FGF21 is regulated by PPARα (ref. 25). Serum FGF21 was higher in P+A- mice than in P-A- and P-A+ mice (Fig. 4D). FGF21 may exert its effect via adiponectin (ref. 26–27). However, we did not see any significant difference in serum adiponectin between P-A- and P+A- mice (Fig. 4E). Instead, basal levels of serum C1q TNF Related Protein 3 (CTRP3), a new adipokine (ref.28), were upregulated in P-/A- mice and P-/A+ mice, and HFD feeding suppressed CTRP3 in P-/A- mice and P-/A+ mice but not in P+/A- mice, suggesting that PPARα contributes to maintaining the serum levels of CTRP3 stable in P+A- mice (Fig. 4F).
