Sesamol Alleviates Obesity-Related Hepatic Steatosis via Activating Hepatic PKA Pathway

Hepatic regulator of G protein signaling 14 ameliorates NAFLD through activating cAMP-AMPK signaling by targeting Giα1/3

OBJECTIVE

Nonalcoholic fatty liver disease (NAFLD) is an emerging public health threat as the most common chronic liver disease worldwide. However, there remains no effective medication to improve NAFLD. G protein-coupled receptors (GPCRs) are the most frequently investigated drug targets family. The Regulator of G protein signaling 14 (RGS14), as an essential negative modulator of GPCR signaling, plays important regulatory roles in liver damage and inflammatory responses. However, the role of RGS14 in NAFLD remains largely unclear.

METHODS AND RESULTS

In this study, we found that RGS14 was decreased in hepatocytes in NAFLD individuals in a public database. We employed genetic engineering technique to explore the function of RGS14 in NAFLD. We demonstrated that RGS14 overexpression ameliorated lipid accumulation, inflammatory response and liver fibrosis in hepatocytes in vivo and in vitro. Whereas, hepatocyte specific Rgs14-knockout (Rgs14-HKO) exacerbated high fat high cholesterol diet (HFHC) induced NASH. Further molecular experiments demonstrated that RGS14 depended on GDI activity to attenuate HFHC-feeding NASH. More importantly, RGS14 interacted with Guanine nucleotide-binding protein (Gi) alpha 1 and 3 (Giα1/3, gene named GNAI1/3), promoting the generation of cAMP and then activating the subsequent AMPK pathways. GNAI1/3 knockdown abolished the protective role of RGS14, indicating that RGS14 binding to Giα1/3 was required for prevention against hepatic steatosis.

CONCLUSIONS

RGS14 plays a protective role in the progression of NAFLD. RGS14-Giα1/3 interaction accelerated the production of cAMP and then activated cAMP-AMPK signaling. Targeting RGS14 or modulating the RGS14-Giα1/3 interaction may be a potential strategy for the treatment of NAFLD in the future.

Erchen Decoction alleviates obesity-related hepatic steatosis via modulating gut microbiota-drived butyric acid contents and promoting fatty acid β-oxidation

ETHNOPHARMACOLOGICAL RELEVANCE

Erchen decoction (ECD) is a traditional Chinese medicine formula comprising six distinct herbs and has been documented to possess a protective effect against obesity. The study conducted previously demonstrated that ECD has the potential to effectively modulate the composition of gut microbiota and levels of short-chain fatty acids (SCFAs) in obese rat. However, the regulatory mechanism of ECD on gut microbiota and SCFAs and further improvement of obesity have not been thoroughly explained.

AIM OF THE STUDY

The objective of this study was to examine the therapeutic effect and molecular mechanism of ECD in a rat model of high-fat diet (HFD) feeding.

MATERIALS AND METHODS

Rats with HFD-induced obesity were treated with ECD. Upon completion of the study, serum and liver samples were procured to conduct biochemical, pathological, and Western blotting analyses. The investigation of alterations in the gut microbiota subsequent to ECD treatment was conducted through the utilization of 16S rRNA sequencing. The metabolic alterations in the cecal contents were examined through the utilization of mass spectrometry-ultraperformance liquid chromatography.

RESULTS

ECD treatment improved lipid metabolic disorders and reduced hepatic steatosis in HFD-induced obese rats. Obese rat treated with ECD showed a higher abundance of SCFA-producing bacteria, including Lactobacillus, Bifidobacterium, and Butyricicoccus, and lower abundance of disease-related bacteria, such as Bacteroides, Parabacteroides, and Sediminibacterium. Additionally, ECD caused an increase in total SCFAs levels; in particular, butyric acid was dramatically increased in the HFD group. Rats treated with ECD also exhibited significantly increased butyric acid concentrations in the serum and liver. The subsequent reduction in histone deacetylase 1 expression and increase in acetyl-histone 3-lysine 9 (H3K9ac) levels contributed to the promotion of fatty acid β-oxidation (FAO) in liver by ECD.

CONCLUSION

This study demonstrates that ECD regulates the gut microbiota and promotes butyric acid production to ameliorate obesity-related hepatic steatosis. The mechanism might be related to the promotion of FAO via a butyric acid-mediated increase in H3K9ac levels in the liver.

