Testosterone improves cardiac function and alters angiotensin II receptors in isoproterenol-induced heart failure

Grapevine Shoot Extract Rich in Trans-Resveratrol and Trans-ε-Viniferin: Evaluation of Their Potential Use for Cardiac Health

A grapevine shoot extract (GSE) was obtained using ultrasound-assisted extraction and characterized. The main phenolic constituents were identified as stilbenoids. Among them, trans-resveratrol and trans-ε-viniferin stood out. The GSE was administered to an isoproterenol-induced myocardial injury animal model. The extract alleviated the associated symptoms of the administration of the drug, i.e., the plasma lipid profile was improved, while the disturbed plasma ion concentration, the cardiac dysfunction markers, the DNA laddering, and the necrosis of myocardial tissue were diminished. This effect could be related to the anti-oxidative potential of GSE associated with its antioxidant properties, the increased levels of endogenous antioxidants (glutathione and enzymatic antioxidants), and the diminished lipid peroxidative markers in the heart. The results also revealed angiotensin-converting enzyme (ACE)-inhibitory activity, which indicated the potential of GSE to deal with cardiovascular disease events. This work suggests that not only trans-resveratrol has a protective role in heart function but also GSE containing this biomolecule and derivatives. Therefore, GSE has the potential to be utilized in the creation of innovative functional ingredients.

Myocardial angiogenesis induced by concurrent vitamin D supplementation and aerobic-resistance training is mediated by inhibiting miRNA-15a, and miRNA-146a and upregulating VEGF/PI3K/eNOS signaling pathway

This study aimed to investigate the effects of co-treatment of aerobic-resistance training (ART), vitamin D₃ (VD₃) on cardiovascular function considering the involvement of microRNA-15a and microRNA-146a, vascular endothelial growth factor (VEGF), phosphatidylinositol-3 kinase (PI3K), and endothelial nitric oxide synthase (eNOS) after myocardial infarction (MI) in rats. To induce MI, male Wistar rats subcutaneously received isoproterenol for 2 days, then MI was confirmed by echocardiography. MI rats were divided into six groups (n = 8/group). MI + VD₃, MI + sesame oil (Veh), MI + ART, MI + VD₃ + ART, and MI + Veh + ART, and received the related treatments for 8 weeks. Exercise tests, echocardiography, real-time quantitative polymerase chain reaction (qRT-PCR), western blotting, and histological staining were performed after the end of treatments. The highest ejection fraction (EF%), fractional shortening (FS%), exercise capacity (EC), and maximal load test (MLT) amounts were observed in the groups treated with VD₃, ART, and VD₃ + ART (P < 0.05). These were accompanied by a significantly increased angiogenesis post-MI. Furthermore, the levels of circulating microRNA-15a and microRNA-146a were significantly decreased in these groups compared to MI rats that were together with a significant upregulation of cardiac VEGF, PI3K, and eNOS expression. Overall, the best results were observed in the group treated with VD₃ + ART. Concurrent VD₃ supplementation and ART attenuated microRNA-15a and microRNA-146a and induced angiogenesis via VEGF/PI3K/eNOS axis. This data demonstrate that concurrent VD₃ supplementation and ART is a more efficient strategy than monotherapy to improve cardiac function post-MI.

In vivo evaluation and molecular docking studies of Schinus molle L. fruit extract protective effect against isoproterenol-induced infarction in rats

The aim of the current study was to assess the potential cardiopreventive effect of the methanolic extract of S. molle L. (MESM) on isoproterenol-induced infarction in rats. The biomolecules content was evaluated using HPLC-DAD-ESI-QTOF-MS/MS analysis. On the 29th and 30th days, two successive injections of isoproterenol (ISO) were given to Wistar rats to provoke myocardial infarction following pretreatment with either MESM (60 mg/kg b.w) or Pidogrel (Pid; 2 mg/kg b.w.). A total of sixteen phenolics were identified with masazino-flavanone as the most prevalent compound (1726.12 µg/g dm). Results showed that MESM offered cardioprevention by normalizing the ST segment and reducing the elevated cardiac risk parameters. The altered lipid biomarkers together with the plasma ionic levels were improved. Additionally, MESM inhibited the cardiac oxidative stress generated by ISO injection though enhancing antioxidant enzymes (GSH, CAT, SOD and GPX) which reduced lipid peroxidation and protein oxidation. MESM reduced myocardial apoptosis by significantly repressing mRNA expressions of Caspase-3 and Bax, with an upregulated Bcl-2 expression. Moreover, MESM reduced DNA fragmentation as well as the infarct size observed by TTC staining. In addition, MESM exhibited an antifibrotic effect by downregulating TGF-1β expression and reducing collagen deposition in myocardial tissue, as confirmed by Trichrom Masson analysis. The histopathological findings revealed less muscle separation and fewer inflammatory cells in the ISO + MESM-treated rats. Results of the docking simulation indicated that catechin in MESM was inhibitory mainly due to hydrogen bonding interactions with PDI, ACE and TGF-β1 proteins which could highlight the antithrombotic and antifibrotic capacity of MESM.

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'.

Female Patients With Sleep-Disordered Breathing Display More Frequently Heart Failure With Preserved Ejection Fraction

Objective: Sleep-disordered breathing (SDB) is a widespread disease that is often associated with heart failure (HF) with preserved ejection fraction (HFpEF). HFpEF is more frequent in women than in men, but detailed pathomechanisms remain unclear. We investigated HFpEF in women and men in a high-risk cohort with SDB monitoring.

