Effects of estrogen replacement therapy on serum lipid values and angiographically defined coronary artery disease in postmenopausal women

Serum lipoprotein changes after orchidectomy and treatment with oestrogens and luliberin analogues in male Sprague-Dawley rats

The effect of androgen deprivation on lipoprotein profile and cardiovascular risk in men with advanced prostatic carcinoma is a matter of controversy. We describe an experimental model to evaluate the effects of orchidectomy and oestrogen and luliberin analogue administration on lipoprotein profiles in male Sprague-Dawley rats. Eighty rats were divided into three treatment groups and a control group. Results were compared with the scanty human data found in the literature. The oestrogen group was that which showed more differences compared with the control group, but its lipoprotein profile differed from that obtained in humans. Orchidectomy and luliberin analogue groups showed fewer differences than the oestrogen group, but a non-favourable lipoprotein profile in terms of cardiovascular risk was observed. There were important differences between humans and rats with regard to lipoprotein profile, suggesting that rats are probably not a good model for the study of atherogenic risk.

Sex steroids and lipoprotein metabolism

Lipoprotein metabolism is involved in atherogenesis. Female sex-hormones have substantial effects on both lipoprotein metabolism and the vessel wall. Cholesterol, one of the major lipids in lipoproteins, is both the substrate for, and the target of, the steroidal sex hormones.

Unanswered questions in hormonal replacement therapy

This review addresses many of the unanswered questions existing relative to the use of exogenous estrogens and progestins in postmenopausal women (PMW). The literature in the field is reviewed and summarized, with a particular effort to identify key questions of major concern. The effect of selection bias on conclusions reached from retrospective studies involving hormone replacement therapy (HRT) has not been examined. Less is actually known about the effects of progestins than estrogens. Many of the endocrine changes that occur with aging remain poorly defined. Effects of estrogens and progestins on the breast and on breast cancer are unclear. Estrogens have recognized beneficial effects and progestins have detrimental effects on lipoprotein metabolism. Estrogens also have direct effects on the vasculature and may impact on cardiovascular risk in other ways. Although estrogens are the only agents known to eliminate hot flushes, the mechanism by which flushes arise is not known. Estrogens may have ameliorating effects on mood and behavior and may improve dementia, but research in this area has been limited to date. Lastly, the preferred estrogens and progestins, their dosages and routes of administration, remain to be more completely defined.

Human vascular smooth muscle cells contain functional estrogen receptor

BACKGROUND

The decreased incidence of coronary artery disease observed in postmenopausal women given estrogen (E2) replacement demonstrates an atheroprotective effect of E2 that is generally believed to be mediated by indirect, E2-induced changes in cardiovascular risk factor profiles. We hypothesized that the atheroprotective effect of E2 may be in part mediated by a direct effect of E2 on vascular smooth muscle cells (VSMCs). Therefore, a series of experiments was performed to determine whether human VSMCs contain a competent E2 receptor, a ligand-activated transcription factor known to mediate E2-induced effects in nonvascular cells.

METHODS AND RESULTS

Ribonuclease protection assays, with a probe derived from the human E2 receptor, were used to demonstrate E2-receptor mRNA in human saphenous vein VSMCs. To show that VSMCs contain E2-receptor protein as well as message, immunoblotting and immunofluorescence studies with a monoclonal anti-E2-receptor antibody were performed, and E2-receptor protein was detected by both methods. Transient transfection assays using a specific E2-responsive reporter system were used next to determine whether the VSMC E2 receptor is capable of E2-induced transcriptional transactivation. Initial studies using mammary artery-derived VSMCs resulted in a 2.4-fold increase in reporter activity in response to 10(-7) mol/L E2. Subsequent studies using saphenous vein VSMCs demonstrated increasing levels of reporter activation as the concentration of E2 was increased from 10(-9) mol/L (1.3-fold increase; SEM, 0.07; P = .05, n = 3) to 10(-7) mol/L (1.6-fold increase; SEM, 0.04; P = .002, n = 6). The specificity of the E2-induced transactivation of the reporter gene was shown by dose-dependent inhibition of transactivation by the pure E2 antagonist ICI 164,384 and by enhancement of the transactivation by simultaneous overexpression of the E2 receptor.

