Different effects of prolonged β-adrenergic stimulation on heart and cerebral artery

An integrative review of nonobvious puzzles of cellular and molecular cardiooncology

Oncologic patients are subjected to four major treatment types: surgery, radiotherapy, chemotherapy, and immunotherapy. All nonsurgical forms of cancer management are known to potentially violate the structural and functional integrity of the cardiovascular system. The prevalence and severity of cardiotoxicity and vascular abnormalities led to the emergence of a clinical subdiscipline, called cardiooncology. This relatively new, but rapidly expanding area of knowledge, primarily focuses on clinical observations linking the adverse effects of cancer therapy with deteriorated quality of life of cancer survivors and their increased morbidity and mortality. Cellular and molecular determinants of these relations are far less understood, mainly because of several unsolved paths and contradicting findings in the literature. In this article, we provide a comprehensive view of the cellular and molecular etiology of cardiooncology. We pay particular attention to various intracellular processes that arise in cardiomyocytes, vascular endothelial cells, and smooth muscle cells treated in experimentally-controlled conditions in vitro and in vivo with ionizing radiation and drugs representing diverse modes of anti-cancer activity.

The past, present, and future physiology and pharmacology of glucagon

The evolution of glucagon has seen the transition from an impurity in the preparation of insulin to the development of glucagon receptor agonists for use in type 1 diabetes. In type 2 diabetes, glucagon receptor antagonists have been explored to reduce glycemia thought to be induced by hyperglucagonemia. However, the catabolic actions of glucagon are currently being leveraged to target the rise in obesity that paralleled that of diabetes, bringing the pharmacology of glucagon full circle. During this evolution, the physiological importance of glucagon advanced beyond the control of hepatic glucose production, incorporating critical roles for glucagon to regulate both lipid and amino acid metabolism. Thus, it is unsurprising that the study of glucagon has left several paradoxes that make it difficult to distill this hormone down to a simplified action. Here, we describe the history of glucagon from the past to the present and suggest some direction to the future of this field.

Associations between triglyceride-glucose index and different hypertension subtypes: A population-based study in China

Background

Abnormal glycolipid metabolism plays a crucial role in hypertension. While an elevated triglyceride-glucose (TyG) index has been recognized as a risk factor for developing hypertension, the associations between the TyG index and different hypertension subtypes, namely, isolated systolic hypertension (ISH), isolated diastolic hypertension (IDH), and systolic-diastolic hypertension (SDH), remain unclear. This study was designed to investigate the associations between the TyG index and hypertension subtypes in a general Chinese population.

Materials and methods

In a sample of 16,793 participants from Shandong Province, China, multivariate logistic regression analyses were performed to examine the associations between the TyG index and different hypertension subtypes. Loess smooth curves were fitted to visualize the trends. Stratified analyses were conducted to further assess the potential interactions in the associations between the TyG index and different hypertension subtypes.

Results

A higher TyG index was associated with an increased odds of having IDH (OR = 2.94, 95% CI: 1.66–5.23) and SDH (OR = 1.82, 95% CI: 1.33–2.49), whereas no apparent relationship was observed between TyG index and ISH. With respect to sex, the effect of TyG index on having IDH and SDH was significant in women, but not in men. Participants with lower lipid profiles and glucose levels demonstrated a stronger strength of association between the TyG index and IDH as compared with the TyG index-SDH association. Stratified analysis showed that participants with a higher TyG index were more than 3 times more likely to have IDH and SDH among persons aged 18–42 years. Significant interactions were observed between TyG index and sex, age, and high-density lipoprotein cholesterol (HDL-C) in the SDH group, and a significant interaction was also found between TyG index and body mass index (BMI) in the ISH group.

Conclusion

Triglyceride-glucose index may potentially serve as a novel indicator for IDH and SDH. Our findings could also inform the development and implementation of targeted screening for hypertension.

