Isoproterenol-induced Myocardial Infarction In Rats Research Articles

Protective Effect of Hydroxytyrosol Against Cardiac Remodeling After Isoproterenol-Induced Myocardial Infarction in Rat.

The present study aimed to investigate the cardioprotective effect of hydroxytyrosol (HT) against isoproterenol-induced myocardial infarction in rats. Male rats were randomly divided into four groups, control, isoproterenol (Isop) and pretreated animals with HT in two different doses (2 and 5mg/kg) orally for 7days and intoxicated with isoproterenol (Isop+HT1) and (Isop+HT2) groups. Myocardial infarction in rats was induced subcutaneously by isoproterenol (100mg/kg, s.c.) at an interval of 24h on 6th and 7th day. On 8th day, electrocardiographic (ECG) pattern, gravimetric and biochemical parameters were assessed. Isoproterenol exhibited changes in ECG pattern, including significant ST-segment elevation and increase in the serum troponin-T level by 317% as compared to control rats. Moreover, cardiac injury markers (creatine kinase-MB, lactate dehydrogenase, alanine aminotransferase) underwent a notable rise in serum of infarcted animals. Else, a disturbance in lipids profile and significant increase in lipase and angiotensin-converting enzyme (ACE) activities and heart weight ratio were observed in isoproterenol group. However, pre- and co-treatment with HT (2 and 5mg/kg) improved the myocardium injury, restored the hemodynamic function and inhibited the ACE activity that prevent cardiac hypertrophy and remodeling. Overall, these findings demonstrated that HT exerted a potent cardioprotective effect against isoproterenol-induced myocardial infarction.

Antihyperlipidaemic, antihypertrophic, and reducing effects of zingerone on experimentally induced myocardial infarcted rats.

The present study aims to evaluate the antihyperlipidaemic, antihypertrophic, and reducing effects of zingerone on isoproterenol-induced hyperlipidaemia and hypertrophy in rats. Rats were pretreated with zingerone (6 mg/kg body weight) daily for a period of 14 days and then induced myocardial infarction with isoproterenol (100 mg/kg body weight) on days 15 and 16. Isoproterenol increased serum creatine kinase and lactate dehydrogenase activities in the rats. Increased levels/concentrations of serum and heart cholesterol and triglycerides were observed in isoproterenol-induced myocardial infarcted rats. Isoproterenol also altered serum lipoproteins and the activity of liver 3-hydroxy-3-methyl glutaryl-coenzyme-A-reductase in the rats. The in vitro study revealed a very convincing reducing power of zingerone. Pretreatment with zingerone prevented hyperlipidaemia and cardiac hypertrophy, by virtue of its antihyperlipidaemic, antihypertrophic, and reducing properties in isoproterenol-induced myocardial infarcted rats.

Cardioprotective Effects of Essential Oil of Lavandula angustifolia on Isoproterenol-induced Acute Myocardial Infarction in Rat.

Myocardial infarction (MI) is a common presentation of the ischemic heart disease. Lavandula angustifolia is an herbaceous plant with antioxidative effects. This study was designed to investigate the cardioprotective effects of lavandula angustifolia essential oil against isoproterenol-induced MI in rats. The dried sample was subjected to hydrodistillation by using a Clevenger and the oils were dried over anhydrous Na2SO4. Male Wistar rats were assigned to 6 groups of control, sham, isoproterenol and treatment with 5, 10, 20 mg/Kg of the essential oil. MI was induced by subcutaneous injection of Isoproterenol (100 mg/Kg) for 3 consecutive days at an interval of 24 h. The essential oil was given intraperitoneally every 24 h started at MI induction. Following anesthesia, hemodynamic parameters were measured. After sacrificing the animals, the hearts were removed to measure the heart to body weight ratio and histopathological examination. Myeloperoxidase (MPO) and Malondialdehyde (MDA) were measured in heart tissues for evaluating the activity of neutrophils and lipid peroxidation, respectively. The essential oil amended ECG pattern by suppressing ST-segment elevation and increasing R-amplitude. 10 mg/Kg of the essential oil significantly decreased heart to body weight ratio (P<0.001) and the elevation of MDA and MPO in myocardium, it also increased dp/dtmax from 2793 ± 210 to 4488 ± 253 mmHg/sec (P<0.001), and 20 mg/Kg of it significantly lowered LVEDP from 14 ± 3.43 to 4.3 ± 0.83 mmHg (P<0.001).The results demonstrated that L. angustifolia protects myocardium against isoproterenol-induced MI that it could be related to its antioxidant properties.

