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Oestrogens and atherosclerotic vascular disease--lipid factors
Insights
Postmenopausal estrogen replacement therapy significantly reduces cardiovascular disease risk by favorably altering lipoproteins. While progestogens can antagonize these effects, estrogen therapy remains beneficial for managing hyperlipidemia and preventing atherosclerosis in postmenopausal women.
Area of Science:
- Cardiovascular Science
- Endocrinology
- Lipid Metabolism
Background:
- Cardiovascular disease is the leading cause of death for postmenopausal women.
- Epidemiological studies suggest estrogen replacement therapy (ERT) reduces cardiovascular disease risk by approximately 50%.
Purpose of the Study:
- To review the effects of postmenopausal ERT on cardiovascular disease risk factors, particularly lipoproteins.
- To examine the influence of different ERT formulations and progestogen co-administration on lipid profiles and atherosclerosis.
Main Methods:
- Review of epidemiological studies and clinical trials on postmenopausal ERT.
- Analysis of estrogen's impact on plasma lipoproteins (LDL, HDL, triglycerides) and arterial wall metabolism.
- Evaluation of the role of progestogens in modulating ERT's cardiovascular benefits.
Main Results:
- ERT favorably influences LDL and HDL cholesterol concentrations and lipoprotein metabolism in the arterial wall, impeding atherosclerotic plaque formation.
- Oral estrogens show greater benefits on LDL and HDL cholesterol but increase triglycerides compared to transdermal routes.
- Progestogens can antagonize estrogen's beneficial effects on lipoproteins, though net benefits may persist with low-dose cyclical use.
Conclusions:
- Estrogen therapy can be beneficial for managing hyperlipidemia and secondary prevention of atherosclerosis in postmenopausal women.
- Understanding the interplay between estrogens, progestogens, and lipoproteins is crucial for optimizing ERT regimens.
- Despite potential adverse effects on lipoprotein profiles, ERT demonstrates significant cardiovascular protective potential.
Abstract:
Cardiovascular disease remains the major cause of death for postmenopausal women in Western societies. The majority of epidemiological studies indicate that postmenopausal oestrogen replacement therapy is associated with a 50% reduction in the risk of cardiovascular disease, with much of the reduction being mediated by changes in the plasma concentration of cholesterol within high and low density lipoproteins. In addition to favourably influencing the plasma concentration of lipoproteins, oestrogens also influence the complex metabolism of lipoproteins in the arterial wall, helping to impede the formation of the atherosclerotic plaque. Whilst oestrogens alter endothelial function, vascular reactivity and fibrinolysis, these changes are also seen with reduction of LDL cholesterol and may partly reflect the altered concentration of plasma lipoproteins induced by oestrogens. Oral oestrogens have substantially greater favourable effects on LDL and HDL cholesterol than their transdermal counterparts but also result in greater hypertriglyceridaemia. Most progestogens antagonize the beneficial effects of oestrogens on lipoproteins in a dose-dependent manner; however, cyclical use of low doses of progestogens with an oral oestrogen generally retains a net beneficial effect. Lipoprotein levels fluctuate during cyclical therapy, the most adverse changes being noted at the end of the progestogen phase. Lipoprotein concentrations are constant during continuous combined regimens which have the potential for more prolonged exposure to an adverse progestational effect. Despite adverse effects on the lipoprotein profile, animal studies suggest that progestogens do not substantially reverse the beneficial effects of oestrogens on the development of atherosclerosis. Finally, oestrogen therapy may be useful in the management of postmenopausal women with hyperlipidaemia, and also in the secondary prevention of clinical sequelae in women with established atherosclerosis.