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Abstract Background Adipokines in serum derive mainly from subcutaneous and visceral adipose tissues. Epicardial adipose tissue (EAT), being a relatively small but unique fat depot, probably does not make an important contribution to systemic concentrations of adipokines. However, proximity of EAT to cardiac muscle and coronary arteries allows cells and proteins to penetrate between tissues. It is hypothesized that overexpression of proinflammatory cytokines in EAT plays an important role in pathophysiology of the heart. The aim of the study was to analyze the relationship between echocardiographic heart parameters and adipokines in plasma, epicardial, and subcutaneous fat in patients with obesity and type 2 diabetes mellitus (T2DM). Additionally, we evaluate proinflammatory properties of EAT by comparing that depot with subcutaneous adipose tissue. Methods The study included 55 male individuals diagnosed with coronary artery disease (CAD) who underwent planned coronary artery bypass graft. Plasma concentrations of leptin, adiponectin, resistin, visfatin, apelin, IL-6, and TNF-α, as well as their mRNA and protein expressions in EAT and subcutaneous adipose tissue (SAT) were determined. Results Obesity and diabetes were associated with increased leptin and decreased adiponectin plasma levels, higher protein expression of leptin and IL-6 in SAT, and higher visfatin protein expression in EAT. Impaired left ventricular (LV) diastolic function was associated with increased plasma concentrations of leptin, resistin, IL-6, and adiponectin, as well as with increased expressions of resistin, apelin, and adiponectin in SAT, and leptin in EAT. Conclusions Obesity and T2DM in individuals with CAD have a limited effect on adipokines. Expression of adipokines in EAT and SAT is linked to certain heart parameters, however diastolic dysfunction of the LV is strongly associated with circulating adipokines.

Abstract We sought to determine whether metformin treatment reverses a high-fat diet (HFD)-induced hepatic insulin resistance (IRes) and to identify lipid intermediates involved in induction of liver IRes. The experiments were conducted on male Wistar rats divided into three groups: 1. Control, 2. fed HFD and 3. fed HFD and treated with metformin. The animals were infused with a [U-13C]palmitate to measure fractional lipid synthesis rate. This allowed for the calculation of fractional synthesis rate of signaling lipids (FSR) through the estimation of their isotopic enrichment. Liver ceramide (Cer), diacylglycerol (DAG) and acyl-carnitine concentration and enrichment were analyzed by LC/MS/MS. The content of proteins involved in lipid metabolism and insulin signaling were analyzed by Western Blot. HFD treatment increased the content and FSR of DAG and Cer in the liver which was accompanied by systemic insulin resistance and inhibition of hepatic insulin signaling pathway under insulin stimulation. Metformin treatment ameliorated systemic insulin resistance and augmented the hepatic insulin signaling cascade. It reduced both the concentration and FSR of Cer, DAG, and increased acyl-carnitine content and the expression of mitochondrial markers. We postulate, that in liver, the insulin sensitizing effect of metformin depends on augmentation of mitochondrial β-oxidation, which protects from hepatic accumulation of both the Cer and DAG and preserves insulin sensitivity under HFD consumption. Moreover, we showed that hepatic content of Cer and DAG corresponds with their respective FSR.

The diaphragm is a dome-shaped skeletal muscle indispensable for breathing. Its activity contributes up to 70% of the total ventilatory function at rest. In comparison to other skeletal muscles, it is distinguished by an oxidative phenotype and uninterrupted cyclic contraction pattern. Surprisingly, the research regarding diaphragm diabetic phenotype particularly in the light of lipid-induced insulin resistance is virtually nonexistent. Male Wistar rats were randomly allocated into 3 groups: control, streptozotocin-induced (STZ) type-1 diabetes, and rodents fed with high-fat diet (HFD). Additionally, half of the animals from each group were administered with myriocin, a robust, selective inhibitor of ceramide synthesis and, therefore, a potent agent ameliorating insulin resistance. Diaphragm lipid contents were evaluated using chromatography. Fatty acid transporter expression was determined by Western blot. The STZ and HFD rats had increased concentration of lipids, namely, ceramides (CER) and diacylglycerols (DAG). Interestingly, this coincided with an increased concentration of long-chain (C ≥ 16) saturated fatty acid species present in both the aforementioned lipid fractions. The CER/DAG accumulation was accompanied by an elevated fatty acid transporter expression (FATP-1 in HFD and FATP-4 in STZ). Surprisingly, we observed a significantly decreased triacylglycerol content in the diaphragms of STZ-treated rats.

