Estrogens and atherosclerosis

Effect of 17-β-estradiol administration during adriamycin-induced cardiomyopathy in ovariectomized rat

The incidence of cardiovascular diseases in humans differs in relation to the age of the patient. Although women suffer less than men from cardiovascular disorders during 15-55 years, after this period the incidence is equivalent in both sexes. This data suggests a cytoprotective effect of estrogens against cardiovascular disease. The estrogens, especially 17-beta-estradiol, are important antioxidant molecules with potential cytoprotective properties during oxidant/antioxidant disbalance induced by oxidative stress. Oxidative stress is often the underlying mechanism during vascular alterations and cardiac damage. The present study evaluated the role of ovariectomy and/or 17-beta-estradiol administration on antioxidant status and lipid peroxidation during cardiac injury induced by adriamycin. Different parameters were measured, including hemodynamic response (arterial pressure and cardiac frequency), lipid peroxidation products (malondialdehyde), protein carbonylation, antioxidant status (reduced glutathione, glutathione peroxidase, superoxide dismutase and catalase), and cardiac injury (creatinine kinase, lactate dehydrogenase, aspartate and alanine aminotransferase). Our study showed that 17-beta-estradiol reduced all of the parameters related to oxidative stress and cardiac injury in ovariectomized rats treated with adriamycin.

The Effect of Hormone Replacement Therapy on Oxidized Low Density Lipoprotein Levels and Paraoxonase Activity in Postmenopausal Women

Oxidized low-density lipoproteins (oxLDL) are involved in initiation of atherosclerosis. Paraoxonase 1 (PON1), the isoenzyme of PON, is located on high-density lipoprotein (HDL) and protects against the oxidative modification of both HDL and LDL by hydrolysing lipid peroxides. Postmenopausal women have a higher risk of cardiovascular events compared with premenopausal women. The aim of this clinical study was to evaluate the effects of hormone replacement therapy (HRT) on oxLDL and PON1 activity in menopausal status. The subjects included 45 healthy postmenopausal women, aged 43 to 57 years, and 30 premenopausal women with regular cycles, aged 31 to 40 years. None of the participating women had a history of hypertension, diabetes mellitus or medications known to affect the cardiovascular system. Twenty five of the postmenopausal women received conjugated estrogens at dose of 0.625 mg/day per oral (P.O.) and medroxyprogesterone acetate (MPA) (1 mg/d P.O.) for 10 days. Twenty of the postmenopausal women received 17-beta estradiol (2 mg/day) and norethysterone acetate (NETA) (5 mg/day P.O.) for 10 days. Fasting blood samples were taken from premenopausal women (baseline) and postmenopausal women after HRT of 6 months to determine serum malondialdehyde (MDA), oxLDL, and PON1 activity. After 6-month therapy, MDA and oxLDL levels showed a statistically significant reduction in the treated groups versus baseline (p <0.05), whereas PON1 activities were increased (p <0.05). Increase in oxidative status may be one of the factors leading to reduction in PON1 activity and increased oxLDL in menopause. HRT may be effective on oxidative stress and lipoprotein metabolism in apparently healthy postmenopausal women.

Effects of estrogen and psychological stress on plasma homocysteine levels

OBJECTIVE

To investigate the effects of estrogen (E) and psychological stress on plasma total homocysteine levels in relation to menopausal status.

DESIGN

Double-blind, randomized, placebo-controlled study.

SETTING

The General Clinical Research Center of a university hospital.

PATIENT(S)

Thirty-six postmenopausal women and 26 premenopausal women. Both samples were healthy nonsmokers.

INTERVENTION(S)

Both premenopausal and postmenopausal women were subjected to a 6-minute psychological stressor. Postmenopausal women were randomized to one of three treatment arms: 2 mg of E2 or 2 mg of E2 + 5 mg of medroxyprogesterone acetate (MPA), or a placebo, all of which were given orally for 3 months. The psychological stressor was readministered after the 3-month regimen.

