Prolonged-release pirfenidone prevents obesity-induced cardiac steatosis and fibrosis in a mouse NASH model.

PURPOSE: Obesity is associated with systemic insulin resistance and cardiac hypertrophy with fibrosis. Peroxisome proliferator-activated receptors (PPARs) regulate carbohydrate and lipid metabolism, improving insulin sensitivity, triglyceride levels, inflammation, and oxidative stress. We previously demonstrated that prolonged-release pirfenidone (PR-PFD) is an agonistic ligand for Pparα with anti-inflammatory and anti-fibrotic effects, and might be a promising drug for cardiac diseases-treatment. Here, we investigated the effects of PR-PFD in ventricular tissue of mice with nonalcoholic steatohepatitis (NASH) and obesity induced by high-fat/high-carbohydrate (HFHC) diet. METHODS: Five male C57BL/6 J mice were fed with normal diet (ND) and ten with HFHC diet for 16 weeks; at 8 weeks of feeding, five mice with HFHC diet were administered PR-PFD (350 mg/kg/day) mixed with HFHC diet. RESULT: Systemic insulin resistance, heart weight/body weight ratio, myocardial steatosis with inflammatory foci, hypertrophy, and fibrosis were prevented by PR-PFD. In addition, HFHC mice showed significantly increased desmin, Tgfß1, Timp1, collagen I (Col I), collagen III (Col III), TNF-α, and Nrf2 mRNA levels, including α-SMA, NF-kB, Nrf2, troponin I, Acox1, Cpt1A, and Lxrα protein levels compared with the ND ventricular tissues. Mechanistically, HFHC mice with PR-PFD treatment significantly decreased these genes overexpressed by HFHC diet. Furthermore, PR-PFD overexpressed the Pgc1a mRNA levels and Pparα, Pparγ, Acox1, and Cpt1A protein levels. CONCLUSIONS: The results suggest that PR-PFD could be a promising drug for the prevention and treatment of cardiac steatosis and fibrosis induced by obesity.

Cardiac overexpression of perilipin 2 induces atrial steatosis, connexin 43 remodeling, and atrial fibrillation in aged mice.

Atrial fibrillation (AF) is prevalent in patients with obesity and diabetes, and such patients often exhibit cardiac steatosis. Since the role of cardiac steatosis per se in the induction of AF has not been elucidated, the present study was designed to explore the relation between cardiac steatosis and AF. Transgenic (Tg) mice with cardiac-specific overexpression of perilipin 2 (PLIN2) were housed in the laboratory for more than 12 mo before the study. Electron microscopy of the atria of PLIN2-Tg mice showed accumulation of small lipid droplets around mitochondrial chains, and five- to ninefold greater atrial triacylglycerol (TAG) content compared with wild-type (WT) mice. Electrocardiography showed significantly longer RR intervals in PLIN2-Tg mice than in WT mice. Transesophageal electrical burst pacing resulted in significantly higher prevalence of sustained (>5 min) AF (69%) in PLIN2-Tg mice than in WT mice (24%), although it was comparable in younger (4-mo-old) mice. Connexin 43 (Cx43), a gap junction protein, was localized at the intercalated disks in WT atria but was heterogeneously distributed on the lateral side of cardiomyocytes in PLIN2-Tg atria. Langendorff-perfused hearts using the optical mapping technique showed slower and heterogeneous impulse propagation in PLIN2-Tg atria compared with WT atria. Cardiac overexpression of hormone-sensitive lipase in PLIN2-Tg mice resulted in atrial TAG depletion and amelioration of AF susceptibility. The results suggest that PLIN2-induced steatosis is associated with Cx43 remodeling, impaired conduction propagation, and higher incidence of AF in aged mice. Therapies targeting cardiac steatosis could be potentially beneficial against AF in patients with obesity or diabetes.

Metabolic syndrome associates with left atrial dysfunction.

