EFFECT OF HORMONE REPLACEMENT THERAPY ON THE SUSCEPTIBILITY OF LOW-DENSITY-LIPOPROTEIN TO OXIDATION AMONG POSTMENOPAUSAL HYPERCHOLESTEROLEMIC WOMEN

The effect of sequential combined hormone replacement therapy on the s usceptibility of low-density lipoprotein to oxidative modification was investigated in a double-blind, randomized placebo-controlled study. Hypercholesterolaemic, postmenopausal women were supplemented with 17 beta-oestradiol and norethisterone acetate (n = 13 subjects) or placeb o capsules (n = 15 subjects) for 12 weeks. They were instructed to fol low the American Heart Association step one diet. Low-density lipoprot ein, isolated before and after treatment, was subjected to copper-cata lysed lipid peroxidation. There were no significant differences betwee n low-density lipoprotein from the hormone replacement therapy and pla cebo groups, as assessed by measuring the lag time for formation of co njugated dienes, the rate of formation and the amount of conjugated di enes formed, the amount of lipid peroxides generated, and the relative electrophoretic mobility at baseline and after treatment. Dietary rec ords showed that the subjects were consuming similar amounts of fat an d vitamins. No major differences were found in the fatty acid pattern of low-density lipoprotein from the two groups. In conclusion, the res ults indicated that hormone replacement therapy with 17 beta-oestradio l sequentially combined with norethisterone acetate in non-smoking, hy percholesterolaemic, postmenopausal women has no protective effect on the susceptibility of low-density lipoprotein to copper-catalysed modi fication in vitro.