Hemodynamic effects of transdermal estradiol alone and combined with norethisterone acetate

Low-dose estrogen therapy for prevention of osteoporosis: working our way back to monotherapy

The risks of low bone mineral density, osteoporosis and fractures, are major concerns in postmenopausal women. Although postmenopausal hormone therapy is effective for reducing these risks, safety issues have been raised by the results of studies such as the Women's Health Initiative. Although there are scientifically valid reasons to be wary of the general applicability of the Women's Health Initiative findings, the study has underscored the continuing need for research into new forms of menopausal hormone therapy. Low-dose transdermal estrogen monotherapy can preserve bone density while relieving vasomotor symptoms. Transdermal administration may offer advantages, including lack of first-pass liver metabolism, which permits the use of lower doses and avoids a negative impact on the lipid profile. Moreover, a recently published 2-year study of ultra-low-dose transdermal estrogen monotherapy in an older population similar to that of the WHI reported significant increases in bone mineral density, accompanied by significant reductions in markers of bone turnover, with no increased risk of endometrial hyperplasia or other side effects. Additional studies are warranted to shed further light on the possible benefits of low-dose estrogen monotherapy for the prevention of bone loss in postmenopausal women.

Vasodilating effect of norethisterone and its 5 alpha metabolites: a novel nongenomic action

Estrogens are generally administered in hormone replacement therapy in combination with synthetic progestins. Studies of cardiovascular risk factors in postmenopausal women have shown a variety of responses according to the molecular structure of the progestin used in hormone replacement therapy schemes. The present study sets out to determine the vasoactive effects of norethisterone and its 5alpha-dihydro (5alpha-norethisterone) and -tetrahydro (3alpha,5alpha-norethisterone and 3beta,5alpha-norethisterone) metabolites in isolated precontracted rat thoracic aorta. The addition of norethisterone and 3alpha,5alpha-norethisterone in rat aorta exhibited a potent, concentration-response inhibition of noradrenaline-induced contraction, while 5alpha- and 3beta,5alpha-norethisterone had very little, if any, vasorelaxing effect. Relaxation to norethisterone and 3alpha,5alpha-norethisterone had very rapid time-courses and it was neither affected by the absence of endothelium nor by the inhibitor of nitric oxide synthase, Nomega-nitro-L-arginine methyl ester (L-NAME). The addition of specific anti-androgen, anti-progestin and anti-estrogen compounds and protein synthesis inhibitors did not preclude the vasorelaxing effect of norethisterone and its 3alpha,5alpha-reduced metabolite. The results strongly suggest that these effects are not mediated by nuclear sex steroid hormone receptors. The overall data document a novel nongenomic endothelium-independent vasorelaxing action of a 19-nor synthetic progestin and one of its A-ring-reduced derivatives.

The use of hormone replacement therapy in postmenopausal women with type 2 diabetes

In healthy postmenopausal women, estrogen or hormone replacement therapy (ERT or HRT) can alleviate menopausal symptoms and prevent osteoporosis and may also protect against cardiovascular disease (CVD). In addition to improving lipid metabolism, there are reports that estrogen also improves parameters regulating carbohydrate metabolism, including insulin resistance, in healthy women. Therefore, it is likely that ERT or HRT would also benefit women with type 2 diabetes, not only in relieving menopausal symptoms but also in improving the metabolic abnormalities associated with diabetes and in preventing cardiovascular disease.

The pharmacokinetics and efficacy of different estrogens are not equivalent

In the next decade many women will turn to the medical community for advice on maintaining or improving health after menopause. Estrogen replacement therapy, with or without progestins, alleviates menopausal symptoms, prevents or manages osteoporosis, and reduces the increased cardiovascular disease risk that results from estrogen deficiency caused by ovarian decline. Although several estrogen replacement products are available, the pharmacokinetics and efficacy of these products may vary depending on either the estrogen formulation or the route of administration, or both. For example, oral estrogens, which elicit a marked hepatic response, induce greater beneficial effects on serum lipoproteins than transdermal estrogens, which circumvent first-pass liver metabolism. Oral conjugated estrogens and transdermal estradiol increase bone density and prevent bone loss. This article summarizes the studies comparing estrogen formulations and discusses the differential effects of various estrogen products that promote postmenopausal health.

