Apoptotic cell death during ischemia/reperfusion and its attenuation by antioxidant therapy

Bibliometric analysis of research progress on tetramethylpyrazine and its effects on ischemia-reperfusion injury

In recent decades, natural products have attracted worldwide attention and become one of the most important resources for pharmacological industries and medical sciences to identify novel drug candidates for disease treatment. Tetramethylpyrazine (TMP) is an alkaloid extracted from Ligusticum chuanxiong Hort., which has shown great therapeutic potential in cardiovascular and cerebrovascular diseases, liver and renal injury, as well as cancer. In this review, we analyzed 1270 papers published on the Web of Science Core Collection from 2002 to 2022 and found that TMP exerted significant protective effects on ischemia-reperfusion (I/R) injury that is the cause of pathological damages in a variety of conditions, such as ischemic stroke, myocardial infarction, acute kidney injury, and liver transplantation. TMP is limited in clinical applications to some extent due to its rapid metabolism, a short biological half-life and poor bioavailability. Obviously, the structural modification, administration methods and dosage forms of TMP need to be further investigated in order to improve its bioavailability. This review summarizes the clinical applications of TMP, elucidates its potential mechanisms in protecting I/R injury, provides strategies to improve bioavailability, which presents a comprehensive understanding of the important compound. Hopefully, the information and knowledge from this review can help researchers and physicians to better improve the applications of TMP in the clinic.

Inhibition of circ_0073932 attenuates myocardial ischemia‒reperfusion injury via miR-493-3p/FAF1/JNK

Oxidative stress and apoptosis play crucial roles in myocardial ischemia‒reperfusion injury (MIRI). In this study, we investigated the role of circ_0073932 in MIRI as well as its molecular mechanism. A hypoxia/reoxygenation (H/R) cardiomyocyte model was established with H9C2 cardiomyocytes, and RT-qPCR was used to measure gene expression. We observed that circ_0073932 expression was abnormally increased in the H/R cardiomyocyte model and in blood samples from MIRI patients. Inhibition of circ_0073932 suppressed H/R-induced cell apoptosis, oxidative stress (ROS, LDH and MDA), and p-JNK expression. Dual luciferase reporter assays showed that circ_0073932 targeted the downregulation of miR-493-3p, and miR-493-3p targeted the downregulation of FAF1. Furthermore, si-circ_0073932, an miR-493-3p inhibitor, oe-FAF1, or si-FAF1 were transfected into H9C2 cardiomyocytes to investigate the roles of these factors in MIRI. Our results showed that compared with the H/R group, si-circ_0073932 inhibited H/R-induced cell apoptosis, oxidative stress (ROS, LDH and MDA), and p-JNK expression. These results were reversed by the miR-493-3p inhibitor or oe-FAF1. Finally, a rat model of MIRI was established, and si-circ_0073932 was administered. Inhibition of circ_0073932 reduced the area of myocardial infarction and decreased the levels of apoptosis and oxidative stress by inhibiting the JNK signaling pathway. Our study indicated that circ_0073932 mediates MIRI via miR-493-3p/FAF1/JNK in vivo and in vitro, revealing novel insights into the pathogenesis of MIRI and providing a new target for the clinical treatment of MIRI.

The Flt3-inhibitor quizartinib augments apoptosis and promotes maladaptive remodeling after myocardial infarction in mice

BACKGROUND

Tyrosine kinase inhibitors (TKIs) targeting fms-like tyrosine kinase 3 (Flt3) such as quizartinib were specifically designed for acute myeloid leukemia treatment, but also multi-targeting TKIs applied to solid tumor patients inhibit Flt3. Flt3 is expressed in the heart and its activation is cytoprotective in myocardial infarction (MI) in mice.

OBJECTIVES

We sought to test whether Flt3-targeting TKI treatment aggravates cardiac injury after MI.

METHODS AND RESULTS

Compared to vehicle, quizartinib (10 mg/kg/day, gavage) did not alter cardiac dimensions or function in healthy mice after four weeks of therapy. Pretreated mice were randomly assigned to MI or sham surgery while receiving quizartinib or vehicle for one more week. Quizartinib did not aggravate the decline in ejection fraction, but significantly enhanced ventricular dilatation one week after infarction. In addition, apoptotic cell death was significantly increased in the myocardium of quizartinib-treated compared to vehicle-treated mice. In vitro, quizartinib dose-dependently decreased cell viability in neonatal rat ventricular myocytes and in H9c2 cells, and increased apoptosis as assessed in the latter. Together with H2O2, quizartinib potentiated the phosphorylation of the pro-apoptotic mitogen activated protein kinase p38 and augmented H2O2-induced cell death and apoptosis beyond additive degree. Pretreatment with a p38 inhibitor abolished apoptosis under quizartinib and H2O2.

CONCLUSION

Quizartinib potentiates apoptosis and promotes maladaptive remodeling after MI in mice at least in part via a p38-dependent mechanism. These findings are consistent with the multi-hit hypothesis of cardiotoxicity and make cardiac monitoring in patients with ischemic heart disease under Flt3- or multi-targeting TKIs advisable.

Mitochondria-derived methylmalonic acid aggravates ischemia-reperfusion injury by activating reactive oxygen species-dependent ferroptosis

Ferroptosis is a regulatory cell death process pivotal in myocardial ischemia-reperfusion (I/R) injury. However, the precise mechanism underlying myocardial ferroptosis remains less known. In this study, we investigated the pathophysiological mechanisms of methylmalonic acid (MMA) associated with ferroptosis activation in cardiomyocytes after I/R. We found an increase level of MMA in patients with acute myocardial injury after reperfusion and AC16 cells under hypoxia/reoxygenation (H/R) condition. MMA treatment was found to be associated with excessive oxidative stress in cardiomyocytes, leading to ferroptosis-related myocardial injury. In mice with I/R injury, MMA treatment aggravated myocardial oxidative stress and ferroptosis, which amplified the myocardial infarct size and cardiac dysfunction. Mechanistically, MMA promoted NOX2/4 expression to increase reactive oxygen species (ROS) production in cardiomyocytes, aggravating myocardial injury. Notably, the increased ROS further activated ferroptosis by inhibiting solute carrier family 7 member 11 (SLC7A11) and glutathione peroxidase 4 (GPX4) expression. In addition, MMA decreased the ectopic nuclear distribution of nuclear factor E2-related factor 2 (NRF2) by increasing the interaction between NRF2 and kelch-like ECH-associated protein 1 (KEAP1). This impeded the activation of GPX4/SLC7A11, downstream of NRF2, activating ferroptosis and aggravating myocardial cell injury. Collectively, our study indicates that MMA activates oxidative stress and ROS generation, which induces ferroptosis to exacerbate cardiomyocyte injury in an I/R model. These findings may provide a new perspective for the clinical treatment of I/R injury and warrant further investigation.

Activation of the Nrf-2/HO-1 signalling axis can alleviate metabolic syndrome in cardiovascular disease

Background: Cardiovascular disease (CVD) is widely observed in modern society. CVDs are responsible for the majority of fatalities, with heart attacks and strokes accounting for approximately 80% of these cases. Furthermore, a significant proportion of these deaths, precisely one-third, occurs in individuals under 70. Metabolic syndrome encompasses a range of diseases characterized by various physiological dysfunctions. These include increased inflammation in adipose tissue, enhanced cholesterol synthesis in the liver, impaired insulin secretion, insulin resistance, compromised vascular tone and integrity, endothelial dysfunction, and atheroma formation. These factors contribute to the development of metabolic disorders and significantly increase the likelihood of experiencing cardiovascular complications.Method: We selected studies that proposed hypotheses regarding metabolic disease syndrome and cardiovascular disease (CVD) and the role of Nrf2/HO-1 and factor regulation in CVD research investigations based on our searches of Medline and PubMed.Results: A total of 118 articles were included in the review, 16 of which exclusively addressed hypotheses about the role of Nrf2 on Glucose regulation, while 16 involved Cholesterol regulation. Likewise, 14 references were used to prove the importance of mitochondria on Nrf2. Multiple studies have provided evidence suggesting the involvement of Nrf2/HO-1 in various physiological processes, including metabolism and immune response. A total of 48 research articles and reviews have been used to highlight the role of metabolic syndrome and CVD.Conclusion: This review provides an overview of the literature on Nrf2/HO-1 and its role in metabolic disease syndrome and CVD.