Methods and Results: Three hundred twenty-seven patients (84.4% men) undergoing elective coronary artery bypass grafting were prospectively subjected to SDB monitoring, and an apnea–hypopnea index (AHI) ≥15/h defined SDB. HF was classified according to current guidelines. HFpEF was significantly more frequent in SDB patients compared to those without SDB (28 vs. 17%, P = 0.016). This distribution was driven by an increased frequency of HFpEF in female SDB patients (48% vs. only 25% in male, P = 0.022). In accordance, female patients with SDB exhibited significantly more impaired diastolic left ventricular filling compared to men (echocardiographic E/e′). In contrast to men, in women, minimum oxygen saturation (O_2min, measured by polygraphy, R² = 0.470, P < 0.001) and time of oxygen saturation <90% (R² = 0.165, P = 0.044) were significantly correlated with E/e′. Moreover, the correlation between O_2min and E/e′ was significantly different in women compared to men (P < 0.001). Intriguingly, this association remained independent of clinical covariates in women [age, body mass index, systolic contractile dysfunction, diabetes mellitus, and glomerular filtration rate (GFR), R² = 0.534, P = 0.042, multivariate regression analysis]. Since angiotensin II signaling has been mechanistically linked to HF, we measured protein expression of its cleavage enzyme ACE2 in human right atrial appendage biopsies (Western blot). Intriguingly, we found a significantly decreased ACE2 expression preferentially in women with SDB (2.66 ± 0.42 vs. 4.01 ± 2.47 in men with SDB, P = 0.005). In accordance, left ventricular mass index was significantly increased in women with SDB compared to women without SDB.

Conclusion: In patients with SDB, HFpEF and diastolic dysfunction were more frequent in women compared to men. In contrast to men, the severity of SDB was associated with the degree of diastolic dysfunction in women. These insights might help to find sex-specific therapies for patients with sleep-disordered breathing and heart failure.

Clinical Trial Registration: Unique identifier: NCT02877745, URL: http://www.clinicaltrials.gov.

Physiological testosterone attenuates profibrotic activities of rat cardiac fibroblasts through modulation of nitric oxide and calcium homeostasis

Testosterone deficiency is associated with poor prognosis among patients with chronic heart failure (HF). Physiological testosterone improves the exercise capacity of patients with HF. In this study, we evaluated whether treatment with physiological testosterone contributes to anti-fibrogenesis by modifying calcium homeostasis in cardiac fibroblasts and we studied the underlying mechanisms. Nitric oxide (NO) analyses, calcium (Ca²⁺) fluorescence, and Western blotting were performed in primary isolated rat cardiac fibroblasts with or without (control cells) testosterone (10, 100, 1,000 nmol/L) treatment for 48 hours. Physiological testosterone (10 nmol/L) increased NO production and phosphorylation at the inhibitory site of the inositol trisphosphate (IP3) receptor, thereby reducing Ca²⁺ entry, phosphorylated Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) expression, type I and type III pro-collagen production. Non-physiological testosterone-treated fibroblasts exhibited similar NO and collagen production capabilities as compared to control (testosterone deficient) fibroblasts. These effects were blocked by co-treatment with NO inhibitor (L-NG-nitro arginine methyl ester [L-NAME], 100 μmol/L). In the presence of the IP3 receptor inhibitor (2-aminoethyl diphenylborinate [2-APB], 50 μmol/L), testosterone-deficient and physiological testosterone-treated fibroblasts exhibited similar phosphorylated CaMKII expression. When treated with 2-APB or CaMKII inhibitor (KN93, 10 μmol/L), testosterone-deficient and physiological testosterone-treated fibroblasts exhibited similar type I, and type III collagen production. In conclusion, physiological testosterone activates NO production, and attenuates the IP3 receptor/Ca²⁺ entry/CaMKII signaling pathway, thereby inhibiting the collagen production capability of cardiac fibroblasts.

Renal sympathetic denervation attenuates left ventricle hypertrophy in spontaneously hypertensive rats by suppressing the Raf/MEK/ERK signaling pathway

OBJECTIVE

To explore the effect of renal sympathetic denervation (RSD) on left ventricle hypertrophy and the Raf/MEK/ERK signaling pathway in spontaneously hypertensive rats (SHRs).

METHODS

SHRs were divided into SHR, SHR + Sham, SHR + RSD and SHR + U0126 groups, with WKY rats as the baseline controls. The blood pressure of rats was observed, while myocardial fibrosis was evaluated through Masson staining. Thereafter, real-time quantitative polymerase chain reaction (qRT-PCR) was carried out to determine the levels of myocardial-hypertrophy-related markers, and Western blotting was used to measure the activity of the Raf/MEK/ERK signaling pathway.

RESULTS

In comparison with the WKY group, significant increases were observed in the systolic pressure and diastolic pressure of rats from the other four groups at different time points after surgery. In addition, rats in these groups had obvious increases in LVMI, renal NE and IVSd and decreases in LVEDd, LVEF and LVFS. In addition, the CVF of myocardial tissues was increased, with the upregulation of ANP, BNP and β-MHC and the downregulation of α-MHC. For the activity of the Raf/MEK/ERK signaling pathway, the levels of p-Raf/Raf, p-MEK/MEK and p-ERK1/2/ERK1/2 were all remarkably elevated (all P < .05). Further comparison with the SHR group showed that the above indexes in the rats were significantly improved in the RSD group and SHR + U0126 group (all P < .05).

CONCLUSION

RSD may decrease blood pressure, mitigate hypertension-induced left ventricle hypertrophy and improve cardiac function efficiently in SHRs via the suppression of the Raf/MEK/ERK signaling pathway.

Sex differences in cardiovascular actions of the renin-angiotensin system

Cardiovascular disease (CVD) remains a worldwide public health concern despite decades of research and the availability of numerous targeted therapies. While the intrinsic physiological mechanisms regulating cardiovascular function are similar between males and females, marked sex differences have been established in terms of CVD onset, pathophysiology, manifestation, susceptibility, prevalence, treatment responses and outcomes in animal models and clinical populations. Premenopausal females are generally protected from CVD in comparison to men of similar age, with females tending to develop cardiovascular complications later in life following menopause. Emerging evidence suggests this cardioprotection in females is, in part, attributed to sex differences in hormonal regulators, such as the renin-angiotensin system (RAS). To date, research has largely focused on canonical RAS pathways and shown that premenopausal females are protected from cardiovascular derangements produced by activation of angiotensin II pathways. More recently, a vasodilatory arm of the RAS has emerged that is characterized by angiotensin-(1-7) [(Ang-(1-7)], angiotensin-converting enzyme 2 and Mas receptors. Emerging studies provide evidence for a shift towards these cardioprotective Ang-(1-7) pathways in females, with effects modulated by interactions with estrogen. Despite well-established sex differences, female comparison studies on cardiovascular outcomes are lacking at both the preclinical and clinical levels. Furthermore, there are no specific guidelines in place for the treatment of cardiovascular disease in men versus women, including therapies targeting the RAS. This review summarizes current knowledge on sex differences in the cardiovascular actions of the RAS, focusing on interactions with gonadal hormones, emerging data for protective Ang-(1-7) pathways and potential clinical implications for established and novel therapies.