MAIN OUTCOME MEASURE(S)

Plasma total homocysteine levels were measured before and after the psychological stressor on one occasion for premenopausal women and before and after hormone replacement or placebo for postmenopausal women.

RESULT(S)

There were no significant differences in homocysteine levels between premenopausal (7.2 +/- 1.7 micromol/L; mean +/- SD) and postmenopausal women (7.9 +/- 2.06; mean +/- SD). There was no effect of stress or hormone replacement on homocysteine levels.

CONCLUSION(S)

Psychological stress, menopausal status, and oral hormone replacement therapy (HRT) do not affect plasma total homocysteine levels in women with normal basal homocysteine levels.

Autonomic and cardiovascular function in postmenopausal women: the effects of estrogen versus combination therapy

OBJECTIVE

This study examined the effects of oral estrogen (ERT) alone versus oral estrogen/medroxyprogesterone acetate (HRT) therapy on cardiovascular function, as controlled by the autonomic nervous system.

STUDY DESIGN

Forty-three postmenopausal women received ERT, HRT, or a placebo for 3 months in a double-blind, randomized, placebo-controlled study. Cardiovascular hemodynamics and heart rate variability were assessed at rest and during stress.

RESULTS

After 3 months of therapy, oral HRT significantly increased high-frequency power (P =.0002) and decreased total peripheral resistance (P =.04). The changes were evident at rest and during stress.

CONCLUSION

Our findings suggest that combination therapy produces a more favorable alteration of autonomic cardiovascular function than estrogen alone (ie, combination therapy increases vagal activity).

Age-related deterioration in arterial structure and function in postmenopausal women: impact of hormone replacement therapy

Epidemiological evidence suggests that hormone replacement therapy (HRT) reduces morbidity and mortality from cardiovascular diseases in postmenopausal women. In this study, indices of arterial function [total systemic arterial compliance (SAC) and carotid arterial distensibility coefficient (DC)], structure [carotid intima-media thickness (IMT)], and lipid profiles were compared in postmenopausal women on long-term HRT and aged-matched controls. One hundred nine women aged 44 to 77 years taking HRT and an age-matched group of 108 female controls were entered into the study. The two groups were similar for body mass index, smoking status, exercise level, alcohol intake, and blood pressure. Fasting cholesterol, low density lipoprotein, and lipoprotein(a) were reduced and high density lipoprotein increased in the HRT group. IMT increased with age; SAC and DC were reduced with age in both groups. The HRT group had a higher mean SAC (0.42+/-0.02 versus 0.34+/-0.02 U/mm Hg, P=0.0001) and a lower mean IMT (0.67+/-0.01 versus 0.74+/-0.02 mm, P=0.006) than did controls. Subgroup analysis for estrogen versus estrogen plus progestin revealed no differences for SAC and IMT; DC, however, was greater in estrogen-only users. Smokers on HRT had a higher mean SAC (0.41+/-0.02 versus 0.31+/-0.01 U/mm Hg, P=0.008) and a lower IMT (0.65+/-0.02 versus 0.75+/-0.03 mm, P=0.002) than did smokers not taking such therapy. A protective effect of long-term estrogen therapy on age-related changes in arterial structure and function in postmenopausal women was evident in smokers and nonsmokers alike. Progestin appeared to counteract the effects of estrogen on carotid compliance only. Long-term controlled trials are needed to determine the significance of these findings.

Clinical pharmacology of estrogens: cardiovascular actions and cardioprotective benefits of replacement therapy in postmenopausal women

The use of estrogens in postmenopausal women has been the subject of much controversy regarding hormone formulation, dosage, use in combination with progestins, duration of treatment, and contraindications. Estrogens have been prescribed to relieve menopausal symptoms for more than three decades. The hormones reduce the gynecologic and psychologic changes associated with menopause while inhibiting bone resorption and possibly reducing the risk of cardiovascular disease. Their use however has been complicated by an increased risk of endometrial cancer and possibly breast cancer. The use of estrogens as cardioprotective agents is discussed and the clinical experiences and the possible mechanisms of action are reviewed. The clinical pharmacology of estrogens and the various formulations that are available as monotherapy or in combination with progestins will also be reviewed.

