Fenofibrate lowers lipid accumulation in myotubes by modulating the PPARα/AMPK/FoxO1/ATGL pathway

Promotion of maturation of human pluripotent stem cell-derived cardiomyocytes via treatment with the peroxisome proliferator-activated receptor alpha agonist Fenofibrate

As research on in vitro cardiotoxicity assessment and cardiac disease modeling becomes more important, the demand for human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) is increasing. However, it has been reported that differentiated hPSC-CMs are in a physiologically immature state compared to in vivo adult CMs. Since immaturity of hPSC-CMs can lead to poor drug response and loss of acquired heart disease modeling, various approaches have been attempted to promote maturation of CMs. Here, we confirm that peroxisome proliferator-activated receptor alpha (PPARα), one of the representative mechanisms of CM metabolism and cardioprotective effect also affects maturation of CMs. To upregulate PPARα expression, we treated hPSC-CMs with fenofibrate (Feno), a PPARα agonist used in clinical hyperlipidemia treatment, and demonstrated that the structure, mitochondria-mediated metabolism, and electrophysiology-based functions of hPSC-CMs were all mature. Furthermore, as a result of multi electrode array (MEA)-based cardiotoxicity evaluation between control and Feno groups according to treatment with arrhythmia-inducing drugs, drug response was similar in a dose-dependent manner. However, main parameters such as field potential duration, beat period, and spike amplitude were different between the 2 groups. Overall, these results emphasize that applying matured hPSC-CMs to the field of preclinical cardiotoxicity evaluation, which has become an essential procedure for new drug development, is necessary.

Di-2-ethylhexyl phthalate disrupts hepatic lipid metabolism in obese mice by activating the LXR/SREBP-1c and PPAR-α signaling pathways

Di-2-ethylhexyl phthalate (DEHP), a widely utilized plasticizer, has been described as a potential obesogen based on in vivo disruption of hepatic lipid homeostasis and in vitro promotion of lipid accumulation. However, limited literature exists regarding the specific ramifications of DEHP exposure on obese individuals, and the precise mechanisms underlying the adverse effects of DEHP exposure remain unclear. This study aimed to assess the impact of DEHP on hepatic lipid metabolism in obese mice by comparing them to normal mice. Following a 10-week DEHP exposure period, the obese mice exhibited higher blood lipid levels, more severe hepatic steatosis, and more infiltrations of inflammatory cells in liver tissue than normal mice. Interestingly, the body weight of the mice exhibited no significant alteration. In addition, transcriptomic analyses revealed that both lipogenesis and fatty acid oxidation contributed to hepatic lipid metabolism dysregulation following DEHP exposure. More specifically, alterations in the transcription of genes associated with hepatic lipid metabolism were linked to the different responses to DEHP exposure observed in normal and obese mice. Additionally, the outcomes of in vitro experiments validated the in vivo findings and demonstrated that DEHP exposure could modify hepatic lipid metabolism in normal mice by activating the LXR/SREBP-1c signaling pathway to promote lipogenesis. At the same time, DEHP exposure led to inhibition of the Camkkβ/AMPK pathway to suppress β-fatty acid oxidation. Conversely, in obese mice, DEHP exposure was found to be associated with the stimulation of both lipogenesis and fatty acid oxidation via activation of the LXR/SREBP-1c and PPAR-α signaling pathways, respectively. The findings presented in this study first elucidate the contrasting mechanisms underlying DEHP-induced liver damage in obese and normal mice, thereby offering valuable insights into the pathogenesis of DEHP-induced liver damage in individuals with obesity.

Role of PPARα in inflammatory response of C2C12 myotubes

Recent studies have shown a role of inflammation in muscle atrophy and sarcopenia. However, no anti-inflammatory pharmacotherapy has been established for the treatment of sarcopenia. Here, we investigate the potential role of PPARα and its ligands on inflammatory response and PGC-1α gene expression in LPS-treated C2C12 myotubes. Knockdown of PPARα, whose expression was upregulated upon differentiation, augmented IL-6 or TNFα gene expression. Conversely, PPARα overexpression or its activation by ligands suppressed 2-h LPS-induced cytokine expression, with pemafibrate attenuating NF-κB or STAT3 phosphorylation. Of note, reduction of PGC-1α gene expression by LPS treatment for 24 hours was partially reversed by fenofibrate. Our data demonstrate a critical inhibitory role of PPARα in inflammatory response of C2C12 myotubes and suggest a future possibility of PPARα ligands as a candidate for anti-inflammatory therapy against sarcopenia.

Indian Almond (Terminalia catappa Linn.) Leaf Extract Extends Lifespan by Improving Lipid Metabolism and Antioxidant Activity Dependent on AMPK Signaling Pathway in Caenorhabditis elegans under High-Glucose-Diet Conditions

This study aimed to evaluate the antioxidant and antiaging effects of Indian almond (Terminalia catappa Linn.) leaf extract (TCE) on high-glucose (GLU)-induced obese Caenorhabditis elegans. Since TCE contains high contents of flavonoids and phenolics, strong radical scavenging activity was confirmed in vitro. The stress-resistance effect of TCE was confirmed under thermal and oxidative stress conditions at nontoxic tested concentrations (6.25, 12.5, and 25 μg/mL). GLU at 2% caused lipid and reactive oxygen species (ROS) accumulation in C. elegans, and TCE inhibited lipid and ROS accumulation under both normal and 2% GLU conditions in a concentration-dependent manner. In addition, TCE proved to be effective in prolonging the lifespan of C. elegans under normal and 2% GLU conditions. The ROS reduction effect of TCE was abolished in mutants deficient in daf-16/FOXO and skn-1/Nrf-2. In addition, the lifespan-extending effect of TCE in these two mutants disappeared. The lifespan-extending effect was abolished even in atgl-1/ATGL-deficiency mutants. The TCE effect was reduced in aak-1/AMPK-deficient mutants and completely abolished under 2% GLU conditions. Therefore, the effect of prolonging lifespan by inhibiting lipid and ROS accumulation under the high GLU conditions of TCE is considered to be the result of atgl-1, daf-16, and skn-1 being downregulated by aak-1. These results suggest that the physiological potential of TCE contributes to antiaging under metabolic disorders.

Carnosol analogue WK-63 alleviated cancer cachexia by inhibiting NF-κB and activating AKT pathways in muscle while inhibiting NF-κB and AMPK pathways in adipocyte

Cancer cachexia is a systemic metabolic disorder syndrome characterized by severe wasting of muscle and adipose tissues while is lack of effective therapeutic approaches. Carnosol (CS) was found in our previous study to exhibit ameliorating effects on cancer cachexia. In the present study, we designed and synthesized 49 CS analogues by structural modification of CS. Results of activity screening revealed that, among the analogues, WK-63 exhibited better effects than CS in ameliorating atrophy of C2C12 myotubes induced by conditioned medium of C26 tumor cells. WK-63 could also dose-dependently alleviate adipocyte lipolysis of mature 3 T3-L1 cells induced by C26 tumor cell conditioned medium. WK-63 alleviated myotube atrophy by inhibiting Nuclear Factor kappa-B (NF-κB) and activating the Protein Kinase B (AKT) signaling pathway, and also alleviated fat loss by inhibiting NF-κB and Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) signaling pathways. Results of pharmacokinetic (PK) assay showed that, compared with other analogues, WK-63 exhibited longer half-life (T1/2) and mean residence time (MRTs), as well as a larger concentration curve area (AUC0-t). These findings suggested that WK-63 might exert optimal effects in vivo. In the C26 tumor-bearing mice model, administration of WK-63 ameliorated the body weight loss and also improved the weight loss of epididymal adipose tissue. WK-63 is expected to be a novel therapeutic option for the treatment of cancer cachexia.

Fenofibrate Attenuates Renal Tubular Cell Apoptosis by Up-Regulating MCAD in Diabetic Kidney Disease

Background

Diabetic kidney disease (DKD) is a major diabetic microvascular complication. Fatty acid-induced lipotoxicity and apoptosis were associated with the exacerbation of DKD. However, the association of lipotoxicity with renal tubular apoptosis and the effects of fenofibrate on DKD are not fully understood.

