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Background Myocardial fibrosis is caused by the adverse and powerful remodeling of the heart secondary to the death of cardiomyocytes after myocardial infarction. Regulators of G protein Signaling (RGS) 4 is involved in cardiac diseases through regulating G protein-coupled receptors (GPCRs). Methods Cardiac fibrosis models were established through cardiac fibroblasts (CFs) treatment with transforming growth factor (TGF)-β1 in vitro and mice subjected to myocardial infarction in vivo. The mRNA expression of RGS4, collagen I/III and α-SMA detected by qRT-PCR. Protein level of RGS4, collagen I, CTGF and α-SMA detected by Western blot. The ejection fraction (EF%) and fractional shortening (FS%) of mice were measured by echocardiography. Collagen deposition of mice was tested by Masson staining. Results The expression of RGS4 increased in CFs treatment with TGF-β1 and in MI mice. The model of cardiac fibrosis detected by qRT-PCR and Western blot. It was demonstrated that inhibition of RGS4 expression improved cardiac fibrosis by transfection with small interfering RNA in CFs and injection with lentivirus shRNA in mice. The protective effect of choline against cardiac fibrosis was counteracted by overexpression of RGS4 in vitro and in vivo. Moreover, choline inhibited the protein level of TGF-β1, p-Smad2/3, p-p38 and p-ERK1/2 in CFs treated with TGF-β1, which were restored by RGS4 overexpression. Conclusion This study demonstrated that RGS4 promoted cardiac fibrosis and attenuated the anti-cardiac fibrosis of choline. RGS4 may weaken anti-cardiac fibrosis of choline through TGF-β1/Smad and MAPK signaling pathways.

Hyperlipidemia (HPL) characterized by metabolic disorder of lipids and cholesterol is one of the important risk factors for cardiovascular diseases. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a potent circulating regulator of LDL through its ability to induce degradation of the low-density lipoprotein cholesterol receptor (LDLR) in the lysosome of hepatocytes. Aloe-emodin (AE) is one of potentially bioactive components of Chinese traditional medicine Daming capsule. In this study we evaluated the HPL-lowering efficacy of AE in both in vivo and in vitro HPL models. High-fat diet-induced rats were treated with AE (100 mg/kg per day, ig) for 6 weeks. We found that AE administration significantly decreased the levels of total cholesterol (TC) and LDL in the serum and liver tissues. Moreover, AE administration ameliorated HPL-induced hepatic lipid aggregation. But AE administration did not significantly inhibit HMG-CoA reductase activity in the liver of HPL rats. A cellular model of HPL was established in human hepatoma (HepG2) cells treated with cholesterol (20 μg/mL) and 25-hydroxycholesterol (2 μg/mL), which exhibited markedly elevated cholesterol levels. The increased cholesterol levels could be reversed by subsequent treatment with AE (30 μM). In both the in vivo and in vitro HPL models, we revealed that AE selectively suppressed the sterol-regulatory element-binding protein-2 (SREBP-2) and hepatocyte nuclear factor (HNF)1α-mediated PCSK9 signaling, which in turn upregulated LDL receptor (LDLR) and promoted LDL uptake. This study demonstrates that AE reduces cholesterol content in HPL rats by inhibiting the hepatic PCSK9/LDLR pathway.

Brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase B (TrkB) pathway is associated with ischemic heart diseases (IHD). 7,8-dihydroxyflavone (7,8-DHF), BDNF mimetic, is a potent agonist of TrkB. We aimed to investigate the effects and the underlying mechanisms of 7,8-DHF on cardiac ischemia. Myocardial ischemic mouse model was induced by ligation of left anterior descending coronary artery. 7,8-DHF (5 mg/kg) was administered intraperitoneally two days after ischemia for four weeks. Echocardiography, HE staining and transmission electron microscope were used to examine the function, histology and ultrastructure of the heart. H9c2 cells were treated with hydrogen peroxide (H2O2), 7,8-DHF or TrkB inhibitor ANA-12. The effects of 7,8-DHF on cell viability, mitochondrial membrane potential (MMP) and mitochondrial superoxide generation were examined. Furthermore, mitochondrial fission and protein expression of mitochondrial dynamics (Mfn2 [mitofusin 2], OPA1 [optic atrophy 1], Drp1 [dynamin-related protein 1] and Fis-1 [fission 1]) was detected by mitotracker green staining and western blot, respectively. 7,8-DHF attenuated cardiac dysfunction and cardiomyocyte abnormality of myocardial ischemic mice. Moreover, 7,8-DHF increased cell viability and reduced cell death accompanied by improving MMP, inhibiting mitochondrial superoxide and preventing excessive mitochondrial fission of H2O2-treated H9c2 cells. The cytoprotective effects of 7,8-DHF were antagonized by ANA-12. Mechanistically, 7,8-DHF repressed OMA1-dependent conversion of L-OPA1 into S-OPA1, which was abolished by Akt inhibitor. In conclusion, 7,8-DHF protects against cardiac ischemic injury by inhibiting the proteolytic cleavage of OPA1. These findings provide a novel pharmacological effect of 7,8-DHF on mitochondrial dynamics and a new potential target for IHD.

