Significant role of estrogen in maintaining cardiac mitochondrial functions

Oral hormonal contraceptives and cardiovascular risks in females

Oral hormonal contraception (OHC) is a widely employed method in females for the prevention of unintended pregnancies, as well as for the treatment of menstrual disorders, endometriosis, and polycystic ovarian syndrome. However, it is believed that with OHCs use, some females may have higher risk of cardiovascular diseases, such as hypertension, diabetes, myocardial infarction, thrombosis, and heart failure. Although such risks are infrequently detected in healthy young females with the use of oral contraceptives, slightly elevated risks of cardiovascular diseases have been observed among reproductive-aged healthy females. However, prolonged use of OHC has also been claimed to have protective cardiac effects and may contribute to reduced risk of cardiovascular disease. In fact, the debate on whether OHC administration increases the risk of cardiovascular diseases has been ongoing with inconsistent and controversial viewpoints. Nevertheless, a great deal of work has been carried out to understand the relationship between OHC use and the occurrence of cardiovascular risk in females who use OHC for preventing the unwanted pregnancy or treatment of other disorders. Therefore, in this review we summarize the most recent available evidence regarding the association between the use of oral hormonal contraceptives and the risk for cardiovascular disease in females who are using OHC to prevent unintended pregnancy.

Understanding the Role of Sex Hormones in Cardiovascular Kidney Metabolic Syndrome: Toward Personalized Therapeutic Approaches

Cardiovascular kidney metabolic (CKM) syndrome represents a complex interplay of cardiovascular disease (CVD), chronic kidney disease (CKD), and metabolic comorbidities, posing a significant public health challenge. Gender exerts a critical influence on CKM syndrome, affecting the disease severity and onset through intricate interactions involving sex hormones and key physiological pathways such as the renin-angiotensin system, oxidative stress, inflammation, vascular disease and insulin resistance. It is widely known that beyond the contribution of traditional risk factors, men and women exhibit significant differences in CKM syndrome and its components, with distinct patterns observed in premenopausal women and postmenopausal women compared to men. Despite women generally experiencing a lower incidence of CVD, their outcomes following cardiovascular events are often worse compared to men. The disparities also extend to the treatment approaches for kidney failure, with a higher prevalence of dialysis among men despite women exhibiting higher rates of CKD. The impact of endogenous sex hormones, the correlations between CKM and its components, as well as the long-term effects of treatment modalities using sex hormones, including hormone replacement therapies and gender-affirming therapies, have drawn attention to this topic. Current research on CKM syndrome is hindered by the scarcity of large-scale studies and insufficient integration of gender-specific considerations into treatment strategies. The underlying mechanisms driving the gender disparities in the pathogenesis of CKM syndrome, including the roles of estrogen, progesterone and testosterone derivatives, remain poorly understood, thus limiting their application in personalized therapeutic interventions. This review synthesizes existing knowledge to clarify the intricate relationship between sex hormones, gender disparities, and the progression of CVD within CKM syndrome. By addressing these knowledge gaps, this study aims to guide future research efforts and promote tailored approaches for effectively managing CKD syndrome.

Phytocompounds from Amazonian Plant Species against Acute Kidney Injury: Potential Nephroprotective Effects

There are several Amazonian plant species with potential pharmacological validation for the treatment of acute kidney injury, a condition in which the kidneys are unable to adequately filter the blood, resulting in the accumulation of toxins and waste in the body. Scientific production on plant compounds capable of preventing or attenuating acute kidney injury-caused by several factors, including ischemia, toxins, and inflammation-has shown promising results in animal models of acute kidney injury and some preliminary studies in humans. Despite the popular use of Amazonian plant species for kidney disorders, further pharmacological studies are needed to identify active compounds and subsequently conduct more complex preclinical trials. This article is a brief review of phytocompounds with potential nephroprotective effects against acute kidney injury (AKI). The classes of Amazonian plant compounds with significant biological activity most evident in the consulted literature were alkaloids, flavonoids, tannins, steroids, and terpenoids. An expressive phytochemical and pharmacological relevance of the studied species was identified, although with insufficiently explored potential, mainly in the face of AKI, a clinical condition with high morbidity and mortality.

Impact of Prenatal Exposure to Maternal Diabetes and High-Fat Diet on Postnatal Myocardial Ketone Body Metabolism in Rats

Infants exposed to diabetic pregnancy are at higher risk of cardiomyopathy at birth and early onset cardiovascular disease (CVD) as adults. Using a rat model, we showed how fetal exposure to maternal diabetes causes cardiac disease through fuel-mediated mitochondrial dysfunction, and that a maternal high-fat diet (HFD) exaggerates the risk. Diabetic pregnancy increases circulating maternal ketones which can have a cardioprotective effect, but whether diabetes-mediated complex I dysfunction impairs myocardial metabolism of ketones postnatally remains unknown. The objective of this study was to determine whether neonatal rat cardiomyocytes (NRCM) from diabetes- and HFD-exposed offspring oxidize ketones as an alternative fuel source. To test our hypothesis, we developed a novel ketone stress test (KST) using extracellular flux analyses to compare real-time ß-hydroxybutyrate (βHOB) metabolism in NRCM. We also compared myocardial expression of genes responsible for ketone and lipid metabolism. NRCM had a dose-dependent increase in respiration with increasing concentrations of βHOB, demonstrating that both control and combination exposed NRCM can metabolize ketones postnatally. Ketone treatment also enhanced the glycolytic capacity of combination exposed NRCM with a dose-dependent increase in the glucose-mediated proton efflux rate (PER) from CO2 (aerobic glycolysis) alongside a decreased reliance on PER from lactate (anaerobic glycolysis). Expression of genes responsible for ketone body metabolism was higher in combination exposed males. Findings demonstrate that myocardial ketone body metabolism is preserved and improves fuel flexibility in NRCM from diabetes- and HFD-exposed offspring, which suggests that ketones might serve a protective role in neonatal cardiomyopathy due to maternal diabetes.

Cardio-Metabolic Health and HRT in Menopause: Novel Insights in Mitochondrial Biogenesis and RAAS

Recent evidence shows the cardiometabolic effects of estrogen administration in postmenopausal women. Women have a cardiometabolic advantage during their reproductive years, which is lost at menopause due to declining estradiol (E2). E2, also known as 17-beta-estradiol, has diverse effects in its target tissues, including the cardiovascular (CV) system, through genomic and non-genomic signaling. Metabolic changes characteristic of menopause include a worsening lipid profile, changes in body fat distribution, epicardial and pericardial fat deposition, increased susceptibility to weight gain, and increased blood pressure, resulting in an increased risk of accelerated cardiovascular disease (CVD) development. E2 mediates its cardioprotective actions by increasing mitochondrial biogenesis, angiogenesis, and vasodilation, decreasing reactive oxygen species (ROS) and oxidative stress, and modulating the renin-angiotensin-aldosterone system (RAAS). In this review, we assess whether it is prudent to develop an approach to managing postmenopausal women based on modifying the patient's CV risk that includes human-identical hormone replacement therapy (HRT), modulation of RAAS, and stimulating mitochondrial biogenesis. Further research is needed to assess the safety and benefit of HRT to reduce cardiometabolic risk.

Colon specific delivery of miR-155 inhibitor alleviates estrogen deficiency related phenotype via microbiota remodeling

Compelling data have indicated menopause-associated increase in cardiovascular disease in women, while the underlying mechanisms remain largely unknown. It is established that changes of intestinal microbiota affect cardiovascular function in the context of metabolic syndrome. We here aimed to explore the possible link between host intestinal function, microbiota, and cardiac function in the ovariectomy (OVX) mouse model. Mice were ovariectomized to induce estrogen-related metabolic syndrome and cardiovascular defect. Microbiota was analyzed by 16s rRNA sequencing. miRNA and mRNA candidates expression were tested by qPCR. Cardiac function was examined by echocardiography. Colon specific delivery of miRNA candidates was achieved by oral gavage of Eudragit S100 functionalized microspheres. In comparison with the sham-operated group, OVX mice showed compromised cardiac function, together with activated inflammation in the visceral adipose tissue and heart. Lactobacillus abundance was significantly decreased in the gut of OVX mice. Meanwhile, miR-155 was mostly upregulated in the intestinal epithelium and thus the feces over other candidates, which in turn decreased Lactobacillus abundance in the intestine when endocytosed. Oral delivery of miR-155 antagonist restored the protective microbiota and thus protected the cardiac function in the OVX mice. This study has established a possible regulatory axis of intestinal miRNAs-microbiota-estrogen deficiency related phenotype in the OVX model. Colon specific delivery of therapeutic miRNAs would possibly restore the microbiota toward protective phenotype in the context of metabolic syndrome.

