Ovarian sex steroids and atherosclerosis

Gender Differences in Atherosclerotic Vascular Disease: From Lipids to Clinical Outcomes

Cardiovascular diseases (CVDs) are one of the main reasons of death and morbidity in the world. Both women and men have high rates of cardiovascular morbidity and mortality, although gender-related differences in mortality and morbidity rates are observed in different age groups of the population. In the large cohort of cardiovascular disease, ischemic heart disease (IHD), heart failure (HF), systemic hypertension, and valvular heart disease are particularly common in the population. CVDs caused by atherosclerosis are in the first place in terms of frequency, that is why society is particularly interested in this problem. The development and course of atherosclerotic processes associated with lipid and other metabolic changes are characterized by a long latent period, the clinical manifestation is often an acute vascular catastrophe, which can lead to human disability and death. Differences associated with sex are observed in the clinical course and manifestations, which raises the suspicion that gender influences processes related to atherosclerosis. Atherosclerotic cardiovascular disease (ACD) includes two main most dangerous clinical manifestations: IHD and cerebrovascular disease (mainly ischemic stroke). Other less common clinical manifestations of atherosclerosis include aortic atherosclerosis and peripheral vascular disease. Gender-related differences were also identified concerning these diseases. The present review discusses the effects of gender and age on atherosclerotic processes, disease development, and clinical manifestations. The metabolic basis for the development of atherosclerosis appears to be related to sex hormones. Thus this issue is interesting and useful for doctors of different specialties.

Nutrient Restriction In Utero Induces Remodeling of the Vascular Extracellular Matrix in Rat Offspring

The uterine environment may influence the development of chronic diseases later in life. The authors hypothesized that maternal nutritional restriction prenatally induces remodeling of offspring blood vessels such that they become stiff and contribute to the development of adult hypertension. To test this hypothesis, the authors studied the blood vessels of offspring of dams that were exposed to 50% maternal food restriction (MFR) from e10 to term as compared to age-matched controls. In aortas of MFR offspring, there was a significant increase in elastin and glycosaminoglycans (GAG) at 1 day of age. By 2 months of life, there was a significant increase in collagen and a decrease in GAG in MFR offspring aortas. A redistribution of elastin was also noted in MFR offspring, with a significant decrease in the interelastin laminae at both 1 day and 2 months. In mesenteric arterioles of MFR offspring, there was a decrease in GAG in 1-day-old and 2-month-old MFR offspring. There were no changes in elastin in both age groups in mesenteric arterioles, and by 2 months of life, collagen deposition was also found in these resistance vessels. There was a significant increase in expression of matrix metalloproteinase 9 (MMP-9) mRNA in 1-day-old MFR aortas, while both MMP-9 and MMP-2 expression was increased in the 4-month-old MFR aortas. These results indicate a significant remodeling of the extracellular matrix occurs in both conduit and resistance vessels. By 2 months of life, the compositions of both vessel types are consistent with stiff vessels, a contributing factor to hypertension.

The critical role of hemodynamics in the development of cerebral vascular disease

Atherosclerosis and intracranial saccular aneurysms predictably localize in areas with complex arterial geometries such as bifurcations and curvatures. These sites are characterized by unique hemodynamic conditions that possibly influence the risk for these disorders. One hemodynamic parameter in particular has emerged as a key regulator of vascular biology—wall shear stress (WSS). Variations in geometry can change the distribution and magnitude of WSS, thus influencing the risk for vascular disorders. Computer simulations conducted using patient-specific data have suggested that departures from normal levels of WSS lead to aneurysm formation and progression. In addition, multiple studies indicate that disturbed flow and low WSS predispose patients to extracranial atherosclerosis, and particularly to carotid artery disease. Conversely, in the case of intracranial atherosclerosis, more studies are needed to provide a firm link between hemodynamics and atherogenesis. The recognition of WSS as an important factor in cerebral vascular disease may help to identify individuals at risk and guide treatment options.

Reproductive factors and lower extremity arterial occlusive disease in women

BACKGROUND

Reproductive variables affecting sexual hormone levels seem to be significant for atherosclerosis, a major cause of morbidity of the vessels of the lower extremities such as lower extremity arterial occlusive disease (LEAOD). We quantify a direct relationship between reproductive variables including age at regular and premature menopause and the incidence of severe LEAOD among post-menopausal women.

METHODS AND RESULTS

Questionnaires were administered to 269 female amputees with LEAOD, 224 patients who underwent total joint replacement due to osteoarthritis and 88 healthy women. Respondents provided information on: age at menarche, age at the onset of menopause, number of births, number of abortions, lifetime oral contraceptive use, hysterectomy, oophorectomy, and medical consultation and treatment for post-menopausal symptoms. The in-sample log-odds ratio of LEAOD incidence was modeled as a function of the reproductive variables. An increase in the risk of LEAOD was associated with a reduction in the length of the fertile period, an increase in the number of births, and lifetime oral contraceptive use of 10 years or longer; a decrease in the risk of LEAOD was associated with an increase in the number of abortions.