Background and purpose Doxorubicin (Dox)-induced cardiotoxicity limits its clinical use. A number of microRNAs (miRs) have been found essential in Dox-induced cardiotoxicity. The aim of the present study was to elucidate the effects of miR-23a on Dox-induced cardiomyocyte apoptosis and underlying mechanisms. Experimental approach Dox-induced cardiotoxicity model was established in primary neonatal rat ventricular myocytes (NRVMs). MTT assay, Live/Dead staining was employed to examine the viability and cell death of NRVMs. Mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) were measured. Protein levels of mitochondria biogenesis and fission/fusion associated factors including peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α), dynamin-related protein-1 (Drp1) and mitofusin 2 (Mfn2) were detected. Meanwhile, apoptosis-related cytochrome c (Cyt c) and caspase-3 expression were examined by western blot. PGC-1α siRNA was employed to validate the role of miR-23a in Dox-induced cardiotoxicity. Key results MiR-23a expression was significantly increased by Dox concentration-dependently. Inhibition of miR-23a markedly increased viability and MMP, reduced cell death and ROS production of NRVMs. MiR-23a mimic significantly inhibited expression of its target PGC-1α. MiR-23a inhibitor significantly diminished phosphorylation of Drp1 without affecting Mfn2 expression. Protein expression of Cyt c and cleaved caspase-3 were markedly inhibited by miR-23a inhibitor. The protective effects of miR-23a inhibitor were reversed by PGC-1α siRNA. Conclusions and implications Increased miR-23a promoted mitochondrial injury in the Dox-induced cellular model. Inhibition of miR-23a attenuated cardiomyocyte damage by directly targeting PGC-1α/p-Drp1, thereby inhibiting mitochondria-dependent apoptosis. These findings may provide a new potential target for the treatment of Dox-induced cardiotoxicity.

Additional file of The association between RGS4 and choline in cardiac fibrosis

Additional file 3. Hematoxylin-eosin (H&E)-staining of heart tissue in MI mice.

Additional file 1. The RGS4 protein level after knocking down and overexpression.

Backgroud/Aims: Growing evidence suggests that both cardiomyocyte apoptosis and excessive autophagy exacerbates cardiac dysfunction during myocardial ischemia-reperfusion (IR). As a precursor of acetylcholine, choline has been found to protect the heart by repressing ischemic cardiomyocyte apoptosis. However, the relationship between choline and cardiomyocyte autophagy is unclear. The present study aimed to investigate whether autophagy was involved in the cardioprotection of choline during IR. Methods: Rats were subjected to 30 min reversible ischemia by ligation of left anterior descending coronary artery followed by reperfusion for 2 h. Choline (5 mg/kg, i.v.) alone or along with rapamycin (5 mg/ kg, i.p.) were injected 30 min before ischemia. Transmission electron microscopy, hematoxylin and eosin (HE) and TUNEL staining were conducted to evaluate the effect of choline on cardiac apoptosis and autophagy. Protein levels of autophagic markers including LC3, beclin-1 and p62 as well as Akt and mammalian target of rapamycin (mTOR) were examined by Western blotting. Results: Myocardial IR-induced cardiac apoptosis and accumulation of autophagosomes was attenuated by choline. Choline treatment significantly ameliorated myocardial IR-induced autophagic activity characterized by repression of beclin-1 over-activation, the reduction of autophagosomes, the LC3-II/LC3-I ratio, and p62 protein abundance. In addition, IR-induced downregulation of p-Akt/mTOR cascade was increased by choline. However, the above functions of choline were abolished by rapamycin. Conclusion: These findings suggest that choline plays a protective role against myocardial IR injury by inhibiting excessive autophagy, which might be associated with the activation of Akt/mTOR pathway. This study provides new mechanistic understanding of cardioprotective effect of choline and suggests novel potential therapeutic targets for cardiac IR injury.