CONCLUSIONS

We have demonstrated for the first time that human VSMCs express E2-receptor mRNA and protein and that the E2 receptor in VSMCs is capable of estrogen-dependent gene activation. These data suggest a mechanism by which estrogen may directly alter VSMC function.

Relation of coronary artery disease in women < 60 years of age to the combined elevation of serum lipoprotein (a) and total cholesterol to high-density cholesterol ratio

After age 40 years, coronary artery disease (CAD) is the leading cause of death in both women and men, yet in women the factors associated with, or leading to, CAD have been less extensively studied. This study examined the strength of association of a number of risk factors to CAD in groups of women < 60 years of age with (n = 108) and without (n = 66) angiographically documented significant narrowing of coronary arteries. In univariate analyses, there were significant differences between control subjects and patients with regard to age (49 +/- 6 vs 52 +/- 7 years) and total lipids and apolipoproteins measured. The relative frequency of cigarette smoking and diabetes was higher and that of estrogen replacement therapy lower in patients with CAD than in control subjects. In multivariate analysis the following factors were independently associated with CAD (adjusted odds ratios and 95% confidence intervals): total cholesterol to high-density lipoprotein (HDL) cholesterol (1.91; 1.56 to 2.34); lipoprotein (a) (10.66; 3.51 to 32.35); estrogen replacement (0.24; 0.11 to 0.54); age (1.12; 1.04 to 1.18); and smoking (1.50; 0.98 to 2.29). The nonadjusted odds ratio of CAD, based on combined tercile values of lipoprotein (a) serum level and total cholesterol to HDL cholesterol ratio, was very low (0.15; 0.06 to 0.36) when both values were within the first tercile, but very high (16.63; 3.54 to 78.07) when both were in the third tercile.(ABSTRACT TRUNCATED AT 250 WORDS)

Estrogen and estrogen-progestogen replacement: therapy and cardiovascular diseases

The use of postmenopausal estrogens primarily to prevent heart disease should be reserved for women at high risk by virtue of an unfavorable low-density lipoprotein: high-density lipoprotein (LDL:HDL) ratio or the presence of manifest disease. Unopposed oral estrogen should improve lipoproteins within a few weeks, and this change, if sustained, should reduce the risk of cardiovascular disease. There is no reason to give progestins to a woman without a uterus. The management of a woman with an intact uterus is less well defined, given the unknowns about progestin's long-term effects on lipids or the heart.

Value of a simple measure of estrogen status for improving the diagnosis of coronary artery disease in women

PURPOSE

To determine the potential impact of estrogen status on the pretest and postexercise test diagnostic accuracy of exercise testing.

PATIENTS AND METHODS

The study comprised a total of 234 women and 326 men who underwent exercise testing followed by coronary angiography. We performed incremental logistic regression analysis of pretest (age, symptoms, smoking, diabetes, cholesterol level) with and without estrogen status (defined according to menopausal and oral estrogen status) and exercise test (two ST-segment and three non-ST-segment) variables separately for men and women. Outcomes were assessed by receiver operating characteristic (ROC) curve area analysis.

RESULTS

Estrogen status was an independent pretest predictor of angiographic coronary disease. Pretest ROC curve areas: women without estrogen status = 0.79, women with estrogen status = 0.85, men = 0.78 (women with estrogen status versus other groups, p < 0.001). Postexercise test ROC curve areas: women without estrogen status = 0.83, women with estrogen status = 0.87, men = 0.88 (women without estrogen status versus other groups, p < 0.001).

CONCLUSION

Consideration of estrogen status allowed for a significant improvement in the pretest clinical diagnosis of coronary disease in women. When these improvements were added to the results of exercise testing, the diagnostic accuracy of the combined clinical and exercise test data was similar for men and women. Estrogen status may be an important diagnostic clinical variable in women with suspected coronary disease.