Sesamol Alleviates High-Fat Diet-Induced Hepatic Insulin Resistance in C57BL/6 J Mice Through AMPK Activation Mediated by Adipose Adiponectin

Sesamol is the major bioactive constituent isolated from sesame seeds and has a variety of bioactivities. However, its role and mechanism in liver insulin resistance remain unknown. The current study was designed to investigate the underlying adipose-liver crosstalk mechanism of sesamol ameliorating hepatic insulin sensitivity. The therapeutic effect of sesamol was evaluated in high-fat diet (HFD)-fed C57BL/6 J mice (100 mg/kg for 8 weeks, XYGW-2021-75) and the mechanism was further explored in HepG2 cells with/without adiponectin and adenosine 5 '-monophosphate-activated protein kinase (AMPK) inhibitor administration. Our in vivo data showed that sesamol reduced hepatic insulin resistance in HFD-induced mice with obesity by modulating protein expression levels of glycogen synthase (GS), phosphoenolpyruvate carboxykinase (PEPCK) and protein kinase B (AKT). Moreover, sesamol not only increased the serum and adipose tissue adiponectin concentrations but also activated the phosphorylation of AMPK in the liver. Furthermore, in vitro studies using recombinant human adiponectin and an AMPK inhibitor revealed that adiponectin and sesamol have a synergic impact on increasing glycogenesis and reducing gluconeogenesis, of which the effects could be attenuated by the AMPK inhibitor. Taken together, our results suggested that sesamol stimulated adiponectin secretion from adipocytes, whereby exhibited a co-effect on activating the downstream signal of hepatic AMPK, resulting in the alleviation of hepatic insulin resistance. The novel findings of sesamol on hepatic effects provides prospective therapeutic approaches to treat insulin resistance.

Theaflavine inhibits hepatic stellate cell activation by modulating the PKA/LKB1/AMPK/GSK3β cascade and subsequently enhancing Nrf2 signaling

Activation of hepatic stellate cells (HSCs) constitutes a crucial etiological factor leading to liver fibrosis. Theaflavine (TF) is a characteristic bioactive compound in fermented tea. Here, we found that TF attenuated the activation of LX-2 HSCs induced by transforming growth factor-β1 (TGF-β1). TF potentiated nuclear factor erythroid 2-related Factor 2 (Nrf2) signaling. Knockdown of Nrf2 abrogated TF-mediated resistance to TGF-β1. Liver kinase B1 (LKB1), AMP-activated kinase (AMPK), and glycogen synthase kinase-3β (GSK3β) are upstream regulators of Nrf2. TF modulated the LKB1/AMPK/GSK3β axis. Inhibition of AMPK or knockdown of LKB1 crippled TF-mediated potentiation of Nrf2. Protein kinase A (PKA) catalyzes LKB1 phosphorylation. In LX-2 cells, TF increased the LKB1/PKA interaction without affecting their contents. Inhibition of PKA abolished TF-mediated potentiation of LKB1/Nrf2 and abrogated the inhibitory effects of TF on their activation. TF also enhanced direct binding between purified catalytic subunit α of PKA (PKA-Cα) and LKB1 proteins in vitro. Molecular docking indicated that TF showed binding activity with both LKB1 and PKA-Cα proteins. In mouse primary HSCs, TF elevated LKB1/PKA-Cα binding, boosted LKB1 phosphorylation, potentiated Nrf2 and suppressed their spontaneous activation. PKA inhibition or LKB1 knockdown eliminated TF-mediated induction of Nrf2 and suppression of HSC activation. Furthermore, TF considerably alleviated CCl4-induced mouse liver fibrosis. In mouse livers, TF increased the LKB1/PKA-Cα interaction, upregulated LKB1 phosphorylation and modulated its downstream AMPK/GSK3β/Nrf2 cascade. Our findings collectively indicated that TF suppresses HSC activation. Mechanistically, TF elevated the LKB1/PKA interaction in HSCs, which increased LKB1 phosphorylation and subsequently modulated the downstream AMPK/GSK3β/Nrf2 axis.

Diosgenin attenuates nonalcoholic hepatic steatosis through the hepatic FXR-SHP-SREBP1C/PPARα/CD36 pathway

Nonalcoholic fatty liver disease (NAFLD) is the most common liver disease worldwide and has no approved treatment. The hepatic farnesoid X receptor (FXR) is one of the most promising therapeutic targets for NAFLD. Diosgenin (DG), a natural compound extracted from Chinese herbal medicine, is very effective in preventing metabolic diseases. Our research aims to determine the effects and molecular mechanisms of DG on NAFLD in vivo and in vitro. The effect of DG on hepatic steatosis was evaluated in Sprague‒Dawley (SD) rats induced by a high-fat diet (HFD) and in HepG2 cells exposed to free fatty acids (FFAs, sodium oleate:sodium palmitate = 2:1). DG treatment efficiently managed hepatic lipid deposition in vivo and in vitro. Mechanistically, DG upregulated the expression of FXR and small heterodimer partner (SHP) and downregulated the expression of genes involved in hepatic de novo lipogenesis (DNL), including sterol regulatory element-binding protein 1C (SREBP1C), acetyl-CoA carboxylase 1 (ACC1), and fatty acid synthase (FASN). Moreover, DG promoted the expression of peroxisome proliferator-activated receptor alpha (PPARα), which is related to fatty acid oxidation. In addition, DG inhibited the expression of the CD36 molecule (CD36) related to fatty acid uptake. However, hepatic FXR silencing weakened the regulatory effects of DG on these genes. Collectively, our data show that DG has a good effect on alleviating nonalcoholic hepatic steatosis via the hepatic FXR-SHP-SREBP1C/PPARα/CD36 pathway. DG promises to be a novel candidate FXR activator that can be utilized to treat NAFLD.