Late-onset hypogonadism: Reductio ad absurdum of the cardiovascular risk-benefit of testosterone replacement therapy

BACKGROUND

Low testosterone (T) level is considered a marker of poor cardiovascular health. Ten years ago, the Testosterone in Older Men with Mobility Limitations (TOM) trial was discontinued due to a higher number of adverse events in men receiving T compared with placebo. Since then, several studies have investigated the risks of T replacement therapy (TRT) in late-onset hypogonadism (LOH).

OBJECTIVE

To review the mechanism by which TRT could damage the cardiovascular system.

MATERIALS AND METHODS

Comprehensive literature search of recent clinical and experimental studies.

RESULTS

The mechanisms of T-mediated coronary vasodilation were reviewed with emphasis on calcium-activated and ATP-sensitive potassium ion channels. We showed how T regulates endothelial nitric oxide synthase (eNOS) and phosphoinositide 3-kinase/protein kinase B/eNOS signaling pathways in vessel walls and its direct effects on cardiomyocytes via β1-adrenergic and ryanodine receptors and provided data on myocardial infarction and heart failure. Vascular smooth muscle senescence could be explained by the modulation of growth factors, matrix metalloproteinase-2, and angiotensin II by T. Furthermore, leukocyte trafficking, facilitated by changes in TNF-α, could explain some of the effects of T on atheromatous plaques. Conflicting data on prothrombotic risk linked to platelet aggregation inhibition via NO-triggered arachidonate synthesis or increased aggregability due to enhanced thromboxane A in human platelets provide evidence regarding the hypotheses on plaque maturation and rupture risk. The effects of T on cardiac electrophysiology and oxygen delivery were also reviewed.

DISCUSSION

The effects of TRT on the cardiovascular system are complex. Although molecular studies suggest a potential benefit, several clinical observations reveal neutral or occasionally detrimental effects, mostly due to confounding factors.

CONCLUSIONS

Attempts to demonstrate that TRT damages the cardiovascular system via systematic analysis of the putative mechanisms led to the contradiction of the initial hypothesis. Current evidence indicates that TRT is safe once other comorbidities are addressed.

Lack of sexual dimorphism in a mouse model of isoproterenol-induced cardiac dysfunction

Sex-related differences in cardiovascular diseases are highly complex in humans and model-dependent in experimental laboratory animals. The objective of this work was to comprehensively investigate key sex differences in the response to acute and prolonged adrenergic stimulation in C57Bl/6NCrl mice. Cardiac function was assessed by trans-thoracic echocardiography before and after acute adrenergic stimulation (a single sub-cutaneous dose of isoproterenol 10 mg/kg) in 15 weeks old male and female C57Bl/6NCrl mice. Thereafter, prolonged adrenergic stimulation was achieved by sub-cutaneous injections of isoproterenol 10 mg/kg/day for 14 days in male and female mice. Cardiac function and morphometry were assessed by trans-thoracic echocardiography on the 15th day. Thereafter, the mice were euthanized, and the hearts were collected. Histopathological analysis of myocardial tissue was performed after staining with hematoxylin & eosin, Masson's trichrome and MAC-2 antibody. Gene expression of remodeling and fibrotic markers was assessed by real-time PCR. Cardiac function and morphometry were also measured before and after isoproterenol 10 mg/kg/day for 14 days in groups of gonadectomized male and female mice and sham-operated controls. In the current work, there were no statistically significant differences in the positive inotropic and chronotropic effects of isoproterenol between male and female C57Bl/6NCrl. After prolonged adrenergic stimulation, there was similar degree of cardiac dysfunction, cardiac hypertrophy, and myocardial fibrosis in male and female mice. Similarly, prolonged isoproterenol administration induced hypertrophic and fibrotic genes in hearts of male and female mice to the same extent. Intriguingly, gonadectomy of male and female mice did not have a significant impact on isoproterenol-induced cardiac dysfunction as compared to sham-operated animals. The current work demonstrated lack of significant sex-related differences in isoproterenol-induced cardiac hypertrophy, dysfunction, and fibrosis in C57Bl/6NCrl mice. This study suggests that female sex may not be sufficient to protect the heart in this model of isoproterenol-induced cardiac dysfunction and underscores the notion that sexual dimorphism in cardiovascular diseases is highly model-dependent.

Androgen-deprivation therapy impairs left ventricle functions in prostate cancer patients

BACKGROUND

Androgen-deprivation therapy (ADT) is a treatment option for locally advanced and metastatic prostate cancer (PCA). The aim of the study was to evaluate the effect of ADT on left ventricular (LV) functions assessed by speckle-tracking echocardiography (STE) in prostate cancer (PCA) patients.

METHODS

Forty-nine consecutive PCA patients (mean age 71.5 ± 6.7 years) who would be treated with radiotherapy and ADT and 32 consecutive PCA patients (mean age 71.9 ± 7.0 years) who would be treated with radical or partial prostatectomy and 42 age-matched healthy men (mean age 70.5 ± 9.1 years) were included in our study. The left ventricular functions were assessed by both conventional echocardiography and STE at baseline and 6 months later.

RESULTS

There were not any significant difference in characteristics of the patients and controls. There were not any significant differences in conventional echocardiographic measures at baseline and at 6th month among the PCA patients and controls. Although there were not any significant differences in STE measures at baseline among the PCA patients and controls, the strain measures of the PCA patients receiving ADT decreased significantly at the 6th month and were significantly lower compared to strain measures of PCA patients undergoing prostatectomy and controls. There was not any statistically significant difference in baseline and 6th-month strain measures of the PCA patients undergoing prostatectomy.