Methods

Eight-week-old db/db mice were given fenofibrate or saline by gavage for 8 weeks. Human kidney proximal tubular epithelial (HK2) cells stimulated with palmitic acid (PA) and high glucose (HG) were used as a model of lipid metabolism disorders. Apoptosis was assessed with or without fenofibrate. The AMP-activated protein kinase (AMPK) activator 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) and AMPK inhibitor Compound C were used to determine the involvement of AMPK and Medium-chain acyl-CoA dehydrogenase (MCAD) in the regulation of lipid accumulation by fenofibrate. MCAD silencing was achieved by small interfering RNA (siRNA) transfection.

Results

Fenofibrate reduced triglyceride (TG) content and lipid accumulation in DKD. Importantly, renal function and tubular cell apoptosis were significantly improved by fenofibrate. Fenofibrate reduced apoptosis, accompanied by increased activation of the AMPK/FOXA2/MCAD pathway. MCAD silencing resulted in apoptosis and lipid accumulation despite fenofibrate treatment.

Conclusion

Fenofibrate improves lipid accumulation and apoptosis through the AMPK/FOXA2/MCAD pathway. MCAD may be a potential therapeutic target of DKD, and the use of fenofibrate as a treatment for DKD warrants further study.

Metformin mitigates renal dysfunction in obese insulin-resistant rats via activation of the AMPK/PPARα pathway

Insulin signaling and lipid metabolism are disrupted by long-term consumption of a high-fat diet (HFD). This disruption can lead to insulin resistance, dyslipidemia and subsequently renal dysfunction as a consequence of the inactivation of the AMP-activated protein kinase (AMPK) and peroxisome proliferator-activated receptor-α (PPARα) or AMPK/PPARα pathways. We investigated the impact of metformin on the prevention of renal dysfunction through the modulation of AMPK-regulated PPARα-dependent pathways in insulin-resistant rats induced by a HFD. Male Wistar rats were fed a HFD for 16 weeks to induce insulin resistance. After insulin resistance had been confirmed, metformin (30 mg/kg) or gemfibrozil (50 mg/kg) was given orally for 8 weeks. Evidence of insulin resistance, dyslipidemia, lipid accumulation and kidney injury were observed in HF rats. Impairment of lipid oxidation, energy metabolism and renal organic anion transporter 3 (Oat3) expression and function were demonstrated in HF rats. Metformin can stimulate the AMPK/PPARα pathways and suppress sterol regulatory element-binding transcription factor 1 (SREBP1) and fatty acid synthase (FAS) signaling (SREBP1/FAS) to enable the regulation of lipid metabolism. Renal inflammatory markers and renal fibrosis expression induced by a HFD were more effectively reduced after metformin treatment than after gemfibrozil treatment. Interestingly, renal Oat3 function and expression and kidney injury were improved following metformin and gemfibrozil treatment. Renal cluster of differentiation 36 (CD36) or sodium glucose cotransporter type 2 (SGLT2) expression did not differ after treatment with metformin or gemfibrozil. Metformin and gemfibrozil could reduce the impairment of renal injury in obese conditions induced by a HFD through the AMPK/PPARα-dependent pathway. Interestingly, metformin demonstrated greater efficacy than gemfibrozil in attenuating renal lipotoxicity through the AMPK-regulated SREBP1/FAS signaling pathway.

Peroxisomal Fitness: A Potential Protective Mechanism of Fenofibrate against High Fat Diet-Induced Non-Alcoholic Fatty Liver Disease in Mice

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) has been increasing in association with the epidemic of obesity and diabetes. Peroxisomes are single membrane-enclosed organelles that play a role in the metabolism of lipid and reactive oxygen species. The present study examined the role of peroxisomes in high-fat diet (HFD)-induced NAFLD using fenofibrate, a peroxisome proliferator-activated receptor α (PPARα) agonist.

METHODS

Eight-week-old male C57BL/6J mice were fed either a normal diet or HFD for 12 weeks, and fenofibrate (50 mg/kg/day) was orally administered along with the initiation of HFD.

RESULTS

HFD-induced liver injury as measured by increased alanine aminotransferase, inflammation, oxidative stress, and lipid accumulation was effectively prevented by fenofibrate. Fenofibrate significantly increased the expression of peroxisomal genes and proteins involved in peroxisomal biogenesis and function. HFD-induced attenuation of peroxisomal fatty acid oxidation was also significantly restored by fenofibrate, demonstrating the functional significance of peroxisomal fatty acid oxidation. In Ppara deficient mice, fenofibrate failed to maintain peroxisomal biogenesis and function in HFD-induced liver injury.

CONCLUSION

The present data highlight the importance of PPARα-mediated peroxisomal fitness in the protective effect of fenofibrate against NAFLD.

Sodium houttuyfonate protects against cardiac injury by regulating cardiac energy metabolism in diabetic rats

Diabetic cardiomyopathy is a diabetic complication with complicated pathophysiological changes and pathogenesis and difficult treatment. Sodium houttuyfonate is the adduct of sodium bisulfite and houttuynin, the main volatile component in Houttuynia cordata Thunb, possesses a variety of activities including multiple interventions on inhibiting ventricular remodeling. The study aims to explore effect of sodium houttuyfonate on diabetic myocardial injury and its underlying mechanisms. The diabetes model was established by intraperitoneal injection of streptozotocin at a dose of 85 mg/kg. By intragastric administration for 26 days, sodium houttuyfonate (50 and 100 mg/kg/d) reversed the abnormal serum levels of triglyceride, total cholesterol, low-density lipoprotein cholesterol and low-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio, improved the abnormal levels of serum aspartate aminotransferase and brain natriuretic peptide, reduced electrocardiogram P-R and QRS interval extension, accelerated the heart rate, decreased serum malondialdehyde content, up-regulated the myocardial energy metabolism including elevated the contents of ATP, ADP, total adenine nucleotides and phosphocreatine in myocardium, decreased AMP/ATP ratio, elevated myocardial Ca²⁺-Mg²⁺-ATPase activity, and down-regulated the mRNA expressions of AMP protein activation kinase α₂ (AMPK-α₂) and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α). In a conclusion, these results suggest that sodium houttuyfonate can improve cardiac energy metabolism disorder caused by diabetes by increasing cardiac Ca²⁺-Mg²⁺-ATPase activity and regulating AMPK signaling pathway, and then attenuates cardiac injury caused by hyperglycemia. In addition, sodium houttuyfonate also has the effects of anti-oxidation and improving abnormal levels of blood lipid.

PPARα agonist fenofibrate relieves acquired resistance to gefitinib in non-small cell lung cancer by promoting apoptosis via PPARα/AMPK/AKT/FoxO1 pathway

Recent studies show that intracellular accumulation of cholesterol leads to acquired resistance to gefitinib in non-small cell lung cancer (NSCLC) cells. In this study we investigated how to regulate the cholesterol levels in gefitinib-resistant NSCLC cells. We showed that intracellular cholesterol levels in gefitinib-resistant cell lines (PC-9/GR, H1975, H1650, and A549) were significantly higher than that in gefitinib-sensitive cell line (PC-9). Treatment with gefitinib (5 μM) significantly increased intracellular cholesterol levels in PC-9/GR, H1975, and H1650 cells. Gefitinib treatment downregulated the expression of PPARα, LXRα, and ABCA1, leading to dysregulation of cholesterol efflux pathway. We found that a lipid-lowering drug fenofibrate (20, 40 μM) dose-dependently increased the expression of PPARα, LXRα, and ABCA1, decreased the intracellular cholesterol levels, and enhanced the antiproliferative effects of gefitinib in PC-9/GR, H1975, and H1650 cells. We revealed that fenofibrate increased the gefitinib-induced apoptosis via regulating the key proteins involved in the intrinsic apoptosis pathway. In PC-9/GR, H1975 and H1650 cells, fenofibrate dose-dependently increased the expression of AMPK, FoxO1, and decreased the expression of AKT, which were remarkably weakened by knockdown of PPARα. In PC-9/GR cell xenograft mice, combined administration of gefitinib (25 mg · kg^-1 · d^-1) and fenofibrate (100 mg · kg^-1 · d^-1) caused remarkable inhibition on tumor growth as compared to treatment with either drug alone. All the results suggest that fenofibrate relieves acquired resistance to gefitinib in NSCLC by promoting apoptosis via regulating PPARα/AMPK/AKT/FoxO1 pathway. We propose that combination of gefitinib and fenofibrate is a potential strategy for overcoming the gefitinib resistance in NSCLC.

