Abdominal Aortic Constriction Research Articles

Knockdown of TUG1 rescues cardiomyocyte hypertrophy through targeting the miR-497/MEF2C axis.

The aim of this study was to investigate the detailed role and molecular mechanism of long noncoding RNA (lncRNA) taurine upregulated gene 1 (TUG1) in cardiac hypertrophy. Cardiac hypertrophy was established by transverse abdominal aortic constriction (TAC) in vivo or angiotensin II (Ang II) treatment in vitro. Levels of lncRNA TUG1, miR-497 and myocyte enhancer factor 2C (MEF2C) mRNA were assessed by quantitative reverse transcriptase PCR (qRT-PCR). Western blot assay was performed to determine the expression of MEF2C protein. The endogenous interactions among TUG1, miR-497 and MEF2C were confirmed by dual-luciferase reporter and RNA immunoprecipitation assays. Our data indicated that TUG1 was upregulated and miR-497 was downregulated in the TAC rat model and Ang II-induced cardiomyocytes. TUG1 knockdown or miR-497 overexpression alleviated the hypertrophy induced by Ang II in cardiomyocytes. Moreover, TUG1 acted as a sponge of miR-497, and MEF2C was directly targeted and repressed by miR-497. miR-497 overexpression mediated the protective role of TUG1 knockdown in Ang II-induced cardiomyocyte hypertrophy. MEF2C was a functional target of miR-497 in regulating Ang II-induced cardiomyocyte hypertrophy. In addition, TUG1 regulated MEF2C expression through sponging miR-497. Knockdown of TUG1 rescued Ang II-induced hypertrophy in cardiomyocytes at least partly through targeting the miR-497/MEF2C axis, highlighting a novel promising therapeutic target for cardiac hypertrophy treatment.

Pinoresinol diglucoside (PDG) attenuates cardiac hypertrophy via AKT/mTOR/NF-κB signaling in pressure overload-induced rats

Ethnopharmacological relevancePinoresinol diglucoside (PDG), the active compound extracted from Eucommia ulmoides, Styrax sp. and Forsythia suspensa, plays the roles in regulating hypertension, inflammation and oxidative stress. AimsConsidering that hypertension and inflammation has been proved to contribute to cardiac remodeling, we tested the effects of PDG on cardiac hypertrophy (CM). MethodsMale Sprague Dawley (SD) rats were used to construct hypertrophic rats by partial abdominal aortic constriction (AAC)-surgery. PDG solution (2 mg/ml) was used to treat AAC-induced rats by intraperitoneal injection at low dose (L-PDG, 2.5 mg/kg per day), medium dose (M-PDG, 5 mg/kg per day), and high dose (H-PDG, 7.5 mg/kg per day) for 3 weeks post AAC-surgery. CM was evaluated by the ratio of left ventricular weight to body weight ratio (LVW/BW), left ventricular wall thickness by H&E staining, and collagen content deposit by Masson's staining. Further, isoproterenol (ISO) and phenylephrine (PE) were used to produce cellular models of CM in neonatal rat ventricular cardiomyocytes (NRVMs). PDG pre-treated NRVMs 2 h at low dose (L-PDG, 2.5 μg/ml), medium dose (M-PDG, 5 μg/ml), and high dose (H-PDG, 7.5 μg/ml) for 24 h with or without PE- and ISO-stimulation. CM was evaluated by the expressions of hypertrophic biomarkers. Next, the hypertrophic biomarkers and pro-inflammatory cytokines were measured using quantitative real-time PCR (qRT-PCR), the expressions of protein kinase B (AKT)/mammalian target of rapamycin (mTOR)/transcription factor nuclear factor-kappa B (NF-kB) signaling pathway were determined by Western blotting. ResultsPDG treatment prevented cardiac histomorphology damages, decreased upregulations of hypertrophic biomarkers, and prevented fibrosis and inflammation after pressure overload resulting from AAC-surgery. Consistently, PDG remarkably inhibited the changes of cardiomyocyte hypertrophic biomarkers and inflammatory responses in cellular models of CM. Interestingly, PDG administration inhibited the activation of AKT/mTOR/NF-kB signaling pathway both in vivo and in vitro. ConclusionsPDG prevents AAC-induced CM in vivo, PE- and ISO-induced CM in vitro. The AKT/mTOR/NF-kB signaling pathway could be the potential therapeutic target involved in the protection of PDG. These findings provide novel evidence that PDG might be a promising therapeutic strategy for CM.

QiShenYiQi pill activates autophagy to attenuate reactive myocardial fibrosis via the PI3K/AKT/mTOR pathway.