SIRT2 Deficiency Aggravates Diet-Induced Nonalcoholic Fatty Liver Disease through Modulating Gut Microbiota and Metabolites

Non-alcoholic fatty liver disease (NAFLD), characterized by excessive lipid accumulation in hepatocytes, is an increasing global healthcare burden. Sirtuin 2 (SIRT2) functions as a preventive molecule for NAFLD with incompletely clarified regulatory mechanisms. Metabolic changes and gut microbiota imbalance are critical to the pathogenesis of NAFLD. However, their association with SIRT2 in NAFLD progression is still unknown. Here, we report that SIRT2 knockout (KO) mice are susceptible to HFCS (high-fat/high-cholesterol/high-sucrose)-induced obesity and hepatic steatosis accompanied with an aggravated metabolic profile, which indicates SIRT2 deficiency promotes NAFLD-NASH (nonalcoholic steatohepatitis) progression. Under palmitic acid (PA), cholesterol (CHO), and high glucose (Glu) conditions, SIRT2 deficiency promotes lipid deposition and inflammation in cultured cells. Mechanically, SIRT2 deficiency induces serum metabolites alteration including upregulation of L-proline and downregulation of phosphatidylcholines (PC), lysophosphatidylcholine (LPC), and epinephrine. Furthermore, SIRT2 deficiency promotes gut microbiota dysbiosis. The microbiota composition clustered distinctly in SIRT2 KO mice with decreased Bacteroides and Eubacterium, and increased Acetatifactor. In clinical patients, SIRT2 is downregulated in the NALFD patients compared with healthy controls, and is associated with exacerbated progression of normal liver status to NAFLD to NASH in clinical patients. In conclusion, SIRT2 deficiency accelerates HFCS-induced NAFLD-NASH progression by inducing alteration of gut microbiota and changes of metabolites.

Hypolipidemic and Anti-Atherogenic Effects of Sesamol and Possible Mechanisms of Action: A Comprehensive Review

Sesamol is a phenolic lignan isolated from Sesamum indicum seeds and sesame oil. Numerous studies have reported that sesamol exhibits lipid-lowering and anti-atherogenic properties. The lipid-lowering effects of sesamol are evidenced by its effects on serum lipid levels, which have been attributed to its potential for significantly influencing molecular processes involved in fatty acid synthesis and oxidation as well as cholesterol metabolism. In this review, we present a comprehensive summary of the reported hypolipidemic effects of sesamol, observed in several in vivo and in vitro studies. The effects of sesamol on serum lipid profiles are thoroughly addressed and evaluated. Studies highlighting the ability of sesamol to inhibit fatty acid synthesis, stimulate fatty acid oxidation, enhance cholesterol metabolism, and modulate macrophage cholesterol efflux are outlined. Additionally, the possible molecular pathways underlying the cholesterol-lowering effects of sesamol are presented. Findings reveal that the anti-hyperlipidemic effects of sesamol are achieved, at least in part, by targeting liver X receptor α (LXRα), sterol regulatory element binding protein-1 (SREBP-1), and fatty acid synthase (FAS) expression, as well as peroxisome proliferator-activated receptor α (PPARα) and AMP activated protein kinase (AMPK) signaling pathways. A detailed understanding of the molecular mechanisms underlying the anti-hyperlipidemic potential of sesamol is necessary to assess the possibility of utilizing sesamol as an alternative natural therapeutic agent with potent hypolipidemic and anti-atherogenic properties. Research into the optimal sesamol dosage that may bring about such favorable hypolipidemic effects should be further investigated, most importantly in humans, to ensure maximal therapeutic benefit.