Rhus chinensis Mill. Fruits Ameliorate Hepatic Glycolipid Metabolism Disorder in Rats Induced by High Fat/High Sugar Diet

Hepatic glycolipid metabolism disorder is considered as one of the key factors in the pathogenesis of many chronic diseases. The objective of this study was to investigate the protective effect and underlying mechanisms of Rhus chinensis Mill. fruits against hepatic glycolipid metabolic disorders in rats induced by a high fat/high sugar diet. Results showed that ethanol extract, especially at a dose of 600 mg/kg b.w., could effectively ameliorate glycolipid metabolic disorders in rats. The biochemical indexes, including CAT, GSH and HOMA-IR, were significantly improved by the administration of ethanol extract. Immunohistochemistry and Western blot analysis revealed that ethanol extract up-regulated the expression levels of PI3K/AKT, PPAR-α, and the phosphorylation of IRS1 and AMPK proteins, and down-regulated the expressions of SREBP-1 and FAS proteins in the liver, which are closely related to hepatic glycolipid metabolism. Those findings suggested that R. chinensis Mill. fruits could be developed as functional foods and/or nutraceuticals for preventing or controlling some chronic diseases related to hepatic glycolipid metabolism disorder.

A new therapeutic effect of fenofibrate in Duchenne muscular dystrophy: The promotion of myostatin degradation

BACKGROUND AND PURPOSE

Duchenne muscular dystrophy (DMD) is a degenerative muscle disease with no effective drug treatment. This study investigated the positive effects of fenofibrate on dystrophic muscles.

EXPERIMENTAL APPROACH

Myostatin expression in serum and muscle tissue of DMD patients and mdx mice were tested. Primary myoblasts isolated from mdx mice were challenged with an inflammatory stimulus and treated with fenofibrate. In animal experiments, 6-week-old male mdx mice were treated with fenofibrate (100 mg/kg) administered orally once per day for 6 weeks. Tests of muscle function plus histology and biochemical analyses of serum were conducted to evaluate the effects of fenofibrate. The expressions of myostatin, MuRF1, and atrogin-1 in skeletal muscle were evaluated by Western blotting and real-time PCR. Total and oxidative myosin heavy chain (MHC) were assessed via immunofluorescence.

KEY RESULTS

Increased expression of myostatin protein was found in dystrophic muscle of DMD patients and mdx mice. Fenofibrate enhanced myofibre differentiation by downregulating the expression of myostatin protein but not mRNA in primary myoblasts of mdx mice. Fenofibrate significantly improved muscle function while ameliorating muscle damage in mdx mice. These benefits are accompanied by an anti-inflammatory effect. Fenofibrate treatment returned myofibre function by inhibiting the expressions of myostatin, MuRF1, and atrogin-1 protein in the gastrocnemius muscle and diaphragm, while leaving the mRNA level of myostatin unaffected.

CONCLUSIONS AND IMPLICATIONS

Fenofibrate substantially slows muscle dystrophy by promoting the degradation of myostatin protein, which may indicate a new therapeutic focus for DMD patients.

When Activator and Inhibitor of PPARα Do the Same: Consequence for Differentiation of Human Intestinal Cells

Peroxisome proliferator-activated receptor α (PPARα) is a ligand-dependent transcription factor that plays a role in various processes including differentiation of several cell types. We investigated the role of PPARα in the differentiation of intestinal cells using HT-29 and Caco2 cell lines as a model as well as human normal colon and colorectal carcinoma tissues. We detected a significant increase in PPARα expression in differentiated HT-29 cells as well as in normal surface colon epithelium where differentiated cells are localised. Thus, it seems that PPARα may play a role in differentiation of intestinal cells. Interestingly, we found that both PPARα activators (fenofibrate and WY-14643) as well as its inhibitor (GW6471) regulated proliferation and differentiation of HT-29 cells in vitro in the same way. Both compounds led to a decrease in proliferation accompanied by a significant increase in expression of villin, intestinal alkaline phosphatase (differentiation markers). Moreover, the same trend in villin expression was observed in Caco2 cells. Furthermore, villin expression was independent of subcellular localisation of PPARα. In addition, we found similar levels of PPARα expression in colorectal carcinomas in comparison to adjacent normal epithelium. All these findings support the hypothesis that differentiation of intestinal epithelium is PPARα-independent.

Animal Fatty Acid Synthase: A Chemical Nanofactory

Fatty acids are crucial molecules for most living beings, very well spread and conserved across species. These molecules play a role in energy storage, cell membrane architecture, and cell signaling, the latter through their derivative metabolites. De novo synthesis of fatty acids is a complex chemical process that can be achieved either by a metabolic pathway built by a sequence of individual enzymes, such as in most bacteria, or by a single, large multi-enzyme, which incorporates all the chemical capabilities of the metabolic pathway, such as in animals and fungi, and in some bacteria. Here we focus on the multi-enzymes, specifically in the animal fatty acid synthase (FAS). We start by providing a historical overview of this vast field of research. We follow by describing the extraordinary architecture of animal FAS, a homodimeric multi-enzyme with seven different active sites per dimer, including a carrier protein that carries the intermediates from one active site to the next. We then delve into this multi-enzyme's detailed chemistry and critically discuss the current knowledge on the chemical mechanism of each of the steps necessary to synthesize a single fatty acid molecule with atomic detail. In line with this, we discuss the potential and achieved FAS applications in biotechnology, as biosynthetic machines, and compare them with their homologous polyketide synthases, which are also finding wide applications in the same field. Finally, we discuss some open questions on the architecture of FAS, such as their peculiar substrate-shuttling arm, and describe possible reasons for the emergence of large megasynthases during evolution, questions that have fascinated biochemists from long ago but are still far from answered and understood.

Astilbin lowers the effective caffeine dose for decreasing lipid accumulation via activating AMPK in high-fat diet-induced obese mice

BACKGROUND

Caffeine has an anti-obesity effect, although chronic excessive caffeine consumption also causes caffeinism, which is marked by increased anxiety or depression, amongst other symptoms. The present study aimed to investigate whether the addition of flavonoids such as astilbin can reduce the caffeine dose needed to inhibit obesity.

RESULTS

ICR mice (n = 80) were fed with normal diet, high-fat diet (HFD), HFD supplemented with astilbin, caffeine, or astilbin + caffeine for 12 weeks. When diets supplemented with astilbin, 0.3 g kg^-1 diet caffeine had the same effect as 0.6 g kg^-1 diet caffeine alone, and 0.6 g kg^-1 diet caffeine combined with astilbin most effectively inhibited HFD-induced obesity. Astilbin improved the anti-obesity effects of caffeine on lipid accumulation via the activation of AMP-activated protein kinase α (AMPKα). (i) Activated AMPKα decreased lipid biosynthesis by suppressing the activity or mRNA expression of 3-hydroxy-3-methylglutaryl-CoA reductase, sterol regulatory element binding protein 1c and its target gene fatty acid synthase. (ii) Activated AMPKα also up-regulated lipolysis by enhancing the expression of adipose triglyceride lipase and increasing the phosphorylation of hormone-sensitive lipase. (iii) Finally, activated AMPKα increased carnitine acyltransferase and acyl-CoA oxidase activities, which further promoted fatty acid β-oxidation.

CONCLUSION

The results obtained in the present study indicate that astilbin may decrease the effective dose of caffeine needed for an anti-obesity effect and also suggest that it suppresses fat accumulation via the activation of AMPK. © 2020 Society of Chemical Industry.

