Administration Of Isoproterenol Research Articles

AKAP12 Upregulation Associates With PDE8A to Accelerate Cardiac Dysfunction.

In heart failure, signaling downstream the β2-adrenergic receptor is critical. Sympathetic stimulation of β2-adrenergic receptor alters cAMP (cyclic adenosine 3',5'-monophosphate) and triggers PKA (protein kinase A)-dependent phosphorylation of proteins that regulate cardiac function. cAMP levels are regulated in part by PDEs (phosphodiesterases). Several AKAPs (A kinase anchoring proteins) regulate cardiac function and are proposed as targets for precise pharmacology. AKAP12 is expressed in the heart and has been reported to directly bind β2-adrenergic receptor, PKA, and PDE4D. However, its roles in cardiac function are unclear. cAMP accumulation in real time downstream of the β2-adrenergic receptor was detected for 60 minutes in live cells using the luciferase-based biosensor (GloSensor) in AC16 human-derived cardiomyocyte cell lines overexpressing AKAP12 versus controls. Cardiomyocyte intracellular calcium and contractility were studied in adult primary cardiomyocytes from male and female mice overexpressing cardiac AKAP12 (AKAP12OX) and wild-type littermates post acute treatment with 100-nM isoproterenol (ISO). Systolic cardiac function was assessed in mice after 14 days of subcutaneous ISO administration (60 mg/kg per day). AKAP12 gene and protein expression levels were evaluated in left ventricular samples from patients with end-stage heart failure. AKAP12 upregulation significantly reduced total intracellular cAMP levels in AC16 cells through PDE8. Adult primary cardiomyocytes from AKAP12OX mice had significantly reduced contractility and impaired calcium handling in response to ISO, which was reversed in the presence of the selective PDE8 inhibitor (PF-04957325). AKAP12OX mice had deteriorated systolic cardiac function and enlarged left ventricles. Patients with end-stage heart failure had upregulated gene and protein levels of AKAP12. AKAP12 upregulation in cardiac tissue is associated with accelerated cardiac dysfunction through the AKAP12-PDE8 axis.

L-Carvone from Mentha spicata L. Leaves Suppresses Oxidative Stress and Hypertrophy in the Isoproterenol-Induced Rat Model of Cardiac Hypertrophy

The effect of L-Carvone (a natural monoterpene from Mentha spicata L., leaves) in cardiac hypertrophy caused by isoproterenol administration was investigated. Male rats (Wistar) were divided into five groups: Control, diseased, diseased rats with losartan, diseased rats with low-dose L-Carvone, and high-dose L-Carvone. Rats were injected with isoproterenol (5 mg/kg) for 30 days to induce cardiac hypertrophy. Then, simultaneously with Losartan (15 mg/kg), L-Carvone was administered orally at a dosage of 25 mg/kg (low dose) and 100 mg/kg (high dose) treatment. The cardioprotective effect of L-Carvone was evaluated by examining the heart morphometric indices, and ECG analyses. Chronic isoproterenol administration resulted in changes in morphometric indices of the heart, ECG tracings, biochemical parameters such as tissue glucose, proteins, lipid profiles, serum cardiac markers, antioxidants, and histopathological integrity of the heart tissue. When compared with the isoproterenol group, L-Carvone administrated for 30 days ameliorated all these changes in rats significantly (p < 0.05). L-Carvone adequately averted chronic cardiac hypertrophy, most probably through its antioxidant potential.

Cardioprotective Potential of <i>Albizzia lebbeck</i>: Insights Isoproterenol-Induced Myocardial Infarction in Rats

This study investigates the cardioprotective potential of Albizzia lebbeck (Shirish) ethanol leaf extract against Isoproterenol (ISO)-induced myocardial infarction in Wistar albino rats. Cardiovascular Diseases (CVDs) are a major global health concern, contributing significantly to morbidity and mortality. A. lebbeck, a medicinal plant with documented pharmacological activities, has not been scientifically studied for its cardioprotective properties. The research utilised a rat model of ISO-induced myocardial infarction, a well-established experimental approach to study preventive effects on myocardial damage. The study included the isolation and preparation of A. lebbeck ethanol leaf extract (MEAL) and its administration at different doses (200 mg/kg and 400 mg/kg) to ISO-treated rats. Various parameters, including relative organ weight, cardiac biomarkers (cTnI, LDH, CK-MB), total proteins, oxidative stress markers (SOD, MDA), and histopathological changes, were assessed. The results revealed that ISO administration induced cardiac hypertrophy, increased serum biomarkers, and oxidative stress, indicating myocardial damage. Treatment with MEAL, especially at the higher dose (400 mg/kg), significantly mitigated these effects. MEAL administration reduced the heart-to-body weight ratio, normalised serum biomarkers, restored endogenous antioxidant enzyme levels, and showed a protective effect against structural damage in histopathological examination. In conclusion, A. lebbeck ethanol leaf extract demonstrated significant cardioprotective effects against ISO-induced myocardial infarction in rats. These findings suggest the potential of A. lebbeck as a natural therapeutic agent for preventing or ameliorating cardiac damage associated with stress-induced conditions. Further research is warranted to elucidate the specific mechanisms underlying its cardioprotective properties and explore its potential clinical applications.

