Age-related differences in dietary regulation of lipogenic enzymes in rat liver.

The activity of lipogenic enzymes in rat liver decreases during fasting and is increased on subsequent refeeding. There are considerable age-related differences in the activities of the lipogenic enzymes on dietary manipulation. On refeeding starved animals with either a standard diet or with a high-sucrose, fat-free diet, the increase of the activities was much greater in young animals than in old ones. Old animals exhibited a hyperlipoproteinemia and the activities of their lipogenic enzymes were decreased. The present results, together with reports in the literature, make it likely that the diminished activity of lipogenesis in old animals is a function of adipositas rather than of age.