Protective effects of 3, 4-dihydroxybenzoic acid on myocardial infarction induced by isoproterenol in rats.

Despite considerable advances in interventions and treatment, there is a high mortality rate in patients with myocardial infarction (MI). This is the first study to investigate the protective effects of 3, 4-dihydroxybenzoic acid against isoproterenol induced MI in rats. MI was induced by isoproterenol (100-mg/kg body weight) in rats. Then, rats were treated with 3, 4-dihydroxybenzoic acid (16-mg/kg body weight) for 2 weeks. Serum creatine kinase-MB, cardiac troponin-T, cardiac troponin-I, and heart thiobarbituric acid reactive substances were significantly (p < 0.05) increased and heart superoxide dismutase and catalase activities were significantly (p < 0.05) reduced in isoproterenol-induced myocardial infarcted rats. Isoproterenol induction significantly (p < 0.05) elevated the plasma homocysteine and serum high sensitivity-C-reactive protein levels. Furthermore, an enzyme-linked immunosorbent assay, reverse transcription polymerase chain study, and immunohistochemical (IHC) staining revealed significantly (p < 0.05) elevated levels and expression of serum/myocardial nuclear factor-κB, tumor necrosis factor-alpha, interleukin-1 beta, and Interleukin-6 and significantly (p < 0.05) reduced levels/expression of serum/myocardial interleukin-10 in myocardial infarcted rats. Nevertheless, isoproterenol-induced rats treated with 3, 4-dihydroxybenzoic acid considerably (p < 0.05) attenuated all the biochemical, molecular, and IHC parameters investigated and inhibited oxidative stress and inflammation and protected the heart, through its antioxidant and anti-inflammatory mechanisms.

Artesunate attenuates isoprenaline induced cardiac hypertrophy in rats via SIRT1 inhibiting NF-κB activation.

Cardiac Hypertrophy is an adaptive response of the body to physiological and pathological stimuli, which increases cardiomyocyte size, thickening of cardiac muscles and progresses to heart failure. Downregulation of SIRT1 in cardiomyocytes has been linked with the pathogenesis of cardiac hypertrophy. The present study aimed to investigate the effect of Artesunate against isoprenaline induced cardiac hypertrophy in rats via SIRT1 inhibiting NF-κB activation. Experimental cardiac hypertrophy was induced in rats by subcutaneous administration of isoprenaline (5 mg/kg) for 14 days. Artesunate was administered simultaneously for 14 days at a dose of 25 mg/kg and 50 mg/kg. Artesunate administration showed significant dose dependent attenuation in mean arterial pressure, electrocardiogram, hypertrophy index and left ventricular wall thickness compared to the disease control group. It also alleviated cardiac injury biomarkers and oxidative stress. Histological observation showed amelioration of tissue injury in the artesunate treated groups compared to the disease control group. Further, artesunate treatment increased SIRT1 expression and decreased NF-kB expression in the heart. The results of the study show the cardioprotective effect of artesunate via SIRT1 inhibiting NF-κB activation in cardiomyocytes.

Compound 3K attenuates isoproterenol-induced cardiac hypertrophy by inhibiting pyruvate kinase M2 (PKM2) pathway.