Estrogen signaling as a bridge between the nucleus and mitochondria in cardiovascular diseases

Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide. Epidemiological studies indicate that pre-menopausal women are more protected against the development of CVDs compared to men of the same age. This effect is attributed to the action/effects of sex steroid hormones on the cardiovascular system. In this context, estrogen modulates cardiovascular function in physiological and pathological conditions, being one of the main physiological cardioprotective agents. Here we describe the common pathways and mechanisms by which estrogens modulate the retrograde and anterograde communication between the nucleus and mitochondria, highlighting the role of genomic and non-genomic pathways mediated by estrogen receptors. Additionally, we discuss the presumable role of bromodomain-containing protein 4 (BRD4) in enhancing mitochondrial biogenesis and function in different CVD models and how this protein could act as a master regulator of estrogen protective activity. Altogether, this review focuses on estrogenic control in gene expression and molecular pathways, how this activity governs nucleus-mitochondria communication, and its projection for a future generation of strategies in CVDs treatment.

Sex Steroid Receptors in Polycystic Ovary Syndrome and Endometriosis: Insights from Laboratory Studies to Clinical Trials

Polycystic ovary syndrome (PCOS) and endometriosis are reproductive disorders that may cause infertility. The pathology of both diseases has been suggested to be associated with sex steroid hormone receptors, including oestrogen receptors (ER), progesterone receptors (PRs) and androgen receptors (ARs). Therefore, with this review, we aim to provide an update on the available knowledge of these receptors and how their interactions contribute to the pathogenesis of PCOS and endometriosis. One of the main PCOS-related medical conditions is abnormal folliculogenesis, which is associated with the downregulation of ER and AR expression in the ovaries. In addition, metabolic disorders in PCOS are caused by dysregulation of sex steroid hormone receptor expression. Furthermore, endometriosis is related to the upregulation of ER and the downregulation of PR expression. These receptors may serve as therapeutic targets for the treatment of PCOS-related disorders and endometriosis, considering their pathophysiological roles. Receptor agonists may be applied to increase the expression of a specific receptor and treat endometriosis or metabolic disorders. In contrast, receptor antagonist functions to reduce receptor expression and can be used to treat endometriosis and induce ovulation. Understanding PCOS and the pathological roles of endometriosis sex steroid receptors is crucial for developing potential therapeutic strategies to treat infertility in both conditions. Therefore, research should be continued to fill the knowledge gap regarding the subject.

Evaluation of the Interaction of Sex Hormones and Cardiovascular Function and Health

Purpose of Review

Sex hormones drive development and function of reproductive organs or the development of secondary sex characteristics but their effects on the cardiovascular system are poorly understood. In this review, we identify the gaps in our understanding of the interaction between sex hormones and the cardiovascular system.

Recent Findings

Studies are progressively elucidating molecular functions of sex hormones in specific cell types in parallel with the initiation of crucial large randomized controlled trials aimed at improving therapies for cardiovascular diseases (CVDs) associated with aberrant levels of sex hormones.

Summary

In contrast with historical assumptions, we now understand that men and women show different symptoms and progression of CVDs. Abnormal levels of sex hormones pose an independent risk for CVD, which is apparent in conditions like Klinefelter syndrome, androgen insensitivity syndrome, and menopause. Moreover, sex hormone–based therapies remain understudied and may not be beneficial for cardiovascular health.

Sex-related differences of early cardiac functional and proteomic alterations in a rat model of myocardial ischemia

BACKGROUND

Reduced cardiovascular risk in premenopausal women has been the focus of research in recent decades. Previous hypothesis-driven experiments have highlighted the role of sex hormones on distinct inflammatory responses, mitochondrial proteins, extracellular remodeling and estrogen-mediated cardioprotective signaling pathways related to post-ischemic recovery, which were associated with better cardiac functional outcomes in females. We aimed to investigate the early, sex-specific functional and proteomic changes following myocardial ischemia in an unbiased approach.

METHODS

Ischemia was induced in male (M-Isch) and female (F-Isch) rats with sc. injection of isoproterenol (85 mg/kg) daily for 2 days, while controls (M-Co, F-Co) received sc. saline solution. At 48 h after the first injection pressure-volume analysis was carried out to assess left ventricular function. FFPE tissue slides were scanned and analyzed digitally, while myocardial proteins were quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) using isobaric labeling. Concentrations of circulating steroid hormones were measured with LC-MS/MS. Feature selection (PLS and PLS-DA) was used to examine associations among functional, proteomic and hormonal datasets.

RESULTS

Induction of ischemia resulted in 38% vs 17% mortality in M-Isch and F-Isch respectively. The extent of ischemic damage to surviving rats was comparable between the sexes. Systolic dysfunction was more pronounced in males, while females developed a more severe impairment of diastolic function. 2224 proteins were quantified, with 520 showing sex-specific differential regulation. Our analysis identified transcriptional, cytoskeletal, contractile, and mitochondrial proteins, molecular chaperones and the extracellular matrix as sources of disparity between the sexes. Bioinformatics highlighted possible associations of estrogens and their metabolites with early functional and proteomic alterations.

CONCLUSIONS

Our study has highlighted sex-specific alterations in systolic and diastolic function shortly after ischemia, and provided a comprehensive look at the underlying proteomic changes and the influence of estrogens and their metabolites. According to our bioinformatic analysis, inflammatory, mitochondrial, chaperone, cytoskeletal, extracellular and matricellular proteins are major sources of intersex disparity, and may be promising targets for early sex-specific pharmacologic interventions.

Sexual dimorphism in cardiac remodeling: the molecular mechanisms ruled by sex hormones in the heart

Heart failure (HF) is growing in prevalence, due to an increase in aging and comorbidities. Heart failure with reduced ejection fraction (HFrEF) is more common in men, whereas heart failure with preserved ejection fraction (HFpEF) has a higher prevalence in women. However, the reasons for these epidemiological trends are not clear yet. Since HFpEF affects mostly postmenopausal women, sex hormones should play a pivotal role in HFpEF development. Furthermore, for HFpEF, contrary to HFrEF, effective therapeutic approaches are missing. Interestingly, studies evidenced that some therapies can have better results in women than in HFpEF men, emphasizing the necessity of understanding these observations at a molecular level. Thus, herein, we review the molecular mechanisms of estrogen and androgen actions in the heart in physiological conditions and explain how its dysregulation can lead to disease development. This clarification is essential in the road for an effective personalized management of HF, particularly HFpEF, towards the development of sex-specific therapeutic approaches.

A framework for developing sex-specific engineered heart models

The convergence of tissue engineering and patient-specific stem cell biology has enabled the engineering of in vitro tissue models that allow the study of patient-tailored treatment modalities. However, sex-related disparities in health and disease, from systemic hormonal influences to cellular-level differences, are often overlooked in stem cell biology, tissue engineering and preclinical screening. The cardiovascular system, in particular, shows considerable sex-related differences, which need to be considered in cardiac tissue engineering. In this Review, we analyse sex-related properties of the heart muscle in the context of health and disease, and discuss a framework for including sex-based differences in human cardiac tissue engineering. We highlight how sex-based features can be implemented at the cellular and tissue levels, and how sex-specific cardiac models could advance the study of cardiovascular diseases. Finally, we define design criteria for sex-specific cardiac tissue engineering and provide an outlook to future research possibilities beyond the cardiovascular system.