Evaluation of β-adrenergic ligands for development of pharmacological heart failure and transparency models in zebrafish

Cardiovascular toxicity represents one of the most common reasons for clinical trial failure. Consequently, early identification of novel cardioprotective strategies could prevent the later-stage drug-induced cardiac side effects. The use of zebrafish (Danio rerio) in preclinical studies has greatly increased. High-throughput and low-cost of assays make zebrafish model ideal for initial drug discovery. A common strategy to induce heart failure is a chronic β-adrenergic (βAR) stimulation. Herein, we set out to test a panel of βAR agonists to develop a pharmacological heart failure model in zebrafish. We assessed βAR agonists with respect to the elicited mortality, changes in heart rate, and morphological alterations in zebrafish larvae according to Fish Embryo Acute Toxicity Test. Among the tested βAR agonists, epinephrine elicited the most potent onset of heart stimulation (EC₅₀ = 0.05 mM), which corresponds with its physiological role as catecholamine. However, when used at ten-fold higher dose (0.5 mM), the same compound caused severe heart rate inhibition (-28.70 beats/min), which can be attributed to its cardiotoxicity. Further studies revealed that isoetharine abolished body pigmentation at the sublethal dose of 7.50 mM. Additionally, as a proof of concept that zebrafish can mimic human cardiac physiology, we tested βAR antagonists (propranolol, carvedilol, metoprolol, and labetalol) and verified that they inhibited fish heart rate in a similar fashion as in humans. In conclusion, we proposed two novel pharmacological models in zebrafish; i.e., epinephrine-dependent heart failure and isoetharine-dependent transparent zebrafish. We provided strong evidence that the zebrafish model constitutes a valuable tool for cardiovascular research.

Increased β-adrenergic stimulation augments vascular smooth muscle cell calcification via PKA/CREB signalling

In chronic kidney disease (CKD), hyperphosphatemia promotes medial vascular calcification, a process augmented by osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs). VSMC function is regulated by sympathetic innervation, and these cells express α- and β-adrenergic receptors. The present study explored the effects of β2-adrenergic stimulation by isoproterenol on VSMC calcification. Experiments were performed in primary human aortic VSMCs treated with isoproterenol during control or high phosphate conditions. As a result, isoproterenol dose dependently up-regulated the expression of osteogenic markers core-binding factor α-1 (CBFA1) and tissue-nonspecific alkaline phosphatase (ALPL) in VSMCs. Furthermore, prolonged isoproterenol exposure augmented phosphate-induced calcification of VSMCs. Isoproterenol increased the activation of PKA and CREB, while knockdown of the PKA catalytic subunit α (PRKACA) or of CREB1 genes was able to suppress the pro-calcific effects of isoproterenol in VSMCs. β2-adrenergic receptor silencing or inhibition with the selective antagonist ICI 118,551 blocked isoproterenol-induced osteogenic signalling in VSMCs. The present observations imply a pro-calcific effect of β2-adrenergic overstimulation in VSMCs, which is mediated, at least partly, by PKA/CREB signalling. These observations may support a link between sympathetic overactivity in CKD and vascular calcification.

Effects of hormone replacement therapy on left ventricular diastolic function in postmenopausal women: a systematic review and meta-analysis

BACKGROUND

Postmenopausal women tend to experience significant changes in left ventricular diastolic function (LVDF). However, there are conflicting reports about LVDF between postmenopausal women on hormone replacement therapy (HRT) and those not on HRT. This meta-analysis is to evaluate the effects of HRT on LVDF in postmenopausal women.

METHODS

We conducted a systemic review of randomized controlled trials published up to December 31 2019 using Embase, Pubmed, and the Cochrane library database.

RESULTS

Eight studies involving 668 postmenopausal women were identified. Our analysis indicated that the ratio of the peak velocity during early filing to late filling from atrial contraction improvement in HRT group was better than that in placebo group (MD 0.20, 95%CI 0.12 to 0.28). There was a significant reduction in deceleration time and left ventricular mass index in HRT group compared with placebo group (MD -21.01, 95%CI -40.11 to -1.91 vs MD -8.26, 95%CI -14.10 to -2.42). No significant difference was observed in left ventricular end systole diameter (MD 0.80, 95%CI -0.72 to 2.31), left ventricular end diastole diameter (MD -0.07, 95%CI -1.25 to 1.10), left atrial size (MD -0.33, 95%CI -1.34 to 0.68)and the isovolumic relaxation time (MD -12.08, 95%CI -27.65 to 3.5).

CONCLUSIONS

Our meta-analysis illustrated that postmenopausal women seem to obtain more beneficial effects from HRT on LVDF, though future studies are required to elucidate the specific mechanisms for this phenomenon.