Effects of fenofibrate and its combination with lovastatin on the expression of genes involved in skeletal muscle atrophy, including FoxO1 and its targets

Fibrates and statins have been widely used to reduce triglyceride and cholesterol levels, respectively. Besides its lipid-lowering effect, the side effect of muscle atrophy after fibrate administration to humans has been demonstrated in some studies. Combination therapy with fibrates and statins also increases the risk of rhabdomyolysis. FoxO1, a member of the FoxO forkhead type transcription factor family, is markedly upregulated in skeletal muscle in energy-deprived states and induces muscle atrophy via the expression of E3-ubiquitine ligases. In this study, we investigated the changes in FoxO1 and its targets in murine skeletal muscle with fenofibrate treatment. High doses of fenofibrate (greater than 0.5% (wt/wt)) over one week increased the expression of FoxO1 and its targets in the skeletal muscles of mice and decreased skeletal muscle weight. These fenofibrate-induced changes were diminished in the PPARα knockout mice. When the effect of combination treatment with fenofibrate and lovastatin was investigated, a significant increase in FoxO1 protein levels was observed despite the lack of deterioration of muscle atrophy. Collectively, our findings suggest that a high dose of fenofibrate over one week causes skeletal muscle atrophy via enhancement of FoxO1, and combination treatment with fenofibrate and lovastatin may further increase FoxO1 protein level.

In Vivo Antifatigue Activity of Spirulina Peptides Achieved by Their Antioxidant Activity and by Acting on Fat Metabolism Pathway in Mice

Spirulina are multicellular and filamentous cyanobacteria that have achieved considerable popularity in the health sector, food industry, and aquaculture. In the present study, we aimed to evaluate the antifatigue effects of Spirulina-derived peptides on Institute for Cancer Research mice and explore the association between antifatigue activity and fat metabolism involving the adenosine monophosphate-activated protein kinase (AMPK) signaling pathway. We extracted the peptides from Spirulina by enzymatic hydrolysis and ultrafiltration. The mice were orally administered with Spirulina peptides (0.125, 0.5, and 2 mg/g bw/day) daily for 4 weeks. We found that Spirulina peptides, especially the high-dose group, significantly prolonged the swimming time by 126.1%, increased the activities of antioxidant enzymes, and decreased the content of malondialdehyde by 60.2% compared with the glutathione (GSH) group. The levels of some indicators of exercise fatigue, including lactic dehydrogenase, blood lactic acid, and creatine phosphokinase, were reduced. In the high-dose group, these indicators were reduced by 40.7%, 22.3%, and 11.3% compared with the GSH group. Spirulina peptides did not excessively consume blood sugar or glycogen in the liver and muscle to produce energy. However, the triglyceride level was reduced, and the level of free fatty acids was increased. Besides, the proteins in the AMPK signaling pathway were activated. Taken together, these findings indicated that Spirulina peptides could effectively alleviate physical fatigue by reducing the production of lactic acid and improving antioxidant capacity. Spirulina peptides also helped increase the energy resources by activating the AMPK signaling pathway to utilize fat metabolism.

Evaluation of the Relationship between Adipose Metabolism Patterns and Secretion of Appetite-Related Endocrines on Chicken

Simple Summary

The weight of an animal conforms to a certain growth pattern. Among others, feed, environment, and body composition, in addition to genetics, affect the animal’s feed consumption and body weight. Under normal circumstances, the body weight of an animal is mainly affected by feed intake, and body composition may significantly influence feed intake. Therefore, this report sets out the effects of fat accumulation on lipid metabolism and appetite, and finally introduces the effects of feeding patterns on animal feed intake.

Abstract

In addition to the influence of genes, the quality of poultry products is mainly controlled by the rearing environment or feed composition during rearing, and has to meet human use and economical needs. As the only source of energy for poultry, feed considerably affects the metabolic pattern of poultry and further affects the regulation of appetite-related endocrine secretion in poultry. Under normal circumstances, the accumulation of lipid in adipose reduces feed intake in poultry and increases the rate of adipose metabolism. When the adipose content in cells decreases, endocrines that promote food intake are secreted and increase nutrient concentrations in serum and cells. By regulating the balance between appetite and adipose metabolism, the poultry’s growth and posture can maintain a balanced state. In addition, increasing fiber composition in feed can effectively increase poultry welfare, body weight, lean composition and antioxidant levels in poultry. According to this, the concept that proper fiber content should be added to feed should be considered for better economic benefits, poultry welfare and meat productivity.

Fenofibrate induces human hepatoma Hep3B cells apoptosis and necroptosis through inhibition of thioesterase domain of fatty acid synthase

This study demonstrated that fenofibrate, a lipid-lowering drug, induced a significant time-dependent cytotoxicity of hepatoma Hep3B cells. Hep3B cells are significantly more sensitive to cell killing by fenofibrate than hepatoma HepG2, lung cancer CH27 and oral cancer HSC-3 cells. From the result of docking simulation, fenofibrate can bind excellently to the thioesterase domain of fatty acid synthase (FASN) binding site as orlistat, a FASN inhibitor, acts. The fenofibrate-induced cell cytotoxicity was protected by addition of palmitate, indicating that the cytotoxic effect of fenofibrate is due to starvation of Hep3B cells by inhibiting the formation of end product in the FASN reaction. Inhibition of lipid metabolism-related proteins expression, such as proteins containing thioesterase domain and fatty acid transport proteins, was involved in the fenofibrate-induced Hep3B cell death. Fenofibrate caused S and G2/M cell cycle arrest by inducing cyclin A/Cdk2 and reducing cyclin D1 and E protein levels in Hep3B cells. The anti-tumor roles of fenofibrate on Hep3B cells by inducing apoptosis and necroptosis were dependent on the expression of Bcl-2/caspase family members and RIP1/RIP3 proteins, respectively. These results suggest that fenofibrate has an anti-cancer effect in Hep3B cells and inhibition of lipid metabolism may be involved in fenofibrate-induced Hep3B cells apoptosis and necroptosis.

Nanotized PPARα Overexpression Targeted to Hypertrophied Myocardium Improves Cardiac Function by Attenuating the p53-GSK3β-Mediated Mitochondrial Death Pathway

AIMS

Metabolic remodeling of cardiac muscles during pathological hypertrophy is characterized by downregulation of fatty acid oxidation (FAO) regulator, peroxisome proliferator-activated receptor alpha (PPARα). Thereby, we hypothesized that a cardiac-specific induction of PPARα might restore the FAO-related protein expression and resultant energy deficit. In the present study, consequences of PPARα augmentation were evaluated for amelioration of chronic oxidative stress, myocyte apoptosis, and cardiac function during pathological cardiac hypertrophy.

RESULTS

Nanotized PPARα overexpression targeted to myocardium was done by a stearic acid-modified carboxymethyl-chitosan (CMC) conjugated to a 20-mer myocyte-targeted peptide (CMCP). Overexpression of PPARα ameliorated pathological hypertrophy and improved cardiac function. Augmented PPARα in hypertrophied myocytes revealed downregulated p53 acetylation (lys 382), leading to reduced apoptosis. Such cells showed increased binding of PPARα with p53 that in turn reduced interaction of p53 with glycogen synthase kinase-3β (GSK3β), which upregulated inactive phospho-GSK3β (serine [Ser]9) expression within mitochondrial protein fraction. Altogether, the altered molecular milieu in PPARα-overexpressed hypertrophy groups restored mitochondrial structure and function both in vitro and in vivo.

INNOVATION

Cardiomyocyte-targeted overexpression of a protein of interest (PPARα) by nanotized plasmid has been described for the first time in this study. Our data provide a novel insight towards regression of pathological hypertrophy by ameliorating mitochondrial oxidative stress in targeted PPARα-overexpressed myocardium.