Aluminum as a Possible Cause Toward Dyslipidemia

Aluminum, the third most abundant metal present in the earth's crust, is present almost in all daily commodities we use, and exposure to it is unavoidable. The interference of aluminum with various biochemical reactions in the body leads to detrimental health effects, out of which aluminum-induced neurodegeneration is widely studied. However, the effect of aluminum in causing dyslipidemia cannot be neglected. Dyslipidemia is a global health problem, which commences to the cosmic of non-communicable diseases. The interference of aluminum with various iron-dependent enzymatic activities in the tri-carboxylic acid cycle and electron transport chain results in decreased production of mitochondrial adenosine tri-phosphate. This ultimately contributes to oxidative stress and iron-mediated lipid peroxidation. This mitochondrial dysfunction along with modulation of α-ketoglutarate and L-carnitine perturbs lipid metabolism, leading to the atypical accumulation of lipids and dyslipidemia. Respiratory chain disruption because of the accumulation of reduced nicotinamide adenine di-nucleotide as a consequence of oxidative stress and the stimulatory effect of aluminum exposure on glycolysis causes many health issues including fat accumulation, obesity, and other hepatic disorders. One major factor contributing to dyslipidemia and enhanced pro-inflammatory responses is estrogen. Aluminum, being a metalloestrogen, modulates estrogen receptors, and in this world of industrialization and urbanization, we could corner down to metals, particularly aluminum, in the development of dyslipidemia. As per PRISMA guidelines, we did a literature search in four medical databases to give a holistic view of the possible link between aluminum exposure and various biochemical events leading to dyslipidemia.

Natural Foods for the Treatment of Nonalcoholic Fatty Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most common chronic liver diseases worldwide. The etiology of NAFLD is highly heterogeneous, which occurs and develops under the joint action of metabolism, inflammation, genetics, environment, and gut microbiota. At present, the principal therapeutic modalities targeting NAFLD are lifestyle interventions such as weight loss through diet and exercise. At present, there is no established therapy for the treatment of NAFLD, and many therapies are associated with a variety of side effects. A great number of in vitro and in vivo experiments have indicated that there are many natural foods that have therapeutic potential for NAFLD. This review summarizes the natural foods and their mechanisms that were found in recent years, furthermore, provides further information relevant to the treatment of NAFLD.

Research progress of signaling pathways of the natural substances intervene dyslipidemia (Review)

Dyslipidemia is an umbrella term for a range of lipid metabolic disorders in the body. This condition has been widely reported to greatly increase the risk of cardiovascular diseases, threatening human health. In recent years, advances in molecular biology have deepened understanding of the dyslipidemia-related signaling pathways and specific mechanisms underlying dyslipidemia. Signaling pathways possess the ability to transmit an extracellular signal to the inside of the cell, leading to specific biological effects. Lipid metabolism disorders and lipid levels in the blood are frequently affected by aberrant alterations in the dyslipidemia-related signaling pathways. Therefore, further investigations into these pathways are required for the prevention and treatment of dyslipidemia. The present review summarizes the characteristics of six dyslipidemia-associated signaling pathways: Peroxisome proliferator-activated receptor, adenosine monophosphate-activated protein kinase, farnesoid X receptor, forkhead box O, adipocytokine and cyclic adenosine monophosphate signaling pathways. In particular, specific focus was placed on previous experimental studies and reports on the intervention effects of natural substances (compounds from animals, plants, marine organisms and microorganisms) on dyslipidemia.

Sesamol protects the function and structure of rat ovaries against side effects of cyclophosphamide by decreasing oxidative stress and apoptosis

AIM

Chemotherapy with cyclophosphamide can damage ovaries and cause infertility in girls and women. Sesamol is a phenolic antioxidant that can protect various organs from damage. The purpose of this study was to evaluate the effects of sesamol on protecting the function and structure of rat ovaries against the side effects of a chemotherapy model with cyclophosphamide.

METHODS

Twenty-four adult female Wistar rats were randomly divided into three groups: (1) normal group, without any treatment, (2) control group, immediately after receiving cyclophosphamide, 0.5% dimethyl sulfoxide (DMSO) as the solvent of sesamol was intraperitoneally injected for 14 consecutive days, (3) sesamol group, immediately after receiving cyclophosphamide, 50 mg/kg sesamol was intraperitoneally injected for 14 consecutive days. Four weeks after the last injection, superoxide dismutase (SOD) activity and malondialdehyde (MDA) levels in the ovary, anti-Mullerian hormone (AMH) levels in the serum, number of ovarian follicles in different stages, and expression of proteins growth differentiation factor-9 (GDF-9), Bcl-2, and Bax in the ovary were evaluated.

RESULTS

The results of SOD activity and MDA levels in the ovary, AMH levels in the serum, number of ovarian follicles in different stages, and expression of proteins GDF9, Bcl-2, and Bax in the ovary were significantly more favorable in the sesamol group than the control group.

CONCLUSIONS

The results suggest that sesamol may protect function and structure in the rat ovaries against side effects of the chemotherapy model with cyclophosphamide by decreasing oxidative stress and apoptosis in the ovary.