CONCLUSIONS

ADT might be associated with decrease in LV longitudinal, circumferential, and radial strain measures in patients with PCA. STE might be useful for early identification of LV subclinical impairment in PCA patients treated with ADT.

Testosterone plays a permissive role in angiotensin II-induced hypertension and cardiac hypertrophy in male rats

Sex hormones contribute to sex differences in blood pressure. Inappropriate activation of the renin-angiotensin system is involved in vascular dysfunction and hypertension. This study evaluated the role of androgens (testosterone) in angiotensin II (Ang II)-induced increase in blood pressure, vascular reactivity, and cardiac hypertrophy. Eight-week-old male Wistar rats underwent sham operation, castration, or castration with testosterone replacement. After 12 weeks of chronic changes in androgen status, Ang II (120 ng/kg per minute) or saline was infused for 28 days via subcutaneous miniosmotic pump, and changes in blood pressure was measured. Vascular reactivity and Ang II receptor levels were examined in mesenteric arteries. Heart weight, cardiac ANP mRNA levels, and fibrosis were also assessed. Ang II infusion increased arterial pressure in intact males. The Ang II-induced increase in hypertensive response was prevented in castrated males. Testosterone replacement in castrated males restored Ang II-induced hypertensive responses. Castration reduced vascular AT1R/AT2R ratio, an effect that was reversed by testosterone replacement. Ang II-induced hypertension was associated with increased contractile response of mesenteric arteries to Ang II and phenylephrine in intact and testosterone-replaced castrated males; these increases were prevented in castrated males. Ang II infusion induced increased left ventricle-to-body weight ratio and ANP mRNA expression, indicators of left ventricular hypertrophy, and fibrosis in intact and testosterone-replaced castrated males, and castration prevented the increase in these parameters caused by Ang II. This study demonstrates that testosterone plays a permissive role in development and maintenance of Ang II-induced vascular dysfunction, hypertension, and cardiac hypertrophy.

Histomorphological changes in the common carotid artery of the male rat in induced hypogonadism

The role of androgens in the development of cardiovascular diseases remains controversial. The current study therefore sought to determine the changes in the histomorphology of the common carotid artery of the male rat in orchidectomy-induced hypogonadism. Twenty-two Rattus norvegicus male rats aged 2 months were used. The rats were randomly assigned into baseline (n=4), experimental (n=9), and control (n=9) groups. Hypogonadism was surgically induced in the experimental group by bilateral orchiectomy under local anesthesia. At experiment weeks 3, 6, and 9, three rats from each group (experimental and control) were euthanized, their common carotid artery harvested, and routine processing was done for paraffin embedding, sectioning, and staining. The photomicrographs were taken using a digital photomicroscope for morphometric analysis. Orchidectomy resulted in the development of vascular fibrosis, with a significant increase in collagen fiber density and decrease in smooth muscle and elastic fiber density. Moreover, there was development of intimal hyperplasia, with fragmentation of medial elastic lamellae in the common carotid artery of the castrated rats. Orchidectomy induces adverse changes in structure of the common carotid artery of the male rat. These changes may impair vascular function, therefore constituting a possible structural basis for the higher incidences of cardiovascular diseases observed in hypogonadism.

Dietary normalization from a fat, fructose and cholesterol-rich diet to chow limits the amount of myocardial collagen in a Göttingen Minipig model of obesity

Background

Dietary interventions have been shown to attenuate some of the myocardial pathological alterations associated with obesity. This study evaluated the effect of dietary normalization from a fat/fructose/cholesterol-rich diet to chow on left ventricular (LV) myocardial fibrosis, fat infiltration and hypertrophy but also the specific influence of obesity, plasma lipids and glucose metabolism markers on heart morphology in a Göttingen Minipig model of obesity.

Methods

Forty castrated male Göttingen Minipigs were assigned to three groups fed either standard minipig chow (SD, n = 8) for 13 months, fat/fructose/cholesterol-rich diet (FFC, n = 16) for 13 months or fat/fructose/cholesterol-rich diet for 7 months and then changed to standard minipig chow for the remaining 6 months (FFC/SD, n = 16). Body weight, body fat percentage, plasma lipids and glucose metabolism markers were evaluated in all three groups after 6–7 months (prior to diet adjustment for FFC/SD) and again before termination. Further, biochemical quantification of myocardial collagen and triglyceride content, semi-quantitative histological evaluation of fibrosis and fat infiltration and quantitative histological analysis of collagen and cardiomyocyte diameter were performed and heart weight was obtained after termination. Group differences were evaluated using Kruskal-Wallis test and Fisher’s exact test for categorical variables. Pearson correlation analysis was performed to test for correlations between myocardial changes and selected explanatory variables. For non-parametric response variables, a Spearman correlation analysis was applied.

Results

Myocardial collagen content quantified biochemically was significantly lower in FFC/SD compared to FFC (P = 0.02). Furthermore, dietary normalization from a fat/fructose/cholesterol-rich diet to chow caused stagnation of body weight and body fat percentage, normalized intravenous glucose tolerance index (K_G) and plasma lipid levels.

Conclusion

Dietary normalization led to lower LV collagen content in obese Göttingen Minipigs. Despite gross obesity and significant deteriorations in glucose and lipid metabolism, only mild myocardial changes were found in this model of obesity and therefore further model optimization is warranted in order to induce more severe myocardial changes before dietary or pharmacological interventions.