Cardiotoxicity is one of the primary limitations in the clinical use of the anticancer drug doxorubicin (DOX). However, the role of microRNAs (miRNAs) in DOX-induced cardiomyocyte death has not yet been covered. To investigate this, we observed a significant increase in miR-98 expression in neonatal rat ventricular myocytes after DOX treatment, and MTT, LIVE/Dead and Viability/Cytotoxicity staining showed that miR-98 mimic inhibited DOX-induced cell death. This was also confirmed by Flow cytometry and Annexin V-FITC/PI staining. Interestingly, the protein expression of caspase-8 was upregulated by miR-98 mimics during this process, whereas Fas and RIP3 were downregulated. In addition, the effect of miR-98 against the expression of Fas and RIP3 were restored by the specific caspase-8 inhibitor Z-IETD-FMK. Thus, we demonstrate that miR-98 protects cardiomyocytes from DOX-induced injury by regulating the caspase-8-dependent Fas/RIP3 pathway. Our findings enhance understanding of the therapeutic role of miRNAs in the treatment of DOX-induced cardiotoxicity.

MicroRNAs (miRNAs) are small conserved noncoding RNAs which function as posttranscriptional regulators of gene expression. Studies over the last 20 years have revealed the essential functions of miRNAs in regulating cardiovascular biology (such as cardiovascular cell differentiation, growth, proliferation and apoptosis) and crucial roles in controlling cardiovascular disease (CVD), indicating the potential of these small molecules as therapeutic targets and/or agents for CVD. Moreover, miRNAs in the circulation or other body fluids are stable and readily detectable, and more importantly often disease-associated, which makes them promising novel biomarkers for diagnosis and prognosis of CVDs. Furthermore, emerging evidence uncovered miRNAs as new targets and/or regulators of cardiovascular medications given the ability of miRNAs to interact with some cardiovascular drugs, which opens up new opportunities for the research and development of novel CVD drugs. Herein, we summarize current knowledge regarding the potential applications of miRNAs in the therapy of CVD, including myocardial ischemia, cardiac hypertrophy/heart failure, interstitial fibrosis, arrhythmia, diabetes and hypertension and discuss the therapeutic potential and challenge of miRNAs in drug discovery.

Background/Aims: High-fat diet (HFD) causes cardiac electrical remodeling and increases the risk of ventricular arrhythmias. Aloe-emodin (AE) is an anthraquinone component isolated from rhubarb and has a similar chemical structure with emodin. The protective effect of emodin against cardiac diseases has been reported in the literature. However, the cardioprotective property of AE is still unknown. The present study investigated the effect of AE on HFD-induced QT prolongation in rats. Methods: Adult male Wistar rats were randomly divided into three groups: control, HFD, and AE-treatment groups. Normal diet was given to rats in the control group, high-fat diet was given to rats in HFD and AE-treatment groups for a total of 10 weeks. First, HFD rats and AE-treatment rats were fed with high-fat diet for 4 weeks to establish the HFD model. Serum total cholesterol and triglyceride levels were measured to validate the HFD model. Afterward, AE-treatment rats were intragastrically administered with 100 mg/kg AE each day for 6 weeks. Electrocardiogram monitoring and whole-cell patch-clamp technique were applied to examine cardiac electrical activity, action potential and inward rectifier K+ current (IK1), respectively. Neonatal rat ventricular myocytes (NRVMs) were subjected to cholesterol and/or AE. Protein expression of Kir2.1 was detected by Western blot and miR-1 level was examined by real-time PCR in vivo and in vitro, respectively. Results: In vivo, AE significantly shortened the QT interval, action potential duration at 90% repolarization (APD90) and resting membrane potential (RMP), which were markedly elongated by HFD. AE increased IK1 current and Kir2.1 protein expression which were reduced in HFD rats. Furthermore, AE significantly inhibited pro-arrhythmic miR-1 in the hearts of HFD rats. In vitro, AE decreased miR-1 expression levels resulting in an increase of Kir2.1 protein levels in cholesterol-enriched NRVMs. Conclusions: AE prevents HFD-induced QT prolongation by repressing miR-1 and upregulating its target Kir2.1. These findings suggest a novel pharmacological role of AE in HFD-induced cardiac electrical remodeling.

