Different sensitivity of PPARa gene expression to nutritional changes in liver of suckling and adult rats.

Abstract

The amount of peroxisome proliferator-activated receptor-ex (PPARcx) protein was markedly augmented in the liver of suckling rats compared to adult rats. This different PPARcx abundance was used to study the sensitivity to nutritional changes in the expression and activity of this receptor. Thus, 10-day-old and adult rats were orally given either glucose, Intralipid or a combination of both diets, and liver mRNA levels of PPARcx and the PPAR related genes, acyl-CoA oxidase (ACO) and phosphoenolpyruvate carboxykinase (PEPCK), and plasma metabolites were measured. In neonates, the expression of PPARcx and ACO was seen to increase when the level of FF A in plasma was also high, unless an elevated level of insulin was also present. However, this fatty acid-induced effect was not detected in adult rats. On the contrary, the hepatic expression of PEPCK was modulated by the nutritional changes similarly in both neonates and adult rats. Thus, it may be concluded that the expression of the PPARcx gene in adult rats seems to be less sensitive to nutritional changes than in neonates.