Increased activity of lecithin: Cholesterol acyltransferase during short-term oral estrogen progestin replacement therapy in a group of postmenopausal women

Abstract

The aim of the study was to assess the short-term effect of estrogen-progestin therapy on the plasma level of lecithin: cholesterol acyltransferase ([LCAT] EC 2.3.1.43), a key enzyme in the cholesterol reverse-transport process. The trial included 21 women with at least 6 months of menopause, which was confirmed by anamnesis, physical evaluation, and follicle-stimulating hormone (FSH) determination. Women receiving pharmacological treatment or who had any kind of endocrine disorder were excluded. In addition, we evaluated and confirmed normal Papanicolaou and mammography tests in all 21 women included in the trial. They received conjugated equine estrogen 0.625 mg daily, plus cyclic medroxyprogesterone acetate (5 mg daily) for 12 days each month. Plasma levels of LCAT, cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides, apoB, and apoAl were evaluated before and after 1 and 3 months of therapy. Pretherapy and posttherapy results were analyzed statistically by Wilcoxon's rank-sum test for paired samples. No significant changes were observed either for body mass index or for blood pressure. A significant increase in plasma LCAT activity was found at the first and third month posttherapy ( P < .005). In addition, after 3 months of therapy, HDL-C significantly increased ( P < .005), in contrast to the significant decrease detected in total cholesterol ( P < .025), LDL-C ( P < .005), cholesterol to HDL-C and LDL-C HDL-C ratios ( P < .005). Triglyceride levels did not show significant modification. In conclusion, our results indicate that short-term estrogen-progestin therapy produces a significant increase in plasma LCAT activity, as well as beneficial changes in the lipid profile, in postmenopausal women.