Loss Of Estradiol Research Articles

Abstract P232: Estradiol Supplementation Prevents Ovariectomy-Induced Arterial Stiffness and Vascular Fibrosis

Background: Arterial stiffness is an independent predictor of cardiovascular events and mortality. Clinical data shows arterial stiffness increases rapidly after menopause, but mechanisms that mediate this change are not well known. The effect of ovariectomy (ovx) in rodent models is inconsistent in the literature. We hypothesize that the loss of estradiol (E2) contributes to ovx-induced arterial stiffening in a mouse model via fibrotic mechanisms, and that restoration of E2 will prevent these changes. Methods: Eight-week-old female C57/Bl6J mice received bilateral ovx or sham operation. Subcutaneous placebo or E2 (0.36 mg/day) pellets were implanted 2 weeks later to achieve three groups (sham+placebo, ovx+placebo, and ovx+E2). Aortic pulse wave velocity (PWV) was measured as an index of arterial stiffness. Blood pressure (BP) was measured by radiotelemetry. Aortic fibrosis was assessed by histological quantification of Masson’s trichrome staining and expressed as fold change in %fibrosis from sham. Pro-fibrotic genes were assessed in aortic tissue via quantitative PCR. Data presented are mean ± SEM. Results: Successful ovx was confirmed by reduction in uterine weight in the ovx group compared with other groups ( p <0.0001). At 6-weeks-post-surgery (N=16-18/group), PWV was increased in ovx (5.2±0.2 mm/ms) versus sham (3.4±0.1 mm/ms, p <0.0001) and ovx+E2 (3.5±0.1 mm/ms, p <0.0001) groups. In biweekly measures (N=4-5/group), PWV was greater in the ovx group at 4- and 6-weeks-post-surgery compared with sham ( p <0.0001) and ovx+E2 ( p <0.0001) groups, while PWV in the ovx+E2 group did not differ from sham at any time ( p ≥0.6). At 6-weeks post-surgery (N=5/group), there were no observed differences between groups for dark or light cycle systolic or diastolic BP, mean arterial pressure, or pulse pressure. Aortic fibrosis was increased in the ovx group (1.6-fold) compared with sham ( p =0.03) and ovx+E2 (0.9-fold, p =0.02) groups (N=10-12/group). Aortic fibrosis correlated with PWV at 6-weeks-post-surgery (R 2 =0.25, p <0.01). Aortic mRNA expression of collagen1a1 was increased in ovx versus ovx+E2 mice ( p =0.04, N=4-6/group). Conclusion: In conclusion, the restoration of E2 prevents ovx-driven arterial stiffening in female mice via a reduction in fibrotic remodeling of the aorta. The results also support that ovx is an appropriate model to study the mechanisms of menopause-induced arterial stiffening and that anti-fibrotic therapeutics may be beneficial in aging women.

The Loss of Estradiol by Androgen Deprivation in Prostate Cancer Patients Shows the Importance of Estrogens in Males.

The role of estradiol (E2; an estrogen) in men needs to be more appreciated. In this review, we address the clinical situations that allow the study of the clinical consequences of E2 deficiency in men and discuss the effects of restoration of levels of this reproductive steroid hormone. In men with advanced prostate cancer (PCa) undergoing androgen deprivation therapy (ADT), E2 is suppressed along with testosterone, leading to side effects affecting the quality of life. These include hot flashes, arthralgia, fatigue, mood changes, cognition problems, weight gain, bone loss, and increased risk of cardiovascular disease. Transdermal E2 alone for ADT has shown equivalent testosterone suppression compared to gonadotropin-releasing hormone (GnRH) agonists while also preventing estrogen-deficiency side effects, including hot flashes and bone loss. Co-treatment of ADT with fetal estrogen estetrol (E4) has shown significant improvements of estrogen-deficiency symptoms. These observations emphasize the need to raise awareness of the importance of estrogens in men among clinicians and the lay public.

Brown adipose tissue metabolism in women is dependent on ovarian status.