BACKGROUND AND AIMS: Obesity and metabolic syndrome (MetS) are risk factors of atrial fibrillation (AF), but limited data exist on their effect on left atrial (LA) function. The aim of the study was to evaluate the effects of cardiac, hepatic and intra-abdominal ectopic fat depots and cardiometabolic risk factors on LA function in non-diabetic male subjects. METHODS AND RESULTS: Myocardial and hepatic triglyceride contents were measured with 1.5T 1H-magnetic resonance spectroscopy and LA and left ventricular function, visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), epicardial and pericardial fat by magnetic resonance imaging (MRI) in 33 men with MetS and 40 men without MetS. LA volumes were assessed using a novel three-chamber orientation based MRI approach. LA ejection fraction (EF) was lower in MetS patients than in the control group (44 ± 7.7% in MetS vs. 49 ± 8.6% in controls, p = 0.013) without LA enlargement, indicating LA dysfunction. LA EF correlated negatively with waist circumference, body mass index, SAT, VAT, fasting serum insulin, and homeostasis model assessment of insulin resistance index, and positively with fasting serum high-density lipoprotein cholesterol. VAT was the best predictor of reduced LA EF. CONCLUSIONS: MetS associates with subclinical LA dysfunction. Multiple components of MetS are related to LA dysfunction, notably visceral obesity and insulin resistance. Further studies are needed to elucidate the role of mechanical atrial remodeling in the development of AF.

Gliptin therapy reduces hepatic and myocardial fat in type 2 diabetic patients.

BACKGROUND: Increased hepatic fat and cardiac fat are common in patients with type 2 diabetes mellitus (T2DM) and are associated with a greater risk of liver fibrosis and cardiovascular (CV) events. Sex-specific differences of dipeptidyl peptidase-four (DPP-4) inhibitor effects on hepatic (HCL) and myocardial fat content (MYCL) have not yet been evaluated. METHOD: Forty-one T2DM patients (20 male, 21 female) received a gliptin add-on therapy if HbA1c goals were not reached under metformin monotherapy. They underwent cardiac and liver magnetic resonance tomography and spectroscopy before and 6 months after therapy initiation. Plasma samples were analysed for the growth differentiation factor 15 (GDF-15), a novel marker for cardiovascular risk. RESULTS: Thirty-eight patients on gliptin therapy completed the study. We observed a positive correlation between MYCL and HCL before therapy (R = 0·41, P = 0·05). After 6 months of therapy, we noticed a significant weight reduction in women only (P = 0·02) whereas waist circumference decreased similarly in both sexes. HbA1c sunk significantly in both sexes (P = 0·002). HCL decreased significantly (P = 0·0004), with women featuring higher basal HCL (P < 0·05). MYCL decreased in women only (P = 0·01) and GDF-15 comparably in both sexes (P < 0·05). CONCLUSIONS: 6 months of DPP-4-therapy led to a significant overall decrease in HCL and body weight such as a reduction of MYCL only in women. This preliminary data set could implicate that gliptin may be a feasible therapy option in fatty liver patients with diabetes potentially including positive effects on cardiovascular function particularly in women.

Chronic plus binge ethanol feeding induces myocardial oxidative stress, mitochondrial and cardiovascular dysfunction, and steatosis.

Alcoholic cardiomyopathy in humans develops in response to chronic excessive alcohol consumption; however, good models of alcohol-induced cardiomyopathy in mice are lacking. Herein we describe mouse models of alcoholic cardiomyopathies induced by chronic and binge ethanol (EtOH) feeding and characterize detailed hemodynamic alterations, mitochondrial function, and redox signaling in these models. Mice were fed a liquid diet containing 5% EtOH for 10, 20, and 40 days (d) combined with single or multiple EtOH binges (5 g/kg body wt). Isocalorically pair-fed mice served as controls. Left ventricular (LV) function and morphology were assessed by invasive pressure-volume conductance approach and by echocardiography. Mitochondrial complex (I, II, IV) activities, 3-nitrotyrosine (3-NT) levels, gene expression of markers of oxidative stress (gp91phox, p47phox), mitochondrial biogenesis (PGC1α, peroxisome proliferator-activated receptor α), and fibrosis were examined. Cardiac steatosis and fibrosis were investigated by histological/immunohistochemical methods. Chronic and binge EtOH feeding (already in 10 days EtOH plus single binge group) was characterized by contractile dysfunction (decreased slope of end-systolic pressure-volume relationship and preload recruitable stroke work), impaired relaxation (decreased time constant of LV pressure decay and maximal slope of systolic pressure decrement), and vascular dysfunction (impaired arterial elastance and lower total peripheral resistance). This was accompanied by enhanced myocardial oxidative/nitrative stress (3-NT; gp91phox; p47phox; angiotensin II receptor, type 1a) and deterioration of mitochondrial complex I, II, IV activities and mitochondrial biogenesis, excessive cardiac steatosis, and higher mortality. Collectively, chronic plus binge EtOH feeding in mice leads to alcohol-induced cardiomyopathies (National Institute on Alcohol Abuse and Alcoholism models) characterized by increased myocardial oxidative/nitrative stress, impaired mitochondrial function and biogenesis, and enhanced cardiac steatosis.