The clinical application of doxorubicin (Dox) is limited by its adverse effect of cardiotoxicity. Previous studies have suggested the cardioprotective effect of brain‐derived neurotrophic factor (BDNF). We hypothesize that BDNF could protect against Dox‐induced cardiotoxicity. Sprague Dawley rats were injected with Dox (2.5 mg/kg, 3 times/week, i.p.), in the presence or absence of recombinant BDNF (0.4 μg/kg, i.v.) for 2 weeks. H9c2 cells were treated with Dox (1 μM) and/or BDNF (400 ng/ml) for 24 hrs. Functional roles of BDNF against Dox‐induced cardiac injury were examined both in vivo and in vitro. Protein level of BDNF was reduced in Dox‐treated rat ventricles, whereas BDNF and its receptor tropomyosin‐related kinase B (TrkB) were markedly up‐regulated after BDNF administration. Brain‐derived neurotrophic factor significantly inhibited Dox‐induced cardiomyocyte apoptosis, oxidative stress and cardiac dysfunction in rats. Meanwhile, BDNF increased cell viability, inhibited apoptosis and DNA damage of Dox‐treated H9c2 cells. Investigations of the underlying mechanisms revealed that BDNF activated Akt and preserved phosphorylation of mammalian target of rapamycin and Bad without affecting p38 mitogen‐activated protein kinase and extracellular regulated protein kinase pathways. Furthermore, the beneficial effect of BDNF was abolished by BDNF scavenger TrkB‐Fc or Akt inhibitor. In conclusion, our findings reveal a potent protective role of BDNF against Dox‐induced cardiotoxicity by activating Akt signalling, which may facilitate the safe use of Dox in cancer treatment.

Background/Aims Zidovudine (3′-azido-2′,3′-deoxythymidine; AZT) is a first-line drug for treatment of human immunodeficiency virus infection (HIV). However, its application is limited by cardiotoxicity due to cardiomyocyte injury. This study investigated whether Aloe-emodin (AE), an anthraquinone compound, protects against AZT-induced cardiomyocyte toxicity. Methods MTT, JC-1 assays and TUNEL were examined to verify the protective effect of AE against AZT-induced cardiomyocyte injury. Western blotting was performed to explore the anti-apoptotic effect of AE using anti-apoptotic proteins p90rsk, p-bad, and bcl-2 and pro-apoptotic proteins apaf-1, cleaved-caspase-3, and cytochrome c. Results We observed a protective effect of AE against cell viability decrease and TUNEL positive cells increase induced by AZT, which was counteracted by BI-D1870. Western blot analysis found that AE significantly inhibited cardiomyocyte apoptosis by activating p90rsk/p-bad/bcl-2 signaling pathway. Furthermore, BI-D1870 counteracted the anti-apoptotic effect of AE. Conclusions Taken together, these results indicate that AE attenuated AZT-induced cardiomyocyte apoptosis by activating p90rsk.

Nav1.1 and Nav1.2 are the voltage-gated sodium channel alpha subunit1 and 2, encoded by the genes of SCN1A and SCN2A. Previous studies have shown that chronic cerebral hypoperfusion (CCH) could induce neuropathological and cognitive impairment and increased total Nav1.1 and Nav1.2protein levels, yet the detailed mechanisms are not fully understood. MicroRNAs (miRNAs) are a class of small, non-coding RNAs that are involved in the regulation of dementia. miR-132 is known to play a key role in neurodegenerative disease. Here, we determined that miR-132 regulates Nav1.1 and Nav1.2 under CCH state. In this study, the expression of miR-132 was decreased in both the hippocampus and cortex of ratsfollowing CCH generated by bilateral common carotid artery occlusion (2VO). Lentiviral-mediated overexpression of miR-132 ameliorated dementia vulnerability induced by 2VO. At the molecular level, miR-132 repressed the increased protein expression of Nav1.1 and Nav1.2 in both the hippocampus and cortex induced by 2VO. MiR-132 suppressed, while AMO-miR-132 enhanced, the level of Nav1.1 and Nav1.2 in primary cultured neonatal rat neurons (NRNs) detected by both western blot analysis and immunofluorescence analysis. Results obtained by dual luciferase assay showed that overexpression of miR-132 inhibited the expression of Nav1.1 and Nav1.2 in human embryonic kidney 293 (HEK293T) cells. Additionally, binding-site mutation failed to influence Nav1.1 and Nav1.2, indicating that Nav1.1 and Nav1.2 are potential targets for miR-132. Taken together, our findings demonstrated that miR-132 protects against CCH-induced learning and memory impairments by down-regulating the expression of Nav1.1 and Nav1.2, and SCN1A and SCN2A are the target genes of miR-132.

