Myocardial Superoxide Dismutase Activity Research Articles

The Effect of Eugenol Treatment on Diabetic Cardiomyopathy in Streptozotocin-Induced Diabetic Rats

Cardiovascular diseases account for most of the morbidity and mortality associated with diabetes. Diabetic cardiomyopathy (DCM) is associated with heart failure in diabetic patients without relation to other cardiovascular diseases such as hypertension or coronary artery disorders. Eugenol is a phenolic compound extracted from the clove tree and exhibits effective mitigation of hyperglycemic conditions in diabetic animals. Thus, in the current study, we aimed to explore the effect of eugenol treatment on rats with DCM. The experimental animals included 30 Sprague Dawley male rats which are divided into three experimental groups (10 rats each) as the following: the non-diabetic control group (ND), diabetic group (D), and a treated-diabetic group (20mg/kg/day of eugenol) (D+E). Diabetes was induced by streptozotocin (STZ) injection (60 mg/ kg). After 6 weeks, blood samples and left ventricles were collected for analysis. Serum glucose levels, heart weight/body weight ratio, and the myocardial mRNA expression of transforming growth factor β1 (TGF-β1), tumor necrosis factor-α (TNF-α), caspase 3 (casp3), vascular endothelial growth factor-A (VEGF-A), and collagen IV were evaluated. Furthermore, the myocardial superoxide dismutase (SOD) activity was measured. Diabetic rats showed a significant appearance of hyperglycemia and increased expression of myocardial TNF-α, TGF-β1, caspase 3, and VEGF-A compared to the control group (P < 0.05), and a tendency to increase collagen IV (P < 0.1). On the other hand, the eugenol treatment mitigates diabetic-associated hyperglycemia and the increased mRNA expression levels of myocardial TGF-β1, VEGF-A, caspase 3, and TNF-α (P < 0.05). In addition, the overexpression of collagen IV was inhibited, and the myocardial SOD activity was improved in the diabetic rats treated with eugenol. The study provided evidence that eugenol may have a potential therapeutic effect in the experimental models of DCM by reducing the expression of pro-inflammatory, pro-fibrotic, angiogenic, and pro-apoptotic factors (TNF-α, TGF-β, collagen IV, VEGF-A, and caspase 3 respectively). It is recommended for further studies investigate the exact molecular processes by which eugenol may ameliorate the DCM phenotype.

Effect of swimming training on the expression of PKC δ/p66Shc protein in mouse myocardium

Objective: To investigate the effects of different intensity of swimming training on p66Shc protein in mouse myocardium. Methods: Fifty Kunming mice were randomly divided into control group (Group C), weight-bearing swimming group (Group E), weight-bearing swimming + drug group (Group ER), non weight-bearing swimming group (Group P), non weight-bearing swimming + drug group (Group PR), with 10 mice in each group. Group C did not exercise. Groups E, ER, P, and PR received swimming training for 4 weeks. Groups E and ER performed weight-bearing swimming with a 3% body weight, and Group P and Group PR were swimming without weight-bearing, 60 min/d, 6 times/w. Mice in ER and PR groups were injected intraperitoneally with Rottlerin (0.3 mg/kg), a PKCδ inhibitor, before the last two exercises. Groups C, E, and P were injected with the same dose of normal saline. Samples were collected after training finished for 24 hours. The protein expressions of PKCδ, P-PKCδ, P66Shc, P-P66shc and NOX2 were detected by Western blot; PKCδ and P66Shc were detected by immunoprecipitation; malondialdehyde (MDA), reactive oxygen species (ROS) and superoxide dismutase (SOD) in myocardium and serum were analyzed by biochemistry. Results: Compared with Group C, the protein expressions of PKCδ, P-PKCδ, P66Shc, P-P66shc and NOX2 in Group E were increased significantly (P＜ 0.01), the serum and myocardial MDA levels, myocardial ROS were increased significantly (P＜0.05 or P＜0.01), and the myocardial SOD activity was decreased (P＜0.01), the PKCδ, P-PKCδ, P-P66shc and NOX2 in Group P were increased significantly (P＜0.05 or P＜0.01), and the myocardial SOD activity was enhanced (P＜0.05). Compared with Group E, the protein expressionS of PKCδ (P＜0.01), P-PKCδ (P＜0.01), P66Shc (P＜0.05), P-P66shc (P＜0.01), NOX2 (P＜0.05) in Group ER was decreased significantly, the protein expression of P66Shc in Group P was decreased significantly (P＜0.05), the myocardial MDA (P＜0.01) and ROS (P＜0.05) were decreased, and the activity of SOD was enhanced (P＜0.01). Compared with Group P, the protein expressions of PKCδ, P-PKCδ and P-P66shc in Group PR were decreased significantly (P＜0.01), while the expression of NOX2 was increased (P＜0.05). Conclusion: Both swimming training of two intensities promoted the increase of PKCδ protein and its phosphorylation in mouse cardiomyocytes. High-intensity swimming training could significantly enhance the expression and phosphorylation level of p66Shc protein, resulting in the production of ROS and the decrease of antioxidant enzyme activity. Low-intensity swimming training enhanced the phosphorylation of p66Shc, but did not promote its protein expression, resulting in the enhancement of myocardial antioxidant capacity and exercise adaptation.