AIM: Chronic sympathetic stimulation has been identified as a primary factor in the pathogenesis of cardiac hypertrophy (CH). However, there is no appropriate treatment available for the management of CH. Recently, it has been revealed that pyruvate kinase M2 (PKM2) plays a significant role in cardiac remodeling, fibrosis, and hypertrophy. However, the therapeutic potential of selective PKM2 inhibitor has not yet been explored in cardiac hypertrophy. Thus, in the current study, we have studied the cardioprotective potential of Compound 3K, a selective PKM2 inhibitor in isoproterenol-induced CH model. METHODS: To induce cardiac hypertrophy, male Wistar rats were subcutaneously administered isoproterenol (ISO, 5 mg/kg/day) for 14 days. Compound 3K at dosages of 2 and 4 mg/kg orally was administered to ISO-treated rats for 14 days to explore its effects on various parameters like ECG, ventricular functions, hypertrophic markers, histology, inflammation, and protein expression were performed. RESULTS: Fourteen days administration of ISO resulted in the induction of CH, which was evidenced by alterations in ECG, ventricular dysfunctions, increase in hypertrophy markers, and fibrosis. The immunoblotting of hypertrophy heart revealed the significant rise in PKM2 and reduction in PKM1 protein expression. Treatment with Compound 3K led to downregulation of PKM2 and upregulation of PKM1 protein expression. Compound 3K showed cardioprotective effects by improving ECG, cardiac functions, hypertrophy markers, inflammation, and fibrosis. Further, it also reduced cardiac expression of PKM2-associated splicing protein, HIF-1α, and caspase-3. CONCLUSION: Our findings suggest that Compound 3K has a potential cardioprotective effect via PKM2 inhibition in isoproterenol-induced CH.

A novel histone deacetylase inhibitor Se-SAHA attenuates isoproterenol-induced heart failure via antioxidative stress and autophagy inhibition.

Heart failure is associated with histone deacetylase (HDAC) regulation of gene expression, the inhibition of which is thought to be beneficial for heart failure therapy. Here, we explored the cardioprotective effects and underlying mechanism of a novel selenium-containing HDAC inhibitor, Se-SAHA, on isoproterenol (ISO)-induced heart failure. We found that pretreatment with Se-SAHA attenuated ISO-induced cardiac hypertrophy and fibrosis in neonatal rat ventricular myocytes (NRVMs). Se-SAHA significantly attenuated the generation of ISO-induced reactive oxygen species (ROS) and restored the expression levels of superoxide dismutase 2 (SOD2) and heme oxygenase-1 (HO-1) in vitro. Furthermore, Se-SAHA pretreatment prevented the accumulation of autophagosomes. Se-SAHA reversed the high expression of HDAC1 and HDAC6 induced by ISO incubation. However, after the addition of the HDAC agonist, the effect of Se-SAHA on blocking autophagy was inhibited. Using ISO-induced mouse models, cardiac ventricular contractile dysfunction, hypertrophy, and fibrosis was reduced treated by Se-SAHA. In addition, Se-SAHA inhibited HDAC1 and HDAC6 overexpression in ISO-treated mice. Se-SAHA treatment significantly increased the activity of SOD2 and improved the ability to eliminate free radicals. Se-SAHA hindered the excessive levels of the microtubule-associated protein 1 light chain 3 (LC3)-II and Beclin-1 in heart failure mice. Collectively, our results indicate that Se-SAHA exerts cardio-protection against ISO-induced heart failure via antioxidative stress and autophagy inhibition.

Effects of sacubitril-valsartan on remodelling, fibrosis and mitochondria in a murine model of isoproterenol-induced left ventricular dysfunction.

BACKGROUND: Sacubitril/valsartan has been demonstrated to promote left ventricular (LV) reverse remodelling and improve outcomes in patients with heart failure (HF) with reduced ejection fraction (EF). Its molecular and tissue effects have not been fully elucidated yet, due to the paucity of preclinical studies, mostly based on ischaemic models. We aimed to evaluate the effects of sacubitril/valsartan on LV remodelling, myocardial fibrosis and mitochondrial biology in a murine model of non-ischaemic LV dysfunction. METHODS: Adult transgenic male mice with cardiac-specific hyperaldosteronism (AS mice) received subcutaneous isoproterenol injections to induce LV systolic dysfunction. After 7 days, mice were randomized to a 2-week treatment with saline (ISO-AS n = 15), valsartan (ISO + V n = 12) or sacubitril/valsartan (ISO + S/V n = 12). Echocardiography was performed at baseline, at day 7, and after each of the 2 weeks of treatment. After sacrifice at day 21, histological and immunochemical assays were performed. A control group of AS mice was also obtained (Ctrl-AS n = 8). RESULTS: Treatment with sacubitril/valsartan, but not with valsartan, induced a significant improvement in LVEF (p = 0.009 vs ISO-AS) and fractional shortening (p = 0.032 vs ISO-AS) after 2- week treatment. In both ISO + V and ISO + S/V groups, a trend toward reduction of the cardiac collagen 1/3 expression ratio was detected. ISO + V and ISO + S/V groups showed a significant recovery of mitochondrial morphology and inner membrane function meant for oxidative phosphorylation. CONCLUSION: In a murine model of non-ischaemic HF, sacubitril/valsartan proved to have beneficial effects on LV systolic function, and on cardiac energetics, by improving mitochondrial activity.