CONCLUSION

We established a distinct relationship between reproductive variables, such as length of fertile period and age at menopause, and the development of severe LEAOD. The relations that we found are, by and large, consistent with other findings on similar ailments.

Estrogen reduces endothelial progenitor cell senescence through augmentation of telomerase activity

BACKGROUND

Recent studies have demonstrated that aging or senescence constitutes a potential limitation to the ability of endothelial progenitor cells (EPCs) to sustain ischemic tissue and repair. Conversely, estrogens have been shown to accelerate recovery of the endothelium after vascular injury.

OBJECTIVE

To investigate whether estrogens are able to prevent senescence of EPCs.

METHODS AND RESULTS

Human EPCs were isolated from peripheral blood and characterized. After ex-vivo cultivation, the cells became senescent as determined by acidic beta-galactosidase staining. 17beta-estradiol dose-dependently inhibited the onset of EPC senescence in culture. Because cellular senescence is critically influenced by telomerase, which elongates telomeres, we measured telomerase activity using a polymerase chain reaction (PCR)-enzyme-linked immunosorbent assay (ELISA) technique. 17beta-estradiol significantly increased telomerase activity. Interestingly, reverse transcriptase-PCR analysis demonstrated that 17beta-estradiol dose-dependently increased the catalytic subunit, telomerase reverse transcriptase (TERT) - an effect that was significantly inhibited by pharmacological phosphatidylinositol 3-kinase (PI3-K) blockers (either wortmannin or LY294002). Because the expression of TERT is regulated by the PI3-K/Akt pathway, we examined the effect of 17beta-estradiol on Akt activity in EPCs. Immunoblotting analysis revealed that 17beta-estradiol dose-dependently led to phosphorylation and, thus, to activation of Akt in EPCs. We also examined whether the protective effect of 17beta-estradiol on EPC senescence translates into the augmentation of mitogenic activity in EPCs. A [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenol)-2-(4-sulfophenyl)-2H-tetrazolium] (MTS) assay demonstrated that the mitogenic potential in EPCs treated with 17beta-estradiol exceeded that in untreated (control) EPCs (P < 0.01). In addition, EPCs released vascular endothelial growth factor (VEGF) protein--an effect that was significantly augmented by 17beta-estradiol. Finally, in a Matrigel assay, EPCs treated with both 17beta-estradiol and VEGF were shown to be more likely to integrate into the network formation than those treated with VEGF alone.

CONCLUSION

The inhibition of EPC senescence by estrogen in vitro may improve the functional activity of EPCs in a way that is important for potential cell therapy.

Assessment of the body mass index and selected physiological parameters in pre- and post-menopausal women

The main purpose of this paper is to describe the variability of the body mass index (BMI) and selected physiological parameters (serum glucose, total serum cholesterol, systolic and diastolic blood pressure) in women before and after menopause. The empirical basis for the assessment is the material obtained in cross-sectional studies carried out in the years 1998-2001 in a group of 2204 women aged 35-65 years, residents of the Wielkopolska region, Poland. The results indicate that hormonal changes taking place in the climacterium bring about an increase in the BMI. It was observed that women receiving Hormone Replacement Therapy in the perimenopause had BMI significantly lower than naturally menopausal women. Increased levels of total serum cholesterol and blood glucose were recorded. The trend has a stronger relation with the age of the subjects than with the character of the menopause. The systolic and diastolic blood pressure values were also found to increase significantly after the menopause, but no relationship with the type of menopause was found.

Determinants of the effect of estrogen on the progression of subclinical atherosclerosis: Estrogen in the Prevention of Atherosclerosis Trial

OBJECTIVE

To determine the extent to which the estrogen-induced changes in lipids and markers of carbohydrate metabolism explain the beneficial effect of estrogen therapy on the progression of carotid artery intima-media thickness (IMT) in postmenopausal women.

DESIGN

A randomized, double-blind, placebo-controlled, single-center trial enrolling 222 postmenopausal women 45 years and older without cardiovascular disease and with low-density lipoprotein (LDL) cholesterol levels of 3.37 mmol/L or greater (> or = 130 mg/dL). Intervention was unopposed micronized 17beta-estradiol versus placebo. Measurements were made using high-resolution B-mode ultrasonography to measure carotid artery IMT at baseline and every 6 months on-trial.

RESULTS

Progression of carotid IMT was inversely related to on-trial high-density lipoprotein (HDL) cholesterol (P = 0.04) and was directly related to on-trial LDL-cholesterol (P = 0.005). Compared with placebo, women randomized to estradiol showed a higher mean on-trial HDL-cholesterol level and a lower mean on-trial LDL-cholesterol level. In contrast, fasting glucose, insulin, and hemoglobin A1C were lowered and insulin sensitivity increased with estradiol therapy, but the changes were not related to carotid IMT progression. On-trial HDL-cholesterol and LDL-cholesterol were significant independent determinants of carotid IMT progression, jointly explaining 30% of the treatment effect of unopposed estrogen on the progression of carotid IMT.