Mechanism in bradycardia induced by Trimethyltin chloride: Inhibition activity and expression of Na+/K+-ATPase and apoptosis in myocardia

Trimethyltin chloride (TMT) is a stabilizer by-product in the process of manufacturing plastic, which is a kind of very strong toxic substance, and has acute, cumulative and chronic toxicity. TMT may cause bradycardia in patients with occupational poisoning, the mechanism of which has not been reported. This study explored the mechanism of TMT resulting in bradycardia of C57BL/6 mice. TMT was administered to mice to measure heart rate, serum succinate dehydrogenase (SDH) level, and myocardial Na⁺/K⁺-ATPase activity and expression. The effects of TMT on myocardial apoptosis were observed by changing the expressions of caspase-3, Bax and Bcl-2 in myocardium. It was found that the heart rate and SDH activity in serum of mice gradually decreased with the increase of TMT dose compared with the control group. The activity and the expression of Na⁺/K⁺-ATPase in the heart tissue of mice exposed to TMT was measured and gradually decreased with the increase of dose and time. We measured the expression of Bcl-2, Bax, caspase-3 and cleaved caspase-3 in the heart tissues of TMT exposed mice and found that the expressions of Bax, caspase-3 and cleaved caspase-3 increased and the expressions of Bcl-2 decreased in the heart tissues of the TMT-exposed mice at different doses. With the extension of TMT exposure time, the expression of Bax and caspase-3 increased and the expression of Bcl-2 decreased in the heart tissues of TMT exposed mice. Our findings suggest the mechanisms of TMT resulting in bradycardia may be associated with the inhibited activity and decreased content of Na⁺/K⁺-ATPase, thus further leading to the changes of Bcl-2, Bax, caspase-3 and cleaved caspase-3 in the mice's ventricular tissues.

Vitamin C: historical perspectives and heart failure

Vitamin C (Vit C) is an ideal antioxidant as it is easily available, water soluble, very potent, least toxic, regenerates other antioxidants particularly Vit E, and acts as a cofactor for different enzymes. It has received much attention due to its ability in limiting reactive oxygen species, oxidative stress, and nitrosative stress, as well as it helps to maintain some of the normal metabolic functions of the cell. However, over 140 clinical trials using Vit C in different pathological conditions such as myocardial infarction, gastritis, diabetes, hypertension, stroke, and cancer have yielded inconsistent results. Such a divergence calls for new strategies to establish practical significance of Vit C in heart failure or even in its prevention. For a better understanding of Vit C functioning, it is important to revisit its transport across the cell membrane and subcellular interactions. In this review, we have highlighted some historical details of Vit C and its transporters in the heart with a particular focus on heart failure in cancer chemotherapy.

Vitamin C for Cardiac Protection during Percutaneous Coronary Intervention: A Systematic Review of Randomized Controlled Trials

Percutaneous coronary intervention (PCI) is the preferred treatment for acute coronary syndrome (ACS) secondary to atherosclerotic coronary artery disease. This nonsurgical procedure is also used for selective patients with stable angina. Although the procedure is essential for restoring blood flow, reperfusion can increase oxidative stress as a side effect. We address whether intravenous infusion of vitamin C (VC) prior to PCI provides a benefit for cardioprotection. A total of eight randomized controlled trials (RCT) reported in the literature were selected from 371 publications through systematic literature searches in six electronic databases. The data of VC effect on cardiac injury biomarkers and cardiac function were extracted from these trials adding up to a total of 1185 patients. VC administration reduced cardiac injury as measured by troponin and CK-MB elevations, along with increased antioxidant reservoir, reduced reactive oxygen species (ROS) and decreased inflammatory markers. Improvement of the left ventricular ejection fraction (LVEF) and telediastolic left ventricular volume (TLVV) showed a trend but inconclusive association with VC. Intravenous infusion of VC before PCI may serve as an effective method for cardioprotection against reperfusion injury.

Protective effects of fisetin against myocardial ischemia/reperfusion injury

The underlying mechanism of the myocardial protective effect of fisetin was studied in a rat ischemia/reperfusion injury model. Sprague-Dawley rats were randomly assigned to seven groups and pretreated with different solutions by gavage administration. A rat model of cardiac ischemia/reperfusion injury was established. Plasma levels of Von Willebrand factor (vWF) were determined by ELISA, flow cytometry was used to determine the level of cardiomyocyte apoptosis and 2,3,5-triphenyltetrazolium staining was used to determine the size of myocardial infarcts. Hematoxylin and eosin-stained sections of myocardial tissues were examined for pathological changes. Expressions of nuclear factor (NF)-κB and matrix metallopeptidase 9 (MMP-9) were measured by immunohistochemistry. Compared with the model group, rats pretreated with fisetin, quercetin and aspirin showed significant prolongation of clotting time, prothrombin time, thrombin time and activated partial thromboplastin time. Fisetin treatment better maintained the integrity of myocardial fibers and nuclear integrity, reduced the percentage of apoptotic myocardial cells, inhibited expression of NF-κB, decreased the loss of MMP-9 and reduced nuclear translocation of NF-kB. Rats pretreated with fisetin also demonstrated a significant decrease in plasma levels of vWF. In addition, the protective effect of fisetin on myocardial cells was found to be dose dependent.

Reperfusion injury as a target for diminishing infarct size

Therapies for preventing reperfusion injury (RI) have been widely studied. However, the attempts to transfer cardioprotective therapies for reducing RI from experiments into clinical practice have been so far unsuccessful. Pathophysiological mechanisms of RI are complicated and compose of many pathways e.g. hypercontracture-mediated sarcolemma rupture, mitochondrial permeability transition pore persistent opening, reactive oxygen species formation, inflammation and no-reflow phenomenon. Based on research, it cannot be determined which mechanism dominates, probably they cooperate with a domination of one or another in different clinical circumstances. Our hypothesis is, that only intervention that at the same time interferes with different (all?) pathways of RI may turn out to be effective in decreasing the final area of infarction.

The possible alleviating effect of saffron on chlorpyrifos experimentally induced cardiotoxicity: Histological, immunohistochemical and biochemical study

INTRODUCTION

Pesticides are responsible for many occupational health hazards among farmers in developing countries. Chlorpyrifos (CPF) is one of the broad-spectrum organophosphorus (OP) insecticides used for agricultural, domestic and industrial purposes.

AIM OF THE WORK

The present study was designed to examine the effects of CPF on cardiac muscles and to evaluate the possible protective role of crocin using biochemical and histological methods with the intention to recognize the molecular tools of its probable cardioprotective effects.

MATERIALS AND METHODS

Thirty-six adult male albino rats were used in this study and were divided into 4 equal groups (9 rats each): negative control group, positive control group, CPF treated group and CPF & crocin treated group. The heart was removed for histological and immunohistochemical studies.

RESULTS

Stained sections of cardiac muscle fibers of group III with H&E revealed remarkable histological changes in the form of disorganization of the fibers with increase in the interstitial spaces between these fibers. Congested dilated blood capillaries could be observed with extravasation of the red blood cells leading to interstitial hemorrhage. Focal areas of mononuclear cellular infiltration could be seen in the interstitial tissue. A number of cardiac fibers achieved pale acidophilic vacuolated sarcoplasm while others achieved dark homogenous acidophilic sarcoplasm. Some nuclei were peripherally situated and pyknotic while others were centrally situated and encircled with halos. Apparently increased masses of collagen fibers among the cardiac muscle fibers and around the congested dilated blood vessels with the presence of focal parts of extensive collagen fiber deposition were noticed in Mallory-stained sections of group III. Strong positive immunoreactions in the endomysium and perimysium of the cardiac fibers, along with the walls of blood capillaries and in interstitial cells, could be detected in immunohistochemical staining sections of group III with vimentin antibody. Immunoreactivity to caspase 3 was higher in the sarcoplasm of the cardiac fibers of group III compared to that of control group. A highly significant decrease in the cardiac level of SOD and CAT; however, a highly significant increase in MDA level was noted between the control groups and CPF treated group. Additionally, there was a significant improvement of the chemical and histological representations of group IV, and these improvement pictures were toward the normal.

CONCLUSION

The study concludes that crocin can alleviate the toxic effect of chlorpyrifos caused by oxidative stress on cardiac muscle.

