Testosterone suppresses ventricular remodeling and improves left ventricular function in rats following myocardial infarction

Natriuretic peptide testing strategies in heart failure: A 2023 update

Natriuretic peptides (NPs), including B-type natriuretic peptide (BNP) and N-terminal pro-BNP (NT-proBNP), have been recommended as standard biomarkers for diagnosing heart failure (HF), and one of the strongest risk predictors for mortality and HF hospitalization regardless of ejection fraction (EF) and etiology of HF. BNP is an active neurohormone opposing renin-angiotensin-aldosterone and sympathetic nervous system overactivated in HF, whereas NT-proBNP is an inactive prohormone released from cardiomyocytes in response to wall stress. Despite substantial advances in the development of guideline-directed medical therapy (GDMT) for HF with reduced EF, studies demonstrating direct benefits of NP-guided chronic HF therapy on mortality, HF hospitalization, and GDMT optimization have yielded conflicting results. However, accumulating evidence shows that achieving prespecified BNP or NT-proBNP target over time is significantly associated with favorable outcomes, suggesting that benefits of serially measured NPs may be limited to particular groups of HF patients, such as those with extreme levels of baseline BNP or NT-proBNP, which could represent severe phenotypes of HF associated with natriuretic peptide resistance or cardiorenal syndrome. Over the past decade, clinical utilization of BNP and NT-proBNP has been expanded, especially using serial NP measurements for guiding HF therapy, optimizing GDMT and identifying at-risk patients with HF phenotypes who may be minimally symptomatic or asymptomatic.

Testosterone, Hypogonadism, and Heart Failure

Male hypogonadism is defined as low circulating testosterone level associated with signs and symptoms of testosterone deficiency. Although the bidirectional link between hypogonadism and cardiovascular disease has been clarified, the association between testosterone and chronic heart failure (HF) is more controversial. Herein, we critically review published studies relating to testosterone, hypogonadism, and HF and provide practical clinical information on proper diagnosis and treatment of male hypogonadism in patients with HF. In general, published studies are extremely heterogeneous, frequently have not adhered to hypogonadism guidelines, and suffer from many intrinsic methodological inaccuracies; therefore, data provide only low-quality evidence. Nevertheless, by selecting the few methodologically robust studies, we show the prevalence of testosterone deficiency (30%-50%) and symptomatic hypogonadism (15%) in men with HF is significant. Low testosterone correlates with HF severity, New York Heart Association class, exercise functional capacity, and a worse clinical prognosis and mortality. Interventional studies on testosterone treatment in men with HF are inconclusive but do suggest beneficial effects on exercise capacity, New York Heart Association class, metabolic health, and cardiac prognosis. We suggest that clinicians should measure testosterone levels in men with HF who have symptoms of a testosterone deficiency and conditions that predispose to hypogonadism, such as obesity and diabetes. These patients-if diagnosed as hypogonadal-may benefit from the short- and long-term effects of testosterone replacement therapy, which include improvements in both cardiac prognosis and systemic outcomes. Further collaborative studies involving both cardiologists and endocrinologists are warranted.

Cardiovascular Properties of the Androgen-Induced PCOS Model in Rats: The Role of Oxidative Stress

Polycystic ovary syndrome (PCOS) is a multifaced reproductive endocrinopathy affecting 6-20% of women of childbearing age. It was previously shown that women with PCOS have an increased risk of cardiovascular (CV) diseases. The aim of this study was to evaluate the cardiodynamic parameters of isolated rats' hearts, blood pressure levels, and histomorphological changes in the heart tissue following the androgen-induced PCOS model in rats and the role of oxidative stress in the development of these CV properties of PCOS. 21-day-old female rats (n = 12) were divided into control and PCOS groups. PCOS was induced by administration of testosterone enanthate (1 mg/kg BW, daily) during 35 days. During the autoregulation protocol (40-120 mmHg) on the Langendorff apparatus, ex vivo cardiodynamic parameters of retrogradely perfused hearts showed enhanced contractile function and increased lusitropic effects in the left ventricle (LV) in PCOS rats. Systolic and diastolic pressures in LV were elevated at all perfusion pressure values. Systemic arterial systolic blood pressure showed borderline elevation, while mean arterial blood pressure was significantly higher in PCOS rats. Histological evaluation of heart tissue depicted hypertrophic (8.3%) alterations in LV cardiomyocytes and increase (7.3%) in LV wall thickness. Oxidative stress parameters were altered in systemic circulation, coronary venous effluent (CVE), and heart tissue. Levels of superoxide dismutase and reduced glutathione were decreased in blood and heart tissue, while catalase activity was not altered. Degree of lipid peroxidation was increased in circulation as well as heart tissue. Increased levels of O₂⁻ in CVE indicated the cardiotoxic effects in the rat PCOS model. The mentioned alterations of oxidative stress parameters in the blood, CVE, and heart could be recommended as potential contributors underlying the development of CV risk in PCOS women.