Multiple organs injury and myocardial energy metabolism disorders induced by isoproterenol

The study sought to assess the detrimental effects of isoproterenol (ISO) on major organs and investigate the potential reversibility of these adverse reactions in mice. Male mice were divided into normal control, 0.2 mg/kg.d and 3.0 mg/kg.d ISO groups, and were subcutaneously administered of the respective doses for 14 consecutive days. Subsequently, a recovery period experiment was conducted, replicating the aforementioned procedure, followed by an additional 2-week recovery period for the mice. Following 14 consecutive days of administration, mice treated with ISO exhibited notable cardiac damage manifested by abnormal ECG patterns, dysregulated energy metabolism, elevated cardiac hypertrophy, and increased heart pathological score. Additionally, the administration of ISO resulted in liver and kidney damage, as evidenced by increased pathological score, serum albumin level, and urea level. Lung damage was also observed, indicated by an increase in lung pathological score. Furthermore, the administration of ISO at a dosage of 3.0 mg/kg.d resulted in a decrease in liver mass index, serum iron content, and an increase in lung mass index. After a 2-week recovery period, mice treated with ISO showed abnormalities in ECG patterns and dysregulated myocardial energy metabolism, accompanied by a decrease in serum iron content. Histopathological examinations revealed continued pathological changes in the heart and lung, as well as significant hemosiderin deposition in the spleen. Furthermore, the group treated with ISO at a dosage of 3.0 mg/kg.d showed an increase in serum AST and TP levels. In summary, the study demonstrates that both 0.2 mg/kg.d and 3.0 mg/kg.d doses of ISO can induce damage to the heart, liver, lung, kidney, and spleen, with the higher dose causing more severe injuries. After a 2-week withdrawal period, the liver, kidney, and thymus injuries caused by 0.2 mg/kg ISO shows signs of recovery, while damage to the heart, lung, and spleen persists. The thymus injury mostly recovers, with minimal kidney pathology, but significant damage to the heart, liver, and lung remains even after the withdrawal period for the 3.0 mg/kg ISO dose.

Sex- and age-dependent susceptibility to ventricular arrhythmias in the rat heart ex vivo

The incidence of life-threatening ventricular arrhythmias, the most common cause of sudden cardiac death (SCD), depends largely on the arrhythmic substrate that develops in the myocardium during the aging process. There is a large deficit of comparative studies on the development of this substrate in both sexes, with a particular paucity of studies in females. To identify the substrates of arrhythmia, fibrosis, cardiomyocyte hypertrophy, mitochondrial density, oxidative stress, antioxidant defense and intracellular Ca2+ signaling in isolated cardiomyocytes were measured in the hearts of 3- and 24-month-old female and male rats. Arrhythmia susceptibility was assessed in ex vivo perfused hearts after exposure to isoproterenol (ISO) and hydrogen peroxide (H2O2). The number of ventricular premature beats (PVBs), ventricular tachycardia (VT) and ventricular fibrillation (VF) episodes, as well as intrinsic heart rate, QRS and QT duration, were measured in ECG signals recorded from the surfaces of the beating hearts. After ISO administration, VT/VFs were formed only in the hearts of males, mainly older ones. In contrast, H2O2 led to VT/VF formation in the hearts of rats of both sexes but much more frequently in older males. We identified several components of the arrhythmia substrate that develop in the myocardium during the aging process, including high spontaneous ryanodine receptor activity in cardiomyocytes, fibrosis of varying severity in different layers of the myocardium (nonheterogenic fibrosis), and high levels of oxidative stress as measured by nitrated tyrosine levels. All of these elements appeared at a much greater intensity in male individuals during the aging process. On the other hand, in aging females, antioxidant defense at the level of H2O2 detoxification, measured as glutathione peroxidase expression, was weaker than that in males of the same age. We showed that sex has a significant effect on the development of an arrhythmic substrate during aging. This substrate determines the incidence of life-threatening ventricular arrhythmias in the presence of additional stimuli with proarrhythmic potential, such as catecholamine stimulation or oxidative stress, which are constant elements in the pathomechanism of most cardiovascular diseases.