Cardioprotective Effect of Hydrogen-rich Saline on Isoproterenol-induced Myocardial Infarction in Rats

Infusion with hydrogen gas-saturated saline has recently been reported to exert antioxidant and anti-inflammatory activity that may protect against organ damage induced by oxidative stress. Therefore because oxidative stress plays a significant role in the pathophysiology of myocardial infarction (MI), the aim of our study was to investigate whether hydrogen-rich saline has cardioprotective effects against isoproterenol-induced MI in rats. An acute MI model was induced in male Wistar rats by subcutaneous injection of isoproterenol. Different doses of hydrogen-rich saline (5, 7.5, and 10 mL/kg body weight i.p.) or Vitamin C (250 mg/kg body weight i.g.) were administered to the rats. Oxidative stress indices including levels of myocardial marker enzymes, inflammatory cytokines, membrane-bound myocardial enzymes and histopathological changes were measured. Compared with those in isoproterenol-MI group, hydrogen-rich saline decreased malondialdehyde and 8-hydroxy-desoxyguanosine concentrations, enhanced superoxide dismutase and Na(+)-K(+)-ATPase activity, lowered Ca(2+)-ATPase activity and decreased interleukin-6 and tumour necrosis factor-α levels in the serum and/or cardiac tissue of rats. Hydrogen-rich saline pretreatment also diminished infarct size, improved left heart function, and ameliorated pathological changes of the left heart. From these results, hydrogen-rich saline exerts cardiovascular protective effects against isoproterenol-induced MI at least in part via interactions which evoke antioxidant and anti-inflammatory activities.

Benidipine prevents oxidative stress, inflammatory changes and apoptosis related myofibril damage in isoproterenol-induced myocardial infarction in rats

Objective: The effects of benidipine on oxidative stress and myocardial apoptosis were assessed in isoproterenol (ISO)-induced myocardial infarction (MI) in wistar rats.Materials and method: Animals were pretreated with benidipine (1, 3, 10 μg/kg/day Body weight) intravenously for a period of 28 days. After pretreatment, ISO (85 mg/kg Body weight, subcutaneous) was injected in rats at an interval of 24 h to induce MI. Myocardial oxidative stress, cardiac biomarkers, apoptosis, inflammatory mediators, and ultrastructural architecture of the cardiac tissue were assessed in ISO-induced MI in rats.Result: Significant variation in the level of TBA, antioxidant enzymes (GSH, CAT, SOD, GPx, GRx, GST) in myocardium, cardiac biomarkers (CK-MB, LDH) in serum, Caspase-3, C-reactive protein (CRP), and alteration in ultrastructural architecture of cardiac tissue confirmed the cardiotoxicity induced by ISO. Pretreatment with benidipine preserved the lipid peroxide and antioxidant enzymes, and furthermore showed maintained levels of myocardial biomarker, CRP and caspase-3. Ultrastructure architecture of cardiac tissue was also found to be well preserved.Conclusion: The present study suggested cardioprotective effect of benidipine which may possibly be due to its antioxidant activity and antiapoptotic nature.

GW25-e4168 Dipeptidyl peptidase (DPP) -4 inhibitor exhibits anti-apoptosis effects in isoproterenol-induced myocardial infarcted rats by inhibiting oxidative stress

Cardiac apoptosis plays an important role in the pathology of myocardial infarction. The protective effects of Dipeptidyl peptidase (DPP) -4 inhibitor (vildagliptin) on cardiac apoptosis were evaluated in isoproterenol induced myocardial infarcted rats. Male Wistar rats are treated intravenously

Preventive effects of zingerone on altered lipid peroxides and nonenzymatic antioxidants in the circulation of isoproterenol-induced myocardial infarcted rats.