CONCLUSION

PPARα-overexpression during pathological hypertrophy showed substantial betterment of mitochondrial structure and function, along with downregulated apoptosis. Myocardium-targeted overexpression of PPARα during pathological cardiac hypertrophy led to an overall improvement of cardiac energy deficit and subsequent cardiac function, thereby, opening up a potential avenue for cardiac tissue engineering during hypertrophic cardiac pathophysiology.

Quercetin Reverses Altered Energy Metabolism in the Heart of Rats Receiving Adriamycin Chemotherapy

The primary aim of this study was to find the potential modulatory roles of quercetin (QUE) against Adriamycin (ADR)-induced cardiotoxicity. A total of 50 rats were assigned to five groups: a control group, an ADR-treated group, a QUE-treated group, a prophylaxis-cotreated group, and a therapeutic-cotreated group, respectively. QUE exhibited a significant cardioprotective effect, particularly, when it was administered prior to and concurrently with ADR treatment (prophylaxis-cotreated group). This effect was biochemically evident by the significant decreases in the serum levels of myocardial injury biomarkers such as troponin, creatine kinase-myocardium bound, and creatine phosphokinase. In addition, significant elevations in myocardial antioxidant indices coupled with significant reductions in myocardial malondialdehyde contents and DNA damage, elicited by ADR injection, were observed. All these biochemical improvements were accompanied by a significant histopathological recovery and obvious modulation of the AMP-activated protein kinase (AMPK) signaling pathway by promoting the expression of the AMPKα2, PPARα, and PCG-1α genes. Taken together, these findings conclusively showed that QUE administration through its antioxidant capacity and myocardial energy metabolism restoration provides a prophylactic effect in response to ADR-induced deleterious effects, in the rat heart.

Dietary supplement of Smilax china L. ethanol extract alleviates the lipid accumulation by activating AMPK pathways in high-fat diet fed mice

Background

Obesity has become a public health concern worldwide because it is linked to numerous metabolic disorders, such as hyperlipidemia, hypertension and cardiovascular disease. Therefore, there is an urgent need to develop new therapeutic strategies that are efficacious and have minimal side effects in obesity treatment. This study examined the effect of dietary supplement of Smilax china L. ethanol extract (SCLE) on high-fat diet (HFD) induced obesity.

Methods

Fifty ICR mice were fed a normal diet, high-fat diet (HFD) or HFD supplemented with 0.25, 0.5% or 1% SCLE for 8 weeks. Body weight, intraperitioneal adipose tissue (IPAT) weight, serum biochemical parameters, and liver lipids were measured. Activity, mRNA and protein expressions of lipid metabolism-related enzymes were analyzed.

Results

Over 0.5% SCLE had reduced cholesterol biosynthesis by the activation of AMP-activated protein kinase (AMPK), which subsequently suppressed the mRNA expression of both sterol regulatory element binding protein-2 and 3-hydroxy-3-methyl-glutaryl-CoA reductase. Thus, the plasma and liver cholesterol concentrations in the HFD-fed mice were decreased. AMPK activation caused by SCLE also significantly upregulated lipolysis by enhancing adipose triglyceride lipase and hormone-sensitive lipase activities. This accelerated triglyceride hydrolysis and fatty acid release. Finally, SCLE increased carnitine palmitoyltransferase 1 and acyl-CoA oxidase activities, which further promoted fatty acid β-oxidation.

Conclusion

SCLE could lead to a decrease in body weight gain and fat mass by inhibiting the lipid synthesis and promoting lipolysis and β-oxidation in HFD fed mice. The underlying mechanism is probably associated with regulating AMPK pathway.

An attempt to reverse cardiac lipotoxicity by aerobic interval training in a high-fat diet- and streptozotocin-induced type 2 diabetes rat model

BACKGROUND

Diabetes mellitus (DM) is an important risk factor for cardiovascular disease. Aerobic interval training (AIT) has been recommended to patients as a non-pharmacological strategy to manage DM. However, little is known about whether AIT intervention at the onset of DM will reverse the process of diabetic cardiomyopathy (DCM). In this study, we sought to evaluate whether AIT can reverse the process of DCM and explore the underlying mechanisms.

METHODS

Fifty Wistar rats were randomly divided into a control group (CON), DCM group (DCM) and AIT intervention group (AIT). A high-fat diet and streptozotocin (STZ) were used to induce diabetes in rats in the DCM group and AIT group. Rats in the AIT group were subjected to an 8-week AIT intervention. Fasting blood glucose (FBG), lipid profiles and insulin levels were measured. Haematoxylin and eosin (HE) staining and oil red O staining were used to identify cardiac morphology and lipid accumulation, respectively. Serum BNP levels and cardiac BNP mRNA expression were measured to ensure the safety of the AIT intervention. Free fatty acid (FFA) and diacylglycerol (DAG) concentrations were analysed by enzymatic methods. AMPK, p-AMPK, FOXO1, CD36 and PPARα gene and protein expression were detected by RT-PCR and Western blotting.

RESULTS

AIT intervention significantly reduced rat serum cardiovascular disease risk factors in DCM rats (P < 0.05). The safety of AIT intervention was illustrated by reduced serum BNP levels and cardiac BNP mRNA expression (P < 0.05) after AIT intervention in DCM rats histological analysis and FFA and DAG concentrations revealed that AIT intervention reduced the accumulation of lipid droplets within cardiomyocytes and alleviated cardiac lipotoxicity (P < 0.05). CD36 and PPARα gene and protein expression were elevated in the DCM group, and these increases were reduced by AIT intervention (P < 0.01). The normalized myocardial lipotoxicity was due to increased expression of phosphorylated AMPK and reduced FOXO1 expression after AIT intervention.

CONCLUSION

AIT intervention may alleviate cardiac lipotoxicity and reverse the process of DCM through activation of the AMPK-FOXO1 pathway.

The protein-sparing effect of α-lipoic acid in juvenile grass carp, Ctenopharyngodon idellus: effects on lipolysis, fatty acid β-oxidation and protein synthesis

To investigate the protein-sparing effect of α-lipoic acid (LA), experimental fish (initial body weight: 18·99 (sd 1·82) g) were fed on a 0, 600 or 1200 mg/kg α-LA diet for 56 d, and hepatocytes were treated with 20 μm compound C, the inhibitor of AMP kinase α (AMPKα), treated for 30 min before α-LA treatment for 24 h. LA significantly decreased lipid content of the whole body and other tissues (P<0·05), and it also promoted protein deposition in vivo (P<0·05). Further, dietary LA significantly decreased the TAG content of serum and increased the NEFA content of serum (P<0·05); however, there were no significant differences among all groups in the hepatopancreas and muscle (P>0·05). Consistent with results from the experiment in vitro, LA activated phosphorylation of AMPKα and notably increased the protein content of adipose TAG lipase in intraperitoneal fat, hepatopancreas and muscle in vivo (P<0·05). Meanwhile, LA significantly up-regulated the mRNA expression of genes involved in fatty acid β-oxidation in the same three areas, and LA also obviously down-regulated the mRNA expression of genes involved in amino acid catabolism in muscle (P<0·05). Besides, it was observed that LA significantly activated the mammalian target of rapamycin (mTOR) pathway in muscle of experimental fish (P<0·05). LA could promote lipolysis and fatty acid β-oxidation via increasing energy supply from lipid catabolism, and then, it could economise on the protein from energy production to increase protein deposition in grass carp. Besides, LA might directly promote protein synthesis through activating the mTOR pathway.