Myostatin (growth differentiation factor 8) is a member of the transforming growth factor-β superfamily. It is secreted mostly by skeletal muscles, although small amounts of myostatin are produced by the myocardium and the adipose tissue as well. Myostatin binds to activin IIB membrane receptors to activate the downstream intracellular canonical Smad2/Smad3 pathway, and additionally acts on non-Smad (non-canonical) pathways. Studies on transgenic animals have shown that overexpression of myostatin reduces the heart mass, whereas removal of myostatin has an opposite effect. In this review, we summarize the potential diagnostic and prognostic value of this protein in heart-related conditions. First, in myostatin-null mice the left ventricular internal diameters along with the diastolic and systolic volumes are larger than the respective values in wild-type mice. Myostatin is potentially secreted as part of a negative feedback loop that reduces the effects of the release of growth-promoting factors and energy reprogramming in response to hypertrophic stimuli. On the other hand, both human and animal data indicate that myostatin is involved in the development of the cardiac cachexia and heart fibrosis in the course of chronic heart failure. The understanding of the role of myostatin in such conditions might initiate a development of targeted therapies based on myostatin signaling inhibition.

Endothelial (EL) and lipoprotein (LPL) lipases are enzymes involved in lipoproteins metabolism and formation of atherosclerosis, a pathological feature of coronary artery disease (CAD). This paper examines the role of the lipases in the right atrial appendage (RAA) and coronary perivascular adipose tissue (PVAT) of patients with CAD alone or with accompanying diabetes. Additionally, correlation analysis for plasma concentration of the lipases, apolipoproteins (ApoA-ApoJ) and blood lipids (Chol, HDL-C, LDL-C, TAG) was performed. We observed that CAD had little effect on the lipases gene/protein levels in the RAA, while their transcript content was elevated in the PVAT of diabetic CAD patients. Interestingly, the RAA was characterized by higher expression of EL/LPL (EL: +1-fold for mRNA, +5-fold for protein; LPL: +2.8-fold for mRNA, +12-fold for protein) compared to PVAT. Furthermore, ApoA1 plasma concentration was decreased, whereas ApoC1 and ApoH were increased in the patients with CAD and/or diabetes. The concentrations of ApoC3 and ApoD were strongly positively correlated with TAG content in the blood, and the same was true for ApoB with respect to LDL-C and total cholesterol. Although plasma concentrations of EL/LPL were elevated in the patients with diabetes, CAD alone had little effect on blood, myocardial and perivascular fat expression of the lipases.

Muscle fatigue is defined as a decrease in maximal force or power generated in response to contractile activity, and it is a risk factor for the development of musculoskeletal injuries. One of the many stressors imposed on skeletal muscle through exercise is the increased production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), which intensifies as a function of exercise intensity and duration. Exposure to ROS/RNS can affect Na+/K+-ATPase activity, intramyofibrillar calcium turnover and sensitivity, and actin–myosin kinetics to reduce muscle force production. On the other hand, low ROS/RNS concentrations can likely upregulate an array of cellular adaptative responses related to mitochondrial biogenesis, glucose transport and muscle hypertrophy. Consequently, growing evidence suggests that exogenous antioxidant supplementation might hamper exercise-engendering upregulation in the signaling pathways of mitogen-activated protein kinases (MAPKs), peroxisome-proliferator activated co-activator 1α (PGC-1α), or mammalian target of rapamycin (mTOR). Ultimately, both high (exercise-induced) and low (antioxidant intervention) ROS concentrations can trigger beneficial responses as long as they do not override the threshold range for redox balance. The mechanisms underlying the two faces of ROS/RNS in exercise, as well as the role of antioxidants in muscle fatigue, are presented in detail in this review.