Predominance of Heart Failure With Preserved Ejection Fraction in Postmenopausal Women: Intra- and Extra-Cardiomyocyte Maladaptive Alterations Scaffolded by Estrogen Deficiency

Heart failure (HF) remains a public health concern as it is associated with high morbidity and death rates. In particular, heart failure with preserved ejection fraction (HFpEF) represents the dominant (>50%) form of HF and mostly occurring among postmenopausal women. Hence, the initiation and progression of the left ventricular diastolic dysfunctions (LVDD) (a typically clinical manifestation of HFpEF) in postmenopausal women have been attributed to estrogen deficiency and the loss of its residue cardioprotective effects. In this review, from a pathophysiological and immunological standpoint, we discuss the probable multiple pathomechanisms resulting in HFpEF, which are facilitated by estrogen deficiency. The initial discussions recap estrogen and estrogen receptors (ERs) and β-adrenergic receptors (βARs) signaling under physiological/pathological states to facilitate cardiac function/dysfunction, respectively. By reconciling these prior discussions, attempts were made to explain how the loss of estrogen facilitates the disruptions both ERs and βARs-mediated signaling responsible for; the modulation of intra-cardiomyocyte calcium homeostasis, maintenance of cardiomyocyte cytoskeletal and extracellular matrix, the adaptive regulation of coronary microvascular endothelial functions and myocardial inflammatory responses. By scaffolding the disruption of these crucial intra- and extra-cardiomyocyte physiological functions, estrogen deficiency has been demonstrated to cause LVDD and increase the incidence of HFpEF in postmenopausal women. Finally, updates on the advancements in treatment interventions for the prevention of HFpEF were highlighted.

Evaluating the effects of carbon monoxide releasing molecule-2 against myocardial ischemia-reperfusion injury in ovariectomized female rats

PURPOSE

Cardioprotective effect of carbon monoxide, a gasotransmitter against myocardial ischemia-reperfusion injury (I/R), is well established in preclinical studies with male rats. However, its ischemic tolerance in post-menopausal animals has not been examined due to functional perturbations at the cellular level.

METHODS

The protective role of carbon monoxide releasing molecule-2 (CORM-2) on myocardial I/R was studied in female Wistar rats using the Langendorff apparatus. The animals were randomly divided into normal and ovariectomized (Ovx) female rats and were maintained 2 months post-surgery. Each group was further divided into 4 subgroups (n = 6/subgroup): normal, I/R, CORM-2-control (20 μmol/L), and CORM-2-I/R. The cardiac injury was estimated via myocardial infarct size, lactate dehydrogenase, and creatine kinase levels in coronary effluent and cardiac hemodynamic indices. Mitochondrial functional activity was assessed by measuring mitochondrial electron transport chain enzyme activities, swelling behavior, mitochondrial membrane potential, and oxidative stress.

RESULTS

Hemodynamic indices were significantly lower in ovariectomized rat hearts than in normal rat hearts. Sixty minutes of reperfusion of ischemic heart exhibited deteriorated cardiac physiological recovery in both ovariectomized and normal groups, where prominent decline was observed in ovariectomized rat. However, preconditioning the isolated heart with CORM-2 improved hemodynamics parameters significantly in both ovariectomized and normal rat hearts challenged with I/R, but with a limited degree of protection in ovariectomized rat hearts. The protective effect of CORM-2 was further confirmed via a reduction in cardiac injury, preservation of mitochondrial enzymes, and reduction in oxidative stress in all groups.

CONCLUSION

CORM-2 administration significantly attenuated myocardial I/R injury in ovariectomized rat hearts by attenuating I/R-associated mitochondrial perturbations and reducing oxidative stress.

Sirtuin 1, Visfatin and IL-27 Serum Levels of Type 1 Diabetic Females in Relation to Cardiovascular Parameters and Autoimmune Thyroid Disease

The loss of cardioprotection observed in premenopausal, diabetic women may result from the interplay between epigenetic, metabolic, and immunological factors. The aim of this study was to evaluate the concentration of sirtuin 1, visfatin, and IL-27 in relation to cardiovascular parameters and Hashimoto’s disease (HD) in young, asymptomatic women with type 1 diabetes mellitus (T1DM). Thyroid ultrasound, carotid intima-media thickness (cIMT) measurement, electrocardiography, and echocardiography were performed in 50 euthyroid females with T1DM (28 with HD and 22 without concomitant diseases) and 30 controls. The concentrations of serum sirtuin 1, visfatin and IL-27 were assessed using ELISA. The T1DM and HD group had higher cIMT (p = 0.018) and lower left ventricular global longitudinal strain (p = 0.025) compared to females with T1DM exclusively. In women with a double diagnosis, the sirtuin 1 and IL-27 concentrations were non-significantly higher than in other groups and significantly positively correlated with each other (r = 0.445, p = 0.018) and thyroid volume (r = 0.511, p = 0.005; r = 0.482, p = 0.009, respectively) and negatively correlated with relative wall thickness (r = –0.451, p = 0.016; r = –0.387, p = 0.041, respectively). These relationships were not observed in the control group nor for the visfatin concentration. These results suggest that sirtuin 1 and IL-27 contribute to the pathogenesis of early cardiac dysfunction in women with T1DM and HD.

Mineralocorticoid receptor blockade with finerenone improves heart function and exercise capacity in ovariectomized mice

AIMS

In post-menopausal women, incidence of heart failure with preserved ejection fraction is higher than in men. Hormonal replacement therapies did not demonstrate benefits. We tested whether the non-steroidal mineralocorticoid receptor antagonist finerenone limits the progression of heart failure in ovariectomized (OVX) mice with metabolic disorders.

METHODS AND RESULTS

Ovariectomy was performed in 4-month-old mice, treated or not at 7 months old for 1 month with finerenone (Fine) 1 mg/kg/day. Left ventricular (LV) cardiac and coronary endothelial functions were assessed by echocardiography, catheterization, and myography. Blood pressure was measured by plethysmography. Insulin and glucose tolerance tests were performed. Exercise capacity and spontaneous activity were measured on treadmill and in combined indirect calorimetric cages equipped with voluntary running wheel. OVX mice presented LV diastolic dysfunction without modification of ejection fraction compared with controls (CTL), whereas finerenone improved LV filling pressure (LV end-diastolic pressure, mmHg: CTL 3.48 ± 0.41, OVX 6.17 ± 0.30**, OVX + Fine 3.65 ± 0.55† , **P < 0.01 vs. CTL, † P < 0.05 vs. OVX) and compliance (LV end-diastolic pressure-volume relation, mmHg/RVU: CTL 1.65 ± 0.42, OVX 4.77 ± 0.37***, OVX + Fine 2.87 ± 0.26†† , ***P < 0.001 vs. CTL, †† P < 0.01 vs. OVX). Acetylcholine-induced endothelial-dependent relaxation of coronary arteries was impaired in ovariectomized mice and improved by finerenone (relaxation, %: CTL 86 ± 8, OVX 38 ± 3**, OVX + Fine 83 ± 7†† , **P < 0.01 vs. CTL, †† P < 0.01 vs. OVX). Finerenone improved decreased ATP production by subsarcolemmal mitochondria after ovariectomy. Weight gain, increased blood pressure, and decreased insulin and glucose tolerance in OVX mice were improved by finerenone. The exercise capacity at race was diminished in untreated OVX mice only. Spontaneous activity measurements in ovariectomized mice showed decreased horizontal movements, reduced time spent in a running wheel, and reduced VO2 and VCO2 , all parameters improved by finerenone.

CONCLUSIONS

Finerenone improved cardiovascular dysfunction and exercise capacity after ovariectomy-induced LV diastolic dysfunction with preserved ejection fraction.

Deficit of female sex hormones desensitizes rat cardiac mitophagy

Long-term deprivation of female sex hormones has been shown to mediate accumulation of damaged mitochondria in ventricular muscle leading to cardiovascular dysfunction. Therefore, the roles of female sex hormones in mitochondrial quality control are closely focused. In the present study, depletion of female sex hormones impairing mitochondrial autophagy in the heart was hypothesized. Cardiac mitophagy was therefore investigated in the heart of 10-week ovariectomized (OVX) and sham-operated (SHAM) rats. By using isolated mitochondria preparation, results demonstrated an increase in mitochondrial PTEN-induced kinase 1 accumulation in the sample of OVX rats indicating mitochondrial outer membrane dysfunction. However, no change in p62 and LC3-II translocation to mitochondria was observed between two groups indicating unresponsiveness of mitophagosome formation in the OVX rat heart. This loss might be resulted from significant decreases in Parkin and Bcl2l13 expression, but not Bnip3 activation. In summary, results suggest that mitochondrial abnormality in the heart after deprivation of female sex hormones could consequently be due to desensitization of mitophagy process.