β-Adrenergic receptor, an essential target in cardiovascular diseases

β-Adrenergic receptors (βARs) belong to a large family of cell surface receptors known as G protein-coupled receptors (GPCRs). They are coupled to Gs protein (Gαs) for the activation of adenylyl cyclase (AC) yielding cyclic AMP (_CAMP), and this provides valuable responses, which can affect the cardiac function such as injury. The binding of an agonist to βAR enhances conformation changes that lead to the Gαs subtype of heterotrimeric G protein which is the AC stimulatory G protein for activation of _CAMP in the cells. However, cardiovascular diseases (CVD) have been reported as having an increased rate of death and β1AR, and β2AR are a promising tool that improves the regulatory function in the cardiovascular system (CVS) via signaling. It increases the Gα level, which activates βAR kinase (βARK) that affects and enhances the progression of heart failure (HF) through the activation of cardiomyocyte βARs. We also explained that an increase in GPCR kinases (GRKs) would practically improve the HF pathogenesis and this occurs via the desensitization of βARs, which causes the loss of contractile reserve. The consistency or overstimulation of catecholamines contributes to CVD such as stroke, HF, and cardiac hypertrophy. When there is a decrease in catecholamine responsiveness, it causes aging in old people because the reduction of βAR sensitivity and density in the myocardium enhances downregulation of βARs to AC in the human heart.

Binge Alcohol Exposure in Adolescence Impairs Normal Heart Growth

Background

Approximately 1 in 6 adolescents report regular binge alcohol consumption, and we hypothesize it affects heart growth during this period.

Methods and Results

Adolescent, genetically diverse, male Wistar rats were gavaged with water or ethanol once per day for 6 days. In vivo structure and function were assessed before and after exposure. Binge alcohol exposure in adolescence significantly impaired normal cardiac growth but did not affect whole‐body growth during adolescence, therefore this pathology was specific to the heart. Binge rats also exhibited signs of accelerated pathological growth (concentric cellular hypertrophy and thickening of the myocardial wall), suggesting a global reorientation from physiologic to pathologic growth. Binge rats compensated for their smaller filling volumes by increasing systolic function and sympathetic stimulation. Consequently, binge alcohol exposure increased PKA (protein kinase A) phosphorylation of troponin I, inducing myofilament calcium desensitization. Binge alcohol also impaired in vivo relaxation and increased titin‐based cellular stiffness due to titin phosphorylation by PKCα (protein kinase C α). Mechanistically, alcohol inhibited extracellular signal‐related kinase activity, a nodal signaling kinase activating physiology hypertrophy. Thus, binge alcohol exposure depressed genes involved in growth. These cardiac structural alterations from binge alcohol exposure persisted through adolescence even after cessation of ethanol exposure.

Conclusions

Alcohol negatively impacts function in the adult heart, but the adolescent heart is substantially more sensitive to its effects. This difference is likely because adolescent binge alcohol impedes the normal rapid physiological growth and reorients it towards pathological hypertrophy. Many adolescents regularly binge alcohol, and here we report a novel pathological consequence as well as mechanisms involved.

Isosteviol prevents the development of isoprenaline‑induced myocardial hypertrophy

Isosteviol sodium (STVNa), which is a derivate of the natural sweet-tasting glycoside stevioside, has recently been developed and it has been determined that this compound exhibits neuro- and cardio-protective properties. In the current study, whether STVNa interferes with the development of cardiac hypertrophy, which is induced by isoprenaline (Iso), was investigated in an experimental rat model. Rats were treated with a vehicle (0.9% NaCl; control), isoprenaline (Iso; 5 mg/kg) or Iso (5 mg/kg) with STVNa (4 mg/kg; Iso + STVNa). Cardiomyocytes were isolated using enzymatic dissociation and were treated with 5 µM Iso for 24 h and co-treated with 5 µM STVNa. Brain natriuretic peptide (BNP) mRNA expression was determined using PCR analysis. Cell surface area, intracellular reactive oxygen species (ROS), mitochondrial transmembrane potential (ΔΨm), cytoplasmic Ca²⁺ and Ca²⁺ and contractile function were examined using a laser scanning confocal microscope. The current study demonstrated that STVNa inhibited Iso-induced cardiac hypertrophy by inhibiting cardiomyocyte size. STVNa significantly reduced cell surface area and decreased BNP mRNA expression in ventricular cardiomyocyte Iso-induced hypertrophy. STVNa was also revealed to restore ΔΨm and reduce ROS generation and intracellular Ca²⁺ concentration when compared with the Iso-treated group. Additionally, STVNa preserved Ca²⁺ transients in hypertrophic cardiomyocytes. In conclusion, the present study demonstrated that STVNa protects against Iso-induced myocardial hypertrophy by reducing oxidative stress, restoring ΔΨm and maintaining Ca²⁺ homeostasis.

