Effect of estradiol on the sympathoadrenal response to mental stress in normal men

Gender Differences in Patients with Takotsubo Cardiomyopathy: Multi-Center Registry from Tokyo CCU Network

Background

The clinical features of gender differences in takotsubo cardiomyopathy (TC) remain to be determined. The aim of this study was to evaluate the differences in clinical characteristics of male and female patients with TC.

Methods

We obtained the clinical information of 368 patients diagnosed with TC (84 male, 284 female) from the Tokyo CCU Network database collected from 1 January 2010 to 31 December 2012; the Network is comprised of 71 cardiovascular centers in the Tokyo (Japan) metropolitan area. We attempted to characterize clinical differences during hospitalization, comparing male and female patients with TC.

Results

There were no significant differences in apical ballooning type, median echocardiography ejection fraction, serious ventricular arrhythmias (such as ventricular tachycardia or fibrillation), or cardiovascular death between male and female patients. Male patients were younger than female patients (median age at hospitalization for male patients was 72 years vs. 76 years for female patients; p = 0.040). Prior physical stress was more common in male than female patients (50.0% vs.31.3%; p = 0.002), while emotional stress was more common in female patients (19.0% vs. 31.0%; p = 0.039). Severe pump failure (defined as Killip Class > III) (20.2% vs. 10.6%; p = 0.020) and cardiopulmonary supportive therapies (28.6% vs. 12.7%, p < 0.001) were more common in male than female patients. Multivariate analysis revealed that male gender (odds ratio = 4.32, 95% CI = 1.41–13.6, p = 0.011) was an independent predictor of adverse composite cardiac events, including cardiovascular death, severe pump failure, and serious ventricular arrhythmia.

Conclusions

Cardiac complications in our dataset appeared to be more common in male than female patients with TC during their hospitalization. Further investigation is required to clarify the underlying mechanisms responsible for the observed gender differences.

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.

Mechanisms underlying hemodynamic and neuroendocrine stress reactivity at different phases of the menstrual cycle

This study examined the association of menstrual cycle phase with stress reactivity as well as the hormonal and neuroendocrine mechanisms contributing to cycle effects. Fifty-seven women underwent a modified Trier Social Stress Test during the early follicular, late follicular, and luteal phases of the menstrual cycle. Greater increases in cardiac index (CI) and greater decreases in vascular resistance index (VRI) during speech were observed in the luteal phase relative to other phases, while greater increases in epinephrine (EPI) was observed during the late follicular and luteal phases compared to the early follicular phase. Luteal phase estradiol predicted luteal EPI reactivity but not CI or VRI reactivity, while luteal phase EPI reactivity predicted luteal phase CI and VRI reactivity. Thus, cycle-related changes in EPI reactivity may be a stronger determinant of cycle effects on hemodynamic reactivity than sex hormones per se.

Sex differences in forebrain and cardiovagal responses at the onset of isometric handgrip exercise: a retrospective fMRI study

In general, cardiac regulation is dominated by the sympathetic and parasympathetic nervous systems in men and women, respectively. Our recent study had revealed sex differences in the forebrain network associated with sympathoexcitatory response to baroreceptor unloading. The present study further examined the sex differences in forebrain modulation of cardiovagal response at the onset of isometric exercise. Forebrain activity in healthy men (n = 8) and women (n = 9) was measured using functional magnetic resonance imaging during 5 and 35% maximal voluntary contraction handgrip exercise. Heart rate (HR), mean arterial pressure (MAP), and muscle sympathetic nerve activity (MSNA) were collected in a separate recording session. During the exercise, HR and MAP increased progressively, while MSNA was suppressed (P < 0.05). Relative to men, women demonstrated smaller HR (8 +/- 2 vs. 18 +/- 3 beats/min) and MAP (3 +/- 2 vs. 11 +/- 2 mmHg) responses to the 35% maximal voluntary contraction trials (P < 0.05). Although a similar forebrain network was activated in both groups, the smaller cardiovascular response in women was reflected in a weaker insular cortex activation. Nevertheless, men did not show a stronger deactivation at the ventral medial prefrontal cortex, which has been associated with modulating cardiovagal activity. In contrast, the smaller cardiovascular response in women related to their stronger suppression of the dorsal anterior cingulate cortex activity, which has been associated with sympathetic control of the heart. Our findings revealed sex differences in both the physiological and forebrain responses to isometric exercise.

