Ascorbic acid prevents acute myocardial infarction induced by isoproterenol in rats: role of inducible nitric oxide synthase production

Kaempferol alleviates myocardial ischemia injury by reducing oxidative stress via the HDAC3-mediated Nrf2 signaling pathway

INTRODUCTION

Kaempferol (KAE) is a flavonoid found in various plants. Recent studies showed that high dietary intake of KAE was associated with a lower risk of myocardial infarction; however, the cardioprotective mechanism of KAE remains unknown.

OBJECTIVES

To determine the effect of KAE on cardiac injury in isoproterenol (ISO)-induced rats and cobalt chloride (CoCl2)-treated cardiomyocytes, and the underlying mechanisms.

METHODS

Male rats were pretreated with different doses of KAE for 14 days, and then injected with ISO to induce myocardial ischemia injury. We also established a model of myocardial cell injury using rat H9c2 cardiomyocytes stimulated with CoCl2.

RESULTS

We found that KAE pretreatment significantly alleviated myocardial injury and improved cardiac function in ISO-injected rats. In addition, KAE reduced oxidative stress in rats with myocardial ischemia by decreasing malondialdehyde concentration and increasing superoxide dismutase activity, and protection of the myocardial mitochondrial structure. KAE also attenuated CoCl2-induced injuryof H9c2 cardiomyocytes via suppression ofoxidative stress. With regard to the mechanism, we found that KAE down-regulated HDAC3 expression and up-regulated Nrf2 expression in ISO-induced rats and CoCl2-stimulated cardiomyocytes. Incubation of cardiomyocytes with HDAC3-selective inhibitor RGFP966 augmented the protective effect of KAE and reduced oxidative stress. By contrast, HDAC3 overexpression by adenovirus attenuated the effect of KAE on oxidative stress compared with KAE treatment group. HDAC3 also regulated Nrf2 expression in the cardiomyocytes with RGFP966 or an adenovirus overexpressing HDAC3; but Nrf2 inhibition reduced the effect of KAE on ROS generation in CoCl2-induced cardiomyocytes. Immunoprecipitation assay showed that HDAC3 interacted with Nrf2 in cardiomyocytes. Further studies found that KAE increased the acetylation level of Nrf2, while HDAC3 overexpression decreased the acetylation of Nrf2 compared with KAE treatment group.

CONCLUSION

Our data show that KAE ameliorates cardiac injury by reducing oxidative stress via the HDAC3-mediated Nrf2 signaling pathway in cardiomyocytes.

Puerarin attenuates isoproterenol‑induced myocardial hypertrophy via inhibition of the Wnt/β‑catenin signaling pathway

Myocardial hypertrophy (MH) is an independent risk factor for cardiovascular disease, which in turn lead to arrhythmia or heart failure. Therefore, attention must be paid to formulation of therapeutic strategies for MH. Puerarin is a key bioactive ingredient isolated from Pueraria genera of plants that is beneficial for the treatment of MH. However, its molecular mechanism of action has not been fully determined. In the present study, 40 µM puerarin was demonstrated to be a safe dose for human AC16 cells using Cell Counting Kit‑8 assay. The protective effects of puerarin against MH were demonstrated in AC16 cells stimulated with isoproterenol (ISO). These effects were characterized by a significant decrease in surface area of cells (assessed using fluorescence staining) and mRNA and protein expression levels of MH‑associated biomarkers, including atrial and brain natriuretic peptide, assessed using reverse transcription‑quantitative PCR and western blotting, as well as β‑myosin heavy chain mRNA expression levels. Mechanistically, western blotting demonstrated that puerarin inhibited activation of the Wnt signaling pathway. Puerarin also significantly decreased phosphorylation of p65; this was mediated via crosstalk between the Wnt and NF‑κB signaling pathways. An inhibitor (Dickkopf‑1) and activator (IM‑12) of the Wnt signaling pathway were used to demonstrate that puerarin‑mediated effects alleviated ISO‑induced MH via the Wnt signaling pathway. The results of the present study demonstrated that puerarin pre‑treatment may be a potential therapeutic strategy for preventing ISO‑induced MH and managing MH in the future.

Stable Gastric Pentadecapeptide BPC 157 May Counteract Myocardial Infarction Induced by Isoprenaline in Rats

We revealed that the stable gastric pentadecapeptide BPC 157, a useful peptide therapy against isoprenaline myocardial infarction, as well as against isoprenaline myocardial reinfarction, may follow the counteraction of the recently described occlusion-like syndrome, induced peripherally and centrally, which was described for the first time in isoprenaline-treated rats. BPC 157 (10 ng/kg, 10 µg/kg i.p.), L-NAME (5 mg/kg i.p.), and L-arginine (200 mg/kg i.p.) were given alone or together at (i) 30 min before or, alternatively, (ii) at 5 min after isoprenaline (75 or 150 mg/kg s.c.). At 30 min after isoprenaline 75 mg/kg s.c., we noted an early multiorgan failure (brain, heart, lung, liver, kidney and gastrointestinal lesions), thrombosis, intracranial (superior sagittal sinus) hypertension, portal and caval hypertension, and aortal hypotension, in its full presentation (or attenuated by BPC 157 therapy (given at 5 min after isoprenaline) via activation of the azygos vein). Further, we studied isoprenaline (75 or 150 mg/kg s.c.) myocardial infarction (1 challenge) and reinfarction (isoprenaline at 0 h and 24 h, 2 challenges) in rats (assessed at the end of the subsequent 24 h period). BPC 157 reduced levels of all necrosis markers, CK, CK-MB, LDH, and cTnT, and attenuated gross (no visible infarcted area) and histological damage, ECG (no ST-T ischemic changes), and echocardiography (preservation of systolic left ventricular function) damage induced by isoprenaline. Its effect was associated with a significant decrease in oxidative stress parameters and likely maintained NO system function, providing that BPC 157 interacted with eNOS and COX2 gene expression in a particular way and counteracted the noxious effect of the NOS-blocker, L-NAME.

