The effects of transdermal estradiol on the response to mental stress in postmenopausal women: a randomized trial

Impacts of Psychological Stress on Osteoporosis: Clinical Implications and Treatment Interactions

The significant biochemical and physiological effects of psychological stress are beginning to be recognized as exacerbating common diseases, including osteoporosis. This review discusses the current evidence for psychological stress-associated mental health disorders as risk factors for osteoporosis, the mechanisms that may link these conditions, and potential implications for treatment. Traditional, alternative, and adjunctive therapies are discussed. This review is not intended to provide therapeutic recommendations, but, rather, the goal of this review is to delineate potential interactions of psychological stress and osteoporosis and to highlight potential multi-system implications of pharmacological interventions. Review of the current literature identifies several potentially overlapping mechanistic pathways that may be of interest (e.g., glucocorticoid signaling, insulin-like growth factor signaling, serotonin signaling) for further basic and clinical research. Current literature also supports the potential for cross-effects of therapeutics for osteoporosis and mental health disorders. While studies examining a direct link between osteoporosis and chronic psychological stress are limited, the studies reviewed herein suggest that a multi-factorial, personalized approach should be considered for improved patient outcomes in populations experiencing psychological stress, particularly those at high-risk for development of osteoporosis.

Estradiol Therapy After Menopause Mitigates Effects of Stress on Cortisol and Working Memory

Context

Postmenopausal estradiol therapy (ET) can reduce the stress response. However, it remains unclear whether such reductions can mitigate effects of stress on cognition.

Objective

Investigate effects of ET on cortisol response to a physical stressor, cold pressor test (CPT), and whether ET attenuates stress effects on working memory.

Design

Women completed the CPT or control condition across two sessions and subsequently completed a sentence span task.

Setting

General community: Participants were recruited from the Early vs Late Intervention Trial with Estradiol (ELITE).

Participants

ELITE participants (mean age = 66, standard deviation age = 6.8) in this study did not suffer from any major chronic illness or use medications known to affect the stress response or cognition.

Interventions

Participants had received a median of randomized 4.7 years of estradiol (n = 21) or placebo (n = 21) treatment at time of participation in this study.

Main Outcome Measures

Salivary cortisol and sentence span task performance.

Results

Women assigned to estradiol exhibited blunted cortisol responses to CPT compared with placebo (P = 0.017) and lesser negative effects of stress on working memory (P = 0.048).

Conclusions

We present evidence suggesting ET may protect certain types of cognition in the presence of stress. Such estrogenic protection against stress hormone exposure may prove beneficial to both cognition and the neural circuitry that maintains and propagates cognitive faculties.

Actions and interactions of estradiol and glucocorticoids in cognition and the brain: Implications for aging women

Menopause involves dramatic declines in estradiol production and levels. Importantly, estradiol and the class of stress hormones known as glucocorticoids exert countervailing effects throughout the body, with estradiol exerting positive effects on the brain and cognition, glucocorticoids exerting negative effects on the brain and cognition, and estradiol able to mitigate negative effects of glucocorticoids. Although the effects of these hormones in isolation have been extensively studied, the effects of estradiol on the stress response and the neuroprotection offered against glucocorticoid exposure in humans are less well known. Here we review evidence suggesting that estradiol-related protection against glucocorticoids mitigates stress-induced interference with cognitive processes. Animal and human research indicates that estradiol-related mitigation of glucocorticoid damage and interference is one benefit of estradiol supplementation during peri-menopause or soon after menopause. The evidence for estradiol-related protection against glucocorticoids suggests that maintaining estradiol levels in post-menopausal women could protect them from stress-induced declines in neural and cognitive integrity.

Lipopolysaccharide-binding protein and leptin are associated with stress-induced interleukin-6 cytokine expression ex vivo in obesity

Obesity is associated with enhanced inflammation and mental stress, but limited information has addressed the potential additive effect of psychological stress on obesity-associated inflammation. This study examined whether obese subjects would elicit a greater host immune response (IL-6 mRNA and cytokine) to lipopolysaccharide (LPS) in response to mental stress. Blood samples for LPS-stimulated IL-6 mRNA and cytokine were collected prior to and following mental stress. Results showed that obese subjects elicited a greater LPS-induced IL-6 along with its mRNA expression following mental stress compared to normal-weight subjects. Stress-induced IL-6 cytokine response to LPS was correlated with the baseline levels of plasma LPS binding protein (LBP) and leptin. These findings are consistent with the idea that endogenous inflammatory agents (e.g., LBP and leptin), often elevated with obesity, enhance inflammatory responses to psychological stress.

