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Our group previously demonstrated that an excess of nutrients, as observed in diabetes, provokes an increase in cardiac protein acetylation responsible for a reduced insulin-stimulated translocation of the glucose transporter GLUT4 to the plasma membrane. The acetylated proteins involved in this event have yet not been identified. α-Tubulin is a promising candidate as a major cytoskeleton component involved, among other things, in the translocation of GLUT4-containing vesicles from their intracellular pools toward the plasma membrane. Moreover, α-tubulin is known to be acetylated, Lys40 (K40) being its best characterized acetylated residue. The present work sought to evaluate the impact of α-tubulin K40 acetylation on cardiac glucose entry, with a particular interest in GLUT4 translocation. First, we observed that a mouse model of high-fat diet-induced obesity presented an increase in cardiac α-tubulin K40 acetylation level. We next showed that treatment of insulin-sensitive primary cultured adult rat cardiomyocytes with tubacin, a specific tubulin acetylation inducer, reduced insulin-stimulated glucose uptake and GLUT4 translocation. Conversely, decreasing α-tubulin K40 acetylation by expressing a nonacetylable dominant form of α-tubulin (mCherry α-tubulin K40A mutant) remarkably intensified insulin-induced glucose transport. Finally, mCherry α-tubulin K40A expression similarly improved glucose transport in insulin-resistant cardiomyocytes or after AMP-activated protein kinase activation. Taken together, our study demonstrates that modulation of α-tubulin K40 acetylation level affects glucose transport in cardiomyocytes, offering new putative therapeutic insights regarding modulation of glucose metabolism in insulin-resistant and diabetic hearts. Acetylation level of α-tubulin on K40 is increased in the heart of a diet-induced mouse model of type 2 diabetes. Pharmacological stimulation of α-tubulin K40 acetylation lowers insulin-mediated GLUT4 vesicles translocation to the plasma membrane, reducing glucose transport. Expressing a nonacetylable dominant form of α-tubulin boosts glucose uptake in both insulin-sensitive and insulin-resistant cardiomyocytes.

Heart failure, mostly associated with cardiac hypertrophy, is still a major cause of illness and death. Oxidative stress causes contractile failure and the accumulation of reactive oxygen species leads to mitochondrial dysfunction, associated with aging and heart failure, suggesting that mitochondria-targeted therapies could be effective in this context. The purpose of this work was to characterize how mitochondrial oxidative stress is involved in cardiac hypertrophy development and to determine if mitochondria-targeted therapies could improve cardiac phenotypes. We used neonatal and adult rat cardiomyocytes (NCMs and ACMs) hypertrophied by isoproterenol (Iso) to induce an increase of mitochondrial superoxide anion. Superoxide dismutase 2 activity and mitochondrial biogenesis were significantly decreased after 24h of Iso treatment. To counteract the mitochondrial oxidative stress induced by hypertrophy, we evaluated the impact of two different anti-oxidants, mitoquinone (MitoQ) and EUK 134. Both significantly decreased mitochondrial superoxide anion and hypertrophy in hypertrophied NCMs and ACMs. Conversely to EUK 134 which preserved cell functions, MitoQ impaired mitochondrial function by decreasing maximal mitochondrial respiration, mitochondrial membrane potential and mitophagy (particularly Parkin expression) and altering mitochondrial structure. The same decrease of Parkin was found in human cardiomyocytes but not in fibroblasts suggesting a cell specificity deleterious effect of MitoQ. Our data showed the importance of mitochondrial oxidative stress in the development of cardiomyocyte hypertrophy. Interestingly, we observed that targeting mitochondria by an anti-oxidant (MitoQ) impaired metabolism specifically in cardiomyocytes. Conversely, the SOD mimic (EUK 134) decreased both oxidative stress and cardiomyocyte hypertrophy and restored impaired cardiomyocyte metabolism and mitochondrial biogenesis.

International audience; Prediabetes is a strong predictor of type 2 diabetes and its associated cardiovascular complications, but few studies explore sexual dimorphism in this context. Here, we aim to determine whether sex influences physiological response to high-fat high-sucrose diet (HFS) and myocardial tolerance to ischemia-reperfusion injury. Male and female Wistar rats were subjected to standard (CTRL) or HFS diet for 5 months. Then, ex-vivo experiments on isolated perfused heart model were performed to evaluate tolerance to ischemia-reperfusion injury. HFS diet induced fasting hyperglycemia and increased body fat percent to a similar level in both sexes. However, glucose intolerance was more pronounced in female HFS. Cholesterol was increased only in female while male displayed higher level of plasmatic leptin. We observed increased heart weight to tibia length ratio only in males, but we showed a similar decrease in tolerance to ischemia-reperfusion injury in female and male HFS compared with respective controls, characterized by impaired cardiac function, energy metabolism and coronary flow during reperfusion. In conclusion, as soon as glucose intolerance and hyperglycemia develop, we observe higher sensitivity of hearts to ischemia-reperfusion injury without difference between males and females.