Obesity-induced cardiac lipid accumulation in adult mice is modulated by G protein-coupled receptor kinase 2 levels.

BACKGROUND: The leading cause of death among the obese population is heart failure and stroke prompted by structural and functional changes in the heart. The molecular mechanisms that underlie obesity-related cardiac remodeling are complex, and include hemodynamic and metabolic alterations that ultimately affect the functionality of the myocardium. G protein-coupled receptor kinase 2 (GRK2) is an ubiquitous kinase able to desensitize the active form of several G protein-coupled receptors (GPCR) and is known to play an important role in cardiac GPCR modulation. GRK2 has also been recently identified as a negative modulator of insulin signaling and systemic insulin resistance. METHODS: We investigated the effects elicited by GRK2 downregulation in obesity-related cardiac remodeling. For this aim, we used  9 month-old wild type (WT) and GRK2+/- mice, which display circa 50% lower levels of this kinase, fed with either a standard or a high fat diet (HFD) for 30 weeks. In these mice we studied different parameters related to cardiac growth and lipid accumulation. RESULTS: We find that GRK2+/- mice are protected from obesity-promoted cardiac and cardiomyocyte hypertrophy and fibrosis. Moreover, the marked intracellular lipid accumulation caused by a HFD in the heart is not observed in these mice. Interestingly, HFD significantly increases cardiac GRK2 levels in WT but not in GRK2+/- mice, suggesting that the beneficial phenotype observed in hemizygous animals correlates with the maintenance of GRK2 levels below a pathological threshold. Low GRK2 protein levels are able to keep the PKA/CREB pathway active and to prevent HFD-induced downregulation of key fatty acid metabolism modulators such as Peroxisome proliferator-activated receptor gamma co-activators (PGC1), thus preserving the expression of cardioprotective proteins such as mitochondrial fusion markers mitofusin MFN1 and OPA1. CONCLUSIONS: Our data further define the cellular processes and molecular mechanisms by which GRK2 down-regulation is cardioprotective during diet-induced obesity, reinforcing the protective effect of maintaining low levels of GRK2 under nutritional stress, and showing a role for this kinase in obesity-induced cardiac remodeling and steatosis.

Suppression of plasma free fatty acids reduces myocardial lipid content and systolic function in type 2 diabetes.

BACKGROUND AND AIM: Type 2 diabetes (T2DM) is closely associated with the development of heart failure, which might be related with impaired substrate metabolism and accumulation of myocardial lipids (MYCL). The aim of this study was to investigate the impact of an acute pharmacological inhibition of adipose tissue lipolysis leading to reduced availability of circulating FFA on MYCL and heart function in T2DM. METHODS AND RESULTS: 8 patients with T2DM (Age: 56 ± 11; BMI: 28 ± 3.5 kg/m(2); HbA1c: 7.29 ± 0.88%) were investigated on two study days in random order. Following administration of Acipimox or Placebo MYCL and heart function were measured by (1)H-magnetic-resonance-spectroscopy and tomography at baseline, at 2 and at 6 h. Acipimox reduced circulating FFA by -69% (p < 0.001), MYCL by -39 ± 41% (p < 0.001) as well as systolic heart function (Ejection Fraction (EF): -13 ± 8%, p = 0.025; Cardiac Index: -16 ± 15%, p = 0.063 compared to baseline). Changes in plasma FFA concentrations strongly correlated with changes in MYCL (r = 0.707; p = 0.002) and EF (r = 0.651; p = 0.006). Diastolic heart function remained unchanged. CONCLUSIONS: Our results indicate, that inhibition of adipose tissue lipolysis is associated with a rapid depletion of MYCL-stores and reduced systolic heart function in T2DM. These changes were comparable to those previously found in insulin sensitive controls. MYCL thus likely serve as a readily available energy source to cope with short-time changes in FFA availability.