Punicalagin attenuates isoproterenol-induced myocardial infarction through nuclear factor erythroid 2-related factor 2/silent information regulator transcript-1-mediated inhibition of inflammation and cardiac stress markers in experimental animal models.

Myocardial infarction (MI) is a significant global health issue and the leading cause of death. Myocardial infarction (MI) is characterized by events such as damage to heart cells and stress generated by inflammation. Punicalagin (PCN), a naturally occurring bioactive compound found in pomegranates, exhibits a diverse array of pharmacological effects against many disorders. This study aimed to assess the preventive impact of PCN, with its potential anti-inflammatory and antioxidant properties, on myocardial injury caused by isoproterenol (ISO) in rats and elucidate the possible underlying mechanisms. Experimental rats were randomly categorized into four groups: control group (fed a regular diet for 15 days), PCN group (orally administered PCN at 50 mg/kg body weight (b.w.) for 15 days), ISO group (subcutaneously administered ISO (85 mg/kg b.w.) on days 14 and 15 to induce MI), and PCN+ISO group (orally preadministered PCN (50 mg/kg b.w.) for 15 days and administered ISO (85 mg/kg b.w.) on days 14 and 15). The rat cardiac tissue was then investigated for cardiac marker, oxidative stress marker, and inflammatory marker expression levels. PCN prevented ISO-induced myocardial injury, suppressing the levels of creatine kinase-myocardial band, C-reactive protein, homocysteine, cardiac troponin T, and cardiac troponin I in the rats. Moreover, PCN treatment reversed (P<0.01) the ISO-induced increase in blood pressure, attenuated lipid peroxidation markers, and depleted both enzymatic and nonenzymatic markers in the rats. Additionally, PCN inhibited (P<0.01) ISO-induced overexpression of oxidative stress markers (p-38, p-c-Jun N-terminal kinase, and p-extracellular signal-regulated kinase 1), inflammatory markers (nuclear factor-kappa B, tumor necrosis factor-alpha, and interleukin-6), and matrix metalloproteinases and decreased the levels (P<0.01) of apoptosis proteins in the rats. Nuclear factor erythroid 2-related factor 2/silent information regulator transcript-1 (Nrf2/Sirt1) is a major cellular defense protein that regulates and scavenges oxidative toxic substances through apoptosis. Therefore, overexpression of Nrf2/Sirt1 to inhibit inflammation and oxidative stress is considered a novel target for preventing MI. PCN also significantly enhanced the expression of Nrf2/Sirt1 in ISO-induced rats. Histopathological analyses of cardiac tissue revealed that PCN treatment exhibited a protective effect on the heart tissue, mitigating damage. These findings show that by activating the Nrf2/Sirt1 pathway, PCN regulates oxidative stress, inflammation, and apoptosis, hence providing protection against ISO-induced myocardial ischemia.

Effects of dapagliflozin against streptozotocin and isoproterenol-induced heart failure via investigating NLRP3 and PPAR-γ signaling.

