Sex steroid hormones exert biphasic effects on cytosolic magnesium ions in cerebral vascular smooth muscle cells: possible relationships to migraine frequency in premenstrual syndromes and stroke incidence

Progesterone Changes the Pregnancy-Induced Adaptation of Cardiomyocyte Kv2.1 Channels via MicroRNA-29b

The cardiovascular system adaptation occurs during pregnancy to ensure adequate maternal circulation. Progesterone (P4) is widely used in hormone therapy to support pregnancy, but little is known about its effects on maternal cardiac function. In this study, we investigated the cardiac repolarization and ion channel expression in pregnant subjects and mice models and studied the effects of P4 administrations on these pregnancy-mediated adaptations. P4 administrations shortened the prolongation of QTC intervals and action potential duration (APD) that occurred during pregnancy, which was mainly attributable to the reduction in the voltage-gated potassium (Kv) current under basal conditions. In vitro studies indicated that P4 regulated the Kv2.1 channel in a bidirectional manner. At a low dose (1 μM), P4 induced upregulation of Kv2.1 through P4 receptor, while at a higher dose (5 μM), P4 downregulated Kv2.1 by targeting microRNA-29b (miR-29b). Our data showed that P4 modulated maternal cardiac repolarization by regulating Kv2.1 channel activity during pregnancy. Kv2.1, as well as miR-29b, might be used as potential therapeutic targets for adaptations of the maternal cardiovascular system or evaluation of progesterone medication during pregnancy.

Migraine and reproductive life

Migraine is prevalent in women during the fertile age. Indeed, both neuroendocrine events related to reproductive stages (menarche, pregnancy, and menopause) and menstrual cyclicity and the use of exogenous sex hormones, such as hormonal contraception and replacement therapy, may cause significant changes in the clinical pattern of migraine. Menstrual migraine may be more severe, long-lasting, and refractory to both acute and prophylactic treatment and, therefore, requires tailored strategies. The use of headache diaries, which makes it possible to record prospectively the characteristics of every attack, is of paramount importance for evaluating the time pattern of headache and for identifying a clear link with menstrual cycle-related features. Estrogen variations are highly implicated in modulating the threshold to challenges by altering neuronal excitability, cerebral vasoactivity, pain sensitivity, and neuroendocrine axes throughout the menstrual cycle and not only at the time of menstruation. On the other hand, estrogen withdrawal may really constitute a triggering factor for migraine in women with peculiar characteristics of vulnerability with menstruation or following the discontinuation of exogenous estrogen, as happens with hormonal contraception during the fertile age or with hormone therapy at menopause. In addition, exogenous estrogen may contribute to the occurrence of neurological symptoms, such as aura. When aura occurs, hormonal treatment should be discontinued.

Classical estrogen receptors and ERα splice variants in the mouse

Estrogens exert a variety of effects in both reproductive and non-reproductive tissues. With the discovery of ERα splice variants, prior assumptions concerning tissue-specific estrogen signaling need to be re-evaluated. Accordingly, we sought to determine the expression of the classical estrogen receptors and ERα splice variants across reproductive and non-reproductive tissues of male and female mice. Western blotting revealed that the full-length ERα66 was mainly present in female reproductive tissues but was also found in non-reproductive tissues at lower levels. ERα46 was most highly expressed in the heart of both sexes. ERα36 was highly expressed in the kidneys and liver of female mice but not in the kidneys of males. ERβ was most abundant in non-reproductive tissues and in the ovaries. Because the kidney has been reported to be the most estrogenic non-reproductive organ, we sought to elucidate ER renal expression and localization. Immunofluorescence studies revealed ERα66 in the vasculature and the glomerulus. It was also found in the brush border of the proximal tubule and in the cortical collecting duct of female mice. ERα36 was evident in mesangial cells and tubular epithelial cells of both sexes, as well as podocytes of females but not males. ERβ was found primarily in the podocytes in female mice but was also present in the mesangial cells in both sexes. Within the renal cortex, ERα46 and ERα36 were mainly located in the membrane fraction although they were also present in the cytosolic fraction. Given the variability of expression patterns demonstrated herein, identification of the specific estrogen receptors expressed in a tissue is necessary for interpreting estrogenic effects. As this study revealed expression of the ERα splice variants at multiple sites within the kidney, further studies are warranted in order to elucidate the contribution of these receptors to renal estrogen responsiveness.