Berbamine ameliorates isoproterenol-induced myocardial infarction by inhibiting mitochondrial dysfunction and apoptosis in rats

Berbamine (BBM), a bisbenzylisoquinoline alkaloid from roots, bark, and stem of Berberis plant such as Berberis aristata has a wide range of pharmacological activities. However, the evidence for the cardioprotective effect of BBM is inadequate and the molecular mechanism of BBM remains unclear. This study investigated the underlying molecular mechanism of BBM-mediated cardioprotection on isoproterenol (ISO)-induced mitochondrial dysfunction and apoptosis in rats. The assays of mitochondria antioxidant status, mitochondrial marker enzymes, and electron microscopic analysis of mitochondria revealed BBM significantly prevented the mitochondrial dysfunction induced by ISO. The ISO-induced elevation of mitochondrial oxidative stress was also curbed by BBM. Furthermore, pretreatment with BBM protected the heart tissue from ISO-induced apoptosis as evident from decreased terminal dUTP nickend-labeling positive cells and decreased expression of Bax, cytochrome c, cleaved caspase-9, and caspase-3, and poly (ADP-ribose) polymerase and increased expression of Bcl-2 in ISO-induced rats. These current findings suggest that BBM exerts a significant cardioprotective effect on ISO-induced myocardial infarction in rats.

Conotoxin MVIIA improves cell viability and antioxidant system after spinal cord injury in rats

This study evaluates whether intrathecal MVIIA injection after spinal cord injury (SCI) elicits neuroprotective effects. The test rats were randomly distributed into six groups— sham, placebo, MVIIA 2.5 μM, MVIIA 5 μM, MVIIA 10 μM, and MVIIA 20 μM—and were administered the treatment four hours after SCI. After the optimal MVIIA dose (MVIIA 10 μM) was defined, the best time for application, one or four hours, was analyzed. Locomotor hind limb function and side effects were assessed. Forty-eight hours after the injury and immediately after euthanasia, spinal cord segments were removed from the test rats. Cell viability, reactive oxygen species, lipid peroxidation, and glutamate release were investigated. To examine the MVIIA mechanism of action, the gene expressions of pro-apoptotic (Bax, nNOS, and caspase-3, -8, -9, -12) and anti-apoptotic (Bcl-xl) factors in the spinal cord tissue samples were determined by real-time PCR, and the activities of antioxidant enzymes were also investigated. Application of intrathecal MVIIA 10 μM four hours after SCI prompted a neuroprotective effect: neuronal death decreased (22.46%), oxidative stress diminished, pro-apoptotic factors (Bax, nNOS, and caspase-3, -8) were expressed to a lesser extent, and mitochondrial viability as well as anti-apoptotic factor (Bcl-xl) expression increased. These results suggested that MVIIA provided neuroprotection through antioxidant effects. Indeed, superoxide dismutase (188.41%), and glutathione peroxidase (199.96%), reductase (193.86%), and transferase (175.93%) expressions increased. Therefore, intrathecal MVIIA (MVIIA 10 μM, 4 h) application has neuroprotective potential, and the possible mechanisms are related to antioxidant agent modulation and to intrinsic and extrinsic apoptotic pathways.

Teucrium polium L. Improved Heart Function and Inhibited Myocardial Apoptosis in Isolated Rat Heart Following Ischemia-Reperfusion Injury

OBJECTIVES

Myocardial reperfusion is the only logical cure for ischemic heart disease. However, ischemic-reperfusion (I/R) injury is one of the underlying factors facilitating and accelerating the apoptosis in the myocardium. This study set to investigate the impact of Teucrium polium (TP) hydro-alcoholic extract on I/R induced apoptosis in the isolated rat heart.

METHODS

Isolated rat hearts were classified into six groups. The control samples were subjected to 80 min of perfusion with Krebs-Henseleit bicarbonate (KHB) buffer; in control-ischemia group, after primary perfusion (20 min) the hearts were exposed to global ischemia (20 min) and reperfusion (40 min). Pretreated groups were perfused with 500 μM of vitamin C and various TP concentrations (0.5, 1, 2 mg/ml) for 20 min, and then the hearts were exposed to ischemia and reperfusion for 20 min and 40 min, respectively. Cardiodynamic parameters including rate pressure product (RPP), heart rate (HR), the maximum up/down rate of left ventricular pressure (±dp/dt), left ventricular developed pressure (LVDP), and coronary artery flow (CF) were achieved from Lab Chart software data. The Bax and BCl-2 gene expressions were measured in heart samples.

RESULTS

Hearts treated with TP extract and vit C represented a meaningful improvement in cardiac contractile function and CF. The overexpression of Bcl-2, downregulation of Bax, and improvement of apoptotic index (Bax/Bcl-2) were observed in pretreated TP extract and vit C hearts.

CONCLUSION

The TP extract was found to ameliorate the cardiac function in the reperfused myocardium. Also, it can hinder apoptotic pathways causing cardioprotection.

Protective effect of propofol on ischemia-reperfusion injury detected by HPLC-MS/MS targeted metabolic profiling

Ischemia-reperfusion injury(IRI), described as tissue damage caused by reversible ischemic injury or hypoxia prior to the blood supply restoration, is a common pathological phenomenon. In recent study, a hypoxia-reoxygenation (H/R) in the presence or absence of propofol posthypoxia treatment (P-PostH) cell model was built to simulate the condition of IRI, and researchers found propofol may protect cells by suppressing autophagic cell death. To investigate the mechanism underling the protective effect of propofol. A metabolomic analysis was performed in this study using ultra performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF- MS) to compare the metabolism during the process of H/R in the presence or absence of P-PostH. A total of 22 metabolites were detected varied after propofol posthypoxia treatment. Pathway analysis revealed these metabolites were mainly involved in the purine metabolic pathway, three carboxylic acid metabolic pathways, alanine, aspartate and glutamate metabolism pathway and lipid metabolism pathway. We measured the level of Hypoxanthine to verify the metabolomics work, for pathway analysis, we detect the level of reactive oxygen species with H/R and P-PostH treatment. Our study achieved a global comparison of metabolism profiling of H/R cell model with or without propofol posthypoxic treatment. The result indicated that propofol can attenuate endothelial injury caused by IRI by reducing oxidative damage.

N-acetylcysteine protects against diabetic nephropathy through control of oxidative and nitrosative stress by recovery of nitric oxide in rats

The diabetes mellitus (DM) induces several changes, with substantial increase of reactive oxygen species (ROS). The ROS cause damage to systemic and renal microvasculature, which could be one of the mechanisms involved in the development of diabetic nephropathy (DN). The ROS modulate other substances like the nitric oxide (NO), a vasodilator with important role in the renal function. N-acetylcysteine (NAC) is an antioxidant that acts replenishing intracellular cysteine levels, which is essential for glutathione formation. The aim of this study was to evaluate the effect of early or late NAC treatment on oxidative/nitrosative stress in DN progression. All rats were submitted to unilateral nephrectomy and diabetes was induced with streptozotocin. The animals were allocated into six groups: controls that received water (CTL) or NAC (CTL + NAC); diabetic groups that received early or late, water (DM-E; DM-L) or NAC (DM + NAC-E; DM + NAC-L), started on 5th day (early) or 4th week (late) after diabetes induction, during 8 weeks. After NAC treatment, the rats were placed in individual metabolic cages to obtain urine and blood samples for analysis of metabolic profile, renal function, thiobarbituric acid reactive substances (TBARS) and NO. At the end of the protocol, the renal cortex was removed for TBARS, NOS evaluation, antioxidants markers and histology. The DM-E group compared to CTL showed a significant increase in glycemia and proteinuria and impaired renal function; there was a significant increase of TBARS in plasma, urine and renal tissue, and also a significant decrease in plasma NO, which were reverted after early NAC treatment. The eNOS was decreased and iNOS was increased in DM-E vs. CTL, p < 0.05. The early NAC treatment in DM rats reduced proteinuria, creatinine, urea, TBARS and iNOS and, increased creatinine clearance, NO and eNOS, increasing significantly the antioxidant defenses, promoting elevated catalase and glutathione compared to DM-E group, all p < 0.05. The late NAC treatment in diabetic rats vs.DM-E showed reduced proteinuria and TBARS excretion and higher values of creatinine clearance and NO, all statistically significant. Histological analysis of the animals in DM-E or DM-L showed significant tubular changes with degeneration and vacuolization in tubular cells, dilated tubular lumen, intense glycosidic degeneration, and discreet mesangial expansion with interstitial fibrosis area. The DM + NAC-E group showed moderate glycosidic degeneration, however, did not present tubular degeneration or fibrosis. The DM + NAC-L group showed severe glycosidic degeneration, moderate tubular cell degeneration, light and focal dilatation of the tubules, with no fibrosis. Our study showed that NAC protected the diabetic rats against renal injury, probably due to the control of oxidative stress via recovery of the NO bioavailability, showing that early NAC was more effective than late treatment. All these data suggest that NAC may be useful in the adjuvant treatment in a safe way, in the early phase of the disease. Eventually, prolonged treatment, even if it is started later, could change the natural history of the disease, delaying the complications of diabetes in renal tissue.