Heart failure is a condition in which the heart's one or both ventricles are unable to either receive an adequate amount of blood or eject an adequate amount of blood. Diabetes is considered one of the major risk factors for cardiovascular diseases. The current research is designed to evaluate the cardioprotective effects of dapagliflozin in streptozotocin and isoproterenol-induced comorbid rats. The COX-2, TNF-α, NF-КB, NLRP3, PPAR-γ, CKMB, TROP-I, AR, GP and SGLT were docked against dapagliflozin, propranolol and metformin. Dapagliflozin restored adequate blood flow and halted myofibril damage. Moreover, it's evident from this study that dapagliflozin significantly decreased serum concentration of various blood markers, decreased relative growth rate and QT interval prolongation, as compared to the negative control group. However, it improved the ventricular ejection fraction in rats of the treatment group. The GST, GSH and CAT levels were increased, as compared to normal. On the contrary, a decrease in LPO concentrations was observed. Evaluation of the coronal section of heart tissues showed the anti-inflammatory expressions evaluated through H & E staining and immunohistochemical techniques and with ELISA and PCR. In a nutshell, dapagliflozin reverses myocardial necrosis and apoptosis.

LncRNA GAS5 restrains ISO-induced cardiac fibrosis by modulating mir-217 regulation of SIRT1.

Considering the effect of SIRT1 on improving myocardial fibrosis and GAS5 inhibiting occurrence and development of myocardial fibrosis at the cellular level, the aim of the present study was to investigate whether LncRNA GAS5 could attenuate cardiac fibrosis through regulating mir-217/SIRT1, and whether the NLRP3 inflammasome activation was involved in this process. Isoprenaline (ISO) was given subcutaneously to the male C57BL/6 mice to induce myocardial fibrosis and the AAV9 vectors were randomly injected into the left ventricle of each mouse to overexpress GAS5. Primary myocardial fibroblasts (MCFs) derived from neonatal C57BL/6 mice and TGF-ß1 were used to induce fibrosis. And the GAS5 overexpressed MCFs were treated with mir-217 mimics and mir-217 inhibitor respectively. Then the assays of expression levels of NLRP3, Caspase-1, IL-1ß and SIRT1 were conducted. The findings indicated that the overexpression of GAS5 reduced the expression levels of collagen, NLRP3, Capase-1, IL-1ß and SIRT1 in ISO treated mice and TGF-ß1 treated MCFs. However, this effect was significantly weakened after mir-217 overexpression, but was further enhanced after knockdown of mir-217. mir-217 down-regulates the expression of SIRT1, leading to increased activation of the NLRP3 inflammasome and subsequent pyroptosis. LncRNA GAS5 alleviates cardiac fibrosis induced via regulating mir-217/SIRT1 pathway.

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.

Cardioprotective potential of compound 3K, a selective PKM2 inhibitor in isoproterenol-induced acute myocardial infarction: A mechanistic study.

Myocardial infarction (MI) or heart attack arises from acute or chronic prolonged ischemic conditions in the myocardium. Although several risk factors are associated with MI pathophysiology, one of the risk factors is an imbalance in the oxygen supply. The current available MI therapies are still inadequate due to the complexity of MI pathophysiology. Pyruvate kinase M2 (PKM2) has been implicated in numerous CVDs pathologies. However, the effect of specific pharmacological intervention targeting PKM2 has not been studied in MI. Therefore, in this study, we explored the effect of compound 3K, a PKM2-specific inhibitor, in isoproterenol-induced acute MI model. In this study, in order to induce MI in rats, isoproterenol (ISO) was administered at a dose of 100 mg/kg over two days at an interval of 24 h. Specific PKM2 inhibitor, compound 3K (2 and 4 mg/kg), was administered in MI rats to investigate its cardioprotective potential. After the last administration of compound 3K, ECG and hemodynamic parameters were recorded using a PV-loop system. Cardiac histology, western blotting, and plasmatic cardiac damage markers were evaluated to elucidate the underlying mechanisms. Treatment of compound 3K significantly reduced ISO-induced alterations in ECG, ventricular functions, cardiac damage, infarct size, and cardiac fibrosis. Compound 3K treatment produced significant increase in PKM1 expression and decrease in PKM2 expression. In addition, HIF-1α, caspase-3, c-Myc, and PTBP1 expression were also reduced after compound 3K treatment. This study demonstrates the cardioprotective potential of compound 3K in MI, and its mechanisms of cardioprotective action.

mTORC1 hyperactivation and resultant suppression of macroautophagy contribute to the induction of cardiomyocyte necroptosis by catecholamine surges.

