Hepatic Fasting-Induced PPARα Activity Does Not Depend on Essential Fatty Acids

The liver plays a central role in the regulation of fatty acid metabolism, which is highly sensitive to transcriptional responses to nutrients and hormones. Transcription factors involved in this process include nuclear hormone receptors. One such receptor, PPAR alpha, which is highly expressed in the liver and activated by a variety of fatty acids, is a critical regulator of hepatic fatty acid catabolism during fasting. The present study compared the influence of dietary fatty acids and fasting on hepatic PPAR alpha-dependent responses. Ppar alpha(-/-) male mice and their wild-type controls were fed diets containing different fatty acids for 10 weeks prior to being subjected to fasting or normal feeding. In line with the role of PPAR alpha in sensing dietary fatty acids, changes in chronic dietary fat consumption influenced liver damage during fasting. The changes were particularly marked in mice fed diets lacking essential fatty acids. However, fasting, rather than specific dietary fatty acids, induced acute PPAR alpha activity in the liver. Taken together, the data imply that the potent signalling involved in triggering PPAR alpha activity during fasting does not rely on essential fatty acid-derived ligand.