Figure 5. The reactive gliosis in astrocyte and microglia in the acute phase of ischemic injury following HI is attenuated by pretreatment with Ginseng or DMF in an Nrf2-dependent manner.

Representative images of GFAP positive astrocyte (A, scare bar: 100 μm) and Iba1 positive microglia (B, scare bar: 50 μm) in the ipsilateral cortex and striatum of mice at 24 h after HI; and open squares in top left image indicate the peri-infarct areas of striatum and cortex used for micrographic examination. (B and C) Quantifications of the total number of GFAP positive cells of A. (E and F) Quantifications of Iba1 signals area of B. In both genotypes (A, C and D), acute ischemic insult evoked astrocytic activation and proliferation, indicated by the increased number of reactive astrocytes with hypertrophic somas and highly stained processes. Apparently, much less degenerated reactive astrocytes with breakdown cell bodies were detected in Ginseng- or DMF- pretreated ischemic WT, but not Nrf2^−/−, mice compared to corresponding controls. Meanwhile, pretreatment with Ginseng or DMF significantly protected against the decline in the total number of GFAP positive cells in WT mice, but not Nrf2^−/− mice. In contrast, Nrf2 deficiency exacerbated the decline of reactive astrocytes compared to WT controls. In both WT and Nrf2^−/− mice (B, E and F), acute ischemic insult triggered significant activation of microglia characterized by hypertrophic soma with thickened and retracted processes, while, interestingly, the Iba1 expression level displayed a tendency of decline in Nrf2^−/− mice compared to WT controls. Pretreatment with Ginseng or DMF significantly reduced the Iba1positive signals in WT mice, but not Nrf2^−/− mice. These results support that the pretreatment with Ginseng or DMF attenuated the deteriorative progression of reactive gliosis in astrocytes and microglia in an Nrf2-dependent fashion. n = 4–6 per group. *P < 0.05, ^**P < 0.01, #P < 0.05.