Protective role of fenofibrate in sepsis-induced acute kidney injury in BALB/c mice

Acute kidney injury (AKI) is a severe complication of sepsis, which largely contributes to the associated high mortality rate. Fenofibrate, a peroxisome proliferator activated receptor α (PPARα) agonist, has received considerable attention because of its effects related to renal damage-related energy metabolism and inflammation. The present study investigated the effects of fenofibrate on sepsis-associated AKI in BALB/c mice subjected to caecal ligation and puncture (CLP). Eight-week-old male BALB/c mice were divided into four groups: control group, fenofibrate group, caecal ligation and puncture (CLP) group, and fenofibrate + CLP group. CLP was performed after mice were gavaged with fenofibrate for 2 weeks. After 48 hours, we measured the histopathological alterations of the kidney tissue and plasma levels of serum creatinine (CRE), neutrophil gelatinase-associated lipocalin (NGAL), reactive oxygen species (ROS), ATP, and ADP. We evaluated PPARα and P53 protein levels as well as interleukin (IL)-1β, IL-6, and tumour necrosis factor-α mRNA levels. Our results showed that administering fenofibrate significantly reduced kidney histological alterations caused by CLP. Fenofibrate inhibited the plasma levels of ROS, CRE, NGAL, and increased the ATP/ADP ratio. Fenofibrate significantly inhibited elevations in P53, IL-1β, IL-6, and tumour necrosis factor-α expression. The results suggest that fenofibrate administration effectively modulates energy metabolism and may be a novel approach to treat sepsis-induced renal damage.

Effect of fermented Cordyceps sinensis on doxorubicin‑induced cardiotoxicity in rats

Cordyceps sinensis (CS) is a prominent medicinal herb in traditional Chinese medicine, and fermented CS is frequently used as a substitute for natural CS. Doxorubicin (DOX), an antitumor drug used in chemotherapy, is limited by its poor cardiotoxicity. The aim of the present study was to evaluate the protective effect of fermented CS against DOX-induced cardiotoxicity and the potential underlying mechanisms. Male Sprague-Dawley rats (180–200 g) were randomly assigned to seven different treatment groups: Normal control, DOX control, DOX+captopril (0.05 g/kg), 0.75, 1.5 and 3 g/kg DOX+CS, and the CS (1.5 g/kg) control. Histopathological changes, cardiac energy metabolism, cyclic adenosine monophosphate (cAMP) signaling and the associated mRNA expression of AMP-activated protein kinase (AMPK) were then evaluated. Fermented CS decreased the left ventricular weight index, heart weight index and mortality; however, it increased diastolic blood pressure and mean arterial pressure. In addition, it shortened the duration of the QRS complex and Sα-T segment, decreased serum creatine kinase (CK) and aspartate aminotransferase activity, inhibited histopathological changes and reduced brain natriuretic peptide content. Treatment with fermented CS also increased the activities of superoxide dismutase and glutathione peroxidase, reduced malondialdehyde content, increased the mitochondrial activities of Na⁺K⁺-adenosine 5′-triphosphate (ATP) ase, Ca²⁺Mg²⁺-ATPase and CK, and increased the creatine phosphate/ATP ratio and AMP/ATP ratio. Furthermore, it decreased the ATP/adenosine 5′-diphosphate (ADP) ratio, upregulated AMPKα2 expression, reduced the activity of serum phosphodiesterases (PDEs) and increased myocardial cAMP content. The results of the present study demonstrated that fermented CS attenuated DOX-induced cardiotoxicity by inhibiting myocardial hypertrophy and myocardial damage, ameliorating systolic function and the antioxidant enzyme system, improving cardiac energy metabolism, depressing the activities of PDEs, and by upregulating the cAMP and AMPK signaling pathways. Thus, fermented CS may be a candidate for the prevention of DOX-induced cardiotoxicity, cardiac energy impairment and against a number of cardiac diseases.

Pioglitazone Enhances Cytosolic Lipolysis, β-oxidation and Autophagy to Ameliorate Hepatic Steatosis

Non-alcoholic fatty liver disease closely contributes to the development of obesity and insulin resistance. Even though pioglitazone has been reported to effectively lessen hepatic steatosis in human studies, its molecular mechanism remains unclear. This study is designed to investigate the regulation of cytosolic lipolysis, β-oxidation and autophagy by pioglitazone in a mice model of high fat diet (HFD) and cell model incubated with palmitic acid. Our results revealed hepatic steatosis was apparently induced by HFD and it was significantly reversed by pioglitazone. The serum insulin and hepatic triglyceride content was significantly decreased by co-administered pioglitazone with HFD. Hepatic expression of cytosolic-lipolysis related proteins (ATGL, HSL), β-oxidation (CPT-1A) and autophagy-related proteins (ATG7, LC3, LAL) was significantly enhanced by pioglitazone. Knockdown PPARα/PPARγ in AML12 cells significantly and proportionally reduced the expressions of ATGL, CPT-1A and LC3II, which was induced by pioglitazone. Furthermore, facilitation of the autophagic flux by pioglitazone was obviously blocked by lysosomal inhibitor, leupeptin, to demonstrate accumulation of the LC3II and intracellular lipid in AML12 cells. Our results demonstrated that pioglitazone attenuating the hepatic steatosis may be mediated by enhancing cytosolic lipolysis, β-oxidation and autophagy in a PPARα and PPARγ dependent manner.

Eicosapentaenoic acid down-regulates expression of the selenoprotein P gene by inhibiting SREBP-1c protein independently of the AMP-activated protein kinase pathway in H4IIEC3 hepatocytes

Selenoprotein P (encoded by SELENOP in humans, Selenop in rat), a liver-derived secretory protein, induces resistance to insulin and vascular endothelial growth factor (VEGF) in type 2 diabetes. Suppression of selenoprotein P may provide a novel therapeutic approach to treating type 2 diabetes; however, few drugs inhibiting SELENOP expression in hepatocytes have been identified. The present findings demonstrate that eicosapentaenoic acid (EPA) suppresses SELENOP expression by inactivating sterol regulatory element-binding protein-1c (SREBP-1c, encoded by Srebf1 in rat) in H4IIEC3 hepatocytes. Treatment with EPA caused concentration- and time-dependent reduction in SELENOP promoter activity. EPA activated AMP-activated protein kinase (AMPK); however, the inhibitory effect of EPA on SELENOP promoter activity was not canceled with an AMPK inhibitor compound C and dominant-negative AMPK transfection. Deletion mutant promoter assays and computational analysis of transcription factor-binding sites conserved among the species resulted in identification of a sterol regulatory element (SRE)-like site in the SELENOP promoter. A chromatin immunoprecipitation (ChIP) assay revealed that EPA decreases binding of SREBP-1c to the SELENOP promoter. Knockdown of Srebf1 resulted in a significant down-regulation of Selenop expression. Conversely, SREBP-1c overexpression inhibited the suppressive effect of EPA. These data provide a novel mechanism of action for EPA involving improvement of systemic insulin sensitivity through the regulation of selenoprotein P production independently of the AMPK pathway and suggest an additional approach to developing anti-diabetic drugs.

AMPK regulates lipid accumulation in skeletal muscle cells through FTO-dependent demethylation of N6-methyladenosine

Skeletal muscle plays important roles in whole-body energy homeostasis. Excessive skeletal muscle lipid accumulation is associated with some metabolic diseases such as obesity and Type 2 Diabetes. The energy sensor AMPK (AMP-activated protein kinase) is a key regulator of skeletal muscle lipid metabolism, but the precise regulatory mechanism remains to be elucidated. Here, we provide a novel mechanism by which AMPK regulates skeletal muscle lipid accumulation through fat mass and obesity-associated protein (FTO)-dependent demethylation of N6-methyladenosine (m6A). We confirmed an inverse correlation between AMPK and skeletal muscle lipid content. Moreover, inhibition of AMPK enhanced lipid accumulation, while activation of AMPK reduced lipid accumulation in skeletal muscle cells. Notably, we found that mRNA m6A methylation levels were inversely correlated with lipid content in skeletal muscle. Furthermore, AMPK positively regulated the m6A methylation levels of mRNA, which could negatively regulate lipid accumulation in C2C12. At the molecular level, we demonstrated that AMPK regulated lipid accumulation in skeletal muscle cells by regulating FTO expression and FTO-dependent demethylation of m6A. Together, these results provide a novel regulatory mechanism of AMPK on lipid metabolism in skeletal muscle cells and suggest the possibility of controlling skeletal muscle lipid deposition by targeting AMPK or using m6A related drugs.