CONCLUSION

Unopposed 17beta-estradiol reduced carotid IMT progression in postmenopausal women in part by increasing HDL-cholesterol and decreasing LDL-cholesterol. Although women randomized to estradiol showed improvement in all the markers of carbohydrate metabolism, these factors did not play a significant role in carotid IMT progression.

A dietary and exercise intervention slows menopause-associated progression of subclinical atherosclerosis as measured by intima-media thickness of the carotid arteries

OBJECTIVES

The object of this study was to assess the effects of menopause and a diet/exercise intervention on subclinical atherosclerosis progression.

BACKGROUND

Subclinical atherosclerosis has been linked to higher coronary heart disease and stroke rates and is greater among postmenopausal women according to cross-sectional analyses. Whether menopause is associated with an accelerated progression of subclinical disease is unknown, as is the extent to which lifestyle intervention can alter the course of progression.

METHODS

Intima-media thickness (IMT) measures of the common carotid artery (CCA), internal carotid artery (ICA), and bulb segments of the carotid arteries were measured twice during the course of 4 years in 353 women from the Women's Healthy Lifestyle Project, a dietary and exercise clinical trial designed to prevent adverse risk factor changes through the menopause. A third measure was obtained 2.5 years later for 113 women.

RESULTS

The progression of IMT was observed for the average of all segments (AVG), the CCA, and the bulb (0.007 mm/year, 0.008 mm/year, and 0.012 mm/year; p < 0.01 for all), but not for the ICA. Among controls, menopause was associated with accelerated IMT progression (0.003 mm/year for premenopausal women vs. 0.008 mm/year for perimenopausal/postmenopausal women for AVG IMT; p = 0.049). Additionally, among the 160 perimenopausal/postmenopausal women, the intervention slowed IMT progression (0.008 mm/year for the control group vs. 0.004 mm/year for the intervention group for AVG IMT; p = 0.02). Similar results were found for the CCA and bulb segments.

CONCLUSIONS

These data demonstrate that the menopause transition is associated with accelerated subclinical atherosclerosis progression and that a diet/exercise intervention slows menopause-related atherosclerosis progression.

Taurine prevents hypercholesterolemia in ovariectomized rats fed corn oil but not in those fed coconut oil

We studied whether the type of dietary fatty acid influences the preventive effect of taurine on the ovarian hormone deficiency-induced increase in plasma cholesterol concentration in 6-mo-old ovariectomized rats. Rats were fed one of the following four diets for 28 d: purified diets based on corn oil, which is rich in linoleic acid, with or with out taurine (50 g/kg) or purified diets based on coconut oil, which is rich in lauric and myristic acids, with or without taurine. Body mass gain, food intake, liver weight and plasma apolipoprotein (apo) A-I, apo B, LDL and VLDL concentrations were not affected by the diets. On the other hand, taurine lowered the plasma total cholesterol concentration (P < 0.02) in rats fed corn oil, but not in those fed coconut oil. In rats fed both types of oils, taurine increased the LDL receptor mRNA level (P < 0.01), hepatic cholesterol 7alpha-hydroxylase activity (P < 0.01) and fecal bile acid excretion (P < 0.01). Taurine increased the HMG-CoA reductase mRNA level (P < 0.02) in the liver of rats fed coconut oil, but not in those fed corn oil. Taurine increased liver total lipid (P < 0.05) and triglyceride (P < 0.05) concentrations in rats fed corn oil, but not in those fed coconut oil. These results indicate that the effect of taurine on ovarian hormone deficiency-induced changes in cholesterol metabolism is influenced by the type of dietary fatty acids.

17beta-estradiol inhibition of NADPH oxidase expression in human endothelial cells

We investigated the hypothesis that the antiatherosclerotic effect of 17beta-estradiol (E2) is due to a shift in the nitric oxide (NO)/superoxide (O2-) balance in the vessel wall, thereby increasing the bioavailability of NO. In human umbilical vein cultured endothelial cells, E2 (1-100 nmol/l), but not 17alpha-estradiol, caused a time- and concentration-dependent decrease in expression of the NADPH oxidase subunit gp91phox (up to 60% inhibition at both the mRNA and protein level). This effect was prevented by coincubation with the estrogen receptor antagonists tamoxifen and ICI 182,780 (1 micromol/l each). Within the same concentration range, E2 also up-regulated endothelial nitric oxide synthase expression ( approximately twofold). Moreover, preincubation of the cells with E2 or a gp91phox antisense oligonucleotide significantly decreased their capacity to generate O2- on phorbol ester stimulation (i.e., assembly of the active NADPH oxidase complex). Blockade of NO synthase activity, on the other hand, had no effect on phorbol ester-stimulated O2- formation. In addition, E2 (100 nmol/l) inhibited the increase in adhesion molecule and chemokine expression in cells exposed to cyclic strain. Cyclic strain enhanced endothelial O2- formation, thereby offsetting the inhibitory effect of NO on the expression of these gene products. E2 thus seems to act as an antioxidant at the genomic level which by improving the NO/O2- balance normalizes expression of proatherosclerotic gene products in endothelial cells.