Schisandra chinensis bee pollen\u2019s chemical profiles and protective effect against H2O2-induced apoptosis in H9c2 cardiomyocytes

BackgroundSchisandra chinensis (Turcz.) Baill bee pollen extract (SCBPE) is often used as a functional food in China due to its good antioxidant property. However, its chemical compositions and effects on H9c2 cardiomyocytes against H2O2-induced cell injury still lacks of reports thus far. This study aimed to characterize the main components of SCBPE and investigate its protective effects against H2O2-induced H9c2 cardiomyocyte injury.MethodsThe main components of SCBPE were analyzed via ultraperformance liquid chromatography–quadrupole time-of-flight tandem mass spectrometry (UPLC–QTOF MS/MS). The three main nucleosides in SCBPE were quantitatively analyzed via ultraperformance liquid chromatography–diode array detection. Furthermore, the potential mechanism by which SCBPE exerts protective effects against H2O2-induced H9c2 cardiomyocyte injury was explored for the first time via cell survival rate measurements; cell morphological observation; myocardial superoxide dismutase (SOD) activity and malondialdehyde (MDA) and glutathione (GSH) level determination; flow cytometry; and quantitative polymerase chain reaction.ResultsTwo carbohydrates, three nucleosides, and nine quinic acid nitrogen-containing derivatives in SCBPE were identified or tentatively characterized via UPLC–QTOF MS/MS. The nine quinic acid nitrogen-containing derivatives were first reported in bee pollen. The contents of uridine, guanosine, and adenosine were 2.4945 ± 0.0185, 0.1896 ± 0.0049, and 1.8418 ± 0.0157 μg/mg, respectively. Results of in vitro experiments showed that cell survival rate, myocardial SOD activity, and GSH level significantly increased and myocardial MDA level significantly decreased in SCBPE groups compared with those in H2O2 group. Cell morphology in SCBPE groups also markedly improved compared with that in H2O2 group. Results indicated that SCBPE protected H9c2 cardiomyocytes from H2O2-induced apoptosis by downregulating the mRNA expressions of Bax, cytochrome C, and caspase-3 and upregulating the Bcl-2 mRNA expression.ConclusionsThis study is the first to report that SCBPE could protect against oxidative stress injury and apoptosis in H2O2-injured H9c2 cells. Results indicated that the nucleosides and quinic acid nitrogen-containing derivatives could be the main substances that exert protective effects against H2O2-induced H9c2 cardiomyocyte injury.

Research of the heart protective effect of exercise precondition mediated by calcitonin gene related peptide on acute exhaustion rats

To observe the heart protective effect of exercise preconditioning (EP) in the acute exhaustion exercise (EE) rats, and explore its action mechanism further. Eighty healthy male Sprague-Dawley (SD) rats were divided into control group (C group), EP group, EE group, and EP+EE group randomly, with 20 rats in each group. The rats in EP and EP+EE groups were trained for 3 weeks according to the daily swimming for 60 minutes (swimming 15 minutes, resting 5 minutes, repeating 3 times) with 6 days each week. The rats in EE and EP+EE groups on the last 1 day after 3 weeks, 3% weight heavy weight was carried once for swimming EE. Two hours after the last EE, abdominal aortic blood and heart was harvested, the levels of serum MB isoenzyme of creatine kinase (CK-MB) and calcitonin gene related peptide (CGRP) were determined by enzyme linked immunosorbent assay (ELISA); the ultrastructure of myocardium was observed by optical microscopy; the levels of myocardial malondialdehyde (MDA) and superoxide dismutase (SOD) were determined by ELISA, the mRNA expression of myocardial CGRP was assayed by reverse transcription-polymerase chain reaction (RT-PCR), and the protein expression of myocardial CGRP was assayed by Western Blot. Compared with C group, the levels of serum CK-MB and myocardial MDA were significantly increased, serum CGRP content, myocardial SOD activity, and mRNA and protein expressions of myocardial CGRP were significantly decreased in EE group and EP+EE group. Compared with EE group, the levels of serum CK-MB and myocardial MDA in EP+EE group were decreased [CK-MB (U/L): 13.11±0.77 vs. 15.55±0.90, MDA (μmol/L): 389.57±49.60 vs. 709.08±160.49], the level of serum CGRP, and mRNA and protein expressions of myocardium CGRP were increased [serum CGRP (ng/L): 120.41±9.07 vs. 97.97±9.05, CGRP mRNA (2 -ΔΔCT): 0.45±0.09 vs. 0.14±0.02, CGRP protein (gray value): 0.78±0.08 vs. 0.41±0.04, all P < 0.05], the degree of myocardial injury was obviously alleviated. There was no significant difference in the indexes between the EP group and C group. EP has the heart protective effect for the acute EE rats, and the mechanism is closely related to the endogenous protective substance CGRP.

