DECREASE IN HEPATIC LIPOGENESIS IN TERM RAT LIVER EXPLANTS

Abstract

Hepatic lipogenesis in the fetal rat is highly active until the time of birth when it decreases and remains low throughout the suckling period. High fat intake during suckling is thought to suppress hepatic lipogenesis. By utilizing explants of fetal rat liver we have demonstrated that the decrease in hepatic fatty acid synthesis may occur independent of nutritional influences. Explants obtained from fetal rats at 17 and 22 days gestation were incubated for 48 hours in F12 medium without added hormones or serum. Incorporation of acetate-1-14C into long chain fatty acids during a 6 hour pulse was determined at 0 time and after 48 hours in culture and is shown below. Data are expressed as % incorporation/mg protein/6 hours. Production of 14CO2 from uniformly labeled glucose was examined as an index of viability. There was no significant decrease in glucose oxidation in explants from either 17 or 22 day gestation fetuses during the 48 hours in culture. The results indicate that acetate incorporation into fatty acids in liver explants from 17 day fetuses remained constant between 0 and 48 hours in culture. Explants from 22 day fetuses, however, showed a striking decline in acetate incorporation. These data suggest that the decline in hepatic lipogenesis in the newborn rat may be independent of dietary influences.