Electrocardiographic changes associated with insulin resistance.

BACKGROUND AND AIM: Cardiac steatosis has been related to increased risk of heart disease. We investigated the association between cardiac steatosis, electrocardiographic (ECG) abnormalities, and individual components of the metabolic syndrome (MetS). METHODS AND RESULTS: A 12-lead ECG and laboratory data were examined in 31 men with the MetS and in 38 men without the MetS. Myocardial triglyceride (MTG) content was measured with 1.5 T magnetic resonance (MR) spectroscopy and epicardial and pericardial fat by MR imaging. MTG content, epicardial and pericardial fat depots were higher in men with the MetS compared with subjects without the MetS (p < 0.001). The heart rate was increased (p < 0.001), the PR interval was longer (p < 0.044), the frontal plane QRS axis shifted to the left (p < 0.001), and the QRS voltage (p < 0.001) was lower in subjects with the MetS. The frontal plane QRS axis and the QRS voltage were inversely correlated with MTG content, waist circumference (WC), body mass index (BMI), TGs, and fasting blood glucose. High-density lipoprotein cholesterol correlated positively and measures of insulin resistance negatively with the QRS voltage. MTG content and hypertriglyceridemia were determinants of the frontal plane QRS and WC and hyperglycemia were predictors of the QRS voltage. CONCLUSION: The MetS and cardiac steatosis appear to associate with multiple changes on 12-lead ECG. The frontal plane QRS axis is shifted to the left and the QRS voltage is lower in subjects with the MetS. Standard ECG criteria may underestimate the presence of left ventricular hypertrophy in obese subjects with cardiometabolic risk factors.

Ectopic lipid metabolism in anterior pituitary dysfunction.

Over the past decades, adapted lifestyle and dietary habits in industrialized countries have led to a progress of obesity and associated metabolic disorders. Concomitant insulin resistance and derangements in lipid metabolism foster the deposition of excess lipids in organs and tissues with limited capacity of physiologic lipid storage. In organs pivotal for systemic metabolic homeostasis, this ectopic lipid content disturbs metabolic action, thereby promotes the progression of metabolic disease, and inherits a risk for cardiometabolic complications. Pituitary hormone syndromes are commonly associated with metabolic diseases. However, the impact on subcutaneous, visceral, and ectopic fat stores between disorders and their underlying hormonal axes is rather different, and the underlying pathophysiological pathways remain largely unknown. Pituitary disorders might influence ectopic lipid deposition indirectly by modulating lipid metabolism and insulin sensitivity, but also directly by organ specific hormonal effects on energy metabolism. In this review, we aim to I) provide information about the impact of pituitary disorders on ectopic fat stores, II) and to present up-to-date knowledge on potential pathophysiological mechanisms of hormone action in ectopic lipid metabolism.

Lipid inclusions in cardiac myocytes - a rare case of cardiolipotoxicity.

The heart oxidizes fatty acids for its energy production. The physiological balance between fatty acid uptake and its oxidation prevents lipid accumulation in cardiac myocytes. However, accumulation of lipids due to various processes such as obesity, diabetes, heart failure, myocardial ischemia or infarction can result in damage to the heart tissue, also known as cardiolipotoxicity. We present a unique case of a 69-year-old gentleman with a history of heart failure and ventricular tachycardia. Endomyocardial biopsy to assess for restrictive cardiomyopathy/amyloid showed no evidence of amyloid, significant inflammation or fibrosis, but did show intracellular accumulation of significant amorphous material in most cardiac myocytes. We review the literature regarding the pathogenesis of cardiolipotoxicity, which has no definite cause or treatment yet identified.