MicroRNA‑20b‑5p promotes ventricular remodeling by targeting the TGF‑β/Smad signaling pathway in a rat model of ischemia‑reperfusion injury

Myocardial ischemic injury results from severe impairment of the coronary blood supply and may lead to metabolic and ultrastructural changes, thereby causing irreversible damage. MicroRNA (miR)-20b-5p has been demonstrated to be involved in malignancies of the breast, colorectum, stomach, blood and oropharynx. The present study aimed to investigate the effects of miR-20b-5p on ventricular remodeling following myocardial ischemia-reperfusion (IR) injury in rats by targeting small mothers against decapentaplegic homolog 7 (Smad7) via the transforming growth factor-β (TGF-β)/Smad signaling pathway. A total of 70 adult male Sprague-Dawley rats were divided into seven groups: Sham group, IR group, negative control group, miR-20b-5p mimics group, miR-20b-5p inhibitors group, small interfering RNA (siRNA)-Smad7 group, and miR-20b-5p inhibitors + siRNA-Smad7 group. Dual luciferase reporter gene assays were used to verify the association between miR-20b-5p and Smad7. Myocardial infarction size, myocardial collagen volume fraction and perivascular collagen area were detected separately using triphenyltetrazolium chloride and Masson's staining. The rate of positive expression of Smad7 was detected using immunohistochemistry, and the expression levels of miR-20b-5p, TGF-β1, Smad3 and Smad7 were detected using reverse transcription-quantitative polymerase chain reaction and western blot analyses. The findings revealed that miR-20b-5p inhibited Smad7. Compared with the sham group, the other six groups had increased myocardial infarction size, myocardial collagen, and expression of miR-20b-5p, TGF-β1 and Smad3, and decreased expression of Smad7. Compared with the IR group, the miR-20b-5p mimics group and the siRNA-Smad7 group had increased myocardial infarction size and myocardial collagen, increased expression of TGF-β1 and Smad3, and decreased expression of Smad7. The expression of miR-20b-5p was markedly increased in the miR-20b-5p mimics group, but did not differ significantly from that in the siRNA-Smad7 group. The results demonstrated that miR-20b-5p promoted ventricular remodeling following myocardial IR injury in rats by inhibiting the expression of Smad7 through activating the TGF-β/Smad signaling pathway.

Antioxidant Therapeutic Strategies for Cardiovascular Conditions Associated with Oxidative Stress

Oxidative stress (OS) refers to the imbalance between the generation of reactive oxygen species (ROS) and the ability to scavenge these ROS by endogenous antioxidant systems, where ROS overwhelms the antioxidant capacity. Excessive presence of ROS results in irreversible damage to cell membranes, DNA, and other cellular structures by oxidizing lipids, proteins, and nucleic acids. Oxidative stress plays a crucial role in the pathogenesis of cardiovascular diseases related to hypoxia, cardiotoxicity and ischemia-reperfusion. Here, we describe the participation of OS in the pathophysiology of cardiovascular conditions such as myocardial infarction, anthracycline cardiotoxicity and congenital heart disease. This review focuses on the different clinical events where redox factors and OS are related to cardiovascular pathophysiology, giving to support for novel pharmacological therapies such as omega 3 fatty acids, non-selective betablockers and microRNAs.

Role of carvacrol in cardioprotection against myocardial ischemia/reperfusion injury in rats through activation of MAPK/ERK and Akt/eNOS signaling pathways

Carvacrol (CAR) is a compound isolated from some essential oils, many studies have demonstrated its therapeutic potential on different diseases. This study aims to evaluate the protective effect of CAR against myocardial ischemia/reperfusion (I/R) injury in rats. Male adult rats underwent ligation of the left anterior descending coronary artery (LAD) in I/R models. Rats were treated with CAR after LAD. The levels of I/R- induced infarct size, cardiomyocyte apoptosis and cardiac functional impairment were examined. Levels of superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) were detected by western blotting. Cardiomyocytes induced by hypoxic reperfusion (H/R) injury were tested by Hoechst 33258. Our results revealed that CAR administration significantly protected the heart function, attenuated myocardial infarct size, increased SOD and CAT levels, reduced MDA level and especially decreased cardiomyocytes apoptosis. Western blotting showed that CAR treatment up-regulated phosphorylated ERK (p-ERK), while producing no impact onp38 mitogen-activated protein kinase (p38MAPK) and c-Jun N-terminal kinase (JNK). The cardioprotection of CAR was reversed by the ERK inhibitor PD-98059, demonstrating the involvement of the MAPK/ERK pathway in the anti-apoptotic mechanisms of CAR. Besides, the results in vitro also showed the protective efficiency of CAR on cardiomyocytes H/R injury. Furthermore, pretreatment with CAR markedly increased the activation of Akt/eNOS pathway in cardiomyocytes subjected to H/R, and the protective effects of CAR were abolished in the presence of the Akt inhibitor LY294002. Therefore, the cardioprotective effects of CAR may be attributed to its antioxidant and antiapoptotic activities through activations of the MAPK/ERK and Akt/eNOS signaling pathways.

Cardioprotection by Carvedilol: Antiapoptosis is Independent of β-Adrenoceptor Blockage in the Rat Heart

Background: Carvedilol, a β-blocking agent with α-blocking properties is now widely used for the treatment of congestive heart failure. In addition to its β-adrenergic receptor blockage, antiapoptotic effects have been demonstrated in experimental animals.

Objective: The cardioprotective effects of carvedilol and its hydroxylated analogue BM-91.0228 were tested with regard to their infarct-limiting and antiapoptotic properties in an experimental infarct model in the rat heart.

Methods: Anesthetized rats were subjected to either 30 (groups I to 3) or 60 minutes (groups. 4 to 6) of coronary artery occlusion followed by 30 minutes of reperfusion. Groups 1 and 4 served as the control; groups 2 and 5 received intravenous Carvedilol (1 mg/kg) and groups 3 and 6 received intravenous administration of BM-91.0228 (1 mg/kg), respectively, 5 minutes prior to coronary occlusion. Infarct sizes were measured by triphenyltetrazolium chloride staining. In situ visualization of apoptosis was measured by nick end labeling.

Results: Carvedilol reduced infarct size after 30 minutes of coronary occlusion compared to controls (8.7% ± 2.7% versus 27.3% ± 3.4%, P < .001), while BM-91.0228 showed no significant infarct size reduction (23.7% ± 5.9%, NS). Neither Carvedilol (36.9% ± 3.9%) nor BM-91.0228 (42.4% ± 3.6%) reduced infarct size after 60 minutes of coronary occlusion compared to controls (47.7% ± 3.9%, NS). Carvedilol reduced apoptosis after 30 minutes (4.9% ± 1.3% versus 16.7% ± 3.2%, P < .01) and after 60 minutes (11.7% ± 1.8% versus 25.5% ± 0.5%, P < .001) of coronary occlusion compared to controls. BM-91.0228 reduced apoptosis after 30 minutes (7.3% ± 1.4% versus 16.7% ± 3.2%, P < .01) and after 60 minutes (13.4% ± 1.8% versus 25.5% ± 0.5%, P < .001) of coronary occlusion compared to controls.

Conclusion: Carvedilol is cardioprotective by preventing ischemia-perfusion-induced necrosis and apoptosis of cardiomyocytes. The antiapoptotic effects of Carvedilol are independent of its β-adrenoceptor blocking effects, but its effects might be caused by antioxidant properties and by modulation of the signalling pathway.

Protective effects of p-nitro caffeic acid phenethyl ester on acute myocardial ischemia-reperfusion injury in rats

Myocardial ischemia-reperfusion (IR) causes widespread cardiomyocyte dysfunction, including apoptosis and necrosis. The present study aimed to investigate the possible cardioprotective effects of p-nitro caffeic acid phenethyl ester (CAPE-NO₂) on myocardial IR-induced injury in vivo. To generate a rat model of myocardial IR, the left anterior descending coronary artery was occluded for 30 min, followed by reperfusion for 2 h. The rats were administered either the sham treatment (the sham and IR control groups) or the therapeutic agents [the caffeic acid phenethyl ester (CAPE) and CAPE-NO₂ groups] 10 min prior to the occlusion. Myocardial IR-induced injury is characterized by: A significant increase in the levels of myocardial enzymes, including creatine kinase, lactate dehydrogenase and aspartate transaminase; a marked increase in intercellular adhesion molecule 1 expression levels, lipid peroxidation products and inflammatory mediators; and a significant decrease in myocardial antioxidants, including catalase, total superoxide dismutase and glutathione peroxidase. In the present study, pretreatment with CAPE-NO₂ significantly ameliorated these changes, and decreased the infarct size, as compared with the IR control group (10.32±3.8 vs. 35.65±5.4%). Furthermore, western blotting demonstrated that pretreatment with CAPE-NO₂ downregulated the myocardial IR-induced protein expression levels of B-cell lymphoma-2 (Bcl-2)-associated X protein (Bax), cleaved caspase-3, P38 and the Bax/Bcl-2 ratio. CAPE-NO₂ also upregulated the myocardial IR-induced expression levels of Bcl-2, phosphoinositide-3-kinase, phosphorylated Akt and mammalian target of rapamycin. In conclusion, the results of the present study indicated that CAPE-NO₂ demonstrated improved cardioprotective effects, as compared with CAPE; therefore, CAPE-NO₂ may represent a novel approach to pharmacological cardioprotection.