Cardioprotective effects of Callicarpa tomentosa leaf extract in Wistar albino rats against isoproterenol-induced myocardial necrosis: Phytochemical analysis and in vitro antioxidant study

BackgroundGlobally, cardiovascular disease (CVD) remains the foremost cause of mortality. Conventional medications are associated with several complications, necessitating an alternative, safe and efficacious medicine. Therefore, the study was planned to assess the cardioprotective efficacy of Callicarpa tomentosa (CT) leaf extract against isoproterenol (ISO)-induced myocardial failure in experimental rats. Materials and methodsCT leaf extract was subjected to phytochemical analysis, total phenolic and flavonoid content measurement, and in vitro antioxidant evaluation. Additionally, the protection from myocardial injury was evaluated based on the estimation of biomarkers including CK-MB, CKNAC, and LDH in both the low-dose (200 mg/kg) and high-dose (400 mg/kg) groups of rats. We measured endogenous antioxidants in heart tissue to estimate the antioxidant potential. Histopathological analysis confirmed the biochemical results. ResultsThe findings of this study indicated that the CT leaf extract contained several phytoconstituents such as alkaloids, flavonoids, steroids and triterpenoids, cardiac glycosides, carbohydrates, phenols, saponins, and tannins. The CT's total phenol content was 33.3 ± 0.14 mg GAE (Gallic Acid Equivalent) per gram of extract, while its total flavonoid concentration was 76.5 ± 1.2 mg QUE (Quercetin Equivalent). In the DPPH assay, CT had a mean inhibitory effect of 60.06 ± 1.358 g/ml, whereas its IC50 in the H2O2 radical scavenging activity assay was 102.85 ± 0.194 g/ml. The electrocardiograms of the treated animals demonstrated considerable recovery from ISO-induced electrophysiological abnormalities as well and the amount of endogenous biomarkers was significantly reduced in animals that receivedCT treatment. Additionally, the use of CT reversed the effects of ISO administration on SOD activity, increased GSH levels, and lowered LPO levels. The damage to the heart tissues was significantly reduced, with the tissue architecture appearing closer to normal in groups that received high doses of CT. ConclusionThese results suggest that C. tomentosa leaf extract has potent antioxidant activity and provides protection against isoproterenol-induced cardiac necrosis in Wistar albino rats. The cardioprotectivebenefits are attributed to the presence of active components in the extract, which aid in the restoration of antioxidant equilibrium and the reduction of damage caused by oxidative stress.

Pomegranate fruit peel extract improves cardiac functions via suppressing oxidative stress, fibrosis, and myocardial infarction in Long-Evans rats

The pomegranate fruit (locally known as Dalim) is a rich source of various bioactive metabolites. The cardioprotective effect was aimed to investigate on polyphenol-rich pomegranate peel extract (PPE) that were administered isoproterenol, a synthetic catecholamine used to induce cardiac stress in rats. Twenty four adult rats were taken to evaluate the effects. The selected rats were divided into four groups, serving as the control (Group I), Isoproterenol (ISO) administered (Group II), PPE with ISO treatment (Group III) and gallic acid (polyphenol) along with ISO administration (Group IV). ISO administration increased inflammatory cell infiltration, fibrosis and lipid peroxidation. However, antioxidant enzyme activities were reduced in heart tissues by using isoproterenol. The findings of the study indicate that the various detrimental effects arose on the rat’s heart tissues by ISO administration which seemed to be protected by the administration of the polyphenol-rich PPE. This protection was associated with several positive outcomes, including: reduced inflammatory cell infiltration and fibrosis, reduction in free radicals by improving antioxidant enzymes activities (SOD, catalase), suppression of oxidative stress markers (MDA, NO, APOP), and reduction in inflammatory marker (MPO). Besides, PPE treatment normalized the elevated ALT, AST, ALP, and CK-MB levels. The cardioprotective effects shown by PPE may be due to the presence of polyphenolic compounds, as determined by HPLC analysis. Overall, the outcomes recommend that polyphenol enriched PPE may protect cardiac tissues in ISO-administered rats by suppressing oxidative stress, fibrosis, and myocardial infarction as well as enhancing antioxidant enzyme functions.

Rat Model of Isoproterenol-Induced Myocardial Injury.

Isoproterenol (ISO) administration produces significant biochemical and histological changes including oxidative stress, reactive oxygen species (ROS) overproduction, and inflammation that leads to aggravation of myocardial injury. Subcutaneous or intraperitoneal ISO injection into rats can replicate several features of human heart disease, making it a useful tool for comprehending the underlying mechanisms and evaluating potential therapeutic strategies. In the present chapter, we elaborate on how depending on the precise experimental goals and the intended level of severity, different dosages and regimens are employed to induce myocardial injury.