Endothelial lipase (EL) is an enzyme capable of HDL phospholipids hydrolysis. Its action leads to a reduction in the serum high-density lipoprotein concentration, and thus, it exerts a pro-atherogenic effect. This study examines the impact of a single bout exercise on the gene and protein expression of the EL in skeletal muscles composed of different fiber types (the soleus—mainly type I, the red gastrocnemius—mostly IIA, and the white gastrocnemius—predominantly IIX fibers), as well as the diaphragm, and the heart. Wistar rats were subjected to a treadmill run: (1) t = 30 [min], V = 18 [m/min]; (2) t = 30 [min], V = 28 [m/min]; (3) t = 120 [min], V = 18 [m/min] (designated: M30, F30, and M120, respectively). We established EL expression in the total muscle homogenates in sedentary animals. Resting values could be ordered with the decreasing EL protein expression as follows: endothelium of left ventricle > diaphragm > red gastrocnemius > right ventricle > soleus > white gastrocnemius. Furthermore, we observed that even a single bout of exercise was capable of inducing changes in the mRNA and protein level of EL, with a clearer pattern observed for the former. After 30 min of running at either exercise intensity, the expression of EL transcript in all the cardiovascular components of muscles tested, except the soleus, was reduced in comparison to the respective sedentary control. The protein content of EL varied with the intensity and/or duration of the run in the studied whole tissue homogenates. The observed differences between EL expression in vascular beds of muscles may indicate the muscle-specific role of the lipase.

Internal sensations, especially organic ones, are not only the foundation of our consciousness of life and self but also an integral part of each feeling. This is probably the origin of the genuine affinity between feelings and consciousness of life and self, an affinity that manifests itself even in speech. Indeed, the expression “sense of self” is more natural than saying “representing” or even “imagining one’s self”. It is also easier and neater to talk in French about “sentiment du moi” than “representation du moi”; the expression “das Ichgefühl” is less grating than “die Ichvorstellung”, the latter being rather used to mean the conceived self as opposed to the self of which one is conscious all the time. The self is not a feeling, however, if only because there are no feelings that would be equally constant or, to be more precise, that would recur with equal constancy. Even so, we can say it is closer to emotive states than to any representation or mental image. […]

Here we report the results of a three-year replicated field trial on the effects of novel clover- and alfalfa-based fertilizer products (Ekofert® K and Ekofert® L), with the input levels equivalent to 120, 180, or 240 kg N ha−1, on the yield and selected sensory and nutritional quality parameters of onion. The study showed that Ekofert fertilizer applied at all three levels produced similar or higher yields than the standard fertilization regimes used in conventional farming in all three seasons. Significant differences in onion composition profiles between fertilization treatments were detected within individual seasons; however, due to substantial interseasonal variation, no consistent differences could be detected between (i) mineral N and Ekofert fertilizer treatments, (ii) the two different Ekofert products, and (iii) contrasting Ekofert input levels. Results demonstrate that clover- and alfalfa-based pelleted organic fertilizer products are a suitable alternative for intensive organic field vegetable production.