QiShenYiQi pill (QSYQ), a traditional Chinese medicine, is used to treat cardiovascular diseases. However, the dose-effect relationship of its intervention in the reactive myocardial fibrosis is elusive. In this work, rat models of reactive myocardial fibrosis induced by partial abdominal aortic coarctation were constructed and randomly classified into the model group, 3-methyladenine group, rapamycin group, QSYQ low-dose group, QSYQ medium-dose group, QSYQ high-dose group, and sham-operated rats (control group). We revealed that QSYQ lowered the heart mass index (HMI), left ventricular mass index (LVMI), and myocardial collagen volume fraction (CVF) levels in a dose-dependent mechanism. Additionally, QSYQ increased the number of autophagosomes, and the expression of myocardial Beclin-1 and LC3B. In contrast, it reduced the expression of myocardial p62 and decreased the ratios of myocardial p-PI3K/PI3K, p-Akt/Akt, and p-mTOR/mTOR. In conclusion, our results have revealed that QSYQ impacts anti-reactive myocardial fibrosis in a dose-dependent mechanism which is mediated by the activation of myocardial autophagy via the PI3K/AKT/mTOR pathway.

Elucidation of the mechanism of action of pinitol against pressure overload-induced cardiac hypertrophy and fibrosis in an animal model of aortic stenosis.

The long-term imposition of pressure overload on the cardiac tissue causes left ventricular hypertrophy (LVH) and cardiac fibrosis. Pinitol has been reported to possess antioxidant potential. The aim was to evaluate the efficacy of pinitol against pressure overload-induced cardiac hypertrophy and fibrosis in the aortic stenosis (AS) rat model. Cardiac hypertrophy was produced in Sprague-Dawley rats by abdominal aortic constriction and treated with lisinopril (15 mg/kg) or pinitol (5, 10, and 20 mg/kg). Pressure overload-induced alterations in hemodynamic and left ventricular function tests, cardiac SOD, GSH, MDA, NO, Na-K-ATPase, and mitochondrial complex enzyme levels were significantly attenuated by pinitol. The upregulated mRNA expressions of cardiac ANP, BNP, cTn-I, TNF-α, IL-1β, IL-6, Bax, Caspase-3, collagen-I, and cardiac apoptosis were markedly downregulated by pinitol. In conclusion, pinitol ameliorated pressure overload-induced LVH and fibrosis via its anti-inflammatory, antioxidant, antifibrotic, and antiapoptotic potential in experimental AS.

Zonisamide alleviates cardiac hypertrophy in rats by increasing Hrd1 expression and inhibiting endoplasmic reticulum stress.

Antiepileptic drug zonisamide has been shown to be curative for Parkinson's disease (PD) through increasing HMG-CoA reductase degradation protein 1 (Hrd1) level and mitigating endoplasmic reticulum (ER) stress. Hrd1 is an ER-transmembrane E3 ubiquitin ligase, which is involved in cardiac dysfunction and cardiac hypertrophy in a mouse model of pressure overload. In this study, we investigated whether zonisamide alleviated cardiac hypertrophy in rats by increasing Hrd1 expression and inhibiting ER stress. The beneficial effects of zonisamide were assessed in two experimental models of cardiac hypertrophy: in rats subjected to abdominal aorta constriction (AAC) and treated with zonisamide (14, 28, 56 mg · kg-1 · d-1, i.g.) for 6 weeks as well as in neonatal rat cardiomyocytes (NRCMs) co-treated with Ang II (10 μM) and zonisamide (0.3 μM). Echocardiography analysis revealed that zonsiamide treatment significantly improved cardiac function in AAC rats. We found that zonsiamide treatment significantly attenuated cardiac hypertrophy and fibrosis, and suppressed apoptosis and ER stress in the hearts of AAC rats and in Ang II-treated NRCMs. Importantly, zonisamide markedly increased the expression of Hrd1 in the hearts of AAC rats and in Ang II-treated NRCMs. Furthermore, we demonstrated that zonisamide accelerated ER-associated protein degradation (ERAD) in Ang II-treated NRCMs; knockdown of Hrd1 abrogated the inhibitory effects of zonisamide on ER stress and cardiac hypertrophy. Taken together, ourresults demonstrate that zonisamide is effective in preserving heart structure and function in the experimental models of pathological cardiac hypertrophy. Zonisamide increases Hrd1 expression, thus preventing cardiac hypertrophy and improving the cardiac function of AAC rats.