Cardioprotective and nonprotective regimens of chronic hypoxia diversely affect the myocardial antioxidant systems

It has been documented that adaptation to hypoxia increases myocardial tolerance to ischemia-reperfusion (I/R) injury depending on the regimen of adaptation. Reactive oxygen species (ROS) formed during hypoxia play an important role in the induction of protective cardiac phenotype. On the other hand, the excess of ROS can contribute to tissue damage caused by I/R. Here we investigated the relationship between myocardial tolerance to I/R injury and transcription activity of major antioxidant genes, transcription factors, and oxidative stress in three different regimens of chronic hypoxia. Adult male Wistar rats were exposed to continuous normobaric hypoxia (FiO2 0.1) either continuously (CNH) or intermittently for 8 h/day (INH8) or 23 h/day (INH23) for 3 wk period. A control group was kept in room air. Myocardial infarct size was assessed in anesthetized open-chest animals subjected to 20 min coronary artery occlusion and 3 h reperfusion. Levels of mRNA transcripts and the ratio of reduced and oxidized glutathione (GSH/GSSG) were analyzed by real-time RT-PCR and by liquid chromatography, respectively. Whereas CNH as well as INH8 decreased infarct size, 1 h daily reoxygenation (INH23) abolished the cardioprotective effect and decreased GSH/GSSG ratio. The majority of mRNAs of antioxidant genes related to mitochondrial antioxidant defense (manganese superoxide dismutase, glutathione reductase, thioredoxin/thioredoxin reductase, and peroxiredoxin 2) were upregulated in both cardioprotective regimens (CNH, INH8). In contrast, INH23 increased only PRX5, which was not sufficient to induce the cardioprotective phenotype. Our results suggest that the increased mitochondrial antioxidant defense plays an important role in cardioprotection afforded by chronic hypoxia.

Role of licochalcone C in cardioprotection against ischemia/reperfusion injury of isolated rat heart via antioxidant, anti-inflammatory, and anti-apoptotic activities

AIMS

This study aimed to evaluate the protective effect of licochalcone C against myocardial ischemia/reperfusion injury in rats.

MAIN METHODS

Left ventricular developed pressure (LVDP) and its maximum up/down rate (±dp/dtmax) were recorded as myocardial function. Levels of creatine kinase (CK), lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione/glutathione disulfide (GSH/GSSG) ratio, and tumor necrosis factor-alpha (TNF-α) were determined by using enzyme-linked immunosorbent assay. Cell morphology was observed and mitochondrial damage was assessed by HE coloration and transmission electron microscopy, respectively. Cardiomyocyte apoptosis was determined by using terminal deoxynucleotidyl transferased UTP nick-end labeling (TUNEL).

KEY FINDINGS

Pretreatment with licochalcone C significantly improved the recovery of LVDP and ±dp/dtmax, and increased the levels of SOD and GSH/GSSG ratio. However, pretreatment with licochalcone C not only decreased the TUNEL-positive cell ratio and morphological changes, but also weaken the mitochondrial injury and the levels of CK, LDH, MDA, and TNF-α.

SIGNIFICANCE

These results suggested an important function of licochalcone C extracted from traditional Chinese medicine in the cardioprotection via antioxidant, anti-inflammatory, and anti-apoptotic activities.

N-acetylcysteine reduces oxidative stress, nuclear factor‑κB activity and cardiomyocyte apoptosis in heart failure

The roles of oxidative stress on nuclear factor (NF)‑κB activity and cardiomyocyte apoptosis during heart failure were examined using the antioxidant N‑acetylcysteine (NAC). Heart failure was established in Japanese white rabbits with intravenous injections of doxorubicin, with ten rabbits serving as a control group. Of the rabbits with heart failure, 12 were not treated (HF group) and 13 received NAC (NAC group). Cardiac function was assessed using echocardiography and hemodynamic analysis. Myocardial cell apoptosis, apoptosis‑related protein expression, NF‑κBp65 expression and activity, total anti‑oxidative capacity (tAOC), 8‑iso‑prostaglandin F2α (8‑iso‑PGF2α) expression and glutathione (GSH) expression levels were determined. In the HF group, reduced tAOC, GSH levels and Bcl‑2/Bax ratios as well as increased 8‑iso‑PGF2α levels and apoptosis were observed (all P<0.05), which were effects that were attenuated by the treatment with NAC. NF‑κBp65 and iNOS levels were significantly higher and the P‑IκB‑α levels were significantly lower in the HF group; expression of all three proteins returned to pre‑HF levels following treatment with NAC. Myocardial cell apoptosis was positively correlated with left ventricular end-diastolic pressure (LVEDP), NF‑κBp65 expression and 8‑iso‑PGF2α levels, but negatively correlated with the maximal and minimal rates of increase in left ventricular pressure (+dp/dtmax and ‑dp/dtmin, respectively) and the Bcl‑2/Bax ratio (all P<0.001). The 8‑iso‑PGF2α levels were positively correlated with LVEDP and negatively correlated with +dp/dtmax and ‑dp/dtmin (all P<0.001). The present study demonstrated that NAC increased the antioxidant capacity, decreased the NF‑κB activation and reduced myocardial cell apoptosis in an in vivo heart failure model.

Protective effect of tetramethylpyrazine on myocardial ischemia-reperfusion injury

Myocardial ischemia-reperfusion injury (MIRI) is a common pathological and physiological phenomenon. Tetramethylpyrazine is the extract of the traditional Chinese medicine Chuanxiong, which can exert protective effects on MIRI in multiple ways. This paper reviewed the current research progress and evidence about the cardiovascular effects of tetramethylpyrazine, which included protecting mitochondria and improving energy metabolism, scavenging oxygen free radicals (OFRs) to inhibit lipid peroxidation, attenuating calcium (Ca(2+)) overload and maintaining Ca(2+) homeostasis in cells, inhibiting apoptosis and protecting myocardial cells, interfering with the inflammatory reaction and mitigating cell injury, interfering with cell signaling pathways, and improving function of endothelial cells and protecting myocardial cells. However, further rigorously designed randomized controlled trials are warranted.

Mitochondrial translocation of Nur77 induced by ROS contributed to cardiomyocyte apoptosis in metabolic syndrome

Metabolic syndrome is a major risk factor for cardiovascular diseases, and increased cardiomyocyte apoptosis which contributes to cardiac dysfunction after myocardial ischemia/reperfusion (MI/R) injury. Nur77, a nuclear orphan receptor, is involved in such various cellular events as apoptosis, proliferation, and glucose and lipid metabolism in several cell types. Apoptosis is positively correlated with mitochondrial translocation of Nur77 in the cancer cells. However, the roles of Nur77 on cardiac myocytes in patients with metabolic syndrome remain unclear. The objective of this study was to determine whether Nur77 may contribute to cardiac apoptosis in patients with metabolic syndrome after I/R injury, and, if so, to identify the underlying molecular mechanisms responsible. We used leptin-deficient (ob/ob) mice to make metabolic syndrome models. In this report, we observed that, accompanied by the substantial decline in apoptosis inducer Nur77, MI/R induced cardiac dysfunction was manifested as cardiomyopathy and increased ROS. Using the neonatal rat cardiac myocytes cultured in a high-glucose and high-fat medium, we found that excessive H2O2 led to the significant alteration in mitochondrial membrane potential and translocation of Nur77 from the nucleus to the mitochondria. However, inhibition of the relocation of Nur77 to mitochondria via Cyclosporin A reversed the changes in membrane potential mediated by H2O2 and reduced myocardial cell injury. Therefore, these data provide a potential underlying mechanism for cardiac dysfunction in metabolic syndrome and the suppression of Nur77 translocation may provide an effective approach to reduce cardiac injury in the process.

