Fig. 1.

a Treatment of NPCs with old rat serum (ORS, N = 5) reduces relative cell proliferation as measured by mitochondrial MTT when compared with young rat serum (YRS, N = 5), whereas the serum from old rats treated with NT-020 (ORS-NT, N = 5) is significantly higher than that found with old rat serum (one-way ANOVA F(2,12) = 65.45 followed by Sidak’s multiple comparison test *p < 0.05; **p < 0.001). A similar effect is observed in (b) when examining BrdU-positive cells after 48-h treatment with 10 % serum. There is a significant negative effect of old rat serum on the number of BrdU-positive cells, and this is increased in NPCs treated with serum from old rats fed NT-020 (one-way ANOVA F(2,17) = 13.64, followed by Sidak’s multiple comparison test ***p < 0.001; *p < 0.05)