Effects of hydrogen sulfide on inducible nitric oxide synthase activity and expression of cardiomyocytes in diabetic rats.

The aim of the present study was to investigate the effects of hydrogen sulfide (H2S) on the activity and expression of inducible nitric oxide synthase (iNOS) in the myocardial tissue of type 1 diabetic rats. Rats were divided randomly into four groups: Normal control (NC), diabetes mellitus (DM), DM+DL-Proparglygylcine (DM+PAG) and DM+sodium hydrosulfide (DM+NaHS) groups. Type 1 diabetes was induced in the respective groups by a single intraperitoneal (i.p.) injection of streptozotocin. Rats in the DM+PAG and DM+NaHS groups were injected with PAG and NaHS (i.p.) once a day, respectively. The level of fasting blood glucose (FBG), the heart-weight to body-weight (HW/BW) ratio and the ventricular hemodynamic parameters were measured. The activities of serum total NOS (tNOS), iNOS, lactate dehydrogenase (LDH), creatine kinase (CK) and creatine kinase MB isozyme (CK-MB), and the content of nitric oxide (NO) were detected. The contents of myocardial malondialdehyde (MDA) and NO, and the activities of superoxide dismutase (SOD), tNOS and iNOS were determined. The myocardial tissue was examined for histological and ultrastructural alterations. The expression level of iNOS at the transcriptional and translational levels in the myocardial tissue was estimated. The level of FBG was increased in the DM group compared with the NC group, verifying the diabetic condition of the rats. The function of the left ventricle, the myocardial histological alterations and ultrastructures were damaged in the DM group. The DM group additionally demonstrated an increase in the serum NO content and tNOS, iNOS, LDH, CK and CK-MB activities. The myocardial MDA, NO content and tNOS levels were additionally increased in this group. The iNOS activity was increased significantly whereas the myocardial SOD activity was decreased. The increase in the iNOS activity was supported by an enhanced expression level of myocardial iNOS mRNA and protein in the DM group. In the DM+PAG group, in the absence of H2S, the dysfunction of the left ventricle and the oxidative stress injury were increased compared with the DM group. The activity and the expression of tNOS and iNOS were increased significantly. However, the rats in the DM+PAG group demonstrated the opposite effects. In conclusion, H2S exhibits a protective effect on the myocardium in type 1 diabetic rats, which may be associated with the suppression of iNOS activity and expression, a decrease in the NO content and the inhibition of oxidative stress injury.

Effects of Simvastatin on myocardial apoptosis and oxidative stress mechanism in immature rabbits with chronic heart failure

Objective To observe the effects of Simvastatin on myocardial apoptosis and oxidative stress mechanism in immature rabbits with chronic heart failure. Methods Thirty-six male New Zealand big-eared immature rabbits were randomly divided into 3 groups: Adriamycin(ADR)+ Simvastatin group(ADR-s group, n=12), in which ADR(1.5 mg/kg) received injection via the auricular vein of rabbits weekly, and the rabbits received oral Sim-vastatin [1.5 mg/(kg·d)] simultaneously for 12 weeks; ADR group(n=12), in which the rabbits received ADR like ADR-S group, and 9 g/L saline instead of Simvastatin; control group (CON group, n=12), which received the same amount of 9 g/L saline.Echocardiography examination was performed in 13th week.Myocardial fibrosis degree was detected by using MASSON staining, and the myocardial apoptosis was detected by using terminal deoxynucleotidyl transferase dUTP nick end labeling.Colorimetric method was used to detect the myocardial concentration superoxide dismutase (SOD) and malondialdehyde (MDA). Enzyme-linked immunosorbent assay was used to detect serum B-type brain natriuretic peptide (BNP) level. Results (1) In CON group, the immature rabbits were all alive.Four rabbits died in ADR group, and the survival rate was 66.7%, while 2 rabbits died in ADR-s group, and the survival rate was 83.3%.(2)Compared with CON group, the left ventricular end diastolic diameter (LVEDd) and left ventricular end systolic diameter (LVESd) in ADR-s group and ADR group increased [(11.90±1.09) mm, (11.34±0.92) mm vs.(10.73±0.48) mm; (9.80±0.88) mm, (8.47±1.23) mm vs.(7.31±0.36) mm]; left ventricular fractional shortening(LVFS) and left ventricular ejection fraction(LVEF) decreased [(17.65±1.70)%, (22.58±2.19)% vs.(31.79±2.58)%; (41.35±3.19)%, (49.17±3.53)% vs.(64.34±3.97)%], and all the differences were significant(all P<0.05); LVEDd and LVESd in ADR-s group were lower than those of ADR group, while LVEF and LVFS in ADR-s group were higher than those of ADR group, and the differences were significant(all P<0.05). (3) MASSON staining: compared with ADR group, there was less myocardial cell hyperplasia of fibrous tissue in ADR-s group.(4)Compared with CON group, the apoptosis index was higher in ADR and ADR-s group[(34.25±11.13)%, (24.00±6.85)% vs.(16.58±5.34)%], but ADR-s group had less than ADR group, and the diffe-rences were significant (all P<0.05). (5) Compared with ADR group, SOD activity of ADR-s group was higher[(13.40±2.68) kU/L vs.(10.66±2.99) kU/L], but MDA content was lower[(5.67±1.36) μmol/mg vs.(7.08±0.98) μmol/mg], and the differences were significant (all P<0.05). (6) Serum BNP level in ADR group and ADR-s group was higher than that of the CON group[(33.28±9.58) μg/L, (26.71±6.72) μg/L vs.(13.56±2.82) μg/L], while was higher in ADR group than that of ADR-s group, and the differences were significant (all P<0.05). Conclusions Simvastatin can protect cardiac function of immature rabbits with chronic heart failure.The possible mechanism may be the up-regulation of myocardial SOD activity, reduction of cell lipid peroxidation and inhibition of myocardial apoptosis. Key words: Simvastatin; Adriamycin; Chronic heart failure; Myocardial apoptosis; Oxidative stress