Clinical pharmacology of estrogens: cardiovascular actions and cardioprotective benefits of replacement therapy in postmenopausal women

The use of estrogens in postmenopausal women has been the subject of much controversy regarding hormone formulation, dosage, use in combination with progestins, duration of treatment, and contraindications. Estrogens have been prescribed to relieve menopausal symptoms for more than three decades. The hormones reduce the gynecologic and psychologic changes associated with menopause while inhibiting bone resorption and possibly reducing the risk of cardiovascular disease. Their use however has been complicated by an increased risk of endometrial cancer and possibly breast cancer. The use of estrogens as cardioprotective agents is discussed and the clinical experiences and the possible mechanisms of action are reviewed. The clinical pharmacology of estrogens and the various formulations that are available as monotherapy or in combination with progestins will also be reviewed.

Menopause

In brief Women experience many changes during menopause and the climacteric. Physical changes can affect nearly every organ system; social and psychological changes can cause fear and anxiety. However, by exercising, a woman can improve her quality of life and mitigate the negative effects of these changes. Exercise can improve cardiorespiratory fitness, reduce the risk of coronary artery disease, and prevent osteoporosis. Establishing exercise guidelines for menopausal patients can help them reap the advantages of an exercise program.

The association between moderate alcoholic beverage consumption and serum estradiol and testosterone levels in normal postmenopausal women: relationship to the literature

The major source of endogenous estrogens in postmenopausal women is the aromatization of androgens to estrogens; because alcohol is known to increase aromatization, the relationship between moderate alcoholic beverage consumption and serum estradiol levels was evaluated in 128 normal postmenopausal women. Alcohol intake was based on a composite of self-report and food record information. Among the 78.8% of women reporting alcohol use, weekly intake was 4.8 +/- 0.6 drinks. Among abstainers, estradiol levels were 100.8 +/- 12.1 pmol/liter, significantly lower than in alcohol users, 162.6 +/- 11.9 pmol/liter. Significant bivariate correlations were found between the logarithm of estradiol and total weekly drinks. In multiple linear regression analyses inclusion of alcohol as a variable increased the amount of explained variation in estradiol. Similar findings were demonstrable when the crude estimator of aromatization, the estradiol:testosterone ratio logarithm was the dependent variable. Together, these findings suggest that moderate alcohol use is an important factor for postmenopausal estrogen status and may offer a partial explanation for the reported protective effect of moderate alcohol consumption with respect to postmenopausal cardiovascular disease risk.

Progestins and Antiprogestins: A Review of Their Role in Medicine and Bioassays Used in Their Development

The physiological role of ovarian progesterone in reproduction and the medical uses of synthetic progestins and antiprogestins are briefly reviewed. Although a number of progestins are in wide use, the search continues for better analogues that display fewer of the unwanted effects of the present compounds. The one antiprogestin approved for human use to date, RU486, exhibits considerable antiglucocortoid activity

The classical bioassays currently in use for the development of these steroid analogues depend upon in vivo progestin effects. However, progestins induce measurable responses in several cell culture systems that could be used as alternative bioassays. Rabbit uterine stromal cells in primary culture are especially suitable for such use. Addition of progesterone to these cultures stimulates synthesis of a 42 kilodalton (42kD) protein that appears in the medium. The 42kD protein response is specific for a progesterone receptor-mediated event and it can be blocked by known progestins. Using this culture system as a bioassay, one rabbit yields enough cells to measure the effect of 30 test doses in triplicate. Thus, a culture system is described that could substitute for current in vivo bioassays. This culture bioassay would allow large scale screening for potential progestin or antiprogestin activity.

