A high-fish-oil diet prevents adiposity and modulates white adipose tissue inflammation pathways in mice

Fish oil supplementation during pregnancy decreases liver endocannabinoid system and lipogenic markers in newborn rats exposed to maternal high-fat diet

PURPOSE

Maternal high-fat diet (HF) programs obesity, metabolic dysfunction-associated steatotic liver disease (MASLD), hypertriglyceridemia, and hyperglycemia associated with increased endocannabinoid system (ECS) in the liver of adult male rat offspring. We hypothesized that maternal HF would induce sex specific ECS changes in the liver of newborn rats, prior to obesity onset, and maternal fish oil (FO) supplementation would reprogram the ECS and lipid metabolism markers preventing liver triglycerides (TG) accumulation.

METHODS

Female rats received a control (CT) (10.9% fat) or HF (28.7% fat) diet 8 weeks prior to mating and during pregnancy. A subgroup of HF dams received 3% FO supplementation in the HF diet (35.4% fat) during pregnancy (HFFO). Serum hormones and liver TG, ECS, lipid metabolism, oxidative stress and autophagy markers were assessed in male and female newborn offspring.

RESULTS

Maternal HF diet increased liver cannabinoid receptor 1 (CB1) in males and decreased CB2 in females, with no effect on liver TG. Maternal FO supplementation reduced liver CB1 regardless of the offspring sex, but reduced TG liver content only in females. FO reduced the liver content of the endocannabinoid anandamide in males, and the content of 2-arachidonoylglycerol in both sexes. Maternal HF increased lipogenic and decreased lipid oxidation markers, and FO induced the opposite regulation in the liver of offspring.

CONCLUSION

Prenatal HF and FO differentially modulate liver ECS in the offspring before obesity and MASLD development. These results suggest that maternal nutrition at critical stages of development can modulate the offspring's ECS, predisposing or preventing the onset of metabolic diseases.

Delta-6 desaturase (Fads2) deficiency alters triacylglycerol/fatty acid cycling in murine white adipose tissue

The Δ-6 desaturase (D6D) enzyme is not only critical for the synthesis of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from α-linolenic acid (ALA), but recent evidence suggests that it also plays a role in adipocyte lipid metabolism and body weight; however, the mechanisms remain largely unexplored. The goal of this study was to investigate if a D6D deficiency would inhibit triacylglycerol storage and alter lipolytic and lipogenic pathways in mouse white adipose tissue (WAT) depots due to a disruption in EPA and DHA production. Male C57BL/6J D6D knockout (KO) and wild-type (WT) mice were fed either a 7% w/w lard or flax (ALA rich) diet for 21 weeks. Energy expenditure, physical activity, and substrate utilization were measured with metabolic caging. Inguinal and epididymal WAT depots were analyzed for changes in tissue weight, fatty acid composition, adipocyte size, and markers of lipogenesis, lipolysis, and insulin signaling. KO mice had lower body weight, higher serum nonesterified fatty acids, smaller WAT depots, and reduced adipocyte size compared to WT mice without altered food intake, energy expenditure, or physical activity, regardless of the diet. Markers of lipogenesis and lipolysis were more highly expressed in KO mice compared to WT mice in both depots, regardless of the diet. These changes were concomitant with lower basal insulin signaling in WAT. Collectively, a D6D deficiency alters triacylglycerol/fatty acid cycling in WAT by promoting lipolysis and reducing fatty acid re-esterification, which may be partially attributed to a reduction in WAT insulin signaling.

Dietary n-3 and n-6 polyunsaturated fatty acids differentially modulate the adiponectin and leptinmediated major signaling pathways in visceral and subcutaneous white adipose tissue in high fat diet induced obesity in Wistar rats

Obesity is a chronic metabolic disease that involves excessive accumulation of fat in white adipose tissue (WAT). Apart from storing excess fats, WAT also serves as an important endocrine organ secreting adipocytokines such as adiponectin and leptin. Adiponectin and leptin bind to their transmembrane receptors adiponectin receptor 1 (AdipoR1)/adiponectin receptor 2 (AdipoR2) and Ob-R, respectively, and mediate their effect on metabolism by regulating multiple downstream targets. Dietary fat is considered the main culprit behind obesity development. Numerous preclinical studies have highlighted role of essential polyunsaturated fatty acids (PUFAs), particularly n-3 PUFAs, in prevention of obesity. Despite emerging data, there still is no clear understanding of the mechanism of action of n-3 PUFAs and n-6 PUFAs on adipose tissue function in two functionally and anatomically different depots of WAT: visceral and subcutaneous. We designed this study using a high fat diet (HFD) fed rodent model of obesity to test our hypothesis that n-3 and n-6 PUFAs possibly differentially modulate adipokine secretion and downstream metabolic pathways such as peroxisome proliferator-activated receptor-γ (PPAR-γ), protein kinase B (AKT)-forkhead box O1 (FOXO1), and Janus kinase-signal transducer and activator of transcription in obesity. The results of the current study showed that n-3 PUFAs upregulate the expression of AdipoR1/R2 and ameliorate the effects of HFD by modulating adipogenesis via PPAR-γ and by improving glucose tolerance and lipid metabolism via AKT-FOXO1 axis in fish oil fed rats. However, n-6 PUFAs did not show any remarkable change compared with HFD fed animals. Our study highlights that n-3 PUFAs modulate expression of various targets in adiponectin and leptin signaling cascade, bringing about an overall reduction in obesity and improvement in adipose tissue function in HFD induced obesity.