Cardiorespiratory fitness does not alter plasma pentraxin 3 and cortisol reactivity to acute psychological stress and exercise

Pentraxin 3 (PTX3) has been recently identified as a biomarker of vascular inflammation in predicting cardiovascular events. The purpose of this study was to examine the effect of cardiorespiratory fitness on plasma PTX3 and cortisol responses to stress, utilizing a dual-stress model. Fourteen male subjects were classified into high-fit (HF) and low-fit (LF) groups and completed 2 counterbalanced experimental conditions. The exercise-alone condition (EAC) consisted of cycling at 60% maximal oxygen uptake for 37 min, while the dual-stress condition (DSC) included 20 min of a mental stress while cycling for 37 min. Plasma PTX3 revealed significant increases over time with a significant elevation at 37 min in both HF and LF groups in response to EAC and DSC. No difference in plasma PTX3 levels was observed between EAC and DSC. In addition, plasma cortisol revealed a significant condition by time interaction with greater levels during DSC at 37 min, whereas cardiorespiratory fitness level did not reveal different plasma cortisol responses in either the EAC or DSC. Aerobic exercise induces plasma PTX3 release, while additional acute mental stress, in a dual-stress condition, does not exacerbate or further modulate the PTX3 response. Furthermore, cardiorespiratory fitness may not affect the stress reactivity of plasma PTX3 to physical and combined physical and psychological stressors. Finally, the exacerbated cortisol responses to combined stress may provide the potential link to biological pathways that explain changes in physiological homeostasis that may be associated with an increase in the risk of cardiovascular disease.

Stress-induced microvascular reactivity in normal-weight and obese individuals

Obesity has been shown to have profound effects on hemodynamics and neurological states in humans. Previous studies have demonstrated that obese individuals are highly susceptible to increases in tension, anxiety, and depression. However, the relationship between mental stressors and vascular fluidity in obese humans is not well understood. Thus, the purpose of this study was to investigate mental-stress-induced microvascular reactivity (excess blood flow (EBF)) in normal-weight and obese individuals. In addition, the relationships between potential vascular response modulators (heart rate (HR) and norepinephrine (NE)) and EBF were examined. Twenty-two male subjects were classified as obese (n = 12) or normal-weight (n = 10), and each subject completed a 20 min bout of acute mental stress. Our analyses demonstrate significant elevations in forearm blood flow (FBF) and EBF immediately after mental stress in both normal-weight and obese groups. HR was only correlated with EBF immediately poststress in the normal-weight group. Furthermore, stress-induced plasma NE was not associated with FBF or EBF in either group, although in the obese group, stress-induced plasma NE was associated with body mass index and percent body fat. These results suggest that microvascular reactivity after mental stress is not directly related to plasma NE in normal-weight or obese individuals. The novel results presented in this study provide a foundation for additional examination of the mechanisms involved in the effects of mental stress on microvascular reactivity.

Estrogen mediation of hormone responses to exercise

The roles of estrogens extend from the regulation of reproduction to other functions involved in control of metabolism, fluid balance, as well as gastrointestinal, lung, and brain function, with a strong effect on other hormones that subsequently alter the physiology of multiple tissues. As such, alteration of endogenous estrogens across the menstrual cycle, or from oral contraception and estrogen replacement therapy, can affect these tissues. Due to the important effects that estrogens have on different tissues, there are many investigations concerning the effects of a human estrogenic environment on endocrine responses to exercise. The following review will describe the consequences of varying estrogen levels on pituitary, adrenal, gonadal, and endocrine function, followed by discussion of the outcomes of different estrogen levels on endocrine tissues in response to exercise, problems encountered for interpretation of findings, and recommended direction for future research.

The effects of age and estrogen on stress responsivity in older women

OBJECTIVE

The current study examined whether age after menopause impacted the effect of estradiol (E2) on mood after a psychosocial stress manipulation.

BACKGROUND

Previous studies have shown that E2 improves mood in women around the menopause transition but does not improve mood for older postmenopausal women. We have previously shown that E2 treatment in nondepressed women resulted in increased negative mood after psychosocial stress.