Previous studies revealed a controversial role of mechanistic target of rapamycin complex 1 (mTORC1) and mTORC1-regulated macroautophagy in isoproterenol (ISO)-induced cardiac injury. Here we investigated the role of mTORC1 and potential underlying mechanisms in ISO-induced cardiomyocyte necrosis. Two consecutive daily injections of ISO (85 mg/kg, s.c.) or vehicle control (CTL) were administered to C57BL/6J mice with or without rapamycin (RAP, 5 mg/kg, i.p.) pretreatment. Western blot analyses showed that myocardial mTORC1 signaling and the RIPK1-RIPK3-MLKL necroptotic pathway were activated, mRNA expression analyses revealed downregulation of representative TFEB target genes, and Evan's blue dye uptake assays detected increased cardiomyocyte necrosis in ISO-treated mice. However, RAP pretreatment prevented or significantly attenuated the ISO-induced cardiomyocyte necrosis, myocardial inflammation, downregulation of TFEB target genes, and activation of the RIPK1-RIPK3-MLKL pathway. LC3-II flux assays confirmed the impairment of myocardial autophagic flux in the ISO-treated mice. In cultured neonatal rat cardiomyocytes, mTORC1 signaling was also activated by ISO, and inhibition of mTORC1 by RAP attenuated ISO-induced cytotoxicity. These findings suggest that mTORC1 hyperactivation and resultant suppression of macroautophagy play a major role in the induction of cardiomyocyte necroptosis by catecholamine surges, identifying mTORC1 inhibition as a potential strategy to treat heart diseases with catecholamine surges.

Cardioprotective effects of p-coumaric acid on tachycardia, inflammation, ion pump dysfunction, and electrolyte imbalance in isoproterenol-induced experimental myocardial infarction.

Cardiovascular diseases cause a large number of deaths throughout the world. No research was conducted earlier on p-coumaric acid's effect on tachycardia, inflammation, ion pump dysfunction, and electrolyte imbalance. Hence, we appraised the above-said parameters in isoproterenol-induced myocardial infarcted rats. This investigation included 24 male albino Wistar rats in 4 groups. Normal control Group 1, p-coumaric acid (8 mg/kg body weight) alone treated Group 2, Isoproterenol (100 mg/kg body weight) induced myocardial infarcted Group 3, p-coumaric acid (8 mg/kg body weight) pretreated isoproterenol (100 mg/kg body weight) induced Group 4. After 1 day of the last dose of isoproterenol injection (day 10), rats were killed and blood and heart were taken and inflammatory markers, lipid peroxidation, nonenzymatic antioxidants, ion pumps, and electrolytes were measured. The heart rate, serum cardiac troponin-T, serum/plasma inflammatory markers, and heart proinflammatory cytokines were raised in isoproterenol-induced rats. Isoproterenol also enhanced plasma lipid peroxidation, lessened plasma nonenzymatic antioxidants, and altered heart ion pumps and serum and heart electrolytes. In this study, p-coumaric acid pretreatment orally for 7 days to isoproterenol-induced myocardial infarcted rats prevented changes in the above-cited parameters. p-Coumaric acid's anti-tachycardial, anti-inflammatory, anti-ion pump dysfunction and anti-electrolyte imbalance properties are the mechanisms for these cardioprotective effects.

Chlorogenic Acid Attenuates Isoproterenol Hydrochloride-Induced Cardiac Hypertrophy in AC16 Cells by Inhibiting the Wnt/ß-Catenin Signaling Pathway.