International audience; Type 2 diabetes is a chronic disease associated with micro- and macro-vascular complications, including myocardial ischemia, and also with a specific and intrinsic cardiac dysfunction called diabetic cardiomyopathy (DCM). Both clinical and animal studies demonstrate significant sex differences in prevalence, pathophysiology, and outcomes of cardiovascular diseases (CVDs), including those associated with diabetes. The increased risk of CVDs with diabetes is higher in women compared to men with 50% higher risk of coronary artery diseases and increased mortality when exposed to acute myocardial infarction. Clinical studies also reveal a sexual dimorphism in the incidence and outcomes of DCM. Based on these clinical findings, growing experimental research was initiated to understand the impact of sex on CVDs associated with diabetes and to identify the molecular mechanisms involved. Endothelial dysfunction, atherosclerosis, coagulation, and fibrosis are mechanisms found to be sex-differentially modulated in the diabetic cardiovascular system. Recently, impairment of energy metabolism also emerged as a determinant of multiple CVDs associated with diabetes. Therefore, future studies should thoroughly analyze the sex-specific metabolic determinants to propose new therapeutic targets. With current medicine tending toward more personalized care of patients, we finally propose to discuss the importance of sex as determinant in the treatment of diabetes-associated cardiac diseases to promote a more systemic inclusion of both males and females in clinical and preclinical studies.

Introduction Prediabetic women are at greater risk of cardiovascular diseases than men, investigating new sex dependent strategic therapies is then essential to limit cardiovascular complications in prediabetic women. Objective We aimed to evaluate the effects of resveratrol supplementation (RSV) or restauration of a standard diet on the heart of prediabetic female rats submitted to high-fat-high-sucrose diet (HFS). Methods Wistar female rats were divided in 4 groups fed for 5 months with: normal or HFS diet (CTRL/HFS), HFS with RSV (1 mg/kg/day) during the last 2 months or HFS for 3 months and 2 months of standard diet (RSD). We performed a longitudinal in vivo study of cardiac function, morphology and perfusion by MRI, then rats underwent an IPGTT. Ex vivo experiments on isolated perfused hearts were realized to study cardiac function [rate pressure product (RPP), end diastolic pressure (EDP)] and energy metabolism with 31P magnetic resonance spectroscopy during an ischemia-reperfusion injury (IR). Tissues were collected for analyzes. Results Five months of HFS diet-induced glucose intolerance (P Conclusion The two approaches have distinct effects on cardiac function and energy metabolism of prediabetic female rats. Further studies are on the go to explore the mechanisms involved.

OBJECTIVES: To investigate any gender effect of the beta-1 adrenergic blocker, landiolol, on cardiac performance and energy metabolism in septic rats, and to explore the expression of genes and proteins involved in this process. DESIGN: Randomized animal study. SETTING: University research laboratory. SUBJECTS: Male and female Wistar rats. INTERVENTIONS: One hour after cecal ligation and puncture, male and female rats were randomly allocated to the following groups: sham male, cecal ligation and puncture male, cecal ligation and puncture + landiolol male, sham female, cecal ligation and puncture female, and cecal ligation and puncture + landiolol female. Cardiac MRI was carried out 18 hours after cecal ligation and puncture to assess in vivo cardiac function. Ex vivo cardiac function measurement and P magnetic resonance spectroscopy were subsequently performed using an isovolumic isolated heart preparation. Finally, we assessed cardiac gene and protein expression. MEASUREMENTS AND MAIN RESULTS: In males, landiolol increased indexed stroke volume by reversing the indexed end-diastolic volume reduction without affecting left ventricle ejection fraction. In females, landiolol did not increase indexed stroke volume and indexed end-diastolic volume but decreased left ventricle ejection fraction. Landiolol had no effect on ex vivo cardiac function and on high-energy phosphate compounds. The effect of landiolol on the gene expression of natriuretic peptide receptor 3 and on protein expression of phosphorylated-AKT:AKT ratio and endothelial nitric oxide synthase was different in males and females. CONCLUSIONS: Landiolol improved the in vivo cardiac performance of septic male rats while deleterious effects were reported in females. Expression of natriuretic peptide receptor 3, phosphorylated-AKT:AKT, and endothelial nitric oxide synthase are signaling pathways to investigate to better understand the sex differences in sepsis.