β-Caryophyllene inhibits Fas- receptor and caspase-mediated apoptosis signaling pathway and endothelial dysfunction in experimental myocardial infarction

We planned to appraise the effects of β-caryophyllene on Fas- receptor and caspase-mediated apoptosis signaling pathway and endothelial dysfunction in rats infarcted with isoproterenol. Rats were induced myocardial infarction by using isoproterenol (100 mg/kg body weight [b.w]). Serum creatine kinase-MB, serum cardiac troponin-T, heart weight, heart rate, and heart lipid peroxidation were greatly (p < 0.05) augmented, while heart enzymatic antioxidants and plasma nonenzymatic antioxidants were greatly (p < 0.05) lessened in isoproterenol-treated rats. Reverse transcription-polymerase chain reaction study revealed augmented expressions of Fas-receptor and caspases 8, 9, and 3 genes in myocardial infarcted rats. Furthermore, iNOS protein expression was amplified and eNOS protein was lessened in the myocardial infarcted heart. Three weeks pre- and cotreatment with β-caryophyllene (20 mg/kg b.w) greatly (p < 0.05) protected isoproterenol-treated rats against these altered structural, biochemical, molecular, and immunohistochemical parameters, by its anti-cardiac hypertrophic, anti-tachycardial, antioxidant, anti-apoptotic, and anti-endothelial dysfunction effects. In conclusion, these findings projected the use of β-caryophyllene for the therapy of human myocardial infarction after clinical trials.

Mitochondrial Dysfunction in Cardiorenal Syndrome 3: Renocardiac Effect of Vitamin C

Cardiorenal syndrome (CRS) is a pathological link between the kidneys and heart, in which an insult in a kidney or heart leads the other organ to incur damage. CRS is classified into five subtypes, and type 3 (CRS3) is characterized by acute kidney injury as a precursor to subsequent cardiovascular changes. Mitochondrial dysfunction and oxidative and nitrosative stress have been reported in the pathophysiology of CRS3. It is known that vitamin C, an antioxidant, has proven protective capacity for cardiac, renal, and vascular endothelial tissues. Therefore, the present study aimed to assess whether vitamin C provides protection to heart and the kidneys in an in vivo CRS3 model. The unilateral renal ischemia and reperfusion (IR) protocol was performed for 60 min in the left kidney of adult mice, with and without vitamin C treatment, immediately after IR or 15 days after IR. Kidneys and hearts were subsequently collected, and the following analyses were conducted: renal morphometric evaluation, serum urea and creatinine levels, high-resolution respirometry, amperometry technique for NO measurement, gene expression of mitochondrial dynamic markers, and NOS. The analyses showed that the left kidney weight was reduced, urea and creatinine levels were increased, mitochondrial oxygen consumption was reduced, NO levels were elevated, and Mfn2 expression was reduced after 15 days of IR compared to the sham group. Oxygen consumption and NO levels in the heart were also reduced. The treatment with vitamin C preserved the left kidney weight, restored renal function, reduced NO levels, decreased iNOS expression, elevated constitutive NOS isoforms, and improved oxygen consumption. In the heart, oxygen consumption and NO levels were improved after vitamin C treatment, whereas the three NOS isoforms were overexpressed. These data indicate that vitamin C provides protection to the kidneys and some beneficial effects to the heart after IR, indicating it may be a preventive approach against cardiorenal insults.

Effect of chronic alcohol consumption on myocardial apoptosis in the rat model of isoproterenol-induced myocardial injury and investigation on the cardioprotective role of calpain inhibitor 1

We investigated the presence of myocardial apoptosis on isoproterenol (ISO)-induced myocardial injury (MI) after long-term high dose alcohol consumption and examined the antiapoptotic role of calpain inhibitor 1. Male Wistar Albino rats (n = 108) were divided into six groups: Control, alcohol (ethanol was given during 30 days for chronic alcohol consumption), MI (150 mg/kg ISO injection at last two days of alcohol consumption), alcohol + MI, alcohol + MI + calpain inhibitor 1 (10 mg/kg inhibitor was injected at 15 min before ISO injections) and Dimethyl Sulfoxide (DMSO) groups. Biochemical, histological, and morphometric methods determined apoptosis levels in the heart tissue of rats. Cytochrome c, caspase 3, and calpain levels were significantly high in alcohol, MI, and alcohol + MI groups. In contrast, mitochondrial cardiolipin content was found to be low in alcohol, MI, and alcohol + MI groups. These parameters were close to the control group in the therapy group. Histological and morphometric data have supported biochemical results. As a result of our biochemical data, myocardial apoptosis was seen in the alcohol, MI, and especially alcohol after MI groups. Calpain inhibitor 1 reduced apoptotic cell death and prevented myocardial tissue injury in these groups. The efficiency of calpain inhibitor was very marked in MI after long-term high dose alcohol consumption.