Cardiac hypertrophy (CH) is an important characteristic in heart failure development. Chlorogenic acid (CGA), a crucial bioactive compound from honeysuckle, is reported to protect against CH. However, its underlying mechanism of action remains incompletely elucidated. Therefore, this study aimed to explore the mechanism underlying the protective effect of CGA on CH. This study established a CH model by stimulating AC16 cells with isoproterenol (Iso). The observed significant decrease in cell surface area, evaluated through fluorescence staining, along with the downregulation of CH-related markers, including atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and ß-myosin heavy chain (ß-MHC) at both mRNA and protein levels, provide compelling evidence of the protective effect of CGA against isoproterenol-induced CH. Mechanistically, CGA induced the expression of glycogen synthase kinase 3ß (GSK-3ß) while concurrently attenuating the expression of the core protein ß-catenin in the Wnt/ß-catenin signaling pathway. Furthermore, the experiment utilized the Wnt signaling activator IM-12 to observe its ability to modulate the impact of CGA pretreatment on the development of CH. Using the Gene Expression Omnibus (GEO) database combined with online platforms and tools, this study identified Wnt-related genes influenced by CGA in hypertrophic cardiomyopathy (HCM) and further validated the correlation between CGA and the Wnt/ß-catenin signaling pathway in CH. This result provides new insights into the molecular mechanisms underlying the protective effect of CGA against CH, indicating CGA as a promising candidate for the prevention and treatment of heart diseases.

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.

Effect of plasma exosome lncRNA on isoproterenol hydrochloride-induced cardiotoxicity in rats.

Isoprenaline hydrochloride (IH) is a ß-adrenergic receptor agonist commonly used in the treatment of hypotension, shock, asthma, and other diseases. However, IH-induced cardiotoxicity limits its application. A large number of studies have shown that long noncoding RNA (lncRNA) regulates the occurrence and development of cardiovascular diseases. This study aimed to investigate whether abnormal lncRNA expression is involved in IH-mediated cardiotoxicity. First, the Sprague-Dawley (SD) rat myocardial injury model was established. Circulating exosomes were extracted from the plasma of rats and identified. In total, 108 differentially expressed (DE) lncRNAs and 150 DE mRNAs were identified by sequencing. These results indicate that these lncRNAs and mRNAs are substantially involved in chemical cardiotoxicity. Further signaling pathway and functional studies indicated that lncRNAs and mRNAs regulate several biological processes, such as selective mRNA splicing through spliceosomes, participate in sphingolipid metabolic pathways, and play a certain role in the circulatory system. Finally, we obtained 3 upregulated lncRNAs through reverse transcription-quantitative PCR (RT-qPCR) verification and selected target lncRNA-mRNA pairs according to the regulatory relationship of lncRNA/mRNA, some of which were associated with myocardial injury. This study provides valuable insights into the role of lncRNAs as novel biomarkers of chemical-induced cardiotoxicity.

The water extract of Amydrium sinense (Engl.) H. Li ameliorates Isoproterenol-induced cardiac hypertrophy through inhibiting the NF-κB signaling pathway.

OBJECTIVE: Pathologic cardiac hypertrophy (PCH) is a precursor to heart failure. Amydrium sinense (Engl.) H. Li (AS), a traditional Chinese medicinal plant, has been extensively utilized to treat chronic inflammatory diseases. However, the therapeutic effect of ASWE on PCH and its underlying mechanisms are still not fully understood. METHODS: A cardiac hypertrophy model was established by treating C57BL/6 J mice and neonatal rat cardiomyocytes (NRCMs) in vitro with isoprenaline (ISO) in this study. The antihypertrophic effects of AS water extract (ASWE) on cardiac function, histopathologic manifestations, cell surface area and expression levels of hypertrophic biomarkers were examined. Subsequently, the impact of ASWE on inflammatory factors, p65 nuclear translocation and NF-κB activation was investigated to elucidate the underlying mechanisms. RESULTS: In the present study, we observed that oral administration of ASWE effectively improved ISO-induced cardiac hypertrophy in mice, as evidenced by histopathological manifestations and the expression levels of hypertrophic markers. Furthermore, the in vitro experiments demonstrated that ASWE treatment inhibited cardiac hypertrophy and suppressed inflammation response in ISO-treated NRCMs. Mechanically, our findings provided evidence that ASWE suppressed inflammation response by repressing p65 nuclear translocation and NF-κB activation. ASWE was found to possess the capability of inhibiting inflammation response and cardiac hypertrophy induced by ISO. CONCLUSION: To sum up, ASWE treatment was shown to attenuate ISO-induced cardiac hypertrophy by inhibiting cardiac inflammation via preventing the activation of the NF-kB signaling pathway. These findings provided scientific evidence for the development of ASWE as a novel therapeutic drug for PCH treatment.