The protective effects of Haematococcus pluvialis on the exercise-induced myocardial injury in rat

To study the protective effects of Haematococcus pluvialis (H. pluvialis) on myocardial injury of rats induced by endurance and intensive exercise. The model was based on intensive endurance training. Sixty-five male aged 42 days Wistar rats were randomly divided into 5 groups:control group (C group), general training group (M group), low dose H. pluvialis + training group (HM I group), middle dose H. Pluvialis + training group (HM Ⅱ group), high dose H. pluvialis + training group (HM Ⅲ group). Each group included 12 rats, and the rats were assigned to go on a 42-day swimming training regime. Professional gavage were taken daily. The rats in HM I, HM Ⅱ and HM Ⅲ group were treated with H. pluvialis at the doses of 0.067,0.133 and 0.4 g/kg by ig at 5 ml/kg and the normal saline were given to other groups. After a 42-day swimming training regime, myocardial injury markers such as serum alanine aminotransferase (ALT), myocardial superoxide dismutase(SOD) and malondialdehyde (MDA) were detected, the biochemical indexes such as serum and myocardial endothelin (ET) and calcitonin gene related peptide (CGRP)were detected. Serum ALT, lactate dehydrogenase(LDH), creatine kinase(CK), a-hydroxybutyrate dehydrogenase(a-HBDH), ET, myocardial MDA and ET in M group were significantly higher than those in C group (P<0.05 or P<0.01). The myocardial SOD activity and the myocardial and serum CGRP in M group were significantly lower than those in C group(P<0.05 or P<0.01). The contents of serum ALT, LDH and CK in HM groups were lower than those in the M group but there was no significant difference between the two groups. Compared with M group, H. pluvialis could decrease the levels of serum a-HBDH, ET and myocardial ET in a dose-dependent manner (P<0.05 or P<0.01). The above mentioned three parameters in HM Ⅲ group were lower than those in HM I group (P<0.05). H. pluvialis could decrease the levels of myocardial MDA and increase the levels of myocardial SOD activity and serum or myocardial CGRP in a dose-dependent manner (P<0.05 or P<0.01). The different doses of H.pluvialis can effectively reduce the free radicals caused by endurance and intensive training and enhance the immune function. Meanwhile H.pluvialis is able to guarantee the relative balance in ET an CGRP`s concentration. Therefore, the myocardial lipid peroxidation and myocardial injury are encumbered. Additionaly, high dose of H. pluvialis is proven to be the most effective.

Estrogen receptor α activation enhances its cell surface localization and improves myocardial redox status in ovariectomized rats

AimsLittle is known about the role of subcellular trafficking of estrogen receptor (ER) subtypes in the acute estrogen (E2)-mediated alleviation of oxidative stress. We tested the hypothesis that ERα migration to the cardiac myocyte membrane mediates the acute E2-dependent improvement of cellular redox status. Main methodsMyocardial distribution of subcellular ERα, ERβ and G-protein coupled estrogen receptor (GPER) was determined in proestrus sham-operated (SO) and in ovariectomized (OVX) rats, acutely treated with E2 (1μg/kg) or a selective ERα (PPT), ERβ (DPN) or GPER (G1) agonist (10μg/kg), by immunofluorescence and Western blot. We measured ROS and malondialdehyde (MDA) levels, and catalase and superoxide dismutase (SOD) activities to evaluate myocardial antioxidant/redox status. Key findingsCompared with SO, OVX rats exhibited higher myocardial ROS and MDA levels, reduced catalase and SOD activities, along with diminished ERα, and enhanced ERβ and GPER, localization at cardiomyocyte membrane. Acute E2 or an ERα (PPT), but not ERβ (DPN) or GPER (G1), agonist reversed these responses in OVX rats and resulted in higher ERα/ERβ and ERα/GPER ratios at the cardiomyocytes membrane. PPT or DPN enhanced myocardial Akt phosphorylation. We present the first evidence that preferential aggregation of ERα at the cardiomyocytes plasma membrane is ERα-dependent, and underlies E2-mediated reduction in oxidative stress, at least partly, via the enhancements of myocardial catalase and SOD activities in OVX rats. SignificanceThe findings highlight ERα agonists as potential therapeutics for restoring the myocardial redox status following E2 depletion in postmenopausal women.