DESIGN

Participants were 22 postmenopausal women placed on either oral placebo or 17β-estradiol (1 mg/day for 1 month, then 2 mg/day for 2 months).

METHOD

At the end of the 3-month treatment phase, the participants performed the Trier Social Stress Test followed by mood ratings. To examine the effects of age on the estrogen-stress interaction, we performed a median split on age and created four groups of participants: younger-placebo (mean age: 55.5 years), younger-E2 (mean age: 55.5 years), older-placebo (mean age: 73.0 years), and older-E2 (mean age: 76.8 years).

RESULTS

: The results showed that both older and younger E2-treated participants exhibited a significant and similar increase in negative mood after psychosocial stress compared with placebo-treated women.

CONCLUSIONS

These results suggest that E2 may play a significant role in modulating emotional reactivity to stressful events and that this effect persists in older women. Furthermore, responsivity to E2 effects on emotional processing appears to be intact even years after menopause in contrast with other cognitive and behavioral effects of E2, which may be limited to the early postmenopausal years.

Stress, inflammation, and aging

This editorial provides a summary of the state of research on stress-related changes associated with aging and discuss how factors such as inflammation and sex steroid alterations may interact with psychosocial stress to affect the risk for mood and cognitive disturbance in older individuals. The authors provide an integrated summary of four studies reported in this issue of the journal and views on future direction in stress and aging research and interventions targeting resilience to stress.

LPS-stimulated tumor necrosis factor-alpha and interleukin-6 mRNA and cytokine responses following acute psychological stress

The purpose of this study was to examine the effect of acute psychological stress on LPS-stimulated TNF-α and IL-6 mRNA expression. Twenty-one healthy male subjects participated in 20 min of acute stress. Blood samples for norepinephrine and LPS-stimulated TNF-α and IL-6 cytokines and mRNA were drawn prior to, immediately after and 1-h after stress. Stress-induced increases in anxiety scores, cortisol, plasma norepinephrine, and heart rate demonstrated that the experimental protocol elicited an acute stress response. LPS-stimulated TNF-α mRNA decreased significantly immediately post-stress and partially recovered at 1h post-stress, whereas LPS-stimulated IL-6 mRNA exhibited a significant change across time, with an increase immediately after stress and a decrease 1h after stress. Trends in LPS-stimulated TNF-α and IL-6 cytokine concentrations followed the patterns of mRNA expression. A negative correlation of body mass index (BMI) and percent change of LPS-stimulated TNF-α mRNA was observed immediately post-stress, and BMI positively correlated with percent change of LPS-stimulated IL-6 cytokine levels immediately following stress. These findings demonstrated that acute psychological stress affects LPS-stimulated IL-6 and TNF-α gene expression. These results also indicate that BMI may impact the effects of psychological stress on cytokine responses to immune challenge. Further examination of the effects of stress on synthesis of other cellular cytokines and investigation of the association of BMI and stress responses will provide a more clear representation of the cytokine responses to acute psychological stress. In addition, studies examining the influence of gender on the response of immune cell subsets to acute stress and the possible mediating effect of BMI are warranted.

Cognitive response to estradiol in postmenopausal women is modified by high cortisol

Estradiol has potent favorable effects on brain function and behavior in animals while in human trials, the results are inconsistent. A number of potential mediating variables influencing response to estradiol have been proposed to account for this variability, 1 of which includes stress. We conducted a placebo-controlled study to examine joint and independent effects of estradiol and elevated levels of the stress hormone cortisol on cognition and biomarkers of aging and neurodegenerative disease. Thirty-nine healthy postmenopausal women (56-84 years) received 0.10 mg/dL of transdermal 17β-estradiol (E2) or placebo for 8 weeks. During the last 4 days of the trial, subjects also received 90 mg/day (30 mg 3×/day) of oral hydrocortisone (CORT) to induce stress-level elevations in cortisol, or a matched placebo. The 4 groups thus included placebo (placebo patch/placebo pill), CORT-alone (placebo patch/hydrocortisone), E2-alone (estradiol patch/placebo pill), and E2+CORT (estradiol patch/hydrocortisone). Eight weeks of E2 increased plasma estradiol by 167%, and 4 days of CORT increased plasma cortisol by 119%. Overall, E2 had favorable effects on verbal memory (p = 0.03), working memory (p = 0.02), and selective attention (p = 0.04), and the magnitude of these effects was attenuated for E2+CORT. E2-alone and E2+CORT had opposing effects on plasma levels of the amyloid-β (Aβ) biomarker (Aβ40/42 ratio, p < 0.05), with the more favorable response observed for E2-alone. CORT-induced increases in insulin-like growth factor-1 were blunted by E2 coadministration. Our findings indicate that cognitive and physiological responses to estradiol are adversely affected by elevated stress hormone levels of cortisol in healthy postmenopausal women.