Rutaecarpine Ameliorates Pressure Overload Cardiac Hypertrophy by Suppression of Calcineurin and Angiotensin II

Cardiac hypertrophy is a major pathological process to result in heart failure and sudden death. Rutaecarpine, a pentacyclic indolopyridoquinazolinone alkaloid extracted from Evodia rutaecarpa with multiple pharmacological activities, yet the underlying protective effects and the mechanisms on cardiac hypertrophy remain unclear. This study aimed to evaluate the potential effects of rutaecarpine on pressure overload cardiac hypertrophy. Cardiac hypertrophy in rat was developed by abdominal aortic constriction (AAC) for 4 weeks, which was improved by rutaecarpine supplementation (20 or 40 mg/kg/day, i.g.) for another 4 weeks. The level of angiotensin II was increased; the mRNA expression and the activity of calcineurin in the left ventricular tissue were augmented following cardiac hypertrophy. Rutaecarpine administration decreased angiotensin II content and reduced calcineurin expression and activity. Noteworthily, in angiotensin II-induced cardiomyocytes, rutaecarpine ameliorated the hypertrophic effects in a dose-dependent manner and downregulated the increased mRNA expression and activity of calcineurin. In conclusion, rutaecarpine can improve cardiac hypertrophy in pressure overload rats, which may be related to the inhibition of angiotensin II-calcineurin signal pathway.

EGCG inhibits pressure overload-induced cardiac hypertrophy via the PSMB5/Nmnat2/SIRT6-dependent signalling pathways.

Epigallocatechin-3-gallate (EGCG), the major polyphenol found in green tea, exerts multiple protective effects against cardiovascular diseases, including cardiac hypertrophy. However, the molecular mechanism underlying its anti-hypertrophic effect has not been clarified. This study revealed that EGCG could inhibit pressure overload-induced cardiac hypertrophy by regulating the PSMB5/Nmnat2/SIRT6-dependent signalling pathway. Quantitative real-time polymerase chain reaction and western blotting were used to determine the expression of mRNA and protein respectively. A fluorometric assay kit was used to determine the activity of SIRT6, a histone deacetylase. Luciferase reporter gene assay and electrophoretic mobility shift assay were employed to measure transcriptional activity and DNA binding activity respectively. EGCG could significantly increase Nmnat2 protein expression and enzyme activity in cultured neonatal rat cardiomyocytes stimulated with angiotensin II (Ang II) and heart tissues from rats subjected to abdominal aortic constriction. Nmnat2 knockdown by RNA interference attenuated the inhibitory effect of EGCG on cardiac hypertrophy. EGCG blocked NF-κB DNA binding activity induced by Ang II, which was dependent on Nmnat2 and the subsequent SIRT6 activation. Moreover the activation of PSMB5 (20S proteasome subunit β-5, chymotrypsin-like) was required for EGCG-induced Nmnat2 protein expression. Additionally, we demonstrated that EGCG might interact with PSMB5 and inhibit the activation of the proteasome. These findings serve as the first evidence that the effect of EGCG against cardiac hypertrophy may be, at least partially, attributed to the modulation of the PSMB5/Nmnat2-dependent signalling pathway, suggesting the therapeutic potential of EGCG in the prevention and treatment of cardiac hypertrophy.

Water-soluble alkaloids extracted from Aconiti Radix lateralis praeparata protect against chronic heart failure in rats via a calcium signaling pathway

Ethnopharmacological relevanceMany studies have shown the beneficial effects of aconite water-soluble alkaloid extract (AWA) in experimental models of heart disease, which have been ascribed to the presence of aconine, hypaconine, talatisamine, fuziline, neoline, and songorine. This study evaluated the effects of a chemically characterized AWA by chemical content, evaluated its effects in suprarenal abdominal aortic coarctation surgery (AAC)-induced chronic heart failure (CHF) in rats, and revealed the underlying mechanisms of action by proteomics. MethodsRats were distributed into different groups: sham, model, and AWA-treated groups (10, 20, and 40 mg/kg/day). Sham rats received surgery without AAC, whereas model rats an AWA-treated groups underwent AAC surgery. after 8 weeks, the treatment group was fed AWA for 4 weeks, and body weight was assessed weekly. At the end of the treatment, heart function was tested by echocardiography. AAC-induced chronic heart failure, including myocardial fibrosis, cardiomyocyte hypertrophy, and apoptosis, was evaluated in heart tissue and plasma by RT-qPCR, ELISA, hematoxylin and eosin (H&E) staining, Masson's trichrome staining, TUNEL staining, and immunofluorescence staining of α-SMA, Col Ⅰ, and Col Ⅲ. Then, a proteomics approach was used to explore the underlying mechanisms of action of AWA in chronic heart failure. ResultsAWA administration reduced body weight gain, myocardial fibrosis, cardiomyocyte hypertrophy, and apoptosis, and rats showed improvement in cardiac function compared to model group. The extract significantly ameliorated the AAC-induced altered expression of heart failure markers such as ANP, NT-proBNP, and β-MHC, as well as fibrosis, hypertrophy markers MMP-2 and MMP-9, and other heart failure-related factors including plasma levels of TNF-α and IL-6. Furthermore, the extract reduced the protein expression of α-SMA, Col Ⅰ, and Col Ⅲ in the left ventricular (LV), thus inhibiting the LV remodeling associated with CHF. In addition, proteomics characterization of differentially expressed proteins showed that AWA administration inhibited left ventricular remodeling in CHF rats via a calcium signaling pathway, and reversed the expression of RyR2 and SERCA2a. ConclusionsAWA extract exerts beneficial effects in an AAC-induced CHF model in rats, which was associated with an improvement in LV function, hypertrophy, fibrosis, and apoptotic status. These effects may be related to the regulation of calcium signaling by the altered expression of RyR2 and SERCA2a.