Chronic Intermittent Hypoxia Exposure Alternative to Exercise Alleviates High-Fat-Diet-Induced Obesity and Fatty Liver

Obesity often concurs with nonalcoholic fatty liver disease (NAFLD), both of which are detrimental to human health. Thus far, exercise appears to be an effective treatment approach. However, its effects cannot last long and, moreover, it is difficult to achieve for many obese people. Thus, it is necessary to look into alternative remedies. The present study explored a noninvasive, easy, tolerable physical alternative. In our experiment, C57BL/6 mice were fed with a high-fat diet (HFD) to induce overweight/obesity and were exposed to 10% oxygen for one hour every day. We found that hypoxia exerted protective effects. First, it offset HFD-induced bodyweight gain and insulin resistance. Secondly, hypoxia reversed the HFD-induced enlargement of white and brown adipocytes and fatty liver, and protected liver function. Thirdly, HFD downregulated the expression of genes required for lipolysis and thermogenesis, such as UCP1, ADR3(beta3-adrenergic receptor), CPT1A, ATGL, PPARα, and PGC1α, M2 macrophage markers arginase and CD206 in the liver, and UCP1 and PPARγ in brown fat, while these molecules were upregulated by hypoxia. Furthermore, hypoxia induced the activation of AMPK, an energy sensing enzyme. Fourthly, our results showed that hypoxia increased serum levels of epinephrine. Indeed, the effects of hypoxia on bodyweight, fatty liver, and associated changes in gene expression ever tested were reproduced by injection of epinephrine and prevented by propranolol at varying degrees. Altogether, our data suggest that hypoxia triggers stress responses where epinephrine plays important roles. Therefore, our study sheds light on the hope to use hypoxia to treat the daunting disorders, obesity and NAFLD.

Comparative effects of sesame lignans (sesamin, sesamolin, and sesamol) on oxidative stress and lipid metabolism in steatosis HepG2 cells

Non-alcoholic fatty liver disease (NAFLD) can be attributed to the imbalance between lipogenesis and lipidolysis in the liver. Sesame lignans (sesamin, sesamolin, and sesamol) are unique bioactive compounds responsible for the nutritional function of sesame oils. However, the preventive effects of three lignans on oxidative stress and lipid metabolism in steatosis HepG2 cells have not been compared. In this study, we investigated the role of sesamin, sesamolin, and sesamol on hepatic lipid accumulation and explored the underlying mechanism via a well-established cell model. The results showed that 3 μg/ml of lignans could decrease the TG/TC contents and alleviate cellular oxidative stress, with an order of the lipid-lowering effect as sesamol > sesamin > sesamolin. The lignan-activated AMPK and PPAR signaling pathways enhanced gene and protein expressions related to fatty acid oxidation, cholesterol efflux, and catabolism. Meanwhile, treatment of the steatosis HepG2 cells with sesamin, sesamolin, and sesamol reduced lipid synthesis and cholesterol uptake, thus lowering intracellular lipogenesis in the process of NAFLD. Our data suggested that sesame lignans can attenuate oxidative stress and regulate lipid metabolism in liver cells, which may be potential therapeutic agents for treating the NAFLD. PRACTICAL APPLICATIONS: The present work demonstrated that sesame lignans can be used for dietary supplements or functional additives with excellent lipid-lowering effects. Furthermore, this study supplied potential molecular mechanisms involved in NAFLD treatment process, and also provided nutritional guidelines for sesame oil evaluation and selection.

Sesamol counteracts on metabolic disorders of middle-aged alimentary obese mice through regulating skeletal muscle glucose and lipid metabolism

Background

Globally, obesity is a significant public problem, especially when aging. Sesamol, a phenolic lignan present in sesame seeds, might have a positive effect on high-fat diet (HFD)-induced obesity associated with aging.

Objective

The purpose of current research study was to explore salutary effects and mechanisms of sesamol in treating alimentary obesity and associated metabolic syndrome in middle-aged mice.

Methods

C57BL/6J mice aged 4–6 weeks and 6–8 months were assigned to the young normal diet group, middle-aged normal diet group, middle-aged HFD group, and middle-aged HFD + sesamol group. At the end of experiment, glucose tolerance test and insulin tolerance test were performed; the levels of lipids and oxidative stress-related factors in the serum and skeletal muscle were detected using chemistry reagent kits; lipid accumulation in skeletal muscle was observed by oil red O staining; the expressions of muscular glucose and lipid metabolism associated proteins were measured by Western blotting.

Results

Sesamol decreased the body weight and alleviated obesity-associated metabolism syndrome in middle-aged mice, such as glucose intolerance, insulin resistance, dyslipidemia, and oxidative stress. Moreover, muscular metabolic disorders were attenuated after treatment with sesamol. It increased the expression of glucose transporter type-4 and down-regulated the protein levels of pyruvate dehydrogenase kinase isozyme 4, implying the increase of glucose uptake and oxidation. Meanwhile, sesamol decreased the expression of sterol regulatory element binding protein 1c and up-regulated the phosphorylation of hormone-sensitive lipase and the level of carnitine palmityl transferase 1α, which led to the declined lipogenesis and the increased lipolysis and lipid oxidation. In addition, the SIRT1/AMPK signaling pathway was triggered by sesamol, from which it is understood how sesamol enhances glucose and lipid metabolism.

