RESUMO
The overabundance of dietary fats and simple carbohydrates contributes significantly to obesity and metabolic disorders associated with obesity. The liver balances glucose and lipid distribution, and disruption of this balance plays a key role in these metabolic syndromes. We investigated (1) how hepatocytes balance glucose and fatty acid metabolism when one or both nutrients are supplied in abundance and (2) whether rat hepatoma cells (McA-RH7777) reflect nutrient partitioning in a similar manner as compared with primary hepatocytes. Increasing media palmitate concentration increased fatty acid uptake, triglyceride synthesis and beta-oxidation. However, hepatoma cells had a 2-fold higher fatty acid uptake and a 2-fold lower fatty acid oxidation as compared with primary hepatocytes. McA-RH7777 cells did not synthesize significant amounts of glycogen and preferentially metabolized the glucose into lipids or into oxidation. In primary hepatocytes, the glucose was mostly spared from oxidation and instead partitioned into both de novo glycogen and lipid synthesis. Overall, lipid production was rapidly induced in response to either glucose or fatty acid excess and this may be one of the earliest indicators of metabolic syndrome development associated with nutrient excess.
