Diabetic Rat Hearts Research Articles

Flavonoid-rich fraction of Monodora tenuifolia Benth seeds improves antioxidant status in male Wistar rats with streptozotocin-induced Diabetes mellitus

BackgroundOxidative stress is a disruption in the balance between free radicals and the body's natural defenses. This study investigated the modulatory effect of a flavonoid-rich fraction of Monodora tenuifolia seed (FRFMTS) on oxidative stress and antioxidant enzymes in diabetic Wistar rats. The plant seeds were collected, and identified then, hydro-ethanolic extract was obtained with 80 % (v/v) ethanol and partitioned with solvents to obtain the FRFMTS. Diabetes mellitus was induced with a single dose of 40 mg/kg bwt streptozotocin and the rats were treated according to their grouping; group 1: non-diabetic control, groups 2 and 3: non-diabetic treated with 25 mg/kg FRFMTS and 50 mg/kg FRFMTS, respectively. Group 4: diabetic control group, groups 5 and 6: diabetic groups treated with 25 mg/kg and 50 mg/kg FRFMTS, respectively, while group 7: diabetic treated with 6.67 mg/kg metformin. Antioxidant status, oxidative stress biomarkers and activities of antioxidant enzymes were determined in plasma, heart, and kidney tissues using established procedures. ResultsPlasma total antioxidant status (TAS) was increased significantly (p < 0.05) in diabetic rats upon treatment with 25 mg/kg FRFMTS (70.4 %), while 50 mg/kg FRFMTS increased TAS by 70 %. The activities of glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD) in the plasma, heart, and kidney of diabetic rats significantly decreased (61.3 %, 58.8 % and 31.4 % respectively) while lipid peroxidation (LPO) was elevated when compared with normal control groups. Flavonoid-rich fraction of M. tenuifolia at 25 mg/kg bwt and 50 mg/kg bwt significantly increased the activity GPx enzyme by 32.3 % and 72 % in plasma, while there was no significant differences in both kidney and heart of diabetic rats when compared with diabetic control groups. The treatment of diabetic rats with 25 mg/kg FRFMTS and 50 mg/kg FRFMTS improved SOD activity in the plasma (51.5 % and 69.8 %), heart (32.3 % and 27.6 %) and kidney (31.4 % and 27.1 %) respectively, and CAT activity in plasma (44.2 % and 57 %), heart (28.6 % and 60 %) and kidney (69.6 % and 76.7 %) respectively. The concentration of malondialdehyde (MDA) in lipid peroxidation assay in the heart and kidney of diabetic rats treated with 25 mg/kg FRFMTS and 50 mg/kg FRFMTS reduced significantly by (62.5 % and 71.1 % in heart), while 50 mg/kg FRFMTS significantly reduced MDA in kidney by 43.8 %. ConclusionsThe results showed that FRFMTS reduces oxidative stress and enhances the activities of antioxidant enzymes in STZ-diabetic Wistar rats. As such, FRFMTS could be useful in the management of oxidative stress-mediated diabetic complications.

Assessment of efficacy of chrysin in diabetes-associated cardiac complications in chick embryo and murine model.

Patients with type 2 diabetes or prolonged diabetic condition are webbed into cardiac complications. This study aimed to ascertain the utility of chick embryo as an alternative to the mammalian model for type 2 diabetes-induced cardiac complications and chrysin as a protective agent. Diabetes was activated in ovo model (chick embryo) using glucose along with β-hydroxybutyric acid. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, Alamar, and Kenacid blue assay were used to compare with chrysin-administered group. Blood glucose level, total cholesterol, triglyceride, and high-density lipoprotein were considered as endpoints. Diabetes was induced in Wistar albino rats by administering a high-fat diet and a subdued dose of streptozotocin (35 mg/kg, b.w). Percentage of glycated hemoglobin, creatinine kinase-MB, tumor necrosis factor-α, and C-reactive protein were evaluated and compared with chrysin administered group. Chrysin treatment improved elevated blood glucose levels and dyslipidemia in a diabetic group of whole embryos. Condensed cellular growth and protein content as well as enhanced cytotoxicity in ovo were shielded by chrysin. Chrysin reduced cardiac and inflammatory markers in diabetic rats and provided cellular protection to damage the heart of diabetic rats. The protective action of chrysin in ovo model induced a secondary complication associated with diabetes, evidenced that the ovo model is an effective alternative in curtailing higher animal use in scientific research.

