cytochrome-c-t and Insulin-Resistance

The mitochondrial electron transport chain (ETC) plays a central role in energy generation in the cell. Mitochondrial dysfunctions diminish adenosine triphosphate (ATP) production and result in insufficient energy to maintain cell function. As energy output declines, the most energetic tissues are preferentially affected. To satisfy cellular energy demands, the mitochondrial ETC needs to be able to elevate its capacity to produce ATP at times of increased metabolic demand or decreased fuel supply. This mitochondrial plasticity is reduced in many age-associated diseases. In this review, we describe the serendipitous discovery of a novel class of compounds that selectively target cardiolipin on the inner mitochondrial membrane to optimize efficiency of the ETC and thereby restore cellular bioenergetics in aging and diverse disease models, without any effect on the normal healthy organism. The first of these compounds, SS-31, is currently in multiple clinical trials.

Topics: Adenosine Triphosphate; Aging; Burns; Cardiolipins; Cytochromes c; Drug Discovery; Electron Transport; Energy Metabolism; Heart Failure; Humans; Insulin Resistance; Mitochondria; Myocardial Reperfusion Injury; Oligopeptides

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

Polycystic ovary syndrome (PCOS) is a common endocrine disorder with unknown etiology and unsatisfactory clinical treatment. Considering the ethical limitations of studies involving humans, animal models that reflect features of PCOS and insulin resistance (IR) are crucial resources in investigating this syndrome. Our previous study showed that mitochondrial dysfunction resulted from pathogenic mutations of mitochondrial DNA (mtDNA), and that oxidative stress had an active role in the phenotypic manifestation of PCOS‑IR. Therefore, it was hypothesized that limiting oxidative stress and mitochondrial damage may be useful and effective for the clinical treatment of PCOS‑IR. For this purpose, the present study examined the therapeutic effects of the mitochondria‑targeted antioxidant MitoQ10 for PCOS‑IR. Furthermore, the histopathology was used to analysis the ovarian morphological changes. The endocrine and reproductive related parameters were analyzed by ELISA approach. A PCOS‑IR model was successfully established by subcutaneous injection of rats with testosterone propionate and feeding a high‑fat diet. The 30 female Sprague‑Dawley rats were then divided into three groups, comprising a control (n=10), animal model (PCOS‑IR, n=10) and MitoQ10 treatment (n=10) group. It was found that MitoQ10 significantly improved the IR condition and reversed the endocrine and reproductive conditions of PCOS. In addition, the impaired mitochondrial functions were improved following MitoQ10 administration. Notably, western blot results suggested that this antioxidant reduced the expression levels of apoptosis‑related proteins cytochrome c and B‑cell lymphoma‑2 (Bcl‑2)‑associated X protein, whereas the anti‑apoptotic protein Bcl‑extra large was increased following MitoQ10 treatment. Taken together, the data indicated that the MitoQ10 may have a beneficial favorable therapeutic effect on animals with PCOS‑IR, most likely via the protection of mitochondrial functions and regulation of programmed cell death‑related proteins.

Topics: Animals; Antioxidants; bcl-2-Associated X Protein; bcl-X Protein; Biomarkers; Cytochromes c; Disease Models, Animal; Endocrine System; Female; Hormones; Insulin Resistance; Mitochondria; Oxidative Stress; Polycystic Ovary Syndrome; Rats, Sprague-Dawley; Reproduction

A-type dimeric epigallocatechin-3-gallate (A-type-EGCG-dimer, AEd), a new proanthocyanidins dimer from persimmon fruits, has been shown to have health benefit effects. However, A-type-EGCG-dimer affects gluose metabolism in the liver and the underlying mechanism is not clarified. The present study aims to examine the protective effects of A-type-EGCG-dimer on Pb-induced hepatic insulin resistance, endoplasmic reticulum (ER) stress and apoptosis in rats. Male wistar rats exposed to 0.05% w/v Pb acetate in the drinking water with or without A-type-EGCG-dimer coadministration (200 mg/kg body weight/day, intragastrically) for three months. We found that A-type-EGCG-dimer and pioglitazone supplementation significantly deceased glucose and insulin levels in plasma as compared with the Pb group. A-type-EGCG-dimer markedly prevents Pb-induced oxidative stress, ER stress and apoptosis in livers. A-type-EGCG-dimer and pioglitazone reduced the expression levels of the GRP78, PEPCK, G6Pase, p-PERK, p-IRE1, p-JNK, ATF4, CHOP and increased p-AKT in livers of the Pb group. Moreover, A-type-EGCG-dimer reduced ROS production and restored the activities of SOD and GPx in livers. A-type-EGCG-dimer decreased Bax, cytosolic cytochrome c and cleaved caspase-3 and increased Bcl-2 in livers of Pb-exposed rats. Our results suggest that A-type-EGCG-dimer might be a potential natural candidate for the prevention of hepatic insulin resistance and apoptosis induced by Pb.