Epicardial and Pericardial Adiposity Without Myocardial Steatosis in Cushing Syndrome.

CONTEXT: Cardiovascular disease is the leading cause of death in patients with Cushing syndrome. Cortisol excess and adverse metabolic profile could increase cardiac fat, which can subsequently impair cardiac structure and function. OBJECTIVE: We aimed to evaluate cardiac fat mass and distribution in patients with Cushing syndrome. METHODS: In this prospective, cross-sectional study, 23 patients with Cushing syndrome and 27 control individuals of comparable age, sex, and body mass index were investigated by cardiac magnetic resonance imaging and proton spectroscopy. Patients were explored before and after biochemical disease remission. Myocardial fat measured by the Dixon method was the main outcome measure. The intramyocardial triglyceride/water ratio measured by spectroscopy and epicardial and pericardial fat volumes were secondary outcome measures. RESULTS: No difference was found between patients and controls in intramyocardial lipid content. Epicardial fat mass was increased in patients compared to controls (30.8 g/m2 [20.4-34.8] vs 17.2 g/m2 [13.1-23.5], P < .001). Similarly, pericardial fat mass was increased in patients compared to controls (28.3 g/m2 [17.9-38.0] vs 11.4 g/m2 [7.5-19.4], P = .003). Sex, glycated hemoglobin A1c, and the presence of hypercortisolism were independent determinants of epicardial fat. Pericardial fat was associated with sex, impaired glucose homeostasis and left ventricular wall thickness. Disease remission decreased epicardial fat mass without affecting pericardial fat. CONCLUSION: Intramyocardial fat stores are not increased in patients with Cushing syndrome, despite highly prevalent metabolic syndrome, suggesting increased cortisol-mediated lipid consumption. Cushing syndrome is associated with marked accumulation of epicardial and pericardial fat. Epicardial adiposity may exert paracrine proinflammatory effects promoting cardiomyopathy.

Plasma glucose, triglycerides, VLDL, leptin and resistin levels as potential biomarkers for myocardial fat in mice. / Niveles plasmáticos de glucosa, triglicéridos, VLDL, leptina y resistina como potenciales biomarcadores de la grasa miocárdica en ratones.

INTRODUCTION: The increase in myocardial fat has been proposed as one of the main precursors of myocardial dysfunction due to diabetic aetiology, independently of coronary artery disease. However, biomarkers reflecting the myocardial fat content for the clinical detection of this pathology are currently lacking. METHODS: Correlations between cardiac triglyceride content and plasma levels of major altered molecules during diabetes and cardiac mRNA levels of genes involved in cardiac metabolism (Cd36 and Pdk4) have been explored in a murine model of insulin resistance induced by a high-fat diet. RESULTS: In insulin-resistant mice, the fatty diet increased myocardial triglyceride levels, compared to control animals fed with a standard diet. The content of cardiac triglycerides was directly associated with plasma levels of glucose, triglycerides, VLDL, resistin and leptin. In addition, an inverse correlation was observed between the content of cardiac triglycerides and the cardiac mRNA levels of Cd36 and Pdk4. CONCLUSIONS: Our data reveal that the cardiac triglyceride content is associated with altered plasma biochemical profile and reprogramming of gene expression aimed to mitigate the impact of ectopic lipid accumulation in the myocardium.

Cardiac Steatosis in HIV-A Marker or Mediator of Disease?

Although people living with HIV (PLHIV) are approaching normal life expectancy, a limitation to achieving this goal is managing the higher prevalence of co-morbidities, including cardiovascular disease. Whilst ischaemic heart disease likely contributes to a large proportion of cardiac disease in the modern era of treatment, cardio-metabolic disease, including cardiac steatosis, akin to obesity-related heart disease, is also a possible mechanism of increased cardiac morbidity and mortality. HIV and other metabolic and inflammatory diseases affecting the heart, including obesity, share many cardio-metabolic abnormalities, with increased pericardial and myocardial fat content, in association with chronic systemic inflammatory changes and alterations in cardiac metabolism. Understanding the mechanisms of HIV-associated cardiac steatosis remains an important challenge, as managing the untreated metabolic and inflammatory precipitants may substantially improve cardiac outcomes for PLHIV.

