HIF1a serves as a protective factor to prevent brain damage. (A-C) IHC on brain sections from WT, cKO P2, and cKO P2/H1 for Iba1 (brown) showing more activated microglia cells in brain sections of a cKO P2/H1 mouse. (D-F) IHC on brain sections from a freshly deceased cKO P2/H1 mouse for (D) cleaved-caspase3 (cl-Casp3; red), (E) neurons (NeuN; green), and (F) a merged picture combined with DAPI (white arrows depict typical examples of cl-Casp3⁺ neurons). No obvious cl-Casp3 staining was detected in WT or cKO P2 brains (data not shown). (G) Expression profile (qRT-PCR) of different genes in the lysate of the entire brain of cKO P2 and cKO P2/H1 mice in relation to their respective WT littermates (n = 5-9). All data are mean ± SEM (*P < .05). Scale bars in panels A through C, 100 μm; panels D through F, 50 μm.