Sex-specific risk of cardiovascular disease and cognitive decline: pregnancy and menopause

Understanding the biology of sex differences is integral to personalized medicine. Cardiovascular disease and cognitive decline are two related conditions, with distinct sex differences in morbidity and clinical manifestations, response to treatments, and mortality. Although mortality from all-cause cardiovascular diseases has declined in women over the past five years, due in part to increased educational campaigns regarding the recognition of symptoms and application of treatment guidelines, the mortality in women still exceeds that of men. The physiological basis for these differences requires further research, with particular attention to two physiological conditions which are unique to women and associated with hormonal changes: pregnancy and menopause. Both conditions have the potential to impact life-long cardiovascular risk, including cerebrovascular function and cognition in women. This review draws on epidemiological, translational, clinical, and basic science studies to assess the impact of hypertensive pregnancy disorders on cardiovascular disease and cognitive function later in life, and examines the effects of post-menopausal hormone treatments on cardiovascular risk and cognition in midlife women. We suggest that hypertensive pregnancy disorders and menopause activate vascular components, i.e., vascular endothelium and blood elements, including platelets and leukocytes, to release cell-membrane derived microvesicles that are potential mediators of changes in cerebral blood flow, and may ultimately affect cognition in women as they age. Research into specific sex differences for these disease processes with attention to an individual's sex chromosomal complement and hormonal status is important and timely.

Hormesis and Female Sex Hormones

Hormone replacement after menopause has in recent years been the subject of intense scientific debate and public interest and has sparked intense research efforts into the biological effects of estrogens and progestagens. However, there are reasons to believe that the doses used and plasma concentrations produced in a large number of studies casts doubt on important aspects of their validity. The concept of hormesis states that a substance can have diametrically different effects depending on the concentration. Even though estrogens and progestagens have proven prone to this kind of dose-response relation in a multitude of studies, the phenomenon remains clearly underappreciated as exemplified by the fact that it is common practice to only use one hormone dose in animal experiments. If care is not taken to adjust the concentrations of estrogens and progestagens to relevant biological conditions, the significance of the results may be questionable. Our aim is to review examples of female sexual steroids demonstrating bidirectional dose-response relations and to discuss this in the perspective of hormesis. Some examples are highlighted in detail, including the effects on cerebral ischemia, inflammation, cardiovascular diseases and anxiety. Hopefully, better understanding of the hormesis phenomenon may result in improved future designs of studies of female sexual steroids.

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.

Recognition and treatment of menstrual migraine

BACKGROUND

Menstrual migraine is a chronic disorder affecting approximately 12.6 million women in the United States. In spite of its widespread prevalence, menstrual migraine often goes undiagnosed.

REVIEW SUMMARY

Characteristics of menstrual migraine, which include functional disability, increased headache severity, and lack of aura, are often overlooked, and therefore menstrual migraine is often underdiagnosed. Use of a 3-month diary to record migraine patterns can reveal the predictable patterns associated with menstrual migraine, and a diary is demonstrated to be a useful tool in diagnosis. Optimal treatment of menstrual migraine takes advantage of the predictability of the disorder. Treatment alternatives for menstrual migraine include acute therapy and short- or long-term preventive therapies. Acute therapy is given shortly after the migraine begins. Short-term preventive therapies are effective when administered during the time that menstrual migraine is most likely to occur; the treatment window is typically 2 days prior up to 3 days after the onset of menstruation. Providing triptans, nonsteroidal anti-inflammatory drugs, or estrogen supplements (gel or patches) during this window has been demonstrated to provide effective protection during the days when patients are at greatest risk for menstrual migraine. Alternatively, long-term preventive therapy may be required for recurrent headaches in patients with concomitant medical conditions for whom migraine therapy could serve a dual purpose.

CONCLUSION

By recognizing the patterns associated with menstrual migraine, prompt, acute, or preventive therapy can be used to effectively manage the disorder and reduce its related disability.

Potential role of female sex hormones in the pathophysiology of migraine

Clinical evidence indicates that female sex steroids may contribute to the high prevalence of migraine in women, as well as changes in the frequency or severity of migraine attacks that are in tandem with various reproductive milestones in women's life. While female sex steroids do not seem to be involved in the pathogenesis of migraine per se, they may modulate several mediators and/or receptor systems via both genomic and non-genomic mechanisms; these actions may be perpetuated at the central nervous system, as well as at the peripheral (neuro)vascular level. For example, female sex steroids have been shown to enhance: (i) neuronal excitability by elevating Ca(2+) and decreasing Mg(2+) concentrations, an action that may occur with other mechanisms triggering migraine; (ii) the synthesis and release of nitric oxide (NO) and neuropeptides, such as calcitonin gene-related peptide CGRP, a mechanism that reinforces vasodilatation and activates trigeminal sensory afferents with a subsequent stimulation of pain centres; and (iii) the function of receptors mediating vasodilatation, while the responses of receptors inducing vasoconstriction are attenuated. The serotonergic, adrenergic and gamma-aminobutyric acid (GABA)-ergic systems are also modulated by sex steroids, albeit to a varying degree and with potentially contrasting effects on migraine outcome. Taken together, female sex steroids seem to be involved in an array of components implicated in migraine pathogenesis. Future studies will further delineate the extent and the clinical relevance of each of these mechanisms, and will thus expand the knowledge on the femininity of migraine.