The protective effect of piperine against isoproterenol-induced inflammation in experimental models of myocardial toxicity

Myocardial infarction (MI) eventually exacerbates inflammatory response due to the release of inflammatory and pro-inflammatory factors. The aim of this study is to explore the protective efficacy of piperine supplementation against the inflammatory response in isoproterenol (ISO)-induced MI. Masson Trichome staining was executed to determine myocardial tissue architecture. Immunohistochemistry was performed for IL-6, TNF-α. RT-PCR studies were performed to ascertain the gene expression of IL-6, TNF-α, iNOS, eNOS, MMP-2, MMP-9, and collagen-III. Western blotting was performed to determine expression of HIF-1α, VEGF, Nrf-2, NF-ƙB, Cox-2, p-38, phospho-p38, ERK-1/2, phospho-ERK-1/2, and collagen-I. HIF-1α, VEGF, and iNOS expression were significantly upregulated with concomitant decline in eNOS expression in the heart myocardial tissue of rats received ISO alone whereas piperine pretreatment prevented these changes in ISO administered rats. Current results revealed ROS-mediated activation of MAPKs, namely, p-p38, p-ERK1/2 in the heart tissue of ISO administered group. Piperine pretreatment significantly prevented these changes in ISO treated group. NF-κB is involved in the modulation of gene expressions responsible for tissue repair. ISO-induced NF-κB-p65 expression was significantly reduced in the group pretreated with piperine and mitigated extent of myocardial inflammation. A significant increase in cardiac fibrosis upon ISO treatment was reported due to the increased hydroxyproline content, MMP-2 & 9 and upregulation of collagen-I protein compared to control group. All these cardiac hypertrophy markers were decreased in 'piperine pretreated ISO administered group' compared to group received ISO injection. Current findings concluded that piperine as a nutritional intervention could prevent inflammation of myocardium in ISO-induced MI.

M3, a 1,4-Dihydropyridine Derivative and Mixed L-/T-Type Calcium Channel Blocker, Attenuates Isoproterenol-Induced Toxicity in Male Wistar Rats

Recent evidence indicates that Ca²⁺ dysregulation is involved in the pathogenesis of isoproterenol (ISP)-induced biochemical toxicity and associated oxidative stress. In this study, we investigated the chemopreventive benefit of M3, a 1,4-dihydropyridine calcium channel blocker, against ISP-induced toxicity in male Wistar rats. Adult rats were divided into eight groups of six rats/group. Groups 1-5 received normal saline (control, 10 mL/kg/day, p.o.), ISP (85 mg/kg/day, s.c.), M3 lower dose (M3LD, 5 mg/kg, p.o.), M3 upper dose (M3UD, 20 mg/kg/day, p.o.), and Nifedipine (NFD, 20 mg/kg/day, p.o.), respectively. Others (groups 6-8) were pretreated with either M3LD, M3UD or NFD one hour before ISP administration. All rats were sacrificed 24 h after the last administration and changes in biochemical, hematological, and antioxidant parameters were assessed. Histologic examination of the heart, liver and kidney was also conducted. ISP elevated (p < 0.05) Ca²⁺, alanine aminotransferase, lactate dehydrogenase, triglycerides, and low-density lipoprotein levels when compared with control. Similarly, ISP increased levels of markers of renal function (p < 0.01), C-reactive protein (148.1%) and myocardial malondialdehyde (MDA, 88.7%) and tumor necrosis factor-alpha (109.2%). Platelet level was reduced (p < 0.05) in the ISP-intoxicated control rats. M3 exhibited antioxidant property, reduced levels of triglycerides, MDA and improved biochemical and hematological alterations associated with ISP toxicity. M3, however, was not effective in restoring histological changes that characterized ISP toxicity at the doses used. M3 offers chemopreventive benefits against ISP toxicity possibly through L-/T-type calcium channels blockade and modulatory actions on biochemical and antioxidant homeostasis.

Remifentanil attenuates cardiac dysfunction, lipid peroxidation and immune disorder in rats with isoproterenol-induced myocardial injury via JNK/NF-KB p65 inhibition

Background

Myocardial injury caused by myocardial ischemia (MI) is still a severe condition that can result in apoptosis, oxidative stress, and inflammation. Remifentanil is a selective, ultra-short-acting, µ-opioid receptor agonist opioid. It can improve sinusoidal heart rate patterns in the fetus, for bupivacaine-induced cardiotoxicity, and with lipopolysaccharide (LPS)-induced cardiomyocytes injuries. This study aimed to explore the cardioprotective effects of remifentanil in MI model rats.

Methods

Sprague Dawley (SD) rats were split into five groups at random, including a control group, Isop group, low-dose remifentanil treatment group (10 µg/kg), medium-dose remifentanil treatment group (20 µg/kg), and a high-dose remifentanil treatment group (40 µg/kg). The MI model was achieved by subcutaneously injecting rats with isoproterenol (85 mg/kg) for two consecutive days. With the expression of apoptotic molecules, myocardial systolic function index, inflammation, antioxidant enzymes, and the myocardial enzyme taken into account, the data was analyzed.