Ginsenoside Rb1 reduces oxidative/carbonyl stress damage and dysfunction of RyR2 in the heart of streptozotocin-induced diabetic rats

BackgroundOxidative stress may contribute to cardiac ryanodine receptor (RyR2) dysfunction in diabetic cardiomyopathy. Ginsenoside Rb1 (Rb1) is a major pharmacologically active component of ginseng to treat cardiovascular diseases. Whether Rb1 treat diabetes injured heart remains unknown. This study was to investigate the effect of Rb1 on diabetes injured cardiac muscle tissue and to further investigate its possible molecular pharmacology mechanisms.MethodsMale Sprague-Dawley rats were injected streptozotocin solution for 2 weeks, followed 6 weeks Rb1 or insulin treatment. The activity of SOD, CAT, Gpx, and the levels of MDA was measured; histological and ultrastructure analyses, RyR2 activity and phosphorylated RyR2(Ser2808) protein expression analyses; and Tunel assay were performed.ResultsThere was decreased activity of SOD, CAT, Gpx and increased levels of MDA in the diabetic group from control. Rb1 treatment increased activity of SOD, CAT, Gpx and decreased the levels of MDA as compared with diabetic rats. Neutralizing the RyR2 activity significantly decreased in diabetes from control, and increased in Rb1 treatment group from diabetic group. The expression of phosphorylation of RyR2 Ser2808 was increased in diabetic rats from control, and were attenuated with insulin and Rb1 treatment. Diabetes increased the apoptosis rate, and Rb1 treatment decreased the apoptosis rate. Rb1 and insulin ameliorated myocardial injury in diabetic rats.ConclusionsThese data indicate that Rb1 could be useful for mitigating oxidative damage, reduced phosphorylation of RyR2 Ser2808 and decreased the apoptosis rate of cardiomyocytes in diabetic cardiomyopathy.

Cardio- and Hepatoprotective Effects of Hydrogen Sulfide in a High-Fat Diet and Low-Dose Streptozotocin-Induced Type 2 Diabetic Rats

Background: Hydrogen sulfide (H2 S) is the third most crucial gas that is produced inside the body, and at physiological levels, it increases a wide range of health properties, such as anti-inflammatory antioxidant effects. Objectives: This study aimed at evaluating the impact of H2 S administration on oxidative stress (OS) in the heart and liver tissues of diabetic rats. Methods: Twenty-eight Wistar rats were randomly divided into 4 groups, namely, the healthy control group, the diabetic group, and diabetic groups treated with 50 µM/kg and 100 µM/kg of H2 S. After 60 days of treatment, the animals were sacrificed, and biochemical and OS markers were determined using colorimeter methods. In addition, the liver tissue underwent histological assessment. Results: The findings revealed that H2 S controlled the weight of rats and significantly decreased fasting blood sugar (FBS) in the treatment group with a dose of 50 µM/kg and 100 µM/kg (P&lt;0.05) compared to the diabetic animals. Further, insulin concentration and insulin resistance in the H2 S 100 µM/kg group decreased in comparison to the diabetic group (P&lt;0.05). The levels of triglyceride, cholesterol, atherogenic index, and low-density lipoprotein in H2 S-treated animals were markedly lower than in the diabetic group (P&lt;0.05). The results of OS parameters demonstrated that H2 S 100 µM/kg reduced the malondialdehyde in the heart tissue compared to the diabetic group (P&lt;0.05). The histological assessment also confirmed the effectiveness of H2 S in improving liver morphology and parenchymal structure. Conclusion: According to the results of this study, H2 S can be considered a suitable therapeutic agent to prevent diabetes complications.