Topics: Animals; Apoptosis; Blood Glucose; Catechin; Cytochromes c; Dimerization; Diospyros; Endoplasmic Reticulum Chaperone BiP; Endoplasmic Reticulum Stress; Humans; Insulin; Insulin Resistance; Lead; Liver; Male; Metabolic Diseases; Oxidative Stress; Plant Extracts; Rats; Signal Transduction

In this study, we investigated the causal relationship between chronic cold exposure and insulin resistance and the mechanisms of how DNA methylation and histone deacetylation regulate cold-reduced insulin resistance. 46 adult male mice from postnatal day 90-180 were randomly assigned to control group and cold-exposure group. Mice in cold-exposure group were placed at temperature from -1 to 4 °C for 30 days to mimic chronic cold environment. Then, fasting blood glucose, blood insulin level and insulin resistance index were measured with enzymatic methods. Immunofluorescent labeling was carried out to visualize the insulin receptor substrate 2 (IRS2), Obese receptor (Ob-R, a leptin receptor), voltage-dependent anion channel protein 1 (VDAC1), cytochrome C (cytC), 5-methylcytosine (5-mC) positive cells in hippocampal CA1 area. Furthermore, the expressions of some proteins mentioned above were detected with Western blot. The results showed: ① Chronic cold exposure could reduce the insulin resistance index (P < 0.01) and increase the number of IRS2 positive cells and Ob-R positive cells in hippocampus (P < 0.01). ② The expressions of mitochondrial energy-relative proteins, VDAC1 and cytC, were higher in cold-exposure group than in control group with both immunohistochemical staining and Western blot (P < 0.01). ③ Chronic cold exposure increased DNA methylation and histone deacetylation in the pyramidal cells of CA1 area and led to an increase in the expression of histone deacetylase 1 (HDAC1) and DNA methylation relative enzymes (P < 0.01). In conclusion, chronic cold exposure can improve insulin sensitivity, with the involvement of DNA methylation, histone deacetylation and the regulation of mitochondrial energy metabolism. These epigenetic modifications probably form the basic mechanism of cold-reduced insulin resistance.

Topics: 5-Methylcytosine; Acetylation; Animals; Blood Glucose; Cold Temperature; Cytochromes c; DNA Methylation; Energy Metabolism; Epigenesis, Genetic; Histones; Insulin; Insulin Receptor Substrate Proteins; Insulin Resistance; Male; Mice; Mice, Inbred C57BL; Mitochondria; Protein Processing, Post-Translational; Receptors, Leptin; Voltage-Dependent Anion Channel 1

Increasing evidence has established causative links between obesity, chronic inflammation and insulin resistance; the core pathophysiological feature in type 2 diabetes mellitus. This study was designed to examine whether the combination of L-cysteine and metformin would provide additional benefits in reducing oxidative stress, inflammation and insulin resistance in streptozotocin-induced type 2 diabetes in rats. Male Wistar rats were fed a high-fat diet (HFD) for 8 weeks to induce insulin resistance after which they were rendered diabetic with low-dose streptozotocin. Diabetic rats were treated with metformin (300 mg/kg/day), L-cysteine (300 mg/kg/day) and their combination along with HFD for another 2 weeks. Control rats were fed normal rat chow throughout the experiment. At the end of treatment, fasting blood glucose, fasting serum insulin, homeostasis model assessment-insulin resistance index (HOMA-IR) and serum free fatty acids (FFAs) were measured. Serum levels of the inflammatory markers; monocyte chemoattractant protein-1 (MCP-1), C-reactive protein (CRP) and nitrite/nitrate were also determined. The liver was isolated and used for determination of malondialdehyde (MDA), reduced glutathione (GSH), caspase-3 and cytochrome c levels. The hypoglycemic effect of the combination therapy exceeded that of metformin and L-cysteine monotherapies with more improvement in insulin resistance. All treated groups exhibited significant reductions in serum FFAs, oxidative stress and inflammatory parameters, caspase-3 and cytochrome c levels compared to untreated diabetic rats with the highest improvement observed in the combination group. In conclusion, the present results clearly suggest that L-cysteine can be strongly considered as an adjunct to metformin in management of type 2 diabetes.

Topics: Animals; Body Weight; C-Reactive Protein; Caspase 3; Chemokine CCL2; Cysteine; Cytochromes c; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Drug Interactions; Fatty Acids, Nonesterified; Glutathione; Inflammation; Insulin Resistance; Liver; Male; Malondialdehyde; Metformin; Nitrates; Nitrites; Oxidative Stress; Rats; Rats, Wistar