Results

After treatment with remifentanil, the left ventricular wall thickness (LVWT), left ventricular end-systolic volume (LVESV), left ventricular ejection fraction (LVEF), fraction shortening (FS), and heart rate (HR) were significantly increased in comparison with the Isop group. Creatine kinase-MB (CK-MB), Mb, and cTnl expressions were decreased. Meanwhile, the levels of cleaved caspase-3 and caspase-9 were decreased. Remarkably, the levels of reactive oxidative species (ROS), malondialdehyde (MDA), and lactate dehydrogenase (LDH) were observed to be repressed, while the levels of superoxide dismutase (SOD) was significantly increased. More importantly, the levels of tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, IL-6, and interferon (IFN)-γ were decreased.

Conclusions

Remifentanil has significant potential as a therapeutic intervention strategy for ameliorating myocardial injury after MI and these findings provide the rationale for further clinical studies.

Sacubitril and valsartan protect from experimental myocardial infarction by ameliorating oxidative damage in Wistar rats

BACKGROUND

Sacubitril (SAC), a neprilysin inhibitor prevent degradation of neprilysin and activate cGMP signaling pathways leading to rise in blood volume concurrent to blood pressure by means of vasoactive peptides, adrenomedullin, and bradykinin.

OBJECTIVE

The aim of this study was to evaluate the anti-ischemic effects of SAC through inhibiting neprilysin in isoproterenol (ISO) induced myocardial infarction (MI) in Wistar albino rats. ISO (85 mg/kg) was injected subcutaneously at the end of 14 days pre-treatment with SAC and valsartan (VAL).

RESULT

Biochemical investigation revealed that SAC along with VAL significantly prevented the antioxidant enzymes (SOD, Catalase, GR, GPx, GST, and GSH) degradation and malondialdehyde (MDA) induced by ISO intoxication in Wistar rats. Along with this, cardiac biomarkers (LDH, CK-MB, ALT, AST, and ALP) were also significantly ameliorated by SACand VAL in ISO-treated rats. Concurrently, decreased infarction area (IA)and marked reduction in myofibril damage by SACand VAL further supported its protective benefits in MI.

CONCLUSION

Taken together, the results suggest that inhibition of enzyme neprilysin alleviated the ISO induces myocardial damage mediated by its strong antioxidant potential.

Polyphenolic Compounds, Antioxidant, and Cardioprotective Effects of Pomace Extracts from Fetească Neagră Cultivar

Grape pomace is a potential source of natural antioxidant agents. Phenolic compounds and antioxidant and cardioprotective properties of fresh and fermented pomace extracts obtained from Vitis vinifera L. red variety Fetească neagră grown in Romania in 2015 were investigated. Grape pomace extracts total phenolic index, total tannins, total anthocyanins, proanthocyanidins, flavan-3-ol monomers, stilbenes, and DPPH free radical scavenger were measured. The effect of a seven-day pretreatment with grape pomace extracts on the isoprenaline-induced infarct-like lesion in rats was assessed by ECG monitoring, serum levels of creatine kinase, aspartate transaminase, and alanine transaminase. Total serum oxidative status, total antioxidant response, oxidative stress index, malondialdehyde, total thiols, and nitric oxide have been also assessed. Higher phenolic content and antioxidant activity were found in fermented pomace extracts when compared to fresh pomace extracts. Pretreatment with grape pomace extracts significantly improved cardiac and oxidative stress parameters. In conclusion, Fetească neagră pomace extracts had a good in vitro antioxidant activity due to an important phenolic content. In vivo, the extracts had cardioprotective effects against isoprenaline-induced infarct-like lesion by reducing oxidative stress, fresh pomace extracts having a better effect.

Effects of dabigatran regulates no‑reflow phenomenon in acute myocardial infarction mice through anti‑inflammatory and anti‑oxidative activities and connective tissue growth factor expression

Pradaxa is a novel oral anticoagulant, which was originally used to prevent thrombosis following joint replacement surgery. The aim of the current study was to investigate the effect dabigatran on acute myocardial infarction through regulating no‑reflow phenomenon and oxidative stress, neutrophil intraplaque infiltration and apoptosis. In the present study, dabigatran significantly inhibited the infarct size, increased arterial pressure and reduced no‑reflow phenomenon in acute myocardial infarction (AMI) vehicle rabbits. Treatment with dabigatran significantly inhibited the P65 of nuclear factor κB, tumor necrosis factor α, interleukin (IL)‑1β and IL‑6 activities and significantly enhanced the catalase and superoxide dismutase activities in the AMI rabbits. In addition, dabigatran significantly suppressed inducible nitric oxide synthase (iNOS), collagen I, transforming growth factor β1 (TGF‑β1), α‑smooth muscle actin (α‑SMA) and connective tissue growth factor (CTGF) protein expression in AMI rabbits. Taken together, these results suggest that the effects of dabigatran inhibit no‑reflow phenomenon, infarct size and enhance arterial pressure in AMI through anti‑inflammatory and anti‑oxidative activity, and regulating iNOS, collagen I, TGF‑β1, α‑SMA and CTGF protein expression in AMI rabbits.

Combined supplementation of ascorbic acid and thyroid hormone T3 affects tenocyte proliferation. The effect of ascorbic acid in the production of nitric oxide

BACKGROUND

Tissue engineering is now increasingly focusing on cell-based treatments as promising tools to improve tendon repair. However, many crucial aspects of tendon biology remain to be understood before adopting the best experimental approach for cell-tissue engineering.