Functional and structural changes in internal pudendal arteries underlie erectile dysfunction induced by androgen deprivation

Androgen deficiency is strongly associated with erectile dysfunction (ED). Inadequate penile arterial blood flow is one of the major causes of ED. The blood flow to the corpus cavernosum is mainly derived from the internal pudendal arteries (IPAs); however, no study has evaluated the effects of androgen deprivation on IPA's function. We hypothesized that castration impairs IPAs reactivity and structure, contributing to ED. In our study, Wistar male rats, 8-week-old, were castrated and studied 30 days after orchiectomy. Functional and structural properties of rat IPAs were determined using wire and pressure myograph systems, respectively. Protein expression was determined by Western blot and immunohistochemistry. Plasma testosterone levels were determined using the IMMULITE 1000 Immunoassay System. Castrated rats exhibited impaired erectile function, represented by decreased intracavernosal pressure/mean arterial pressure ratio. IPAs from castrated rats exhibited decreased phenylephrine- and electrical field stimulation (EFS)-induced contraction and decreased acetylcholine- and EFS-induced vasodilatation. IPAs from castrated rats exhibited decreased internal diameter, external diameter, thickness of the arterial wall, and cross-sectional area. Castration decreased nNOS and α-actin expression and increased collagen expression, p38 (Thr180/Tyr182) phosphorylation, as well as caspase 3 cleavage. In conclusion, androgen deficiency is associated with impairment of IPA reactivity and structure and increased apoptosis signaling markers. Our findings suggest that androgen deficiency-induced vascular dysfunction is an event involving hypotrophic vascular remodeling of IPAs.

Testosterone Deprivation Aggravates Left-Ventricular Dysfunction in Male Obese Insulin-Resistant Rats via Impairing Cardiac Mitochondrial Function and Dynamics Proteins

BACKGROUND

We have previously reported that testosterone deprivation at a very young age accelerated, but did not aggravate, left-ventricular (LV) dysfunction in obese insulin-resistant rats. However, the effects of testosterone deprivation during adulthood on LV function in obese insulin-resistant rats remains unclear. We hypothesized that testosterone deprivation aggravates LV dysfunction and cardiac autonomic imbalance via the impairment of cardiac mitochondrial function and dynamics proteins, a reduction in insulin receptor function, and an increase in apoptosis in obese insulin-resistant rats.

METHODS

Male rats were fed on either a normal diet (ND) or a high-fat diet (HFD) for 12 weeks. They were then subdivided into 2 groups: sham operation (NDS, HFS) and orchiectomy (NDO, HFO). Metabolic parameters, blood pressure, heart rate variability (HRV), and LV function were determined at baseline and before and after orchiectomy. Mitochondrial function and dynamics proteins, insulin signaling, and apoptosis were determined 12 weeks postoperatively.

RESULTS

HFS rats exhibited obese insulin resistance, depressed HRV, and LV dysfunction. In HFO rats, systolic blood pressure was increased with more excessive depression of HRV and increased LV dysfunction, compared with HFS rats. These adverse cardiac effects were consistent with markedly increased mitochondrial dysfunction, reduced mitochondrial complex I and III proteins, reduced mitochondrial fusion proteins, and increased apoptosis, compared with HFS rats. However, testosterone deprivation did not lead to any alteration in the insulin-resistant condition in HFO rats, compared with HFS rats.

CONCLUSION

We concluded that testosterone deprivation during adulthood aggravated the impairment of mitochondrial function, mitochondrial respiratory complex, mitochondrial dynamics proteins, and apoptosis, leading to LV dysfunction in obese insulin-resistant rats.

Ca2+/Calmodulin-Dependent Protein Kinase II and Androgen Signaling Pathways Modulate MEF2 Activity in Testosterone-Induced Cardiac Myocyte Hypertrophy

Testosterone is known to induce cardiac hypertrophy through androgen receptor (AR)-dependent and -independent pathways, but the molecular underpinnings of the androgen action remain poorly understood. Previous work has shown that Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) and myocyte-enhancer factor 2 (MEF2) play key roles in promoting cardiac myocyte growth. In order to gain mechanistic insights into the action of androgens on the heart, we investigated how testosterone affects CaMKII and MEF2 in cardiac myocyte hypertrophy by performing studies on cultured rat cardiac myocytes and hearts obtained from adult male orchiectomized (ORX) rats. In cardiac myocytes, MEF2 activity was monitored using a luciferase reporter plasmid, and the effects of CaMKII and AR signaling pathways on MEF2C were examined by using siRNAs and pharmacological inhibitors targeting these two pathways. In the in vivo studies, ORX rats were randomly assigned to groups that were administered vehicle or testosterone (125 mg⋅kg^-1⋅week^-1) for 5 weeks, and plasma testosterone concentrations were determined using ELISA. Cardiac hypertrophy was evaluated by measuring well-characterized hypertrophy markers. Moreover, western blotting was used to assess CaMKII and phospholamban (PLN) phosphorylation, and MEF2C and AR protein levels in extracts of left-ventricle tissue from control and testosterone-treated ORX rats. Whereas testosterone treatment increased the phosphorylation levels of CaMKII (Thr286) and phospholambam (PLN) (Thr17) in cardiac myocytes in a time- and concentration-dependent manner, testosterone-induced MEF2 activity and cardiac myocyte hypertrophy were prevented upon inhibition of CaMKII, MEF2C, and AR signaling pathways. Notably, in the hypertrophied hearts obtained from testosterone-administered ORX rats, both CaMKII and PLN phosphorylation levels and AR and MEF2 protein levels were increased. Thus, this study presents the first evidence indicating that testosterone activates MEF2 through CaMKII and AR signaling. Our findings suggest that an orchestrated mechanism of action involving signal transduction and transcription pathways underlies testosterone-induced cardiac myocyte hypertrophy.

Advanced Interfere Treatment of Diabetic Cardiomyopathy Rats by aFGF-Loaded Heparin-Modified Microbubbles and UTMD Technique

