Effect of conjugated equine estrogen in combination with two different progestogens on the risk factors of coronary heart disease in postmenopausal Chinese women in Taiwan: a randomized one-year study

The effects of progesterones on blood lipids in hormone replacement therapy

The safety of progestogens as a class has drawn much attention after the publication of data from the Women’s Health Initiative (WHI) trial, particularly with respect to cardiovascular disease. Depending on the chemical structure, pharmacokinetics, receptor affinity and potency of action, progestogens have a divergent range of properties that may translate to very different clinical effects. The purpose of this review is to describe the role of varied progestogens in hormone replacement therapy (HRT), especially focusing on blood lipids, which are the most important parameters for assessing cardiovascular disease risk.

Differential effect of hormone therapy and tibolone on lipids, lipoproteins, and the atherogenic index of plasma

The aim of our study was to assess the effect of various regimens and doses of hormone therapy and tibolone on the Atherogenic Index of Plasma (AIP). A total of 519 postmenopausal women attending our menopause clinic were studied in a prospective design. Women with climacteric symptoms were randomly assigned to receive 1 of the following regimens: tibolone 2.5 mg, conjugated equine estrogens 0.625 mg plus medroxyprogesterone acetate 5 mg (CEE/MPA), 17beta-estradiol 2 mg plus norethisterone acetate 1 mg (E2/NETA), or 17beta-estradiol 1 mg plus norethisterone acetate 0.5 mg (low E2/NETA). Serum parameters were assessed at baseline and after 6 months and included total cholesterol, LDL-cholesterol, HDL-cholesterol, triglycerides, apolipoprotein A1 and apolipoprotein B. The AIP was assessed as the log (triglycerides [mmol/L]/HDL-C [mmol/L]). CEE/MPA treatment associated with lower mean LDL-C but higher mean triglyceride levels (-15.5 mg/dL +/- 3.6, P = 0.0001; 12.6 mg/dL +/- 4.8, P = 0.01). Furthermore, CEE/MPA treatment resulted in higher AIP levels (0.073 +/- 0.021, P = 0.001). On the contrary, both E2/NETA regimens and tibolone associated with lower mean triglyceride and HDL-C levels (E2/NETA, triglycerides: -9.8 mg/dL +/- 5.0, P = 0.049; HDL-C: -4.9 mg/dL +/- 1.8, P = 0.01, low E2/NETA triglycerides: -12.5 mg/dL +/- 4.1, P = 0.003; HDL-C: -4.7 mg/dL +/- 1.3, P = 0.001; tibolone, triglycerides: -21.9 mg/dL +/- 2.7, P = 0.0001; HDL-C: -12.7 mg/dL +/- 1.1, P = 0.0001). None of the 3 regimens had any effect on AIP. The effect of a particular regimen of hormone therapy on the lipid-lipoprotein profile differs depending on the parameter assessed. The use of unified markers such as AIP will be helpful in evaluating the overall effect of lipid-lipoprotein modulation on the cardiovascular system. In fact, the concurrent assessment of the therapy effect on both LDL-C and AIP may be more dependable in evaluating the cardiovascular impact of a given regimen.

The effect of hormone replacement therapy on the levels of serum lipids, apolipoprotein AI, apolipoprotein B and lipoprotein (a) in Turkish postmenopausal women

OBJECTIVES

Estrogen replacement therapy alters the lipid profiles favorably for delaying atherosclerosis in postmenopausal women. The effects of estrogen plus progesterone combination therapy on lipids are controversial. This study was designed to evaluate the effect of female sex hormones on lipids and lipoproteins and to clarify the influence of progesterone on the effect of estrogen in postmenopausal women.

METHODS

Of the 60 postmenopausal women admitted to our menopause clinic, 40 had intact uterus and received continuous 0.625 mg conjugated equine estrogen (CEE) plus 2.5 mg medroxyprogesterone acetate (MPA), whereas the remaining 20 were hysterectomized and received 0.625 mg CEE daily. To assess the alterations in lipids and lipoproteins during menopause, 45 healthy premenopausal women were investigated. Lipid and lipoprotein levels were assessed in each subject at baseline and at the 6th and 18th months of therapy.

RESULTS

In menopause, a shift towards more atherogenic lipid and lipoprotein profiles than those of the premenopausal state was found. Following 18 months of treatment, both regimens reduced total cholesterol (TC) levels as compared with the baseline (6.4 vs. 6.9% in the CEE/MPA and CEE groups, respectively). The CEE group had a more pronounced increase in high-density lipoprotein (HDL) cholesterol than the CEE/MPA group (10.3 vs. 8.8%, respectively). Both groups displayed reduced TC, low-density lipoprotein (LDL) cholesterol and apolipoprotein-B (ApoB) concentrations, whereas triglycerides increased, with a greater tendency to increase in the CEE/MPA group at the end of the trial. Also, the lipoprotein (a) [Lp(a)] levels decreased significantly (27.6 vs. 24.5% in the CEE/MPA and CEE groups, respectively). This decrease was more pronounced in subjects with a relatively higher basal Lp(a) concentration.

CONCLUSION

Both treatment regimens caused positive alterations in the lipid and lipoprotein profiles. This association might play a pivotal role in the postmenopausal increases in atherosclerotic diseases and cardioprotective effect of estrogen in postmenopausal women.

Effect of Vitamin E on Lipid Parameters in Ovariectomized Rats

The risk of cardiovascular disease drastically increases at the onset of menopause, in part, because of rise in blood cholesterol and unfavorable changes in lipid profile. This study was designed to investigate the dose-dependent effects of vitamin E supplementation on lipid parameters in ovariectomized (ovx) rats. Sixty 12-month-old female Sprague-Dawley rats were either sham-operated (sham; one group) or ovx (four groups). All rats were maintained on a semipurified caseinbased diet (AIN-93M; 75 IU vitamin E/kg of diet) for a period of 120 days. Thereafter, ovx rats were placed on one of four doses of vitamin E treatment (75, 300, 525, or 750 IU vitamin E/kg of diet), while the sham group was continued on 75 IU vitamin E/kg of diet for 100 days. Ovariectomy tended to increase (by 24%, P = 0.1) serum non?high-density lipoprotein (HDL) cholesterol and decrease (by 14%, P = 0.1) HDL cholesterol. Vitamin E did not have any significant effects on serum lipid parameters. Liver total lipids were notably increased (P < .001) in ovx animals, and supplementation with vitamin E at 525 IU/kg of diet was able to significantly reduce liver total lipids by 13%. Additionally, ovariectomy caused an increase in serum glucose and liver C18:1 fatty acid concentrations along with decreases in C18:0, C20:4, and C22:6 fatty acid concentrations. These alterations on liver fatty acid profiles were unaffected by vitamin E. The findings of this study suggest that vitamin E supplementation moderately improves lipid parameters in ovarian hormone-deficient rats.