The nature of the effect of female gonadal hormone replacement therapy on cognitive function in post-menopausal women: a meta-analysis

We reviewed epidemiological and experimental studies of female gonadal hormone replacement therapy (HRT) on cognitive function in post-menopausal women and carried out meta-analyses. In healthy ageing women, HRT has small and inconsistent effects that include enhancement of verbal memory, abstract reasoning and information processing. Epidemiological studies show larger effects than experimental studies, which is not related to sample size. Important confounds may be that women who start using HRT are healthier than women who do not. Also, controlling for socio-economic status diminishes the effect of HRT. The effects of HRT may depend on the age and type of menopause and the therapeutic intervention used, with the most widely used drug, Premarin, having least effect. However, the effects are independent of mood and climacteric symptom alleviation. There is a paucity of experimental studies that include healthy elderly women. The evidence for an estrogen deficiency in women with dementia and cognitive dysfunction is inconsistent. Nevertheless, epidemiological studies suggest that HRT protects against the development of clinically diagnosed Alzheimer's disease. However, poor recall of HRT use by patients and altered physician behaviour may have confounded the effects. Surprisingly, both healthy and demented women with low education seem to benefit most from HRT. Three recent controlled experimental studies using Premarin showed no effects of HRT in preventing further cognitive decline in women who already have Alzheimer's disease. Duration of treatment seems to play an important role, with beneficial effects declining-and even reversing-with longer treatment in women with Alzheimer's disease.Future research should further investigate the cognitive effect of different HRT preparations, serum estrogen levels, and the interactions of HRT with age, menopausal status and existing protective (e.g. education) and risk factors (e.g. smoking and apolipoprotein E genotype) for cognitive decline and Alzheimer's disease.

Lymphangioleiomyomatosis

Lymphangioleiomyomatosis (LAM), a rare disorder of unknown cause that occurs almost exclusively in women of childbearing years, is characterized microscopically by abnormal smooth muscle proliferation in the lung, lymphatics, and mediastinal, abdominal and lower cervical lymph nodes. LAM is associated with progressive dyspnea, recurrent pneumothoraces, chylous effusions, abdominal tumors (angiomyolipoma), and chylous ascites. Because of the predilection of this disease for young women, therapies to date have mainly involved hormonal manipulation. Although the efficacy of these therapies has not been established, the clinical course is more favorable in recent studies compared with earlier reports.

The effect of hormone replacement therapy on arterial distensibility and compliance in perimenopausal women: a 2-year randomised trial

A single centre randomised placebo-controlled trial was performed to assess the 2-year effects of hormone replacement therapy compared to placebo on mechanical arterial properties in 99 perimenopausal women recruited from the general population. The trial was double-blind with respect to a sequential combined regimen of oral 17beta-oestradiol and desogestrel (17betaE(2)-D) and the placebo group and open with respect to combination of conjugated equine oestrogens and norgestrel (CEE-N). At baseline, distensibility and compliance of the common carotid artery were measured non-invasively with B-mode ultrasound and a vessel wall movement detector system, and the distensibility coefficient (DC) and compliance coefficient (CC) were calculated. Measurements were repeated after 6 and 24 months. Change in DC and CC in treatment groups was compared to placebo. After 24 months, changes for 17betaE(2)-D compared to placebo were -1.4x10(-3)/kPa (95% CI -4.4; 1.7, P=0.39) for DC and 0. 26 mm(2)/kPa (95% CI -0.01; 0.53, P=0.07) for CC. Changes for CEE-N compared to placebo were 0.4x10(-3)/kPa (95% CI -1.0; 1.9, P=0.79) and 0.11 mm(2)/kPa (95% CI -0.14; 0.37, P=0.40). For systolic blood pressure (SBP), diastolic blood pressure (DBP) and arterial lumen diameter no changes were found. In this study no significant differences in changes in distensibility and compliance were found between perimenopausal women using 17betaE(2)-D or CEE-N and women using placebo after 6 and 24 months.

Behaviour of the carotid wall in menopausal women with and without arterial hypertension

OBJECTIVE

A study was conducted on the carotid vascular wall to evaluate its behaviour in postmenopausal women suffering from arterial hypertension compared to normotensive postmenopausal women.

METHOD

Intima-media thickness(IMT) of carotid artery was determined by ecoduplex scanner in 182 postmenopausal women (age range 40-60 years) divided in four age classes (40-45, 46-50, 51-55, 55-60 years). Ninety-one women presented normal arterial blood pressure (SBP 136.6+/-11.7 and DBP 82.3+/-8.9 mmHg) and 91 were hypertensive (SBP 172.6+/-11.7 and DBP 97.4+/-6.6 mmHg).

RESULTS

The normotensive women presented the following IMT values: 1.19+/-0.21 mm (40-45 years), 1.21+/-0.25 mm (46-50 years), 1.25+/-0.20 mm (51-55 years), 1.25+/-0.20 mm (55-60 years). IMT values in hypertensive women were: 1.75+/-0.25 mm (40-45 years), 1.77+/-0.30 mm (45-50 years), 1.91+/-0.28 mm (51-55 years), 2.02+/-0.33 mm (55-60 years). ANOVA test was performed in both groups of women and did not show any significant difference in the four age classes of normotensive women. On the other hand it revealed a statistical significance between 40-45 and 46-50-year-old hypertensive classes (P<0.001) and between 51-55 and 55-60-year-old hypertensive clases (P<0.02).