Endothelial Lipase Is an Alternative Pathway for Fatty Acid Release from Lipoproteins: Evidence from a High Fat Diet Model of Obesity in Rats.

Lipoprotein lipase (LPL) and endothelial lipase (EL) are involved in lipoprotein metabolism. In insulin-resistance, their behavior is altered. Peroxisome proliferator-activated receptors (PPAR) and apoproteins (apo)CII and CIII could be partly responsible for these alterations. To evaluate this response, we assessed Lpl and Lipg expression, protein levels, and enzyme activity in adipose tissue (AT) and heart in an obesity model. Besides, we assessed the role of PPAR and apoC. Male Wistar rats were fed with standard diet (Control, n = 14) or high-fat diet (HFD, n = 14) for 14 weeks. Glucose and lipoprotein profiles were measured. Histological studies were performed in heart and epididymal AT. Lpl and Lipg were assessed by reverse transcription polymerase chain reaction (RT-qPCR), protein levels by Western Blot, and activities by radiometric assays. Cardiac and AT PPAR expression were measured by Western Blot and hepatic Apoc2 and Apoc3 mRNA by RT-qPCR. In HFD, fat deposits were observed in hearts, whereas AT presented a higher adipocyte size. In heart and AT, no differences were found in Lipg mRNA between groups, while AT Lpl mRNA and LPL protein were decreased in HFD, without differences in heart. In both tissues, EL protein levels and activity were increased and inversely associated with decreased LPL activity, being partially responsible for the atherogenic lipoprotein profile in HFD. PPARγ expression in AT was decreased in HFD, without differences in cardiac PPARδ expression and hepatic apoC mRNA. The increase in EL activity could be an alternative pathway for fatty acid release from lipoproteins and uptake in tissues with decreased LPL activity. In AT, PPARγ could be involved in enzyme regulation.

Heart, lipids and hormones.

Cardiovascular disease is the leading cause of death in general population. Besides well-known risk factors such as hypertension, impaired glucose tolerance and dyslipidemia, growing evidence suggests that hormonal changes in various endocrine diseases also impact the cardiac morphology and function. Recent studies highlight the importance of ectopic intracellular myocardial and pericardial lipid deposition, since even slight changes of these fat depots are associated with alterations in cardiac performance. In this review, we overview the effects of hormones, including insulin, thyroid hormones, growth hormone and cortisol, on heart function, focusing on their impact on myocardial lipid metabolism, cardiac substrate utilization and ectopic lipid deposition, in order to highlight the important role of even subtle hormonal changes for heart function in various endocrine and metabolic diseases.

Amplification of lipotoxic cardiomyopathy in the VDR gene knockout mouse.

Previous studies demonstrated that the liganded vitamin D receptor (VDR) plays an important role in controlling cardiovascular homeostasis. Both the whole animal VDR gene knockout (VDR-/-) and the myocyte-specific VDR gene deletion result in changes in cardiac structure and function. Clinical states associated with cardiac steatosis (obesity and diabetes mellitus) are also associated with low circulating 25 OH vitamin D levels. We, therefore, examined the effects of VDR deficiency (VDR-/- mouse) in a murine model of cardiac steatosis that expresses the terminal enzyme involved in triglyceride synthesis, diacylglycerol acyltransferase 1 (DGAT1), selectively in the cardiac myocyte. These mice display early cardiac dysfunction and late cardiomyopathy and heart failure. In the present study, we demonstrate that mice harboring both genetic modifications (i.e., MHC-DGAT1 Tg and VDR-/-) exhibit an increase in myocyte size, heart weight/body weight ratio and natriuretic peptide gene expression, all markers of cardiac hypertrophy, that exceed that seen in either VDR-/- or the MHC-DGAT1 Tg mice alone. This was accompanied by a dramatic increase in interstitial fibrosis and increased expression of collagen 1a1 and collagen 3a1, as well as the osteopontin and matrix metalloproteinase 2, genes. At a functional level, this resulted in a 37% reduction in ejection fraction and 55% reduction in fractional shortening in the DGAT1; VDR-/- mice relative to the controls. Collectively, these data demonstrate that deficiency in the vitamin D signaling system enhances the pathological phenotype in this experimental cardiomyopathy and suggest an important role for vitamin D in modulating disease severity in common cardiovascular disorders.

