Effects of carvedilol on cardiomyocyte apoptosis and gene expression in vivo after ischemia-reperfusion in rats

Ghrelin prevents cardiac cell apoptosis during cardiac remodelling post experimentally induced myocardial infarction in rats via activation of Raf-MEK1/2-ERK1/2 signalling

CONTEXT

Mechanisms by which ghrelin affords its cardioprotection in mammals remained unclear.

OBJECTIVE

To examine if ghrelin confers cardio-protection during cardiac remodelling post-MI by modulating the RAF-1-MEK1/2-ERK1/2 signalling pathway.

MATERIALS AND METHODS

Rats were divided into control, sham, sham + ghrelin, myocardial infarction (MI), and MI + ghrelin groups. Ghrelin (100 µg/kg) was administered for 21 days, starting one-day post-MI.

RESULTS

Ghrelin enhanced cardiac contractility and the activities of antioxidant enzymes, lowered serum levels of enzyme markers of cardiac dysfunction, and lowered inflammatory mediator levels. Ghrelin increased levels of phospho-Raf-1 (Ser³³⁸), phospho-MEK1/2 (Ser^217/221), phospho-ERK1/2 (Thr²⁰²/Tyr²⁰⁴), and of their downstream target p-BAD (Ser¹¹²) and inhibited the cleavage of caspase-3. Concomitantly, ghrelin prevented the increases in the levels of fibrotic markers, including α-smooth muscle actin (α-SMA), metalloproteinase-9 (MPP-9), and type III collagen.

CONCLUSION

Post-MI in rats, ghrelin stimulated Raf-1-MEK1/2-ERK1/2-BAD signalling in the LV infarct areas, accounting for its anti-apoptotic effect, enhancing cardiac function, and inhibiting cardiac fibrosis during cardiac remodelling.

Carvedilol and antioxidant proteins in a type I diabetes animal model

BACKGROUND

Patients with diabetes are at a high risk of developing both micro- and macrovascular disease. Hyperglycaemia seems to be the main factor in the pathogenesis of diabetic cardiomyopathy, often based on increased oxidative stress. Carvedilol, a β-adrenergic blocker, has intrinsic antioxidant properties and was previously described to be effective in the protection of cardiac mitochondria against oxidative stress. The objective of this study was to evaluate the effect of carvedilol on hyperglycaemia-induced oxidative damage and mitochondrial abnormalities in cardiac and skeletal muscle in streptozotocin-treated rats.

MATERIALS AND METHODS

Body mass, blood glucose, the level of protein carbonylation, caspase-9- and caspase-3-like activities, mitochondrial proteins, the status of antioxidant defence system and stress-related proteins were evaluated in streptozotocin vs streptozotocin + carvedilol (1 mg/kg/day)-treated rats.

RESULTS

The results showed that carvedilol decreased blood glucose in streptozotocin-treated animals. Content of catalase in the heart and SOD2, SOD1 and catalase in skeletal muscle were increased by carvedilol treatment in streptozotocin-treated animals. At this particular time point, streptozotocin-induced hyperglycaemia did not cause caspase activation or increase in protein carbonylation status. The data showed that carvedilol increased the level of antioxidant enzymes, what may contribute to preserve cell redox balance during hyperglycaemia. We also showed here for the first time that carvedilol effects on streptozotocin-treated rats are tissue dependent, with a more predominant effect on skeletal muscle.

CONCLUSIONS

Based on data showing modulation of the antioxidant network in the heart, carvedilol may be beneficial in diabetic patients without advanced disease complications, delaying their progression.

Effects of carvedilol on an ischemia/reperfusion model: Biochemical, histopathological and immunohistochemical evaluation

AIM

The aim of this study was to investigate the effects of carvedilol (CVD) on experimentally induced ovarian ischemia/reperfusion (I/R) injury in rats.