The present study was designed to evaluate the preventive effects of zingerone on circulatory lipid peroxides and nonenzymatic antioxidants in isoproterenol-induced myocardial infarcted rats. Rats were pretreated with zingerone (6 mg/kg body weight) daily for a period of 14 days and were then induced myocardial infarction with isoproterenol (100 mg/kg body weight) on 15th and 16th day. Increased intensities of serum lactate dehydrogenase isoenzymes 1 and 2 bands enhanced plasma lipid peroxidation products and lowered nonenzymatic antioxidant system were noted in isoproterenol-induced rats. Pretreatment with zingerone daily for 14 days revealed significant preventive effects on the electrophoretic and biochemical parameters evaluated in isoproterenol-induced rats. Furthermore, the in vitro study confirmed the potent antioxidant activity of zingerone. The results of our study showed that zingerone protected the rat's heart against isoproterenol-induced myocardial infarction by its antioxidant effect.

Effects of LDL and Oxidized LDL on Cardiac Function in Isoproterenol-induced Myocardial Infarction in Rat

Notable discussions have been developed over the distinctive effects of LDL and oxidized LDL (OxLDL) on myocardial functions. The aim of the present study was to investigate the effects of OxLDL on electrocardiogram and hemodynamic parameters of rat's heart in isoproterenol (ISO)-induced myocardial infarction (MI) model.Male Wistar rats were allocated in to 6 groups and receive one of the 3 formulated diets (standard, cholesterol-rich and oxidized cholesterol-rich diets). After 14 weeks to induce MI, rats in 3 groups were received ISO (100 mg/kg) for 2 consecutive days subcutaneously. Lipid profiles, electrocardiogram patterns and hemodynamic parameters of all groups were investigated.Serum levels of LDL, cholesterol and triglycerides were significantly higher in the fat-rich diet fed groups compared to control group (P<0.001). The ISO-treated rats showed a marked reduction in the R-amplitude, R-R interval, LVSP, left ventricular contractility (LVdP/dtmax) and relaxation (LVdP/dtmin) as well as severe elevation in ST-segment and LVEDP value compared to the respective normal rats. High serum level of OxLDL resulted in significant exacerbation in the destructive effects of ISO on R-amplitude, R-R interval, LVSP, left ventricular contractility (LVdP/dtmax), relaxation (LVdP/dtmin), ST-segment and LVEDP values. Additionally, heart to body weight ratio as an index of myocardial edematous was also increased significantly. However, changes in these parameters in rats fed with cholesterol-rich diet were not significant.Generally, results indicated that the effects of high OxLDL level on electrocardiogram and hemodynamic parameter after MI was more reliable than effects of high LDL level.

Diosmin exhibits anti-hyperlipidemic effects in isoproterenol induced myocardial infarcted rats

The aim of the present study was to evaluate the protective effects of diosmin on experimentally induced myocardial infarcted rats. Diosmin (5 and 10mg/kg body weight) was administered orally as pretreatment daily for a period of 10 days. Then isoproterenol (100mg/kg) was injected subcutaneously into rats at an interval of 24h for 2 days (on 11th and 12th day). Isoproterenol-induced myocardial infarcted rats showed significant changes in electrocardiogram and an increase in the levels of cardiac markers, compared with normal rats. Additionally, increased plasma lipid peroxidation products and altered lipid metabolism in the plasma were observed in the isoproterenol-induced myocardial infarcted rats. Pretreatment with diosmin (5 and 10mg/kg body weight) minimized the electrocardiographic changes, decreased the levels of serum cardiac marker enzymes reduced plasma lipid peroxidation and minimized the alterations in the lipid metabolism of isoproterenol-induced myocardial infarcted rats. Also, diosmin inhibited the enhanced activity of liver HMG CoA reductase. The in vitro study revealed the free radical scavenging activity of diosmin. The free radical scavenging and anti-hyperlipidaemic effects are the reasons for the cardioprotective effects of diosmin.