Diminished substrate-mediated cardiac mitochondrial respiration and elevated autophagy in adult male offspring of gestational diabetic rats

Heart diseases are common in the offspring of diabetic mother (ODM). Defects in mitochondrial metabolism and autophagy may, in part, be responsible for the adverse structural and functional alterations in the heart. The principal objective of this study was to investigate cardiac mitochondrial respiration and autophagy in male and female offspring of diabetic pregnancy at two different developmental stages of life, weaning and adult. Male and female offspring of rats with streptozotocin-induced gestational diabetes were used for the study and compared with offspring of control (non-diabetic) mother (OCM) rats. High-resolution respirometry was used to measure substrate-mediated respiration in mitochondria isolated from ventricular tissues of ODM and OCM. Expression of proteins associated with autophagy and oxidative stress was examined by western blot analysis. Mitochondrial complex I and complex II respiration was significantly reduced in adult male ODM while it was unaltered or less affected in weaning male, adult and weaning female ODM. Elevated autophagy was observed in adult male but not in adult female ODM. Expression of oxidative stress markers was observed to be similar in all the groups. Altered cardiac mitochondrial respiration and autophagy were observed in adult male ODM compared to OCM, while the male and female offspring at weaning stage were less affected. The results of the study show that maternal hyperglycemia affects mitochondrial respiration and autophagy in the ODM heart, which may potentially be responsible for the cardiovascular complications observed in adult life.

Improvement in cardiac function of ovariectomized rats by antioxidant tempol

A rise in heart disease incidence in women after menopause has led to investigations into the role of female sex hormones on cardiac function. Although various adverse changes in cardiac contractile function following loss of female sex hormones have been reported, a clear mechanism of action has never been characterized. In order to examine whether an elevation in oxidative stress is a major cause of cardiac contractile dysfunction after female sex hormone deprivation, cardiac functions of ovariectomized rats with and without supplementation of superoxide scavenger tempol were compared to those of sham-operated controls. Chronic deprivation of female sex hormones reduced total oxidative capacity and increased plasma carbonyl protein content. Tempol supplementation of ovariectomized rats significantly ameliorated plasma oxidative stress status. Echocardiography demonstrated a significant decrease in left ventricular ejection fraction in ovariectomized rats, which was completely prevented by tempol supplementation. Decreased myocardial contractility occurs with reduced maximum myofilament force of contraction and amplitude of transient intracellular Ca²⁺ concentration, both phenomena completely attenuated by tempol supplementation. However, tempol only partially prevented shift of heart myosin heavy chain from dominant α-to β-isoform of ovariectomized rats. Immunoblot analysis of protein carbonylation indicated that tempol supplementation significantly reduced the level of cardiac myofibrillar proteins oxidation increased in ovariectomized rat heart. Taken together, the results indicate changes of cardiac contractile machinery following loss of female sex hormones were, in part, due to an increase in oxidative stress, and antioxidant supplementation could be considered another potential prevention measure in postmenopausal women.

Age and Sex Influence Mitochondria and Cardiac Health in Offspring Exposed to Maternal Glucolipotoxicity

Infants of diabetic mothers are at risk of cardiomyopathy at birth and myocardial infarction in adulthood, but prevention is hindered because mechanisms remain unknown. We previously showed that maternal glucolipotoxicity increases the risk of cardiomyopathy and mortality in newborn rats through fuel-mediated mitochondrial dysfunction. Here we demonstrate ongoing cardiometabolic consequences by cross-fostering and following echocardiography, cardiomyocyte bioenergetics, mitochondria-mediated turnover, and cell death following metabolic stress in aged adults. Like humans, cardiac function improves by weaning with no apparent differences in early adulthood but declines again in aged diabetes-exposed offspring. This is preceded by impaired oxidative phosphorylation, exaggerated age-related increase in mitochondrial number, and higher oxygen consumption. Prenatally exposed male cardiomyocytes have more mitolysosomes indicating high baseline turnover; when exposed to metabolic stress, mitophagy cannot increase and cardiomyocytes have faster mitochondrial membrane potential loss and mitochondria-mediated cell death. Details highlight age- and sex-specific roles of mitochondria in developmentally programmed adult heart disease.

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Fetal exposures disrupt mitochondria, bioenergetics, & cardiac function at birth

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First, bioenergetics & function improve until greater reliance on OXPHOS with age

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At 6MO, poor respiration incites biogenesis & mitophagy, and then functional decline

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Fetal exposures cause faster mitochondria-mediated cell death in aged adult hearts

Sex differences in inflammation, redox biology, mitochondria and autoimmunity

Autoimmune diseases are characterized by circulating antibodies and immune complexes directed against self-tissues that result in both systemic and organ-specific inflammation and pathology. Most autoimmune diseases occur more often in women than men. One exception is myocarditis, which is an inflammation of the myocardium that is typically caused by viral infections. Sex differences in the immune response and the role of the sex hormones estrogen and testosterone are well established based on animal models of autoimmune viral myocarditis as well as in mitochondrial function leading to reactive oxygen species production. RNA viruses like coxsackievirus B3, the primary cause of myocarditis in the US, activate the inflammasome through mitochondrial antiviral signaling protein located on the mitochondrial outer membrane. Toll-like receptor 4 and the inflammasome are the primary signaling pathways that increase inflammation during myocarditis, which is increased by testosterone. This review describes what is known about sex differences in inflammation, redox biology and mitochondrial function in the male-dominant autoimmune disease myocarditis and highlights gaps in the literature and future directions.

Comparison of exercise training and estrogen supplementation on mast cell-mediated doxorubicin-induced cardiotoxicity

Cardiac inflammation has been proposed as one of the primary mechanisms of anthracycline-induced acute cardiotoxicity. A reduction in cardiac inflammation might also reduce cardiotoxicity. This study aimed to evaluate the potential of estrogen therapy and regular exercise on attenuating cardiac inflammation in the context of doxorubicin-induced cardiomyopathy. Ovariectomized rats were randomly allocated into estrogen supplementation, exercise training, and mast cell stabilizer treatment groups. Eight weeks after ovariectomy, rats received six cumulative doses of doxorubicin for two weeks. Echocardiography demonstrated a progressive decrease in ejection fraction in doxorubicin-treated rats without hypertrophic effect. This systolic defect was completely prevented by either estrogen supplementation or mast cell stabilizer treatment but not by regular exercise. As a heart disease indicator, increased β-myosin heavy chain expression induced by doxorubicin could only be prevented by estrogen supplementation. Decrease in shortening and intracellular Ca²⁺ transients of cardiomyocytes were due to absence of female sex hormones without further effects of doxorubicin. Again, estrogen supplementation and mast cell stabilizer treatment prevented these changes but exercise training did not. Histological analysis indicated that the hyperactivation of cardiac mast cells in ovariectomized rats was augmented by doxorubicin. Estrogen supplementation and mast cell stabilizer treatment completely prevented both increases in mast cell density and degranulation, whereas exercise training partially attenuated the hyperactivation. Our results, therefore, suggest that estrogen supplementation acts similarly to mast cell stabilizers in attenuating the effects of doxorubicin. Ineffectiveness of regular exercise in preventing the acute cardiotoxicity of doxorubicin might be due to a lesser effect on preventing cardiac inflammation.

Exploring mechanisms of increased cardiovascular disease risk with antipsychotic medications: Risperidone alters the cardiac proteomic signature in mice

Atypical antipsychotic (AA) medications including risperidone (RIS) and olanzapine (OLAN) are FDA approved for the treatment of psychiatric disorders including schizophrenia, bipolar disorder and depression. Clinical side effects of AA medications include obesity, insulin resistance, dyslipidemia, hypertension and increased cardiovascular disease risk. Despite the known pharmacology of these AA medications, the mechanisms contributing to adverse metabolic side-effects are not well understood. To evaluate drug-associated effects on the heart, we assessed changes in the cardiac proteomic signature in mice administered for 4 weeks with clinically relevant exposure of RIS or OLAN. Using proteomic and gene enrichment analysis, we identified differentially expressed (DE) proteins in both RIS- and OLAN-treated mouse hearts (p < 0.05), including proteins comprising mitochondrial respiratory complex I and pathways involved in mitochondrial function and oxidative phosphorylation. A subset of DE proteins identified were further validated by both western blotting and quantitative real-time PCR. Histological evaluation of hearts indicated that AA-associated aberrant cardiac gene expression occurs prior to the onset of gross pathomorphological changes. Additionally, RIS treatment altered cardiac mitochondrial oxygen consumption and whole body energy expenditure. Our study provides insight into the mechanisms underlying increased patient risk for adverse cardiac outcomes with chronic treatment of AA medications.

