INCREASED LOW-DENSITY-LIPOPROTEIN PEROXIDATION IN ELDERLY MEN

Background Oxidative modification of low-density lipoprotein (LDL) app ears to play a pivotal role in atherogenesis. The specific role played by LDL peroxidation in aging is not known, Since estrogens may protec t LDL from peroxidation in vitro and in vivo, we chose to investigate only men of various ages. Objective To determine whether LDL from heal thy elderly men was differently susceptible to peroxidation than LDL o f young and adult men. Subjects and methods LDL was isolated from 15 n ormolipidemic young (aged 19-23 years), 17 adult (aged 35-55 years), a nd 16 elderly (aged 77-90 years) healthy men. None of the men included in the study was a smoker or a hypertensive. LDL peroxidation was ach ieved by exposure to 5 mu mol/l copper sulfate for 18 h at 37 degrees C, and some markers of lipid peroxidation (estimating various levels o f peroxidation) were evaluated. Results The levels of lipid peroxides in LDL from our elderly men were already higher under basal conditions than were those both of adult and of young men. LDL from elderly men was more susceptible to peroxidation than was that of adult and young men. Furthermore, the lag time correlated inversely to age (r = -0.68, P< 0.01), whereas lipid peroxide and malonyldialdehyde levels correla ted highly to age (r = 0.79 and r = 0.77, P< 0.0002 and P< 0.0012, res pectively). With aging the vitamin E content in LDL decreased whereas the arachidonic fatty acid content increased. More importantly, the re lationship between the vitamin E content and the lag time made evident the parallel increase in lag time and in vitamin E level with aging. The vitamin E concentration also correlated inversely to levels of thi obarbituric acid-reactive substances in LDL from elderly patients (r = -0.61, P < 0.05). Conclusions The present study shows that LDL peroxi dation increases with age. This phenomenon may favor the progression o f atherosclerosis in elderly men.