Introduction Type 2 diabetic women are at greater risk of cardiovascular (CV) diseases than men, but the mechanisms involved are still poorly understood. Objective The objective of this study was to investigate the effect of sex on the myocardial tolerance to ischemia-reperfusion (IR) injury in type 2 diabetic Goto-Kakizaki (GK) rats. Method We performed ex vivo experiments on isolated perfused hearts to evaluate tolerance to IR injury of male and female GK and Wistar rats. We simultaneously measured energy metabolism by 31P magnetic resonance spectroscopy, myocardial function and coronary flow. At the end of the experiments, biochemical analyses were performed on plasma and hearts. Results GK rats had cardiac hypertrophy and higher glycemia than control rats, without effect of sex. Basal oxidative stress was significantly higher only in female GK rats in comparison to other groups, with higher plasmatic level of 8-iso-PGF2α. Male and female GK rats had impaired cardiac function before and after IR injury in comparison to respective controls. Interestingly, female GK rats had greater impairment of cardiac function than male GK during reperfusion, associated with decreased ATP and PCr level, and higher impairment of coronary flow. Biochemical analyses in hearts showed downward trend in SIRT1 expression in GK rats versus control groups, without sex-effect. Citrate synthase activity and SIRT3 protein expression were similar between groups. Conclusion These results indicate that sex influences the myocardial tolerance to IR injury in type 2 diabetes. Mitochondrial and endothelial dysfunction might explain why female GK have lower myocardial function during reperfusion. These results may be related to the higher risk of cardiovascular complications among type 2 diabetic women.

International audience; Prediabetes is an important risk factor for type 2 diabetes and cardiovascular complications, such as myocardial infarction. However, few studies explore female sexin this context. Here, we aim to investigate the effects of high-fat high-sucrose diet on cardiac parameters and sensitivity to ischemia-reperfusion injury of female Wistar rats.Female Wistar rats received for 5 months normal diet (CTRL group) or high-fat high-sucrose diet (HFS group). Every month MRI was performed to follow myocardial morphology, function and perfusion; cardiac and hepatic triglyceride content; and amount of sub-cutaneous and visceral adipose tissues.Then, ex vivoexperiments were performed on isolated perfused heartsto evaluate tolerance to ischemia-reperfusion, with simultaneous measurement of energy metabolism by 31P MRS and contractile function. Coronary flow was measured before and after ischemia.At the end of the experiments, hearts were freeze-clamped for biochemical assays. Five months of high-fat high-sucrose diet induced a prediabetic condition in female Wistar rats, associated with an increase in myocardial perfusion, systolic and diastolic wall thickness. HFS rats also exhibited higher sensitivity to ischemia-reperfusion injury in comparison to controls, characterized by impaired cardiac function, energy metabolism and endothelial function. Biochemical analyses in hearts highlighted eNOS uncoupling, higher malondialdehyde level and lower S-Glutathionylation of proteinsin HFS rats,indicating higher oxidative stress. Prediabetes induced by energy-densediet was associated with modification of cardiac morphology and higher myocardial sensitivity to ischemia-reperfusion injury. These results may be related to the high risk of cardiovascular complications among type 2diabetic women.

Introduction Type 2 diabetic women present high risk of mortality by cardiovascular (CV) disease in comparison to non-diabetic women. Most of anti-diabetic treatments do not decrease patient's CV mortality, therefore new approaches need to be found. Resveratrol (RSV) is a polyphenol found in grapes reported to be beneficial on oxidative stress, endothelial dysfunction and inflammation involved in CV complications of T2D. Objective We have investigated the effect of RSV on the tolerance to ischemia-reperfusion (IR) injury of type 2 diabetic female Goto-Kakizaki (GK) rat hearts. Methods Four groups were used: a control group, a GK group, a GK group with placebo and a GK group with RSV treatment at the dose of 1mg/kg/day in drinking water for 8 weeks. After 8 weeks of RSV treatment, tolerance to IR injury was assessed during ex vivo experiments, with simultaneous measurement of energy metabolism by 31P MRS, myocardial function and coronary flow. At the end of experiments, PCr, creatine, adenine nucleotides contents and citrate synthase activity were assessed in freeze-clamped hearts as well as nitric oxide and sirtuin pathways. Results Type 2 diabetic GK rats exhibited cardiac hypertrophy and lower myocardial tolerance to IR injury in comparison to controls. RSV attenuated cardiac hypertrophy and increased myocardial tolerance to IR injury by improving cardiac function, mitochondrial energetic and endothelial pathways. Interestingly, RSV increased ATP, PCr, creatine, total adenine nucleotide heart contents, citrate synthase activity, as well as eNOS, P-Akt and SIRT1 protein expressions in GK rat hearts. Conclusion RSV induced cardioprotection against IR injury in type 2 diabetic female rats. Thus, RSV presents high potential for preventing and treating CV complications of type 2 diabetic women.

