Metformin restores brain vascular integrity of old mice. (A) Fold-change relative to the control group (n = 11) in cerebral blood flow (CBF) response to contralateral whisker stimulation was significantly increased in 10–12-month-old mice treated with metformin (n = 9). (B) Fold-change relative to the control group in CBF response to contralateral whisker stimulation was significantly increased in 20-month-old mice treated with metformin, and exhibited a dose-dependent tendency (number of mice in control group, n = 5; in 0.5mg/kg group, n = 6; in 5mg/kg group, n = 6; in 15mg/kg group, n = 5). (C) (left) 3D reconstruction of the hippocampus dentate gyrus and cortex zone vasculature generated by confocal imaging of 100 μm thick sections. (right) Quantification of blood vessel branchpoint per field in the hippocampus dentate gyrus and cortex of metformin, vascular endothelial growth factor (VEGF), and control groups (every treated group n ≥ 3). Scale bar = 100 μm. Ctrl: Control; Met: Metformin. The overall significance between two groups was determined by Student’s t-test, among three group was determined by one-way ANOVA. * p < 0.05, ** p < 0.01, *** p < 0.001, ns, not significant.