Figure 4

Axonal pathology in the corpus callosum is significantly reduced by erythropoietin (EPO) after traumatic axonal injury with hypoxia (TAI + Hx). Representative photomicrographs from the corpus callosum demonstrating axonal bulbs (black arrows) and swollen axons (white arrows) using the NF-200 marker at 1 d following sham (A), TAI (B), or TAI + Hx (D) surgery. (C) When treated with EPO, TAI rats did not have any reduction in axonal pathology, however TAI + Hx rats (E) were afforded remarkable reduction of axonal bulbs when treated with EPO. Scale bar = 100 μm. (F) Number of axonal bulbs in the corpus callosum of TAI rats 1, 7 and 14 d postinjury with vehicle or EPO treatment. No benefit of EPO was observed in after TAI. (G) Number of swollen axons in the corpus callosum of TAI rats 1,7 and 14 d postinjury with either vehicle or EPO treatment. Again, no differences were observed in swollen axons between TAI or TAI + Hx at any time point. (H) Number of axonal bulbs counted in the corpus callosum after TAI + Hx with/without EPO treatment at 1, 7 and 14 d, demonstrating a significant beneficial effect of EPO at 1 and 7 d (*P <0.05; 2-way ANOVA with post-hoc Bonferroni test). (I) Although there was a decrease in the number of swollen axons in the corpus callosum of rats allocated to TAI + Hx or TAI + Hx + EPO treatment at 1, 7 or 14 d, this was not statistically significant. Data shown as mean ± SEM, n = 6 per group per time point.