Figure 5. E2 downregulates HIP expression in injured nerves.

(A) One week before surgical sciatic nerve-crush injury, E2 or saline (placebo) and PLGA was locally injected into the designated injury site, and the mRNA expression of HIP was evaluated from 3 hours to 7 days after injury; measurements were performed via qRT-PCR, normalized to endogenous 18S rRNA levels, and presented relative to the values obtained in the uninjured limb. (B) HIP mRNA expression was evaluated in mice treated with placebo, with E2 injections, or with injections of E2 and the E2-receptor blocker ICI; assessments were performed on day 3 after injury, when both Ptch1 and Gli1 mRNA expression were significantly upregulated (Figures 2C, D), via qRT-PCR, normalized to endogenous 18S rRNA levels, and presented relative to the values obtained in placebo-treated mice. (C) Sections from uninjured nerves were stained for co-expression of (top row) HIP (red) and the endothelial-cell marker CD31 (green), (second row) HIP (red) and the Schwann-cell marker S100 (green), (third row) Ptch1 (red) and CD31 (green), or (bottom row) Ptch1 (red) and S100 (green); nuclei were counterstained with DAPI (blue). (D) Sections from placebo- and E2-treated mice sacrificed 24 hours or 3 days after injury were stained for HIP expression (red); nuclei were counterstained with DAPI (blue). *P<0.01.