Zinc deficiency impairs whole body accumulation of polyunsaturates and increases the utilization of [1-14C]linoleate for de novo lipid synthesis in pregnant rats

Abstract

Zinc deficiency impairs the metabolism of polyunsaturates, but the degree to which its effects are independent of food intake are still in question. Identical amounts of a semiliquid control diet (26.4 mg zinc/kg) or moderately zinc deficient diet (3.2 mg zinc/kg) were tube fed to rats for 11 days during the second half of pregnancy to evaluate the specific effects of zinc deficiency on maternal utilization and fetal accumulation of polyunsaturates. The whole body fatty acid balance method was used to determine net accumulation of polyunsaturates and their whole-body disappearance. Incorporation of14C from [1-14C]linoleate into maternal and fetal lipid classes was also studied on days 20–21. At term, zinc-deficient rats had significantly higher whole-body disappearance of linoleate and α-linolenate and lower accumulation of n−6 and n−3 long-chain polyunsaturates. Zinc-deficient rats had higher14C activity in free cholesterol, saturates, and monounsaturates in several maternal organs but not in the fetuses. We conclude that during pregnancy, moderate zinc deficiency not affecting food intake or weight gain still alters whole-body metabolism of linoleate and α-linolenate towards increased β-oxidation and also increases the utilization of carbon from linoleate for de novo lipid synthesis.Key words: cholesterol, linoleate, α-linolenate, oxidation, polyunsaturates, pregnancy, zinc.