Conclusions

Sesamol counteracts on metabolic disorders of middle-aged alimentary obese mice through regulating skeletal muscle glucose and lipid metabolism, which might be associated with the stimulation of the SIRT1/AMPK pathway.

Sesamol Reverses Myofiber-Type Conversion in Obese States via Activating the SIRT1/AMPK Signal Pathway

Obesity can evoke changes of skeletal muscle structure and function, which are characterized by the conversion of myofiber from type I to type II, leading to a vicious cycle of metabolic disorders. Reversing the muscle fiber-type conversion in obese states is a novel strategy for treating those with obesity. Sesamol, a food ingredient compound isolated from sesame seeds, exerted potential antiobesity effects. The present research aimed to explore the therapeutic effects of sesamol on obesity-related skeletal muscle-fiber-type conversion and elucidate the underlying molecular mechanisms through utilizing a high-fat-diet-induced obese C57BL/6J mice model and palmitic acid-exposed C2C12 myotubes. The results showed that sesamol attenuated obesity-related metabolic disturbances, elevated exercise endurance of obese mice, and decreased lipid accumulation and insulin resistance in skeletal muscle. After the treatment with sesamol, the muscular mitochondrial content and biogenesis were increased, accompanied by the enzyme activities and myosin heavy-chain isoform changed from type II fiber to type I fiber. Mechanistic studies revealed that the effects of sesamol on reversing skeletal muscle-fiber-type conversion in obese states were associated with the stimulation of the muscular sirtuin 1 (SIRT1)/AMP-activated protein kinase (AMPK) signal pathway, and these effects could be inhibited by a specific inhibitor of SIRT1, EX-527. In conclusion, our research provided novel evidence that sesamol could regulate myofiber-type conversion to treat obesity and obesity-related metabolic disorders by stimulating the muscular SIRT1/AMPK signal pathway.

Decabromodiphenyl ether-induced PRKACA hypermethylation contributed to glycolipid metabolism disorder via regulating PKA/AMPK pathway in rat and L-02 cells

BDE-209 is the most prevalent congener of polybrominated diphenyl ethers and has high bioaccumulation in humans and animals. BDE-209 has been reported to disrupt glycolipid metabolism, but the mechanisms are still unclear. In this study, we found that BDE-209 induced liver tissue injury and hepatotoxicity, increased the glucose and total cholesterol levels in the serum of rats, and increased glucose and triglyceride levels in L-02 cells. BDE-209 exposure changed the PKA, p-PKA, AMPK, p-AMPK, ACC, and FAS expression in rats' liver and L-02 cells. Moreover, BDE-209 induced PRKACA-1 hypermethylation in L-02 cells. AMPK activator (AICAR) inhibited the changes of p-AMPK, ACC, and FAS expression and elevation of glucose and triglyceride levels induced by BDE-209. DNA methylation inhibitor (5-Aza-CdR) reversed BDE-209 induced alters of PKA/AMPK/ACC/FAS signaling pathway. These results demonstrated that BDE-209 could disrupt the glycolipid metabolism by causing PRKACA-1 hypermethylation to regulate the PKA/AMPK signaling pathway in hepatocytes.

Phytochemicals from the Cocoa Shell Modulate Mitochondrial Function, Lipid and Glucose Metabolism in Hepatocytes via Activation of FGF21/ERK, AKT, and mTOR Pathways

The cocoa shell is a by-product that may be revalorized as a source of bioactive compounds to prevent chronic cardiometabolic diseases. This study aimed to investigate the phytochemicals from the cocoa shell as targeted compounds for activating fibroblast growth factor 21 (FGF21) signaling and regulating non-alcoholic fatty liver disease (NAFLD)-related biomarkers linked to oxidative stress, mitochondrial function, and metabolism in hepatocytes. HepG2 cells treated with palmitic acid (PA, 500 µmol L⁻¹) were used in an NAFLD cell model. Phytochemicals from the cocoa shell (50 µmol L⁻¹) and an aqueous extract (CAE, 100 µg mL⁻¹) enhanced ERK1/2 phosphorylation (1.7- to 3.3-fold) and FGF21 release (1.4- to 3.4-fold) via PPARα activation. Oxidative stress markers were reduced though Nrf-2 regulation. Mitochondrial function (mitochondrial respiration and ATP production) was protected by the PGC-1α pathway modulation. Cocoa shell phytochemicals reduced lipid accumulation (53–115%) and fatty acid synthase activity (59–93%) and prompted CPT-1 activity. Glucose uptake and glucokinase activity were enhanced, whereas glucose production and phosphoenolpyruvate carboxykinase activity were diminished. The increase in the phosphorylation of the insulin receptor, AKT, AMPKα, mTOR, and ERK1/2 conduced to the regulation of hepatic mitochondrial function and energy metabolism. For the first time, the cocoa shell phytochemicals are proved to modulate FGF21 signaling. Results demonstrate the in vitro preventive effect of the phytochemicals from the cocoa shell on NAFLD.