METHODS

The role played by Ascorbic Acid (AA) alone and in combination with thyroid hormone T₃ in the viability and proliferation of primary human tendon-derived cells was investigated. Human tenocyte viability was detected by Trypan blue exclusion test and cellular proliferation rate was evaluated by CFSE CellTrace™. In addition, the potential role of the AA in the production of Nitric Oxide (NO) was also examined.

RESULTS

In this in vitro model, an increase in tenocyte proliferation rate was observed as a consequence of progressively increased concentrations of AA (from 10 to 50 µg/ml). The addition of the T₃ hormone to the culture further increased tenocyte proliferation rate. In detail, the most evident effect on cellular growth was achieved using the combined supplementation of 50 µg/ml AA and 10^-7 M T₃.

CONCLUSION

We showed that the highest concentration of AA (100 and 500 µg/ml) caused cytotoxicity to human tenocytes. Moreover, it was shown that AA reduces NO synthesis. These results show that AA is a cell proliferation inducer that triggers tenocyte growth, while it reduces NO synthesis.

Antioxidant and cardioprotective effects of Ilex cornuta on myocardial ischemia injury

Previous studies have indicated that the Ilex genus exhibits antioxidant, neuroprotective, hepatoprotective, and anti-inflammatory activities. However, the pharmacologic action and mechanisms of Ilex cornuta against cardiac diseases have not yet been explored. The present study was designed to investigate the antioxidant and cardioprotective effects of Ilex cornuta root with in vitro and in vivo models. The anti-oxidative effects of the extract of Ilex cornuta root (ICR) were measured by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging and MTT assays as well as immunoassay. Furthermore, a rat model of myocardial ischemia was established to investigate the cardioprotective effect of ICR in vivo. Eight compounds were isolated and identified from ICR and exhibited DPPH free-radical scavenging activities. They also could increase cell viability and inhibit morphological changes induced by H₂O₂ or Na₂S₂O₄ in H9c2 cardiomyocytes, followed by increasing the SOD activities and decreasing the MDA and ROS levels. In addition, it could suppress the apoptosis of cardiomyocytes. In the rat model of myocardial ischemia, ICR decreased myocardial infarct size and suppressed the activities of LDH and CK. Furthermore, ICR attenuated histopathological alterations of heart tissues and the MDA levels, while increasing SOD activities in serum. In conclusion, these results suggest that ICR has cardioprotective activity and could be developed as a new food supplement for the prevention of ischemic heart disease.

Ascorbic acid promotes extracellular matrix deposition while preserving valve interstitial cell quiescence within 3D hydrogel scaffolds

Current options for aortic valve replacements are non-viable and thus lack the ability to grow and remodel, which can be problematic for paediatric applications. Toward the development of living valve substitutes that can grow and remodel, porcine aortic valve interstitial cells (VICs) were isolated and encapsulated within proteolytically degradable and cell-adhesive poly(ethylene glycol) (PEG) hydrogels, in an effort to study their phenotypes and functions. The results showed that encapsulated VICs maintained high viability and proliferated within the hydrogels. The VICs actively remodelled the hydrogels via secretion of matrix metalloproteinase-2 (MMP-2) and deposition of new extracellular matrix (ECM) components, including collagens I and III. The soft hydrogels with compressive moduli of ~4.3 kPa quickly reverted VICs from an activated myofibroblastic phenotype to a quiescent, unactivated phenotype, evidenced by the loss of α-smooth muscle actin expression upon encapsulation. In an effort to promote VIC-mediated ECM production, ascorbic acid (AA) was supplemented in the medium to investigate its effects on VIC function and phenotype. AA treatment enhanced VIC spreading and proliferation, and inhibited apoptosis. AA treatment also promoted VIC-mediated ECM remodelling by increasing MMP-2 activity and depositing collagens I and III. AA treatment did not significantly influence the expression of α-smooth muscle actin (myofibroblast activation marker) and alkaline phosphatase (osteogenic differentiation marker). No calcification or nodule formation was observed within the cell-laden hydrogels, with or without AA treatment. These results suggest the potential of this system and the beneficial effect of AA in heart valve tissue engineering. Copyright © 2015 John Wiley & Sons, Ltd.

Mouse models for the study of postnatal cardiac hypertrophy

The main objective of this study was to create a postnatal model for cardiac hypertrophy (CH), in order to explain the mechanisms that are present in childhood cardiac hypertrophy. Five days after implantation, intraperitoneal (IP) isoproterenol (ISO) was injected for 7 days to pregnant female mice. The fetuses were obtained at 15, 17 and 19 dpc from both groups, also newborns (NB), neonates (7-15 days) and young adults (6 weeks of age). Histopathological exams were done on the hearts. Immunohistochemistry and western blot demonstrated GATA4 and PCNA protein expression, qPCR real time the mRNA of adrenergic receptors (α-AR and β-AR), alpha and beta myosins (α-MHC, β-MHC) and GATA4. After the administration of ISO, there was no change in the number of offsprings. We observed significant structural changes in the size of the offspring hearts. Morphometric analysis revealed an increase in the size of the left ventricular wall and interventricular septum (IVS). Histopathological analysis demonstrated loss of cellular compaction and presence of left ventricular small fibrous foci after birth. Adrenergic receptors might be responsible for changing a physiological into a pathological hypertrophy. However GATA4 seemed to be the determining factor in the pathology. A new animal model was established for the study of pathologic CH in early postnatal stages.