CONCLUSIONS

There was a correlation between age and IMT in the arterial hypertensives, especially in two older classes, and between the duration of menopause and IMT values. The results indicated that carotid wall thickening was constantly higher in hypertensive women compared with normotensive ones.

Effects of the menopause, gender, and estrogen replacement therapy on vascular nitric oxide activity

Changes in vascular nitric oxide (NO) activity may contribute to cardiovascular risk. We determined the effect of the menopause, gender, and estrogen replacement therapy on arterial vascular NO activity. Vascular NO activity and sensitivity were determined in 15 healthy premenopausal women (mean age, 48 yr), 12 postmenopausal women (51 yr), and 14 men (51 yr). The effects of 14 days of estrogen replacement therapy (625 microg conjugated estrogens) were studied in 20 healthy postmenopausal women (60 yr). Forearm blood flow responses to brachial arterial infusions of L-NG-monomethyl-arginine (L-NMMA), norepinephrine, glyceryl trinitrate (GTN), and serotonin were determined using venous occlusion plethysmography. Constrictor responses to L-NMMA were reduced in postmenopausal women (82 +/- 14, summary response, mean +/- SEM) and men (89 + 6) compared to premenopausal women (118 + 10; P < 0.05). Constrictor responses to norepinephrine were increased in males (125 +/- 13) compared to premenopausal (81 +/- 8) and postmenopausal (88 +/- 16) women (P < 0.05). No differences were observed in GTN or serotonin responsiveness. Constrictor responses to L-NMMA increased after estrogen replacement (132 +/- 7 vs. 89 +/- 14; P < 0.05), with no change in norepinephrine, GTN, or serotonin responses. The menopause and male gender were associated with reduced arterial NO activity. Two weeks of estrogen replacement therapy restored vascular NO activity to premenopausal levels. Changes in vascular NO activity may contribute to changes in cardiovascular risk associated with male gender, postmenopausal status, and estrogen replacement therapy. Increased alpha-adrenoceptor responsiveness may contribute to increased cardiovascular risk in males.

Serum lipids and lipoproteins and carotid artery wall intima-media thickness in a population of menopausal women

OBJECTIVE

To assess the influence of aging on serum lipids and lipoproteins in menopausal women and to determine whether arterial hypertension can determine carotid artery wall intima-media thickening in these subjects.

DESIGN

We assessed cholesterol, low density lipoprotein cholesterol, triglycerides, and carotid artery wall intima-media thickness in 729 menopausal women aged 40-65 years, divided into four age groups (40-45 years, 46-50 years, 51-55 years, and 56-60 years).

RESULTS

Serum lipids and lipoproteins rose progressively in the different age groups. Carotid wall thickness also increased and was more evident when accompanied by arterial hypertension.

CONCLUSIONS

Our results suggest that elevated serum lipids and lipoproteins are interrelated with increased carotid artery wall intima-media thickness. Moreover, they showed the benefits of hormone replacement therapy.

Estrogen-induced hepatic toxicity and hepatic cancer: differences between two closely related hamster species

AIMS/BACKGROUND

Estrogen is known to affect hepatobiliary function; however, it is unusual for high serum levels of estrogen to actually result in clinically detectable hyperbilirubinemia. Women affected by cholestatic jaundice during pregnancy share this genetic susceptibility with two Cricetulus hamsters, the Armenian hamster (Cricetulus migratorius) and the Chinese hamster (Cricetulus griseus). Nevertheless, the pathophysiologic process responsible for this estrogen induced icterus may be different in women and hamsters. The present study compares various facets of estrogen-induced icterus in these two closely related hamsters.

METHODS

Hamsters were injected with various estrogens and the acute and chronic effects on liver were monitored by measuring changes in serum constituents and by observing changes in hepatic structure as seen grossly and by light and electron microscopy.

RESULTS

In previous studies, hepatic tumors developed in most Armenian hamsters after chronic estrogen treatment, but in the present study, the livers of Chinese hamsters were remarkably free of neoplastic change under similar conditions. Also, when compared with the responses in the Armenian hamsters, signs of hepatic destruction and regeneration were less prevalent in estrogen-treated Chinese hamsters, and they were less susceptible to the effects of estrogen (because larger doses of estrogen were required to produce icterus and the bilirubin levels were lower and of shorter duration). In contrast to the findings in Armenian hamsters, bile canaliculi were severely affected in livers of estrogen-treated Chinese hamsters, and hepatic microvesicular steatosis, indicative of an unusual lipodystrophy caused by estrogen, was prominent. An additional lesion peculiar to the Chinese hamster was striking sinusoidal dilatation, which may be analogous to the oral contraceptive-induced sinusoidal dilatation in humans.

CONCLUSIONS

Although these two hamster species are genetically similar, the genes activated by the estrogen receptor show remarkable heterogeneity when their respective livers are examined. Comparisons within these species may provide information about the specific gene activation responsible for particular pathologic events.