Hurdles to Cardioprotection in the Critically Ill

Cardiovascular disease is the largest contributor to worldwide mortality, and the deleterious impact of heart failure (HF) is projected to grow exponentially in the future. As heart transplantation (HTx) is the only effective treatment for end-stage HF, development of mechanical circulatory support (MCS) technology has unveiled additional therapeutic options for refractory cardiac disease. Unfortunately, despite both MCS and HTx being quintessential treatments for significant cardiac impairment, associated morbidity and mortality remain high. MCS technology continues to evolve, but is associated with numerous disturbances to cardiac function (e.g., oxidative damage, arrhythmias). Following MCS intervention, HTx is frequently the destination option for survival of critically ill cardiac patients. While effective, donor hearts are scarce, thus limiting HTx to few qualifying patients, and HTx remains correlated with substantial post-HTx complications. While MCS and HTx are vital to survival of critically ill cardiac patients, cardioprotective strategies to improve outcomes from these treatments are highly desirable. Accordingly, this review summarizes the current status of MCS and HTx in the clinic, and the associated cardiac complications inherent to these treatments. Furthermore, we detail current research being undertaken to improve cardiac outcomes following MCS/HTx, and important considerations for reducing the significant morbidity and mortality associated with these necessary treatment strategies.

Acute metabolic and cardiovascular effects of mirabegron in healthy individuals

AIMS

To quantify acute energy expenditure, supraclavicular skin temperature and cardiovascular responses to four doses of the β3-adrenoceptor agonist, mirabegron.

MATERIALS AND METHODS

A total of 17 individuals (11 men, six women) participated in this ascending-dose study, receiving single 50-, 100-, 150- and 200-mg doses of mirabegron on four separate days with 3 to 14 days wash-out between each dose. All variables were measured each visit from baseline to 180 minutes post mirabegron treatment. To determine brown adipose tissue (BAT) thermogenic efficacy at each dose, energy expenditure and supraclavicular skin temperature were compared from baseline to 180 minutes post mirabegron treatment. To examine safety, changes in cardiovascular variables at 100, 150 and 200 mg were compared with the standard clinical dose of 50 mg.

RESULTS

Energy expenditure significantly increased after the 100- (35.6 ± 5.4 kJ/h) and 200-mg (35.6 ± 13.1 kJ/h) doses (P ≤ 0.05), and trended towards an increase after 150 mg (24.1 ± 13.6 kJ/h). Supraclavicular skin temperature increased after 50- (0.22 ± 0.1°C), 100- (0.30 ± 0.1°C) and 150-mg mirabegron doses (0.29 ± 0.1°C; P ≤ 0.05). The change in systolic blood pressure was greater after 150- (7.1 ± 1.3 mm Hg) and 200-mg doses (9.3 ± 1.9 mm Hg) than after the 50-mg dose (2.2 ± 1.3 mm Hg; P ≤ 0.05). The change in heart rate was greater after 200 mg (9.0 ± 2.2 bpm) compared with 50 mg (2.9 ± 1.4 bpm; P ≤ 0.05).

CONCLUSIONS

A 100-mg dose of mirabegron increases energy expenditure and supraclavicular skin temperature in a β3-adrenoceptor-specific manner, without the off-target elevations in blood pressure or heart rate observed at higher doses.

Blockade of AT1 type receptors for angiotensin II prevents cardiac microvascular fibrosis induced by chronic stress in Sprague-Dawley rats

To test the effects of chronic-stress on the cardiovascular system, the model of chronic mild unpredictable stress (CMS) has been widely used. The CMS protocol consists of the random, intermittent, and unpredictable exposure of laboratory animals to a variety of stressors, during 3 consecutive weeks. In this study, we tested the hypothesis that exposure to the CMS protocol leads to left ventricle microcirculatory remodeling that can be attenuated by angiotensin II receptor blockade. Male Sprague-Dawley rats were randomly assigned into four groups: Control, Stress, Control + losartan, and Stress + losartan (N = 6, each group, losartan: 20 mg/kg/day). The rats were euthanized 15 days after CMS exposure, and blood samples and left ventricle were collected. Rats submitted to CMS presented increased glycemia, corticosterone, noradrenaline and adrenaline concentration, and losartan reduced the concentration of the circulating amines. Cardiac angiotensin II, measured by high-performance liquid chromatography (HPLC), was significantly increased in the CMS group, and losartan treatment reduced it, while angiotensin 1-7 was significantly higher in the CMS losartan-treated group as compared with CMS. Histological analysis, verified by transmission electron microscopy, showed that rats exposed to CMS presented increased perivascular collagen and losartan effectively prevented the development of this process. Hence, CMS induced a state of microvascular disease, with increased perivascular collagen deposition, that may be the trigger for further development of cardiovascular disease. In this case, CMS fibrosis is associated with increased production of catecholamines and with a disruption of renin-angiotensin system balance, which can be prevented by angiotensin II receptor blockade.