Background/Aims: Liver X receptors (LXRα and LXRβ) are ligand-activated transcription factors that regulate expression of genes involved in lipid and cholesterol metabolism. LXR expression has been identified in the heart, and enhanced LXR activity in the streptozotocin (STZ) diabetic myocardium was reported recently. The aim of this study was to investigate effect of in vivo LXR activation on myocardial lipid metabolism under conditions of STZ-induced diabetes. Methods: Wistar rats were randomly divided into three experimental groups: non-diabetic control, treated with STZ, and treated with STZ and LXR agonist - TO901317. Diabetes was induced by a single intraperitonal injection of STZ at a dose of 55 mg/kg. LXR agonist was administrated once daily in the morning by an oral gavage at a dose of 10 mg/kg/d during the last week of the experiment. After anesthesia samples of blood and the left ventricle were taken. Results: TO901317 administration increased expression of both LXR isoforms and its target genes: sterol response element binding protein 1c (SREBP-1c) and acetyl-coenzyme A carboxylase 1 (ACC1) in the heart of streptozotocin-diabetic rats. Treatment with LXR agonist had no effect on plasma lipids and glucose in the diabetic rats. Concomitantly, content of the examined lipid classes in the diabetic heart (nonesterified fatty acids, triacylglycerols, phospholipids, cholesterol esters, ceramide) was unchanged after treatment with TO901317. On the contrary, myocardial level of cholesterol and diacylglycerols (DAG) was decreased after LXR activation in diabetic rats, the change in DAG level was associated with downregulated expression of adipose triglyceride lipase (ATGL). Conclusion: Activation of LXRs by TO901317 protects cardiomyocytes against DAG accumulation and thus may reverse disturbances in lipid metabolism observed in streptozotocin-diabetic heart.

The aim of our study was to examine the regulation of triacylglycerols (TG) metabolism in myocardium and heart perivascular adipose tissue in coronary atherosclerosis. Adipose triglyceride lipase (ATGL) is the major TG-hydrolase. The enzyme is activated by a protein called comparative gene identification 58 (CGI-58) and inhibited by a protein called G0/G1 switch protein 2 (G0S2). Samples of the right atrial appendage and perivascular adipose tissue were obtained from two groups of patients: 1—with multivessel coronary artery disease qualified for coronary artery bypass grafting (CAD), 2—patients with no atherosclerosis qualified for a valve replacement (NCAD). The mRNA and protein analysis of ATGL, HSL, CGI-58, G0S2, FABP4, FAT/CD36, LPL, β-HAD, CS, COX4/1, FAS, SREBP-1c, GPAT1, COX-2, 15-LO, and NFκβ were determined by using real-time PCR and Western Blot. The level of lipids (i.e., TG, diacylglycerol (DG), and FFA) was examined by GLC. We demonstrated that in myocardium coronary atherosclerosis increases only the transcript level of G0S2 and FABP4. Most importantly, ATGL, β-HAD, and COX4/1 protein expression was reduced and it was accompanied by over double the elevation in TG content in the CAD group. The fatty acid synthesis and their cellular uptake were stable in the myocardium of patients with CAD. Additionally, the expression of proteins contributing to inflammation was increased in the myocardium of patients with coronary stenosis. Finally, in the perivascular adipose tissue, the mRNA of G0S2 was elevated, whereas the protein content of FABP-4 was increased and for COX4/1 diminished. These data suggest that a reduction in ATGL protein expression leads to myocardial steatosis in patients with CAD.

Background/Aims: It is well documented that increased fatty acids (FA) supply causes lipid accumulation and insulin resistance in skeletal muscles. Whether the same mechanism is present in the heart is still unclear. Therefore, the goal of our study was to determine the content of specific myocardial lipid fractions during feeding rats a high fat diet (HFD) for 5 weeks. Moreover, the relation between changes in myocardial lipid content, whole body insulin resistance and the expression of fatty acid transporters in each week of HFD was established. Methods: Gas liquid chromatography and high performance liquid chromatography were used to determine the content of lipid fractions in the left ventricle. Expression of selected proteins was estimated by Western blot technique. All measurements were made after each week of HFD. Results: As expected, lipid profile in myocardium was altered by HFD in different weeks of the study with the most intense changes in triacylglycerols, long chain fatty acid-CoA and ceramide. Furthermore, there was a significant elevation of plasmalemmal (the 4th and the 5th week) and mitochondrial expression (from the 3rd to the 5th week) of fatty acid translocase. Conclusion: High fat diet affects myocardial lipid profile in each week of its duration and causes alternations in FA metabolism in cardiomyocytes.