Testosterone therapy and cardiovascular diseases

Since it was first synthesised in 1935, testosterone (T) has been viewed as the mythical Fountain of Youth, promising rejuvenation, restoring sexual appetites, growing stronger muscles, and quicker thinking. T is endowed with direct effects on myocardial and vascular structure and function, as well as on risk factors for cardiovascular (CV) disease. Indeed, low serum T levels are a risk factor for diabetes, metabolic syndrome, inflammation, and dyslipidaemia. Moreover, many studies have shown that T deficiency per se is an independent risk factor of CV and all-cause mortality. On this background and due to direct-to-patient marketing by drug companies, we have witnessed to the widespread use of T replacement therapy (TT) without clear indications particularly in late-life onset hypogonadism. The current review will dwell upon current evidence and controversies surrounding the role of T in the pathophysiology of CV diseases, the link between circulating T levels and CV risk, and the use of replacing T as a possible adjuvant treatment in specific CV disorders. Specifically, recent findings suggest that heart failure and type 2 diabetes mellitus represent two potential targets of T therapy once that a state of hypogonadism is diagnosed. However, only if ongoing studies solve the CV safety issue the T orchid may eventually 'bloom'.

Testosterone, cardiomyopathies, and heart failure: a narrative review

Testosterone exerts an important regulation of cardiovascular function through genomic and nongenomic pathways. It produces several changes in cardiomyocytes, the main actor of cardiomyopathies, which are characterized by pathological remodeling, eventually leading to heart failure. Testosterone is involved in contractility, in the energy metabolism of myocardial cells, apoptosis, and the remodeling process. In myocarditis, testosterone directly promotes the type of inflammation that leads to fibrosis, and influences viremia with virus localization. At the same time, testosterone exerts cardioprotective effects that have been observed in different studies. There is increasing evidence that low endogenous levels of testosterone have a negative impact in some cardiomyopathies and a protective impact in others. This review focuses on the interrelationships between testosterone and cardiomyopathies and heart failure.

Androgen Therapy in Male Patients Suffering from Type 2 Diabetes: A Review of Benefits and Risks

BACKGROUND

The current estimated numbers of patients with Type 2 Diabetes (T2D) is believed to be close to 10% of the whole populations of many geographical regions, causing serious concerns over the resulting elevated morbidity and mortality as well as the impact on health care systems around the world. In addition to negatively affecting the quality of life, diabetes is associated with cardiovascular and cerebrovascular complications, indicating that appropriate drug therapy should not only deal with metabolic dysfunction but also protect the vascular system, kidney function and skeletal muscle mass from the effects of the epigenetic changes induced by hyperglycaemia.

OBJECTIVE

To provide an insight into the management of hypogonadism associated with T2D, this review focuses on clinical observations related to androgen therapy in qualified diabetic patients, and discusses the lines of evidence for its benefits and risks. The potential interactions of testosterone with medicines used by patients with T2D will also be discussed.

CONCLUSION

From recent clinical findings, it became evident that a considerable percentage of patients suffering from T2D manifested low serum testosterone and experienced diminished sexual activity, as well as reduced skeletal muscle mass and lower bone density. Although there are some controversies, Testosterone Replacement Therapy (TRT) for this particular population of patients appears to be beneficial overall only if it is implemented carefully and monitored regularly.

Response Gene to Complement 32 Maintains Blood Pressure Homeostasis by Regulating α-Adrenergic Receptor Expression

RATIONALE

Hypertension prevalence is much higher among children and adolescents with low birth weight and greater postnatal weight gain than in individuals with normal birth weight. However, the cause and molecular mechanisms underlying this complication remain largely unknown. Our previous studies have shown that RGC-32 (response gene to complement 32)-deficient (RGC-32^-/-) mice are born significantly smaller but grow faster than their WT (wild type) controls, which allows adult RGC-32^-/- mice to attain body weights similar to those of control mice.

OBJECTIVE

The objective of this study is to determine whether RGC-32^-/- mice develop hypertension, and if so, to elucidate the underlying mechanisms.

METHODS AND RESULTS

By using a radiotelemetry system, we found that RGC-32^-/- mice exhibit higher mean arterial pressure than WT mice (101±4 versus 119±5 mm Hg), which enabled us to use RGC-32^-/- mice to study the mechanisms underlying low birth weight-related hypertension. The increased blood pressure in RGC-32^-/- mice was associated with increased vascular tone and decreased distensibility of small resistance arteries. The increased vascular tone was because of an increase in the relative contribution of sympathetic versus parasympathetic activity and was linked to increased expression of AT1R (angiotensin II type I receptor) and α1-AdR (α1-adrenergic receptor) in arterial smooth muscles. Mechanistically, RGC-32 regulated AT1R gene transcription by interacting with Sp1 (specificity protein 1) transcription factor and further blocking its binding to the AT1R promoter, leading to suppression of AT1R expression. The attenuation of AT1R leads to reduction in α1-AdR expression, which was critical for the balance of sympathetic versus parasympathetic control of vascular tone. Of importance, downregulation of RGC-32 in arterial smooth muscles was also associated with low birth weight and hypertension in humans.

