Age-related response to dietary fructose in the rat: discrepancy in triglyceride and apolipoprotein B synthesis as a possible mechanism for fatty liver induction in adult rats.

The effects of fructose feeding on plasma and liver lipids, triglyceride secretion, and plasma apolipoprotein B and their liver mRNA level were studied in young and adult rats. We have shown that the responsiveness of adult rats to dietary fructose differs from that of young rats with regard to body parameters as well biochemical analyses. In young rats, fructose diet causes a coupled induction of liver triglyceride and apolipoprotein B synthesis via increased mRNA level. In adult rats it appears that triglyceride secretion is lower and less inducible by dietary fructose than in young rats. This insufficient export of the excess of synthesized triglycerides may cause fatty liver in adult animals. Reduced adaptation of liver lipoprotein secretion to dietary carbohydrates in adult animals may be explained by the failure to stimulate apolipoprotein B synthesis at the mRNA level in these rats.