Sex differences in cardiometabolic disorders

The prevalence of cardiometabolic disorders in both women and men has increased worldwide and is linked to a rise in obesity and obesity-associated associated clustering of other cardiometabolic risk factors such as hypertension, impaired glucose regulation and dyslipidemia. However, the predominance of common types of cardiometabolic disorders such as heart failure, atrial fibrillation and ischemic heart disease is sex specific, and our identification of these and the underlying mechanisms is only just emerging. New evidence suggests that sex hormones, sex-specific molecular mechanisms and gender influence glucose and lipid metabolisms, as well as cardiac energy metabolism, and function. Here we review sex differences in cardiometabolic risk factors, associated preclinical and clinical cardiac disorders and potential therapeutic avenues.

Mitochondrial quality control mechanisms as molecular targets in cardiac ageing

Cardiovascular disease is the leading cause of morbidity and mortality worldwide. Advancing age is a major risk factor for developing cardiovascular disease because of the lifelong exposure to cardiovascular risk factors and specific alterations affecting the heart and the vasculature during ageing. Indeed, the ageing heart is characterized by structural and functional changes that are caused by alterations in fundamental cardiomyocyte functions. In particular, the myocardium is heavily dependent on mitochondrial oxidative metabolism and is especially susceptible to mitochondrial dysfunction. Indeed, primary alterations in mitochondrial function, which are subsequently amplified by defective quality control mechanisms, are considered to be major contributing factors to cardiac senescence. In this Review, we discuss the mechanisms linking defective mitochondrial quality control mechanisms (that is, proteostasis, biogenesis, dynamics, and autophagy) to organelle dysfunction in the context of cardiac ageing. We also illustrate relevant molecular pathways that might be exploited for the prevention and treatment of age-related heart dysfunction.

Oceans as a Source of Immunotherapy

Marine flora is taxonomically diverse, biologically active, and chemically unique. It is an excellent resource, which offers great opportunities for the discovery of new biopharmaceuticals such as immunomodulators and drugs targeting cancerous, inflammatory, microbial, and fungal diseases. The ability of some marine molecules to mediate specific inhibitory activities has been demonstrated in a range of cellular processes, including apoptosis, angiogenesis, and cell migration and adhesion. Immunomodulators have been shown to have significant therapeutic effects on immune-mediated diseases, but the search for safe and effective immunotherapies for other diseases such as sinusitis, atopic dermatitis, rheumatoid arthritis, asthma and allergies is ongoing. This review focuses on the marine-originated bioactive molecules with immunomodulatory potential, with a particular focus on the molecular mechanisms of specific agents with respect to their targets. It also addresses the commercial utilization of these compounds for possible drug improvement using metabolic engineering and genomics.

Estrogen but not testosterone preserves myofilament function from doxorubicin-induced cardiotoxicity by reducing oxidative modifications

Here, we aimed to explore sex differences and the impact of sex hormones on cardiac contractile properties in doxorubicin (DOX)-induced cardiotoxicity. Male and female Sprague-Dawley rats were subjected to sham surgery or gonadectomy and then treated or untreated with DOX (2 mg/kg) every other week for 10 wk. Estrogen preserved maximum active tension (T_max) with DOX exposure, whereas progesterone and testosterone did not. The effects of sex hormones and DOX correlated with both altered myosin heavy chain isoform expression and myofilament protein oxidation, suggesting both as possible mechanisms. However, acute treatment with oxidative stress (H₂O₂) or a reducing agent (DTT) indicated that the effects on T_max were mediated by reversible myofilament oxidative modifications and not only changes in myosin heavy chain isoforms. There were also sex differences in the DOX impact on myofilament Ca²⁺ sensitivity. DOX increased Ca²⁺ sensitivity in male rats only in the absence of testosterone and in female rats only in the presence of estrogen. Conversely, DOX decreased Ca²⁺ sensitivity in female rats in the absence of estrogen. In most instances, this mechanism was through altered phosphorylation of troponin I at Ser²³/Ser²⁴. However, there was an additional DOX-induced, estrogen-dependent, irreversible (by DTT) mechanism that altered Ca²⁺ sensitivity. Our data demonstrate sex differences in cardiac contractile responses to chronic DOX treatment. We conclude that estrogen protects against chronic DOX treatment in the heart, preserving myofilament function. NEW & NOTEWORTHY We identified sex differences in cardiotoxic effects of chronic doxorubicin (DOX) exposure on myofilament function. Estrogen, but not testosterone, decreases DOX-induced oxidative modifications on myofilaments to preserve maximum active tension. In rats, DOX exposure increased Ca²⁺ sensitivity in the presence of estrogen but decreased Ca²⁺ sensitivity in the absence of estrogen. In male rats, the DOX-induced shift in Ca²⁺ sensitivity involved troponin I phosphorylation; in female rats, this was through an estrogen-dependent mechanism.

Endurance training restores spatially distinct cardiac mitochondrial function and myocardial contractility in ovariectomized rats

We previously demonstrated that the loss of female hormones induces cardiac and mitochondrial dysfunction in the female heart. Here, we show the impact of endurance training for twelve weeks, a nonpharmacological therapy against cardiovascular disease caused by ovariectomy and its contribution to cardiac contractility, mitochondrial quality control, bioenergetics and oxidative damage. We found that ovariectomy induced cardiac hypertrophy and dysfunction by decreasing SERCA2 and increasing phospholamban protein expression. Endurance training restored myocardial contractility, SERCA2 levels, increased calcium transient in ovariectomized rats but did not change phospholamban protein expression or cardiac hypertrophy. Additionally, ovariectomy decreased the amount of intermyofibrillar mitochondria and induced mitochondrial fragmentation that were accompanied by decreased levels of mitofusin 1, PGC-1α, NRF-1, total AMPK-α and mitochondrial Tfam. Endurance training prevented all these features except for mitofusin 1. Ovariectomy reduced O₂ consumption, elevated O₂^.- release and increased Ca²⁺-induced mitochondrial permeability transition pore opening in both mitochondrial subpopulations. Ovariectomy also increased NOX-4 protein expression in the heart, reduced mitochondrial Mn-SOD, catalase protein expression and increased protein carbonylation in both mitochondrial subpopulations, which were prevented by endurance training. Taken together, our findings show that endurance training prevented cardiac contractile dysfunction and mitochondrial quality control in ovariectomized rats.

Estrogens, Estrogen Receptors Effects on Cardiac and Skeletal Muscle Mitochondria

Mitochondria are unique organelles present in almost all cell types. They are involved not only in the supply of energy to the host cell, but also in multiple biochemical and biological processes like calcium homeostasis, production, and regulation of reactive oxygen species (ROS), pH control, or cell death. The importance of mitochondria in cell biology and pathology is increasingly recognized. Being maternally inherited, mitochondria exhibit a tissue-specificity, because most of the mitochondrial proteins are encoded by the nuclear genome. This renders them exquisitely well-adapted to the physiology of the host cell. It is thus not surprising that mitochondria show a sexual dimorphism and that they are also prone to the influence of sex chromosomes and sex hormones. Estrogens affect mitochondria through multiple processes involving membrane and nuclear estrogen receptors (ERs) as well as more direct effects. Moreover, estrogen receptors have been identified within mitochondria. The effects of estrogens on mitochondria comprise protein content and specific activity of mitochondrial proteins, phospholipid content of membranes, oxidant and anti-oxidant capacities, oxidative phosphorylation, and calcium retention capacities. Herein we will briefly review the life cycle and functions of mitochondria, the importance of estrogen receptors and the effects of estrogens on heart and skeletal muscle mitochondria.

Female Heart Health: Is GPER the Missing Link?