Coconut kernel protein in diet protects the heart by beneficially modulating endothelial nitric oxide synthase, tumor necrosis factor-alpha, and nuclear factor-kappaB expressions in experimental myocardial infarction

Previous studies conducted in our laboratory revealed that coconut kernel protein has a significant cardioprotective effect on isoproterenol-induced myocardial infarction in rats. In the present study, we explored the possible protective mechanism of coconut kernel protein during acute myocardial infarction. Coconut kernel protein (50 mg/100 g) was administered to Sprague-Dawley rats orally for 45 days. Isoproterenol (20 mg/100 g) was injected subcutaneously at an interval of 24 hours twice to induce myocardial infarction. Myocardial infarction was confirmed by the abnormal activities of cardiac marker enzymes in serum. Activities of antioxidant enzymes such as superoxide dismutase (SOD) and catalase were decreased (p < 0.05) in the heart of isoproterenol-treated rats, whereas pretreatment with coconut kernel protein increased (p < 0.05) these activities. An improved antioxidant status in these rats was further confirmed by the increased level of reduced glutathione and decreased level of lipid peroxidation products. Nitric oxide synthase (NOS) activity in the heart and nitrite level in blood were increased (p < 0.05) in coconut kernel protein-treated rats administered with isoproterenol compared to isoproterenol control rats. Coconut protein pretreatment upregulated the expression of endothelial nitric oxide synthase (eNOS), whereas expressions of nuclear factor-kappaB (NF-κB) and tumor necrosis factor-alpha (TNF-α) were downregulated in isoproterenol-treated rats. These findings suggest that the protective effects of coconut kernel protein may be mediated in part through upregulation of nitric oxide production, antioxidant mechanisms, and its ability to inhibit TNF-α and NF-κB activation.

Regulation of antioxidant system, lipids and fatty acid β-oxidation contributes to the cardioprotective effect of sodium tanshinone IIA sulphonate in isoproterenol-induced myocardial infarction in rats

ObjectiveMyocardial infarction (MI) is a cause of high morbidity and mortality in the world. Sodium tanshinone IIA sulphonate (STS) has been well used in Oriental medicine for treating cardiovascular diseases, however, the underlying mechanisms remain unclear. Alterations of circulating lipid profiles, increased fatty acid β-oxidation and oxidative stress play most important roles in the pathogenesis of MI. The present study aims to elucidate whether STS possesses cardioprotective effect against MI driven by isoproterenol (ISO), and to investigate its potential mechanisms of action. MethodsMI was induced by subcutaneous injection of ISO (85 mg/kg at interval of 24 h for 2 consecutive days) to rats. The rats were randomly divided into 6 groups: (1) control; (2) ISO; (3) STS (16 mg/kg) +control; (4–6) STS (16, 8, 4 mg/kg) +ISO. ResultsOur study showed that STS could ameliorate cardiac dysfunction and variation of myocardial zymogram, up-regulate antioxidant systems, and maintain the levels of circulating lipids driven by supramaximal doses ISO as well. Moreover, modulation of redox-sensitive extracellular signal-regulated kinase1/2 (ERK1/2)/Nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) and AMP-activated protein kinase (AMPK)/acetyl CoA carboxylase (ACC)/carnitine palmitoyltransferase (CPT) 1 pathways were involved in STS induced cardioprotection. ConclusionsSTS exerts strong favorable cardioprotective action. Additionally, the properties of STS, such as anti-dyslipidemia, anti-oxidant and inhibition of fatty acid β-oxidation, may be the mechanisms underlying the observed results.

P-Coumaric acid attenuates apoptosis in isoproterenol-induced myocardial infarcted rats by inhibiting oxidative stress

Cardiac apoptosis plays an important role in the pathology of myocardial infarction. The protective effects of p-coumaric acid on cardiac apoptosis were evaluated in isoproterenol induced myocardial infarcted rats. Rats were pretreated with p-coumaric acid (8 mg/kg body weight) daily for a period of 7 days. After pretreatment, isoproterenol (100 mg/kg body weight) was injected subcutaneously into rats at an interval of 24 h for 2 days to induce myocardial infarction. Cardiac diagnostic markers, heart lipid peroxidation, antioxidant system, histopathological changes of the heart and apoptosis were evaluated in isoproterenol induced myocardial infarcted rats. Isoproterenol induced myocardial infarcted rats showed a significant increase in the levels of serum cardiac diagnostic markers, heart lipid peroxidation products and a significant decrease in the activities/levels of heart antioxidants. Histopathological findings of myocardial infarcted rats revealed marked necrosis and edema. Reverse Transcription Polymerase Chain Reaction study revealed an increase in the myocardial expression of Bax, caspase-8, caspase-9 and Fas genes and a decrease in the myocardial expression of Bcl-2 and Bcl-xL genes. p-Coumaric acid pretreatment showed protective effects on apoptosis by inhibiting oxidative stress. p-Coumaric acid pretreated isoproterenol induced myocardial infarcted heart also confirmed these findings. The possible mechanisms for the protective effects of p-coumaric acid could be attributed to antilipid peroxidative, antioxidant and antiapoptotic properties. Thus, p-coumaric acid protected the myocardial infarcted rat's heart against apoptosis by inhibiting oxidative stress.