Effects of ginsenoside Rb1 on serum brain natriuretic peptide level and caspase-3 protein expression in cardiomyocytes of rats with chronic heart failure

Context: Ginsenoside Rb1 is a representative ginsenoside, and caspase-3 is implicated in chronic heart failure (CHF). Aim: The aim of this study was to evaluate the effects of ginsenoside Rb1 on the level of brain natriuretic peptide (BNP) in serum and the expression of caspase-3 protein in the cardiomyocytes of CHF rats. Subjects and Methods: A total of 48 Wistar rats were divided into control, model, positive control (losartan), and ginsenoside Rb1 groups at random (n = 12). Abdominal aortic constriction was adopted for CHF modeling. Four weeks after surgery, ginsenoside Rb1 and losartan groups were intragastrically administered with 50 mg/kg ginsenoside Rb1 and 4.5 mg/kg losartan daily, respectively. Control and model groups were given equal volumes of distilled water. Cardiac function indices, electrocardiographic signals, BNP level, heart weight, body weight, heart-to-body weight ratio, myocardial pathological changes, and caspase-3 protein expression were compared. Results: In contrast to model group, heart rate, left ventricular end-diastolic pressure, BNP level, and caspase-3 protein expression of ginsenoside Rb1 and losartan groups notably dropped, whereas left ventricular systolic pressure and maximal rise/fall rate of the left ventricular pressure significantly rose (P < 0.05). The heart weight and heart-to-body weight ratio of ginsenoside Rb1 and losartan groups were evidently lower relative to those in the model group (P < 0.05). The ST segments of losartan and ginsenoside Rb1 groups fell after rise. Ginsenoside Rb1 inhibited focal cardiomyocyte necrosis and steatosis and relieved myocardial myofibrillar dissolution. It evidently decreased broken muscle bundles, as well as alleviated fibrosis and myocardial fibrosis. Conclusion: Ginsenoside Rb1 can improve the cardiac function of CHF rats, probably by inhibiting the apoptosis of cardiomyocytes.

Dickkopf-1 promotes Vascular Smooth Muscle Cell proliferation and migration through upregulating UHRF1 during Cyclic Stretch application.

Dickkopf-1 (DKK1) was recently shown to play an important role in cardiovascular disease. The aim of this work was to assess the role of DKK1 in the regulation of smooth muscle cell function by mechanical stretch and the mechanisms underlying this process.Methods: Wild-type C57BL/6J mice were subjected to sham or abdominal aortic constriction (AAC) surgery. The expression level of DKK1 was examined by immunohistochemical staining and Western blotting. Analyses of DKK1 function in vascular smooth muscle cell (VSMC) proliferation and migration were performed. Transcriptome sequencing analysis was performed to identify the differentially expressed genes and pathways regulated by DKK1. Smooth muscle-specific Dkk1 knockout mice were used to confirm the function of DKK1 in vivo. Chromatin immunoprecipitation (ChIP) was used to confirm DNA-protein interactions. Promoter luciferase analysis was used to detect transcription factor activity.Results: We found that AAC significantly increased DKK1 protein levels in the thoracic aorta and coronary artery in vivo. In vitro, high-level stretch (18%) induced the expression of DKK1 in VSMCs. Knocking down DKK1 inhibited VSMC proliferation and migration under high-level stretch (18%). We identified ubiquitin-like containing PHD and RING finger domains 1 (UHRF1) as a target gene of DKK1. Knockdown of UHRF1 with small interfering RNAs partially reversed the regulatory effect of recombinant DKK1 on VSMCs. Specific deletion of DKK1 in VSMCs was sufficient to attenuate the AAC-induced upregulation of UHRF1, thickening of arterial media and increase in VSMC proliferation. Furthermore, we found that DKK1 regulated UHRF1 expression through the YAP-TEAD pathway. TEAD1 and TEAD4 bound directly to the promoter of UHRF1, and blocking the YAP-TEAD interaction inhibited UHRF1 upregulation due to DKK1.Conclusions: This study reveals that DKK1 mediates the mechanical stretch regulation of smooth muscle cell function by modulating UHRF1 expression through the YAP-TEAD pathway.

Neuropeptide Y mediates cardiac hypertrophy through microRNA-216b/FoxO4 signaling pathway.