GLP-1 analog liraglutide protects against cardiac steatosis, oxidative stress and apoptosis in streptozotocin-induced diabetic rats.

OBJECTIVE: Accumulating evidence has implicated that GLP-1 may have a beneficial effect on cardiovascular but the mechanism is not fully understood. Here we show that GLP-1 analog, liraglutide, inhibits cardiac steatosis, oxidative stress and apoptosis in streptozotocin (STZ)-induced type 1 diabetic rats, via activation of AMPK-Sirt1 pathway. METHODS: Diabetic rats were treated with subcutaneous injections of liraglutide (0.3 mg/kg/12 h) for 4 weeks. Myocardial steatosis (detected by oil red O staining and myocardial triglyceride and diacylglycerol (DAG) contents assay), expression of protein kinase C (PKC), heart NAD(P)H oxidase activity, oxidative stress markers (8-hydroxy-2'-deoxyguanosine staining), apoptosis (TUNEL analysis) and genes that affect apoptosis and lipid metabolism were evaluated. RESULTS: Administration of liraglutide did not affect plasma glucose and insulin levels or body weights in STZ-induced diabetic rats, but normalized myocardial steatosis, expression of PKC, NAD(P)H oxidase activity, oxidative stress markers and apoptosis, all of which were significantly increased in diabetic hearts. Additionally, expression of genes mediating lipid uptake, synthesis and oxidation were increased in the diabetic hearts, and these increases were all reduced by liraglutide. In addition, liraglutide increased expression of Sirt1 and phosphorylated AMPK in the diabetic hearts. CONCLUSIONS: Liraglutide may have a beneficial effect on cardiac steatosis, DAG-PKC-NAD(P)H pathway, oxidative stress and apoptosis via activation of AMPK-Sirt1 pathway, independently of a glucose-lowering effect.

Myocardial steatosis and its association with obesity and regional ventricular dysfunction: evaluated by magnetic resonance tagging and 1H spectroscopy in healthy African Americans.

BACKGROUND: Cardiac steatosis is common in patients with diabetes or obesity, and cardiac steatosis may result in cardiomyopathy. However, factors associated with cardiac steatosis have not been reported in healthy individuals without diabetes and hypertension. The objectives of this study were to explore factors associated with myocardial triglyceride levels, and to examine the association between myocardial triglyceride and regional left ventricular (LV) function in healthy African Americans (AAs). METHODS: Between November 2010 and June 2012, 92 healthy AAs aged 21 years or older, without clinical evidence of cardiac dysfunction, coronary artery disease, diabetes, or hypertension from Baltimore, Maryland, were enrolled in an observational proton magnetic resonance spectroscopy and imaging study investigating factors associated with cardiac steatosis, and the relationships between cardiac steatosis and LV volumes and LV function. RESULTS: Among the participants, all had a low Framingham risk; 31 had a normal BMI, 23 were overweight and 38 were obese. The median myocardial triglyceride content was 0.5% (IQR: 0.3-1.0%). Among the factors investigated, BMI (R2=0.43, p=<0.0001) was independently associated with myocardial triglyceride. Overall, myocardial triglyceride was not associated with LV EF/structure, but may be associated with regional LV function. CONCLUSIONS: In healthy AA adults, obesity is associated with cardiac steatosis. In contrast to studies in patients with diabetes suggesting a link between cardiac steatosis and LV dysfunction, this study found no relationship between cardiac steatosis and left ventricular volumes or EF, though there is some evidence suggesting that cardiac steatosis may be associated with LV regional function in healthy AA women.