International audience; Type 2 diabetic women have a high risk of mortality via myocardial infarction even with anti-diabetic treatments. Resveratrol (RSV) is a natural polyphenol, well-known for its antioxidant property, which has also shown interesting positive effects on mitochondrial function. Therefore, we aim to investigate the potential protective effect of 1 mg/kg/day of RSV on high energy compounds, during myocardial ischemia-reperfusion in type 2 diabetic female Goto-Kakizaki (GK) rats. For this purpose, we used P-31 magnetic resonance spectroscopy in isolated perfused heart experiments, with a simultaneous measurement of myocardial function and coronary flow. RSV enhanced adenosine triphosphate (ATP) and phosphocreatine (PCr) contents in type 2 diabetic hearts during reperfusion, in combination with better functional recovery. Complementary biochemical analyses showed that RSV increased creatine, total adenine nucleotide heart contents and citrate synthase activity, which could be involved in better mitochondrial functioning. Moreover, improved coronary flow during reperfusion by RSV was associated with increased eNOS, SIRT1, and P-Akt protein expression in GK rat hearts. In conclusion, RSV induced cardioprotection against ischemia-reperfusion injury in type 2 diabetic female rats via increased high energy compound contents and expression of protein involved in NO pathway. Thus, RSV presents high potential to protect the heart of type 2 diabetic women from myocardial infarction.

Introduction Metabolic syndrome can predict type 2 diabetes and cardiovascular complications, such as myocardial infarction. However, few studies explore gender differences in this context. Objective The aim of this study was to compare the effects of a high-fat-high-sucrose diet (HFHSD) on the sensitivity to ischemia-reperfusion injury of male and female Wistar rat hearts. Method Male and female Wistar rats were subjected to HFHSD or normal diet (ND) for 5 months. Then, rats underwent an intraperitoneal glucose tolerance test (IPGTT) to determine glycemic status, and ex vivo experiments on the isolated perfused heart were performed to study simultaneously cardiac function and energy metabolism with 31 P MRS during an ischemia-reperfusion injury. Finally, hearts were freeze-clamped for biochemical assays. Results After 5 months of HFHSD, body weight was increased in males ( P P P P P P P P P P P P Conclusion Despite gender differences in tolerance to glucose, body weight and heart weight to tibia length ratio, we found no effect of gender in tolerance to ischemia-reperfusion injury in our model of metabolic syndrome.

Background Cardiovascular complications of obesity and diabetes are major health problems. Assessing their development, their link with ectopic fat deposition and their flexibility with therapeutic intervention is essential. The aim of this study was to longitudinally investigate cardiac alterations and ectopic fat accumulation associated with diet-induced obesity using multimodal cardiovascular magnetic resonance (CMR) in mice. The second objective was to monitor cardiac response to exendin-4 (GLP-1 receptor agonist). Methods Male C57BL6R mice subjected to a high fat (35 %) high sucrose (34 %) (HFHSD) or a standard diet (SD) during 4 months were explored every month with multimodal CMR to determine hepatic and myocardial triglyceride content (HTGC, MTGC) using proton MR spectroscopy, cardiac function with cine cardiac MR (CMR) and myocardial perfusion with arterial spin labeling CMR. Furthermore, mice treated with exendin-4 (30 μg/kg SC BID) after 4 months of diet were explored before and 14 days post-treatment with multimodal CMR. Results HFHSD mice became significantly heavier (+33 %) and displayed glucose homeostasis impairment (1-month) as compared to SD mice, and developed early increase in HTGC (1 month, +59 %) and MTGC (2-month, +63 %). After 3 months, HFHSD mice developed cardiac dysfunction with significantly higher diastolic septum wall thickness (sWtnD) (1.28 ± 0.03 mm vs. 1.12 ± 0.03 mm) and lower cardiac index (0.45 ± 0.06 mL/min/g vs. 0.68 ± 0.07 mL/min/g, p = 0.02) compared to SD mice. A significantly lower cardiac perfusion was also observed (4 months:7.5 ± 0.8 mL/g/min vs. 10.0 ± 0.7 mL/g/min, p = 0.03). Cardiac function at 4 months was negatively correlated to both HTGC and MTGC (p < 0.05). 14-day treatment with Exendin-4 (Ex-4) dramatically reversed all these alterations in comparison with placebo-treated HFHSD. Ex-4 diminished myocardial triglyceride content (−57.8 ± 4.1 %), improved cardiac index (+38.9 ± 10.9 %) and restored myocardial perfusion (+52.8 ± 16.4 %) under isoflurane anesthesia. Interestingly, increased wall thickness and hepatic steatosis reductions were independent of weight loss and glycemia decrease in multivariate analysis (p < 0.05). Conclusion CMR longitudinal follow-up of cardiac consequences of obesity and diabetes showed early accumulation of ectopic fat in mice before the occurrence of microvascular and contractile dysfunction. This study also supports a cardioprotective effect of glucagon-like peptide-1 receptor agonist. Electronic supplementary material The online version of this article (doi:10.1186/s12968-015-0198-x) contains supplementary material, which is available to authorized users.