Sílybum Mariánum’s Impact on Physiological Alterations and Oxidative Stress in Diabetic Rats

This study delves into the crucial role of oxidative stress in non-infectious diseases and emphasizes the necessity of precise control over cellular oxidative processes using both natural and external antioxidant systems. Dysfunctions in these systems often result in various pathologies, underscoring the therapeutic promise of antioxidants in restoring cellular balance. Sílybum mariánum, known for its multifaceted biological properties such as antioxidative, hepatoprotector, anti - toxic, and organ-protective effects, emerges as a compelling subject for investigating its mechanisms, particularly in diabetes mellitus. Our research examines the impact of Sílybum mariánum's ethanolic extract on oxidative stress levels in alloxan-induced diabetic conditions. Our results demonstrate significant antioxidant effects of the extract on the heart and aorta preparations in diabetic rats. This study adds to the expanding body of research on the potential therapeutic utility of Sílybum mariánum in addressing oxidative stress-related complications linked with diabetes mellitus.

Cardiac Oxidative Status in Diabetic Wistar Rats Exposed To Ethanol Extract of Cucumis Sativus Fruit

The present study investigated cardiac oxidative status in diabetic Wistar rats exposed to ethanol extract of Cucumis sativus fruit. Male Wistar albino rats (n = 25, mean weight = 215 ± 15 g) were randomly assigned to five groups of 5 rats each: normal control, diabetic control, metformin, extract (200 mg/kg body weight, bwt) and extract (300 mg/kg bwt) groups. Diabetes mellitus was induced in the rats via intraperitoneal injection of 50 mg/kg bwt STZ. The diabetic rats were treated for 21 days with either metformin (50 mg/kg bwt) or the extract. Activities of antioxidant enzymes such as catalase, superoxide dismutase (SOD), glutathione peroxidase (GPx) and glutathione reductase (GR) as well as molecules like reduced glutathione (GSH), total protein (TP), malondialdehyde (MDA) and nitric oxide (NO) were measured in heart homogenate. The results showed that induction of diabetes mellitus with STZ significantly increased the fasting blood glucose (FBG) concentrations of the rats, while decreasing the activity/concentration of antioxidant enzymes/ molecules (p &lt; 0.05). However, treatment of the diabetic Wistar rats with the extract markedly reduced the FBG concentration and body weights of rats, but enhanced the activity/concentration of antioxidant enzymes/molecules in cardiac tissue (p &lt; 0.05). These results indicate that ethanol extract of the medicinal plant fruit has the potential to promote antioxidant defense in the heart of STZ-induced diabetic rats.

Duodenal-jejunal bypass surgery activates eNOS and enhances antioxidant system by activating AMPK pathway to improve heart oxidative stress in diabetic cardiomyopathy rats.

Diabetic cardiomyopathy is a serious complication of obesity with type 2 diabetes and is a major cause of mortality. Metabolic surgery, such as duodenal-jejunal bypass (DJB), can effectively improve diabetic cardiomyopathy; however, the underlying mechanisms remain elusive. Oxidative stress is one of the pivotal mechanisms of diabetic cardiomyopathy. Our objective was to investigate the effect and potential mechanisms of DJB on oxidative stress in the heart of diabetic cardiomyopathy rats. High-fat diet combined with intraperitoneal injection of streptozotocin was used to establish diabetic cardiomyopathy rats. DJB was performed on diabetic cardiomyopathy rats, and high glucose and palmitate were used to simulate diabetic cardiomyopathy in H9C2 cells in vitro. Sera from different groups of rats were used for experiments in vivo and in vitro. DJB effectively improved oxidative stress and activated the adenosine monophosphate (AMP)-activated protein kinase (AMPK) pathway to increase endothelial nitric oxide synthase (eNOS) phosphorylation level and the expression of antioxidative system-related proteins and genes in the heart of diabetic cardiomyopathy rats. AMPK agonists and serum from DJB rats activated the AMPK pathway to increase eNOS phosphorylation level and the expression of antioxidative system-related proteins and genes and decreased the content of reactive oxygen species in H9C2 cells, but this improvement was almost eliminated by the addition of AMPK inhibitors. DJB activates eNOS and enhances the antioxidant system by activating the AMPK pathway-and not solely by improving blood glucose-to improve oxidative stress in the heart of diabetic cardiomyopathy rats.