Transduction of PEP-1–Heme Oxygenase-1 Fusion Protein Reduces Myocardial Ischemia/Reperfusion Injury in Rats

Recent studies have uncovered that overexpression of heme oxygenase-1 (HO-1) by induction or gene transfer provides myocardial protection. In the present study, we investigated whether HO-1 protein mediated by cell-penetrating peptide PEP-1 could confer cardioprotection in a rat model of myocardial ischemia/reperfusion (I/R) injury. Male Sprague-Dawley rats were subjected to 30 minutes of ischemia by occluding the left anterior descending coronary artery and to 120 minutes of reperfusion to prepare the model of I/R. Animals were randomized to receive PEP-1-HO-1 fusion protein or saline 30 minutes before a 30-minute occlusion. I/R increased myocardial infarct size and levels of malondialdehyde, serum tumor necrosis factor alpha, and interleukin 6 and reduced myocardial superoxide dismutase activity. Administration of PEP-1-HO-1 reduced myocardial infarct size and levels of malondialdehyde, serum tumor necrosis factor alpha, and interleukin 6 and increased myocardial superoxide dismutase and HO-1 activities. His-probe protein was only detected in PEP-1-HO-1-transduced hearts. In addition, transduction of PEP-1-HO-1 markedly reduced elevated myocardial tissue nuclear factor-κB induced by I/R. The results suggested that transduction of PEP-1-HO-1 fusion protein decreased myocardial reperfusion injury, probably by attenuating the production of oxidants and proinflammatory cytokines regulated by nuclear factor-κB.

Myocardial protective effects of micro-flow perfusion with blood Plegisol solution

Objective To study the myocardial protective effect of micro-flow perfusion with blood Plegisol solution on warm ischemic pig heart and the mechanism.Methods Twelve isolated pig hearts were subjected to orthotopic heart transplantation and randomly divided into experimental group (n =6,warm ischemia for 10 min,4℃ blood the micro-flow continuous infusion for 8 h,and warm-blooded continuous perfusion during transplantation) and control group (n =6,wark ischemia for 10 min,and immersion with 4℃ Plegisol liquid alone for 8 h).The pathological changes of myocardial tissue in all pig hearts after reperfusion were observed.The superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in myocardial tissue were measured by xanthine oxidase and thiobarbituric acid method.Immunohistochemistry was used to detect B lymphocytes/leukemia-2 (bcl-2) and Caspase-3 protein expression.Results In control group,coronary endothelial and myocardial tissue injury was more serious than in experimental group.As compared with control group,myocardial tissue SOD activity [(7.88 ± 0.41) U/(mg· protein)] was significantly increased,and MDA content [(9.97 ± 1.05) nmol/(mg· protein)] was significantly reduced in experimental group (P ＜ 0.05).The expression levels of bcl-2 mRNA and protein in experimental group (0.651 ±0.052 and 0.506 ±0.048) were significantly increased as compared with control group (0.337 ±0.026 and 0.271 ±0.022),and those of Caspase-3 mRNA and protein in experimental group (0.343 ± 0.027 and 0.215 ± 0.019) were significantly decreased as compared with control group [(0.782 ±0.059 and 0.629 ±0.054),P ＜0.01].Conclusion The mechanism by which micro-flow perfusion with blood Plegisol solution protects warm ischemic pig heart may be related to the alleviation of the isolated pig heart coronary endothelial and myocardial edema,reduction of the reperfusion oxidative damage and the inhibition of cardiac apoptosis. Key words: Micro-flow infusion; Warm ischemic; Myocardial protective

Effect of low level laser irradiation on superoxide dismutase activity and malondialdehyde content in infarcted myocardial tissue of rats

Objective To investigate effect of low level laser irradiation (LLLI) on superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in infarcted myocardial tissue of rats.Methods Myocardial infarction (MI) was created by the left anterior descending (LAD) coronary artery ligation in 90 rats.The surviving rats were divided randomly into sham operated,control and laser groups.Thirty rats received a thoracotomy without coronary ligation as sham operated group.Three weeks after MI,all the rats received a thoracotomy.The rats in laser group were exposed to a diode laser (635 nm,6 mW,150 s,0.96 J/cm2).In the control and sham operated groups,laser irradiation was not applied.At different time points after second thoracotomy,4-6 rats from each group were sacrificed and the infarcted myocardial tissues were analyzed to determine SOD activity and MDA content at each time point.The MI was determined from histological sections stained with hematoxylin and eosin (HE).Results From 1 h to 48 h after LLLI,the myocardial SOD activity was higher in laser group than in control group,and reached the peak at 48 h [(0.94 ± 0.47) U/mg protein vs (0.92 ± 0.25) U/mg protein,P ＜ 0.05],and myocardial MDA content was decreased in laser group as compared with control group and touched the bottom at 48 h [(0.48 ±0.20) nmol/mg protein vs.(0.52 ±0.25) nmol/mg protein,P ＜0.05].There was no statistically significant difference in the SOD activity and MDA content between laser group and control group at 72 h and 1 week after LLLI.Conclusion LLLI increases SOD activity and decreases MDA content in infarcted myocardial tissue after MI,and has a better cardioprotective effect. Key words: Low level laser irradiation; Myocardial infarction; Superoxide dismutase; Malondialdehyde

