Effect of maternal diet on fetal hepatic lipogenesis.

The effects of: a, maternal diet; b, cyclic-3',5'-adenosinemonophosphate (cyclic AMP) and c, clofibrate on hepatic lipogenesis in fetal rats were studied. The experimental diets contained 22% protein, 40--50% carbohydrate, adequate vitamins, and minerals. In addition, the fat-containing diets were supplemented with either 15% corn oil, 25% corn oil, or 5% cholesterol + 10% oleic acid. In the clofibrate feeding studies, 0.3% (w/v) of the ethyl ester was added to a stock ration or to fat-free diet. Lipogenesis was measured in liver slices incubated with [2-14C]pyruvate, [1-14C]acetate, or 3H2O. In addition, activities of lipogenic enzymes were measured in cytosol fractions from liver homogenates. The effec-s of the experimental diets on liver composition were also examined. Lipogenic activity was higher in fetal than in maternal liver. When 15% corn oil was added to the maternal diet, fatty acid synthesis in fetal liver did not decrease as it did in maternal liver. Maternal fasting decreased fetal fatty acid synthesys by 50% when measured with 14C and less than 10% when measured with 3H2O. Although the addition of cholesterol to the maternal diet decreased cholesterol synthesis in maternal liver, no such decrease was observed in fetal liver. Changes in enzyme activities paralleled alterations in lipogenesis in maternal but not in fetal liver. Corn oil feeding or fasting increased the rate of transfer of linoleate from the dam to the fetus. However, accumulation of linoleate in fetal liver did not correlate with a decreased rate of fatty acid synthesis as it did in maternal liver. Maternal hepatic glycogen stores were depleted by fasting, but glycogen levels in fetal liver remained high under these conditions.