Chrysin restores the cardioprotective effect of ischemic preconditioning in diabetes-challenged rat heart

BackgroundIschemic preconditioning (IPC) is the utmost capable design to achieve protection over ischemia-reperfusion injury (I/R), but this phenomenon gets attenuated during various pathological conditions like diabetes. Chrysin exhibits cardioprotection in various experiments however, its therapeutic potential on IPC-mediated cardioprotection via PI3K-Akt-eNOS pathway in streptozotocin (STZ) triggered diabetes-challenged rat heart is yet to be assessed. For that reason, the experiment has been planned to investigate chrysin's effect on the cardioprotective action of IPC involving the PI3K-Akt-eNOS cascade in rat hearts challenged to diabetes. MethodsThe project was accomplished through means of absorbance studies for biochemical parameters, infarct size measurement (TTC stain) and coronary flow. ResultsThe findings of the present study revealed that STZ drastically augmented the serum glucose level and the chrysin significantly reversed the IPC-stimulated increased coronary flow, nitrite release, and reduced LDH (lactate dehydrogenase), CK-MB (creatine kinase) activities as well as infarct size in diabetes-induced rat heart. Furthermore, chrysin also reversed the IPC-induced reduction in oxidative stress in an isolated Langendorff's perfused diabetic rat heart. Moreover, four episodes of preconditioning by either PI3K or eNOS inhibitor in chrysin-pretreated diabetic rat hearts significantly abolished the protective effect of chrysin. ConclusionConsequently, these observations suggested that chrysin increases the therapeutic efficiency of IPC in mitigating I/R injury via PI3K-Akt-eNOS signalling in diabetes-challenged rat hearts. Hence, chrysin could be a potential alternative option to IPC in diabetic rat hearts.

Involvement Of Inula Racemose Hook Extract on Ischemic Preconditioning Mediated Cardioprotection in Diabetes

Objective: Ischemia of the heart is one of the major cause behind diabetes mediate death in peoples. PI3K/Akt phosphorylation is inhibited in IPC-induced infarcts, preventing the opening of the mitochondrial permeability transition pore (MPTP). In diabetics, the beneficial effects are lessened. IPC-mediated cardioprotection in diabetic Wistar rat hearts was observed in this study after pre-treatment with Inula racemosa Hook root extract (IrA). Ischemia reperfusion (I / R) and cycles of IPC were performed on an isolated rat heart mounted on Langendorff's assembly. MPTP is opened by atractyloside (ATR). Method: RP-HPLC and 1H and 13C NMR were used to identify the chemical components. Western blot, oxidative stress, mitochondrial function, integrity, and haemodynamic parameters are all examined in this study. Result: Pretreatment with IrA reduced LDH, CKMB, myocardial infarction size, ventricular fibrillation, and cardiac collagen content, as well as decreased oxidative stress levels and mitochondrial dysfunction in diabetic rat hearts in all groups, according to the data. By blocking the opening of MPTP in diabetic rats, ATR reduced the cardioprotective effect of IrA on IPC. Conclusion: This shows that IPC-mediated cardioprotection can be restored by pre-treatment with IrA, which inhibits the opening of the MPTP in diabetic rats.

Antioxidant Activity and Protective Effects of an Oxovanadium (IV) Complex on Heart and Aorta Injury of STZ-Diabetic Rats.