Treatment with β-Adrenoceptor Agonist Isoproterenol Reduces Non-parenchymal Cell Responses in LPS/D-GalN-Induced Liver Injury

There is an increasing evidence indicating the involvement of the sympathetic nervous system (SNS) in liver disease development. To achieve an extensive comprehension of the obscure process by which the SNS alleviates inflammatory damage in non-parenchymal liver cells (NPCs) during acute liver failure (ALF), we employ isoproterenol (ISO), a beta-adrenoceptor agonist, to mimic SNS signaling. ISO was administered to C57BL/6J mice to establish an acute liver failure (ALF) model using LPS/D-GalN, which was defined as ISO + ALF. Non-parenchymal cells (NPCs) were isolated from liver tissues and digested for tandem mass tag (TMT) labeled proteomics to identify differentially expressed proteins (DEPs). The administration of ISO resulted in a decreased serum levels of pro-inflammatory cytokines, e.g., TNF-α, IL-1β, and IL-6 in ALF mice, which alleviated liver damage. By using TMT analysis, it was possible to identify 1587 differentially expressed proteins (DEPs) in isolated NPCs. Notably, over 60% of the DEPs in the ISO + ALF vs. ALF comparison were shared in the Con vs. ALF comparison. According to enrichment analysis, the DEPs influenced by ISO in ALF mice were linked to biological functions of heme and fatty acid metabolism, interferon gamma response, TNFA signaling pathway, and mitochondrial oxidation function. Protein-protein interaction network analysis indicated Mapk14 and Caspase3 may serve as potentially valuable indicators of ISO intervention. In addition, the markers on activated macrophages, such as Mapk14, Casp1, Casp8, and Mrc1, were identified downregulated after ISO initiation. ISO treatment increased the abundance of anti-inflammatory markers in mouse macrophages, as evidenced by the immunohistochemistry (IHC) slides showing an increase in Arg + staining and a reduction in iNOS + staining. Furthermore, pretreatment with ISO also resulted in a reduction of LPS-stimulated inflammation signaling markers, Mapk14 and NF-κB, in human THP-1 cells. Prior treatment with ISO may have the potential to modify the biological functions of NPCs and could serve as an innovative pharmacotherapy for delaying the pathogenesis and progression of ALF.

Transcriptional changes during isoproterenol-induced cardiac fibrosis in mice.

Introduction: β-adrenergic stimulation using β-agonists such as isoproterenol has been routinely used to induce cardiac fibrosis in experimental animal models. Although transcriptome changes in surgical models of cardiac fibrosis such as transverse aortic constriction (TAC) and coronary artery ligation (CAL) are well-studied, transcriptional changes during isoproterenol-induced cardiac fibrosis are not well-explored. Methods: Cardiac fibrosis was induced in male C57BL6 mice by administration of isoproterenol for 4, 8, or 11days at 50mg/kg/day dose. Temporal changes in gene expression were studied by RNA sequencing. Results and discussion: We observed a significant alteration in the transcriptome profile across the different experimental groups compared to the saline group. Isoproterenol treatment caused upregulation of genes associated with ECM organization, cell-cell contact, three-dimensional structure, and cell growth, while genes associated with fatty acid oxidation, sarcoplasmic reticulum calcium ion transport, and cardiac muscle contraction are downregulated. A number of known long non-coding RNAs (lncRNAs) and putative novel lncRNAs exhibited differential regulation. In conclusion, our study shows that isoproterenol administration leads to the dysregulation of genes relevant to ECM deposition and cardiac contraction, and serves as an excellent alternate model to the surgical models of heart failure.

Lactobacillus plantarum Enhanced the Cardioprotective Efficacy of Arctiin in Isoproterenol Cardiac Injury in BALB/c Mice

Background Isoproterenol is a drug used for the treatment of bradycardia that has many side effects due to its non-selective β-adrenoceptor agonist properties. Aim In this study, we evaluated an in vivo experimental model for isoproterenol (ISO) cardiac injury using BALB/c mice and protective treatment with a combined optimized dose of Arctiin (AR) and Lactobacillus plantarum (LP) (ARLP; 30 mg/kg b.w. AR and viable 106 CFU/mL LP p.o.) together. Introduction Isoproterenol causes cardiac injury in many instances. Arctiin is a naturally occurring lignin glycoside present in many herbal medicinal plants that has many beneficial effects for humans. Lactobacillus plantarum is yet another beneficial probiotic that benefits largely to humans. Materials and Methods Male BALB/c mice in appropriate groups (6 animals each) were treated with ARLP for 7 days with ISO administration (100 mg/kg i.p.) on days 5 and 6. On the 8th day, animals were sacrificed. Serum and heart samples were collected for further processing. CK-MB, cardiac troponin, AST, ALT, LDH, GST, GPx, CAT, SOD, GSH, GSSG, MDA, nuclear factor kappa B (NFκB), TNF-α, and IL-6 by ELISA and gene expressions of nuclear factor erythroid 2-related factor 2 (Nrf2) were estimated in samples. Results Mice administered with ISO showed a prominent rise in the serum marker enzyme activities and tissue oxidative stress markers (MDA and GSSG). Furthermore, marked reductions in body weight and enzymatic and non-enzymatic antioxidant levels were noticed in ISO toxicity. Alterations in proinflammatory cytokines (TNF-α and IL-6) and Nrf2 levels by RT-PCR were analyzed. Histopathology of the heart also indicated cardiac injury in ISO-intoxicated mice. ARLP pretreatment prevented all these cardiac injuries and exerted significant ( p ≤ 0.05) prophylactic protection toward cardiac tissue. Further, we analyzed the possible interactions between AR and LP in vitro, to understand the influence of ARonLP, which showed no significant suppressive/antibacterial activity on LP. Conclusion In conclusion, ARLP exerts a strong cardioprotective and anti-inflammatory activity in cardiovascular injury.