Effect of levothyroxine and vitamin E treatment on oxidative stress and myocardial apoptosis in rats with hypothyroidism

Objective To investigate the oxidative stress status and cardiac myocyte apoptosis in rats with propylthiouracil-induced hypothyroidism and to examine the effect of levothyroxine ( LT4 ),vitamin E ( VitE ),and both supplementation on this experimental model.Methods Male Sprague Dawley rats were divided into normal control group( NC),propylthiouracil group( PTU ),LT4 treatment group( PTU + LT4 ),VitE treatment group ( PTU +VitE),LT4 and VitE combination therapy group (PTU + LT4 + VitE).Serum T3,T4,TSH levels,serum and myocardial superoxide dismutase ( SOD ) activity and malondialdehyde ( MDA ) content were determined.Cardiac myocyte apoptotic index was made with TUNEL.Results ( 1 ) Compared with NC group,T3 and T4 levels were significantly lower and TSH level was significantly higher in PTU group and PTU+VitE groups( P＜0.05 ).Compared with PTU group,T3 and T4 levels were significantly higher and TSH level was significantly lower in PTU + LT4 group and PTU + LT4 + VitE group( P＜0.05 ).There were no statistical differences in T3,T4,and TSH levels between PTU group and PTU + VitE group( P＞0.05 ).( 2 ) Compared to NC group,serum and myocardial MDA levels in PTU group increased significantly( P＜0.05 ),serum SOD activity decreased significantly ( P＜0.05 ),while myocardial SOD activity showed no significant difference( P＞0.05 ).( 3 ) Compared with NC group,myocardial apoptosis index was significantly higher in PTU and PTU + VitE groups( P＜0.05 ).Compared with PTU group,myocardial apoptosis index was significantly lower in PTU + LT4 group and PTU + LT4 + VitE group( P＜0.05 ).Conclusion LT4,VitE,and their combined treatment of hypothyroidism in rats reduce the myocardial cells apoptosis,which may be related to the improvement of thyroid function and amelioration of oxidative stress. Key words: Hypothyroidism; Levothyroxine; Vitamin E; Oxidative stress; Myocardial apoptosis index

Effect of glutathione on canine myocardial ischaemia without reperfusion.

The present study was to evaluate the effect of exogenous glutathione on myocardial damage resulting from permanent (no reperfusion) coronary ligation (3 or 6 h) in anaesthetized dogs. Haemodynamics, infarct size and myocardial glutathione content were determined. Erythrocyte superoxide dismutase (SOD) activity was also determined in coronary venous blood samples. Glutathione was administered by the intraperitoneal route, 100 mg kg-1 as initial dose given 5 min before coronary ligation, and successive doses of 25 mg kg-1 every 40 min throughout the study period. Saline-treated dogs showed myocardial infarction, a decrease in myocardial glutathione content, and a transient increase in SOD activity. Three hours occlusion in glutathione-treated dogs resulted in a small reduction of infarct size, and no changes in myocardial glutathione content and SOD activity. By contrast, administration of glutathione failed to reduce infarct size and failed to prevent myocardial glutathione decrease in dogs subjected to 6 h occlusion. These results indicate that exogenous glutathione is of minor beneficial effect for myocardial damage resulting from permanent coronary occlusion and suggest that endogenous glutathione has a limited role in protecting against myocardial ischaemia without reperfusion.

Amelioration of doxorubicin-induced cardiotoxicity by deferiprone in rats

The therapeutic usefulness of doxorubicin (Dox), an anthracycline antibiotic used as an anticancer agent, is limited by its cardiotoxicity. Dox-induced cardiotoxicity is mainly attributed to accumulation of reactive oxygen species and interaction of Dox with cellular iron metabolism. The present study investigated the effects of the iron chelator deferiprone (Def) against Dox-induced cardiotoxicity in rats. Dox (15mg/kg) was injected intraperitoneally as a single dose, and Def (10mg/kg) was administered orally for 10days. Dox showed cardiotoxicity as evidenced by increased heart rate, elevated ST segment, prolonged QTc interval, and increased T wave amplitude. In addition, Dox enhanced aconitine cardiotoxicity by decreasing its dose, producing ventricular tachycardia. Administration of Def significantly attenuated Dox-induced electrocardiographic changes. Cardiotoxicity of Dox was confirmed biochemically by a significant elevation in serum creatine kinase-MB and lactate dehydrogenase activities as well as by myocardial malondialdehyde and reduced glutathione contents. Moreover, Dox caused a significant decrease in myocardial superoxide dismutase activity. Administration of Def significantly attenuated the biochemical changes. These results suggest that Def might be a potential cardioprotective agent against Dox-induced cardiotoxicity.