This study aims to investigate the preclinical performance and mechanism of a novel strategy of aFGF-loaded heparin-modified microbubbles (aFGF-HMB) combined with ultrasound-targeted microbubble destruction (UTMD) technique for diabetic cardiomyopathy (DCM) prevention. Type 1 diabetic rats were induced by streptozotocin. Twelve weeks after intervention, indexes from transthoracic echocardiography and cardiac catheterization showed that the left ventricular function in the aFGF-HMB/UTMD group was significantly improved compared with diabetes control (DM). From Picrosirius Red staining and TUNEL staining, the aFGF-HMB/UTMD group showed significant difference from the other groups. The cardiac collagen volume fraction (CVF) and myocardial cell apoptosis index (AI) in aFGF-HMB/UTMD group decreased to 7.2 % and 7.11 % respectively, compared with the DM group (CVF = 24.5 % and AI =20.3 % respectively). The results of myocardial microvascular density (MCD) also proved the strongest inhibition of aFGF-HMB/UTMD group on DCM progress. CD31 staining of aFGF-HMB/UTMD group reached 22 n/hrp, much higher than that of DM group (9 n/hrp). These results confirmed that the abnormalities including left ventricular dysfunction, myocardial fibrosis, cardiomyocytes apoptosis and microvascular rarefaction could be suppressed by twice weekly aFGF treatments for 12 consecutive weeks (free aFGF or aFGF-HMB+/-UTMD), with the strongest improvements observed in the aFGF-HMB/UTMD group (P < 0.05 vs free aFGF or aFGF-HMB). Western blot analyses of heart tissue further revealed the highest aFGF, anti-apoptosis protein (Bcl-2), VEGF-C, pAkt, pFoxo-3a levels and strongest reduction in pro-apoptosis proteins (Bax) level in aFGF-HMB/UTMD group. Overall, aFGF-HMB combined with UTMD technique might be developed as an effective strategy to prevent DCM in future clinical therapy.

Sex steroids in relation to cardiac structure and function in men

The prevalence of testosterone substitution as well as of androgen deprivation therapy in men is increasing. This review aims to summarise available knowledge of the effects of sex steroids on cardiac structure and function in men. MEDLINE was searched through PubMed. Original studies, systematic reviews and meta-analyses, and relevant citations were screened. A short-term hormonal intervention study in healthy young men with respect to echocardiographic parameters of structure and function was performed. Preclinical research provides sufficient evidence for the heart as a substrate for sex hormones. In animals, administration of oestradiol appears to have beneficial effects on cardiac structure and function, whereas administration of testosterone to noncastrated animals adversely affects cardiac function. However, the effects of sex steroids on cardiac function and structure appear more heterogeneous in human observational studies while comparative, prospective studies in humans are lacking. It is concluded that although effects of testosterone substitution as well as of androgen deprivation on cardiac structure and function can be expected based on pre-clinical research, there exists an important knowledge gap of the effects of hormonal intervention in men. As such, there is a need to address this question in future prospective intervention trials.

Androgen receptor (AR) in cardiovascular diseases

Cardiovascular diseases (CVDs) are still the highest leading cause of death worldwide. Several risk factors have been linked to CVDs, including smoking, diabetes, hyperlipidemia, and gender among others. Sex hormones, especially the androgen and its receptor, androgen receptor (AR), have been linked to many diseases with a clear gender difference. Here, we summarize the effects of androgen/AR on CVDs, including hypertension, stroke, atherosclerosis, abdominal aortic aneurysm (AAA), myocardial hypertrophy, and heart failure, as well as the metabolic syndrome/diabetes and their impacts on CVDs. Androgen/AR signaling exacerbates hypertension, and anti-androgens may suppress hypertension. Androgen/AR signaling plays dual roles in strokes, depending on different kinds of factors; however, generally males have a higher incidence of strokes than females. Androgen and AR differentially modulate atherosclerosis. Androgen deficiency causes elevated lipid accumulation to enhance atherosclerosis; however, targeting AR in selective cells without altering serum androgen levels would suppress atherosclerosis progression. Androgen/AR signaling is crucial in AAA development and progression, and targeting androgen/AR profoundly restricts AAA progression. Men have increased cardiac hypertrophy compared with age-matched women that may be due to androgens. Finally, androgen/AR plays important roles in contributing to obesity and insulin/leptin resistance to increase the metabolic syndrome.

Argirein alleviates stress-induced and diabetic hypogonadism in rats via normalizing testis endothelin receptor A and connexin 43

AIM

Argirein (rhein-arginine) is a derivative of rhein isolated from Chinese rhubarb (Rheum Officinale Baill.) that exhibits antioxidant and anti-inflammatory activities. In the present study we investigated the effects of argirein on stress-induced (hypergonadotrophic) and diabetic (hypogonadotrophic) hypogonadism in male rats.

METHODS

Stress-induced and diabetic hypogonadism was induced in male rats via injection of isoproterenol (ISO) or streptozotocin (STZ). ISO-injected rats were treated with argirein (30 mg·kg(-1)·d(-1), po) or testosterone replacement (0.5 mg·kg(-1)·d(-1), sc) for 5 days, and STZ-injected rats were treated with argirein (40-120 mg·kg(-1)·d(-1), po) or aminoguanidine (100 mg·kg(-1)·d(-1), po) for 4 weeks. After the rats were euthanized, blood samples and testes were collected. Serum hormone levels were measured, and the expression of endothelin receptor A (ETA), connexin 43 (Cx43) and other proteins in testes was detected. For in vitro experiments, testis homogenate was prepared from normal male rats, and incubated with ISO (1 μmol/L) or high glucose (27 mmol/L).

RESULTS

ISO injection induced hyper-gonadotrophic hypogonadism characterized by low testosterone and high FSH and LH levels in the serum, whereas STZ injection induced hypogonadotrophic hypogonadism as evidenced by low testosterone and low FSH and LH levels in the serum. In the testes of ISO- and STZ-injected rats, the expression of ETA, MMP-9, NADPH oxidase and pPKCε was significantly increased, and the expression of Cx43 was decreased. Administration of argirein attenuated both the abnormal serum hormone levels and the testis changes in ISO- and STZ-injected rats, and aminoguanidine produced similar actions in STZ-injected rats; testosterone replacement reversed the abnormal serum hormone levels, but did not affect the testis changes in ISO-injected rats. Argirein (0.3-3 μmol/L) exerted similar effects in testis homogenate incubated with ISO or high glucose in vitro.

CONCLUSION

Two types of hypogonadism of male rats exhibit increased expression of ETA and depressed expression of Cx43 in testes, despite different patterns of serum FSH and LH. Argirein alleviates the two types of male hypogonadism via normalizing ETA and Cx43 in testes.

