ABSTRACT
This chapter summarizes findings in the transcriptional regulation of carbohydrate and lipidmetabolism in liver, and aims to place them in physiological contexts. Transcriptional regulation plays the major role in metabolic adaptation process. The receptor PPARa plays an essential role in the metabolic adaptation to fasting by inducing genes for fatty acid oxidation and ketogenesis. Liver plays a central role in the regulation of macronutrient metabolism in response to changes in physiological and dietary conditions. Classic work in biochemistry has elucidated acute regulation of enzyme activities involved in glucose metabolism by phosphorylation dephosphorylation and by allosteric action of intermediate metabolites. Insulin and glucocorticoids synergistically induce lipogenic enzymes in liver. Liver plays a critical role in energy metabolism during fasting by providing glucose and ketone bodies to other organs. The physiological role of glucocorticoids in energy metabolism is both the adaptation to fasting and the replenishing of energy stores upon refeeding.