Luteolin a dietary flavonoid attenuates isoproterenol-induced myocardial oxidative stress in rat myocardium: An in vivo study

Aim of the present study, an attempt has been made in acute and chronic periods after isoproterenol (ISO)-induced myocardial infarction (MI) in male Wistar rats. Luteolin supplimentated by intragastric intubation at a daily dose of 0.3mg/kg body weight in acute and chronic periods following MI. In acute MI model, luteolin had been administered once per day to rat groups during 30 days. On 29th and 30th day, the rats of the acute MI control groups were administered 85mg/kg body weight, isoproterenol, intraperitoneally intravel of 24h. In chronic MI model, luteolin supplimentated of rat group during 30 days. On the 1st and 2nd days, the rats of the chronic MI control and luteolin treatment groups were administered ISO by the same way. The ISO-induced rats both in acute and chronic models showed decrease in the levels of heart phospholipids and increased levels of cholesterol, triglycerides, free fatty acids and phospholipids in serum and heart, and also significantly increase in the activities of cardiac marker enzymes like Troponin I and T, CK, CK-MB, LDH, AST and ALT. Oral treatment with luteolin at a daily dose of (0.3mg/kg body weight) in both acute and chronic models showed significantly decrease in the levels of heart and serum lipid metabolism products and significant decrease in the levels of marker enzymes. The study results revealed that luteolin ameliorates cardiac damage in ISO-induced myocardial infarction by maintaining lipids levels by its antilipidemic effects in isoproterenol-induced myocardial infarcted rats.

(−) Epicatechin prevents alterations in lysosomal glycohydrolases, cathepsins and reduces myocardial infarct size in isoproterenol-induced myocardial infarcted rats

The preventive effects of (−) epicatechin on oxidative stress, cardiac mitochondrial damage, altered membrane bound adenosine triphosphatases and minerals were reported previously in isoproterenol-induced myocardial infarction model. Leakage of lysosomal glycohydrolases and cathepsins play an important role in the pathology of myocardial infarction. This study was aimed to evaluate the preventive effects of (−) epicatechin on alterations in lysosomal glycohydrolases, cathepsins and myocardial infarct size in isoproterenol-induced myocardial infarcted rats. Male albino Wistar rats were pretreated with (−) epicatechin (20mg/kg body weight) daily for a period of 21 days. After the pretreatment period, isoproterenol (100mg/kg body weight) was injected subcutaneously into the rats at an interval of 24h for two days to induce myocardial infarction. The levels of serum cardiac troponin-I and the activities of serum and heart lysosomal enzymes (β-glucuronidase, β-N-acetyl glucosaminidase, β-galactosidase, cathepsin-B and cathepsin-D) were increased significantly (P<0.05) and the activities of β-glucuronidase and cathepsin-D in the heart lysosomal fractions were significantly (P<0.05) decreased in isoproterenol-induced myocardial infarcted rats. The in vitro study revealed the potent antioxidant action of (−) epicatechin. Pretreatment with (−) epicatechin daily for a period of 21 days prevented the leakage of cardiac marker, lysosomal glycohydrolases, cathepsins, and reduced infarct size, thereby protecting the lysosomal membranes in isoproterenol-induced myocardial infarcted rats, by virtue of its membrane stabilizing property.

