cytochrome-c-t and Diabetic-Cardiomyopathies

Metabolic disorders often lead to cardiac complications. Metabolic deregulations during diabetic conditions are linked to mitochondrial dysfunctions, which are the key contributing factors in cardiac hypertrophy. However, the underlying mechanisms involved in diabetes-induced cardiac hypertrophy are poorly understood. In the current study, we initially established a diabetic rat model by alloxan-administration, which was validated by peripheral glucose measurement. Diabetic rats displayed myocardial stiffness and fibrosis, changes in heart weight/body weight, heart weight/tibia length ratios, and enhanced size of myocytes, which altogether demonstrated the establishment of diabetic cardiac hypertrophy (DCH). Furthermore, we examined the expression of genes associated with mitochondrial signaling impairment. Our data show that the expression of PGC-1α, cytochrome c, MFN-2, and Drp-1 was deregulated. Mitochondrial-signaling impairment was further validated by redox-system dysregulation, which showed a significant increase in ROS and thiobarbituric acid reactive substances, both in serum and heart tissue, whereas the superoxide dismutase, catalase, and glutathione levels were decreased. Additionally, the expression levels of pro-apoptotic gene PUMA and stress marker GATA-4 genes were elevated, whereas ARC, PPARα, and Bcl-2 expression levels were decreased in the heart tissues of diabetic rats. Importantly, these alloxan-induced impairments were rescued by N-acetyl cysteine, ascorbic acid, and selenium treatment. This was demonstrated by the amelioration of myocardial stiffness, fibrosis, mitochondrial gene expression, lipid profile, restoration of myocyte size, reduced oxidative stress, and the activation of enzymes associated with antioxidant activities. Altogether, these data indicate that the improvement of mitochondrial dysfunction by protective agents such as N-acetyl cysteine, selenium, and ascorbic acid could rescue diabetes-associated cardiac complications, including DCH.

Topics: Acetylcysteine; Animals; Antioxidants; Apoptosis; Apoptosis Regulatory Proteins; Ascorbic Acid; Biomarkers; Blood Glucose; Body Weight; Calcium; Cardiomegaly; Cardiotonic Agents; Cytochromes c; Diabetic Cardiomyopathies; Disease Models, Animal; Down-Regulation; GATA4 Transcription Factor; Lipid Peroxidation; Lipids; Mitochondria, Heart; Myocardium; Oxidation-Reduction; Oxidative Stress; Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; PPAR alpha; Rats, Sprague-Dawley; Reactive Oxygen Species; RNA, Messenger; Selenium

Mitochondrial dysfunction is essential in the development and prognosis of diabetic cardiomyopathy (DCM). Resveratrol (RES) is thought as a mitochondrial protector. In this study, we hypothesized that RES may ameliorate mitochondrial function and consequently improve cardiac function in diabetic rats, and uncoupling protein 2 (UCP2) was involved in the protective effects of RES on DCM. Thirty rats were divided into three groups: normal control, DCM, and DCM+RES groups. DCM was induced by high-fat diet and streptozotocin (STZ) intraperitoneal injection, the rats in DCM+RES group received RES gavage for 16 weeks. RES improved the insulin resistance, and reduced the level of triglyceride, cholesterol, and low density lipoprotein cholesterol (LDLc) in DCM rats (all P < 0.05). Echocardiographic and hemodynamic studies revealed that RES treatment reversed the impaired diastolic and systolic cardiac function in DCM rats. Meanwhile, RES improved myocardial structural disorder and fibrosis, reserved mitochondrial membrane potential level (P < 0.05), and suppressed myocardial apoptosis in DCM rats (P < 0.05). Myocardial mitochondrial respiratory enzyme activities were improved by RES treatment in DCM rats (P < 0.05), accompanied with attenuated reactive oxygen species (ROS) generation (P < 0.05). The expression of UCP2 was further increased by RES treatment both in the myocardium of DCM rats (P < 0.05) and in the H9c2 cardiomyocytes incubated with high-glucose (P < 0.05). The protective effects of RES on high glucose-induced ROS generation, MPTP opening, Cyto c release, and cell apoptosis were all blunted by inhibiting the expression of UCP2 (all P < 0.05). In conclusion, RES treatment improved cardiac function and inhibited cardiomyocyte apoptosis, involving in ameliorating mitochondrial function in diabetic rats. UCP2 mediated the protective effects of RES on diabetic hearts.