Altered expression of calcineurin, calpain, calpastatin and HMWCaMBP in cardiac cells following ischemia and reperfusion

A rise in intracellular myocardial Ca(2+) during cardiac ischemia activates calpain (Calpn) thereby causing damage to myocardial proteins, which leads to myocyte death and consequently to loss of myocardial structure and function. Calcineurin (CaN) interacts with Calpn and causes cellular damage eventually leading to cell death. Calpastatin (Calp) and high molecular weight calmodulin-binding protein (HMWCaMBP) (homolog of Calp), inhibit Calpn activity and thus prevent cell death. CaN stimulation can also result in self-repair of damaged cardiomyocytes. The present study attempts to elucidate the expression of these proteins in cells under pre-ischemic condition (control), following ischemia induction and also reperfusion subsequent to ischemia. For the first time, flow cytometric analysis (FACS) has been used for analyzing protein expression concurrently with viability. We induced ischemia and subsequently reperfusion in 80% confluent cultures of neonatal murine cardiomyocytes (NMCC). Viability following induction was assessed with 7-AAD staining and the cells were simultaneously checked for protein expression by FACS. We observed that ischemia induction results in increased expression of CaN, Calp and Calpn. HMWCaMBP expression was reduced in live cells following ischemia which suggests that there is a poor survival outcome of cells expressing HMWCaMBP thereby making it a potential biomarker for such cells. Most live cells following ischemia expressed CaN pointing towards self-repair and favorable survival outcomes.

Tomato lycopene attenuates myocardial infarction induced by isoproterenol: electrocardiographic, biochemical and anti-apoptotic study

OBJECTIVE

To assess the protective effects of lycopene on electrocardiographic, hemodynamic, biochemical and apoptotic changes in isoproterenol induced myocardial infarction.

METHODS

Myocardial infarction was induced in rats by subcutaneous injection of isoproterenol (200 mg/kg) for two consecutive days at an interval of 24 h. Rats were treated with lycopene (10 mg/kg/day, p.o.) for a period of 30 days and isoproterenol (ISO) was injected on the 29th and 30th day. At the end of experiment i.e. on the 31st day electrocardiographic, hemodynamic, biochemical and apoptotic changes were monitored from control and experimental groups.

RESULTS

ISO injected rats showed a significant alteration in electrocardiograph pattern and hemodynamic changes (i.e. systolic, diastolic and mean arterial pressure). It also showed significant increase in C-reactive protein, myeloperoxidase, nitrite levels and Caspase-3 protease activity. In addition, it also exhibited alteration in the levels of electrolytes (Na(+), K(+) and Ca(2+)), vitamin E, uric acid and serum protein. Gel electrophoresis of ISO injected rats showed increase in DNA fragmentation. Triphenyl tetrazolium chloride staining of the heart section shows increase area of infarction in ISO injected rats. Pre-co-treatment with lycopene significantly prevented the ISO induced alteration in ECG, haemodynamic, biochemical and apoptotic changes.

CONCLUSIONS

The present result shows that treatment of lycopene in ISO injected rats significantly attenuates induced myocardial infarction.

Apocynin, a Plant-Derived Drug, Might Be Useful in the Treatment of Myocardial Ischemia Reperfusion Injury in Rat Hearts

Apocynin is a potent and selective inhibitor of the NADPH oxidase-dependent production of ROS by stimulated human PMNs. Apocynin was isolated by activity-guided isolation from Picrorhiza kurroa, and in the years following its discovery it has been used in many laboratories around the world. Reactive oxygen species (ROS) production by activated polymorphonuclear neutrophils (PMNs) plays an important role in many cardiovascular disease states, including myocardial ischemia reperfusion injury. The purpose of this study is to examine the beneficial effects of apocynin on myocardial ischemia reperfusion injury. Myocardial I/R injury was caused by clamping the left anterior descending (LAD) coronary artery for 20 min followed by release of the clamp allowing reperfusion for 1 h. Administration of apocynin i.p. (5mg/kg i.p. 10%DMSO) 15 min after ischemia significantly reduced the: 1) histological evidence of myocardial injury; 2) pro-inflammatory cytokines (TNF-α, IL-1β); 3) adhesion molecules (ICAM-1, P-Selectin); 4) nitrotyrosine formation; 5) NF-kB expression; 6) PAR formation; and 7) apoptosis (Bax, Bcl-2, Fas-L and tunel). Based on these findings we propose that apocynin would be useful in the treatment of various ischemia and reperfusion diseases.

All-trans retinoic acid alleviates hepatic ischemia/reperfusion injury by enhancing manganese superoxide dismutase in rats

All-trans retinoic acid (atRA) is an active metabolite of vitamin A with antioxidant effects. There have been few reports on the effects of atRA on liver ischemia/reperfusion (I/R) injury. Here we have used a rat liver ischemia/ reperfusion model to analyze the protective effect of atRA. Rats were administered with different does (5-15 mg/kg/d) of atRA intraperitoneally (i.p.) for 14 d before I/R. Partial (70%) hepatic ischemia was induced by clamping the hepatic artery, portal vein, and bile duct to the left and median lobes of the liver using a vascular clamp for 60 min, followed by 24 h of reperfusion. The serum aminotransferase (ALT and AST) and hepatic pathology were used to evaluate I/R injury. The results demonstrate that atRA pretreatment attenuates liver I/R injury by inhibiting the release of malondialdehyde (MDA) and by enhancing the activity of superoxide dismutase (SOD). To gain insight into the mechanism of the SOD up-regulation by atRA, the activity of p38 mitogenactivated protein kinase (p38MAKP) and Akt was measured. The results showed that the phosphorylation of p38MAPK and Akt paralleled the expression of manganese superoxide dismutase (MnSOD). That these activities are related was demonstrated by the addition of a p38 inhibitor which markedly decreased MnSOD levels. Taken together, our data reveal that atRA can protect liver from I/R injury by increaseing MnSOD, which is associated with an increased activity of p38MAPK and Akt.

Hydroxysafflor Yellow A protects spinal cords from ischemia/reperfusion injury in rabbits

Background

Hydroxysafflor Yellow A (HSYA), which is one of the most important active ingredients of the Chinese herb Carthamus tinctorius L, is widely used in the treatment of cerebrovascular and cardiovascular diseases. However, the potential protective effect of HSYA in spinal cord ischemia/reperfusion (I/R) injury is still unknown.

Methods

Thirty-nine rabbits were randomly divided into three groups: sham group, I/R group and HSYA group. All animals were sacrificed after neurological evaluation with modified Tarlov criteria at the 48th hour after reperfusion, and the spinal cord segments (L4-6) were harvested for histopathological examination, biochemical analysis and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining.

Results

Neurological outcomes in HSYA group were slightly improved compared with those in I/R group. Histopathological analysis revealed that HSYA treatment attenuated I/R induced necrosis in spinal cords. Similarly, alleviated oxidative stress was indicated by decreased malondialdehyde (MDA) level and increased superoxide dismutase (SOD) activity after HSYA treatment. Moreover, as seen from TUNEL results, HSYA also protected neurons from I/R-induced apoptosis in rabbits.

Conclusions

These findings suggest that HSYA may protect spinal cords from I/R injury by alleviating oxidative stress and reducing neuronal apoptosis in rabbits.

Bacopa monniera protects rat heart against ischaemia–reperfusion injury: role of key apoptotic regulatory proteins and enzymes

Objectives

Rat isolated hearts were perfused in a Langendorff model to study the cardioprotective effects of Bacopa monniera, a medicinal herb used in the Indian system of medicine, on cardiomyocyte apoptosis and antioxidant status following ischaemia–reperfusion (I-R) injury.

Methods

Forty-eight rats were randomly divided into four groups (12 in each group): sham group (no ischaemia–reperfusion injury), B. monniera control group (orally fed B. monniera at a dose of 75 mg/kg, for three weeks); ischaemia–reperfusion control group(subjected to ischaemia–reperfusion-induced myocardial injury) and B. monniera-treated group (same protocol as ischaemia–reperfusion control group except that rats also fed B. monniera).

Key findings

Post-ischaemic reperfusion injury resulted in significant cardiac necrosis, apoptosis, depression of heart rate, decline in antioxidant status and elevation in lipid peroxidation. Oral administration of B. monniera per se for three weeks to healthy rats caused augmentation of myocardial antioxidants, superoxide dismutase, catalase and glutathione, along with induction of heat shock protein 72 (HSP72). Ischaemia–reperfusion-induced biochemical and histopathological perturbations were significantly prevented by B. monniera (75 mg/kg) pre-treatment. Interestingly, B. monniera also restored the antioxidant network of the myocardium and reduced myocardial apoptosis, caspase 3 and Bax protein expression.