Cardioprotective effect of rhizomes of Acorus gramineus against isoproterenol-induced cardiac damage in pigs

The present study was designed to evaluate the cardioprotective potential of water extract of rhizomes of Acorus gramineus (AGR) against isoproterenol (ISO)-induced myocardial infarction. Male pigs were orally administered with 250 or 500 mg/kg of AGR or with vehicle for 9 days, with concurrent subcutaneous injections of ISO on the 8th and 9th day. Administration of AGR significantly ameliorated ISO-induced cardiac dysfunctions as evidenced by the ventricular ST-segment interval and R-amplitude as well as the left ventricle fractional shortening and ejection fraction. Additionally, administration of AGR significantly attenuated increased cardiac injury markers, such as cardiac troponin T, tumor necrosis factor-α, and myeloperoxidase activity, and cardiac marker enzymes, and prevented the depletion of antioxidant parameters. Malondialdehyde formation was also inhibited by AGR. Based on the results, it is concluded that AGR possesses significant cardioprotective potential and may serve as an adjunct in the treatment and prophylaxis of myocardial infarction.

Overexpression of inducible nitric oxide synthase impairs the survival of bone marrow stem cells transplanted into rat infarcted myocardium

AIMS

Inducible nitric oxide synthase (iNOS) over-expression is considered critical to the death of transplanted cells in infarcted myocardium. The present study was to investigate the effect of iNOS on the survival of transplanted bone marrow mesenchymal stem cells (BMSCs) in infarcted myocardium.

MAIN METHODS AND KEY FINDINGS

Male rat BMSCs were injected into the infarct region of female rat hearts at 1 hour (H1, group A), day 3 (D3, group B), and day 7 (D7, group C) after coronary artery ligation, and harvested on D7 after transplantation. Myocardial iNOS expression was significantly increased shortly after coronary ligation with its peak on D3, and returned to baseline at D7. The cell survival rates were 6.2%, 2.1%, and 8.3% in group A, B, and C, respectively, one week after transplantation as assessed by detecting the Y-chromosome sry sequence in the infarct region. There was no significant difference in the survival rates between D7 and week 6 after cell transplantation in group A. Treating the animals in group B with the selective iNOS inhibitor 1400 W significantly increased the survival rate (from 1.8% to 4.2%). Apoptosis level of the transplanted cells was also significantly reduced with 1400 W treatment in group B.

SIGNIFICANCE

BMSC transplantation on H1 and D7 after coronary ligation might be the optimal time for cell survival. The loss of transplanted BMSCs in the infarcted myocardium was partially due to increased apoptosis and iNOS overexpression. Selective iNOS inhibition early in myocardial infarction may increase the cell viability.

A pharmacokinetic and pharmacodynamic study of drug-drug interaction between ginsenoside Rg1, ginsenoside Rb1 and schizandrin after intravenous administration to rats

ETHNOPHARMACOLOGICAL RELEVANCE

Ginsenoside Rg1, ginsenoside Rb1 and schizandrin are main bioactive components from Panax ginseng and Schisandra chinensis. They have been found in many prescriptions of Traditional Chinese Medicines (TCM) and proven to be effective for prevention and treatment of cardiovascular disease. It is valuable to investigate their pharmacokinetic and pharmacodynamic behavior and potential synergistic effect for better drug development and clinical application.

MATERIALS AND METHODS

Pharmacokinetic and nitric oxide (NO) release pharmacodynamic drug-drug interactions of ginsenoside Rg1, ginsenoside Rb1 and schisandrin were studied after intravenous administration of each compound with the dose of 10 mg/kg and their mixture with the total dose of 10 mg/kg to isoproterenol (ISO)-induced myocardial ischemia rats. Drug concentrations in serum were determined using LC-MS method. Nitrite and nitrate (NOx(-)), the predominant oxidation product of NO in serum was used as an effective marker and quantitated by the method of high-performance liquid chromatography coupled with fluorescence detection (HPLC-FL). The main pharmacokinetic parameters of T(1/2β), MRT(0-∞), Vd, Cl, and AUC, and the main pharmacodynamic parameters of Cmax, Tmax and AUEC were calculated by non-compartment model.

RESULTS

The results indicated ginsenoside Rb1 and (or) schisandrin in mixture could significantly postpone the elimination of ginsenoside Rg1 in rat serum. Co-administration of three compounds markedly increased the systemic exposure level of each compound in vivo. Ginsenoside Rg1 and ginsenoside Rb1 had the effect of inducing real-time NO release in rats concentration dependently. Schisandrin had no effect of inducing real-time NO release in this study. The mixture of ginsenoside Rg1, Rb1 and schisandrin administration exhibited synergistic effect of inducing NO release in ISO treated rats.

CONCLUSIONS

The result obtained from this study suggested pharmacokinetic and pharmacodynamic drug-drug interactions between ginsenoside Rg1, Rb1 and schisandrin. The study provided valuable information for drug development and clinical application of TCM.

