Medroxyprogesterone acetate and dihydrotestosterone induce coronary hyperreactivity in intact male rhesus monkeys

Testosterone induces hyporesponsiveness by interfering with IP3 receptors in guinea pig airway smooth muscle

Asthma symptoms have been associated with sex steroids. During childhood, this illness seems more frequent in boys than in girls and this tendency reverts in puberty when it is more severe in women. Testosterone (TES), at supraphysiological concentrations, relaxed pre-contracted airway smooth muscle, but its effects at physiological concentrations have not been thoroughly studied. We explored this possibility in guinea pig tracheal smooth muscle. In myocytes TES (10 nM) abolished carbachol (CCh)-induced intracellular Ca²⁺ concentration ([Ca²⁺]i) increment. Ca²⁺ responses to ATP were partially modified by TES while histamine's were not. These results indicate that inositol 1,4,5-trisphosphate (IP₃) signaling pathway might be involved. Photolysis of caged-IP₃ increased [Ca²⁺]i and TES abolished this effect. TES diminished reactivity of the smooth muscle to CCh and this effect was non-genomic since it was unchanged by flutamide. In tracheal smooth muscle, mRNA for each IP₃ receptor (ITPR) isoform was found and, by immunofluorescence, ITPR1 and ITPR3 seems to be the main isoforms observed while ITPR2 was less prominent. Comparing the amino acid sequence of ITPR1 and the sequence of the TES binding site on the androgen receptor, we found that they share a short sequence. This domain could be responsible for the TES binding to the ITPR1 and probably for its blocking effect. We conclude that TES modifies ITPR1 function in airway smooth muscle, turning this tissue less reactive to contractile agonists that act through PLCβ-IP₃ signaling cascade. These results might be related to the low asthma prevalence in males from puberty to adulthood.

Reprint of "Use of medroxyprogesterone acetate for hormone therapy in postmenopausal women: Is it safe?"

Medroxyprogesterone acetate (MPA) has been in clinical use for over 30 years, and was generally considered to be safe until the results of long-term studies of postmenopausal hormone therapy (HT) using treatment with conjugated equine estrogens (CEE) combined with MPA and CEE alone suggested that MPA, and perhaps other progestogens, may play a role in the increased risk of breast cancer and cardiovascular diseases. This review examines critically the safety of MPA in terms of breast cancer and cardiovascular disease risk, and its effects on brain function. Research into mechanisms by which MPA might cause adverse effects in these areas, combined with the available clinical evidence, suggests a small increase in relative risk for breast cancer and stroke, and a decline in cognitive function, in older women using MPA with an estrogen for postmenopausal HT. However, short-term (less than 5 years) use of MPA with an estrogen in the years immediately after the onset of menopause for the management of vasomotor symptoms does not appear to be associated with any increased risk of these disorders.

The role of hormones and aromatase inhibitors on breast tumor growth and general health in a postmenopausal mouse model

BACKGROUND

Breast cancer is the most frequently diagnosed cancer in women in the United States. Approximately 70% of breast cancers are diagnosed in postmenopausal women. Major clinical trials and experimental studies showed that aromatase inhibitors are effective against postmenopausal breast cancer. Despite their effectiveness in reducing tumor recurrence, aromatase inhibitors have adverse effects on the cardiovascular system and increase osteoporosis and bone fractures. Our study is aimed at investigating the role of natural steroid hormones on serum cardiovascular and bone resorption markers in an established mouse model mimicking postmenopausal breast cancer.

METHODS

Ovariectomized nude mice were transplanted with MCF-7 breast cancer cells constitutively expressing aromatase. The mice were treated with different combinations and doses of steroids, [estrogen (25 pg, 40 pg, 100 pg), progesterone (6 ng) and testosterone (50 ng)] along with dehydroepiandrostenedione (100 ug). Serum levels of HDL, LDL/VLDL, free and total cholesterol, total and bone specific alkaline phosphatase and triglycerides were analyzed after 5, 10 and 15 months.

RESULTS

Free cholesterol and LDL/VLDL levels in serum were reduced in groups mimicking estrous cycle and menstrual cycle hormones treatment. HDL cholesterol was increased in all the hormone treated groups except the estrous cycle-mimicking group. Bone specific alkaline phosphatase was decreased in menstrual cycle levels of estrogen and progesterone treatment.