Relationship between male hormonal status, Bezold–Jarisch reflex function, and ACE activity (cardiac and plasmatic)

The negative relationship between androgens and the Bezold–Jarisch reflex (BJR) has been demonstrated, but no studies evaluated the physiological influence of testosterone on this reflex. We evaluated the influence of male rat castration on the BJR, cardiac morphometric parameters, and the plasmatic and the cardiac angiotensin converting enzyme (ACE) activity. After castration (CAS), the rats were divided into 24 and 72 h (CAS24H, CAS72H), and 7 and 21 days (CAS7D, CAS21D) groups. The BJR was studied by administering increasing doses of phenylbiguanide (PBG; 1.5–24 μg/kg) at different times after castration. Castration results in the following: (i) reduction in testosterone levels (SHAM: 238.7 ± 15.1; CAS24H: 9.0 ± 0.5; CAS72H: 6.7 ± 0.4; CAS7D: 5.2 ± 0.2; and CAS21D: 2.2 ± 0.3 ng/dL; p < 0.05); (ii) no changes in 17β-estradiol; (iii) a reduced BJR sensitivity (PBG 6 μg/kg; SHAM: 77 ± 7; CAS24H: 63 ± 10; CAS72H: 55 ± 6; CAS7D: 54 ± 4; and CAS21D: 35 ± 2%; p < 0.01); (iv) a decrease in cardiac (SHAM: 107 ± 6; CAS24H: 92 ± 2; CAS72H: 82 ± 3; CAS7D: 54 ± 3; and CAS21D: 43 ± 4%; p < 0.05) and plasmatic (SHAM: 135 ± 8; CAS24H: 102 ± 5; CAS72H: 99 ± 3; CAS7D: 89 ± 4; and CAS21D: 56 ± 6%; p < 0.05) ACE activity. No changes were observed in cardiac morphometry and hemodynamic parameters. Therefore, castration leads to decrease in testosterone levels as early as 24 h, reduction in ACE activity and loss of BJR sensitivity 7 days after castration. The loss of BJR sensitivity was not related to cardiac morphometric changes and cardiovascular hemodynamics.

Sex hormones in the cardiovascular system

Gender-associated differences in the development of cardiovascular diseases have been described in humans and animals. These differences could explain the low incidence of cardiovascular disease in women in the reproductive period, such as stroke, hypertension, and atherosclerosis. The cardiovascular protection observed in females has been attributed to the beneficial effects of estrogen on endothelial function. Besides estrogen, sex hormones are able to modulate blood pressure by acting on important systems as cardiovascular, renal, and neural. They can have complementary or antagonistic actions. For example, testosterone can raise blood pressure by stimulating the renin-angiotensin-aldosterone system, whereas estrogen alone or combined with progesterone has been associated with decreased blood pressure. The effects of testosterone in the development of cardiovascular disease are contradictory. Although some researchers suggest a positive effect, others indicate negative actions of testosterone. Estrogens physiologically stimulate the release of endothelium-derived vasodilator factors and inhibit the renin-angiotensin system. Although the cardioprotective effects of estrogen are widely appreciated, little is known about the effects of progesterone, which is commonly used in hormone replacement therapy. Progesterone has both vasodilatory and vasoconstrictive effects in the vasculature, depending on the location of the vessel and the level of exposure. Nevertheless, the mechanisms through which sex hormones modulate blood pressure have not been fully elucidated. Therefore, the characterization of those could lead to a better understanding of hypertension in women and men and perhaps to improved forms of therapy.

Testosterone induces apoptosis in cardiomyocytes by increasing proapoptotic signaling involving tumor necrosis factor-α and renin angiotensin system

Anabolic androgenic steroids lead to cardiac complications and have been shown to exhibit proapoptotic effects in cardiac cells; however, the mechanism involved in those effects is unclear. The aim of this study was to assess whether apoptosis and the activation of caspase-3 (Casp-3) induced by testosterone in high concentrations involves increments in tumor necrosis factor-α (TNF-α) concentrations and angiotensin-converting enzyme (ACE) activity in cardiomyocytes (H9c2) cell cultures. Cardiomyocytes were treated with testosterone (5 × 10−6 mol/L), doxorubicin (9.2 × 10−6 mol/L), testosterone + etanercept (Eta; 6.67 × 10−5 mol/L), testosterone + losartan (Los; 10−7 mol/L), and testosterone + AC-DEVD-CHO (10−5 mol/L; Casp-3 inhibitor). Apoptosis was determined by flow cytometry and by the proteolytic activity of Casp-3. We demonstrated that incubation of H9c2 cells for 48 h with testosterone causes the apoptotic death of 60–70% of the cells and co-treatments with Eta, Los, or AC-DEVD-CHO reduced this effect. Testosterone also induces apoptosis (concentration dependent) and increases the proteolytic activity of Casp-3, which were reduced by co-treatments. TNF-α and ACE activities were elevated by testosterone treatment, while co-treatment with Los and Eta reduced these effects. We concluded that an interaction between testosterone, angiotensin II, and TNF-α induced apoptosis and Casp-3 activity in cultured cardiomyocytes, which contributed to the reduced viability of these cells induced by testosterone in toxic concentrations.

Impact of castration on changes in left ventricular diastolic pressure-volume relations induced by chronic adrenergic stimulation in rats

A reduced testosterone concentration characterizes heart failure and independently predicts outcomes. Although testosterone replacement therapy may have non cardiac-related therapeutic benefits in heart failure, whether reduced testosterone concentrations protect against adverse left ventricular remodeling (LV dilatation) is uncertain. We therefore evaluated whether surgical castration modifies LV dilatation after 6 months of daily injections of the β-adrenergic receptor (AR) agonist, isoproterenol (ISO) (0.015 mg·kg(-1)·d(-1)), to rats. The extent of LV dilatation and LV systolic chamber dysfunction were determined using both echocardiography and isolated perfused heart procedures. The extent of LV dilatation was determined from LV diastolic pressure-volume (P-V) relationships. As compared with the saline vehicle-treated group, after 6 months of β-AR activation in sham-castrated rats, a marked right shift in the LV diastolic P-V relationship was noted with an increased LV volume intercept at 0 mm Hg diastolic pressure (LV V(0) in milliliters) (ISO = 0.38 ± 0.02, saline vehicle = 0.30 ± 0.02, P < 0.05). However, chronic β-AR activation did not alter LV systolic chamber function either in vivo (LV endocardial fractional shortening, echocardiography) or ex vivo (LV end systolic elastance). Although castration decreased body weight, castration failed to modify the impact of ISO on the LV diastolic P-V relationships or the LV volume intercept at 0 mm Hg diastolic pressure (LV V(0) in milliliters) (castration ISO = 0.35 ± 0.02, castration saline vehicle = 0.27 ± 0.03, P < 0.05). In conclusion, castration does not influence the extent of LV dilatation induced by chronic adrenergic activation in an animal model, where adverse LV remodeling precedes LV systolic chamber dysfunction.