Ovarian Hormones and Migraine Headache: Understanding Mechanisms and Pathogenesis-Part 2

Migraine headache is strongly influenced by reproductive events that occur throughout the lifespan of women. Each of these reproductive events has a different "hormonal milieu," which might modulate the clinical course of migraine headache. Estrogen and progesterone can be preventative or provocative for migraine headache under different circumstances depending on their absolute serum levels, constancy of exposure, and types of estrogen/progesterone derivatives. Attacks of migraine with and without aura respond differently to changes in ovarian hormones. Clearly a greater knowledge of ovarian hormones and their effect on migraine is essential to a greater understanding of the mechanisms and pathogenesis of migraine headache.

Benefits and risks of sex hormone replacement in postmenopausal women

Because cardiovascular disease (CVD), which is far less common in young women than in men, but increases in prevalence in the postmenopausal years to that of men, estrogen repletion therapy (ERT) or combined hormone replacement therapy (HRT), has been widely used to protect against development of both CVD and osteoporosis, and possibly to delay or prevent cognitive loss or Alzheimer's disease (AD). To test the validity of favorable findings in many small-scale studies, and in clinical practice, a large-scale trial: the Women's Health Initiative (WHI) was undertaken by the National Institutes of Health (NIH), a trial that was prematurely ended because of increased CVD complications, despite some lessening of hip fractures. This paper suggests that the customary high intake of calcium (Ca)-advised to protect against osteoporosis, and the marginal magnesium (Mg) intake in the USA, might well be contributory to the adverse CV effects, that were all thromboembolic in nature. The procoagulant effect of estrogen is intensified by Ca; Mg-which counteracts many steps in the coagulation cascade and inhibits platelet aggregation and adhesion-is commonly consumed in sub-optimal amounts. The high American dietary Ca/Mg ratio might also be contributory to the WHI failure to confirm ERT's favorable mental effects. Discussed are mechanisms by which Mg enhances estrogen's central nervous system protective effects. Mg's improvement of cerebral blood flow, which improves brain metabolism, can also enhance removal of the beta amyloid peptide, accumulation of which is implicated in AD.

Menstrual migraine: A review of prophylactic therapies

Menstrual migraine is commonly encountered in women who are experiencing attacks of migraine without aura. It remains controversial whether attacks of menstrually associated migraine are more severe and have a longer duration than non-menstrually associated attacks. The pathogenesis of menstrual migraine is not understood completely, but it may be related to estrogen withdrawal or prostaglandin release. Preventative therapies may be considered in those who have failed abortive medications or have attacks lasting longer than 2 days. They can be administered short-term during the perimenstrual time period or continuously throughout the menstrual cycle. Short-term prophylactics should be tried first because menstrual migraines generally last for 1 to 4 days only. Continuous prophylactics may be considered in those with attacks refractory to short-term therapies.

Serum ionized magnesium levels and serum ionized calcium/ionized magnesium ratios in women with menstrual migraine

OBJECTIVE

It has been suggested that magnesium deficiency may play an important role in menstrual migraine and that the serum ionized calcium (ICa2+)/ionized magnesium (IMg2+) ratio is important in migraine headache. Studies were designed to test these hypotheses.

DESIGN

We prospectively evaluated 270 women seen at a headache clinic and in 61 women with menstrual migraine measured IMg2+, total magnesium, and ICa2+ levels so as to calculate the ICa2+/IMg2+ ratio.

RESULTS

The incidences of IMg2+ deficiency were 45% during menstrual attacks, 15% during nonmenstrual attacks, 14% during menstruation without a migraine, and 15% between menstruations and between migraine attacks. The serum ICa2+ levels were within our reference range, but the ICa2+/IMg2+ ratio was elevated (P<.01) in menstrual migraine.

CONCLUSIONS

The high incidence of IMg2+ deficiency and the elevated ICa2+/IMg2+ ratio during menstrual migraine confirm previous suggestions of a possible role for magnesium deficiency in the development of menstrual migraine.