Dietary palm olein oil augments cardiac antioxidant enzymes and protects against isoproterenol-induced myocardial necrosis in rats

Wistar rats, 150-200 g, of either sex, were fed daily with commercial rat diet supplemented with palm olein oil in two doses (5% v/w (n = 16) and 10% v/w (n = 16) of diet) for 30 days. Control rats (n = 16) were fed with normal diet. On the 29(th) and 30(th) days, 8 rats from each group were administred isoproterenol (85 mg/kg, s.c., 24-h interval). On the 31(st) day, all rats were sacrificed and myocardial tissues were studied for thiobarbituric acid reactive substances (TBARS), antioxidant enzymes and light microscopic changes, along with the ferric-reducing ability of plasma (FRAP). A significant rise in myocardial superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) activity and FRAP level were observed in rats fed with palm olein oil. Isoproterenol caused an increase in myocardial oxidative stress in control rats, as evidenced by an increase in myocardial TBARS level, reduction in FRAP and myocardial SOD, catalase and GPx activity, along with focal necrosis of cardiac muscle fibres on light microscopy. The rise in myocardial TBARS and depletion of SOD and catalase activity following isoproterenol administration were prevented in palm-olein-oil-supplemented diet-fed rats at both doses. Isoproterenol-induced myocardial light-microscopic changes were also prevented in the treated groups. The results suggest that dietary palm olein oil caused augmentation of myocardial antioxidant enzymes and protected against isoproterenol-induced myocardial necrosis and associated oxidative stress.

Chronic oral administration of Ocimum sanctum Linn. augments cardiac endogenous antioxidants and prevents isoproterenol-induced myocardial necrosis in rats

Wistar rats (200-250 g) of either sex were fed with fresh leaf homogenate of Ocimum sanctum by oral gavage in two different doses, 50 mg kg-1(Os 50) and 100 mg kg-1 (Os 100), daily for 30 days. This was followed by isoproterenol administration (85 mg kg-1 s.c. two doses at 24h intervals) in both control and 0. sanctum-fed rats to induce myocardial necrosis. Hearts were isolated for estimation of endogenous myocardial antioxidants (superoxide dismutase (SOD), catalase, reduced glutathione (GSH) and glutathione peroxidase (GPx) and myocardial lipid peroxidation) and light microscopic study. Increased basal myocardial antioxidant SOD (9.3 +/- 1.2 vs 3.7 +/- 0.7 units mg-1 protein; P<0.05) and catalase activities (34.3 +/- 5.4 vs 17.9 +/- 5.1 units mg-1 protein; P< 0.05) were observed in the Os 50 group only without any evidence of cellular injury in both the groups. In control rats, isoproterenol administration caused significant depletion of myocardial SOD (1.7 +/- 0.2 units mg-1 protein) and GPx (104 +/- 2mU mg-1 protein) activities and increase in GSH (551.7 +/- 30.9, microg g-1 wet weight of tissue) level, with evidence of myocardial necrosis. Isoproterenol-induced changes in myocardial SOD, GPx and GSH were prevented by both the doses of 0. sanctum, however cellular injury was minimal only with 50mg kg-1. The results indicate that long-term feeding of 0. sanctum offered significant protection against isoproterenol-induced myocardial necrosis through a unique property of enhancement of endogenous antioxidants.

The effect of L-tryptophan on the heart in rabbits via chronic hypoxia

To evaluate the protective effect of tryptophan on an experimentally produced hypoxic myocardial injury via biochemical and pathological parameters. Materials and methods: A total of 26 rabbits were divided into 3 groups. Group 1 (n = 9) was only exposed to hypoxia. Group 2 (n = 10) was exposed to hypoxia and received L-tryptophan (200 mg/kg per day, orally for 5 days). Group 3 (n = 7) was the control group. Before the hypoxic injury and after the delivery of the medication, serum samples were taken for troponin-I, creatine kinase myocardial isoenzymes (CK-MB), lactate dehydrogenase (LDH), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), malondialdehyde (MDA), and nitric oxide (NO) analysis, and then the rabbits were sacrificed. Next, the myocardium samples were taken and the myocardial NO, MDA, SOD, and GSH-Px enzyme activity levels were studied histopathologically. Results: In group 1, Serum GSH-Px and SOD activities were decreased. Conversely, troponin-I, CK-MB, and LDH were elevated. Severe cardiac injury was observed histopathologically. In group 2, serum troponin-I and SOD values were increased. Mild cardiac injury was demonstrated histopathologically. When groups 1 and 2 were compared, tissue NO and MDA levels in group 1 were higher compared to group 2, but GSH-Px level was found decreased in group 1. Conclusion: Our findings support that there is a clear effect of the free oxygen radicals and the lipid peroxidation products on hypoxic cardiac injury. In addition, L-tryptophan supplementation has a strong protective effect on hypoxic heart by antioxidant activity.