Topics: Animals; Antioxidants; Apoptosis; Cardiotonic Agents; Cell Line; Cholesterol, LDL; Cytochromes c; Diabetes Mellitus, Experimental; Diabetic Cardiomyopathies; Diet, High-Fat; Gene Expression Regulation; Glucose; Insulin Resistance; Male; Membrane Potential, Mitochondrial; Mitochondria; Mitochondrial Membrane Transport Proteins; Mitochondrial Permeability Transition Pore; Myocardium; Myocytes, Cardiac; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Resveratrol; Streptozocin; Triglycerides; Uncoupling Protein 2

NLRP3 inflammasome activation plays an important role in diabetic cardiomyopathy (DCM), which may relate to excessive production of reactive oxygen species (ROS). Gypenosides (Gps), the major ingredients of Gynostemma pentaphylla (Thunb.) Makino, have exerted the properties of anti-hyperglycaemia and anti-inflammation, but whether Gps improve myocardial damage and the mechanism remains unclear. Here, we found that high glucose (HG) induced myocardial damage by activating the NLRP3 inflammasome and then promoting IL-1β and IL-18 secretion in H9C2 cells and NRVMs. Meanwhile, HG elevated the production of ROS, which was vital to NLRP3 inflammasome activation. Moreover, the ROS activated the NLRP3 inflammasome mainly by cytochrome c influx into the cytoplasm and binding to NLRP3. Inhibition of ROS and cytochrome c dramatically down-regulated NLRP3 inflammasome activation and improved the cardiomyocyte damage induced by HG, which was also detected in cells treated by Gps. Furthermore, Gps also reduced the levels of the C-reactive proteins (CRPs), IL-1β and IL-18, inhibited NLRP3 inflammasome activation and consequently improved myocardial damage in vivo. These findings provide a mechanism that ROS induced by HG activates the NLRP3 inflammasome by cytochrome c binding to NLRP3 and that Gps may be potential and effective drugs for DCM via the inhibition of ROS-mediated NLRP3 inflammasome activation.

Topics: Animals; Antioxidants; Blood Glucose; Cardiotonic Agents; Carrier Proteins; Cell Line; Cytochromes c; Diabetes Mellitus, Experimental; Diabetic Cardiomyopathies; Gene Expression Regulation; Gynostemma; Inflammasomes; Interleukin-18; Interleukin-1beta; Male; Myocytes, Cardiac; NLR Family, Pyrin Domain-Containing 3 Protein; Oxidative Stress; Plant Extracts; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Signal Transduction; Streptozocin

Apoptosis plays a critical role in the progression of diabetic cardiomyopathy (DC). Astragalus polysaccharides (APS), an extract of astragalus membranaceus (AM), is an effective cardioprotectant. Currently, little is known about the detailed mechanisms underlying cardioprotective effects of APS. The aims of this study were to investigate the potential effects and mechanisms of APS on apoptosis employing a model of high glucose induction of apoptosis in H9C2 cells.. A model of high glucose induction of H9C2 cell apoptosis was adopted in this research. The cell viabilities were analyzed by MTT assay, and the apoptotic response was quantified by flow cytometry. The expression levels of the apoptosis related proteins were determined by Real-time PCR and western blotting.. Incubation of H9C2 cells with various concentrations of glucose (i.e., 5.5, 12.5, 25, 33 and 44 mmol/L) for 24 h revealed that cell viability was reduced by high glucose dose-dependently. Pretreatment of cells with APS could inhibit high glucose-induced H9C2 cell apoptosis by decreasing the expressions of caspases and the release of cytochrome C from mitochondria to cytoplasm. Further experiments also showed that APS could modulate the ratio of Bcl-2 to Bax in mitochondria.. APS decreases high glucose-induced H9C2 cell apoptosis by inhibiting the expression of pro-apoptotic proteins of both the extrinsic and intrinsic pathways and modulating the ratio of Bcl-2 to Bax in mitochondria.

Topics: Apoptosis; Astragalus Plant; Caspases; Cell Line; Cytochromes c; Diabetic Cardiomyopathies; Glucose; Humans; Plant Extracts; Polysaccharides; Proto-Oncogene Proteins c-bcl-2; Signal Transduction

The upregulation of reactive oxygen species (ROS) is a primary cause of cardiomyocyte apoptosis in diabetes cardiomyopathy (DCM). Mitofusin-2 (Mfn-2) is a key protein that bridges the mitochondria and endoplasmic reticulum (ER). Hydrogen sulfide (H

Topics: Animals; Apoptosis; Blood Glucose; Blotting, Western; Cytochromes c; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 1; Diabetic Cardiomyopathies; Endoplasmic Reticulum; Endoplasmic Reticulum Stress; Fluorescent Antibody Technique; Gasotransmitters; GTP Phosphohydrolases; Heart; Hydrogen Sulfide; In Situ Nick-End Labeling; Male; Membrane Proteins; Microscopy, Electron; Mitochondria, Heart; Mitochondrial Proteins; Myocardium; Myocytes, Cardiac; Rats; Rats, Wistar; Sulfides