Effects of different hormone replacement regimens on postmenopausal women with abnormal lipid levels. Menopause Study Group

OBJECTIVES

A retrospective, subset analysis of the prospective Menopause Study Group data was performed to determine the effects of four conjugated estrogens (CE) + medroxyprogesterone acetate (MPA) regimens and one unopposed CE regimen on the lipid profiles of women with abnormal lipid levels (n = 525). Previously unpublished data on the entire study population were also reviewed to determine the effects of these hormone replacement regimens on blood pressure and weight (n = 1368, 1374, respectively).

METHODS

During a 1-year, prospective trial, all patients took CE. Groups A and B also took continuous MPA 2.5 and 5 mg, respectively, C and D took MPA 5 and 10 mg for the last 14 cycle days of each 28-day cycle, and E took matching placebo tablets to replace MPA.

RESULTS

After 1 year, all five regimens were directly associated with significant elevations in high density lipoprotein-2 (HDL2) cholesterol and significant reductions in low density lipoprotein (LDL) cholesterol (p < 0.05), although unopposed estrogen produced the greatest increase in HDL2 cholesterol. The CE + MPA regimens were also associated with significant decreases in total cholesterol. Triglyceride levels did not change significantly from baseline in any treatment group (baseline values > 1.808 mmol/l (> 160 mg/dl)), although the CE + MPA regimens were associated with a mean triglyceride decrease and CE-only women (n = 8) had a mean triglyceride increase. No regimen produced significant weight or blood pressure changes.

CONCLUSIONS

This analysis suggests that hormone replacement therapy (CE + MPA), used in appropriate dosages, may alter the HDL2 cholesterol and LDL cholesterol lipoproteins in postmenopausal women with borderline lipid levels (a higher-risk population) in a cardioprotective manner.

Effects of Continuous and Cyclic Hormone Replacement Therapy on the Lipoprotein Profile in Postmenopausal Women

Objective:

To provide an overview of the information concerning cyclic and continuous hormone replacement therapy (HRT) and the effects of the various regimens on the lipid profile.

Data Sources:

MEDLINE (January 1966–December 1996) and Index Medicus (January 1995-December 1996) searches were conducted to identify relevant studies and review articles. Bibliographies of selected articles also were reviewed.

Study Selection:

Studies addressing continuous and cyclic use of a progesterone formulation along with daily conjugated equine estrogen (CEE) and their effects on the lipid profiles of postmenopausal women were selected for review.

Data Extraction:

Applicable data were selected and used in a review format.

Data Synthesis:

CEE has been shown to increase high-density-lipoprotein cholesterol, which may decrease the risk of cardiovascular heart disease. Medroxyprogesterone acetate (MPA) has been added to CEE for postmenopausal HRT to prevent endometrial hyperplasia and cancer. However, MPA negates the beneficial effects of CEE on the lipid profile. Many different HRT regimens, both continuous and cyclic, are being used to increase compliance and to decrease adverse effects. Which regimen offers the best lipid profile results is evaluated in this article.

Conclusions:

The lipid profile effects of HRT using continuous MPA are not significantly different from those obtained with cyclic MPA. Use of a continuous MPA regimen may also offer the long-term advantages of less vaginal bleeding and increased compliance.

Nikolaj Nikolajewitsch Anitschkow (1885-1964) established the cholesterol-fed rabbit as a model for atherosclerosis research

The cholesterol-fed rabbit is a widely used model for experimental atherosclerosis research. In regard to this, one name is periodically mentioned: Nikolaj Nikolajewitsch Anitschkow. Those infrequent reminders of an important name in modern medical history do not pay an adequate tribute to basic findings concerning the pathology and pathogenesis of atherosclerosis. In contrast to research groups at that time conducting experiments with protein enriched diets, Anitschkow demonstrated, in 1913 in St. Petersburg, that it was cholesterol only that caused these atherosclerotic changes in the rabbit arterial intima, which was very similar to human atherosclerosis. By analysing the plaque's development and histology, Anitschkow was able to identify the cell types, on which modern atherosclerosis research is now focussing with a new set of immunohistochemical methods: smooth muscle cells, macrophages and lymphocytes. He noted early (fatty streaks) and advanced (atheromatous plaques) lesions and, by standardizing cholesterol feeding, he discovered that the amount of cholesterol uptake was directly proportional to the degree of atherosclerosis formation. His explanation for this observation was what modern terminology calls 'response-to-injury'. With modern immunohistochemical and molecular-biological methods, the cholesterol-fed rabbit can be used to investigate the pathophysiological aspects which also contribute to human atherosclerosis, such as lipoproteins, diabetes, mitogens, growth-factors, adhesion molecules, endothelial-function, receptor-pathways or platelets. This model can be combined with a number of other methods causing endothelial dysfunction and injury, such as balloon denudation, electric stimulation, cuff implantation, artificial hypertension, diabetes or infection. Bred strains of hereditary hypercholesterolemic rabbits or those resistant to a cholesterol-diet provide further possibilities to expand experimental designs.