Androgen attenuates cardiac fibroblasts activations through modulations of transforming growth factor-β and angiotensin II signaling

BACKGROUND

Androgen deficiency produces heart failure, which can be ameliorated by testosterone supplementation. Cardiac fibrosis plays a critical role in the pathophysiology of heart failure. This study aimed to evaluate whether testosterone can attenuate cardiac fibroblast activity through modulating transforming growth factor (TGF)-β and angiotensin (Ang) II signaling.

METHODS

Migration, proliferation, myofibroblast differentiation, collagen production, and transcription signaling were evaluated in adult male rat (weighing 300-350 g) cardiac fibroblasts with and without incubation with testosterone (10nM) and co-administration of TGF-β1 (10 ng/ml) or Ang II (100 nM) by cell migration analysis, proliferation assay, soluble collagen measurement, zymographic analysis, immunofluorescence microscopy, real-time PCR and Western blot.

RESULTS

Compared to those without testosterone, testosterone-treated fibroblasts exhibited less collagen production. Testosterone-treated fibroblasts also had less migration, proliferation, myofibroblast differentiation, and collagen production in the presence of TGF-β1, or had less collagen production with Ang II. Testosterone-treated fibroblasts had decreased phosphorylated Akt, mammalian target of rapamycin, and 4E binding protein-1 irrespective of TGF-β1 treatment and had increased matrix metalloproteinase (MMP)-2 in the presence of TGF-β1 treatment, and had decreased phosphorylated P38 and Smad 2/3 levels in the presence of Ang II. Cardiac fibroblasts with and without testosterone had similar mRNA and protein expressions of total Akt and total Smad 2/3 irrespective of TGF-β1 or Ang II treatment.

CONCLUSION

Physiological level of testosterone attenuated Akt and Smad 2/3 phosphorylation mediated by TGF-β1 and angiotensin II respectively, which can result in decreased cardiac fibroblast activation and potentially contribute to beneficial effects in heart failure.

Risks of testosterone replacement therapy in men

Testosterone replacement therapy (TRT) is a widely used treatment for men with symptomatic hypogonadism. The benefits seen with TRT, such as increased libido and energy level, beneficial effects on bone density, strength and muscle as well as cardioprotective effects, have been well-documented. TRT is contraindicated in men with untreated prostate and breast cancer. Men on TRT should be monitored for side-effects such as polycythemia, peripheral edema, cardiac and hepatic dysfunction.

Serum testosterone levels and mortality in men with CKD stages 3-4

BACKGROUND

Hypogonadism in men (total testosterone <350 ng/dL) is associated with higher risk of cardiovascular disease and mortality in men on dialysis therapy. We evaluated the association of hypogonadism with all-cause mortality in men with non-dialysis-dependent chronic kidney disease (CKD).

STUDY DESIGN

Retrospective, cohort study.

SETTING & PARTICIPANTS

2,419 men with CKD stages 3-4 (estimated glomerular filtration rate, 15-59 mL/min/1.73 m2) who had total testosterone measured for cause between January 1, 2005, and October 31, 2011, at a tertiary-care center in Cleveland, OH.

PREDICTORS

Total testosterone measured using an immunoassay measurement in 3 forms: (1) categorized as low or testosterone replacement therapy versus normal, (2) continuous log testosterone, and (3) quintiles (100-226, 227-305, 306-392, 393-511, and 512-3,153 ng/dL).

OUTCOMES

Factors associated with low total testosterone level and the association between low total testosterone level and all-cause mortality were evaluated using logistic regression, Cox proportional hazard models, and Kaplan-Meier survival curves.

RESULTS

Hypogonadism was found in 1,288 of 2,419 (53%) men. In a multivariable logistic regression analysis, African American ethnicity and higher estimated glomerular filtration rate were associated with lower odds of having hypogonadism. Diabetes and higher body mass index were associated with higher odds of having hypogonadism. 357 of 2,419 (15%) patients died during a median follow-up of 2.3 years. In the multivariate Cox model, testosterone level <350 ng/dL or testosterone replacement therapy was not associated with mortality. In a multivariable model also adjusted for testosterone supplementation, higher log testosterone was associated with significantly lower mortality (HR per 1 log unit, 0.70; 95% CI, 0.55-0.89). When compared to the highest quintile, the second lowest quintile of testosterone was associated with higher mortality (HR, 1.53; 95% CI, 1.09-2.16).

LIMITATIONS

Single-center study, timing of testosterone testing, lack of adjustment for proteinuria, and sampling bias.

CONCLUSIONS

Low total testosterone level may be associated with higher mortality in men with CKD stages 3-4, but more studies are needed.

Should there be sex-specific criteria for the diagnosis and treatment of heart failure?

All-cause mortality from cardiovascular disease is declining in the USA. However, there remains a significant difference in risk factors for disease and in mortality between men and women. For example, prevalence and outcomes for heart failure with preserved ejection fraction differ between men and women. The reasons for these differences are multifactorial, but reflect, in part, an incomplete understanding of sex differences in the etiology of cardiovascular diseases and a failure to account for sex differences in pre-clinical studies including those designed to develop new diagnostic and treatment modalities. This review focuses on the underlying physiology of these sex differences and provides evidence that inclusion of female animals in pre-clinical studies of heart failure and in development of imaging modalities to assess cardiac function might provide new information from which one could develop sex-specific diagnostic criteria and approaches to treatment.