Psychological stress during exercise: immunoendocrine and oxidative responses

The purpose of this study was to examine the changes in catecholamines (epinephrine [EPI] and norepinephrine [NE]), interleukin-2 (IL-2) and a biomarker of oxidative stress (8-isoprostane) in healthy individuals who were exposed to a dual challenge (physical and psychological stress). Furthermore, this study also examined the possible relationships between catecholamines (NE and EPI) and 8-isoprostane and between IL-2 and 8-isoprostane following a combined physical and psychological challenge. Seven healthy male subjects completed two experimental conditions. The exercise-alone condition (EAC) consisted of cycling at 60% VO(2max) for 37 min, while the dual-stress condition (DSC) included 20 min of a mental challenge while cycling. DSC showed greater EPI and 8-isoprostane levels (significant condition by time interaction). NE and IL-2 revealed significant change across time in both conditions. In addition, following dual stress, EPI area-under-the-curve (AUC) demonstrated a positive correlation with NE AUC and IL-2 AUC. NE AUC was positively correlated with IL-2 AUC and peak 8-isoprostane, and peak IL-2 was positively correlated with peak 8-isoprostane in response to a dual stress. The potential explanation for elevated oxidative stress during dual stress may be through the effects of the release of catecholamines and IL-2. These findings may further provide the potential explanation that dual stress alters physiological homeostasis in many occupations including firefighting, military operations and law enforcement. A greater understanding of these responses to stress can assist in finding strategies (e.g. exercise training) to overcome the inherent psychobiological challenges associated with physically and mentally demanding professions.

Estrogen treatment impairs cognitive performance after psychosocial stress and monoamine depletion in postmenopausal women

OBJECTIVE

Recent studies have shown that women experience an acceleration of cognitive problems after menopause and that estrogen treatment can improve or at least maintain current levels of cognitive functioning in postmenopausal women. However, we have previously shown that the negative emotional effects of psychosocial stress are magnified in normal postmenopausal women after estrogen treatment. This study examined whether estradiol (E2) administration can modify cognitive performance after exposure to psychological stress and monoamine depletion.

METHODS

Participants consisted of 22 postmenopausal women placed on either oral placebo or 17beta-E2 (1 mg/d for 1 mo, then 2 mg/d for 2 mo). At the end of the 3-month treatment phase, participants underwent three depletion challenges in which they ingested one of three amino acid mixtures: deficient in tryptophan, deficient in phenylalanine/tyrosine, or balanced. Five hours later, participants performed the Trier Social Stress Test (TSST), followed by mood and anxiety ratings and cognitive testing. Cognitive measures included tests of attention, psychomotor function, and verbal episodic memory.

RESULTS

E2-treated compared with placebo-treated participants exhibited significant worsening of cognitive performance on tasks measuring attentional performance and psychomotor speed. Similar trends for impairment were seen in measures of long-term episodic memory compared with placebo-treated postmenopausal women. E2-treated participants also showed a significant increase in negative mood and anxiety compared with placebo-treated women after, but not before, the TSST, although the worsening of both cognitive and behavioral functioning was not correlated. These effects were independent of tryptophan or tyrosine/phenylalanine depletion and were not manifested before the TSST or at baseline.

CONCLUSIONS

These data suggest that the relationship between estrogen administration and cognitive/behavioral performance in postmenopausal women may be more complex than initially appreciated and that the effects of psychosocial stress may influence whether hormone effects are beneficial.