Dietary Theobroma cocao Prevents Hepatotoxicity Secondary to Myocardial Injury

Dietary products like cocoa with high flavonoids may play a role to boost the integrity of the liver against insults resulting from myocardial injury. Twenty-four male Wistar rats, divided into four groups of 6 rats were used for the study. Group 1 was control and received 0.9% normal saline via oral gavage. Group 2 was the acute myocardial injury group, and received two doses of subcutaneous injection of isoproterenol (100 mg/kg body weight) at an interval of 24 hours between doses. Group 3 was administered Theobroma cacao (100 mg/kg body weight orally) only for 2 weeks. Group 4 was pretreated with Theobroma cacao for 2 weeks and then followed by injection of isoproterenol (100 mg/kg body weight) on day 15 and 16. At the end of the experimental period, the rats were euthanized and serum collected for laboratory investigations of lactate dehydrogenase, troponin, alanine aminotransferase, aspartate transaminase, and alkaline phosphatase. Administration of isoproterenol resulted in a significant (p<0.001) elevation in the serum concentrations of the cardiac biomarkers, troponins and LDH when compared with the control group. Pretreatment with Theobroma cacao before myocardial infarction caused a significant (p<0.01) reduction in the concentrations of LDH and troponins with values similar to the control group. The serum liver enzymes AST, ALT, and ALP levels were also significantly (p<0.01) but were reversed in the Theobroma cacao cocoa treatment groups. It is concluded that Theobroma cacao prevents hepatic and heart damage thus providing a support for the prophylactic use of dietary Theobroma cacao against hepatotoxicity.

Efficacy of Low-Dose Isoproterenol Infusion for the Exclusion of a Left Atrial Appendage Thrombus in Patients With Dense Spontaneous Echo Contrast Caused by Atrial Fibrillation.

In patients with atrial fibrillation (AF) and severe blood stasis in the left atrial appendage (LAA), dense spontaneous echo contrast (SEC) disturbs the distinct visualization of the LAA interior, thus making thrombus diagnosis inconclusive. We aimed to prospectively assess the efficacy and safety of a protocol for a low-dose isoproterenol (ISP) infusion to reduce SEC to exclude an LAA thrombus.Methods and Results: We enrolled 17 patients with AF and dense SEC (Grade 4 or sludge). ISP was infused with gradually increasing doses of 0.01, 0.02, and 0.03 μg/kg/min at 3-min intervals. After increasing the dose to 0.03 μg/kg/min for 3 min, or when the LAA interior was visible, the infusion was terminated. We reassessed the SEC grade, presence of an LAA thrombus, LAA function, and left ventricular ejection fraction (LVEF) within 1 min of ISP termination. Compared with baseline, ISP significantly increased LAA flow velocity, the LAA emptying fraction, LAA wall velocities, and LVEF (all P<0.01). ISP administration significantly reduced the SEC grade (median) from 4 to 1 (P<0.001). The SEC grade decreased to ≤2 in 15 (88%) patients, and the LAA thrombus was excluded. There were no adverse events. Low-dose ISP infusion may be effective and safe to reduce SEC and exclude an LAA thrombus by improving LAA function and LVEF.

Cardioprotective effect of tetra(aniline) containing terpolymers through miR-15a-5p and MFN-2 regulation against hypertrophic responses