Effects of moderate consumption of alcoholic beverages on endocrine function in postmenopausal women. Bases for hypotheses

That alcoholic beverage consumption has not yet received attention as a variable that might influence the estrogenization of postmenopausal women is discussed within the context of the growing proportion of postmenopausal women in the population, their disease risk vis-à-vis estrogenization, and survey findings that report that the majority of postmenopausal women use alcoholic beverages to at least some degree. The available literature is reviewed concerning the effects of acute or chronic ethanol administration, alcoholic beverage consumption, or the administration of phytoestrogen-containing congeners of bourbon on the endocrine status of postmenopausal women or relevant animal models. The basic components of postmenopausal endocrine function and the factors known to affect endocrine status are presented. The importance of incorporating known endocrine-modulating factors into the design of future studies so as to maximize the detection of alcohol effects in postmenopausal women is emphasized.

Sex, plasma lipoproteins, and atherosclerosis: prevailing assumptions and outstanding questions

We review the hypothesis that the incidence of coronary heart disease (CHD) is higher in men than in women due to differences in plasma lipoprotein risk factors between the sexes. Men and women appear to be equally susceptible to the effects of lipoprotein risk factors for CHD, and the difference between the sexes in lipoprotein risk factors for CHD appears to be consistent with their being, at least in part, responsible for the sex difference in CHD. This is apparent both when men and women of equal age are compared, and when age-related variations in the sex differences in plasma lipoproteins and CHD are considered. Differences between the sexes in lipoprotein concentrations are still present when sex differences in adiposity, cigarette smoking, physical activity, and diet are taken into account. Evidence relating these sex differences in CHD and lipoproteins to the effects of sex hormones is critically examined. It is commonly accepted that androgens induce changes in lipoprotein concentrations that would predispose towards CHD, whereas estrogens are held to have opposite effects. However, much of the evidence for this comes from studies of changes associated with administration of synthetic gonadal steroids or with changes in gonadal function. Studies of differences in lipoprotein metabolism in normal men and women are extremely limited. In males high-density lipoprotein (HDL) cholesterol levels fall at puberty, correlating with the rise in plasma testosterone concentrations. In females, HDL levels do not change at puberty, despite the rise in estrogen concentrations. Evidence for lipoprotein changes during the menopause, when estrogen levels decline, is equivocal. Similarly, the evidence for an increase in CHD incidence at the menopause is inconclusive. National mortality data indicate that the decreasing sex difference in CHD after 50 years of age is due to a declining rate of increase in men rather than to an acceleration in CHD incidence in women. In men the age-related increase in low-density lipoprotein (LDL) concentrations diminishes beyond 50 years of age, whereas in women the rate of increase remains unchanged. Studies of the effects of gonadectomy are of doubtful relevance in assessing the roles of sex hormones in CHD, and have not been performed with sufficient rigor to provide definitive conclusions.(ABSTRACT TRUNCATED AT 400 WORDS)

Hormonal replacement therapy: benefits, risks, doses

This chapter presents information on the indications for the use of post menopausal hormone therapy. Side effects and risks of this form of therapy are also summarized. Recommendations are made concerning the clinical management of patients receiving hormone treatment.

Protein-bound homocyst(e)ine in patients with rheumatoid arthritis undergoing D-penicillamine treatment

Protein-bound homocyst(e)ine was measured in the plasma of 38 nonhomocystinuric patients with rheumatoid arthritis. Nineteen of them were treated orally with D-penicillamine 100-1,500 mg/d for a period of one month to 15 years. For these patients, the mean +/- standard deviation level of plasma protein-bound homocyst(e)ine was 1.95 +/- 1.07 nmol/mL. In contrast, the mean plasma level of protein-bound homocyst(e)ine was 4.72 +/- 1.11 nmol/mL in the 19 patients who had not been treated with oral D-penicillamine. There was a statistically significant difference (P less than .0001) in the plasma protein-bound homocyst(e)ine concentrations between patients with and without oral D-penicillamine therapy. Thus, it may be speculated that oral D-penicillamine may be beneficial in protecting patients from the development of thromboembolism and arteriosclerosis.

