METABOLIC SYNDROME, OXIDATIVE STRESS AND LIPOPROTEINS: WHAT ARE THE BIOCHEMICAL EFFECTS OF WEIGHT LOSS?

Aim. To examine and compare the composition and the oxidisability of the hydrophobic core and amphipathic surface of lipoproteins in a group of adult males with metabolic syndrome before and after weight loss of at least 5% of their initial weight following a hypocaloric diet. Methods. The concentration of cholesterol, triglycerides, phospholipids, and proteins was studied to analyse the chemical composition of lipoproteins. Pyrenyl-cholesteryl ester and pyrenyl-phosphatidylcholine, incorporated into the hydrophobic core or amphipathic surface of LDL and HDL, respectively, were used for measuring 2,2'-azobis-2-methyl- propanimidamide-dihydrochloride-induced peroxidation kinetics in these regions. Results. In comparison with the initial time, there was an improvement of HDL oxidisability with an increase of lag-time and a reduction of the velocity of propagation of peroxidation in the core of HDL. Parallel but opposite, there was a worsening in the susceptibility to peroxidation of LDL with a reduction in lag-time and an increased propagation rate of peroxidation in the LDL core. After weight loss, LDL showed a higher content of triglycerides whereas HDL showed reduced triglycerides content. In both LDL and HDL, the increase in the percentage of triglycerides was connected with an increased propagation rate of peroxidation kinetic and with a reduction of the lag-time in the hydrophobic core. Conclusions. A more detailed knowledge of the chemical composition and oxidisability of both the surface and core of lipoproteins could be a useful additional means for better understanding the mechanisms that link the changes in lipoproteins metabolism to the risk of cardiovascular disease in patients with metabolic syndrome after weight loss.