ObjectiveCardiac hypertrophy is a condition of abnormal cardiomyocyte enlargement accompanied by ventricular wall thickening. The study aims to investigate the role of miR-15a-5p in the regulation of mitofusin-2 (MFN-2) and to explore the cardioprotective effect of terpolymers ES-37 and L-37. MethodsIn this study, the Sprague Dawley rats’ cardiac hypertrophic model was established by administering 5 mg/kg Isoproterenol subcutaneously every other day for 14 days. As treatment rats received NAC (50 mg/kg), NAC treatment (50 mg/kg NAC + 5 mg/kg ISO), ES-37 (1 mg/kg) and ES-37 treatment (1 mg/kg ES-37+5 mg/kg ISO), L-37 (1 mg/kg) and L-37 treatment (1 mg/kg L-37+5 mg/kg ISO). subcutaneously every other day for 14 days. NAC, ES 37 and L-37 were given after 1 h of Isoproterenol administration in treatment groups. Cardiac hypertrophy was confirmed through morphological and histological analysis. For estimation of oxidative stress profiling, ROS and TBARS and antioxidative profiling superoxide dismutase (SOD), Catalase, and Glutathione (GSH) levels were checked. Triglyceride, cholesterol, alanine transaminase (ALT), and aspartate transaminase (AST) were performed to evaluate levels of lipid profiling and liver profiling. Molecular expression analysis was checked through real-time PCR, and western blotting both at the transcriptional and translational levels. Molecular docking studies were performed to study the interactions and modes of binding between the synthetic polymers with three proteins (Mitofusin-2, DRP-1 and PUMA). All the studies were carried out using the AutoDock Vina software and the protein-ligand complexes were visualized in Biovia Discovery Studio.Cardiac hypertrophy was confirmed by the relative changes in the cellular structure of the heart by histopathological examination and physiological changes by estimating organ weights. Biochemical profiling results depict elevated oxidative and lipid profiles signify myocardial damage. N-acetyl cysteine (NAC), ES-37, and L-37 overcome the cardiac hypertrophic responses through attenuating oxidative stress and enhancing the antioxidative signaling mechanism. miR-15a-5p was identified as hypertrophic microRNA directly regulating the expression of Mitofusin-2 (MFN-2). Significantly increased expression of miR-15a-5p, Dynamin related protein 1 (Drp1), and P53 upregulated modulator of apoptosis (PUMA), was observed in the disease group, whereas MFN-2 expression was observed downregulated. N-acetyl cysteine (NAC), ES-37, and L-37 showed increased expression of antiapoptotic maker MFN-2 and decreased expression of miR-15a-5p, Drp1, and PUMA in treatment groups suggesting their cardioprotective role in attenuation of cardiac hypertrophy. An analysis of the docking results shows that ES-37 has greater binding affinity with the target proteins compared to L-37, with the highest binding values reported for MFN-2. ConclusionThe physiochemical properties of ES-37 and L-37 predicted it as a good drug-like molecule and its mechanism of action is predictably through inhibition of ROS. Molecular docking results shows that the polymer ES-37 has greater binding affinity with the target proteins compared to L-37, with the highest binding values reported for MFN-2. Thus, the study validates the role and targeting of miR-15a-5p and MFN-2 in cardiac hypertrophy as well as the therapeutic potential of NAC, ES-37, and L-37 in overcoming oxidative stress and myocardial damage.

In an experimental myocardial infarction model, L-arginine pre-intervention may exert cardioprotective effects by regulating OTULIN levels and mitochondrial dynamics.

The experimental myocardial infarction (MI) model originating from isoproterenol (ISO) is frequently preferred in research due to its similarity to MI-induced damage in humans. Beneficial effects of L-arginine (L-Arg), a semi-essential amino acid, in cardiovascular diseases have been shown in many studies. This study was carried out to determine whether L-Arg pre-intervention has protective effects on heart tissue in the experimental MI model. The 28 rats used in the study were randomly divided into 4 equal groups: control, L-Arg, ISO, and L-Arg+ISO. Upon completion of all applications, cardiac markers in serum and biochemical, histopathological, and immunohistochemical examinations in cardiac tissues were performed. Cardiac markers, histopathological changes, oxidative stress, inflammation, and apoptosis were increased in the experimental MI model. In addition, administration of ISO deregulated OTULIN levels and mitochondrial dynamics in heart tissue. However, L-Arg pre-intervention showed a significant protective effect against changes in ISO-induced MI. L-Arg supplementation with cardioprotective effect may reduce the risks of possible pathophysiological processes in MI.

Ferroptosis contributes to catecholamine-induced cardiotoxicity and pathological remodeling