Diabetic people have a much higher rate of cardiovascular disease than healthy people. Therefore, heart and aortic tissues are target tissues in diabetic research. In recent years, the synthesis of new vanadium complexes and investigation of their antidiabetic/lowering effect on the blood glucose levels and antioxidant properties are increasing day by day. Our study aimed to examine the effects of synthesized oxovanadium (IV) complex of 2-[(2,4-dihydroxybenzylidene]hydrazine-1-[(N-(2-hydroxybenzylidene)](S-methyl)carbothioamide [VOL] on diabetic heart and aortic tissues, as well as in vitro lactate dehydrogenase (LDH) and myeloperoxidase (MPO) inhibition, antioxidant properties, and reducing power. Electrochemical characterization of the VOL was carried out by using Cyclic Voltammetry (CV) and Linear Sweep Voltammetry (LSV) methods. In addition, in silico drug-likeness and ADME prediction were also investigated. For in vivo study, male Swiss albino rats were randomly selected and separated into four groups which are control, control + VOL, diabetic and diabetic + VOL. After the experimental procedure, biochemical parameters were investigated in homogenates of heart and aorta tissues. The results showed that VOL has a protective effect on heart and aortic tissue against oxidative stress. According to electrochemical experiments, one reversible oxidative couple and one irreversible reductive response were observed for the complex. In addition, in vitro LDH and MPO inhibition of VOL was examined. It was found that VOL had a protective effect on heart and aortic tissues of diabetic rats, and caused the inhibition of LDH and MPO in in vitro studies. On the other hand, evaluating the synthesized VOL according to in silico drug-likeness and absorption, distribution, metabolism, and excretion (ADME) prediction, it was found that VOL has drug-like properties and exhibited high gastrointestinal absorption. The VOL had a therapeutic impact on the heart and aortic tissues of diabetic rats, according to the findings.

Abstract P1162: Nedd4-2 Inactivation Underlies The Increase In Cardiac Sodium-dependent Glucose Cotransporter-1 In Diabetic Hearts

Rationale: Type-2 diabetes (T2D) is a major risk factor for developing heart failure. While the underlying mechanisms are poorly understood, recent evidence suggests that upregulation of the Na + /glucose cotransporter 1 (SGLT1) plays an important role, as it causes myocyte Na + overload. Objective: To identify the mechanisms involved in promoting an increase in SGLT1 protein level in diabetic hearts. Methods/Results: We compared hearts from patients with and without T2D and hearts from rats with late-onset T2D caused by overexpression of human amylin in pancreatic β-cells versus hearts from wild-type littermates. SGLT1 protein level was significantly higher in hearts from both humans and rats with T2D. In contrast, the SGLT1 mRNA levels were comparable in hearts from T2D and non-diabetic patients and rats. This result suggests that theT2D-induced increase in cardiac SGLT1 protein occurs at a post-transcriptional level. Co-immunoprecipitation of SGLT1 with ubiquitin was reduced in diabetic human and rat hearts, which indicates that SGLT1 degradation is impaired. The E3 ubiquitin ligase Nedd4-2 is responsible for ubiquitination of several cardiac membrane transporters. Pharmacological inhibition of Nedd4-2 with Heclin in HL-1 cells resulted in significantly higher SGLT1 protein levels, suggesting that Nedd4-2 also mediates SGLT1 degradation. Nedd4-2 is inactivated upon phosphorylation by several kinases, including the serum and glucocorticoid-regulated kinase-1 (SGK1). Using western blotting, we found increased Nedd4-2 phosphorylation in hearts from humans and rats with T2D compared to their non-diabetic counterparts. Moreover, hearts from T2D patients exhibited higher levels of SGK1 and its activated phosphorylated form compared to their non-diabetic counterparts. Conclusion/New Hypothesis: The increase in SGLT1 protein in the diabetic heart is regulated post-transcriptionally by an impairment in Nedd4-2 dependent ubiquitination and degradation of SGLT1.

Pioglitazone Alters Ace/Ace 2 Balance to Favour Ace2 Independently Of Glycaemia Levels in Diabetic Rat Heart.

The activation of the renin-angiotensin system (RAS) contributes to the pathogenesis of cardiac damage during diabetes. In the present study, we investigated the role of pioglitazone, dapagliflozin and their combination on RAS components in streptozotocin-induced diabetic cardiomyopathy in Wistar rats. Blood glucose, serum lipids, and ACE (angiotensin-converting enzyme), ACE2 levels were determined. mRNA levels of Myh6 (myosins heavy chain), Myh7, Ace, Ace2, Nppa, Nppb (natriuretic peptide A, B) and Ppars (peroxisome proliferator activating receptors) genes in the heart were determined by real-time PCR (polymerase chain reaction). Protein expression of ACE and ACE2 was assessed by western blotting. After six weeks pioglitazone suppressed Ace mRNA and protein levels (p<0.05) and modified the Ace/Ace2 ratio (p<0.05) in the cardiac tissue of diabetic rats. Pioglitazone significantly decreased serum lipids (p<0.05) but did not significantly influence blood glucose and ACE serum levels of diabetic animals. Dapagliflozin had a significant glucose-lowering action (p<0.05) however, it had no impact on the Ace/Ace2 ratio. The combination of both compounds markedly improved blood glucose (p<0.05) as well as the Myh6/Myh7 ratio (p<0.05) but had no further impact on the Ace to Ace2 balance in cardiac tissue compared to pioglitazone monotherapy. We found that pioglitazone improves the cardiac Ace/ Ace2 ratio in diabetic rats suggesting a potential cardioprotective effect. This effect is independent of its antidiabetic and metabolic effects.

