Figure 5.

Long-term changes in Nrg1 levels in the hippocampus in response to neonatal HI. (A) Hippocampal Nrg1 levels decreased between P11 and P18 and reach a nadir prior to P40 (quadratic R² 0.72, p < 0.001). (B) HI increased hippocampal Nrg1 levels by 84.4% (p = 0.01) and 44.8% (p = 0.05) at P11 and P15 after the insult, respectively (KW p < 0.05; *, Dunn-Bonferroni post-hoc p < 0.05 vs. sham). After 120h, Nrg1 was similar in all three groups. (C) The 150 kDa α- fodrin breakdown product weakly correlated with Nrg1 (Spearman’s Rho r = 0.53, p = 0.004) in a cubic regression, which plateaued at a Nrg1 level of ~28.5 pg/gr of protein (C₁). Representative western blots demonstrating the breakdown of α- fodrin are shown at 120 and 150 kDa (C₂). (D) Stratification by sex, demonstrated that Nrg1 peaked early after neonatal HI in both male and female mice (KW p = 0.02 and KW p = 0.01, respectively), but sooner in female mice. (E) Higher Nrg1 (red) and lower PV (green) expression are shown in CA1 (E₁) and CA3 (E₂) pyramidal cell layer (Py) in the dorsal hippocampus of HI-injured mice compared to sham by IF-IHC and confocal microscopy. Scale bar = 200 µm. Quantifications are shown as hybrid box & whisker and vertical dot plots. *, p < 0.05 (Dunn-Bonferroni post-hoc test for Kruskal Wallis ANOVA; n shown under each box).