CONCLUSIONS

Our results indicate that RGC-32 is a novel protein factor vital for maintaining blood pressure homeostasis, especially in individuals with low birth weight.

Obestatin ameliorates water retention in chronic heart failure by downregulating renal aquaporin 2 through GPR39, V2R and PPARG signaling

AIMS

Obestatin regulates water metabolism by inhibiting arginine vasopressin (AVP) release and upregulated obestatin has been detected in patients with chronic heart failure (CHF). However, the significance of obestatin in CHF, particularly with regard to water retention and aquaporin 2 (AQP2) expression, remains unknown.

MAIN METHODS

Using a CHF rat model, the effects of 2-week exogenous obestatin administration were evaluated. Expression of AQP2 was evaluated by immunoblotting, immunohistochemical staining, and quantitative real-time PCR (qPCR) in CHF rat model and mouse inner medullary collecting duct (mIMCD) 3 cell line. Moreover, the influence of obestatin on the genetic transcription profile in mIMCD3 cells was evaluated by microarray, and the potential regulatory mechanisms of obestatin on AQP2 were evaluated by RNA silencing of vasopressin receptor 2 (V2R), peroxisome proliferator-activated receptor gamma (PPARG), and G protein-coupled receptor 39 (GPR39).

KEY FINDINGS

Obestatin increased urinary output and improved expression of CHF biomarker without significantly altering cardiac function, plasma electrolyte concentrations, or the plasma AVP concentration. AQP2 expression was significantly reduced. The results of microarray analyses and qPCR indicated that mRNA levels of Aqp2, Pparg, and V2r were significantly decreased. Inhibition of V2r and Pparg mRNA further reduced the expression of AQP2, while the inhibitory efficacy of obestatin on AQP2 was significantly offset after Gpr39 knockdown.

SIGNIFICANCE

Long-term treatment with obestatin improves water retention in CHF by increasing urinary output through downregulation of AQP2 expression in renal IMCD cells. These effects may be at least partially mediated by regulation of GPR39, V2R and PPARG signaling.

Obestatin Downregulating Aquaporin 2 Plasma Membrane Distribution Through a Short-Term Regulatory Effect

BACKGROUND

Previous studies have found that obestatin significantly inhibited water drinking and reduced the arginine vasopressin levels in the brain to decrease renal water reabsorption. However, obestatin is unable to cross the blood-brain barrier. Its effect on the body's kidney water metabolism in peripheral remains unknown.

MATERIALS AND METHODS

Expression and subcellular distribution of aquaporin 2 (AQP2) were detected by immunoblotting and immunofluorescence in mouse inner medullary collecting duct-3 (mIMCD-3) cells and congestive heart failure model rats. Moreover, expression of phosphorylated AQP2 (P-AQP2; Ser256) in mIMCD-3 cells was evaluated by immunoblotting.

RESULTS

After a 30-minute treatment with obestatin in mIMCD-3 cells and congestive heart failure model rats, the AQP2 plasma membrane distribution decreased, while AQP2 protein level, P-AQP2 (Ser256) protein level and phosphorylation ratio of AQP2 showed no significant change.

CONCLUSIONS

These findings suggest that obestatin has a short-term regulatory effect on the AQP2 plasma membrane distribution. In addition, obestatin decreases the APQ2 plasma membrane distribution probably by promoting the endocytosis of AQP2.

Cardiac myocyte proliferation and maturation near term is inhibited by early gestation maternal testosterone exposure