METHODS

An ovarian I/R model was applied to rats, classified into three groups: 1 (n = 7), sham operated (control); 2 (n = 7), 3 h ischemia + 3 h reperfusion (I/R); 3 (n = 7), 3 h ischemia + CVD + 3 h reperfusion (I/R + CVD). Malondialdehyde (MDA) levels and glutathione peroxidase (GSH-Px) and superoxide dismutase (SOD) activities in ovarian tissues and serum were measured. Tissue damage was examined histopathologically; Bax and caspase-3 expression was determined immunhistochemically. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed to show apoptotic cell death.

RESULTS

MDA levels in ovarian tissues were significantly increased in the I/R group compared with the control. CVD administration significantly decreased tissue MDA levels in the I/R + CVD in comparison with the I/R group. GSH-Px activities in serum were higher in the I/R + CVD than in the I/R group. SOD activities in tissue and serum were significantly decreased in the I/R compared with the control group. Histological examination showed a significant improvement in ovarian morphology in the I/R + CVD compared with the I/R group. Bax and caspase-3 protein was more strongly expressed in the I/R group compared with the control and I/R + CVD groups. Apoptotic index detected by TUNEL assay was significantly increased in the I/R and decreased in the I/R + CVD group.

CONCLUSION

Our results suggest that CVD reduces the deleterious effects of oxidative damage on ovaries in a rat I/R model.

Carvedilol enhances mesenchymal stem cell therapy for myocardial infarction via inhibition of caspase-3 expression

Adult stem cells have shown great promise toward repairing infarcted heart and restoring cardiac function. Mesenchymal stem cells (MSCs), because of their inherent multipotent nature and their ability to secrete a multitude of growth factors and cytokines, have been used for cardiac repair with encouraging results. Preclinical studies showed that MSCs injected into infarcted hearts improve cardiac function and attenuate fibrosis. Although stem cell transplantation is a promising therapeutic option to repair the infarcted heart, it is faced with a number of challenges, including the survival of the transplanted cells in the ischemic region, due to excessive oxidative stress present in the ischemic region. The objective of this study was to determine the effect of Carvedilol (Carv), a nonselective β-blocker with antioxidant properties, on the survival and engraftment of MSCs in the infarcted heart. MSCs were subjected to a simulated host-tissue environment, similar to the one present in the infarcted myocardium, by culturing them in the presence of hydrogen peroxide (H(2)O(2)) to induce oxidative stress. MSCs were treated with 2.5 μM Carv for 1 h in serum-free medium, followed by treatment with H(2)O(2) for 2 h. The treated cells exhibited significant protection against H(2)O(2)-induced cell death versus untreated controls as determined by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays. Likewise, transplantation of MSCs after permanent left coronary artery ligation and treatment of animals after myocardial infarction (MI) with Carv (5 mg/kg b.wt.) led to significant improvement in cardiac function, decreased fibrosis, and caspase-3 expression compared with the MI or MSC-alone groups.

Effect of oxidative stress on ventricular arrhythmia in rabbits with adriamycin-induced cardiomyopathy

