Figure 5. P7C3-S243 Blocks Cerebellar Axonal Degeneration and Preserves Balance and Coordination.

(A) Representative pictures from the cerebellar molecular layer show prominent silver staining of degenerating axons 12 days after blast-injury, in the absence of loss of NeuN or H&E staining. Images shown are representative of typical images from 5 animals in each group, and demonstrate that 3 and 30 mg/kg/day doses of P7C3-S243, initiated 24 hours after blast-injury, block axonal degeneration. Similar protective efficacy is seen in animals treated with 3 mg/kg/day of the highly active enantiomer (−)-P7C3-S243, but not in animals treated with the less active enantiomer (+)-P7C3-S243. (scale bar = 2.5µM). (B) Optical densitometry of light transmitted through silver-stained cerebellar molecular layer from all animals in each group was used to quantify the protective effect. The specific tissue area was manually delineated, and signal was quantified for 18 sections for each of the 5 animals, spaced 480 µM apart. A greater value indicates that more light passed unimpeded through the section by virtue of less silver staining, which reflects less axonal degeneration. (C) Seven days after blast-injury, mice show a trend towards impaired balance and coordination with increased foot slips that did not achieve statistical significance. By 28 days, however, blast-injured mice showed a two-fold increase in the number of foot slips relative to sham-injured mice. When daily oral treatment with 6 mg/kg/day of the active enantiomer (−)-P7C3-S243 was initiated 24 hours after blast-injury, however, mice performed normally in this task. Every group shown consisted of 25 male C57/Bl6 mice, aged 12–14 weeks, and data was collected and scored in an automated manner blind to treatment group. Significance was determined by 2 way ANOVA with Bonferroni post-hoc analysis. Data are represented as mean ± SEM. p-value labeled as **<0.01 and ****<0.0001 compared to blast-injured animals treated with vehicle. See also Figure S5, S6.