PPAR-Α agonist fenofibrate and 11,12-epoxyeicosatrienoic acid suppresses endoplasmic reticulum stress-induced apoptosis and enhances cell viability in diabetic rat hearts

PPAR-Α agonist fenofibrate and 11,12-epoxyeicosatrienoic acid suppresses endoplasmic reticulum stress-induced apoptosis and enhances cell viability in diabetic rat hearts

Correction to: Basic fibroblast growth factor alleviates metabolic abnormalities in the heart of streptozotocin-induced diabetic rats

Correction to: Basic fibroblast growth factor alleviates metabolic abnormalities in the heart of streptozotocin-induced diabetic rats

Maternal diabetes increases FOXO1 activation during embryonic cardiac development

Maternal diabetes is known to affect heart development, inducing the programming of cardiac alterations in the offspring's adult life. Previous studies in the heart of adult offspring have shown increased activation of FOXO1 (a transcription factor involved in a wide variety of cellular functions such as apoptosis, cellular proliferation, reactive oxygen species detoxification, and antioxidant and pro-inflammatory processes) and of target genes related to inflammatory and fibrotic processes. In this work, we aimed to evaluate the effects of maternal diabetes on FOXO1 activation as well as on the expression of target genes relevant to the formation of the cardiovascular system during organogenesis (day 12 of gestation). The embryonic heart from diabetic rats showed increased active FOXO1 levels, reduced protein levels of mTOR (a nutrient sensor regulating cell growth, proliferation and metabolism) and reduced mTORC2-SGK1 pathway, which phosphorylates FOXO1. These alterations were related to increases in the levels of 4-hydroxynonenal (an oxidative stress marker) and increased mRNA levels of inducible nitric oxide synthase, angiopoietin-2 and matrix metalloproteinase-2 (MMP2) (all FOXO1 target genes relevant for cardiac development). Results also showed increased extracellular and intracellular immunolocalization of MMP2 in the myocardium and its projection into the lumen of the cavity (trabeculations) together with decreased immunostaining of connexin 43, a protein relevant for cardiac function that is target of MMP2. In conclusion, increases in active FOXO1 induced by maternal diabetes initiate early during embryonic heart development and are related to increases in markers of oxidative stress and of proinflammatory cardiac development, as well to an altered expression of proteolytic enzymes that regulate connexin 43. These alterations may lead to an altered programming of cardiovascular development in the embryonic heart of diabetic rats.

Mitochondrial H2O2 metabolism as central event of heart complex I syndrome in early diabetes.

Hydrogen peroxide is the main metabolite effective in redox regulation and it is considered an insulinomimetic agent, with insulin signalling being essential for normal mitochondrial function in cardiomyocytes. Therefore, the aim of this work was to deeply analyse the heart mitochondrial H2O2 metabolism, in the early stage of type 1 diabetes. Diabetes was induced by Streptozotocin (STZ, single dose, 60mg×kg-1, ip.) in male Wistar rats and the animals were sacrificed 10 days after injection. Mitochondrial membrane potential and ATP production, using malate-glutamate as substrates, in the heart of diabetic animals were like the ones observed in control group. Mn-SOD activity was lower (15%) in the heart of diabetic rats even though its expression was increased (29%). The increment in heart mitochondrial H2O2 production (117%) in diabetic animals was accompanied by an enhancement in the activities and expressions of glutathione peroxidase (26% and 42%) and of catalase (200% and 133%), with no changes in the peroxiredoxin activity, leading to [H2O2]ss ∼40nM. Heart mitochondrial lipid peroxidation and protein nitration were higher in STZ-injected animals (45% and 42%) than in control group. The mitochondrial membrane potential and ATP production preservation suggest the absence of irreversible damage at this early stage of diabetes 1. The increase in mitochondrial [H2O2]ss above the physiological range, but still below supraphysiological concentration (∼100nM) seems to be part of the adaptive response triggered in cardiomyocytes due to the absence of insulin. The signs of mitochondrial dysfunction observed in this very early stage of diabetes are consistent with the mitochondrial entity called ″complex I syndrome″.