Pin1 facilitates isoproterenol‑induced cardiac fibrosis and collagen deposition by promoting oxidative stress and activating the MEK1/2‑ERK1/2 signal transduction pathway in rats

Peptidyl-prolyl cis/trans isomerase, NIMA-interacting 1 (Pin1) is a member of a large superfamily of phosphorylation-dependent peptidyl-prolyl cis/trans isomerases, which not only regulates multiple targets at various stages of cellular processes, but is also involved in the pathogenesis of several diseases, including microbial infection, cancer, asthma and Alzheimer's disease. However, the role of Pin1 in cardiac fibrosis remains to be fully elucidated. The present study investigated the potential mechanism of Pin1 in isoprenaline (ISO)-induced myocardial fibrosis in rats. The rats were randomly divided into three groups. Echocardiography was used to evaluate changes in the size, shape and function of the heart, and histological staining was performed to visualize inflammatory cell infiltration and fibrosis. Reverse transcription-quantitative polymerase chain reaction analysis, immunohistochemistry and Picrosirius red staining were used to differentiate collagen subtypes. Additionally, cardiac-specific phosphorylation of mitogen-activated protein kinase kinase 1/2 (MEK1/2) and extracellular-signal regulated protein kinase 1/2 (ERK1/2), and the activities of Pin1 and α-smooth muscle actin (α-SMA) and other oxidative stress parameters were estimated in the heart. The administration of ISO resulted in an increase in cardiac parameters and elevated the heart-to-body weight ratio. Histopathological examination of heart tissues revealed interstitial inflammatory cellular infiltrate and disorganized collagen fiber deposition. In addition, lipid peroxidation products and oxidative stress marker activity in plasma and tissues were significantly increased in the ISO-treated rats. Western blot analysis showed significantly elevated protein levels of phosphorylated Pin1, MEK1/2, ERK1/2 and α-SMA in remodeling hearts. Treatment with juglone following intraperitoneal injection of ISO significantly prevented inflammatory cell infiltration, improved cardiac function, and suppressed oxidative stresses and fibrotic alterations. In conclusion, the results of the present study suggested that the activation of Pin1 promoted cardiac extracellular matrix deposition and oxidative stress damage by regulating the phosphorylation of the MEK1/2-ERK1/2 signaling pathway and the expression of α-SMA. By contrast, the inhibition of Pin1 alleviated cardiac damage and fibrosis in the experimental models, suggesting that Pin1 contributed to the development of cardiac remodeling in ISO-administered rats, and that the inactivation of Pin1 may be a novel therapeutic candidate for the treatment of cardiovascular disease and heart failure.

Coenzyme Q10 prevents oxidative stress and fibrosis in isoprenaline induced cardiac remodeling in aged rats

Background

The objective of the present study aimed to investigate the effect of CoQ10 treatment on isoprenaline (ISO)-induced cardiac remodeling in rats.

Methods

Rats were divided into three groups namely Control group, ISO treated group and CoQ10 + ISO treated group, each consisting of 6 rats. The cardiac specific CK-MB, AST, ALT activity and other oxidative stress parameters were estimated in heart and kidneys. Additionally histological examination was also performed to visualize the inflammatory cells infiltration and fibrosis in both tissues.

Results

Administration of ISO resulted in an increase in the heart-to-body weight (HW/BW) ratio and an also increased the serum CK-MB, AST and ALT enzyme activity. Serum levels of lipid peroxidation products, and oxidative stress markers showed significant increase in ISO-treated rats. Histopathological examination of heart tissue revealed focal areas of endocardium degeneration, mononuclear cells infiltration, fibrous tissue deposition, and increased thickness of the myocardium of left ventricle. Similar degeneration was also found in kidneys. Treatment with CoQ10 (100 mg/kg) significantly improved the oxidative stresses in ISO treated rats. Moreover, CoQ10 treatment prevented inflammatory cells infiltration and reduced fibrosis in ISO administered rats.

Conclusion

In conclusion, our study provides evidence that CoQ10 may prevent the development of cardiac remodeling, and fibrosis in ISO administered rats.