In rodents, loss of estradiol (E2) reduces brown adipose tissue (BAT) metabolic activity. Whether E2 impacts BAT activity in women is not known. BAT oxidative metabolism was measured in premenopausal (n = 27; 35 ± 9 yr; body mass index = 26.0 ± 5.3 kg/m2) and postmenopausal (n = 25; 51 ± 8 yr; body mass index = 28.0 ± 5.0 kg/m2) women at room temperature and during acute cold exposure using [11C]acetate with positron emission tomography coupled with computed tomograph. BAT glucose uptake was also measured during acute cold exposure using 2-deoxy-2-[18F]fluoro-d-glucose. To isolate the effects of ovarian hormones from biological aging, measurements were repeated in a subset of premenopausal women (n = 8; 40 ± 4 yr; BMI = 28.0 ± 7.2 kg/m2) after 6 mo of gonadotropin-releasing hormone agonist therapy to suppress ovarian hormones. At room temperature, there was no difference in BAT oxidative metabolism between premenopausal (0.56 ± 0.31 min-1) and postmenopausal women (0.63 ± 0.28 min-1). During cold exposure, BAT oxidative metabolism (1.28 ± 0.85 vs. 0.91 ± 0.63 min-1, P = 0.03) and net BAT glucose uptake (84.4 ± 82.5 vs. 29.7 ± 31.4 nmol·g-1·min-1, P < 0.01) were higher in premenopausal than postmenopausal women. In premenopausal women who underwent gonadotropin-releasing hormone agonist, cold-stimulated BAT oxidative metabolism was reduced to a similar level (from 1.36 ± 0.66 min-1 to 0.91 ± 0.41 min-1) to that observed in postmenopausal women (0.91 ± 0.63 min-1). These results provide the first evidence in humans that reproductive hormones are associated with BAT oxidative metabolism and suggest that BAT may be a target to attenuate age-related reduction in energy expenditure and maintain metabolic health in postmenopausal women.NEW & NOTEWORTHY In rodents, loss of estrogen reduces brown adipose tissue (BAT) activity. Whether this is true in humans is not known. We found that BAT oxidative metabolism and glucose uptake were lower in postmenopausal compared to premenopausal women. In premenopausal women who underwent ovarian suppression to reduce circulating estrogen, BAT oxidative metabolism was reduced to postmenopausal levels. Thus the loss of ovarian function in women leads to a reduction in BAT metabolic activity independent of age.

Abstract WP244: Increased Cardiac Fibrosis In Aged Female Mice May Increase The Risk Of Atrial Arrhythmogenesis And Stroke

Introduction: Atrial fibrillation (AF) is an arrhythmia that leads to intracardiac clot formation and cardioembolic strokes. Female sex is an independent risk factor for AF related stroke. This is reflected in the CHA 2 DS 2 -VASc score which is used to stratify AF patients with high, intermediate and low risk of embolism; female sex is an automatic point. The underlying etiology for this sexual dichotomy is unclear. Our laboratory has demonstrated sex differences in atrial tachycardia in aged wild type mice. It is now increasingly recognized that atrial substrate remodeling may lead to increased arrhythmogenesis. We hypothesized that aged females have increased atrial fibrosis leading to enhanced conduction abnormalities and atrial arrhythmias. Methods: C57BL6/J wild type aged 20-24 months old male and female mice underwent Echocardiogram (using vevo 3100 imaging system) to measure cardiac output, ejection fraction, stroke volume and left atrial diameter. All mice were sacrificed and cardiac tissue was used for immunohistochemistry. Cardiac sections were stained with masson trichrome stain and Image J was used for quantification of fibrosis. Data was analyzed using two sample t-test on GraphPad PRISM. Results: On Echocardiogram, we found no significant difference in cardiac output, ejection fraction and stroke volume in aged male and female mice, p&gt;0.5. We also measured the left atrial diameter in aged male (4.5 ± 0.2mm, n=4) and female mice (3.9± 0.2mm, n=6) and found no significant differences, p&gt;0.05. This demonstrates no baseline cardiac function abnormalities in aged males and females. On masson trichrome staining of the cardiac tissue, there was increased cardiac fibrosis in aged females, fibrotic area 2.3±0.19, n=3, as compared to males, 0.74±0.03, n=8/gp, p=0.02. Conclusion: Our results indicate that aged females have increased cardiac fibrosis as compared to aged males, despite having similar and normal cardiac function on echocardiogram. This fibrosis/ atrial substrate remodeling may lead to conduction abnormalities and arrhythmias in aged females. Ongoing studies in our laboratory are evaluating the role of aging and loss of estradiol (at menopause) in atrial substrate remodeling, atrial arrhythmogenesis and stroke risk in aged females.