Extracellular Superoxide Dismutase Deficiency Exacerbates Pressure Overload–Induced Left Ventricular Hypertrophy and Dysfunction

Extracellular superoxide dismutase (SOD) contributes only a small fraction to total SOD activity in the normal heart but is strategically located to scavenge free radicals in the extracellular compartment. To examine the physiological significance of extracellular SOD in the response of the heart to hemodynamic stress, we studied the effect of extracellular SOD deficiency on transverse aortic constriction (TAC)-induced left ventricular remodeling. Under unstressed conditions extracellular SOD deficiency had no effect on myocardial total SOD activity, the ratio of glutathione:glutathione disulfide, nitrotyrosine content, or superoxide anion production but resulted in small but significant increases in myocardial fibrosis and ventricular mass. In response to TAC for 6 weeks, extracellular SOD-deficient mice developed more severe left ventricular hypertrophy (heart weight increased 2.56-fold in extracellular SOD-deficient mice as compared with 1.99-fold in wild-type mice) and pulmonary congestion (lung weight increased 2.92-fold in extracellular SOD-deficient mice as compared with 1.84-fold in wild-type mice). Extracellular SOD-deficient mice also had more ventricular fibrosis, dilation, and a greater reduction of left ventricular fractional shortening and rate of pressure development after TAC. TAC resulted in greater increases of ventricular collagen I, collagen III, matrix metalloproteinase-2, matrix metalloproteinase-9, nitrotyrosine, and superoxide anion production. TAC also resulted in a greater decrease of the ratio of glutathione:glutathione disulfide in extracellular SOD-deficient mice. The finding that extracellular SOD deficiency had minimal impact on myocardial overall SOD activity but exacerbated TAC induced myocardial oxidative stress, hypertrophy, fibrosis, and dysfunction indicates that the distribution of extracellular SOD in the extracellular space is critically important in protecting the heart against pressure overload.

Effect of GCP-02, a PPARalpha/gamma dual activator, on glucose and lipid metabolism in insulin-resistant mice

This paper reports on the effect of GCP-02, a dual activator of the peroxisome proliferator-activated receptors alpha/gamma (PPARalpha/gamma), on glucose and lipid metabolism in insulin-resistant obese mice induced by monosodium glutamate. The mice were divided into four groups on the basis of treatment: control group, rosiglitazone (positive control) (7 μmol/kg), and low- and high-dosage GCP-02 (7 μmol/kg and 3.5 μmol/kg, respectively). Drugs were given orally once a day for 19 days, and mice underwent testing for insulin tolerance, oral glucose tolerance and gluconeogenesis, and plasma cholesterol, triglyceride and free fatty acid levels. Mice were sacrificed, and body length and weight were measured; intraperitoneal adipose, heart and liver weighed; and plasma alanine aminotransferase (ALT) level and aspartate aminotransferase (AST) activity measured. Liver, soleus muscle and myocardium were assayed for glycogen, triglyceride and free fatty acid content and myocardia tested for superoxide dismutase (SOD) activity and malonaldehyde content. RT-PCR revealed expression of insulin receptor substrate 1 and 2 (IRS1, IRS2) and related genes in liver. GCP-02 had a more powerful effect than rosiglitazone on improving insulin sensitivity, ameliorating glucose tolerance, suppressing l-alanine-induced gluconeogenesis, and decreasing plasma levels of cholesterol, triglyceride and free fatty acid. It reduced body weight in control mice, significantly lowered hepatic content of glycogen, triglyceride and free fatty acid and myocardial content of triglyceride, and increased myocardial SOD activity. IRS2 mRNA was down-regulated in control mice but up-regulated by GCP-02. Thus, GCP-02 is a potential candidate for the prevention and therapy of diseases associated with insulin resistance such as type 2 diabetes mellitus and cardiovascular disease.

Effect of Ocimum sanctum Linn. on cardiac changes in rats subjected to chronic restraint stress

Male Wistar rats were subjected to chronic restraint stress (CRS; 6 h/day for 21 days) alone or along with either hydroalcoholic extract of Ocimum sanctum (Os; 100 mg/kg; orally) or MK-801, an NMDA receptor antagonist (0.3 mg/kg; i.p.). In the rats subjected to only CRS, plasma cAMP level was significantly raised on day 21, with no significant change in plasma corticosterone level. There was a significant ( p < 0.05) fall in myocardial glutathione level, along with a significant ( p < 0.05) rise in myocardial superoxide dismutase (SOD) and catalase activities, while light microscopy showed evidence of myocardial edema. Both Os and MK-801 significantly prevented the CRS-induced rise in plasma cAMP level, myocardial SOD and catalase activities as well as the light microscopic changes in the myocardium. This study revealed that Ocimum sanctum protects rat heart from chronic restraint stress induced changes, through its central effect.