Conclusions

Histopathological studies and myocardial creatine phosphokinase content further confirmed the cardioprotective effects of B. monniera (75 mg/kg) in the experimental model of ischaemia–reperfusion injury. The study provides scientific basis for the putative therapeutic effect of B. monniera in ischaemic heart disease.

Antiapoptotic potential of herbal drugs in cardiovascular disorders: an overview

Cardiomyocyte apoptosis has been reported in a number of cardiovascular disorders, including myocardial infarction, ischemia-reperfusion, end-stage heart failure, arrhythmogenic right ventricular dysplasia, and adriamycin-induced cardiomyopathy. Prevention of myocyte apoptosis has emerged as a potential new target in a multimodel therapeutic approach to cardiac disease. Herbal therapy may be an alternative strategy for the prevention and treatment of heart disease. The present review summarizes the list of plants/herbal formulations studied for their antiapoptotic activity in cardiovascular disorders. However, despite extensive positive research data from experimental studies for herbal drugs in cardiovascular disorders, and the anecdotal clinical experience of many practitioners and patients, its potential in the field of cardiac apoptosis remains largely untapped, and large scale clinical trials are needed to explore the potential of herbal medicines as a new treatment regime for targeting cardiovascular apoptosis.

Cardioprotective effects of benazepril, an angiotensin-converting enzyme inhibitor, in an ischaemia-reperfusion model of myocardial infarction in rats

Introduction. The present study evaluated the effects of benazepril, an angiotensin-converting enzyme inhibitor on haemodynamic, biochemical, and immunohistochemical (Bax and Bcl-2 protein) indices in ischaemia and reperfusion (IR) injury.

Materials and methods. Male Wistar albino rats were divided into three groups and were orally administered saline once daily (IR-sham and IR-control) or benazepril (30 mg/kg/day; IR-benazepril) for 14 days. On the 15th day, in the IR-control and IR-benazepril groups, rats were subjected to left anterior descending coronary artery occlusion for 45 minutes followed by a one-hour reperfusion. Haemodynamic parameters were recorded and rats were sacrificed; hearts were isolated for biochemical estimation and immunohistochemistry.

Results. In the IR-control group, significant ventricular dysfunctions (p<0.05 vs. IR-sham group) were observed along with enhanced expression of pro-apoptotic protein Bax. A decline in lactate dehydrogenase activity and increased content of thiobarbituric acid reactive substances, a marker of lipid peroxidation, were observed. Benazepril pretreatment significantly improved mean arterial pressure (p<0.01), reduced left ventricular end-diastolic pressure (p<0.05), and improved both inotropic and lusitropic function of the heart (+LVdP/dt and — LVdP/dt) (p<0.05; p<0.01) as compared to IR-control. Furthermore, benazepril treatment significantly decreased the level of thiobarbituric acid reactive substances and restored the activity of lactate dehydrogenase towards normal value (p<0.05 vs. IR-control).

Conclusion. This study demonstrates that benazepril upregulated Bcl-2 protein and decreased Bax protein expression, thus exhibiting anti-apoptotic effects. These beneficial effects of benazepril will have an important implication in the therapeutic use of benazepril in ischaemic heart disease.

Comparison of the cardiac effects between quinazoline-based alpha1-adrenoceptor antagonists on occlusion-reperfusion injury

Quinazoline-based compounds such as prazosin and its congeners including doxazosin, bunazosin, and terazosin are widely used as antihypertensive agents. However, there were many clinical observations showing that using these agents may result in higher risk of cardiovascular accidents in recent years. In this study, we compared the effects of four alpha-adrenoceptor antagonists: prazosin, doxazosin, bunazosin, and terazosin on occlusion-reperfusion injury. Langendorff-perfused rat hearts were pretreated with these four antagonists, and then the left main coronary artery was occluded. After 30 min occlusion, the hearts were reperfused for 2 h and the infarct sizes were measured. Two of the compounds studied, prazosin and doxazosin, apparently increased infarct size, CK-MB, and LDH activities after 2 h reperfusion. In contrast, bunazosin decreased infarct size and those biochemical indicators of cellular damage compared to control hearts. Although infarct size after reperfusion was differently changed by these four alpha-adrenoceptor antagonists, TUNEL-positive nuclei and caspase-3 protein expressions of all the groups were not significantly different. We supposed that the different effects of these four agents on infarct size came from the difference in necrosis rather than apoptosis.

Attenuation of reperfusion lung injury and apoptosis by A2A adenosine receptor activation is associated with modulation of Bcl-2 and Bax expression and activation of extracellular signal-regulated kinases

Adenosine receptors (AR) and extracellular signal-regulated kinases (ERK) have been implicated in tissue protection and apoptosis regulation during ischemia/reperfusion (I/R) injury. This study tests the hypothesis that reduction of reperfusion lung injury after A2A AR activation is associated with attenuation of apoptosis, modulation of ERK activation, and alterations in antiapoptotic and proapoptotic protein expression (Bcl-2 and Bax, respectively). Experiments were performed in intact-chest, spontaneously breathing cats in which the arterial branch of the left lower lung lobe was occluded for 2 h and reperfused for 3 h (I/R group). Animals were treated with the selective A2A AR agonist ATL313 given 5 min before reperfusion alone or in combination with the selective A2A AR antagonist ZM241385. Western blot analysis showed significant reduction in expression of Bcl-2 and increase in expression of Bax after reperfusion, compared with control lungs. Phosphorylated ERK1/2 levels were also increased after reperfusion. Compared with the I/R group, ATL313 markedly (P < 0.01) attenuated indices of injury and apoptosis including the percentage of injured alveoli, wet-dry weight ratio, myeloperoxidase activity, in situ terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end-labeling-positive cells, and caspase 3 activity and expression. Furthermore, compared with reperfused lungs, in ATL313-pretreated lungs, Western blot analysis demonstrated substantial ERK1/2 activation, increased expression of Bcl-2, and attenuated expression of Bax. The protective effects of ATL313 were blocked by pretreatment with ZM241385. In summary, the present study shows that in vivo activation of A2A AR confers protection against reperfusion lung injury. This protection is associated with decreased apoptosis and involves ERK1/2 activation and alterations in antiapoptotic Bcl-2 and proapoptotic Bax proteins.

Impact of gradual blood flow increase on ischaemia-reperfusion injury in the rat cremaster microcirculation model

INTRODUCTION

We aimed to evaluate the impact of gradual blood reperfusion on ischaemia-reperfusion injury and to explain the pathophysiology of reperfusion injury in a rat cremaster muscle microcirculation model.

MATERIALS AND METHODS

Twenty-four Sprague-Dawley rats weighing 150-200 g were evaluated in three groups. Cremaster muscles were prepared for microcirculatory observations. Group I (n=8, control): no ischemia was induced. Group II (n=8, acute reperfusion): microclamps were applied to the right external iliac vessels for 150 min, then venous and arterial clamps were released at once. Group III (n=8, gradual reperfusion): microclamps were applied to the right external iliac vessels for 150 min, and then the first venous clamp was released; the arterial clamp was opened gradually by a specially designed microclamp holder (Sheey ossicle holding clamp). In all groups, following a wait of 150 min blood flow velocity was measured for 15 min and then the animals were reperfused freely for 1h. Next, red blood cell velocity, vessel diameters, functional capillary perfusion and endothelial oedema index were analysed, and rolling, migrating and adhesing leukocytes and lymphocytes were counted. All observations were videotaped for slow-motion replay. Muscle damage was evaluated histologically.

RESULTS

In the acute clamp release group, blood velocities increased up to 600% of their pre-ischaemic values during the post-ischaemia-reperfusion period. The numbers of rolling, adhering and transmigrating leukocytes were significantly higher and histological evaluation revealed more tissue damage in the acute reperfusion group.

CONCLUSION

Depending on histological and microcirculatory findings, gradual reperfusion was confirmed to reduce the intensity of reperfusion injury.