Cardiac hypertrophy (CH) is a major risk factor for heart failure accompanied by maladaptive cardiac remodeling. The role and potential mechanism of neuropeptide Y (NPY) in CH are still unclear. We will explore the role and the mechanism of NPY inactivation (NPY-I) in CH caused by pressure overload. Abdominal aortic constriction (AAC) was used to induce CH model in rats. NPY or angiotensin II (Ang II) was used to trigger CH model in vitro in neonatal rat ventricular myocytes (NRVMs). We found that NPY was increased in the heart and plasma of hypertrophic rats. However, Ang II did not increase NPY expression in cardiomyocytes. NPY-I attenuated CH as decreasing CH-related markers (ANP, BNP and β-MHC mRNA) level, reducing cell surface area, and restoring cardiac function. NPY inactivation increased miR-216b and decreased FoxO4 expression in CH heart. Moreover, NPY decreased miR-216b and increased FoxO4 expression in NRVMs which were reversed by NPY type 1 receptor (NPY1R) antagonist BIBO3304. MiR-216b mimic and FoxO4 siRNA (small interfering RNA) inhibited NPY/Ang II-induced myocardial hypertrophy in vitro. Meanwhile, BIBO3304 reversed the pro-hypertrophy effect of NPY in vitro. Collectively, NPY deficiency attenuated CH by NPY1R-miR-216b-FoxO4 axis. These findings suggested that NPY would be a potential therapeutic target for the prevention and treatment of cardiac hypertrophy.

Upregulation of iNOS Protects Cyclic Mechanical Stretch-Induced Cell Death in Rat Aorta Smooth Muscle Cells.

Aortic dissection and aneurysm are associated with abnormal hemodynamic loads originating from hypertension. Our previous study demonstrated that cyclic mechanical stretch (CMS, mimicked hypertension) caused the death of rat aortic smooth muscle cells (RASMCs) in a mitogen activated-protein kinases (MAPKs)-dependent manner. The current study investigated the effects of inducible nitric oxide synthase (iNOS) on CMS-induced RASMC death. cDNA microarrays for CMS-treated RASMCs showed that iNOS expression levels were increased in response to CMS. Real-time polymerase chain reaction (PCR) analysis demonstrated that this increase was p38 MAPK (p38)-dependent. NO production was also increased. This increase could be inhibited by p38 and iNOS inhibitors. Thus, CMS-induced iNOS synthesized NO. CMS-induced cell death in RASMCs was increased by the iNOS inhibitor but abrogated by the long-acting NO donor DETA-NONOate. Increased iNOS expression was confirmed in the abdominal aortic constriction mouse model. Signal transducers and activators of transcription 1 (STAT1) was activated in stretched RASMCs, and iNOS expression and NO production were inhibited by the STAT1 inhibitor nifuroxazide. Our findings suggest that RASMCs were protected by iNOS from CMS-stimulated cell death through the STAT1 and p38 signal pathways independently.

Ghrelin inhibited pressure overload–induced cardiac hypertrophy by promoting autophagy via CaMKK/AMPK signaling pathway

Ghrelin, a novel gut hormone, has been shown to exert protective effects on cardiac dysfunction and remodeling. However, the underlying mechanisms of its protective effects remain unclear. Here, we investigated the effects of ghrelin on cardiac hypertrophy and explored the mechanisms involved. Ghrelin (30 μg.kg−1. day−1) was systemically administered to rats with cardiac hypertrophy induced by abdominal aortic constriction (AAC) by a mini-osmotic pump the next day after surgery continuously for 4 weeks. The AAC treated rats without ghrelin infusion showed decreased ghrelin content and expression of its receptors in the hearts. Exogenous ghrelin greatly attenuated cardiac hypertrophy as shown by heart weight to tibial length (HW/TL), hemodynamics, echocardiography, histological analyses, and expression of hypertrophic markers induced by AAC. This corresponded with decreased cardiac fibrosis and inflammation in the hearts of AAC rats treated with ghrelin. Moreover, ghrelin significantly increased the myocardial expression of autophagy markers, which was further confirmed in cultured cardiomyocytes. Concurrently, cardiomyocyte apoptosis in vivo and in vitro was ameliorated by ghrelin, which was reversed by inhibition of autophagy. The enhancement of autophagy and inhibition of apoptosis by ghrelin were eliminated on pretreatment with compound C, an AMP-activated protein kinase (AMPK) inhibitor. Furthermore, inhibition of Ca2+/Calmodulin-dependent protein kinase kinase (CaMKK), an upstream kinase of AMPK, made ghrelin fail to activate AMPK and simultaneously reversed ghrelin’s promotion of autophagy. In conclusion, ghrelin could exert its cardioprotective effects on cardiac hypertrophy by promoting autophagy, possibly via CaMKK/AMPK signaling pathway.

Glucagon-Like Peptide-1 Analog Liraglutide Attenuates Pressure-Overload Induced Cardiac Hypertrophy and Apoptosis through Activating ATP Sensitive Potassium Channels.