Chronic estradiol and progesterone treatment in conscious dogs: effects on insulin sensitivity and response to hypoglycemia

We evaluated the effect of chronic (3 wk) subcutaneous treatment with progesterone and estradiol (PE; producing serum levels observed in the 3rd trimester of pregnancy) or placebo (C) on hepatic and whole body insulin sensitivity and response to hypoglycemia in conscious, overnight-fasted nonpregnant female dogs, using tracer and arteriovenous difference techniques. Insulin was infused peripherally for 3 h at 1.8 mU x kg(-1) x min(-1). Glucose was allowed to fall to 3 mM (Hypo) or maintained at 6 mM (Eugly) by peripheral glucose infusion. Insulin concentrations were significantly higher in Eugly-PE (n = 7) and Hypo-PE (n = 7) than in Eugly-C (n = 6) and Hypo-C groups (n = 7), but there were no significant differences in hepatic insulin extraction. Concentrations of glucagon, cortisol, epinephrine, and norepinephrine did not differ significantly between Eugly groups or between Hypo groups. Whole body glucose disposal, adjusted for the differences in insulin between groups, was 35% higher in Eugly-C vs. Eugly-PE groups (P < 0.05). Eugly-C and Eugly-PE groups exhibited similar rates of net hepatic glucose uptake, but the rate of glucose appearance was greater in Eugly-PE in the last hour (P < 0.05). Net hepatic glucose output was greater (P < 0.05) in Hypo-PE than in Hypo-C groups, and the glucose infusion rate required to maintain equivalent hypoglycemia was less (P < 0.05). The rate of gluconeogenic flux did not differ between Hypo groups. Chronic progesterone and estradiol exposure caused whole body (primarily skeletal muscle) insulin resistance and enhanced the liver's response to hypoglycemia without altering counterregulatory hormone concentrations.

Effect of testosterone replacement therapy on the somatotrope responsiveness to GHRH alone or combined with pyridostigmine and on sympathoadrenal activity in patients with hypogonadism

There is evidence suggesting that androgens influence GH secretion in man. Our aim was to verify whether the GH releasable pool is preserved and influenced by testosterone replacement in male hypogonadism. To this goal, in eight male hypogonadal patients (HP, age 32.2 +/- 5.0 yr; Body Mass Index 23.9 +/- 1.1 kg/m2) before and after 3 months testosterone therapy, we studied the GH response to GHRH (1 microgram/kg iv) alone and combined with pyridostigmine (PD, 120 mg po), a cholinesterase inhibitor which likely inhibits hypothalamic somatostatin release allowing exploration of the maximal somatotrope secretory pool. Sixteen normal subjects (NS, age 30.1 +/- 3.5 yr; Body Mass Index 22.5 +/- 1.8 kg/m2) were studied as controls. The GH response to GHRH in HP was similar to that in NS (AUC, mean +/- SE: 1238 +/- 362 vs 1018 +/- 182 micrograms/L/h). PD potentiated to the same extent the GH response to GHRH in both groups (2092 +/- 807 and 2840 +/- 356 micrograms/L/h). After three month testosterone therapy, in HP the GH responses to GHRH alone (1352 +/- 612 micrograms/L/h) and combined with PD (1948 +/- 616 microgram/L/h) were unchanged. Also IGF-I levels in HP were similar to those in NS (222 +/- 42 vs 210.6 +/- 55.8 micrograms/L) and were unchanged during testosterone replacement (280 +/- 31 micrograms/L). As androgens have been reported to modulate sympathoadrenal activity in the rat, both before and during testosterone replacement, we also measured plasma catecholamine levels. Basal NE (p < 0.05) but not E levels were lower in HP than in NS; testosterone restored basal NE levels to normal without affecting basal E. delta absolute increase of NE and E (p < 0.05 and 0.01 vs baseline, respectively) after PD in HP were similar to those in NS and were unchanged during testosterone replacement. In conclusion, these results demonstrate that the GH releasable pool is preserved in male hypogonadism. As in this condition a reduction of spontaneous GH secretion has been reported, it could be due to neurosecretory dysfunction but not to pituitary impairment. Subtle alterations of sympathoadrenal activity seem to be present in male hypogonadism and reversed by testosterone replacement.