The G Protein-Coupled Estrogen Receptor (GPER) is a novel membrane-bound receptor that mediates non-genomic actions of the primary female sex hormone 17β-estradiol. Studies over the past two decades have elucidated the beneficial actions of this receptor in a number of cardiometabolic diseases. This review will focus specifically on the cardiac actions of GPER, since this receptor is expressed in cardiomyocytes as well as other cells within the heart and most likely contributes to estrogen-induced cardioprotection. Studies outlining the impact of GPER on diastolic function, mitochondrial function, left ventricular stiffness, calcium dynamics, cardiac inflammation, and aortic distensibility are discussed. In addition, recent data using genetic mouse models with global or cardiomyocyte-specific GPER gene deletion are highlighted. Since estrogen loss due to menopause in combination with chronological aging contributes to unique aspects of cardiac dysfunction in women, this receptor may provide novel therapeutic effects. While clinical studies are still required to fully understand the potential for pharmacological targeting of this receptor in postmenopausal women, this review will summarize the evidence gathered thus far on its likely beneficial effects.

Impact of 17β-estradiol on complex I kinetics and H2O2 production in liver and skeletal muscle mitochondria

Naturally or surgically induced postmenopausal women are widely prescribed estrogen therapies to alleviate symptoms associated with estrogen loss and to lower the subsequent risk of developing metabolic diseases, including diabetes and nonalcoholic fatty liver disease. However, the molecular mechanisms by which estrogens modulate metabolism across tissues remain ill-defined. We have previously reported that 17β-estradiol (E2) exerts antidiabetogenic effects in ovariectomized (OVX) mice by protecting mitochondrial and cellular redox function in skeletal muscle. The liver is another key tissue for glucose homeostasis and a target of E2 therapy. Thus, in the present study we determined the effects of acute loss of ovarian E2 and E2 administration on liver mitochondria. In contrast to skeletal muscle mitochondria, E2 depletion via OVX did not alter liver mitochondrial respiratory function or complex I (CI) specific activities (NADH oxidation, quinone reduction, and H2O2 production). Surprisingly, in vivo E2 replacement therapy and in vitro E2 exposure induced tissue-specific effects on both CI activity and on the rate and topology of CI H2O2 production. Overall, E2 therapy protected and restored the OVX-induced reduction in CI activity in skeletal muscle, whereas in liver mitochondria E2 increased CI H2O2 production and decreased ADP-stimulated respiratory capacity. These results offer novel insights into the tissue-specific effects of E2 on mitochondrial function.

Divergent Effects of Cyclophilin-D Inhibition on the Female Rat Heart: Acute Versus Chronic Post-Myocardial Infarction

BACKGROUND/AIMS

The mitochondrial permeability transition pore opening plays a critical role in the pathogenesis of myocardial infarction. Inhibition of cyclophilin-D (CyP-D), a key regulator of the mitochondrial permeability transition pore, has been shown to exert cardioprotective effects against ischemia-reperfusion injury on various animal models, mostly in males. However, failure of recent clinical trials requires a detailed elucidation of the cardioprotective efficacy of CyP-D inhibition. The aim of this study was to examine whether cardioprotective effects of sanglifehrin A, a potent inhibitor of CyP-D, on post-infarcted hearts depends on reperfusion.

METHODS

Acute or chronic myocardial infarction was induced by coronary artery ligation with/without subsequent reperfusion for 2 and 28 days in female Sprague-Dawley rats. Cardiac function was estimated by echocardiography. Oxygen consumption rates, ROS production, permeability transition pore opening, protein carbonylation and respiratory supercomplexes were analyzed in isolated cardiac mitochondria.

RESULTS

Sanglifehrin A significantly improved cardiac function of reperfused hearts at 2 days but failed to protect after 28 days. No protection was observed in non-reperfused post-infarcted hearts. The respiratory control index of mitochondria was significantly reduced in reperfused infarcted hearts at 2-days with no effect at 28-days post-infarction on reperfused and non-reperfused hearts. Likewise, only a minor increase in reactive oxygen species production was observed at 2-days in non-reperfused post-infarcted hearts.

CONCLUSION

This study demonstrates that CyP-D inhibition exerts cardioprotective effects in reperfused but not in non-reperfused infarcted hearts of female rats, and the effects are observed only during acute post-infarction injury.

The protective effect of Er-Xian decoction against myocardial injury in menopausal rat model

Background

Er-Xian decoction (EXD), a formula of Chinese medicine, is often used to treat menopausal syndrome in China. The aim of the present study was to explore the potential cardioprotective mechanism of EXD against myocardial injury in an ovariectomy-induced menopausal rat model.

Methods

We divided the female Wistar rats into ovariectomy group and sham operation group (SHAM group). The ovariectomized (OVX) rats received treatment of vehicle (OVX group), EXD (EXD group) or 17β-estradiol (E2 group). After 12-week of treatment, the level of estradiol in serum was detected using an electrochemiluminescence immunoassay, and electrophysiologic changes in myocardial action potentials (AP) were evaluated using intracellular microelectrode technique. Changes in the histopathology of the left ventricle and the ultrastructure of the cardiomyocytes were observed by hematoxylin and eosin (HE) staining and transmission electronmicroscopy to assess myocardial injury. Microarrays were applied for the evaluation of gene expression profiles in ventricular muscle of the OVX and EXD rats. Further pathway analyses of the differential expression genes were carried out using the Kyoto Encyclopedia of Genes and Genomes (KEGG). And real-time quantitative RT-PCR (qRT-PCR) was used for verification of the key findings.

Results

The results from electrophysiological and histomorphological observations demonstrated that EXD had a substantial myocardial protective effect. The EXD-treated rats, in comparison with the OVX rats, demonstrated up-regulated expression of 28 genes yet down-regulated expression of 157 genes in the ventricular muscle. The qRT-PCR assay validated all selected differential expression genes. The KEGG pathway analysis showed that the down-regulated genes were relevant to cardiomyopathy and myocardial contractility. EXD could decrease the mRNA expressions of cardiac myosin (Myh7, Myl2) and integrin (Itgb5) in the ventricular myocardium.

Conclusion

EXD had a protective effect against myocardial injury in OVX rats, and this cardioprotective effect may be associated with modulation of the expression of cardiac myosin or integrin at the mRNA level.

Electronic supplementary material

The online version of this article (10.1186/s12906-018-2311-9) contains supplementary material, which is available to authorized users.

Serotonin transporter inhibition during neonatal period induces sex-dependent effects on mitochondrial bioenergetics in the rat brainstem

The serotonin reuptake is mainly regulated by the serotonin transporters (SERTs), which are abundantly found in the raphe nuclei, located in the brainstem. Previous studies have shown that dysfunction in the SERT has been associated with several disorders, including depression and cardiovascular diseases. In this manuscript, we aimed to investigate how gender and the treatment with a serotonin selective reuptake inhibitor (SSRI) could affect mitochondrial bioenergetics and oxidative stress in the brainstem of male and female rats. Fluoxetine, our chosen SSRI, was used during the neonatal period (i.e., from postnatal Day 1 to postnatal Day 21-PND1 to PND21) in both male and female animals. Thereafter, experiments were conducted in adult rats (60 days old). Our results demonstrate that, during lactation, fluoxetine treatment modulates the mitochondrial bioenergetics in a sex-dependent manner, such as improving male mitochondrial function and female antioxidant capacity.

Estrogen deprivation aggravates cardiometabolic dysfunction in obese-insulin resistant rats through the impairment of cardiac mitochondrial dynamics

The incidence of cardiovascular disease and metabolic syndrome increases after the onset of menopause, suggesting estrogen has a vital role in their prevention. Mitochondrial dynamics are known to play an important role in the maintenance of cardiac physiological function. However, the effects of estrogen deprivation on cardiometabolic status and cardiac mitochondrial dynamics under conditions of obese-insulin resistance have never been investigated. We hypothesized that estrogen deprivation aggravates cardiac dysfunction through increased cardiac mitochondrial fission in obese-insulin resistant rats. Female rats were fed on either a high fat (HFD, 57.60% fat) or normal (ND, 19.77% fat) diet for 13 weeks. The rats were then divided into 4 groups. Two sham groups (HFS and NDS) and 2 operated or ovariectomized (HFO and NDO) groups (n = 8/group). Six weeks after surgery, metabolic status, heart rate variability (HRV), left ventricular (LV) function, cardiac mitochondrial function and dynamics, and metabolic parameters were determined. Insulin resistance developed in NDO, HFS and HFO rats as indicated by increased plasma insulin and HOMA index. Although rats in both NDO and HFS groups had markedly impaired LV function indicated by reduced %LVFS and impaired cardiac mitochondrial function, rats in the HFO group had the most severe impairments. Moreover, the estrogen deprived rats (NDO and HFO) had increased cardiac mitochondrial fission through activation of phosphorylation of Drp-1 at serine 616. Our findings indicated that estrogen deprivation caused the worsening of LV dysfunction through increased cardiac mitochondrial fission in obese-insulin resistant rats.