Estrogen administration negatively alters mood following monoaminergic depletion and psychosocial stress in postmenopausal women

Differences in the rates of affective disorders between women and men may relate to gender differences in gonadal steroid levels such as estrogen that have effects on brain monoamines important to mood regulation. Changes in estrogen secretion patterns during the perimenopause and menopause may be relevant to the increased risk for affective symptoms at that time. This study examined whether 17beta-estradiol (E2) administration can modify the mood effects of experimental psychosocial stress following acute monoamine depletion in postmenopausal women. Subjects consisted of 15 normal postmenopausal women (PMW) (ages 67.1+/-11.2 years) blindly placed on either oral placebo or E2 (1 mg/day for 1 month, then 2 mg/day for 2 months). At the end of the 3-month treatment phase, subjects participated in three blinded depletion challenges in which they ingested each of three amino-acid mixtures: deficient in tryptophan, deficient in phenylalanine/tyrosine, or nutritionally balanced. After 5 h, subjects performed the Trier Social Stress Test (TSST), followed by mood and anxiety ratings. E2-treated subjects exhibited a significant increase in negative mood and anxiety after the TSST compared to placebo-treated women. These effects were independent of monoamine depletion and were not manifest before the TSST or at baseline. Exogenous estrogen administration in PMW may alter or modulate emotional reactivity to stressful events and may alter the sensitivity of emotional regulation. This modulation appears to be independent of alterations in monoaminergic neurotransmission. The dose of estrogen used after menopause may be important in determining the effects of gonadal steroids on emotional regulation.

Mental stress induces sustained elevation of blood pressure and lipid peroxidation in postmenopausal women

Mental stress is thought to underlie cardiovascular events, but there is information on oxidative stress induced by mental stress in association with cardiovascular responses in women. Using a sensitive assay for plasma 4-hydroxy-2-nonenal (HNE), as a marker for oxidative stress, we addressed the relation between pressor responses and oxidative stress induced by mental or physical stress in premenopausal and postmenopausal women. Healthy subjects (7 postmenopausal and 8 premenopausal women, in early and late follicular phases) were subjected to mental and physical stress evoked by a Color Word Test (CWT) and isometric handgrip, respectively. The CWT induced a rapid elevation of diastolic blood pressure (DBP), at a higher level in the postmenopausal than in the premenopausal women (p<0.01), and this higher DBP was sustained during the CWT and recovery (p<0.01). The CWT induced a significant elevation in plasma noradrenaline in premenopausal women in the early follicular phase and in postmenopausal women (p<0.05). Plasma nitric oxide metabolites were higher in postmenopausal than in the premenopausal women in the late follicular phase (p<0.05), but did not change during exposure to the two types of stress in either group. Plasma HNE was increased during recovery from the CWT, but not the handgrip, in postmenopausal women (2.4 times, p<0.05). There was a significant difference in the time course of the CWT-induced HNE response between the postmenopausal and premenopausal women (p<0.05). These findings suggest that mental, but not physical, stress causes sustained diastolic blood pressure elevation in postmenopausal women, accompanied by heightened oxidative stress.

Tumor Necrosis Factor-α and Vascular Angiotensin II in Estrogen-Deficient Rats

Alterations in the vascular angiotensin II system may play a role in the pathophysiology of vascular disease after menopause. In previous studies we have shown that an increase in tumor necrosis factor (TNF)-α levels in aging rats because of estrogen deficiency may result in vascular dysfunction. In this study we investigated the effect of TNF-α inhibition in angiotensin II modulation of vascular function in aging female animals. Female rats approaching reproductive senescence (12 to 15 months old) were ovariectomized and treated with placebo, estrogen, or a selective TNF-α inhibitor (etanercept) for 4 weeks. Expression of angiotensin II in mesenteric arteries was evaluated by immunofluorescence, and the expression of angiotensin-converting enzyme and angiotensin type I receptor (AT 1 R) was investigated by Western immunoblot. Vascular function was assessed in mesenteric arteries using the myograph system, and the role of endogenous angiotensin II on adrenergic vasoconstriction was evaluated in vitro by selective AT 1 R blockade (Candesartan; 10 μmol/L). Our data demonstrate that estrogen-depleted rats have higher serum levels of TNF-α and greater sensitivity to phenylephrine vasoconstriction compared with estrogen-replaced animals, which was attenuated by AT 1 R blockade. In vivo TNF-α inhibition or estrogen replacement reduced phenylephrine constriction of mesenteric arteries and decreased the modulation of this vasoconstriction by candesartan. These functional changes were accompanied by a reduction in the vascular expression of angiotensin II, angiotensin-converting enzyme, and AT 1 R. These observations indicate that upregulation of TNF-α during estrogen deficiency may contribute to enhance vascular constriction by altering the vascular angiotensin II system.