Epigenetic modifier alpha-ketoglutarate modulates aberrant gene body methylation and hydroxymethylation marks in diabetic heart

BackgroundDiabetic cardiomyopathy (DCM) is a leading cause of death in diabetic patients. Hyperglycemic myocardial microenvironment significantly alters chromatin architecture and the transcriptome, resulting in aberrant activation of signaling pathways in a diabetic heart. Epigenetic marks play vital roles in transcriptional reprogramming during the development of DCM. The current study is aimed to profile genome-wide DNA (hydroxy)methylation patterns in the hearts of control and streptozotocin (STZ)-induced diabetic rats and decipher the effect of modulation of DNA methylation by alpha-ketoglutarate (AKG), a TET enzyme cofactor, on the progression of DCM.MethodsDiabetes was induced in male adult Wistar rats with an intraperitoneal injection of STZ. Diabetic and vehicle control animals were randomly divided into groups with/without AKG treatment. Cardiac function was monitored by performing cardiac catheterization. Global methylation (5mC) and hydroxymethylation (5hmC) patterns were mapped in the Left ventricular tissue of control and diabetic rats with the help of an enrichment-based (h)MEDIP-sequencing technique by using antibodies specific for 5mC and 5hmC. Sequencing data were validated by performing (h)MEDIP-qPCR analysis at the gene-specific level, and gene expression was analyzed by qPCR. The mRNA and protein expression of enzymes involved in the DNA methylation and demethylation cycle were analyzed by qPCR and western blotting. Global 5mC and 5hmC levels were also assessed in high glucose-treated DNMT3B knockdown H9c2 cells.ResultsWe found the increased expression of DNMT3B, MBD2, and MeCP2 with a concomitant accumulation of 5mC and 5hmC, specifically in gene body regions of diabetic rat hearts compared to the control. Calcium signaling was the most significantly affected pathway by cytosine modifications in the diabetic heart. Additionally, hypermethylated gene body regions were associated with Rap1, apelin, and phosphatidyl inositol signaling, while metabolic pathways were most affected by hyperhydroxymethylation. AKG supplementation in diabetic rats reversed aberrant methylation patterns and restored cardiac function. Hyperglycemia also increased 5mC and 5hmC levels in H9c2 cells, which was normalized by DNMT3B knockdown or AKG supplementation.ConclusionThis study demonstrates that reverting hyperglycemic damage to cardiac tissue might be possible by erasing adverse epigenetic signatures by supplementing epigenetic modulators such as AKG along with an existing antidiabetic treatment regimen.

THE INFLUENCE OF MELATONIN ON THE ACTIVITY OF THE MAIN ENZYMES OF ANTIOXIDANT PROTECTION IN THE HEART OF RATS WITH DEXAMETHASONE DIABETES

The goal of this study was to find out the influence of melatonin on the content of TBCreactive products; on the activity of the main antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) in the heart of rats with dexamethasone diabetes. Materials and Methods. The experimental study was carried out on thirty male eighteen-month-old non-linear white rats. The experimental animals were divided into three groups: 1) control (intact animals); 2) rats with diabetes; 3) rats to which, in addition to dexamethasone, melatonin in a dose of 10 mg per kg of body weight was administered intragastrically daily through a metal probe during the 13 days of experiment. Results. In the heart of rats with dexamethasone diabetes, the content of TBC-reactive products increases by 43% compared with control rats, which indicates an increase in the processes of free radical oxidation of lipids. At the same time, in the heart of diabetic rats, a decrease in the activity of the studied enzymes is noted: superoxide dismutase – by 28%, catalase – by 25%, and glutathione peroxidase – by 31%, respectively, compared with control rats. In the heart of rats, which, in addition to dexamethasone injections, received melatonin, the studied indicators did not differ reliably from the indicators of the control group of animals. Conclusions. The use of melatonin stopped the processes of free radical oxidation of lipids and restored the activity of the investigated enzymes of antioxidant protection in the heart of rats.

