NAC treatment shows little effect on oxysterol levels in Npc1−/− mice. (A) In liver, both 7-KC and 3β,5α,6β-cholestanetriol (3β,5α,6β-triol) levels showed statistically insignificant reductions following NAC treatment of Npc1−/− mice (unpaired t-test, P > 0.3; n = 11 for Npc1−/−, n = 9 for NAC-treated Npc1−/− mice). (B) In brain, the significantly higher level of 3β,5α,6β-triol of Npc1−/− mice relative to Npc1+/+ (P < 0.0001) was not reduced following NAC treatment (P = 0.12). (C) In brain, Npc1+/+ and Npc1−/− mice showed similar 7-KC levels (P = 0.3), and NAC treatment uniformly reduced 7-KC levels in both genotypes (P < 0.0001). For (B) and (C): n = 4–6 for each group; data analyzed by two-way ANOVA with Tukey's post-test; column lettering (a, b) indicates significance, as described in Figure 1. NAC-treated mice received 250 mg/kg NAC for 4 weeks, beginning at 4 weeks of age (P28). Means ± SD are shown.