CONCLUSIONS

All together our results show that use of natural hormones in appropriate combinations have beneficial effects on cardiac and bone toxicity, along with better tumor reduction than current treatments.

Use of medroxyprogesterone acetate for hormone therapy in postmenopausal women: is it safe?

Medroxyprogesterone acetate (MPA) has been in clinical use for over 30 years, and was generally considered to be safe until the results of long-term studies of postmenopausal hormone therapy (HT) using treatment with conjugated equine estrogens (CEE) combined with MPA and CEE alone suggested that MPA, and perhaps other progestogens, may play a role in the increased risk of breast cancer and cardiovascular diseases. This review examines critically the safety of MPA in terms of breast cancer and cardiovascular disease risk, and its effects on brain function. Research into mechanisms by which MPA might cause adverse effects in these areas, combined with the available clinical evidence, suggests a small increase in relative risk for breast cancer and stroke, and a decline in cognitive function, in older women using MPA with an estrogen for postmenopausal HT. However, short-term (less than 5 years) use of MPA with an estrogen in the years immediately after the onset of menopause for the management of vasomotor symptoms does not appear to be associated with any increased risk of these disorders.

[Acquired long QT syndrome and cardiac arrest after general anesthesia. Case report and review of literature]

A 30-year-old woman, with no medical history, is operated on for breast implants. In recovery room, an episode of torsade de pointes occurs, progressing to ventricular fibrillation. The ECG after cardiopulmonary resuscitation and conversion to a normal sinus rhythm shows a corrected QT interval prolongation, whereas it is normalized after 48hours. We hypothesize that a ventricular fibrillation occurred after a torsade de pointes, due to drug-induced long QT syndrome during general anesthesia, with probably drug interaction.

Progestogens used in postmenopausal hormone therapy: differences in their pharmacological properties, intracellular actions, and clinical effects

The safety of progestogens as a class has come under increased scrutiny after the publication of data from the Women's Health Initiative trial, particularly with respect to breast cancer and cardiovascular disease risk, despite the fact that only one progestogen, medroxyprogesterone acetate, was used in this study. Inconsistency in nomenclature has also caused confusion between synthetic progestogens, defined here by the term progestin, and natural progesterone. Although all progestogens by definition have progestational activity, they also have a divergent range of other properties that can translate to very different clinical effects. Endometrial protection is the primary reason for prescribing a progestogen concomitantly with postmenopausal estrogen therapy in women with a uterus, but several progestogens are known to have a range of other potentially beneficial effects, for example on the nervous and cardiovascular systems. Because women remain suspicious of the progestogen component of postmenopausal hormone therapy in the light of the Women's Health Initiative trial, practitioners should not ignore the potential benefits to their patients of some progestogens by considering them to be a single pharmacological class. There is a lack of understanding of the differences between progestins and progesterone and between individual progestins differing in their effects on the cardiovascular and nervous systems, the breast, and bone. This review elucidates the differences between the substantial number of individual progestogens employed in postmenopausal hormone therapy, including both progestins and progesterone. We conclude that these differences in chemical structure, metabolism, pharmacokinetics, affinity, potency, and efficacy via steroid receptors, intracellular action, and biological and clinical effects confirm the absence of a class effect of progestogens.

Hormone replacement therapy in the geriatric patient: current state of the evidence and questions for the future. Estrogen, progesterone, testosterone, and thyroid hormone augmentation in geriatric clinical practice: part 1

This article presents an up-to-date review of the literature on hormone augmentation in the elderly to help primary care physicians better evaluate and utilize hormone replacement and optimization strategies to benefit their patients. The scientific literature suggests that hormone supplementation with estrogen, progesterone, testosterone, growth hormone, and thyroid hormone has the potential to improve quality of life and to prevent, or reverse, the many symptoms and conditions associated with aging, including fatigue, depression, weight gain,frailty, osteoporosis, loss of libido, and heart disease. Possible long-term side effects are also considered.