Downregulation of extramitochondrial BCKDH and its uncoupling from AMP deaminase in type 2 diabetic OLETF rat hearts.

Systemic branched-chain amino acid (BCAA) metabolism is dysregulated in cardiometabolic diseases. We previously demonstrated that upregulated AMP deaminase 3 (AMPD3) impairs cardiac energetics in a rat model of obese type 2 diabetes, Otsuka Long-Evans-Tokushima fatty (OLETF). Here, we hypothesized that the cardiac BCAA levels and the activity of branched-chain α-keto acid dehydrogenase (BCKDH), a rate-limiting enzyme in BCAA metabolism, are altered by type 2 diabetes (T2DM), and that upregulated AMPD3 expression is involved in the alteration. Performing proteomic analysis combined with immunoblotting, we discovered that BCKDH localizes not only to mitochondria but also to the endoplasmic reticulum (ER), where it interacts with AMPD3. Knocking down AMPD3 in neonatal rat cardiomyocytes (NRCMs) increased BCKDH activity, suggesting that AMPD3 negatively regulates BCKDH. Compared with control rats (Long-Evans Tokushima Otsuka [LETO] rats), OLETF rats exhibited 49% higher cardiac BCAA levels and 49% lower BCKDH activity. In the cardiac ER of the OLETF rats, BCKDH-E1α subunit expression was downregulated, while AMPD3 expression was upregulated, resulting in an 80% lower AMPD3-E1α interaction compared to LETO rats. Knocking down E1α expression in NRCMs upregulated AMPD3 expression and recapitulated the imbalanced AMPD3-BCKDH expressions observed in OLETF rat hearts. E1α knockdown in NRCMs inhibited glucose oxidation in response to insulin, palmitate oxidation, and lipid droplet biogenesis under oleate loading. Collectively, these data revealed previously unrecognized extramitochondrial localization of BCKDH in the heart and its reciprocal regulation with AMPD3 and imbalanced AMPD3-BCKDH interactions in OLETF. Downregulation of BCKDH in cardiomyocytes induced profound metabolic changes that are observed in OLETF hearts, providing insight into mechanisms contributing to the development of diabetic cardiomyopathy.

Histological investigation of aqueous extract of cactus on the heart of diabetic Wistar rats

This study aimed to examine the effects of aqueous leaf extract of Cactus on the Heart of Diabetic Wistar Rats. Thirty adult male Wistar rats weighing between (160-200) g were randomly grouped into five consisting of six rats each viz: A. normal control, B. diabetic only, C. diabetic treated with Cactus, and D. diabetes treated with Metformin only, and E. Cactus extract only. Diabetes was induced by a single intraperitoneal injection of Streptozotocin of 70mg/kg/body weight. After 72 hours of uninterrupted diabetes (blood glucose≥ 7 mmol), aqueous extracts of Cactus and Metformin were administered orally at 100 mg/kg body weight daily for four weeks and blood glucose level was recorded weekly. After four weeks of extract administration, animals were sacrificed by euthanasia. Organs were weighed and their weight was recorded. Data were analyzed using excel and one-way ANOVA. The findings of this study showed that the blood glucose level of Diabetic +Cactus group and diabetes + Metformin were significant when compared to the diabetic group (p&lt;0.05). The body weight and relative organ weight of the Diabetic +Cactus group and diabetes+ Metformin when compared to the diabetic group was significant P&lt;0.05. Histological findings showed a normal control group had normal histoarchitecture with numerous healthy cardiomyocytes and normal distribution of collagen. Diabetic groups showed many degenerating cardiomyocytes and numerous depositions of collagen. Diabetes +Cactus and Metformin treated groups showed little disruption. Aqueous extract of Cactus showed ameliorative effects on the heart of adult male Wistar rats against the damage initiated by diabetes.