Follicle-Stimulating Hormone Does Not Impact RANKL-Induced Osteoclastogenesis

Postmenopausal osteoporosis has been attributed to decreased estradiol levels. In the hypothalamic-pituitary-gonadal axis, estradiol synthesis is stimulated by follicle-stimulating hormone (FSH). FSH is secreted from the anterior pituitary gland and estradiol feeds back to the hypothalamus and pituitary to suppress FSH production. In postmenopausal women, the loss of estradiol (and inhibin) negative feedback leads to elevated serum FSH levels. It was recently proposed that this increase in FSH also contributes to postmenopausal osteoporosis by stimulating differentiation and activation of bone-resorbing osteoclast cells. Our objectives were to determine whether FSH has direct actions on osteoclast differentiation in vitro and, if so, its mechanism(s) of action. First, a murine leukemic monocyte/macrophage cell line, RAW264.7, was differentiated into osteoclasts by treatment with receptor activator of nuclear factor kappa-B ligand (RANKL, 50 ng/mL) for seven days. As expected, we observed the appearance of osteoclasts, characterized as tartrate-resistant acid phosphatase (TRAP)-positive multinucleated cells. RANKL also induced expression of established osteoclast differentiation markers, including Trap, cathepsin K (Ctsk), and matrix metalloproteinase-9 (Mmp9). The mRNA expression of FSH receptor (Fshr), however, was low to undetectable both before and after osteoclast differentiation. Co-treatment of RAW264.7 cells with FSH (35, 70 and 140 IU/L) and RANKL did not further impact the expression of Rank, Trap, Ctsk, Mmp-9, or Fshr. Second, primary murine monocytes were differentiated into osteoclasts by treatment with RANKL (50 ng/mL) and macrophage colony-stimulating factor (M-CSF, 25 ng/mL) for five days. FSH co-treatment (70 and 140 IU/L) had no impact on the expression of osteoclast markers, and Fshr expression was low to undetectable both before and after osteoclast differentiation, consistent with the results from RAW264.7 cells. In conclusion, in our hands, FSH does not impact RANKL-induced osteoclast differentiation in immortalized or primary murine monocytes.

Changes in nucleus accumbens gene expression accompany sex-specific suppression of spontaneous physical activity in aromatase knockout mice

Aromatase catalyzes conversion of testosterone to estradiol and is expressed in a variety of tissues, including the brain. Suppression of aromatase adversely affects metabolism and physical activity behavior, but mechanisms remain uncertain. The hypothesis tested herein was that whole body aromatase deletion would cause gene expression changes in the nucleus accumbens (NAc), a brain regulating motivated behaviors such as physical activity, which is suppressed with loss of estradiol. Metabolic and behavioral assessments were performed in male and female wild-type (WT) and aromatase knockout (ArKO) mice. NAc-specific differentially expressed genes (DEGs) were identified with RNAseq, and associations between the measured phenotypic traits were determined. Female ArKO mice had greater percent body fat, reduced spontaneous physical activity (SPA), consumed less energy, and had lower relative resting energy expenditure (REE) than WT females. Such differences were not observed in ArKO males. However, in both sexes, a top DEG was Pts, a gene encoding an enzyme necessary for catecholamine (e.g., dopamine) biosynthesis. In comparing male and female WT mice, top DEGs were related to sexual development/fertility, immune regulation, obesity, dopamine signaling, and circadian regulation. SPA correlated strongly with Per3, a gene regulating circadian function, thermoregulation, and metabolism (r = −0.64, P = .002), which also correlated with adiposity (r = 0.54, P = .01). In conclusion, aromatase ablation leads to gene expression changes in NAc, which may in turn result in reduced SPA and related metabolic abnormalities. These findings may have significance to post-menopausal women and those treated with an aromatase inhibitor.