Effect of folic acid on isoprenaline-induced myocardial injury in rats.

Background: Isoprenaline (ISO), a synthetic catecholamine and a ß-adrenoceptor agonist, is widely used to develop an experimental model of myocardial injury (MI) in rats. The leading hypothesis for ISO-induced MI in rats is that it results from catecholamine overstimulation, oxidative stress, inflammatory responses, and development of cardiomyopathy during ISO administration. Folic acid (FA) reduces oxidative stress, improves endothelial function and prevents apoptosis, thereby contributing to cardiovascular protection. This study aimed to investigate the potentially protective effect of FA pretreatment on ISO-induced MI in rats. Methods: For 7 days, adult male Wistar albino rats were pretreated with 5 mg/kg/day of FA. On the sixth and seventh days, MI in rats was induced by administering 85 mg/kg/day of ISO. Prooxidant markers in plasma samples, antioxidant capacity in erythrocyte lysates, cardiac damage markers, lipid profile, electrocardiography (ECG) and histopathological analysis were evaluated. Results: FA pretreatment significantly alleviated changes induced by ISO; it decreased the homocysteine and high-sensitivity troponin I level. FA moderately decreased the reactive oxygen species (ROS) levels (superoxide anion radical, hydrogen peroxide and thiobarbituric acid reactive substances) and improved the antioxidant activities of catalase, superoxide dismutase and reduced glutathione. ISO reduced the nitrite level and FA significantly alleviated this change. Conclusion: It can be concluded that FA, as a mild antioxidant, could be an appropriate cardioprotective substance in the rat model of ISO-induced MI.

Inhibition of Pyruvate kinase M2 (PKM2) by shikonin attenuates isoproterenol-induced acute myocardial infarction via reduction in inflammation, hypoxia, apoptosis, and fibrosis.

Myocardial infarction (MI) is a major cause of mortality and disability globally. MI results from acute or chronic myocardial ischemia characterized by an imbalance of oxygen demand and supply, leading to irreversible myocardial injury. Despite several significant efforts in the understanding of MI, the therapy of MI is not satisfactory due to its complicated pathophysiology. Recently, therapeutic potential of targeting pyruvate kinase M2 (PKM2) has been postulated in several cardiovascular diseases. PKM2 gene knockout and expression studies implicated the role of PKM2 in MI. However, the effects of pharmacological interventions targeting PKM2 have not been investigated in MI. Therefore, in the present study, effect of PKM2 inhibitor has been investigated in the MI along with elucidation of possible mechanism(s). MI in rats was induced by administrations of isoproterenol (ISO) at a dose of 100 mg/kg s.c. for two consecutives days at 24-h interval. At the same time, shikonin (PKM2 inhibitor) was administered at 2 and 4 mg/kg in ISO-induced MI rats. After the shikonin treatment, the ventricular functions were measured using a PV-loop system. Plasma MI injury markers, cardiac histology, and immunoblotting were performed to elucidate the molecular mechanism. Treatment of shikonin 2 and 4 mg/kg ameliorated cardiac injury, reduced infarct size, biochemical alterations, ventricular dysfunction, and cardiac fibrosis in ISO-induced MI. Expression of PKM2 in the ventricle was reduced while PKM1 expression increased in the shikonin treated group, indicating PKM2 inhibition restores PKM1 expression. In addition, PKM splicing protein (hnRNPA2B1 & PTBP1), HIF-1α, and caspase-3 expression were reduced after shikonin treatment. Our findings suggest that pharmacological inhibition of PKM2 with shikonin could be a potential therapeutic strategy to treat MI.

