Figure 5: Targeted ablation of Sirt1 in OPCs abolishes HX-induced proliferation in white matter.

(a) Confocal images from Sirt1-WT and Sirt1-cKO mice after NX and HX. Cells were immunolabelled with anti-Sirt1, -GFP (to detect YFP) and -BrdU antibodies. Dotted lines delineate white matter (WM). Scale bar, 100 μm. (b,c) Graphs represent reduced proliferation in NX white matter of Sirt1-cKO mice compared with Sirt1-WT (b). HX increases percentages of BrdU⁺ and BrdU⁺YFP⁺ cells in Sirt1-WT mice, and decreases in Sirt1-cKO (b,c). Histograms show mean±s.e.m. Number of samples indicated in parentheses, 4 brains per condition and genotype. (d–f) Overexpression with pSirt1 plasmid in NX and HX white matter cells from Sirt1-WT and Sirt1-cKO (P18). Cells stained with anti-Sirt1, -BrdU antibodies and DAPI. Scale bar, 50 μm. (e,f) pSirt1 increased percentage of BrdU⁺ and NG2⁺ cells in NX cultures versus pHA controls. In Sirt1-cKO cultures, pSirt1 restored HX-induced BrdU⁺ and NG2⁺ cells. Histograms show mean±s.e.m. (three NX brains and four HX brains per genotype; four cultures per condition).