This study aimed to investigate whether inhibition of glucagon-like peptide-1 (GLP-1) on pressure overload induced cardiac hypertrophy and apoptosis is related to activation of ATP sensitive potassium (KATP) channels. Male SD rats were randomly divided into five groups: sham, control (abdominal aortic constriction), GLP-1 analog liraglutide (0.3mg/kg/twice day), KATP channel blocker glibenclamide (5mg/kg/day), and liraglutide plus glibenclamide. Relative to the control on week 16, liraglutide upregulated protein and mRNA levels of KATP channel subunits Kir6.2/SUR2 and their expression in the myocardium, vascular smooth muscle, aortic endothelium, and cardiac microvasculature. Consistent with a reduction in aortic wall thickness (61.4 ± 7.6 vs. 75.0 ± 7.6μm, p < 0.05), liraglutide enhanced maximal aortic endothelium-dependent relaxation in response to acetylcholine (71.9 ± 8.7 vs. 38.6 ± 4.8%, p < 0.05). Along with a reduction in heart to body weight ratio (2.6 ± 0.1 vs. 3.4 ± 0.4, mg/g, p < 0.05) by liraglutide, hypertrophied cardiomyocytes (371.0 ± 34.4 vs. 933.6 ± 156.6μm2, p < 0.05) and apoptotic cells (17.5 ± 8.2 vs. 44.7 ± 7.9%, p < 0.05) were reduced. Expression of anti-apoptotic protein BCL-2 and contents of myocardial ATP were augmented, and expression of cleaved-caspase 3 and levels of serum Tn-I/-T were reduced. Echocardiography and hemodynamic measurement showed that cardiac systolic function was enhanced as evidenced by increased ejection fraction (88.4 ± 4.8 vs. 73.8 ± 5.1%, p < 0.05) and left ventricular systolic pressure (105.2 ± 10.8 vs. 82.7 ± 7.9mmHg, p < 0.05), and diastolic function was preserved as shown by a reduction of ventricular end-diastolic pressure (-3.1 ± 2.9 vs. 6.7 ± 2.8mmHg, p < 0.05). Furthermore, left ventricular internal diameter at end-diastole (5.8 ± 0.5 vs. 7.7 ± 0.6mm, p < 0.05) and left ventricular internal diameter at end-systole (3.0 ± 0.6 vs. 4.7 ± 0.4mm, p < 0.05) were improved. Dietary administration of glibenclamide alone did not alter all the parameters measured but significantly blocked liraglutide-exerted cardioprotection. Liraglutide ameliorates cardiac hypertrophy and apoptosis, potentially via activating KATP channel-mediated signaling pathway. These data suggest that liraglutide might be considered as an adjuvant therapy to treat patients with heart failure.

Effect of Irisin on Pressure Overload–Induced Cardiac Remodeling

Irisin has been considered a prognostic factor in several cardiovascular diseases. Nevertheless, no data are available on the role of irisin in cardiac remodeling. This study aimed to determine the potential role of irisin in cardiac remodeling and explore potential mechanisms. A total of 40 rats that underwent transverse abdominal aortic constriction (TAC) surgery or sham operation were divided into four groups: sham+saline (NS), sham+irisin, TAC+NS, and TAC+irisin. After 6weeks of treatment, echocardiography was performed to assess invivo cardiac morphology. The left ventricular myocardium was prepared and observed by pathological examination. The effect of irisin on cardiomyocyte apoptosis and the expression of oxidative stress and cardiac hypertrophy markers were observed. Then, the effect of irisin on the Akt signaling system was also detected. The rats in the TAC group displayed obvious signs of cardiac dysfunction and cardiac hypertrophy, and irisin treatment could reverse these changes. Irisin could inhibit the expression of nicotinamide adenine dinucleotide phosphate oxidase 2 and xanthine oxidase in TAC rats and increase the expression of antioxidant enzymes. Furthermore, the expression of phosphorylated protein kinase B (p-Akt), phosphorylated mammalian target of rapamycin (p-mTOR), and phosphorylated glycogen synthase kinase 3β (p-GSK3β) was much higher in the cardiac remodeling groups (p <0.05 vs. sham rats). Irisin could relieve the inhibition effect and reduce the expression level of these three proteins. Irisin treatment could significantly improve cardiac remodeling by inhibiting oxidative stress via attenuating the Akt signaling activation.

Activation of M3AChR (Type 3 Muscarinic Acetylcholine Receptor) and Nrf2 (Nuclear Factor Erythroid 2-Related Factor 2) Signaling by Choline Alleviates Vascular Smooth Muscle Cell Phenotypic Switching and Vascular Remodeling.