Background: Our previous studies suggested that brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase B (TrkB) axis inhibited cardiomyocyte apoptosis in myocardial infarction (MI). However, the relationship between BDNF and microRNA (miRNA) in cardiomyocytes are unclear. The present study was performed to investigate the role of miR-195 and the interplay between BDNF and miR-195 in ischemic cardiomyocyte apoptosis. Methods: Male Wistar rats were subjected to coronary artery ligation, and primary neonatal rat ventricular myocytes were treated with hypoxia or hydrogen peroxide (H2O2). BDNF level in rat ventricles was measured by enzyme linked immunosorbent assay (ELISA). miR-195 mimic, inhibitor or negative control was transfected into the cardiomyocytes. Cell viability and apoptosis were detected by MTT assay and TdT-mediated dUTP nick end labeling (TUNEL) staining, respectively. Cardiac function and apoptosis were detected in MI rats intravenously injected with antagomiR-195. Luciferase assay, Western blot and Real-time RT-PCR were employed to clarify the interplay between miR-195 and BDNF. Results: miR-195 level was dynamically regulated in response to MI and significantly increased in ischemic regions 24 h post-MI as well as in hypoxic or H2O2-treated cardiomyocytes. Meanwhile, BDNF protein level was rapidly increased in MI rats and H2O2-treated cardiomyocytes. Apoptosis in both hypoxic and H2O2-treated cardiomyocytes were markedly reduced and cell viability was increased by miR-195 inhibitor. Moreover, inhibition of miR-195 significantly improved cardiac function of MI rats. Bcl-2 but not BDNF was validated as the direct target of miR-195. Furthermore, BDNF abolished the pro-apoptotic role of miR-195, which was reversed by its scavenger TrkB-Fc. Conclusion: Up-regulation of miR-195 in ischemic cardiomyocytes promotes ischemic apoptosis by targeting Bcl-2. BDNF mitigated the pro-apoptotic effect of miR-195 in rat cardiomyocytes. These findings may provide better understanding of the pro-apoptotic role of miR-195 in MI and suggest that BDNF/miR-195/Bcl-2 axis may be beneficial for limiting myocardial ischemic injury.

Background and Purpose Atrial metabolic remodelling is critical for the process of atrial fibrillation (AF). The PPAR-α/sirtuin 1 /PPAR co-activator α (PGC-1α) pathway plays an important role in maintaining energy metabolism. However, the effect of the PPAR-α agonist fenofibrate on AF is unclear. Therefore, the aim of this study was to determine the effect of fenofibrate on atrial metabolic remodelling in AF and explore its possible mechanisms of action. Experimental Approach The expression of metabolic proteins was examined in the left atria of AF patients. Thirty-two rabbits were divided into sham, AF (pacing with 600 beats·min−1 for 1 week), fenofibrate treated (pretreated with fenofibrate before pacing) and fenofibrate alone treated (for 2 weeks) groups. HL-1 cells were subjected to rapid pacing in the presence or absence of fenofibrate, the PPAR-α antagonist GW6471 or sirtuin 1-specific inhibitor EX527. Metabolic factors, circulating biochemical metabolites, atrial electrophysiology, adenine nucleotide levels and accumulation of glycogen and lipid droplets were assessed. Key Results The PPAR-α/sirtuin 1/PGC-1α pathway was significantly inhibited in AF patients and in the rabbit/HL-1 cell models, resulting in a reduction of key downstream metabolic factors; this effect was significantly restored by fenofibrate. Fenofibrate prevented the alterations in circulating biochemical metabolites, reduced the level of adenine nucleotides and accumulation of glycogen and lipid droplets, reversed the shortened atrial effective refractory period and increased risk of AF. Conclusion and Implications Fenofibrate inhibited atrial metabolic remodelling in AF by regulating the PPAR-α/sirtuin 1/PGC-1α pathway. The present study may provide a novel therapeutic strategy for AF.

