Prolonged hyperinsulinemia reduces plasma fatty acid levels in the major lipid groups in fetal sheep.

The offspring of women with poorly controlled diabetes have increased total body fat. Experimental fetal hyperinsulinemia has previously been associated with increased fat accumulation in rhesus monkey fetuses and increased lipid content and lipogenesis in rat fetuses. We hypothesized that prolonged fetal hyperinsulinemia would alter plasma total fatty acids and the individual fatty acids in each major lipid group. Fatty acids determined by gas-liquid chromatography were measured in the arterial blood of 12 chronically catheterized fetal sheep after 10 to 12 days of insulin (n = 7) or placebo (n = 5) infusion. Plasma concentrations of insulin were 412 +/- 63 microU/ml and 9 +/- 3 microU/ml (mean +/- SE) in the insulin- and placebo-treated fetal sheep, respectively. Prolonged fetal hyperinsulinemia was associated with lower circulating total fatty acid levels in each lipid class except cholesterol esters. Although the precursor of arachidonic acid, 18:2 (linoleic acid), was not decreased in any lipid class, insulin infusion was associated with reduced arachidonic acid in each lipid class. We conclude that prolonged fetal hyperinsulinemia decreases circulating total fatty acid and the individual fatty acids in each of the major lipid classes, except for the cholesterol esters. We speculate that these reductions in circulating fatty acids represent an insulin-mediated increase in tissue deposition.