Vasomotor symptom prevalence is associated with polymorphisms in sex steroid-metabolizing enzymes and receptors

Vascular actions of estrogens: functional implications

The impact of estrogen exposure in preventing or treating cardiovascular disease is controversial. But it is clear that estrogen has important effects on vascular physiology and pathophysiology, with potential therapeutic implications. Therefore, the goal of this review is to summarize, using an integrated approach, current knowledge of the vascular effects of estrogen, both in humans and in experimental animals. Aspects of estrogen synthesis and receptors, as well as general mechanisms of estrogenic action are reviewed with an emphasis on issues particularly relevant to the vascular system. Recent understanding of the impact of estrogen on mitochondrial function suggests that the longer lifespan of women compared with men may depend in part on the ability of estrogen to decrease production of reactive oxygen species in mitochondria. Mechanisms by which estrogen increases endothelial vasodilator function, promotes angiogenesis, and modulates autonomic function are summarized. Key aspects of the relevant pathophysiology of inflammation, atherosclerosis, stroke, migraine, and thrombosis are reviewed concerning current knowledge of estrogenic effects. A number of emerging concepts are addressed throughout. These include the importance of estrogenic formulation and route of administration and the impact of genetic polymorphisms, either in estrogen receptors or in enzymes responsible for estrogen metabolism, on responsiveness to hormone treatment. The importance of local metabolism of estrogenic precursors and the impact of timing for initiation of treatment and its duration are also considered. Although consensus opinions are emphasized, controversial views are presented to stimulate future research.

Genetic polymorphisms, hormone levels, and hot flashes in midlife women

OBJECTIVE

Hot flashes disrupt the lives of millions of women each year. Although hot flashes are a public health concern, little is known about risk factors that predispose women to hot flashes. Thus, the objective of this study was to examine whether sex steroid hormone levels and genetic polymorphisms in hormone biosynthesis and degradation enzymes are associated with the risk of hot flashes.

METHODS

In a cross-sectional study design, midlife women aged 45-54 years (n=639) were recruited from Baltimore and its surrounding counties. Participants completed a questionnaire and donated a blood sample for steroid hormone analysis and genotyping. The associations between genetic polymorphisms and hormone levels, as well as the associations between genetic polymorphisms, hormone levels, and hot flashes were examined using statistical models.

RESULTS

A polymorphism in CYP1B1 was associated with lower dehydroepiandrosterone-sulfate (DHEA-S) and progesterone levels, while a polymorphism in CYP19 (aromatase) was associated with higher testosterone and DHEA-S levels. Lower progesterone and sex hormone binding globulin levels, lower free estradiol index, and a higher ratio of total androgens to total estrogens were associated with the experiencing of hot flashes. A polymorphism in CYP1B1 and a polymorphism in 3betaHSD were both associated with hot flashes.

CONCLUSION

Some genetic polymorphisms may be associated with altered levels of hormones in midlife women. Further, selected genetic polymorphisms and altered hormone levels may be associated with the risk of hot flashes in midlife women.

Bioidentical Hormone Therapy: A Review of the Evidence

Bioidentical hormone therapy (BHT) uses bioidentical hormones (BHs), derivatives of plant extracts chemically modified to be structurally indistinguishable from human endogenous hormones. BHTs are available commercially or can be compounded into different dosages and for different routes of administration. Typically, compounded preparations of BHs may include estriol, estrone, estradiol, testosterone, micronized progesterone, and occasionally dehydroepiandrosterone (DHEA). It is generally accepted that estrogen-based hormone therapies share similar efficacies as well as risks. Many FDA-approved and regulated pharmaceutically manufactured and branded conventional hormone therapies (CHTs) employ BHs. Since the publication of the Women's Health Initiative (WHI) trial results publicizing an increased risk of stroke, venous thrombosis, and breast cancer and no beneficial effect on coronary heart disease (CHD), use of CHT has declined, and there has been increased interest in alternative approaches. This review of the literature related to compounded BHT and the practices of its advocates is to determine if sufficient scientific evidence supports claims of greater efficacy and safety and any additional risks and uncertainties not generally associated with CHTs. Compounded BHTs have been promoted by some as natural, safer, and in some cases more efficacious than conventional hormone therapies, but there is a dearth of scientific evidence to support these claims. Compounded BHTs lack well controlled studies examining route of administration, pharmacokinetics, safety, and a critical, science-based rationale for the mixture and ratios of bioidentical estrogens employed in many preparations. Many advocates of compounded BHTs customize prescriptions based on saliva tests or blood sera levels in direct contradiction to evidence-based guidelines, which support tailoring HT individually according to symptoms. Currently, scientific uncertainties associated with compounded BHTs make their use less preferable to that of CHTs, as CHTs have been and continue to be assessed by clinical trials regarding both benefits and risks and are indicated for use according to evidence-based guidelines.

Sex steroid hormone pathway genes and health-related measures in women of 4 races/ethnicities: the Study of Women's Health Across the Nation (SWAN)

We synthesized findings relating health outcomes and genetic variants of the sex steroid hormone pathway in women from the Study of Women's Health Across the Nation (SWAN) Genetics Study. The SWAN Genetics Study, a component of the longitudinal SWAN study, describes selected genetics characteristics of health-related attributes during the menopausal transition in African American, Caucasian, Chinese, and Japanese women. At baseline, SWAN recruited menstruating women aged 42 to 52 years, who were not using exogenous hormones. Immortalized cell lines were developed and genotyped in 1,538 specimens from 1,757 participants in the genetics study. Genotypes and haplotypes from 6 genes (27 single nucleotide polymorphisms [SNPs]) in the sex steroid hormone pathway were related to circulating hormone concentrations, menstrual cycle profiles, and health-related outcomes, including lipids, diabetes mellitus, depressive symptoms, measures of cognition, bone mineral density (BMD), and vasomotor symptoms. Allele frequencies and distances differed substantially in the 4 race/ethnicity-specific groups evaluated, leading to variable patterns of association with health-related measures. For example, 17HSD genotypes were highly associated with diabetes risk in Caucasian women, whereas its haplotypes were associated with diabetes risk in both African American and Caucasian women. Several SNPs were associated with multiple outcomes. ESR1 rs3798577 was significantly associated with circulating estradiol concentrations, indicators of ovarian aging, high-density lipoprotein (HDL) cholesterol, apolipoprotein A-1, insulin sensitivity, and lumbar spine BMD. CYP1A1 rs2606345 was related to estrogen metabolite concentrations, vasomotor symptoms, and depressive symptoms. Some associations were much more prominent in specific races/ethnicities; Chinese women had statistically significant relations between ESR2 rs1256030 and HDL cholesterol, lumbar spine BMD, hip BMD, and metabolic syndrome. Importantly, women in the SWAN Genetics Study were typical of women in the community-based SWAN sample. This community-based sample of women from the SWAN Genetics Study identified important genetic sex steroid hormone pathway variants in relation to measures of health status. The magnitude and breadth of these relationships should motivate further research to verify and extend the findings.