Isoproterenol induces MD2 activation by ß-AR-cAMP-PKA-ROS signalling axis in cardiomyocytes and macrophages drives inflammatory heart failure.

Cardiac inflammation contributes to heart failure (HF) induced by isoproterenol (ISO) through activating ß-adrenergic receptors (ß-AR). Recent evidence shows that myeloid differentiation factor 2 (MD2), a key protein in endotoxin-induced inflammation, mediates inflammatory heart diseases. In this study, we investigated the role of MD2 in ISO-ß-AR-induced heart injuries and HF. Mice were infused with ISO (30 mg·kg-1·d-1) via osmotic mini-pumps for 2 weeks. We showed that MD2 in cardiomyocytes and cardiac macrophages was significantly increased and activated in the heart tissues of ISO-challenged mice. Either MD2 knockout or administration of MD2 inhibitor L6H21 (10 mg/kg every 2 days, i.g.) could prevent mouse hearts from ISO-induced inflammation, remodelling and dysfunction. Bone marrow transplantation study revealed that both cardiomyocyte MD2 and bone marrow-derived macrophage MD2 contributed to ISO-induced cardiac inflammation and injuries. In ISO-treated H9c2 cardiomyocyte-like cells, neonatal rat primary cardiomyocytes and primary mouse peritoneal macrophages, MD2 knockout or pre-treatment with L6H21 (10 µM) alleviated ISO-induced inflammatory responses, and the conditioned medium from ISO-challenged macrophages promoted the hypertrophy and fibrosis in cardiomyocytes and fibroblasts. We demonstrated that ISO induced MD2 activation in cardiomyocytes via ß1-AR-cAMP-PKA-ROS signalling axis, and induced inflammatory responses in macrophages via ß2-AR-cAMP-PKA-ROS axis. This study identifies MD2 as a key inflammatory mediator and a promising therapeutic target for ISO-induced heart failure.

The Detrimental Effect of Pre-Treatment with Ivermectin on Myocardial Ischemia.

INTRODUCTION: Ivermectin (IVM) is a broad-spectrum anti-parasitic agent with potential antibacterial, antiviral, and anti-cancer effects. There are limited studies on the effects of IVM on cardiovascular diseases, so the present study sought to determine the effects of pre-treatment with IVM on myocardial ischemia in both ex vivo and in vivo. METHODS: In the ex vivo part, two groups of control and treated rats with IVM (0.2 mg/kg) were examined for cardiac function and arrhythmias by isolated heart perfusion. In the in vivo part, four groups, namely, control, IVM, Iso (MI), and Iso + IVM 0.2 mg/kg were used. Subcutaneous injection of isoproterenol (100 mg/kg/day) for 2 consecutive days was used for the induction of myocardial infarction (MI) in male Wistar rats. Then electrocardiogram, hemodynamic factors, cardiac hypertrophy, and malondialdehyde (MDA) levels were investigated. RESULTS: The ex vivo results showed that administration of IVM induces cardiac arrhythmia and decreases the left ventricular maximal rate of pressure increase (contractility) and maximal rate of pressure decline (relaxation). The isoproterenol-induced MI model used as an in vivo model showed that cardiac hypertrophy were increased with no improvement in the hemodynamic and electrocardiogram pattern in the IVM-treated group in comparison to MI (Iso) group. However, the MDA level was lower in the IVM-treated group. CONCLUSION: IVM pre-treatment demonstrates detrimental effects in cardiac ischemia through exacerbation of cardiac arrhythmia, myocardial dysfunction, and increased cardiac hypertrophy. Therefore, the use of IVM in ischemic heart patients should be done with great caution.