Brain-derived neurotrophic factor (BDNF)/tropomyosin-related receptor kinase B (TrkB) pathway has been revealed as a novel therapeutic target for several neurological diseases. Recently, small-molecule TrkB agonist 7,8-dihydroxyflavone (7,8-DHF) has received considerable attention as a novel potential candidate for the treatment of various BDNF-implicated human disorders. However, its roles in cardiac diseases are not fully understood. Here, the present study aimed to clarify the effects and mechanisms of 7,8-DHF on doxorubicin (Dox)-induced cardiotoxicity. Kunming mice and H9c2 cells were employed to investigate the functional role of 7,8-DHF both in vivo and in vitro. 7,8-DHF markedly increased cell viability and reduced cell death of Dox-treated cells. Meanwhile, 7,8-DHF significantly increased mitochondrial respiration, membrane potential, and optic atrophy 1 (OPA1) protein expression. 7,8-DHF improved cardiac function and attenuated cardiac injury in Dox mice model. Expression of AMP-activated protein kinase (AMPK) and signal transducers and activators of transcription 3 (STAT3) was restored by 7,8-DHF. Furthermore, the protective role of 7,8-DHF was abolished by ANA-12 (a specific antagonist of TrkB). In elucidating the molecular mechanism, the phosphorylation of Akt was significantly increased while extracellular regulated protein kinase (ERK) was decreased after 7,8-DHF treatment. The regulatory effects of 7,8-DHF on STAT3 and AMPK was reversed by Akt inhibitor. In summary, 7,8-DHF attenuated Dox-induced cardiotoxicity by activating Akt and increasing mitochondrial oxidative phosphorylation and thereby regulating STAT3, AMPK, and ERK signals. The present study enhanced current understanding of TrkB receptor in the cardiovascular system and provided a novel target for prevention and treatment of heart diseases.

Background: Brain-derived neurotrophic factor (BDNF) is associated with coronary artery diseases. However, its role and mechanism in myocardial infarction (MI) is not fully understood. Methods: Wistar rat and Kunming mouse model of MI were induced by the ligation of left coronary artery. Blood samples were collected from MI rats and patients. Plasma BDNF level, protein expression of BDNF, tropomyosin-related kinase B (TrkB) and its downstream transient receptor potential canonical (TRPC)3/6 channels were examined by enzyme-linked immunosorbent assay and Western blot. Infarct size, cardiac function and cardiomyocyte apoptosis were measured after intra-myocardium injection with recombinant human BDNF. Protective role of BDNF against cardiomyocyte apoptosis was confirmed by BDNF scavenger TrkB-Fc. The regulation of TRPC3/6 channels by BDNF was validated by pretreating with TRPC blocker (2-Aminoethyl diphenylborinate, 2-APB) and TRPC3/6 siRNAs. Results: Circulating BDNF was significantly enhanced in MI rats and patients. Protein expression of BDNF, TrkB and TRPC3/6 channels were upregulated in MI. 3 days post-MI, BDNF treatment markedly reduced the infarct size and serum lactate dehydrogenase activity. Meanwhile, echocardiography indicated that BDNF significantly improved cardiac function of MI mice. Furthermore, BDNF markedly inhibited cardiomyocyte apoptosis by upregulating Bcl-2 expression and downregulating caspase-3 expression and activity in ischemic myocardium. In neonatal rat ventricular myocytes, cell viability was dramatically increased by BDNF in hypoxia, which was restored by TrkB-Fc. Furthermore, protective role of BDNF against hypoxia-induced apoptosis was reversed by 2-APB and TRPC3/6 siRNAs. Conclusion: BDNF/TrkB alleviated cardiac ischemic injury and inhibited cardiomyocytes apoptosis by regulating TRPC3/6 channels, which provides a novel potential therapeutic candidate for MI.

Recent studies have revealed the cytoprotective roles of microRNAs (miRNAs) miR-21 and miR-146a against ischemic cardiac injuries. While these studies investigated each of these miRNAs as an independent individual factor, our previous study has suggested the possible interaction between these two miRNAs. The present study was designed to investigate this possibility by evaluating the effects of miR-21 and miR-146a combination on cardiac ischemic injuries and the underlying mechanisms. MiR-21 and miR-146a synergistically decreased apoptosis under ischemia/hypoxic conditions in cardiomyocytes compared with either miR-21 or miR-146a alone. Mice coinjected with agomiR-21 and agomiR-146a had decreased infarct size, increased ejection fraction (EF), and fractional shortening (FS). These effects were greater than those induced by either of the two agomiRs. Furthermore, greater decreases in p38 mitogen-associated protein kinase phosphorylation (p-p38 MAPK) were observed with miR-21: miR-146a combination as compared to application of either of the miRNAs. These data suggest that combination of miR-21 and miR-146a has a greater protective effect against cardiac ischemia/hypoxia-induced apoptosis as compared to these miRNAs applied individually. This synergistic action is mediated by enhanced potency of inhibition of cardiomyocyte apoptosis by the miR-21—PTEN/AKT—p-p38—caspase-3 and miR-146a—TRAF6—p-p38—caspase-3 signal pathways.

