Fig. 3

Iron deposition causes neuronal degeneration. Age- and weight-matched WT, HO2^−/−, and Hpx^−/− male mice were injected with 10 μL of SFHb, and brains were sectioned and stained with Fluoro-Jade B and Perls’ iron staining 24 h after injection, respectively. Under microscopy, the positive signals of Fluoro-Jade B and Perls’ iron staining were colocalized partially on continuous neighbor sections. The inset image shows that glia-like cells (arrow head) were activated around the lesion area (star). Scale bar, 200 μm (a). Quantitative data demonstrated that HO2^−/− mice have a larger Perls’ iron-positive area compared to WT controls after injection (b). Representative images were shown of the Perls’ iron staining (blue) with various cellular markers (brown): Iba1 for microglial cells, GFAP for astrocytes, and NeuN for neurons, which illustrated that the Perls’ iron-positive signals were mainly in microglial cells. Scale bar, 50 μm (c). The degenerating neurons and Perls’ iron-positive cells are shown in coronal sections. Scale bar, 50 μm (d). The 10-μL SFHb injection produced significantly more degenerating neurons (e) and Perls’ iron-positive microglial cells (f) in HO2^−/− and Hpx^−/− mice than those in WT controls. Values represent means ± SEM. *P < 0.05, **P < 0.01, and ***P < 0.001, compared to WT mice, one-way ANOVA followed by Newman-Keuls multiple comparison tests (n = 5–6)