Abstract 046: Chronic Estrogen Replacement Prevents the Increase in Blood Pressure in Female IUGR Offspring at 12 Months of Age

Low birth weight (LBW ) is associated with an earlier age at menopause and a greater prevalence of hypertension in women in later life. Using a rodent model of LBW induced by placental insufficiency, previous studies from our lab indicate that intrauterine growth restriction ( IUGR ) programs a significant increase in blood pressure ( BP ) by 12 months of age in female IUGR offspring. Female IUGR are also acyclic by 12 months of age, or 6 months prior to control indicative of early reproductive senescence. The mechanisms involved in menopause related cardiovascular risk are not clear. Furthermore, the link between birth weight and the greater prevalence for hypertension in LBW women in later life is not known. Female IUGR exhibit a shift in the testosterone to estradiol ratio at 12 months of age. Thus, this study tested the hypothesis that a loss of estradiol ( E2 ) contributes to the increase in BP in female IUGR offspring that develops by 12 months of age. Female rats received vehicle or 17β-Estradiol valerate minipellets (1.5mg for 60-day release) for 6 weeks starting at 12 months of age with BP measured in conscious, chronically catheterized rats following treatment (2way ANOVA; Tukey’s multiple comparison). BP was significantly increased in vehicle-treated IUGR relative to vehicle-treated Control (*, p&lt;0.05); an increase that was abolished by chronic E2 in IUGR (**, p&lt;0.05). Uterine weight, a crude marker of E2, was significantly increased by chronic E2 in both Control and IUGR E2-treated offspring (**, p&lt;0.05). Therefore, this study indicates that E2 withdrawal after early reproductive senescence contributes to the increase in BP that develops in later life in female IUGR offspring.

Altered Brain Connectivity in Early Postmenopausal Women with Subjective Cognitive Impairment.

Cognitive changes after menopause are a common complaint, especially as the loss of estradiol at menopause has been hypothesized to contribute to the higher rates of dementia in women. To explore the neural processes related to subjective cognitive complaints, this study examined resting state functional connectivity in 31 postmenopausal women (aged 50–60) in relationship to cognitive complaints following menopause. A cognitive complaint index was calculated using responses to a 120-item questionnaire. Seed regions were identified for resting state brain networks important for higher-order cognitive processes and for areas that have shown differences in volume and functional activity associated with cognitive complaints in prior studies. Results indicated a positive correlation between the executive control network and cognitive complaint score, weaker negative functional connectivity within the frontal cortex, and stronger positive connectivity within the right middle temporal gyrus in postmenopausal women who report more cognitive complaints. While longitudinal studies are needed to confirm this hypothesis, these data are consistent with previous findings suggesting that high levels of cognitive complaints may reflect changes in brain connectivity and may be a potential marker for the risk of late-life cognitive dysfunction in postmenopausal women with otherwise normal cognitive performance.

Prognostic factors in paediatric anaplastic large cell lymphoma role of ALK

A promising strategy to delay and perhaps prevent Alzheimer's disease (AD) is to identify the age-related changes that put the brain at risk for the disease. A significant normal age change known to result in tissue-specific dysfunction is the depletion of sex hormones. In women, menopause results in a relatively rapid loss of estradiol and progesterone. In men, aging is associated with a comparatively gradual yet significant decrease in testosterone. We review a broad literature that indicates age-related losses of estrogens in women and testosterone in men are risk factors for AD. Both estrogens and androgens exert a wide range of protective actions that improve multiple aspects of neural health, suggesting that hormone therapies have the potential to combat AD pathogenesis. However, translation of experimental findings into effective therapies has proven challenging. One emerging treatment option is the development of novel hormone mimetics termed selective estrogen and androgen receptor modulators. Continued research of sex hormones and their roles in the aging brain is expected to yield valuable approaches to reducing the risk of AD.