Tanshinone IIA protects cardiac myocytes against oxidative stress-triggered damage and apoptosis

Tanshinone IIA (tan), a derivative of phenanthrenequinone, is one of the key components of Salvia miltiorrhiza Bunge. Previous reports showed that tan inhibited the apoptosis of cultured PC12 cells induced by serum withdrawal or ethanol. However, whether tan has a cardioprotective effect against apoptosis remains unknown. In this study, we investigated the effects of tan on cardiac myocyte apoptosis induced both by in vitro incubation of neonatal rat ventricular myocytes with H(2)O(2) and by in vivo occlusion followed by reperfusion of the left anterior descending coronary artery in adult rats. In vitro, as revealed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium (MTT) assay, treatment with tan prior to H(2)O(2) exposure significantly increased cell viability. Tan also markedly inhibited H(2)O(2)-induced cardiomyocyte apoptosis, as detected by ladder-pattern fragmentation of genomic DNA, chromatin condensation, and hypodioloid DNA content. In vivo, tan significantly inhibited ischemia/reperfusion-induced cardiomyocyte apoptosis by attenuating morphological changes and reducing the percentage of terminal transferase dUTP nick end-labeling (TUNEL)-positive myocytes and caspase-3 cleavage. These effects of tan were associated with an increased ratio of Bcl-2 to Bax protein in cardiomyocytes, an elevation of serum superoxide dismutase (SOD) activity and a decrease in serum malondialdehyde (MDA) level. Taken together, these data for the first time provide convincing evidence that tan protects cardiac myocytes against oxidative stress-induced apoptosis. The in vivo protection is mediated by increased scavenging of oxygen free radicals, prevention of lipid peroxidation and upregulation of the Bcl-2/Bax ratio.

Gender specific effect of progesterone on myocardial ischemia/reperfusion injury in rats

The study was designed to investigate the effect of progesterone and its gender based variation on myocardial ischemia/reperfusion (I/R) injury in rats. Adult Sprague Dawley rats were divided into vehicle treated reperfusion injury group male (I/R-M), female (I/R-F), ovariectomised (I/R-OVR) and progesterone treatment (I/R-M+PG, I/R-F+PG, I/R-OVR+PG) groups, respectively. I/R injury was produced by occluding the left descending coronary artery (LCA) for 1 h and followed by re-opening for 1 h. Progesterone (2 mg kg(-1) i.p.) was administered 30 min after induction of ischemia. Hemodynamic parameters (+/-dp/dt, MAP), heart rate, ST-segment elevation and occurrence of ventricular tachycardia (VT) were measured during the I/R period. The myocardial infarct area, oxidative stress markers, activities of myeloperoxidase (MPO) and creatine kinase (CK) were determined after the experiment along with the assessment of the effect on apoptotic activity by using DNA fragmentation analysis. Histological observations were carried out on heart tissue. Treatment with progesterone significantly (P<0.05) reduced infarct area, lipid peroxidation (LPO) level and activity of MPO in females (I/R-F+PG) as compared to ischemic females (I/R-F). Progesterone significantly (P<0.001, P<0.05) inhibited serum CK activity and incidences of VT in female rats. Superoxide dismutase (SOD) activity, reduced glutathione (GSH) levels were significantly elevated (P<0.05) in I/R-F+PG group. Internucleosomal DNA fragmentation was less in I/R-F+PG group when compared to I/R-F group. The ischemic male and ovariectomised (I/R-M and I/R-OVR) counterparts did not show any significant change after progesterone treatment. In conclusion, the cardioprotective effect of progesterone on myocardial I/R injury induced damage is based on gender of the animal. The protective effect could be mediated by attenuation of inflammation and its possible interaction with endogenous estrogen.

Trimetazidine inhibits cardiomyocyte apoptosis in a rabbit model of ischemia-reperfusion

The effects of trimetazidine on cardiomyocyte apoptosis and hemodynamics in a rabbit model of ischemia-reperfusion were determined. Thirty male New Zealand white rabbits were randomly divided into sham, control, and treated groups (n = 10). Trimetazidine (2 mg/kg(-1)/day(-1)) was fed for 2 weeks to treated animals before the procedure. Control and treated groups were subjected to a 30-min coronary occlusion followed by a 2-h reperfusion. Mean arterial pressure, left ventricular systolic pressure, and maximum rate of left ventricular pressure rise were significantly higher in the treated group than in the controls (P < 0.01, < 0.01, and < 0.05, respectively), whereas left ventricular end-diastolic pressure was significantly lower in the treated group than in the controls (P < 0.01). As compared with the sham group, controls had a significantly higher apoptotic index (22.10% +/- 2.85% vs 0.51% +/- 0.31%, P < 0.01) and malondialdehyde (MDA) concentration (18.52 +/- 1.51 vs 5.75 +/- 0.95 micromol/, P < 0.01), and significantly lower serum superoxide dismuase (SOD) levels (66.40 +/- 7.92 vs 89.25 +/- 1.36 microU/L, P < 0.01). Trimetazidine pretreatment apparently decreased apoptotic index (11.37% +/- 2.53%, P < 0.01 vs the sham or control) and MDA concentration (5.49 +/- 0.74 micromol/L, P > 0.05 vs sham, P < 0.01 vs control), and increased SOD levels (88.81 +/- 2.81 microU/L, P > 0.05 vs sham, P < 0.01 vs control). The caspase-3 activation and mitochondrial cytochrome c release were also higher in controls than in the treated group (P < 0.01). The apoptotic indices were negatively correlated with SOD and positively correlated with MDA in the groups, suggesting that trimetazidine may be a useful drug in preventing cardiomyocyte apoptosis and ischemia-reperfusion injury.

Effects of a cantaloupe melon extract/wheat gliadin biopolymer during aortic cross-clamping

OBJECTIVE

We previously reported in healthy volunteers that a cantaloupe melon extract chemically combined with wheat gliadin (melon extract/gliadin) and containing SOD, catalase and residual glutathione peroxidase (GPx), protected against DNA strand-break damage induced by hyperbaric oxygen (HBO), a well-established model of DNA damage resulting from oxidative stress. Aortic cross-clamping is a typical example of ischemia/reperfusion injury-related oxidative stress, and therefore we investigated whether this melon extract/gliadin would also reduce DNA damage after aortic cross-clamping and reperfusion.

DESIGN

Prospective, randomized, controlled experimental study.

SETTING

Animal laboratory.

PATIENTS AND PARTICIPANTS

18 anesthetized, mechanically ventilated and instrumented pigs.

INTERVENTIONS

After 14 days of oral administration of 1250 mg of the melon extract/gliadin (n=9) or vehicle (n=9), animals underwent 30 min of thoracic aortic cross-clamping and 4 h of reperfusion.

MEASUREMENTS AND RESULTS

Before clamping, immediately before declamping, and at 2 and 4 h of reperfusion, we measured blood isoprostane (immunoassay) and malondialdehyde concentrations (fluorimetric thiobarbituric acid test), SOD, catalase and GPx activities (spectrophotometric kits), NO formation (nitrate+nitrite; chemoluminescence), DNA damage in whole blood samples and isolated lymphocytes exposed to hyperbaric oxygen (comet assay). Organ function was also evaluated. Kidney and spinal cord specimen were analysed for apoptosis (TUNEL assay). The melon extract/gliadin blunted the DNA damage, reduced spinal cord apoptosis and attenuated NO release, however, without any effect on lipid peroxidation and organ function.

CONCLUSIONS

Pre-treatment with the oral melon extract/gliadin may be a therapeutic option to reduce oxidative cell injury affiliated with aortic cross-clamping.

Radiation protects adriamycin-induced apoptosis

Combined radiotherapy and chemotherapy have represented major advance in the therapeutic management of cancer therapy. Anthracycline antineoplastic agents are limited by a high incidence of severe and usually irreversible cardiac toxicity, the cause of which remains controversial. When the primary cardiomyocytes isolated from neonatal rats were preirradiated by gamma-ray, the cells were highly resistant to adriamycin-induced apoptosis. This study shows that irradiation inhibited apoptosis by enhancing Bcl-2, attenuating Bax induction, and preventing collapse of mitochondrial membrane potential (delta psi), cytochrome c release into cytoplasm and caspase-3, -6 and -9 activations. In addition, the preirradiation stimulated the activity of manganese-superoxide dismutase (Mn-SOD) and the expression of Mn-SOD mRNA and protein. Adriamycin decreased Mn-SOD activity but did not change the activity of copper/zinc (Cu/Zn)-SOD under either pre- or nonirradiated condition. Phosphothioate-linked antisense against Mn-SOD, which specifically knocked down the activity of Mn-SOD but not that of Cu/Zn-SOD, reversed irradiation-induced protective effect in adriamycin-exposed cardiomyocytes. These data suggest that the irradiation-induced expression of Mn-SOD plays an important role in irradiation-mediated protection in adriamycin-exposed rat ventricular cardiomyocytes.