Systemic administration of AAV8-α-galactosidase A induces humoral tolerance in nonhuman primates despite low hepatic expression

In mice, liver-restricted expression of lysosomal enzymes from adeno-associated viral serotype 8 (AAV8) vectors results in reduced antibodies to the expressed proteins. To ask whether this result might translate to patients, nonhuman primates (NHPs) were injected systemically with AAV8 encoding α-galactosidase A (α-gal). As in mice, sustained expression in monkeys attenuated antibody responses to α-gal. However, this effect was not robust, and sustained α-gal levels were 1-2 logs lower than those achieved in male mice at the same vector dose. Because our mouse studies had shown that antibody levels were directly related to expression levels, several strategies were evaluated to increase expression in monkeys. Unlike mice, expression in monkeys did not respond to androgens. Local delivery to the liver, immune suppression, a self-complementary vector and pharmacologic approaches similarly failed to increase expression. While equivalent vector copies reached mouse and primate liver and there were no apparent differences in vector form, methylation or deamination, transgene expression was limited at the mRNA level in monkeys. These results suggest that compared to mice, transcription from an AAV8 vector in monkeys can be significantly reduced. They also suggest some current limits on achieving clinically useful antibody reduction and therapeutic benefit for lysosomal storage diseases using a systemic AAV8-based approach.

Progestogen effects at vascular level: the endothelial cells

Progesterone and progestogens are active molecules on the cardiovascular system. However, their action is not as well-characterized as the effects of estrogens. Data of the last clinical trials suggest the possibility of harmful cardiovascular effects of progestogens, and the debate on the role of progesterone and progestins on the vascular wall is open. From an experimental point of view, each progestogen presents typical effects on the cardiovascular system and their administration results in diverse modifications of the effects of estrogens, sometimes acting synergically, others being neutral or antagonizing effects of estrogens. In this paper, we review the most important data from in vivo and in vitro studies which have been published on the effects of progesterone and progestogens on vascular cells. Endothelium is a target tissue for sex steroids and progesterone is able to regulate endothelial cell function and morphology. Even if the perfect molecule does not exist, the understanding of the molecular basis of each progestogen in vascular tissue is therefore of paramount importance for the most appropriate use with an optimal cardiovascular profile.

Contraceptive hormone use and cardiovascular disease

Contraceptive hormones, most commonly prescribed as oral contraceptives (OCs), are a widely utilized method to prevent ovulation, implantation, and, therefore, pregnancy. The Women's Health Initiative demonstrated cardiovascular risk linked to menopausal hormone therapy among women without pre-existing cardiovascular disease, prompting a review of the safety, efficacy, and side effects of other forms of hormone therapy. A variety of basic science, animal, and human data suggests that contraceptive hormones have antiatheromatous effects; however, relatively less is known regarding the impact on atherosclerosis, thrombosis, vasomotion, and arrhythmogenesis. Newer generation OC formulations in use indicate no increased myocardial infarction risk for current users, but a persistent increased risk of venous thromboembolism. There are no cardiovascular data available for the newest generation contraceptive hormone formulations, including those that contain newer progestins that lower blood pressure, as well as the nonoral routes (transdermal and vaginal). Current guidelines indicate that, as with all medication, contraceptive hormones should be selected and initiated by weighing risks and benefits for the individual patient. Women 35 years and older should be assessed for cardiovascular risk factors including hypertension, smoking, diabetes, nephropathy, and other vascular diseases, including migraines, prior to use. Existing data are mixed with regard to possible protection from OCs for atherosclerosis and cardiovascular events; longer-term cardiovascular follow-up of menopausal women with regard to prior OC use, including subgroup information regarding adequacy of ovulatory cycling, the presence of hyperandrogenic conditions, and the presence of prothrombotic genetic disorders is needed to address this important issue.

Male hormonal contraception: concept proven, product in sight?