Effects of Rosiglitazone on Isoproterenol-induced Myocardial Infarction in Rats

Effects of Rosiglitazone on Isoproterenol-induced Myocardial Infarction in Rats

Preventive Effects of (–) Epicatechin on Altered Adenosine Triphosphatases and Minerals in Isoproterenol‐Induced Myocardial Infarcted Rats

The present study was aimed to evaluate the preventive effects of (-) epicatechin on alterations in the activities/levels of adenosine triphosphatases and minerals in isoproterenol-induced myocardial infarcted rats. Male albino Wistar rats were pretreated with (-) epicatechin (20 mg/kg body weight) daily for a period of 21 days. After the pretreatment period, rats were induced myocardial infarction by isoproterenol (100 mg/kg body weight) on 22nd and 23rd day. The activity of sodium/potassium-dependent adenosine triphosphatase was decreased, and the activities of calcium- and magnesium-dependent adenosine triphosphatases were increased in the heart of isoproterenol-induced myocardial infarcted rats. In addition, the concentrations of potassium were decreased and the concentrations of sodium and calcium were increased in the heart of isoproterenol-induced rats. Elevated plasma lipid peroxidation was noted in isoproterenol-induced rats. Prior treatment with (-) epicatechin significantly prevented the alterations in the activities and concentrations of adenosine triphosphatases, minerals, and plasma lipid peroxidation. The in vitro study confirmed the reducing property of (-) epicatechin. The observed effects in this study are attributed to the membrane-stabilizing and antioxidant properties of (-) epicatechin. The findings of this study will be beneficial to prevent the occurrence of myocardial infarction.

Protective effects of sinapic acid on cardiac hypertrophy, dyslipidaemia and altered electrocardiogram in isoproterenol-induced myocardial infarcted rats

Lipids and lipoproteins play a vital role in the pathogenesis of myocardial infarction. There are no studies reported on the protective effects of sinapic acid on changes in electrocardiogram, lipids and lipoproteins in myocardial infarction. This study aims to evaluate the protective effects of sinapic acid on cardiac hypertrophy, dyslipidaemia and alterations in lipoproteins and electrocardiogram in isoproterenol-induced myocardial infarcted rats. Rats were pre- and co-treated with sinapic acid (12mg/kg body weight) daily for a period of 10 days and were induced myocardial infarction with isoproterenol (100mg/kg body weight) on 9th and 10th day. Isoproterenol induced rats showed an increased level of serum cardiac troponin-T and elevated ST-segments. Increased levels of serum and heart cholesterol, triglycerides and free fatty acids were observed in isoproterenol induced rats. Isoproterenol also increased serum low density and very low density lipoprotein cholesterol and decreased high density lipoprotein cholesterol. The activity of liver 3-hydroxy-3-methyl glutaryl-coenzyme-A-reductase was elevated in isoproterenol induced rats. The in vitro study revealed the potent antioxidant activity of sinapic acid. Pre- and co-treatment with sinapic acid ameliorated cardiac hypertrophy, dyslipidemia and elevated ST-segments in isoproterenol induced myocardial infarcted rats. Thus, sinapic acid prevented the alterations in the levels of lipids and lipoproteins by virtue of its antilipidaemic effect in isoproterenol induced myocardial infarcted rats.

Cardioprotective Effect of Paeonol and Danshensu Combination on Isoproterenol-Induced Myocardial Injury in Rats

BackgroundTraditional Chinese medicinal herbs Cortex Moutan and Radix Salviae Milthiorrhizaeare are prescribed together for their putative cardioprotective effects in clinical practice. However, the rationale of the combined use remains unclear. The present study was designed to investigate the cardioprotective effects of paeonol and danshensu (representative active ingredient of Cortex Moutan and Radix Salviae Milthiorrhizae, respectively) on isoproterenol-induced myocardial infarction in rats and its underlying mechanisms.MethodologyPaeonol (80 mg kg−1) and danshensu (160 mg kg−1) were administered orally to Sprague Dawley rats in individual or in combination for 21 days. At the end of this period, rats were administered isoproterenol (85 mg kg−1) subcutaneously to induce myocardial injury. After induction, rats were anaesthetized with pentobarbital sodium (35 mg kg−1) to record electrocardiogram, then sacrificed and biochemical assays of the heart tissues were performed.Principal FindingsInduction of rats with isoproterenol resulted in a marked (P<0.001) elevation in ST-segment, infarct size, level of serum marker enzymes (CK-MB, LDH, AST and ALT), cTnI, TBARS, protein expression of Bax and Caspase-3 and a significant decrease in the activities of endogenous antioxidants (SOD, CAT, GPx, GR, and GST) and protein expression of Bcl-2. Pretreatment with paeonol and danshensu combination showed a significant (P<0.001) decrease in ST-segment elevation, infarct size, cTnI, TBARS, protein expression of Bax and Caspase-3 and a significant increase in the activities of endogenous antioxidants and protein expression of Bcl-2 and Nrf2 when compared with individual treated groups.Conclusions/SignificanceThis study demonstrates the cardioprotective effect of paeonol and danshensu combination on isoproterenol-induced myocardial infarction in rats. The mechanism might be associated with the enhancement of antioxidant defense system through activating of Nrf2 signaling and anti-apoptosis through regulating Bax, Bcl-2 and Caspase-3. It could provide experimental evidence to support the rationality of combinatorial use of traditional Chinese medicine in clinical practice.