PPARα-ATGL pathway improves muscle mitochondrial metabolism: implication in aging

Adipose triglyceride lipase (ATGL) maintains an optimum mitochondrial function putatively by generating cognate ligands for peroxisome proliferator-activated receptor α (PPARα), which, together with PPARγ coactivator-1α (PGC1α), regulate muscle mitochondrial biogenesis. However, the cross-talk between ATGL and PPARα in skeletal muscle mitochondrial metabolism and its implication in chronological aging is poorly understood. The role of ATGL in muscle mitochondrial metabolism was studied by overexpressing and depleting the gene and studying its downstream effect in cultured myotubes and in murine skeletal muscle. We found that PPARα directly induces ATGL expression during myogenesis. Overexpression of ATGL significantly enhanced while depletion of ATGL attenuated mitochondrial oxidative phosphorylation and fatty acid oxidation without alteration in mitochondrial content, and it rendered PPARα and PGC1α redundant in promoting mitochondrial oxidative function. However, ATGL did not alter PPARα-dependent lipid accumulation and insulin sensitivity. In middle-aged rats, ATGL expression was higher and correlated with PPARα expression and sustained fatty acid oxidation in oxidative soleus muscle. Fenofibrate feeding further induced ATGL expression selectively in this muscle compartment. These findings illustrate that PPARα and ATGL constitute a regulatory pathway in skeletal muscle, suggesting their role as a mitochondrial metabolic reserve.-Biswas, D., Ghosh, M., Kumar, S., Chakrabarti, P. PPARα-ATGL pathway improves muscle mitochondrial metabolism: implication in aging.

Delayed treatment with fenofibrate protects against high-fat diet-induced kidney injury in mice: the possible role of AMPK autophagy

Fenofibrate activates not only peroxisome proliferator-activated receptor-α (PPARα) but also adenosine monophosphate-activated protein kinase (AMPK). AMPK-mediated cellular responses protect kidney from high-fat diet (HFD)-induced injury, and autophagy resulting from AMPK activation has been regarded as a stress-response mechanism. Thus the present study examined the role of AMPK and autophagy in the renotherapeutic effects of fenofibrate. C57BL/6J mice were divided into three groups: normal diet (ND), HFD, and HFD + fenofibrate (HFD + FF). Fenofibrate was administered 4 wk after the initiation of the HFD when renal injury was initiated. Mouse proximal tubule cells (mProx24) were used to clarify the role of AMPK. Feeding mice with HFD for 12 wk induced insulin resistance and kidney injury such as albuminuria, glomerulosclerosis, tubular injury, and inflammation, which were effectively inhibited by fenofibrate. In addition, fenofibrate treatment resulted in the activation of renal AMPK, upregulation of fatty acid oxidation (FAO) enzymes and antioxidants, and induction of autophagy in the HFD mice. In mProx24 cells, fenofibrate activated AMPK in a concentration-dependent manner, upregulated FAO enzymes and antioxidants, and induced autophagy, all of which were inhibited by treatment of compound C, an AMPK inhibitor. Fenofibrate-induced autophagy was also significantly blocked by AMPKα1 siRNA but not by PPARα siRNA. Collectively, these results demonstrate that delayed treatment with fenofibrate has a therapeutic effect on HFD-induced kidney injury, at least in part, through the activation of AMPK and induction of subsequent downstream effectors: autophagy, FAO enzymes, and antioxidants.

Effects of the new thiazolidine derivative LPSF/GQ-02 on hepatic lipid metabolism pathways in non-alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is considered the most common manifestation of metabolic syndrome. One of its most important features is the accumulation of triglycerides in the hepatocyte cells. Thiazolidinediones (TZDs) act as insulin sensitizers and are used to treat patients with type 2 diabetes and other conditions that are resistant to insulin, such as hepatic steatosis. Controversially, TZDs are also associated with the development of cardiovascular events and liver problems. For this reason, new therapeutic strategies are necessary to improve liver function in patients with chronic liver diseases. The aim of the present study was to evaluate the effects of LPSF/GQ-02 on the liver lipid metabolism in a murine model of NAFLD. Eighty male LDLR-/- mice were divided into 3 groups: 1-fed with a high-fat diet (HFD); 2-HFD+Pioglitazone (20mg/kg/day); 3-HFD+LPSF/GQ-02 (30mg/kg/day). The experiments lasted 12 weeks and drugs were administered daily by gavage in the final four weeks. The liver was processed for optical microscopy, Oil Red O, immunohistochemistry, immunofluorescence and western blot analysis. LPSF/GQ-02 effectively decreased fat accumulation, increased the hepatic levels of p-AMPK, FoxO1, ATGL, p-ACC and PPARα, and reduced the expression of LXRα, SREBP-1c and ACC. These results suggest that LPSF/GQ-02 acts directly on the hepatic lipid metabolism through the activation of the PPAR-α/AMPK/FoxO1/ATGL lipolytic pathway, and the inhibition of the AMPK/LXR/SREBP-1c/ACC/FAS lipogenic pathway.

Resveratrol and fenofibrate ameliorate fructose-induced nonalcoholic steatohepatitis by modulation of genes expression

AIM: To evaluate the effect of resveratrol, alone and in combination with fenofibrate, on fructose-induced metabolic genes abnormalities in rats.

METHODS: Giving a fructose-enriched diet (FED) to rats for 12 wk was used as a model for inducing hepatic dyslipidemia and insulin resistance. Adult male albino rats (150-200 g) were divided into a control group and a FED group which was subdivided into 4 groups, a control FED, fenofibrate (FENO) (100 mg/kg), resveratrol (RES) (70 mg/kg) and combined treatment (FENO + RES) (half the doses). All treatments were given orally from the 9^th week till the end of experimental period. Body weight, oral glucose tolerance test (OGTT), liver index, glucose, insulin, insulin resistance (HOMA), serum and liver triglycerides (TGs), oxidative stress (liver MDA, GSH and SOD), serum AST, ALT, AST/ALT ratio and tumor necrosis factor-α (TNF-α) were measured. Additionally, hepatic gene expression of suppressor of cytokine signaling-3 (SOCS-3), sterol regulatory element binding protein-1c (SREBP-1c), fatty acid synthase (FAS), malonyl CoA decarboxylase (MCD), transforming growth factor-β1 (TGF-β1) and adipose tissue genes expression of leptin and adiponectin were investigated. Liver sections were taken for histopathological examination and steatosis area were determined.

RESULTS: Rats fed FED showed damaged liver, impairment of glucose tolerance, insulin resistance, oxidative stress and dyslipidemia. As for gene expression, there was a change in favor of dyslipidemia and nonalcoholic steatohepatitis (NASH) development. All treatment regimens showed some benefit in reversing the described deviations. Fructose caused deterioration in hepatic gene expression of SOCS-3, SREBP-1c, FAS, MDA and TGF-β1 and in adipose tissue gene expression of leptin and adiponectin. Fructose showed also an increase in body weight, insulin resistance (OGTT, HOMA), serum and liver TGs, hepatic MDA, serum AST, AST/ALT ratio and TNF-α compared to control. All treatments improved SOCS-3, FAS, MCD, TGF-β1 and leptin genes expression while only RES and FENO + RES groups showed an improvement in SREBP-1c expression. Adiponectin gene expression was improved only by RES. A decrease in body weight, HOMA, liver TGs, AST/ALT ratio and TNF-α were observed in all treatment groups. Liver index was increased in FENO and FENO + RES groups. Serum TGs was improved only by FENO treatment. Liver MDA was improved by RES and FENO + RES treatments. FENO + RES group showed an increase in liver GSH content.

CONCLUSION: When resveratrol was given with half the dose of fenofibrate it improved NASH-related fructose-induced disturbances in gene expression similar to a full dose of fenofibrate.

Fenofibrate increases cardiac autophagy via FGF21/SIRT1 and prevents fibrosis and inflammation in the hearts of Type 1 diabetic mice

Fenofibrate (FF) as a commonly-used lipid-lowering medicine in clinics was examined for its potentially repurposing to prevent the cardiac abnormalities in patients with type 1 diabetes. We demonstrated here that fenofibrate significantly prevented diabetes-induced cardiac dysfunction and remodeling in fibroblast growth factor 21 (FGF21)-dependent manner.