Protective effect of total phenylethanoid glycosides from Monochasma savatieri Franch on myocardial ischemia injury

The present study was designed to investigate the cardioprotective effect of total phenylethanoid glycosides from Monochasma savatieri Franch (TPG). The data showed that there were mainly four phenylethanoid glycosides isolated and identified from TPG. TPG significantly increased cells viability and inhibited morphological changes on H9c2 cardiomyocytes induced by H2O2 or Na2S2O4. In addition, TPG significantly decreased T-wave elevation and histopathological changes of heart tissues in myocardial infracted rats induced by isoproterenol. It also significantly reduced the infarct size induced by ligating the coronary artery in rats, increased the activities of antioxidative enzymes superoxide dismutase (SOD), the content of glutathione (GSH), and decreased the leakage of lactic dehydrogenase (LDH), the activities of creatine kinase (CK) and the content of maleic dialdehyde (MDA). In conclusion, these results suggested that TPG from Monochasma savatieri Franch might be developed as new natural medicine or food additives with effects of prevention of coronary artery disease due to its significant antioxidant activity.

Cardioprotective potential of Korean Red Ginseng extract on isoproterenol-induced cardiac injury in rats

The present study was designed to investigate the cardioprotective effects of Korean Red Ginseng extract (KRG) on isoproterenol (ISO)-induced cardiac injury in rats, particularly in regards to electrocardiographic changes, hemodynamics, cardiac function, serum cardiac enzymes, components of the myocardial antioxidant defense system, as well as inflammatory markers and histopathological changes in heart tissue. ISO (150 mg/kg, subcutaneous, two doses administered at 24-hour intervals) treatment induced significant decreases in P waves and QRS complexes (p<0.01), as well as a significant increase in ST segments. Moreover, ISO-treated rats exhibited decreases in left-ventricular systolic pressure, maximal rate of developed left ventricular pressure (+dP/dt_max) and minimal rate of developed left ventricular pressure (−dP/dt_max), in addition to significant increases in lactate dehydrogenase, aspartate transaminase, alanine transaminase and creatine kinase activity. Heart rate, however, was not significantly altered. And the activities of superoxide dismutase, catalase and glutathione peroxidase were decreased, whereas the activity of malondialdehyde was increased in the ISO-treated group. ISO-treated group also showed increased caspase-3 level, release of inflammatory markers and neutrophil infiltration in heart tissue. KRG pretreatment (250 and 500 mg/kg, respectively) significantly ameliorated almost all of the parameters of heart failure and myocardial injury induced by ISO. The protective effect of KRG on ISO-induced cardiac injury was further confirmed by histopathological study. In this regard, ISO treatment induced fewer morphological changes in rats pretreated with 250 or 500 mg/kg of KRG. Compared with the control group, all indexes in rats administered KRG (500 mg/kg) alone were unaltered (p>0.05). Our results suggest that KRG significantly protects against cardiac injury and ISO-induced cardiac infarction by bolstering antioxidant action in myocardial tissue.

Granulocyte colony-stimulating factor improves early remodeling in isoproterenol-induced cardiac injury in rats

BACKGROUND

Granulocyte colony-stimulating factor (G-CSF) has been used in some animal models and humans with well-established cardiovascular diseases. However, its effects in the initial stage of progressive non-ischemic heart failure are unknown.

METHODS

Wistar rats (260-300 g) were divided into three groups: control (without any intervention), ISO (150 mg/kg isoproterenol hydrochloride sc, once a day for two consecutive days), and ISO-GCSF (50 μg/kg/d G-CSF for 7 days beginning 24 h after the last administration of ISO). Echocardiography was performed at baseline and after 30 days of follow-up. Subsequently, animals were anesthetized for hemodynamic analysis. The left ventricle was removed for analysis of interstitial collagen deposition and cardiomyocyte hypertrophy.

RESULTS

Isoproterenol led to left ventricular dilation (control, 7.7 ± 0.14 mm; ISO, 8.7 ± 0.16 mm; ISO-GCSF 7.8 ± 0.09 mm; p < 0.05), myocardial fibrosis (control, 2.0 ± 0.18%; ISO, 9.1 ± 0.81%; ISO-GCSF 5.9 ± 0.58%; p < 0.05) and cardiomyocyte hypertrophy (control, 303 ± 10 μm(2); ISO, 356 ± 18 μm(2); ISO-GCSF 338 ± 11 μm(2); p < 0.05). However, G-CSF partially prevented collagen deposition and left ventricular enlargement, with a slight effect on hypertrophy. Characterizing a compensated stage of disease, hemodynamic analysis did not change.

CONCLUSION

G-CSF administered for 7 days was effective in preventing the onset of ventricular remodeling induced by high-dose isoproterenol with decreased collagen deposition and chamber preservation.