Short-term treatment with metformin suppresses toll like receptors (TLRs) activity in isoproterenol-induced myocardial infarction in rat: Are AMPK and TLRs connected?

AMP-activated protein kinase (AMPK) is a key sensor of cellular energy. The activation of AMPK by metformin prevents cardiac remodeling after myocardial infarction (MI). Besides, the innate immune response through TLRs is activated during MI. In the present study, the effects of short-term treatment with metformin on TLRs activity and its relation with AMPK in isoproterenol-induced MI were assessed in rats. To induce MI, a subcutaneous injection of isoproterenol was given to Wistar rats for two consecutive days. Metformin (25, 50, and 100mg/kg) was orally administered to rats twice daily for two days. Interstitial fibrosis was dose-dependently attenuated in the treated groups in comparison to the MI group (score: 1.25±0.28 with 100mg/kg metformin versus 3.5±0.28; P<0.001). Further, metformin reduced TLR-dependent inflammatory cytokines as indexed by reduced myocardial levels of TNFα (maximum 68%; P<0.001) and IL6 (maximum 84%; P<0.001) as well as by reduced myocardial MPO activity (25%; P<0.01). It was found that the level of phosphorylated AMPK was significantly upregulated by 165% (P<0.001) when treated with 100mg/kg of metformin, but not with 25 and 50mg/kg. This was associated with a remarkable suppression of TLR4 expression and reduction of protein level of TLRs adapter protein, MyD88 (P<0.01) in the infarcted myocardium. These results suggest that AMPK activation by metformin and the subsequent suppression of TLRs activity could be considered as a target in protecting the infarcted heart, which may indicate a link between AMPK and TLRs.

Cardioprotective effect of lycopene against isoproterenol-induced myocardial infarction in rats

The present study was designed to evaluate the cardioprotective potential of lycopene (LCP) against isoproterenol (ISP)-induced myocardial infarction (MI), by assessing hemodynamic, biochemical and histopathological parameters. Wistar male albino rats were orally administered with LCP (0.5, 1.0 and 1.5 mg/kg) or with vehicle for 30 days, with concurrent subcutaneous injections of ISP (85 mg/kg) on days 28 and 29. ISP significantly (p < 0.05) decreased systolic, diastolic and mean arterial blood pressure (SAP, DAP and MAP, respectively) and heart rate (HR). ISP also decreased contractility (+LVdP/dt), relaxation (-LVdP/dt) and increased left ventricular end-diastolic pressure (LVEDP). In addition to functional impairment, ISP also caused a significant (p < 0.05) decrease in antioxidants, namely, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx), glutathione (GSH), cardiac injury marker enzymes, creatine phosphokinase-MB (CK-MB) and lactate dehydrogenase (LDH), as well as induced lipid peroxidation, malonaldialdehyde (MDA) and histopathological alterations in heart. However, pretreatment with LCP significantly (p < 0.05) attenuated ISP-induced cardiac dysfunction as evidenced by improved SAP, DAP, MAP, HR, (±)LVdP/dt and reduced LVEDP. Pretreatment with LCP also significantly (p < 0.05) prevented the depletion of antioxidants (SOD, CAT, GSHPx and GSH), myocyte injury marker enzymes (CK-MB and LDH) and inhibited lipid peroxidation and MDA formation in the heart. Furthermore, reduced necrosis, edema and infiltration of inflammatory cells on histopathological examination also depicted the protective effect of LCP against the deleterious effect of ISP. Based on the results, it is suggested that LCP possesses significant cardioprotective potential and may serve as an adjunct in treatment and prophylaxis of MI.