Endometriosis-induced vaginal hyperalgesia in the rat: Effect of estropause, ovariectomy, and estradiol replacement

Endometriosis (ENDO) is a painful disorder defined by extrauteral endometrial growths. It is created in rats by autotransplanting pieces of uterus (which form cysts), or, for shamENDO, fat (no cysts). ENDO induces vaginal hyperalgesia, likely via central sensitization. The severity of this hyperalgesia correlates with estradiol levels during the estrous cycle, suggesting the hyperalgesia is estradiol-modulated. If so, then hyperalgesic severity should track estradiol changes during reproductive senescence (estropause) when estradiol levels initially decrease, then increase. Using psychophysical methods to assess vaginal nociception, we found that the severity of ENDO-induced hyperalgesia paralleled estradiol changes during estropause: hyperalgesia first decreased, then returned. Furthermore, the return occurred regardless of the presence of the cysts (excised in some rats). This finding provides further support for ENDO’s likely centrally-mediated effects. Additionally, the results suggest that elimination of estradiol via ovariectomy (OVX) should alleviate ENDO-induced hyperalgesia and estradiol replacement should restore it. However, in healthy and shamENDO rats, OVX produces a vaginal hyperalgesia that is alleviated by estradiol, likely via estradiol’s peripheral influences on the vagina. Hence, we tested the hypothesis that OVX in ENDO rats would trigger a different type of vaginal hyperalgesia dependent on the loss of estradiol. We predicted that the opposing influences of estradiol on ENDO- and OVX-induced hyperalgesia would cancel each other. As predicted, OVX had no effect on ENDO-induced hyperalgesia and estradiol replacement alleviated it. These results suggest that, in intact rats, ENDO-induced vaginal hyperalgesia is exacerbated by estradiol, and that different mechanisms underlie ENDO-induced versus OVX-induced vaginal hyperalgesia.

Estradiol augments peri-infarct cerebral vascular density in experimental stroke

Peri-infarct increase of vascular density has been observed in animals and in humans with ischemic stroke. Increased peri-infarct vascular density correlates with improved functional outcome after stroke. We hypothesized that pre-treatment with estradiol will increase post-ischemic peri-infarct capillary density in a rat model of transient ischemic stroke. Estradiol, compared to placebo, augmented post-ischemic peri-infarct vascular density by 22% 10 days after stroke. Recovery of forelimb function was not improved with estradiol treatment on day three and nine post-stroke. Loss of estradiol may limit repair in the peri-infarct region by limiting angiogenesis, but functional significance in stroke recovery requires further investigation.

The role of intracellular equilibria and the effect of antiestrogens on estrogen-receptor dissociation kinetics from perfused cultures of human breast cancer cells.

Dissociation of [3H]estradiol from perfused monolayer cultures of estrogen receptor-positive MCF-7 human breast cancer cells is described. A kinetic model is proposed in which loss of estradiol from the cells occurs from an intracellular compartment of free estradiol that is in dynamic equilibrium with estradiol bound to both specific (receptor) and nonspecific cellular binding sites. We found that the estrogen receptor in MCF-7 cells has little effect on the dissociation rate constant of estradiol from MCF-7 cells by comparing the dissociation of estradiol from MCF-7 cells with estrogen receptor-negative MDA-MB-231 cells. The major determinant of the rate constant of estradiol dissociation from both MCF-7 and MDA-MB-231 cells is the equilibrium between free intracellular estradiol and estradiol bound to slowly dissociating nonspecific binding sites. This result indicates that slow dissociation of estradiol from nonspecific cellular binding sites may prolong the occupancy of specific receptor si tes. Thus...

ADRENAL AND TESTICULAR DEFICIENCY: A COMPARISON BASED ON SIMILARITIES IN ANDROGEN DEFICIENCY, ANDROGEN AND 17-KETOSTEROID EXCRETION, AND ON DIFFERENCES IN THEIR EFFECTS UPON PITUITARY ACTIVITY

ACCORDING to the theory that there is a second testicular hormone (inhibin), deficiency of this factor, as in the human castrate or in severe testicular failure, is chiefly responsible for the ensuing pituitary hyperactivity. It is generally conceded that androgens arise in the cortex of the adrenal gland as well as in the Leydig cells of the testes. The androgens arising in the testes, together with the androgens and other related substances arising in the cortex of the adrenal, are largely represented in the urine as a group of substances known as 17-ketosteroids. Measurement of these is frequently used to estimate certain hormonal activities of the testes and the adrenal glands. Androgenic activity per se is measurable biologically. In women with ovarian deficiency the cause of pituitary hyperactivity apparently is the loss of estradiol. The high levels of urinary follicle-stimulating hormone (F.S.H.) occurring after castration or the menopause can be reduced by small amounts of estradiol or other estr...