E. Niaspan does not ameliorate myelin thickness as indicated by g-ratio analysis, with axonal diameter distribution: WT 0.68 ± 0.003, 2945 fibers, n=5 animals; Pmp22-/- 0.64 ± 0.003, 1557 fibers, n= 6 animals; Pmp22-/- Niaspan 0.63 ± 0.003, 1445 fibers, n=6 animals, results are mean ± SEM. WT saline as compared to Pmp22-/- saline-treated p<0.0001; WT saline as compared to Pmp22-/- Niaspan-treated p<0.0001, repeated measures ANOVA. Note the loss of myelinated fibers in Pmp22-/- nerves for all caliber axons. 