In addition to their defective fatty acid catabolism, Pparα−/− mice are hypoglycaemic and hypothermic during fasting.7 Because FGF21 is important for glucose homeostasis and for thermogenesis,13 we investigated the role of hepatocyte PPARα in controlling fasting glycaemia and body temperature. Both Pparαhep−/− and Pparα−/− mice were hypoglycaemic and hypothermic compared with WT mice during fasting. However, this phenotype was much stronger in fasted Pparα−/− mice compared with fasted Pparαhep−/− mice (figure 5H-J), indicating that extrahepatic PPARα strongly influenced whole-body glucose homeostasis and temperature independent of hepatocytic PPARα activity and FGF21 production.