The aim of this study was to assess the influence of the Panax notoginseng saponins (PNS) on the activities of the drug-metabolizing enzymes cytochrome P450 (CYP450) 1A2, 2 C9, 2D6 and 3A4 in rats. The activities of CYP1A2, 2 C9, 2D6 and 3A4 were measured using specific probe drugs. After pretreatment for 1 week with PNS or physiological saline (control group), probe drugs caffeine (10 mg/kg; CYP1A2 activity), tolbutamide (15 mg/kg; CYP2C9 activity), metoprolol (20 mg/kg; CYP2D6 activity) and dapsone (10 mg/kg; CYP3A4 activity) were administered to rats by intraperitoneal injection. The blood was then collected at different times for ultra performance liquid chromatography/tandem mass spectrometry (UPLC-MS/MS) analysis. The data showed that PNS exhibited an induction effect on CYP1A2 by decreasing caffeine Cmax (36.3%, p

It has been well documented that ion channels and intercellular gap junctional proteins participated in the pathophysiological processes of myocardial infarction (MI) which resulted in lethal arrhythmias and sudden cardiac death. miRNA expression is dynamically regulated during MI and altered miRNA expression can induce deregulation of ion channel genes at the post-transcriptional level. We conducted a rationally designed bioinformatics analysis combined with experimental approaches to screen key therapeutic members in the IUPHAR database and Wikipedia, a whole genome protein interaction network was established here and comprehensive topological assessment was applied to confirm the individual network status and to reflect their biological significance. Meanwhile, the number of validated and confidently predicted miRNAs regulating each gene encoding ion channel or gap junction protein was counted. miRNA analysis indicated that connexin 43 was under more intensive miRNA regulation compared with the other ion channel and gap junction proteins. Furthermore, the topological network analysis highlighted the important role of connexin 43 in MI and also identified the important biological roles of TRPV4, SCN5A, CACNA1C and TRPC6. The abnormal expression of TRPC6 was experimentally validated in 1 month MI model of rat, which implied its potential therapeutic target for MI. Our work suggested that network systems approach could gain valuable insight into the pathological mechanism of MI which has not been uncovered by previous experimental studies.

Background M3 muscarinic acetylcholine receptor (M3-mAChR) is stably expressed in the myocardium, but its pathophysiological role remains largely undefined. This study aimed to investigate the role of M3-mAChR in cardiac hypertrophy induced by angiotensin II (Ang II) and elucidate the underlying mechanisms. Methods Cardiac-specific M3-mAChR overexpression transgenic (TG) mice and rat H9c2 cardiomyoblasts with ectopic expression of M3-mAChR were established. Models of cardiac hypertrophy were induced by transverse aortic constriction (TAC) or Ang II infusion in the mice in vivo, and by isoproterenol (ISO) or Ang II treatment of H9c2 cells in vitro. Cardiac hypertrophy was evaluated by electrocardiography (ECG) measurement, hemodynamic measurement and histological analysis. mRNA and protein expression were detected by real-time RT-PCR and Western blot analysis. Results M3-mAChR was upregulated in hypertrophic heart, while M2-mAChR expression did not change significantly. M3-mAChR overexpression significantly attenuated the increased expression of atrial natriuretic peptide and β-myosin heavy chain induced by Ang II both in vivo and in vitro. In addition, M3-mAChR overexpression downregulated AT1 receptor expression and inhibited the activation of MAPK signaling in the heart. Conclusion The upregulation of M3-mAChR during myocardial hypertrophy could relieve the hypertrophic response provoked by Ang II, and the mechanism may involve the inhibition of MAPK signaling through the downregulation of AT1 receptor.

Background/Aims: Arsenic trioxide (As2O3) is a highly effective agent for treatment of acute promyelocytic leukemia (APL). However, consecutively administered As2O3 induces serious adverse cardiac effects, including long QT syndrome (LQTs) and even sudden cardiac death. Previous studies have shown that genistein (Gen) exerts anti-oxidant, anti-inflammatory, and anti-apoptotic effects. The present study aimed to explore the potential protective effects of Gen on As2O3-induced adverse cardiac effects, and to elucidate the underlying molecular mechanisms. Methods: A rat model of As2O3-induced QT prolongation was generated by intravenous injection with As2O3. Surface electrocardiogram (ECG) and hemodynamics were employed to assess the LQTs and cardiac function. Intracellular calcium concentration ([Ca2+]i) and mitochondrial membrane potential (Δψm) were measured by confocal microscopy, and cardiomyocytes apoptosis were assessed by TUNEL assay. Western blot was applied to determine protein levels. Results: We found for the first time that treatment with Gen significantly reversed LQTs and dose-dependently improved As2O3-induced impairment of cardiac function. As2O3 elevated [Ca2+]i and Gen mitigated this effect. Meanwhile, Gen significantly reversed As2O3-mediated cardiomyocytes apoptosis. Furthermore, Gen dose-dependently inhibited the phosphorylated JNK and p38-MAPK (pp38-MAPK), and blocked Δψm collapse, and further decreased cleaved caspase-3. Conclusion: Gen protects against the adverse cardiac effects of As2O3 partly by mitigating cardiomyocytes apoptosis induced by As2O3 through attenuating intracellular calcium overload and downregulating protein expression of p-JNK and pp38-MAPK to ameliorate the damage of Δψm leading to suppression of caspase-3 activation. Gen might be used as an adjunction therapy in APL patients receiving As2O3 treatment to avoid, at least to minimize, the adverse cardiac effects of As2O3.