High levels of circulating catecholamines cause cardiac injury, pathological remodeling, and heart failure, but the underlying mechanisms remain elusive. Here we provide both in vitro and in vivo evidence that excessive β-adrenergic stimulation induces ferroptosis in cardiomyocytes, revealing a novel mechanism for catecholamine-induced cardiotoxicity and remodeling. We found that isoproterenol, a synthetic catecholamine, promoted glutathione depletion and glutathione peroxidase 4 (GPX4) degradation in cardiomyocytes, leading to GPX4 inactivation and enhanced lipid peroxidation. Isoproterenol also promoted heme oxygenase 1 (HO-1) expression by downregulating the transcription suppressor BTB and CNC homology 1 (Bach1), leading to increased labile iron accumulation through heme degradation. Moreover, isoproterenol markedly induced the accumulation of free iron and lipid reactive oxygen species (ROS) in the mitochondria, while targeted inhibition of iron overload and ROS accumulation within mitochondria effectively inhibited ferroptosis in cardiomyocytes. Importantly, isoproterenol administration markedly induced ferroptosis in the myocardium in vivo, associated with elevated non-heme iron accumulation driven by HO-1 upregulation. Strikingly, blockade of ferroptosis with ferrostatin-1 or inhibition of HO-1 activity with zinc protoporphyrin (ZnPP) effectively alleviated cardiac necrosis, pathological remodeling, and heart failure induced by isoproterenol administration. Taken together, our results reveal that catecholamine stimulation primarily induces ferroptotic cell death in cardiomyocyte through GPX4 and Bach1-HO-1 dependent signaling pathways. Targeting ferroptosis may represent a novel therapeutic strategy for catecholamine overload-induced myocardial injury and heart failure.

Cytoskeletal disarray increases arrhythmogenic vulnerability during sympathetic stimulation in a model of hypertrophic cardiomyopathy

Familial hypertrophic cardiomyopathy (FHC) patients are advised to avoid strenuous exercise due to increased risk of arrhythmias. Mice expressing the human FHC-causing mutation R403Q in the myosin heavy chain gene (MYH6) recapitulate the human phenotype, including cytoskeletal disarray and increased arrhythmia susceptibility. Following in vivo administration of isoproterenol, mutant mice exhibited tachyarrhythmias, poor recovery and fatigue. Arrhythmias were attenuated with the β-blocker atenolol and protein kinase A inhibitor PKI. Mutant cardiac myocytes had significantly prolonged action potentials and triggered automaticity due to reduced repolarization reserve and connexin 43 expression. Isoproterenol shortened cycle length, and escalated electrical instability. Surprisingly isoproterenol did not increase CaV1.2 current. We found alterations in CaV1.2-β1 adrenergic receptor colocalization assessed using super-resolution nanoscopy, and increased CaV1.2 phosphorylation in mutant hearts. Our results reveal for the first time that altered ion channel expression, co-localization and β-adrenergic receptor signaling associated with myocyte disarray contribute to electrical instability in the R403Q mutant heart.

CARDIOPROTECTIVE EFFECT OF TERIFLUNOMIDE IN AN EXPERIMENTAL MODEL OF MYOCARDIAL INFARCTION

Objective: MI is a major cause of mortality worldwide. Inflammation plays a key role in the pathology of MI. Teriflunomide (TERI), an orally active Dihydroorotate Dehydrogenase inhibitor, inhibits de novo pyrimidine synthesis. It decreases production of inflammatory cytokines and suppresses the activity and proliferation of activated lymphocytes. Hypothesis: TERI, on account of its potent anti-inflammatory activity may attenuate Isoproterenol induced cardiac injury in rats. Thus, we aimed to investigate the cardio-protective effect of Teriflunomide in isoproterenol (Iso) induced myocardial infarction. Design and method: To induce myocardial infarction in rats, we administered 2 doses of Isoproterenol (85 mg/kg/day, s.c.) on days 13th and 14th, at an interval of 24 hours. Male albino Wistar rats were divided into 5 groups (n = 6); namely normal control, isoproterenol control, Teriflunomide groups to receive saline, isoproterenol, or Teriflunomide (1, 3 or 5 mg/kg/day, p.o.) for 14 days. On the 15th day, rats were anaesthetized and right coronary artery was cannulated to record hemodynamic parameters. Blood sample was collected via cardiac puncture, heart was excised and preserved for analysis of biochemical, histopathological and ultrastructural studies. Results: Isoproterenol administration to rats resulted in induction of MI with impairment of hemodynamic parameters. Teriflunomide pretreatment showed significantly improved hemodynamic (systolic, diastolic and mean blood pressures) and cardiac function parameters (normalized ± LV dP/dt and LVEDP) with reduction in the levels of cardiac injury markers (CK-MB, LDH). Further, Teriflunomide significantly reduced oxidative stress (enhanced levels of SOD, GSH, decreased MDA levels) and inflammation (reduced levels of TNF-alpha, IL-6), led to inhibition of active JNK and p38 proteins and activation of ERK1/2, a pro-survival kinase. Furthermore, it also ameliorated apoptosis by reducing the expression of pro-apoptotic proteins (Bax and Caspase-3) and increased expression of Bcl-2, an anti-apoptotic marker. In addition, pretreatment with Teriflunomide preserved morphological and ultra-structural architecture of the myocardium as seen by H &amp; E staining and electron microscopy. Conclusions: Teriflunomide at 1 mg/kg offered cardio-protection by improving hemodynamic profile, oxidative stress profile, reduced inflammation, normalization of myocardial architecture.