Unique efficiency of methionine metabolism in premenopausal women may protect against vascular disease in the reproductive years

Premenopausal women develop occlusive artery disease less frequently than postmenopausal women. In coronary heart disease, higher blood levels of homocysteine-cysteine mixed disulphide have been reported. Therefore, in healthy subjects, we studied the role of menopausal status in the transsulphuration of methionine in 10 premenopausal and 10 postmenopausal women. To exclude the role of aging, we compared these results with those in 10 younger and 10 older men of comparable age groups. An oral methionine load (0.1 g/kg of body weight) was administered after overnight fasting. Before and during 8 h, thereafter, serum levels of methionine, homocystine, and homocysteine-cysteine mixed disulphide were measured. In the fasting state, serum methionine levels were similar in the premenopausal women and both groups of men. Postmenopausal women had significantly lower fasting levels. Peak levels and clearances of methionine after loading did not differ between the groups. In the fasting state, homocystine was never detectable; yet, after methionine loading, slight homocystinemia was present in 12 out of 20 men, and was more pronounced in all postmenopausal women. However, homocystinemia did not occur in any of the premenopausal women after loading. Fasting serum homocysteine-cysteine mixed disulphide levels did not differ between both groups of men and postmenopausal women. In premenopausal women, both fasting and postloading disulphide levels were significantly lower than in any other group. We conclude that premenopausal women have a unique efficiency of methionine handling, and thereby are preserved against the accumulation of homocysteine after methionine loading. We speculate that this phenomenon might account for the lower incidence of vascular disease in women in the reproductive life cycle.

A study of the mechanism of estrogen as an antiatherosclerotic: the inhibitory effect of estrogen on A23187-induced contraction of the aortic wall

Although the antiatherosclerotic effects of estrogen are well known, the mechanisms involved have not been determined. We designed experiments in which strips of thoracic aorta from oophorectomized rabbits were contracted by the calcium ionophore A23187 and the inhibition of the contraction by estrogen and concomitant levels of cyclic nucleotides were determined. A23187 (10(-5) M) increased the tension slowly but progressively, and there was a concomitant decrease in cyclic AMP levels. While a dose-dependent relaxation occurred in strips contracted by A23187 with addition of theophylline (greater than 10(-4) M) or dibutyryl cyclic AMP (greater than 10(-4) M) to the bath, prior addition of these compounds inhibited the contraction. Pretreatment of the strips with estrogen (2 x 1-(-7) M, 2 x 10(-5) M) significantly prevented contraction of the strips, as induced by A23187, and also prevented reduction in cyclic AMP levels, as induced by the ionophore. Cyclic GMP levels remained unchanged throughout. As the contraction of these tissues wall was inhibited by estrogen in an apparent association with a reduction in the levels of cyclic AMP, this might help to explain the antiatherosclerotic effects of estrogen, as reduction in these nucleotide levels has been suggested to induce atherosclerotic lesions in the arterial wall by enhancing vascular permeability.

Menopausal oestrogen therapy and protection from death from ischaemic heart disease

The medical records of a Los Angeles retirement community were examined to find out the association between oestrogen replacement therapy and death from ischaemic heart disease. Women dying from ischaemic heart disease over a five-year period were compared with living and deceased control groups; both controls were matched with cases for date of birth, date of entry into the community, race, and socioeconomic status. The deceased control was also matched for date of death. Compared with living controls cases using conjugated oestrogens had a risk ratio for death from ischaemic heart disease of 0.43 (95% confidence interval 0.24-0.75). Comparison with deceased controls gave a similar relative risk. This association was not due to identifiable confounding factors. Other risk factors for ischaemic heart disease, including hypertension, diabetes, stroke, angina pectoris, and heavy cigarette smoking, were confirmed by this study.