Estrogenic regulation of skeletal muscle proteome: a study of premenopausal women and postmenopausal MZ cotwins discordant for hormonal therapy

Female middle age is characterized by a decline in skeletal muscle mass and performance, predisposing women to sarcopenia, functional limitations, and metabolic dysfunction as they age. Menopausal loss of ovarian function leading to low circulating level of 17β‐estradiol has been suggested as a contributing factor to aging‐related muscle deterioration. However, the underlying molecular mechanisms remain largely unknown and thus far androgens have been considered as a major anabolic hormone for skeletal muscle. We utilized muscle samples from 24 pre‐ and postmenopausal women to establish proteome‐wide profiles, associated with the difference in age (30–34 years old vs. 54–62 years old), menopausal status (premenopausal vs. postmenopausal), and use of hormone replacement therapy (HRT; user vs. nonuser). None of the premenopausal women used hormonal medication while the postmenopausal women were monozygotic (MZ) cotwin pairs of whom the other sister was current HRT user or the other had never used HRT. Label‐free proteomic analyses resulted in the quantification of 797 muscle proteins of which 145 proteins were for the first time associated with female aging using proteomics. Furthermore, we identified 17β‐estradiol as a potential upstream regulator of the observed differences in muscle energy pathways. These findings pinpoint the underlying molecular mechanisms of the metabolic dysfunction accruing upon menopause, thus having implications for understanding the complex functional interactions between female reproductive hormones and health.

The Role of Estrogen in Cardiac Metabolism and Diastolic Function

Heart failure with preserved ejection fraction (HFpEF) has similar prevalence and prognosis as HF with reduced EF, but there is no approved treatment for HFpEF. HFpEF is common in postmenopausal women, which suggests that the absence of estrogen (E2) plays a role in its pathophysiology. With the country's growing elderly population, the prevalence of HFpEF is rapidly increasing. This has triggered a renewed urgency in finding novel approaches to preventing and slowing the progression of HFpEF. In this review, we address the role of E2 in left ventricular diastolic function and how it impacts women with HFpEF as well as animal models. We also discuss the primary potential mechanisms that represent critical nodes in the mechanistic pathways of HFpEF and how new treatments could be developed to target those mechanisms.

Age and ischemia differentially impact mitochondrial ultrastructure and function in a novel model of age-associated estrogen deficiency in the female rat heart

Altered mitochondrial respiration, morphology, and quality control collectively contribute to mitochondrial dysfunction in the aged heart. Because myocardial infarction remains the leading cause of death in aged women, the present study utilized a novel rodent model to recapitulate human menopause to interrogate the combination of age and estrogen deficiency on mitochondrial ultrastructure and function with cardiac ischemia/reperfusion (I/R) injury. Female F344 rats were ovariectomized (OVX) at 15 months and studied at 24 months (MO OVX; n = 40) vs adult ovary intact (6 months; n = 41). Temporal declines in estrogen concomitant with increased visceral adipose tissue were observed in MO OVX vs adult. Following in vivo coronary artery ligation or sham surgery, state 3 mitochondrial respiration was selectively reduced by age in subsarcolemmal mitochondria (SSM) and by I/R in interfibrillar mitochondria (IFM); left ventricular maximum dP/dt was reduced in MO OVX (p < 0.05). Elevated cyclophilin D and exacerbated I/R-induced mitochondrial acetylation in MO OVX suggest permeability transition pore involvement and reduced protection vs adult (p < 0.05). Mitochondrial morphology by TEM revealed an altered time course of autophagy coordinate with attenuated Drp1 and LC3BII protein levels with age-associated estrogen loss (p < 0.05). Here, reductions in both SSM and IFM function may play an additive role in enhanced susceptibility to regional I/R injury in aged estrogen-deficient female hearts. Moreover, novel insight into altered cardiac mitochondrial quality control garnered here begins to unravel the potentially important regulatory role of mitochondrial dynamics on sustaining respiratory function in the aged female heart.

Estrogen regulates spatially distinct cardiac mitochondrial subpopulations

Increased susceptibility to permeability transition pore (mPTP) is a significant concern to decreased cardiac performance in postmenopausal females. The goal of this study was to assess the effects of estrogen deficiency on the two spatially distinct mitochondrial subpopulations from left ventricle: subsarcolemmal mitochondria (SSM) and intermyofibrillar mitochondria (IFM) based on: morphology, membrane potential, oxidative phosphorylation, mPTP and reactive oxygen species production. Female rats (8weeks old) that underwent bilateral ovariectomy were randomly assigned to receive daily treatment with placebo (OVX), estrogen replacement (OVX+E2) and Sham for 60days. The yield for IFM was found higher in the OVX group and lower in the SSM. SSM internal complexity and size were higher in the OVX group, although membrane potential was not different. The maximal rate of mitochondrial respiration, states 3 and 4, using glutamate+malate as substrate, were higher in IFM and SSM from the OVX group. The respiratory control ratio (RCR - state3/state 4), was not different in both SSM and IFM with glutamate+malate. The ADP:O ratio was found lower in IFM and SSM from OVX compared to Sham. When pyruvate was used, state 3 was found unchanged in both IFM and SSM, state 4 was greater in IFM from OVX rats compared to Sham and the ADP/O ratio was decreased. The RCR was unchanged in both subpopulations. The IFM from OVX rats presented a lower Ca²⁺retention capacity compared to Sham, however, the SSM remained unchanged. Hydrogen peroxide formation was found increased in the IFM from OVX animals with glutamate+malate and rotenone+succinate as substrates. The SSM showed increased ROS production only with rotenone+succinate. Western blot analyzes showed decreased levels of PGC-1α and NRF-1 in the OVX group. Estrogen replacement was able to restore most of the alterations induced by ovariectomy. In conclusion, our data shows that estrogen deficiency has distinct effects on the two spatially distinct mitochondrial subpopulations in oxidative phosphorylation, morphology, calcium retention capacity and ROS production.

Mitochondria: a central target for sex differences in pathologies

It is increasingly acknowledged that a sex and gender specificity affects the occurrence, development, and consequence of a plethora of pathologies. Mitochondria are considered as the powerhouse of the cell because they produce the majority of energy-rich phosphate bonds in the form of adenosine tri-phosphate (ATP) but they also participate in many other functions like steroid hormone synthesis, reactive oxygen species (ROS) production, ionic regulation, and cell death. Adequate cellular energy supply and survival depend on mitochondrial life cycle, a process involving mitochondrial biogenesis, dynamics, and quality control via mitophagy. It appears that mitochondria are the place of marked sexual dimorphism involving mainly oxidative capacities, calcium handling, and resistance to oxidative stress. In turn, sex hormones regulate mitochondrial function and biogenesis. Mutations in genes encoding mitochondrial proteins are the origin of serious mitochondrial genetic diseases. Mitochondrial dysfunction is also an important parameter for a large panel of pathologies including neuromuscular disorders, encephalopathies, cardiovascular diseases (CVDs), metabolic disorders, neuropathies, renal dysfunction etc. Many of these pathologies present sex/gender specificity. Here we review the sexual dimorphism of mitochondria from different tissues and how this dimorphism takes part in the sex specificity of important pathologies mainly CVDs and neurological disorders.