Effect of medroxyprogesterone acetate and norethisterone on serum-stimulated and estradiol-inhibited proliferation of human coronary artery smooth muscle cells

OBJECTIVE

The addition of progestogen to estrogen replacement therapy is thought to antagonize, at least in part, the beneficial effects of estrogens on the vasculature. The aim of this study was to investigate the effect of two progestogens mostly used in clinical practice on the proliferation of vascular smooth muscle cells, which has been demonstrated to be a crucial step in the development of atherosclerosis.

MATERIAL AND METHODS

The effect of medroxyprogesterone acetate (MPA) and norethisterone (NET), which represent the two different classes of C21- and C19-progestogens, respectively, was investigated on proliferation of smooth muscle cells from human coronary artery in vitro. The steroids were tested in the concentration range 10(-8) to 10(-5) M, which is in the upper range of that reached during hormonal replacement therapy, and compared with control values.

RESULTS

Estradiol significantly inhibited serum-stimulated cell growth at the concentrations 10(-6) and 10(-5) M by 18% and 34%, respectively. MPA significantly enhanced serum-stimulated growth at the concentrations 10(-6) and 10(-5) M by 29% and 47%, respectively. In equimolar combinations of MPA and estradiol, proliferation of the cells was significantly stimulated at the concentrations 10(-6) and 10(-5) M by 26% and 44%, respectively. In contrast, NET had no significant effect on serum-stimulated cell growth and had no impact on the estradiol-inhibited proliferation.

CONCLUSIONS

These data suggest that MPA may antagonize beneficial antiatherosclerotic estradiol effects on the vasculature, whereas NET may be neutral in this respect. However, these effects occurred at supraphysiological concentrations. Because these concentrations might be reached in the target tissues, the clinical relevance for treatment of patients with cardiovascular risk cannot be excluded.

17beta-estradiol prevents oxidative stress and decreases blood pressure in ovariectomized rats

In this study, we tested whether estrogen deficiency is associated with oxidative stress and decreased nitric oxide (NO) production, which could be responsible for an increased blood pressure in ovariectomized rats. Hemodynamic studies were performed on conscious, chronically instrumented rats. Chronic estrogen replacement on ovariectomized rats lowered blood pressure approximately 13 mmHg, from 119 +/- 3 mmHg in ovariectomized rats to 106 +/- 3 mmHg in ovariectomized-treated rats; it was also accompanied by an increase in cardiac index and vascular conductance, achieving hemodynamic values similar to those shown by sham-operated rats. N(G)-nitro-L-arginine methyl ester administration lowered significantly less the vascular conductance (0.14 +/- 0.01 vs. 0.22 +/- 0.03 and 0.26 +/- 0.01 ml. min(-1). mmHg(-1)/100 g; P < 0.05) in ovariectomized rats than in the sham-operated and estrogen-treated ovariectomized rats, respectively. Estrogen replacement prevented the lower plasma levels of nitrites/nitrates observed in ovariectomized rats. The lower plasma total antioxidant status and reduced thiol groups and the increase in plasma lipoperoxides presented in ovariectomized animals were reestablished with the estrogen treatment. These results show that estrogen administration decreases blood pressure and increases vascular conductance in ovariectomized rats. This effect may be related to an increase in NO synthesis and/or preventing oxidative stress, then improving endothelial function.

Effect of age on the exercise response in normal postmenopausal women during estrogen replacement therapy

Postmenopausal estrogen replacement therapy (ERT) has been associated with a reduced risk of coronary artery disease (CAD). Whether this apparent cardioprotective effect is mediated by a cardiovascular benefit during exercise, however, has not been clearly defined. To evaluate rest and exercise variables with and without ERT, a randomized crossover trial was conducted in 23 postmenopausal women, ranging in age from 44 to 75 years, mean age 57+/-8 years. The rest and exercise variables were compared on ERT and during a drug-free period. The baseline measure was compared to the effects after 4 weeks of ERT and after 4 drug-free weeks. Echocardiographic treadmill exercise variables of heart rate (HR), blood pressure, rate-pressure product (RPP), and cardiac dimensions were determined at baseline and at the end of each treatment period. In response to ERT, there was a decrease in low-density lipoprotein (LDL) cholesterol (drug-free: 142+/-40 mg/dl, ERT: 124+/-34 mg/dl) and an increase in high-density lipoprotein (HDL) cholesterol (drug-free: 52+/-14 mg/dl, ERT: 62+/-15 mg/dl, both p<0.01). At rest, the study population had no overall significant change in HR, blood pressure, RPP, or left ventricular end-systolic and end-diastolic diameters when ERT was compared to the drug-free period. However, subjects with the fastest baseline resting HR had the greatest decrease in HR with ERT relative to the drug-free period (p<0.05). During exercise, ERT effected no change in peak HR, blood pressure, or RPP, although end-systolic diameter decreased slightly (p<0.05). With ERT, subject age correlated negatively with systolic blood pressure (p<0.05) and RPP (p<0.01); both blood pressure and RPP decreased in older subjects. In conclusion, ERT has differential effects dependent on baseline HR and age.