Impact of combined hormone replacement therapy on serum lipid metabolism: new aspects

The objective of this study was to evaluate the impact of combined estrogen-progestogen therapy on low density lipoprotein (LDL) particle size (determined by the LDL cholesterol/apolipoprotein B ratio). The prospective study was carried out on 139 healthy Danish early postmenopausal women. The subjects were randomized to placebo or to 2 mg estradiol valerate equivalents, either sequentially combined with 75 micrograms levonorgestrel, 10 mg medroxyprogesterone acetate (MPA), or 150 micrograms desogestrel, or continuously combined with 1 mg cyproterone acetate. LDL particle size was calculated before treatment and at nine-well-defined times during the subsequent 84 days. LDL particle size was reduced by all four treatments. This change was statistically significant for estradiol valerate combined with levonorgestrel and MPA (6.2 +/- 2.7% and 5.6 +/- 2.1% (mean +/- SEM), respectively; p < 0.05 for both, placebo-corrected). Estradiol valerate combined with MPA induced cyclic (progestogen-minus estrogen-related values) decreases (-6.3 +/- 2.6%; p < 0.05), and with levonorgestrel there were cyclic increases (5.1 +/- 2.7%; p = 0.067) in LDL particle size (placebo-corrected). In conclusion, combined estrogen-progestogen therapy causes a decrease in LDL particle size. A cyclic variation in LDL cholesterol/apolipoprotein B ratio was observed during sequential treatment.

Regulation of bradykinin B2-receptor expression by oestrogen

1. Tissue kallikrein is overexpressed in the kidney of female rats, this sexual dimorphism being associated with a greater effect of early blockade of bradykinin B2-receptors on female blood pressure phenotype. We evaluated the effect of ovariectomy and oestradiol benzoate (50 micrograms kg-1 every two days for two weeks) on the vasodepressor response to intra-arterial injection of bradykinin (150-900 ng kg-1) and on the expression of bradykinin B2-receptors. 2. Ovariectomy reduced the magnitude of the vasodepressor response to bradykinin and unmasked a secondary vasopressor effect. Oestrogen replacement restored the vasodepressor response to bradykinin in ovariectomized rats. 3. The vasodepressor responses to sodium nitroprusside (3-18 micrograms kg-1), acetylcholine (30-600 ng kg-1), desArg9-bradykinin (150-900 ng kg-1) or prostaglandin E2 (30-600 ng kg-1) were significantly reduced by ovariectomy. Oestrogen restored to normal the responses to desArg9-bradykinin, acetylcholine and prostaglandin E2, but not that to sodium nitroprusside. 4. B2-receptor mRNA levels were decreased by ovariectomy in the aorta and kidney and they were restored to normal levels by oestrogen. Neither ovariectomy nor oestradiol affected receptor expression in the heart and uterus. 5. These results indicate that oestrogen regulates B2-receptor gene expression and function. Since kinins exert a cardiovascular protective action, reduction in their vasodilator activity after menopause might contribute to the increased risk of pathological cardiovascular events. Conversely, the cardioprotective effects of oestrogen replacement might be, at least in part, mediated by activation of the kallikrein-kinin system.

The Postmenopausal Estrogen/Progestin Interventions Study: primary outcomes in adherent women

OBJECTIVE

To assess the efficacy of unopposed estrogen, and three estrogen/progestin regimens on selected heart disease risk factors among adherent women and to contrast those results with efficacy among all women in the PEPI study.

DESIGN

A 3-year, multicenter, randomized, double-blinded, placebo-controlled clinical trial.

PARTICIPANTS

A total of 847 healthy postmenopausal women aged 45 to 64 years of age with no known contraindication to hormone therapy, who attended their 36 month clinical visit.

INTERVENTION

Participants were randomized in equal numbers to one of the following treatments: (1) placebo; (2) conjugated equine estrogen (CEE) 0.625 mg daily; (3) CEE 0.625 daily plus medroxyprogesterone acetate (MPA) 10 mg, days 1-12; (4) CEE 0.625 daily plus MPA 2.5 mg daily; or (5) CEE 0.625 daily plus micronized progesterone (MP) 200 mg, days 1-12.

ANALYSIS

Analyses are based on adherent women, where adherence is defined as taking at least 80% of pills at each 6-month visit.

RESULTS

Adherence rates were high in all groups except women with a uterus assigned to unopposed CEE. The difference in HDL-C levels resulting from the CEE vs. CEE+MP was approximately three times larger than in the intent-to-treat analyses, reaching statistical significance (P < 0.05). In each active treatment, LDL-C decreased 10-15%. Triglycerides increased 15-20% in each opposed CEE arm and over 25% in the CEE only arm; this difference was not statistically significant. Fibrinogen increased by 7% among placebo adherers, but decreased or remained fairly stable among the active arm adherers. Systolic blood pressure increased 3-5% in all treatment arms. Women adherent to the CEE+MPA arms had twice the increase of 2 h glucose levels as women adherent to CEE only, or CEE+MP (8-9% vs. 3-4%). Two-hour insulin levels decreased 3-12% for all arms. The patterns of change for fibrinogen, SBP, 2 h glucose and insulin were similar to those from the intent-to-treat analyses.