N-linoleyltyrosine ameliorates high-fat diet-induced obesity in C57BL/6 mice via cannabinoid receptor regulation

OBJECTIVES

N-linoleyltyrosine (NITyr) showed mild effects in preclinical studies. The research discussed the effect of NITyr on a high-fat diet (HFD) induced obese (DIO) mice, and preliminarily explored its mechanism.

METHODS

The DIO mice were established by feeding an HFD for 12 weeks and subsequently administrated orally with NITyr (30, 60 and 100 mg/kg) for four weeks. The indexes of serum and liver samples were determined by ELISA kit. The pathological status of adipose and liver were detected by HE staining. The factors related to energy and lipid metabolism were measured via western blot.

RESULTS

NITyr at 60 and 100 mg/kg/day suppressed the weight gain without affecting water and food intake. Accordingly, NITyr reduced adipose weight and the area of individual adipocytes and increased the number of adipocytes. Moreover, NITyr didn't affect the appetite-related indexes such as ghrelin, peptide YY and brain-derived neurotrophic factor. Besides, NITyr didn't affect other organ coefficients except for the liver. Correspondingly, NITyr reduced alanine aminotransferase and aspartate aminotransferase levels, yet didn't influence IL-1β and TNF-α levels, and the liver injury. The levels of triacylglycerol (TG), total cholesterol (TC), glucose, insulin, adiponectin and leptin in serum were assessed to evaluate the effect of NITyr on glucose and lipid metabolism. NITyr decreased the levels of TG, TC and glucose, and didn't affect insulin, adiponectin and leptin levels. Meanwhile, NITyr up-regulated p-AMPK and the cannabinoid receptor 2 (CB₂) expressions, and down-regulated PPAR, FAS and cannabinoid receptor 1 (CB₁) expressions.Overall, NITyr suppressed lipid accumulation via improving lipid and glucose metabolism involving CB₁ and CB₂ receptors.

Protective Effects of Sesamol against Liver Oxidative Stress and Inflammation in High-Fat Diet-Induced Hepatic Steatosis

Chronic high-fat diet (HFD) is associated with the onset and progression of hepatic steatosis, and oxidative stress is highly involved in this process. The potential role of sesamol (SEM) against oxidative stress and inflammation at the transcriptional level in a mice model of hepatic steatosis is not known. In this study, we aimed to investigate the scavenging effects of SEM towards reactive oxygen generated by lipid accumulation in the liver of obese mice and to explore the mechanisms of protection. Markers of oxidative stress, vital enzymes involved in stimulating oxidative stress or inflammation, and nuclear transcription of Nrf2 were examined. Our results showed that SEM significantly inhibited the activity of the HFD-induced hepatic enzymes CYP2E1 and NOX2, associated with oxidative stress generation. Additionally, SEM reversed HFD-induced activation of NF-κB, a redox-sensitive transcription factor, and attenuated the expression of hepatic TNF-α, a proinflammatory molecule. Moreover, SEM enhanced HFD-induced hepatic Nrf2 nuclear transcription and increased the levels of its downstream target genes Ho1 and Nqo1, which indicated antiinflammation and antioxidant properties. Our study suggests that chronic HFD led to hepatic steatosis, while SEM exhibited protective effects on the liver by counteracting the oxidative stress and inflammation induced by HFD. The underlying mechanism might involve multiple pathways at the transcriptional level; the antioxidant defense mechanism was in partly mediated by the upregulation of Nrf2.

Sesamol ameliorates hepatic lipid accumulation and oxidative stress in steatosis HepG2 cells via the PPAR signaling pathway

Non-alcoholic fatty liver disease (NAFLD) is a chronic hepatopathy caused by disordered lipid metabolism in the liver. Sesamol, a phenolic compound derived from sesame oil, has been shown to inhibit obesity, hyperlipidemia, and atherosclerosis in previous investigations. However, the preventive effect of sesamol against hepatic steatosis and oxidative stress in NAFLD has not been well-studied. In this work, sesamol was observed to alleviate lipid accumulation and oxidative stress in high oleic acid (300 μM)/cholesterol (25 μM) induced HepG2 cells, thus indicating that sesamol was involved in regulating hepatic lipid metabolism and oxidative injury. Mechanism studies found that the activated peroxisome proliferator-activated receptors (PPAR) signaling pathway by sesamol intervention up-regulated gene and protein expressions related to fatty acid oxidation and cholesterol efflux and catabolism, thus accelerating lipid consumption and reducing intracellular lipid accumulation in the process of NAFLD. These data suggested that sesamol can effectively ameliorate hepatic steatosis and sesamol riched sesamol oil may be a potential agent for finding therapeutic strategies to treat the NAFLD. PRACTICAL APPLICATIONS: Sesamol and sesamol-rich sesame oil have received much attention due to their performance on hepatic lipid regulation. The results of this study indicate that sesamol treatment could ameliorate hepatic steatosis by inhibiting lipid accumulation and oxidative stress, thus demonstrating that sesamol and sesame oil can be used for functional foods and nutraceutical applications in the future. In addition, the present work provides knowledge of the effects of sesamol on NAFLD and involved mechanisms, and further supplies nutritional guidelines for sesame oil consumption.