Mechanistic Pathways of Sex Differences in Cardiovascular Disease

Major differences between men and women exist in epidemiology, manifestation, pathophysiology, treatment, and outcome of cardiovascular diseases (CVD), such as coronary artery disease, pressure overload, hypertension, cardiomyopathy, and heart failure. Corresponding sex differences have been studied in a number of animal models, and mechanistic investigations have been undertaken to analyze the observed sex differences. We summarize the biological mechanisms of sex differences in CVD focusing on three main areas, i.e., genetic mechanisms, epigenetic mechanisms, as well as sex hormones and their receptors. We discuss relevant subtypes of sex hormone receptors, as well as genomic and nongenomic, activational and organizational effects of sex hormones. We describe the interaction of sex hormones with intracellular signaling relevant for cardiovascular cells and the cardiovascular system. Sex, sex hormones, and their receptors may affect a number of cellular processes by their synergistic action on multiple targets. We discuss in detail sex differences in organelle function and in biological processes. We conclude that there is a need for a more detailed understanding of sex differences and their underlying mechanisms, which holds the potential to design new drugs that target sex-specific cardiovascular mechanisms and affect phenotypes. The comparison of both sexes may lead to the identification of protective or maladaptive mechanisms in one sex that could serve as a novel therapeutic target in one sex or in both.

Estrogen Protects the Female Heart from Ischemia/Reperfusion Injury through Manganese Superoxide Dismutase Phosphorylation by Mitochondrial p38β at Threonine 79 and Serine 106

A collective body of evidence indicates that estrogen protects the heart from myocardial ischemia/reperfusion (I/R) injury, but the underlying mechanism remains incompletely understood. We have previously delineated a novel mechanism of how 17β-estradiol (E2) protects cultured neonatal rat cardiomyocytes from hypoxia/reoxygenation (H/R) by identifying a functionally active mitochondrial pool of p38β and E2-driven upregulation of manganese superoxide dismutase (MnSOD) activity via p38β, leading to the suppression of reactive oxygen species (ROS) and apoptosis. Here we investigate these cytoprotective actions of E2 in vivo. Left coronary artery ligation and reperfusion was used to produce I/R injury in ovariectomized (OVX) female mice and in estrogen receptor (ER) null female mice. E2 treatment in OVX mice reduced the left ventricular infarct size accompanied by increased activity of mitochondrial p38β and MnSOD. I/R-induced infarct size in ERα knockout (ERKO), ERβ knockout (BERKO) and ERα and β double knockout (DERKO) female mice was larger than that in wild type (WT) mice, with little difference among ERKO, BERKO, and DERKO. Loss of both ERα and ERβ led to reduced activity of mitochondrial p38β and MnSOD at baseline and after I/R. The physical interaction between mitochondrial p38β and MnSOD in the heart was detected by co-immunoprecipitation (co-IP). Threonine 79 (T79) and serine 106 (S106) of MnSOD were identified to be phosphorylated by p38β in kinase assays. Overexpression of WT MnSOD in cardiomyocytes reduced ROS generation during H/R, while point mutation of T79 and S106 of MnSOD to alanine abolished its antioxidative function. We conclude that the protective effects of E2 and ER against cardiac I/R injury involve the regulation of MnSOD via posttranslational modification of the dismutase by p38β.

Cardiomyocyte-specific deletion of the G protein-coupled estrogen receptor (GPER) leads to left ventricular dysfunction and adverse remodeling: A sex-specific gene profiling analysis

Activation of G protein-coupled estrogen receptor (GPER) by its agonist, G1, protects the heart from stressors such as pressure-overload, ischemia, a high-salt diet, estrogen loss, and aging, in various male and female animal models. Due to nonspecific effects of G1, the exact functions of cardiac GPER cannot be concluded from studies using systemic G1 administration. Moreover, global knockdown of GPER affects glucose homeostasis, blood pressure, and many other cardiovascular-related systems, thereby confounding interpretation of its direct cardiac actions. We generated a cardiomyocyte-specific GPER knockout (KO) mouse model to specifically investigate the functions of GPER in cardiomyocytes. Compared to wild type mice, cardiomyocyte-specific GPER KO mice exhibited adverse alterations in cardiac structure and impaired systolic and diastolic function, as measured by echocardiography. Gene deletion effects on left ventricular dimensions were more profound in male KO mice compared to female KO mice. Analysis of DNA microarray data from isolated cardiomyocytes of wild type and KO mice revealed sex-based differences in gene expression profiles affecting multiple transcriptional networks. Gene Set Enrichment Analysis (GSEA) revealed that mitochondrial genes are enriched in GPER KO females, whereas inflammatory response genes are enriched in GPER KO males, compared to their wild type counterparts of the same sex. The cardiomyocyte-specific GPER KO mouse model provides us with a powerful tool to study the functions of GPER in cardiomyocytes. The gene expression profiles of the GPER KO mice provide foundational information for further study of the mechanisms underlying sex-specific cardioprotection by GPER.

Sex differences in the regulation of spatially distinct cardiac mitochondrial subpopulations

Spatially distinct mitochondrial subpopulation may mediate myocardial pathology through permeability transition pore opening (MPTP). The goal of this study was to assess sex differences on the two spatially distinct mitochondrial subpopulations: subsarcolemmal mitochondria (SSM) and intermyofibrillar mitochondria (IFM) based on morphology, membrane potential, mitochondrial function, oxidative phosphorylation, and MPTP. Aged matched Wistar rats were used to study SSM and IFM. Mitochondrial size was larger in SSM than in IFM in both genders. However, SSM internal complexity, yield, and membrane potential were higher in male than in female. The maximal rate of mitochondrial respiration, states 3 and 4, using glutamate + malate as substrate, were higher in IFM and SSM in the male group compared to female. The respiratory control ratio (RCR-state3/state 4), was not different in both SSM and IFM with glutamate + malate. The ADP:O ratio was found higher in IFM and SSM from female compared to males. When pyruvate was used, state 3 was found unchanged in both IFM and SSM, state 4 was also greater in male IFM compared to female. The RCR increased in the SSM while IFM remained the same. State 4 was higher in male SSM while in the IFM remained the same. The IFM presented a higher Ca(2+) retention capacity compared with SSM, however, there was a greater sensitivity to Ca(2+)-induced MPTP in SSM and IFM in the male group compared to female. In conclusion, our data show that spatially distinct mitochondrial subpopulations have sex-based differences in oxidative phosphorylation, morphology, and calcium retention capacity.

Regular exercise modulates cardiac mast cell activation in ovariectomized rats

It is well accepted that regular exercise is a significant factor in the prevention of cardiac dysfunction; however, the cardioprotective mechanism is as yet not well defined. We have examined whether regular exercise can modulate the activity of cardiac mast cells (CMC) after deprivation of female sex hormones, as well as the density and percentage degranulation of mast cells, in ventricular tissue of ovariectomized (OVX) rats after an 11-week running program. A significant increase in CMC density with a greater percentage degranulation was induced after ovarian sex hormone deprivation. Increased CMC density was prevented by estrogen supplements, but not by regular training. To the contrary, increased CMC degranulation in the OVX rat heart was attenuated by exercise training, but not by estrogen supplement. These findings indicate a significant correlation between the degree of CMC degranulation and myocyte cross-section area. However, no change in the expression of inflammatory mediators, including chymase, interleukin-6, and interleukin-10, was detected. Taken together, these results clearly indicate one of the cardioprotective mechanisms of regular aerobic exercise is the modulation of CMC activation.

GPER mediates the effects of 17β-estradiol in cardiac mitochondrial biogenesis and function

Considering the sexual dimorphism described in cardiac mitochondrial function and oxidative stress, we aimed to investigate the role of 17β-estradiol (E2) in these sex differences and the contribution of E2 receptors to these effects. As a model of chronic deprivation of ovarian hormones, we used ovariectomized (OVX) rats, half of which were treated with E2. Ovariectomy decreased markers of cardiac mitochondrial biogenesis and function and also increased oxidative stress, whereas E2 counteracted these effects. In H9c2 cardiomyocytes we observed that G-protein coupled estrogen receptor (GPER) agonist mimicked the effects of E2 in enhancing mitochondrial function and biogenesis, whereas GPER inhibitor neutralized them. These data suggest that E2 enhances mitochondrial function and decreases oxidative stress in cardiac muscle, thus it could be responsible for the sexual dimorphism observed in mitochondrial biogenesis and function in this tissue. These effects seem to be mediated through GPER stimulation.