Effects of combined PPAR-γ and PPAR-α agonist therapy on fructose induced NASH in rats: Modulation of gene expression

Peroxisome proliferator-activated receptors (PPARs) gamma and alpha have been shown to play key roles in maintaining glucose and lipid homeostasis by acting as insulin sensitizers and lipid-lowering agents respectively, which would make them potential candidates for the treatment of non-alcoholic steatohepatitis (NASH) characterized by insulin resistance, hyperglycemia, and hypertriglyceridemia. The effects of pioglitazone, a PPAR-γ agonist, and fenofibrate, a PPAR-α agonist, as monotherapy and in combination on the expressions of key genes linked to the development of NASH were studied in rats with fructose-induced NASH. Fructose-enriched diet was given to rats for 12 weeks. Fenofibrate (100mg/kg), pioglitazone (4 mg/kg) and combined treatment with both in half doses were given. Body weight, liver index, insulin resistance indices, triglycerides, oxidative stress markers, AST/ALT ratio and TNF-α were measured. Additionally, hepatic genes expressions of SOCS-3, sterol regulatory element binding protein-1c, fatty acid synthase, malonyl CoA decarboxylase, TGF-β1, and adipose tissue genes expressions of leptin and adiponectin were investigated. The combination of both drugs, in half doses, improved NASH-related disturbances similar to, or even better than, a full dose of fenofibrate alone possibly due to attenuating effects of pioglitazone on expression of genes responsible for insulin resistance, fatty acid synthesis and fibrosis in addition to correcting the balance between leptin and adiponectin. Histopathology confirmed the ability of this combination to decrease steatosis area and to normalize hepatic tissue structure. In Conclusion, dual activation of PPAR-γ and PPAR-α has remarkable effect in ameliorating NASH by modulation of some hepatic and adipose tissue genes expressions.

Doxorubicin toxicity changes myocardial energy metabolism in rats

BACKGROUND

Doxorubicin (DOX) is an antitumor antibiotics used against malignancies. But its toxicity limits the therapy of DOX.

OBJECTIVE

The purpose of this study was to evaluate DOX toxicity and the alteration of energy metabolism after short term and long term treatment.

METHODS

Male Sprague-Dawley rats were randomly assigned to four groups: Short term control group, short term DOX treatment group, long term control group and long term DOX treatment group. In short term treated group, rats were injected with DOX i.p. at a dose of 2.5 mg/kg every 48 h for six equal injections. In long term, treated group, rats were tail-intravenously injected with DOX at a dose of 3 mg/kg once a week for four weeks. At the end of the experiment, histopathological changes, general blood biomarkers, endogenous antioxidant enzymes, cardiac energy metabolism and related mRNA expression of AMPK signal pathway were determined.

RESULTS

DOX induced prominent oxidative stress, a higher mortality rate, histological and ECG changes, obvious cardiac hypertrophy, acute cardiac damage and cardiac energy impairment in short term treatment rats. In long term treatment rats, DOX caused serious nephropathy and systolic dysfunction, terrible cardiac energy impairment, clear alteration of substrate utilization and AMPK signal pathway.

CONCLUSION

DOX treatment can induce different damages after short term and long term treatment. In short term treatment group, rats experienced a terrible mortality rate about 40%, the acute cardiac damage, cardiac energy impairment and an early heart failure which are potential connected with reduction of glucose utilization. In the long term treatment group, serious nephropathy and obvious changes of mRNA expressions of AMPK signal pathway were observed. Meanwhile, the serious cardiac energy impairment and substrate utilization alteration denote an obviously heart failure. This study could be helpful to develop therapy strategies of DOX complications for clinical application.

Effect of High Temperature- and High Pressure-Treated Red Ginseng on Lipolysis and Lipid Oxidation in C2C12 Myotubes

Korean red ginseng (KRG), a highly valuable medicinal herb in oriental societies, has biological activity similar to that of Panax ginseng. Recently, it has been discovered that the biological activities of red ginseng can vary according to heating and steaming processes under different conditions that change the principal components of KRG and result in changes in biological activity. This study evaluated and compared the effects of high temperature- and high pressure-treated red ginseng (HRG) and commercial red ginseng (RG) on β-oxidation in C2C12 myotubes. HRG enhanced the phosphorylation levels of AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC), but RG did not affect the phosphorylation of AMPK in C2C12 myotubes. HRG also promoted the nuclear translocation of forkhead box protein O1 (FoxO1), and the translocation exerted an increase in the protein expression of adipose triglyceride lipase (ATGL). As a consequence, HRG increased the mRNA expression level of carnitine palmitoyltransferase 1 (CPT-1) compared to the control. Taken together, our results indicated that HRG promotes the lipolysis of triglycerides and mitochondrial β-oxidation of fatty acids in C2C12 myotubes, suggesting that alterations to the principal components by high temperature and pressure may positively influence the nutraceutical functions of HRG.

Lipid metabolism and inflammation modulated by Vitamin D in liver of diabetic rats

Background

In recent years, much evidence suggested that vitamin D plays an important role in decreasing the risk of type 2 diabetes. The purpose of this study was to investigate whether 1, 25 (OH) ₂D₃ can modulate inflammation and lipid metabolism in type 2 diabetic rat liver.

Methods

Type 2 diabetes was induced in SD rat with high-fat and high-sugar diets and multiple low-dose streptozotocin. The levels of serum calcium, phosphorus, glucose, TC, TG, AST, ALT and hepatic TG were determined. H & E staining were performed to assess the effects of vitamin D treatment on pathological changes in the liver tissues. Immunohistology, real-time PCR and Western blot were used to evaluate the expressions of NF-κ B, MCP-1, ICAM-1, TGF-β1, PPAR-α and CPT-1.

Results

The administration of 1, 25 (OH) ₂D₃ reduced liver weight. Compared to DM rats, 1, 25 (OH) ₂D₃-treated DM rats had lower liver weight. Moreover, compared to healthy or 1, 25 (OH) ₂D₃-treated DM rats, DM rats had increased hepatic transcription factors (NF-κ B), monocyte chemoattractant protein −1 (MCP-1), intercellular adhesion molecule −1 (ICAM-1), transforming growth factor-β1 (TGF-β1) expressions, but had fewer hepatic PPAR- α and CPT-1 expressions.

Conclusions

1, 25 (OH) ₂D₃ significantly modulated the liver inflammation and lipid metabolism in diabetic rat models, which may be caused by its regulations on hepatic signaling NF-κ B pathway and PPAR- α.

Protective effects of aerobic swimming training on high-fat diet induced nonalcoholic fatty liver disease: regulation of lipid metabolism via PANDER-AKT pathway

This study aimed to investigate the mechanism by which aerobic swimming training prevents high-fat-diet-induced nonalcoholic fatty liver disease (NAFLD). Forty-two male C57BL/6 mice were randomized into normal-diet sedentary (ND; n = 8), ND exercised (n = 8), high-fat diet sedentary (HFD; n = 13), and HFD exercised groups (n = 13). After 2 weeks of training adaptation, the mice were subjected to an aerobic swimming protocol (60 min/day) 5 days/week for 10 weeks. The HFD group exhibited significantly higher mRNA levels of fatty acid transport-, lipogenesis-, and β-oxidation-associated gene expressions than the ND group. PANDER and FOXO1 expressions increased, whereas AKT expression decreased in the HFD group. The aerobic swimming program with the HFD reversed the effects of the HFD on the expressions of thrombospondin-1 receptor, liver fatty acid-binding protein, long-chain fatty-acid elongase-6, Fas cell surface death receptor, and stearoyl-coenzyme A desaturase-1, as well as PANDER, FOXO1, and AKT. In the HFD exercised group, PPARα and AOX expressions were much higher. Our findings suggest that aerobic swimming training can prevent NAFLD via the regulation of fatty acid transport-, lipogenesis-, and β-oxidation-associated genes. In addition, the benefits from aerobic swimming training were achieved partly through the PANDER-AKT-FOXO1 pathway.