Modulation of hypoglycemia-induced increases in plasma epinephrine by estrogen in the female rat

Clinical studies have demonstrated that estrogen replacement therapy suppresses stress-induced increases in plasma catecholamines. The present study determined whether normal circulating levels of estrogen can modulate hypoglycemia-induced increases in plasma epinephrine (EPI). In anesthetized female rats, insulin-induced hypoglycemia (0.25 U/kg) increased plasma EPI concentration to a significantly greater extent in 14-day ovariectomized (OVEX) rats compared to that in sham-operated controls. In 17beta-estradiol (E2)-replaced OVEX rats, the hypoglycemia-induced rise in plasma EPI was reduced significantly when compared to that in vehicle-replaced OVEX rats. OVEX and E2 replacement had no effect on tyrosine hydroxylase or phenylethanolamine N-methyltransferase mRNA levels in the adrenal medulla. In isolated adrenal medullary chromaffin cells, agonist-induced increases in intracellular Ca2+ were unaffected by 48-hr exposure to 10 nM E2. In contrast, acute (3-min) exposure to micromolar concentrations of E2 dose-dependently and reversibly inhibited agonist-induced Ca2+ transients. In addition, in OVEX rats, a constant infusion of E2 significantly reduced the insulin-induced increase in plasma EPI concentration compared to that in vehicle-infused controls. These data demonstrate that physiologic levels of circulating E2 can modulate hypoglycemia-induced increases in plasma EPI. This effect seems independent of steroid influence on adrenal medullary secretion or biosynthesis. In contrast, acute exposure to high levels of E2 can also suppress hypoglycemia-induced increases in plasma epinephrine, due at least in part to inhibition of stimulus-secretion coupling.

Efficiency of the cross-over design: an empirical estimation

The aim of the present study is to estimate the relative efficiency of cross-over clinical trials as compared to the corresponding parallel designs. A MEDLINE 'full text' search covering years 2000-2003 over the word 'cross-over' identified 40 true cross-over studies with the parametric approach published in leading medical journals. A parallel design is expected to need, in order to achieve the same power, between 4 and 10 times more subjects than the corresponding cross-over design, meaning that cost of a parallel design can be between 2 and 5 times higher. There is a high proportion (18/40 = 45.0 per cent) of cross-over studies recently published in leading medical journals that, disregarding the CONSORT recommendations, does not provide estimates for the effect size and its standard error, hence, not allowing for the posterior use of the data in a meta-analysis.

Influence of hormone therapy on the cardiovascular responses to stress of postmenopausal women

Epidemiological and psychophysiological data suggest that groups that differ in reproductive hormones and stress responses also differ in risk for cardiovascular disease. To evaluate the effects of hormone therapy on women's cardiovascular responses to laboratory stressors, 89 healthy postmenopausal women were tested twice, before and after exposure for about 8 weeks to one of the five conditions: placebo, Estratab (primarily estrone), Estratab plus Prometrium (micronized progesterone), Estratab plus Provera (synthetic progestin), and Estratest (same estrogen as in Estratab plus methyltestosterone). Results showed that women assigned to Estratab plus Prometrium and Estratest had diminished systolic blood pressure responses to stress upon retesting, whereas the other groups did not change in the level of their responses. Women assigned to Estratab plus Prometrium had diminished diastolic blood pressure responses during a speech stressor upon retesting, whereas women assigned to Estratab plus Provera increased. Our findings show that hormone therapy does affect women's stress responses, but they do not provide a simple explanation as to why groups at high and low risk for cardiovascular disease differ in reproductive hormones and stress responses.