The purpose of the present study was to examine the effects of oxidative stress on ventricular arrhythmias in rabbits with adriamycin-induced cardiomyopathy and the relationship between oxidative stress and ventricular arrhythmia. Forty Japanese white rabbits were randomly divided into four groups (n=10 in each): control group, metoprolol (a selective β1 receptor blocker) group, carvedilol (a nonselective β blocker/α-1 blocker) group and adriamycin group. Models of adriamycin-induced cardiomyopathy were established by intravenously injecting adriamycin hydrochloride (1 mg/kg) to rabbits via the auri-edge vein twice a week for 8 weeks in the adriamycin, metoprolol and carvedilol groups. Rabbits in the control group were given equal volume of saline through the auri-edge vein. Rabbits in the metoprolol and carvedilol groups were then intragastrically administrated metoprolol (5 mg/kg/d) and carvedilol (5 mg/kg/d) respectively for 2 months, while those in the adriamycin and control groups were treated with equal volume of saline in the same manner as in the metroprolol and carvedilol groups. Left ventricular end diastolic diameter (LVEDd) and left ventricular ejection fraction (LVEF) were measured by echocardiography. Plasma levels of N-terminal pro B-type natriuretic peptide (NT-proBNP), malondialdehyde (MAD) and superoxide dismutase (SOD) were detected. The left ventricular wedge preparations were perfused with Tyrode's solution. The transmural electrocardiogram, transmural action potentials from epicardium (Epi) and endocardium (Endo), transmural repolarization dispersion (TDR) were recorded, and the incidences of triggered activity and ventricular arrhythmias were obtained at rapid cycle lengths. The results showed that TDR and the serum MDA and NT-proBNP levels were increased, and LVEF and the serum SOD level decreased in the adriamycin group compared with the control group. The incidences of triggered activity and ventricular arrhythmia were significantly higher in the adriamycin group than those in the control group (P<0.05). In the carvedilol group as compared with the adriamycin group, the serum SOD level and the LVEF were substantially increased; the TDR, and the serum MDA and NT-proBNP levels were significantly decreased; the incidences of triggered activity and ventricular arrhythmia were obviously reduced (P<0.05). There were no significant differences in the levels of MDA and SOD, LVEF, TDR and the incidences of triggered activity and ventricular arrhythmia between the adriamycin group and the metoprolol group. It was concluded that carvedilol may inhibit triggered activity and ventricular arrhythmias in rabbit with adriamycin-induced cardiomyopathy, which is related to the decrease in oxygen free radials.

Hypothermia protects H9c2 cardiomyocytes from H2O2 induced apoptosis

The purpose of our study was to investigate underlying basic mechanisms of hypothermia-induced cardioprotection during oxidative stress in a cardiomyocyte cell culture model. For hypothermic treatment we cooled H9c2 cardiomyocytes to 20°C, maintained 20min at 20°C during which short-term oxidative damage was inflicted with 2mM H(2)O(2,) followed by rewarming to 37°C. Later on, we analyzed lactate dehydrogenase (LDH), caspase-3 cleavage, reactive oxygen species (ROS), mitochondrial activity, intracellular ATP production, cytoprotective signal molecules as well as DNA damage. Hypothermia decreased H(2)O(2) damage in cardiomyocytes as demonstrated in a lower LDH release, less caspase-3 cleavage and less M30 CytoDeath staining. After rewarming H(2)O(2) damaged cells demonstrated a significantly higher reduction rate of intracellular ROS compared to normothermic H(2)O(2) damaged cardiomyocytes(.) This was in line with a significantly greater mitochondrial dehydrogenase activity and higher intracellular ATP content in cooled and rewarmed cells. Moreover, hypothermia preserved cell viability by up-regulation of the anti-apoptotic protein Bcl-2 and a reduction of p53 phosphorylation. DNA damage, proven by PARP-1 cleavage and H2AX phosphorylation, was significantly reduced by hypothermia. In conclusion, we could demonstrate that hypothermia protects cardiomyocytes during oxidative stress by preventing apoptosis via inhibiting mitochondrial dysfunction and DNA damage.

Cardiac oxidative stress and remodeling following infarction: role of NADPH oxidase

BACKGROUND

There is growing recognition that oxidative stress plays a role in the pathogeneses of myocardial repair/remodeling following myocardial infarction (MI). Nicotinamide adenine denucleotide phosphate (NADPH) oxidase is a major source for cardiac reactive oxygen species production. Herein, we studied the importance of NADPH oxidase in development of cardiac oxidative stress and its induced molecular and cellular changes related to myocardial repair/remodeling.

METHODS

MI was created by coronary artery ligation in C57/BL (wild type) and NADPH oxidase (gp91(phox)) knockout mice. Cardiac oxidative stress, inflammatory/fibrogenic responses, apoptosis, and hypertrophy were detected by in situ hybridization, immunohistochemistry, terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL), picrosirius red staining, and image analysis, respectively, at different stages post MI.

