Copper Deficiency Increases the Susceptibility of Lipoproteins and Tissues to Peroxidation in Rats

Abstract

Male Wistar rats were pair-fed from weaning for 6 wk either a copper-deficient diet or a control diet containing sucrose. Hypercholesterolemia in copper-deficient animals was associated with a significantly greater plasma apolipoprotein B concentration and modifications in the lipid composition of triglyceride-rich lipoproteins containing apolipoprotein B. The proportion of triglycerides was elevated and the proportion of cholesterol was reduced in the VLDL + LDL fractions from copper-deficient rats compared with control animals. When the VLDL + LDL fractions were subjected to in vitro copper-induced oxidation, the lipoprotein fractions from copper-deficient rats were more susceptible to oxidative damage than lipoprotein fractions from control rats as indicated by the rate of diene conjugation. Hydroperoxide and thiobarbituric acid-reactive substance (TBARS) measurements performed 3 h after the induction of peroxidation were in agreement with the greater formation of conjugated dienes. Concentrations of TBARS were significantly greater in heart homogenates from copper-deficient rats compared with control rats. After exposure of tissue homogenates to iron-induced lipid peroxidation, TBARS were significantly higher in liver and heart from copper-deficient rats compared with control rats. Of particular importance is the observation that copper deficiency has a harmful effect on lipid peroxidation in the cardiovascular system.