Figure 3. Caloric restriction (CR) and β-hydroxybutyrate (HB) increases FoxO1 activation during aging. Western blot analyses for renal nuclear (A) FoxO1, FoxO3, and FoxO6 as well as (B) PGC-1α and p65 were performed on nuclear proteins from rats treated with Young, Old, HB, and CR. Western blot results from 3 independent experiments were quantified by densitometry. #p < 0.05, ##p < 0.01, ###p < 0.001 vs. Young; *p < 0.05, **p < 0.01, ***p < 0.001 vs. Old. (C) Nuclear extracts were prepared from kidneys from young and aged rat. Immunoprecipitation assay showed PGC-1α was physically associated with p-serine, p-FoxO1, FoxO1, p-p65, and p65.