RESULTS

In wild-type mice with MI, and compared to sham-operated animals, we observed significantly increased gp91(phox) and 3-nitrotyrosine, a marker of oxidative stress, in the infarcted myocardium; accumulated macrophages and myofibroblasts at the infarct site; abundant apoptotic myocytes primarily at border zones on Day 3; and numerous apoptotic inflammatory/myofibroblasts in the later stages. In addition, we detected significantly increased transforming growth factor beta1, tissue inhibitor of metalloprotease 2, and type 1 collagen gene expression; continuously increasing collagen volume in the infarcted myocardium; and hypertrophy in noninfarcted myocardium. Compared to wild-type mice with MI, we did not observe significant difference in infarct size/thickness, cardiac hypertrophy, myocyte apoptosis, inflammatory/fibrogenic responses, as well as cardiac oxidative stress in gp91(phox) knockout mice.

CONCLUSION

Our findings indicate that during NADPH oxidase deficiency, superoxide production can be compensated by other sources, which leads to cardiac oxidative stress and its related molecular/cellular events in the infarcted heart.

Oxidative Stress and Cardiac Repair/Remodeling Following Infarction

Extensive cardiac remodeling after myocardial infarction (MI) contributes significantly to ventricular dysfunction. Factors regulating left ventricular remodeling at different stages after MI are under investigation. There is growing recognition and experimental evidence that oxidative stress mediated by reactive oxygen species plays a role in the pathogeneses of myocardial repair/remodeling in various cardiac diseases. After acute MI, oxidative stress is developed in both infarcted and noninfarcted myocardium. Accumulating evidence has demonstrated that oxidative stress participates in several aspects of cardiac repair/remodeling after infarction that include cardiomyocyte apoptosis, inflammatory/fibrogenic responses, and hypertrophy. The exact pathways on reactive oxygen species-mediated myocardial remodeling are under investigation. The therapeutic potential of oxidative stress-directed drugs in myocardial remodeling after infarction has not been fully realized.

Carvedilol improved diabetic rat cardiac function depending on antioxidant ability

The risk for cardiovascular disease is significantly high in diabetes mellitus. Oxidative stress plays a dominant role in the pathogenesis of diabetes mellitus. Bcl-2 gene has a close connection with antagonizing oxidative stress destroy in many diseases including diabetes. Carvedilol, an adrenoceptor blocker, also has antioxidant and free radical scavenger properties. To study the effect of carvedilol on the antioxidant status and expression of Bcl-2 in healthy and diabetic hearts, we investigated carvedilol-administrated healthy and streptozotocin-induced diabetic rats. After small and large dosage (1 or 10mg/kg/d) carvedilol-administrated for 5 weeks, hemodynamic parameters, the levels of malondialdehyde (MDA), the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and expression of Bcl-2 mRNA in the cardiac tissues of all six groups were measured. Diabetic rats had higher left ventricular end diastolic pressure (LVEDP), lower maximal rate of rise/fall left ventricle pressure development and decline (+/-dP/dtmax). These parameters were improved by administration of carvedilol. Diabetic rats showed elevated MDA level and CAT activity, but lower activities of SOD and GSH-Px. Carvedilol treatment increased activities of antioxidant enzymes and expression of Bcl-2 in healthy rats as well as diabetic rats. These results indicate that carvedilol improves cardiac function via its antioxidant property in diabetic rats partly.

Carvedilol protected diabetic rat hearts via reducing oxidative stress

Oxidative stress plays a dominant role in the pathogenesis of diabetes mellitus. Bcl-2 gene has close connection with antioxidant stress destruction in many diseases including diabetes. Carvedilol, an adrenoceptor blocker, also has antioxidant properties. To study the effect of carvedilol on the antioxidant status in diabetic hearts, we investigated carvedilol-administrated healthy and streptozotocin-induced diabetic rats. After small and large dosage carvedilol-administered for 5 weeks, hemodynamic parameters, the levels of malondialdehyde, activities of antioxidant enzymes and expression of Bcl-2 mRNA in the cardiac tissues were measured. The diabetic rats not only had cardiac disfunction, weaker activities of antioxidant enzymes, but also showed lower expression of Bcl-2. Carvedilol treatment increased activities of antioxidant enzymes and expression of Bcl-2 in healthy rats as well as diabetic rats. These results indicated that carvedilol partly improves cardiac function via its antioxidant properties in diabetic rats.