Current male hormonal contraceptive (MHC) regimens act at various levels within the hypothalamic pituitary testicular axis, principally to induce the withdrawal of the pituitary gonadotrophins and in turn intratesticular androgen production and spermatogenesis. Azoospermia or severe oligozoospermia result from the inhibition of spermatogonial maturation and sperm release (spermiation). All regimens include an androgen to maintain virilization, while in many the suppression of gonadotrophins/spermatogenesis is augmented by the addition of another anti-gonadotrophic agent (progestin, GnRH antagonist). The suppression of sperm concentration to 1 x 10(6)/ml appears to provide comparable contraceptive efficacy to female hormonal methods, but the confidence intervals around these estimates remain relatively large, reflecting the limited number of exposure years reported. Also, inconsistencies in the rapidity and depth of spermatogenic suppression, potential for secondary escape of sperm into the ejaculate and onset of fertility return not readily explainable by analysis of subject serum hormone levels, germ cell number or intratesticular steroidogenesis, are apparent. As such, a better understanding of the endocrine and genetic regulation of spermatogenesis is necessary and may allow for new treatment paradigms. The development of an effective, consumer-friendly male contraceptive remains challenging, as it requires strong translational cooperation not only between basic scientists and clinicians but also between public and private sectors. At present, a prototype MHC product using a long-acting injectable testosterone and depot progestin is well advanced.

An overlooked connection: serotonergic mediation of estrogen-related physiology and pathology

BACKGROUND

In humans, serotonin has typically been investigated as a neurotransmitter. However, serotonin also functions as a hormone across animal phyla, including those lacking an organized central nervous system. This hormonal action allows serotonin to have physiological consequences in systems outside the central nervous system. Fluctuations in estrogen levels over the lifespan and during ovarian cycles cause predictable changes in serotonin systems in female mammals.

DISCUSSION

We hypothesize that some of the physiological effects attributed to estrogen may be a consequence of estrogen-related changes in serotonin efficacy and receptor distribution. Here, we integrate data from endocrinology, molecular biology, neuroscience, and epidemiology to propose that serotonin may mediate the effects of estrogen. In the central nervous system, estrogen influences pain transmission, headache, dizziness, nausea, and depression, all of which are known to be a consequence of serotonergic signaling. Outside of the central nervous system, estrogen produces changes in bone density, vascular function, and immune cell self-recognition and activation that are consistent with serotonin's effects. For breast cancer risk, our hypothesis predicts heretofore unexplained observations of the opposing effects of obesity pre- and post-menopause and the increase following treatment with hormone replacement therapy using medroxyprogesterone.

SUMMARY

Serotonergic mediation of estrogen has important clinical implications and warrants further evaluation.

Metabolite ligands of estrogen receptor-beta reduce primate coronary hyperreactivity

Previous reports showed that 17beta-estradiol implants attenuate in vivo coronary hyperreactivity (CH), characterized by long-duration vasoconstrictions (in coronary angiographic experiments), in menopausal rhesus monkeys. Prolonged Ca2+ contraction signals that correspond with CH in coronary vascular muscle cells (VMC) to the same dual-constrictor stimulus, serotonin + the thromboxane analog U-46619, in estrogen-deprived VMC were suppressed by >72 h in 17beta-estradiol. The purpose of this study was to test whether an endogenous estrogen metabolite with estrogen receptor-beta (ER-beta) binding activity, estriol (E3), suppresses in vivo and in vitro CH. E3 treatment in vivo for 4 wk significantly attenuated the angiographically evaluated vasoconstrictor response to intracoronary serotonin + U-46619 challenge. In vitro treatment of rhesus coronary VMC for >72 h with nanomolar E3 attenuated late Ca2+ signals. This reduction of late Ca2+ signals also appeared after >72 h of treatment with subnanomolar 5alpha-androstane-3beta,17beta-diol (3beta-Adiol), an endogenous dihydrotestosterone metabolite with ER-beta binding activity. R,R-tetrahydrochrysene, a selective ER-beta antagonist, significantly blocked the E3- and 3beta-Adiol-mediated attenuation of late Ca2+ signal increases. ER-beta and thromboxane-prostanoid receptor (TPR) were coexpressed in coronary arteries and aorta. In vivo E3 treatment attenuated aortic TPR expression. Furthermore, in vitro treatment with E3 or 3beta-Adiol downregulated TPR expression in VMC, which was blocked for both agonists by pretreatment with R,R-tetrahydrochrysene. E3- and 3beta-Adiol-mediated reduction in persistent Ca2+ signals is associated with ER-beta-mediated attenuation of TPR expression and may partly explain estrogen benefits in coronary vascular muscle.