Background/Aims: PGC-1α is an important cellular protein (coactivator) regulating myocyte mitochondria number and function, and therefore whole cellular energy status. The aim of this work was to investigate the effects of modest, temporary PGC-1α knock-down on L6 myotubes insulin resistance in a light of cellular lipid metabolism. Methods: Gas liquid chromatography was applied for assessing FAs content and composition. For the expression of mitochondrial enzymes, as well as FA and glucose transporters, Western Blot technique was adopted. Additionally, radiolabelled glucose and palmitic acid uptake was performed to estimate the nutrients cellular influx. Results: Modest (-24%) PGC-1α protein ablation resulted in decreased mitochondrial activity in general (reduced Cyt C content) and FAs oxidation in particular (diminished β-HAD expression) without increased FAs cellular influx. The aforementioned intervention led to significantly increased TAG cellular level, but not DAG nor CER. Consequently, no changes in cellular insulin responsiveness were noticed. Conclusions: Modest (-24%) PGC-1α protein depletion results in lipid accumulation, without causing insulin resistance. Importantly, it seems that this TAG loading is a result of decreased mitochondrial oxidative capacity and/or possibly increased lipid biosynthesis but not fatty acid cellular influx.

Background/Aims: Liver X receptors (LXRα and LXRβ) are ligand-activated transcription factors that regulate expression of genes involved in lipid and cholesterol metabolism. LXR expression has been identified in human and rodent cardiac tissue, however, its role in this tissue remains unclear. The aim of this study was to investigate effects of in vivo LXR activation on lipid metabolism in the rat myocardium under the conditions of low and high lipid intake. Methods: The experiments were performed on male Wistar rats fed for 5 weeks on either low fat diet (LFD) or high fat diet (HFD). Next, the animals were randomly divided into two groups receiving either LXR agonist - T0901317 (10mg/kg/d) or vehicle for the last week of the experiment. After anesthesia samples of the left ventricle and blood were taken. Results: It was found that LXRβ is the dominant isoform in the rat myocardium and the expression of both LXR isoforms did not change after administration of T0901317. Agonist treatment induced hyperlipidemia in low fat fed rats and this effect was amplified in high fat fed rats. LXR agonist elevated content of myocardial triacylglycerols in animals fed on LFD and content of phospholipids in animals fed on HFD. Levels of the remaining examined lipid classes (nonesterified fatty acids, diacylglycerol, free cholesterol, cholesterol esters, ceramide) was decreased or unchaged after LXR activation. Conclusion: We conclude that administration of T0901317 does not lead to severe myocardial lipid accumulation in rats despite of its high plasma availability.

Ceramide is a key compound in sphingolipid metabolism. Dynamics of ceramide synthesis is important in the several biological processes, such as induction of apoptosis or insulin resistance. So far, its de novo synthesis rate was evaluated indirectly, based on the content of the compound, its intermediates and the activity of respective enzymes. The aim of the present study was to directly measure ceramide synthesis rate (FSR) in different muscle types under varied plasma FFA supply in rat with the use of [U-13C] palmitate tracer and LC/MS/MS. The experiments were carried out on male Wistar rats, divided into three groups: 1-control, 2-with elevated plasma free fatty acid (FFA) concentration by means of intralipid and heparin, 3-with reduced plasma FFA concentration by means of nicotinic acid. The stable plasma FFA concentration and plasma [U-13C] palmitate enrichment was maintained for two hours by simultaneous infusion of the tracer and the respective compounds. At the end of the experiment, samples of blood from the abdominal aorta, the heart, diaphragm, soleus and white section of the gastrocnemius were taken. Muscle sphinganine, sphingosine and ceramide content and enrichment and plasma palmitate enrichment was measured with the use of LC/MS/MS. Plasma FFA concentration and composition was measured by means of gas-liquid chromatography. Under basal conditions ceramide FSR in the heart and the diaphragm was higher than in the soleus and the white gastrocnemius. Elevation in the plasma FFA concentration increased the FSR and ceramide content in each muscle, which correlated with increased HOMA-IR. The highest FSR was noted in the heart. Reduction in the plasma FFA concentration decreased ceramide FSR in each muscle type, which was accompanied by marked reduction in HOMA-IR. It is concluded that ceramide FSR depends on both the muscle type and the plasma FFA supply and is correlated with whole body insulin sensitivity under varying plasma FFA supply.