Phenotypic switching of vascular smooth muscle cells (VSMCs) plays a critical role in atherosclerosis, vascular restenosis, and hypertension. Choline exerts cardioprotective effects; however, little is known about its effects on VSMC phenotypic switching and vascular remodeling. Here, we investigated whether choline modulates VSMC phenotypic changes and explored the underlying mechanisms. Approach and Results: In cultured VSMCs, choline promoted Nrf2 (nuclear factor erythroid 2-related factor 2) nuclear translocation, inducing the expression of HO-1 (heme oxygenase-1) and NQO-1 (NAD[P]H quinone oxidoreductase-1). Consequently, choline ameliorated Ang II (angiotensin II)-induced increases in NOX (NAD[P]H oxidase) expression and the mitochondrial reactive oxygen species level, thereby attenuating Ang II-induced VSMC phenotypic switching, proliferation, and migration, presumably via M3AChRs (type 3 muscarinic acetylcholine receptors). Downregulation of M3AChR or Nrf2 diminished choline-mediated upregulation of Nrf2, HO-1, and NQO-1 expression, as well as inhibition of VSMC phenotypic transformation, suggesting that M3AChR and Nrf2 activation are responsible for the protective effects of choline. Moreover, activation of the Nrf2 pathway by sulforaphane suppressed Ang II-induced VSMC phenotypic switching and proliferation, indicating that Nrf2 is a key regulator of VSMC phenotypic switching and vascular homeostasis. In a rat model of abdominal aortic constriction in vivo, choline attenuated VSMC phenotypic transformation and vascular remodeling in a manner related to activation of the Nrf2 pathway. These results reveal that choline impedes VSMC phenotypic switching, proliferation, migration, and vascular remodeling by activating M3AChR and Nrf2-antioxidant signaling and suggest a novel role for Nrf2 in VSMC phenotypic modulation.

Hydrogen-rich saline mitigates pressure overload-induced cardiac hypertrophy and atrial fibrillation in rats via the JAK-STAT signalling pathway.

ObjectiveTo investigate if hydrogen-rich saline (HRS), which has been shown to have antioxidant and anti-inflammatory properties, could mitigate cardiac remodelling and reduce the incidence of atrial fibrillation (AF) in the rat model of cardiac hypertrophy.MethodsPressure overload was induced in rats by abdominal aortic constriction (AAC). The animals were separated into four groups: sham; AAC group; AAC plus low dose HRS (LHRS); AAC plus high dose HRS (HHRS). The sham and AAC groups received normal saline intraperitoneally and the LHRS and HHRS groups received 3 or 6 ml/kg HRS daily for six weeks, respectively. In vitro research was also performed using cardiotrophin-1 (CT-1)-induced hypertrophy of cultured neonatal rat cardiomyocytes.ResultsCardiac hypertrophy was successfully induced by AAC and low and high dose HRS mitigated the pressure overload as shown by lower heart and atrial weights in these treatment groups. AF incidence and duration of the HRS groups were also significantly lower in the HRS groups compared with the AAC group. Atrial fibrosis was also reduced in the HRS groups and the JAK-STAT signalling pathway was down-regulated. In vitro experiments showed that hydrogen-rich medium mitigated the CT-1-induced cardiomyocyte hypertrophy with a similar effect as the JAK specific antagonists AG490.ConclusionsHRS was found to mitigate cardiac hypertrophy induced by pressure overload in rats and reduce atrial fibrosis and AF which was possibly achieved via inhibition of the JAK-STAT signalling pathway.

Exogenous supplement of glucagon like peptide-1 protects the heart against aortic banding induced myocardial fibrosis and dysfunction through inhibiting mTOR/p70S6K signaling and promoting autophagy

Mammalian target of rapamycin (mTOR) and a ribosomal protein S6 kinase (p70S6K) mediate tissue fibrosis and negatively regulate autophagy. This study aims to investigate whether glucagon-like peptide-1 (GLP-1) analog liraglutide protects the heart against aortic banding-induced cardiac fibrosis and dysfunction through inhibiting mTOR/p70S6K signaling and promoting autophagy activity. Male SD rats were randomly divided into four groups (n=6/each group): sham operated control; abdominal aortic constriction (AAC); liraglutide treatment during AAC (0.3mg/kg, injected subcutaneously twice daily); rapamycin treatment during AAC (0.2mg/kg/day, administered by gastric gavage). Relative to the animals with AAC on week 16, liraglutide treatment significantly reduced heart/body weight ratio, inhibited cardiomyocyte hypertrophy, and augmented plasma GLP-1 level and tissue GLP-1 receptor expression. Phosphorylation of mTOR/p70S6K, populations of myofibroblasts and synthesis of collagen I/III in the myocardium were simultaneously inhibited. Furthermore, autophagy regulating proteins: LC3-II/LC3-I ratio and Beclin-1 were upregulated, and p62 was downregulated by liraglutide. Compared with liraglutide group, treatment with rapamycin, a specific inhibitor of mTOR, compatibly augmented GLP-1 receptor level, inhibited phosphorylation of mTOR/p70S6K and expression of p62 as well as increased level of LC3-II/LC3-I ratio and Beclin-1, suggesting that there is an interaction between GLP-1 and mTOR/p70S6K signaling in the regulation of autophagy. In line with these modifications, treatment with liraglutide and rapamycin significantly reduced perivascular/interstitial fibrosis, and preserved systolic/diastolic function. These results suggest that the inhibitory effects of liraglutide on cardiac fibrosis and dysfunction are potentially mediated by inhibiting mTOR/p70S6K signaling and enhancing autophagy activity.