CONCLUSIONS

In analyses limited to adherent women, all active treatments, compared to placebo, continued to have similar and favorable effects on LDL-cholesterol and fibrinogen and no significant effects on blood pressure or insulin levels. Given the overall high adherence rates in PEPI, the results are similar to the intent-to-treat analyses, as expected. Only the trend of HDL-C to have a larger increase in the CEE only arm (in the intent-to-treat analyses) gained statistical significance in analyses restricted to adherers.

Gender differences in the generation of superoxide anions in the rat aorta

Generation of superoxide anions was measured in the isolated aorta of female and male rats using a lucigenin chemiluminescence technique. Aortae from male rats produced significantly more O2- (about 34%) than the aortae from female animals. Removal of endothelium reduced generation of O2- in the aorta of male and female rats by 23.9 +/- 1.3 and 15.3 +/- 2.3 pmole O2- min-1 mg-1 dry weight (p < 0.05), respectively. The denuded aortae of both sexes showed no different O2- production. Generation of O2- could not be influenced by inhibition of cycloxygenase with indomethacin or xanthine oxidase with oxypurinol. In contrast to the generation of O2- under basal conditions, stimulated generation of O2- by either addition of phorbol 12-myristate 13-acetate (to stimulate protein kinase C) or diethylthiocarbamate (to inhibit vascular superoxide dismutase activity) showed no significant gender differences. It is concluded that the endothelium from male rats produces more O2- under basal conditions than the endothelium from female rats.

Treatment of skin aging with topical estrogens

BACKGROUND

The coincidence of climacteric symptoms and the beginning of skin aging suggests that estrogen deficiency may be a common and important factor in the perimenopausal woman. Often hormones have been considered important in endogenous aging of the skin, but their role has not been clearly defined. Therefore, we investigated, whether topical treatment of the skin with estrogen could reverse some of the changes in the aging skin.

MATERIAL AND METHODS

The effects of 0.01% estradiol and 0.3% estriol compounds were compared in 59 preclimacteric women with skim aging symptoms. Monthly determinations of estrodiol (E2), follicle-stimulating hormone (FSH), and prolactin (PRL) were done and the monthly clinical monitoring was supplemented by measurements of skin hydration by corneometry and profilometry. In 10 patients, skin biopsies were taken for immunohistochemical determination of collagen types I and III.

RESULTS

After treatment for 6 months, elasticity and firmness of the skin had markedly improved and the wrinkle depth and pore sizes had decreased by 61 to 100% in both groups. Furthermore, skin moisture had increased and the measurement of wrinkles using skin profilometry, revealed significant, or even highly significant, decreases of wrinkle depth in the estradiol and the estriol groups, respectively. On immunohistochemistry, significant increases of Type III collagen labeling were combined with increased numbers of collagen fibers at the end of the treatment period. As to hormone levels, only those of PRL had increased significantly and no systemic hormonal side effects were noted.

Postmenopausal hormone-replacement therapy and cardiovascular risk

Case-control and cohort studies support the hypothesis that postmenopausal oestrogen-replacement therapy reduces the risk of atherosclerotic disease manifestations. The evidence for a cardioprotective effect of such a therapy is, however, incomplete because randomized prospective studies are missing. Because it may be almost impossible to conduct placebo-controlled trials in the future, other study designs will be needed to minimize selection bias. Further work is required to define the optimal dose and administration schedule of oestrogen and to determine whether addition of progestogens alters the beneficial effect of oestrogen on the cardiovascular system. Such studies may also provide mechanistic insight into the interaction between lipoprotein metabolism and haemostasis and its relation to the atherosclerotic disease process.

Vascular responses to 17 beta-oestradiol in postmenopausal women

The vascular responses to 17 beta-oestradiol were examined in 23 postmenopausal women (59 +/- 7 years [mean +/- SD]) using a placebo-controlled double-blind crossover design. All women received 1 mg 17 beta-oestradiol or placebo (P) sublingually on consecutive days in random order. Axial diameters and blood flow rates of the left common femoral arteries were determined before and 60-80 min after application of verum or placebo as well as 10-30 min after 10 mg isosorbide dinitrate (ISDN) with a quantitative duplex ultrasound technique. Oestradiol induced a vasodilation of femoral arteries (+6.4 +/- 4.1% of basal, P < 0.001 vs. basal and P), the vessel diameter was unchanged with placebo (+0.7 +/- 2.1%). The blood flow rate increased significantly after oestradiol application (+30 +/- 28%, P < 0.05 vs. basal and P), but not after placebo (+11 +/- 21%). Mean blood pressure and heart rate remained constant with both drugs. Despite its vasodilatory effect, ISDN significantly reduced the arterial blood flow after pretreatment with oestradiol and placebo, probably through cardiac preload reduction. In conclusion, 17 beta-oestradiol alters the vascular tone of systemic arteries resulting in a vasodilation and increase of blood flow. We suggest that these direct vascular actions may contribute to the preventive properties of oestrogens on cardiovascular diseases in postmenopausal women.