Estrogen replacement suppresses stress-induced cardiovascular responses in ovariectomized rats

We assessed the hypothesis that chronic estrogen replacement in ovariectomized rats has the beneficial effect of suppressing stress-induced cardiovascular responses through endothelial nitric oxide synthase (eNOS). We employed a radiotelemetry system to measure blood pressure and heart rate (HR). Female Wistar rats aged 11 wk were ovariectomized and implanted with radiotelemetry devices. After 4 wk, the rats were assigned either to a placebo-treated group (Placebo; n = 6) or a group treated with 17β-estradiol (Estrogen; n = 8) subcutaneously implanted with either placebo- or 17β-estradiol (1.5 mg/60-day release) pellets under anesthesia. These rats underwent either of the two types of stress after 4 wk of estrogen or placebo treatment. Cage-switch stress and restraint stress rapidly and continuously elevated the mean arterial pressure (MAP) and HR both in the Placebo and Estrogen groups. However, the MAP and HR responses to cage-switch stress and the MAP but not HR response to restraint stress were attenuated significantly in the Estrogen group compared with the Placebo group. A NOS inhibitor, NG-nitro-l-arginine methyl ester, given in drinking water, reduced the difference in the pressor response to cage-switch between the Estrogen and Placebo groups. In addition, Western blot analysis showed that eNOS expression in the mesentery was increased in the Estrogen group compared with the Placebo group. Thus for the first time we showed that mesenteric eNOS overexpression could explain at least partly why chronic estrogen treatment suppressed the enhanced cardiovascular responses to psychological stress in the ovariectomized rat.

Catecholamines block the antimitogenic effect of estradiol on human coronary artery smooth muscle cells

Sequential conversion of estradiol to catecholestradiols and methoxyestradiols by cytochrome-P(450) (CYP450) and catechol-O-methyltransferase (COMT), respectively, contributes to the antimitogenic effects of estradiol on vascular smooth muscle cell (SMC) growth via estrogen receptor-independent mechanisms. Because catecholamines are also substrates for COMT, we hypothesize that catecholamines may abrogate the vasoprotective effects of estradiol by competing for COMT and inhibiting methoxyestradiol formation. To test this hypothesis, we investigated the antimitogenic/inhibitory effects of estradiol on human coronary artery SMC growth (cell number, DNA synthesis, collagen synthesis, and SMC migration) and ERK1/2 phosphorylation in the presence and absence of catecholamines. Norepinephrine, epinephrine, isoproterenol, and OR486 (COMT inhibitor) abrogated the inhibitory effects of estradiol on SMC growth and ERK1/2 phosphorylation. The interaction of catecholamines with estradiol was not affected by phentolamine or propanolol, alpha- and beta-adrenoceptor antagonists, respectively. The antimitogenic effects of 2-hydroxy-estradiol, but not 2-methoxyestradiol, were abrogated by epinephrine, isoproterenol, and OR486. Catecholamines inhibited the conversion of both estradiol and 2-hydroxy-estradiol to 2-methoxyestradiol, and SMCs expressed CYP1A1 and CYP1B1. Our findings suggest that catecholamines within the coronary arteries may abrogate the antivasoocclusive effects of estradiol by blocking the conversion of catecholestradiols to methoxyestradiols. The interaction between catecholamines and estradiol metabolism may importantly define the cardiovascular effects of estradiol therapy in postmenopausal women.

Pubertal and gender-related changes in the sympathoadrenal system in healthy children

A critical amount of body fat is necessary for the initiation of puberty, and leptin, an adipocyte-derived hormone, is necessary for pubertal development. The sympathoadrenal system modulates body fat stores and leptin secretion and interacts with adrenocortical androgen production, suggesting a possible role in sexual maturation. We studied sympathetic nerve and adrenomedullary activity at rest in 80 healthy children (ages, 5-17 yr; 37 boys and 43 girls) in relation to age, pubertal stage, gender, physical activity, body mass index, and serum levels of sex steroids, dehydroepiandrosterone sulfate, cortisol, leptin, and insulin. Plasma concentrations of the adrenomedullary hormone, epinephrine (E), and its metabolite metanephrine (MN), decreased significantly with advancing puberty and were higher in boys than in girls. E and MN correlated significantly and inversely with dehydroepiandrosterone sulfate, estradiol, testosterone, leptin, and insulin. Plasma norepinephrine, which is primarily derived from sympathetic nerve endings, increased significantly with advancing puberty and increasing testosterone levels in boys. Stepwise multiple regression analysis revealed that E was best predicted by pubertal stage and leptin, and MN by estradiol and leptin. Our data suggest that sympathoadrenal hormones may play a role in the complex process of sexual maturation. Further studies are needed to investigate a possible modulatory role of the adrenal medulla in the body weight-related timing of adrenarche and/or gonadarche.