The mechanisms of myocardial dysfunction and calcium handling disturbance underlying cerebral ischemia remain obscure. Here we for the first time report that acute cerebral ischemia significantly increased left ventricular end diastolic pressure (LVEDP), but decreased +dP/dt, -dP/dt, and left ventricular systolic pressure (LVSP). Significant increase in either the resting or KCl-induced [Ca2+](i)in ventricular myocytes was also detected by scanning confocal microscopy at 2 and 24 hours after cerebral ischemia. Verapamil as a blocker of I(Ca,L), ryanodine as a specific inhibitor of RyR, thapsigargin as a highly specific inhibitor of sarco(endo)plasmic reticulum Ca(2+)-ATPase 2a (SERCA2a) and SEA0400 as a selective NCX inhibitor changed the area under the curve of averaged ratio of fluorescence (FI/F(0)I) induced by KCl. Cardiac expression of Ca(v)1.2 was significantly up-regulated at 2 and 24 hours after cerebral ischemia, whereas cardiac expression of SERCA2a and Na(+)-Ca(2+) exchanger (NCX) was significantly down-regulated at the same time period after cerebral ischemia. Cardiac expression of phospholamban (PLB) was significantly elevated at 2 hours after cerebral ischemia but was restored to about normal level at 24 hours after injury. These data suggest that acute cerebral ischemia may specifically disturb cardiac function and calcium homeostasis, which are related to increase of Ca(v)1.2 and decrease of through up-regulating Ca(v)1.2 and PLB, down-regulating SERCA2a and NCX, subsequently leading to Ca2+ overload by the enhancement of Ca2+ influx and inhibition of intracellular Ca2+ extrusion and cerebral ischemia-induced myocardial dysfunction.

The iron homeostasis plays an important role in cardiac function. To understand how it acts in diabetic and ischemic myocardial injury, we studied the myocardial iron metabolism in diabetic and myocardial ischemic rats. Diabetic rats were induced by intraperitoneal injection of streptozocin (STZ) after intragastric administration of a high-fat diet while the ischemic rat hearts were subjected to coronary artery ligation for 0.5, 1, 6, 12 or 24 h, respectively. In STZ-induced diabetic rats, the contents of serum and myocardial iron were found elevated obviously accompany with the decrease of hepatic iron determined by the flame emission atomic absorption spectroscopy. The levels of superoxide dismutase (SOD), malonaldehyde (MDA) and serum ferritin were increased in diabetic rats. Moreover, protein level of divalent metal transporter 1 (DMT1) was decreased while that for transferrin receptor (TfR) and metal transporter protein 1 (MTP1) was increased. In contrast, no alteration of iron concentration was observed in the ischemic rats. The expression of DMT1, TfR and MTP1 has not changed after infraction. The findings suggested that diabetes mellitus (DM) induced the iron overload in the myocardium, at least in part by up-regulation of TfR. Meanwhile, down-regulation of DMT1 and up-regulation of MTP1 were induced to alleviate the excessive iron in the myocardium. However, myocardial infraction (MI) has not broken the balance of myocardial iron. In conclusion, the iron homeostasis reacts differently in DM and MI.

mesenchymal stem cells Jing Zhao , Pengzhou Hang , Yue Li a,⁎ a Department of Cardiology, the First Affiliated Hospital, Harbin Medical University, (Key Laboratory of Cardiac Diseases and Heart Failure, Harbin Medical University), Harbin, 150001, Heilongjiang Province, China b Institute of Clinical Pharmacy, the Second Affiliated Hospital, Harbin Medical University, (Key Laboratory of Drug Research, Harbin Medical University, Heilongjiang Higher Education Institutions), Harbin, 150086, Heilongjiang Province, China