Polycystic ovary syndrome is a complex and common disorder in women, and those affected experience an increased burden of cardiovascular disease. It is an intergenerational syndrome, as affected women with high androgen levels during pregnancy "program" fetal development, leading to a similar phenotype in their female offspring. The effect of excess maternal testosterone exposure on fetal cardiomyocyte growth and maturation is unknown. Pregnant ewes received biweekly injections of vehicle (control) or 100 mg testosterone propionate between 30 and 59 days of gestation (early T) or between 60 and 90 days of gestation (late T). Fetuses were delivered at ~135 days of gestation, and their hearts were enzymatically dissociated to measure cardiomyocyte growth (dimensional measurements), maturation (proportion binucleate), and proliferation (nuclear Ki-67 protein). Early T depressed serum insulin-like growth factor 1 and caused intrauterine growth restriction (IUGR; P < 0.0005). Hearts were smaller with early T ( P < 0.001) due to reduced cardiac myocyte maturation ( P < 0.0005) and proliferation ( P = 0.017). Maturation was also lower in male than female fetuses ( P = 0.004) independent of treatment. Late T did not affect cardiac growth. Early excess maternal testosterone exposure depresses circulating insulin-like growth factor 1 near term and causes IUGR in both female and male offspring. These fetuses have small, immature hearts with reduced proliferation, which may reduce cardiac myocyte endowment and predispose to adverse cardiac growth in postnatal life. While excess maternal testosterone exposure leads to polycystic ovary syndrome and cardiovascular disease in female offspring, it may also predispose to complications of IUGR and cardiovascular disease in male offspring. NEW & NOTEWORTHY Using measurements of cardiac myocyte growth and maturation in an ovine model of polycystic ovary syndrome, this study demonstrates that early gestation excess maternal testosterone exposure reduces near-term cardiomyocyte proliferation and maturation in intrauterine growth-restricted female and male fetuses. The effect of testosterone is restricted to exposure during a specific period early in pregnancy, and the effects appear mediated through reduced insulin-like growth factor 1 signaling. Furthermore, male fetuses, regardless of treatment, had fewer mature cardiomyocytes than female fetuses.

17β-Estradiol treatment reversed left ventricular dysfunction in castrated male rats: an echocardiographic study

No data are available on heart function in chronic testosterone deficiency and on the effect of estrogen treatment. Eighteen 4-week-old male Lewis rats were randomly divided into 3 groups (n = 6): 1 group of sham-operated rats and 2 groups of castrated rats. Sixty-six weeks after surgery, 1 castrated group received a dose of 17β-estradiol (10 μg/kg per day) and the remaining 2 groups received a placebo subcutaneously for 14 days. Left ventricular (LV) systolic and diastolic functions were measured by transthoracic echocardiography. Castration decreased LV ejection fraction (9%) and fractional shortening (15%) and deteriorated LV diastolic function (94%). 17β-Estradiol treatment increased LV ejection fraction (15%) and fractional shortening (31%) and improved LV diastolic function (48%). Plasma testosterone concentrations were decreased in both castrated groups. In conclusion, chronic testosterone deficiency induced LV systolic and diastolic dysfunction; these disorders were reversed by short-term treatment with 17β-estradiol.

Sex hormone levels and change in left ventricular structure among men and post-menopausal women: The Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

Sex hormone (SH) levels may contribute to sex differences in the risk of heart failure with preserved ejection fraction (HFpEF). We examined the associations of SH levels with left ventricular mass (LVM) and mass (M):volume (V) ratio, which are risk markers for HFpEF.

STUDY DESIGN

We studied 1941 post-menopausal women and 2221 men, aged 45-84 years, participating in the Multi-Ethnic Study of Atherosclerosis (MESA). Serum SH levels, cardiac magnetic resonance imaging (MRI) and ejection fraction (EF) ≥50% had been recorded at baseline (2000-2002). Of these participants, 2810 underwent repeat MRI at Exam 5 (2010-2012). Stratified by sex, linear mixed-effect models were used to test associations between SH and sex hormone binding globulin (SHBG) level [per 1 SD greater log-transformed (SH)] with baseline and change in LV structure. Models were adjusted for age, race/ethnicity, center, height, weight, education, physical activity and smoking, and, in women, for hormone therapy and years since menopause.

MAIN OUTCOME MEASURES

LVM and M:V ratio.

RESULTS

After a median of 9.1 years, higher free testosterone levels were independently associated with a modest increase in LVM (g/yr) in women [0.05 (95% CI 0.01, 0.10)] and men [0.16 (0.03, 0.28)], while higher SHBG levels were associated with less LVM change (g/yr) in women [-0.07 (-0.13, -0.01)] and men [-0.15 (-0.27, -0.02)]. In men, higher dehydroepiandrosterone and estradiol levels were associated with increased LVM. Among women, free testosterone levels were positively and SHBG levels inversely associated with change in M:V ratio.

CONCLUSION

A more androgenic profile (higher free testosterone and lower SHBG levels) is associated with a greater increase in LVM in men and women and greater increase in M:V ratio in women over the course of 9 years.

Pathophysiology of Aortic Valve Stenosis: Is It Both Fibrocalcific and Sex Specific?

Our understanding of the fundamental biology and identification of efficacious therapeutic targets in aortic valve stenosis has lagged far behind the fields of atherosclerosis and heart failure. In this review, we highlight the most clinically relevant problems facing men and women with fibrocalcific aortic valve stenosis, discuss the fundamental biology underlying valve calcification and fibrosis, and identify key molecular points of intersection with sex hormone signaling.