Sesamol induces cytotoxicity via mitochondrial apoptosis in SCC-25 cells

Sesamol is the main constituent of sesame seed oil and is obtained from Sesamum indicum. Oral squamous cell carcinoma (OSCC) is one of the most common neoplasms affecting the oral cavity. In this study, we investigated the cytotoxic potentials of sesamol on human oral squamous carcinoma (SCC-25) cells. Human oral squamous carcinoma cells were treated with different concentrations (62.5, 125, and 250 μM/mL) of sesamol for 24 h. Cytotoxicity was analyzed by 3- (4, 5- dimethylthiazol -2- yl) -2, 5-diphenyltetrazolium bromide (MTT) assay. Intracellular reactive oxygen species (ROS) expression was investigated by dichloro-dihydro-fluorescein diacetate assay. Apoptosis-related morphology was analyzed by acridine orange/ethidium bromide staining. Caspase-9 expression was analyzed by confocal microscopic double immunofluorescence staining. Mitochondrial apoptosis-related markers are analyzed using qPCR. Sesamol treatment caused a significant cytotoxic effect in OSCC cells. Sesamol-induced cytotoxic effect was associated with intracellular ROS generation. Sesamol treatments induced a significant increase in the early and late apoptotic cells. This treatment also induced caspase-9 expression in OSCC cells. Sesamol treatments caused downregulation of Harvey rat sarcoma viral oncogene homolog (HRAS) expression at protein and gene levels. Sesamol treatment modulates intrinsic apoptotic marker gene expression in OSCC cells. Overall results confirm the anti-cancer potential of sesamol and it seems to be a promising candidate for OSCC.

Sesamol promotes browning of white adipocytes to ameliorate obesity by inducing mitochondrial biogenesis and inhibition mitophagy via β3-AR/PKA signaling pathway

Background

Obesity is defined as an imbalance between energy intake and expenditure, and it is a serious risk factor of non-communicable diseases. Recently many studies have shown that promoting browning of white adipose tissue (WAT) to increase energy consumption has a great therapeutic potential for obesity. Sesamol, a lignan from sesame oil, had shown potential beneficial functions on obesity treatment.

Objective

In this study, we used C57BL/6J mice and 3T3-L1 adipocytes to investigate the effects and the fundamental mechanisms of sesamol in enhancing the browning of white adipocytes to ameliorate obesity.

Methods

Sixteen-week-old C57BL/6J male mice were fed high-fat diet (HFD) for 8 weeks to establish the obesity models. Half of the obese mice were administered with sesamol (100 mg/kg body weight [b.w.]/day [d] by gavage for another 8 weeks. Triacylglycerol (TG) and total cholesterol assay kits were used to quantify serum TG and total cholesterol (TC). Oil red O staining was used to detect lipid droplet in vitro. Mito-Tracker Green was used to detect the mitochondrial content. Quantitative reverse transcription-polymerase chain reaction (RT-PCR) was used to detect the levels of beige-specific genes. Immunoblotting was used to detect the proteins involved in beige adipocytes formation.

Results

Sesamol decreased the content of body fat and suppressed lipid accumulation in HFD-induced obese mice. In addition, sesamol significantly upregulated uncoupling protein-1 (UCP1) protein in adipose tissue. Further research found that sesamol also significantly activated the browning program in mature 3T3-L1 adipocytes, manifested by the increase in beige-specific genes and proteins. Moreover, sesamol greatly increased mitochondrial biogenesis, as proved by the upregulated protein levels of mitochondrial biogenesis, and the inhibition of the proteins associated with mitophagy. Furthermore, β3-adrenergic receptor (β3-AR), protein kinase A-C (PKA-C) and Phospho-protein kinase A (p-PKA) substrate were elevated by sesamol, and these effects were abolished by the pretreatment of antagonists β3-AR.

Conclusion

Sesamol promoted browning of white adipocytes by inducing mitochondrial biogenesis and inhibiting mitophagy through the β3-AR/PKA pathway. This preclinical data promised the potential to consider sesamol as a metabolic modulator of HFD-induced obesity.