Overexpression of FNTB and the activation of Ras induce hypertrophy and promote apoptosis and autophagic cell death in cardiomyocytes.

Farnesyltransferase (FTase) is an important enzyme that catalyses the modification of protein isoprene downstream of the mevalonate pathway. Previous studies have shown that the tissue of the heart in the suprarenal abdominal aortic coarctation (AAC) group showed overexpression of FTaseβ (FNTB) and the activation of the downstream protein Ras was enhanced. FTase inhibitor (FTI) can alleviate myocardial fibrosis and partly improve cardiac remodelling in spontaneously hypertensive rats. However, the exact role and mechanism of FTase in myocardial hypertrophy and remodelling are not fully understood. Here, we used recombinant adenovirus to transfect neonatal rat ventricular cardiomyocytes to study the effect of FNTB overexpression on myocardial remodelling and explore potential mechanisms. The results showed that overexpression of FNTB induces neonatal rat ventricular myocyte hypertrophy and reduces the survival rate of cardiomyocytes. FNTB overexpression induced a decrease in mitochondrial membrane potential and increased apoptosis in cardiomyocytes. FNTB overexpression also promotes autophagosome formation and the accumulation of autophagy substrate protein, LC3II. Transmission electron microscopy (TEM) and mCherry‐GFP tandem fluorescent‐tagged LC3 (tfLC3) showed that FNTB overexpression can activate autophagy flux by enhancing autophagosome conversion to autophagolysosome. Overactivated autophagy flux can be blocked by bafilomycin A1. In addition, salirasib (a Ras farnesylcysteine mimetic) can alleviate the hypertrophic phenotype of cardiomyocytes and inhibit the up‐regulation of apoptosis and autophagy flux induced by FNTB overexpression. These results suggest that FTase may have a potential role in future treatment strategies to limit the adverse consequences of cardiac hypertrophy, cardiac dysfunction and heart failure.

Puerarin ameliorated pressure overload-induced cardiac hypertrophy in ovariectomized rats through activation of the PPARα/PGC-1 pathway.

Estrogen deficiency induces cardiac dysfunction and increases the risk of cardiovascular disease in postmenopausal women and in those who underwent bilateral oophorectomy. Previous evidence suggests that puerarin, a phytoestrogen, exerts beneficial effects on cardiac function in patients with cardiac hypertrophy. In this study, we investigated whether puerarin couldprevent cardiac hypertrophy and remodeling in ovariectomized, aortic-banded rats. Female SD rats subjected to bilateral ovariectomy (OVX) plus abdominal aortic constriction (AAC). The rats were treated withpuerarin (50 mg·kg-1 ·d-1, ip) for 8 weeks. Then echocardiography was assessed, and the rats were sacrificed, their heart tissues were extracted and allocated for further experiments. We showed that puerarinadministration significantly attenuated cardiac hypertrophy and remodeling in AAC-treated OVX rats, which could be attributed to activation of PPARα/PPARγ coactivator-1 (PGC-1) pathway. Puerarinadministration significantly increased the expression of estrogen-related receptor α, nuclear respiratory factor 1, and mitochondrial transcription factor A in hearts.Moreover, puerarinadministrationregulated the expression of metabolic genes in AAC-treated OVX rats. Hypertrophic changes could be inducedin neonatal rat cardiomyocytes (NRCM) in vitro by treatment with angiotensin II (Ang II, 1 μM), which was attenuated by co-treatemnt withpuerarin (100 μM). We further showed that puerarin decreased Ang II-induced accumulation of non-esterified fatty acids (NEFAs) and deletion of ATP, attenuated the Ang II-induced dissipation of the mitochondrial membrane potential, and improved the mitochondrial dysfunction in NRCM. Furthermore, addition of PPARα antagonist GW6471 (10 μM) partially abolished the anti-hypertrophic effects and metabolic effects of puerarinin NRCM. In conclusion,puerarin prevents cardiac hypertrophy in AAC-treated OVX rats through activation of PPARα/PGC-1 pathway and regulation of energy metabolism remodeling. This may provide a new approach to prevent the development of heart failure in postmenopausal women.