The aim of the present study was to investigate the time and intensity dependent effects of exercise on the heart components of the lipolytic complex. Wistar rats ran on a treadmill with the speed of 18 m/min for 30 min (M30) or 120 min (M120) or with the speed of 28 m/min for 30 min (F30). The mRNA and protein expressions of the compounds adipose triglyceride lipase (ATGL), comparative gene identification-58 (CGI-58), G0/G1 switch gene 2 (G0S2), hormone sensitive lipase (HSL) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) were examined by real-time PCR and Western blot, respectively. Lipid content of free fatty acids (FFA), diacylglycerols (DG) and triacylglycerols (TG) were estimated by gas liquid chromatography. We observed virtually no changes in the left ventricle lipid contents and only minor fluctuations in its ATGL mRNA levels. This was in contrast with its right counterpart i.e., the content of TG and DG decreased in response to both increased duration and intensity of a run. This occurred in tandem with increased mRNA expression for ATGL, CGI-58 and decreased expression of G0S2. It is concluded that exercise affects behavior of the components of the lipolytic system and the lipid content in the heart ventricles. However, changes observed in the left ventricle did not mirror those in the right one.

Ceramide accumulation in muscle and in liver is implicated in the induction of insulin resistance. Much less in known about the role of ceramide in adipose tissue. The aim of the present study was to elucidate the role of ceramide in adipose tissue and to clarify whether lipids participate in the regulation of adipocytokine secretion. The experiments were performed on male Wistar rats divided into three groups: 1. Control, 2. fed high fat diet (HFD), and 3. fed HFD and treated with myriocin. Ceramide (Cer) and diacylglycerol (DAG) content were analyzed by LC/MS/MS. Hormone sensitive lipase (HSL) phosphorylation was analyzed by Western Blot. Plasma adiponectin and tumor necrosis factor alpha (TNF-α) concentration were measured by enzyme-linked immunosorbent assay. An oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) was also performed. In HFD group, total DAG and Cer content was elevated in both subcutaneous and visceral adipose tissue, which was accompanied by increased glucose, insulin, and HOMA-IR value. Myriocin treatment restored HOMA-IR as well as glucose and insulin concentration to control values. Moreover, myriocin decreased not only Cer, but also DAG levels in both fat depots. Furthermore, we observed a strong correlation between adiponectin (negative) and TNF-α (positive) and Cer in both fat tissues, which suggests that Cer is involved in the regulation of adipocytokine secretion.

Nowadays wrong nutritional habits and lack of physical activity give a rich soil for the development of insulin resistance and obesity. Many researches indicate lipids, especially the one from the sphingolipids class, as the group of molecules heavily implicated in the progress of insulin resistance in skeletal muscle. Recently, scientists have focused their scrutiny on myriocin, a potent chemical compound that inhibits ceramide (i.e., central hub of sphingolipids signaling pathway) de novo synthesis. In the present research we evaluated the effects of myriocin application on type 2 diabetes mellitus in three different types of skeletal muscles: (1) slow-oxidative (red gastrocnemius), (2) oxidative-glycolytic (soleus), and (3) glycolytic (white gastrocnemius). For these reasons the animals were randomly divided into four groups: “control” (C), “myriocin” (M), “high fat diet” (HFD), “high fat diet” (HFD), and “high fat diet + myriocin” (HFD + M). Our in vivo study demonstrated that ceramide synthesis inhibition reduces intramuscular ceramide, its precursor sphinganine, and its derivatives sphingosine and sphingosine-1-phosphate concentrations. Moreover, FFA and TG contents were also decreased after myriocin treatment. Thus, myriocin presents potential therapeutic perspectives with respect to the treatment of insulin resistance and its serious consequences in obese patients.