4-OCTYL ITACONATE ATTENUATES ISOPROTERENOL INDUCED MYOCARDIAL DAMAGE VIA NLRP3 INFLAMMASOME PATHWAY, NRF-2/HO-1 AND MAPK PATHWAY IN AN EXPERIMENTAL MODEL

Objective: Myocardial infarction (MI) is the major cause of morbidity and mortality worldwide. According to the World Health Organisation, more than 9 million deaths occurred due to ischemic heart disease worldwide in 2016. 4-octyl itaconate (4-OI) is a cell permeable derivative of itaconate with potent anti-oxidative, anti-inflammatory and anti-fibrotic properties. Studies have shown that 4-OI inhibits pro-inflammatory cytokines (IL6, IL1beta, TNF alpha) and activates the anti-oxidant Nrf-2/HO-1 pathway. The aim of the study was to investigate the cardio-protective effect of 4-OI in experimental model of Isoproterenol induced myocardial damage. Design and method: Adult male albino wistar rats were used in the study. They were randomly divided to five groups i.e., normal control group, isoproterenol control group, 4-OI group (2.5, 5 or 10 mg/kg) for 14 days and 4-OI perse group. On the 15th day, rats were anaesthetized and right coronary artery was cannulated to record hemodynamic parameters. Following this, blood was withdrawn using cardiac puncture, heart was excised and preserved for analysis of biochemical, histopathological and molecular pathway studies. Results: Isoproterenol administration to rats resulted in induction of Myocardial damage as shown by impairment in hemodynamic parameters, left ventricular dysfunction and raised cardiac injury markers. Treatment with 4-OI significantly improved hemodynamic and cardiac injury markers (CKMB, LDH). Further, 4OI significantly reduced oxidative stress (enhanced levels of SOD, GSH, decreased MDA levels) and inflammation (reduced levels of TNF alpha, IL-6, IL-1beta and NLRP3). Further it activated the Nrf-2-HO-1 pathway while inhibits the inflammatory NFKB pathway. Apart from this, it also ameliorated apoptosis by decreasing the expression of Bax, caspase-3 and increasing the expression of anti-apoptotic Bcl-2. It also inhibited inflammatory MAPK proteins (JNK, phospho JNK, P38, phospho P38) while enhancing the expression of pro-survival kinases ERK1/2, and Phospho ERK1/ 2. Conclusions: Oral administration of 4-OI at a dose of 10 mg/kg ameliorated the severity of isoprotorenol-induced cardio-toxicity in rats via NLRP-3 inflammasome pathway, MAPK and Nrf-2/HO1 pathway and by maintaining morphological structure of heart tissue and oxidative stress profile along with reduced inflammation and apoptosis.

Cardioprotective effect of Ginger in a rat model of myocardial damage and its possible intervention in PERK-ATF4-CHOP-PUMA apoptotic pathway

For today the exact mechanisms of myocardial infarction and ischemia/reperfusion injury are still not fully understood. ER stress and integrated stress response pathways are thought to play an essential role in myocardial damage. This includes activation of endoplasmic reticulum kinase PERK, induction of activating transcription factor ATF4, expression of pro-apoptotic transcription factor CHOP and P53 up-regulated modulator of apoptosis (PUMA) involved in apoptosis control. We used a rat model of isoproterenol-induced myocardial damage to elucidate the possible cardioprotective effect of Ginger through the influence on ER stress-induced apoptotic pathway. We also compared its effect with the ACE inhibitor Captopril. Male albino Wistar rats received 1.0 or 2.0 ml of Zingiber officinale (Ginger) powder suspension (200 mg/ml) daily by intra-gastric intubation for 28 days. Isoproterenol at a dose of 85 mg/kg was IP injected on the 27th and 28th days. Serum aspartate transaminase (AST) level was measured using kinetic kit. Heart tissue was used for RNA extraction, evaluation of gene expression by Q-RT-PCR, immuno-histochemical determination of caspase-3 expression and histopathological studies. Our results showed that Isoproterenol administration increased CHOP-mRNA expression 4 folds in cardiac muscle tissue compared to normal control. Ginger pretreatment significantly decreased both CHOP and ATF4, and PUMA mRNA expression compared to Isoproterenol-treated groups. A significant reduction in ATF4 mRNA expression in a group pretreated with Captopril and Ginger compared to normal control group was observed. The results showed that Ginger reduced AST serum levels which correlated with results of histopathological studies of heart tissue. Our findings suggest that the protective effects of Ginger against myocardium damage induced by Isoproterenol may be mediated by reducing­ the endoplasmic reticulum stress by affecting the ATF4-CHOP-PUMA pathway. Keywords: AST, ATF4, Captopril, CHOP, Ginger, ischemia-reperfusion, Isoproterenol, myocardial damage, PUMA