Chronic estrogen treatment increases levels of endothelial nitric oxide synthase protein in rat cerebral microvessels

BACKGROUND AND PURPOSE

A number of studies indicate that the female gonadal hormone, estrogen, confers protection against cerebrovascular disorders such as stroke. One postulated mechanism for these effects of estrogen is an action on the enzyme endothelial nitric oxide synthase (eNOS), which produces the vasodilatory molecule NO. We have investigated the hypothesis that estrogen increases expression of eNOS in cerebral microvessels of male and female rats.

METHODS

We measured levels of eNOS protein by Western blot in cerebral microvessels isolated from 7 groups of animals: females, ovariectomized females, ovariectomized females treated with estrogen, males, castrated males, castrated males treated with estrogen, and castrated males treated with testosterone.

RESULTS

Ovariectomized female rats treated with estrogen had 17. 4-fold greater levels of eNOS protein in cerebral microvessels than ovariectomized females, and intact females had 16.6-fold greater levels than ovariectomized females (P<0.01). In intact females, cerebral microvessel eNOS protein levels were 9.2-fold higher than those of intact males (P<0.05). Levels of eNOS protein in castrated males, castrated males treated with testosterone, and males were not different from each other. Estrogen treatment of castrated animals resulted in an 18.8-fold increase in cerebral microvessel eNOS protein (P<0.05).

CONCLUSIONS

Chronic estrogen treatment increases levels of eNOS protein in cerebral microvessels of male and female rats. This increase in eNOS protein correlates with our previous functional findings indicating that estrogen exposure increases NO modulation of cerebrovascular reactivity in both male and female animals. Upregulation of eNOS expression may contribute to the neuroprotective effect of estrogen.

Wellness in women after 40 years of age: the role of sex hormones and pheromones

In the past twenty years hundreds of peer-reviewed studies have provided a significant body of information to guide the health care of women in the second halves of their lives. The harmonic nature of the fertile reproductive system forms the background against which hormonal replacement therapy can be understood to best serve women. In addition, the 1986 discovery of human pheromones and the subsequent 1998 confirmation of their existence increases certain sexual options for maturing women. Not all hormonal replacement therapies and wellness regimens serve women well. Some regimens have the potential to produce disease, especially over-the-counter remedies like dehydroepiandrosterone and the formulas that contain estrogen. Some regimens profoundly improve the quality of life of many women; some women do not need or want such regimens. All sex hormones affect physiologic systems including the cardiovascular system, bone metabolism, cognitive function, sexual response, and sexual attractiveness. The 7 years before menopause have recently been revealed to be an extremely complex era. During this period, some women increase their estrogen levels to new lifetime highs; others start an unequivocal decline, and still others vary from month to month. Coupled to this variability in estrogen is an equally variable set of changes in progesterone secretion by the ovary as androgen secretion patterns also change. Many women show increases in circulating androgens while many others show deficiencies. Both the adrenal and the ovarian sources of these hormones show age-related changes that alter a woman's capacity to attract sexual attention through both her physical appearance (and condition) and her pheromonal excretions. The complex contributions to the overall health of a woman may not always be understood. Often a hysterectomy can exacerbate--rather than ameliorate--the conditions that led to the surgery. One in 2 American women is offered a hysterectomy, a rate 5 times higher than that of the European countries for which data are available. Ninety percent of hysterectomies are not related to cancer; they are elective procedures. Avoidance of elective hysterectomy helps prevent its side effects: sexual deficits, acceleration of cardiovascular and bone disease, and more rapid aging. No efficacy data exist that suggest that elective hysterectomy works better than the alternative approaches that do not induce these side effects. The health and well-being of women who have already had hysterectomies, with or without ovariectomies, can be improved by a recognition of the cascade of difficulties that must addressed. Estrogen, progesterone, and androgens all tend to be compromised by hysterectomy; all should be considered for replacement. Because hormonal regimens can be prescribed to enhance the quality of life, the review of the available research can allow the medical art to greatly benefit mature women. Not surprisingly, the emerging conclusion reveals that structurally human hormones, prescribed appropriately, almost always best serve the patient.