Naringenin more effectively inhibits inducible nitric oxide synthase and cyclooxygenase-2 expression in macrophages than in microglia

Macrophages and microglia are thought to account for initial disease progression in acute myocardial infarction and acute ischemic stroke. Before our study, the inhibitory effects of naringenin, a flavonoid, on lipopolysaccharide (LPS)-induced inflammation in macrophages and microglia have not been fully reported and compared. We hypothesized that naringenin can effectively inhibit LPS-induced inflammation of macrophages and microglia at different concentrations, the range of which is broader, with the lowest concentration more easily achieved in macrophages. In this study, we compared the anti-inflammatory effects of naringenin on LPS-stimulated RAW 274.6 macrophages and BV2 microglia and the suppression effects of naringenin and vitamin C (a well-known anti-inflammatory agent) on LPS-induced nitrite production. The results show that macrophages could maintain cell viability at higher naringenin concentrations and were more easily activated by LPS in comparison to microglia (200 vs 100 μmol/L; 0.1 vs 1 μg/mL). Under LPS (1 μg/mL) stimulation in both cell types, naringenin (up to 200 μmol/L in macrophages and 100 μmol/L in microglia) inhibited nitrite production and inducible nitric oxide synthase and cyclooxygenase-2 expression in a dose-dependent manner. The range of naringenin concentrations for inhibition was broader, and the lowest concentration was more easily achieved in macrophages; the lowest effective concentrations of naringenin to achieve constant suppression effect were 50 μmol/L in macrophages and 100 μmol/L in microglia, respectively. Vitamin C (100 μmol/L), compared with naringenin (100 μmol/L), had less and no suppression effect on LPS (1 μg/mL)-induced nitrite production in macrophages and microglia, respectively. In conclusion, naringenin more effectively inhibits the LPS-induced inflammatory status, including nitrite production and inducible nitric oxide synthase and cyclooxygenase-2 expression, in macrophages than in microglia. The findings of the present study suggest that consumption of naringenin-containing flavonoids might be beneficial to the cardiovascular and cerebrovascular inflammatory process.

Comparative effects of low-intensity pulsed ultrasound and low-level laser therapy on injured skeletal muscle

OBJECTIVE

The main purpose of this study was to compare the effects of low-intensity pulsed ultrasound (US) and low-level laser therapy (LLLT) on injured skeletal muscle after cryolesion by means of histopathological analysis and immunohistochemistry for cyclo-oxygenase-2 (COX-2).

BACKGROUND AND METHODS

Thirty-five male Wistar rats were randomly distributed into four groups: intact control group with uninjured and untreated animals; injured control group with muscle injury and no treatment; LLLT-treated group with muscle injury treated with 830-nm laser; and US-treated group with muscle injury treated with US. Treatments started 24 h postsurgery and were performed during six sessions.

RESULTS

LLLT-treated animals presented minor degenerative changes of muscle tissue. Exposure to US reduced tissue injuries induced by cryolesion, but less effectively than LLLT. A large number of COX-2 positive cells were found in untreated injured rats, whereas COX-2 immunoexpression was lower in both LLLT- and US-treated groups.

CONCLUSION

This study revealed that both LLLT and US therapies have positive effects on muscle metabolism after an injury in rats, but LLLT seems to produce a better response.

Cardioprotective effect of melatonin against isoproterenol induced myocardial infarction in rats: A biochemical, electrocardiographic and histoarchitectural evaluation

The present study was designed to investigate the cardioprotective effect of melatonin against isoproterenol induced myocardial infarction in rats by studying myocyte injury markers, antioxidant defense system, serum and heart lipid profile, inflammatory markers, electrocardiographic and histopathological changes. Male Sprague Dawley (SD) rats were randomly divided into four groups, namely control, melatonin, isoproterenol and melatonin+isoproterenol treated group. Melatonin treatment group received melatonin (10mg/kg/day, i.p.) for 7days. Myocardial infarction in rats was induced by isoproterenol administration (150mg/kg, s.c.) at an interval of 24h on 6th and 7th day. On 8th day ECG, gravimetric, biochemical and histopathological parameters were assessed. Isoproterenol administration showed changes in ECG pattern, including ST-segment elevation (diagnostic of myocardial infarction) increase in the serum levels of cardiac injury markers (creatine kinase-MB, lactate dehydrogenase, aspartate transaminase and alanine transaminase), decreased antioxidant defense system in the heart and altered lipid profile in the serum and heart. Isoproterenol administration also resulted in release of inflammatory markers and neutrophil infiltration along with histopathological changes. Melatonin pre-co-treatment prevented almost all the parameters of isoproterenol induced myocardial infarction in rats. The above finding was confirmed by the histopathological examination. In the baseline group (melatonin alone treated group) no significant change was observed. Results of the present study suggest that melatonin has a significant effect on the protection of the heart against isoproterenol induced myocardial infarction through maintaining endogenous antioxidant enzyme activities.

Vitamin C prevents DNA damage induced by renovascular hypertension in multiple organs of Wistar rats

The aim of this study was to investigate, through the single-cell gel (comet) assay, whether vitamin C is able to protect against renovascular hypertension-induced genotoxicity in multiple organs. A total of 32 male Wistar rats were divided into four groups: negative control (n = 6); animals treated with vitamin C (n = 6); hypertensive rats (n = 10) and hypertensive rats and treated with vitamin C (n = 10). Hypertension was induced as a result of partial obstruction of the left renal artery by means of a silver clip during 6 weeks. Vitamin C was administered at 150 mg/kg during 7 consecutive days before the end of the experimental period. The results showed that vitamin C was able to protect blood cells against hypertension-induced genotoxicity. Brain, liver and heart cells were also protected by vitamin C following hypertension-induced genotoxic damage. Regarding blood pressure, vitamin C reduced the hypertensive state. In conclusion, our results suggest that vitamin C can prevent hypertension-induced DNA damage in blood, liver, brain and heart cells as well as to normalize the blood pressure of rats.