Adipose tissue plays a major role in retinoic acid-mediated metabolic homoeostasis

Retinoic acid (RA), a bioactive metabolite of vitamin A, has shown therapeutic effects in liver disease, and its effect in improving non-alcoholic fatty liver disease (NAFLD) is associated with the inhibition of adipogenesis in the white adipose tissue (WAT) and fatty acid oxidation induction in the liver. However, the major target organ of RA is unknown. We performed chronic administration of RA in high-fat diet (HFD)-induced NAFLD mice. Further, hepatic and adipose cells were used to study the direct effect of RA on lipid metabolism. In addition, qRT-PCR was performed to examine differential gene expression in mouse adipose tissue. RA administration ameliorated NAFLD in HFD-induced obese mice and increased mouse energy expenditure. Although RA had therapeutic effects on liver histology and lipid accumulation, it did not directly affect lipid metabolism in HepG2 cells. In contrast, RA reduced the weight of several adipose tissues and improved lipid accumulation in OP9 cells. In addition, RA upregulated genes responsible for fatty acid oxidation and thermogenesis in three different WATs. Our work suggests that the liver may not be the main target organ of RA during NAFLD treatment. WAT browning induced by RA may be the primary contributor towards the amelioration of NAFLD in HFD-induced obese mice.

Semaglutide (GLP-1 receptor agonist) stimulates browning on subcutaneous fat adipocytes and mitigates inflammation and endoplasmic reticulum stress in visceral fat adipocytes of obese mice

Semaglutide (GLP-1 agonist) was approved for treating obesity. Although the effects on weight loss and metabolism are known, the responses of adipocytes to semaglutide are yet limited. C57BL/6 male mice (n = 20/group) were fed a control diet (C) or a high-fat (HF) diet for 16 weeks and then separated into four groups (n = 10/group) for an additional four weeks: C, C diet and semaglutide, HF, and HF diet and semaglutide. Epididymal white adipose tissue (eWAT) and subcutaneous white adipose tissue (sWAT) fat pads were studied with biochemistry, immunohistochemistry/fluorescence, stereology, and reverse transcription-quantitative polymerase chain reaction. In obese mice, semaglutide reduced the fat pad masses (eWAT, -55%; sWAT, -40%), plasmatic cytokines, and proinflammatory gene expressions: tumor necrosis factor-alpha (-60%); interleukin (IL)-6 (-55%); IL-1 beta (-40%); monocyte chemoattractant protein-1 (-90%); and leptin (-80%). Semaglutide also lessened endoplasmic reticulum (ER) stress genes of activating transcription factor-4 (-85%), CCAAT enhancer-binding protein homologous protein (-55%), and growth arrest and DNA damage-inducible gene 45 (-45%). The obese mice's adipocyte hypertrophy and macrophage infiltration were equally reduced by semaglutide. Semaglutide enhanced multiloculation and uncoupled protein 1 (UCP1) labeling in obese mice: peroxisome proliferator-activated receptor-alpha (+560%) and gamma (+150%), fibronectin type III domain-containing protein 5 (+215%), peroxisome proliferator-activated receptor-alpha coactivator (+110%), nuclear respiratory factor 1 (+260%), and mitochondrial transcription factor A (+120%). Semaglutide also increased thermogenetic gene expressions for the browning phenotype maintenance: beta-3 adrenergic receptor (+520%), PR domain containing 16 (+90%), and Ucp1 (+110%). In conclusion, semaglutide showed significant beneficial effects beyond weight loss, directly on fat pads and adipocytes of obese mice, remarkably anti-inflammatory, and reduced adipocyte size and ER stress. Besides, semaglutide activated adipocyte browning, improving UCP1, mitochondrial biogenesis, and thermogenic marker expressions help weight loss.

α-Linolenic acid rich-chia seed modulates visceral adipose tissue collagen deposition, lipolytic enzymes expression, insulin signaling and GLUT-4 levels in a diet-induced adiposity rodent model

Given obesity and its associated metabolic disorders have reached epidemic proportions, the study of therapeutic strategies targeting white adipose tissue (WAT) are of main research interest. We previously shown that α-linolenic acid-rich chia seed was able to ameliorate a wide range of metabolic disorders including body fat accretion in sucrose-rich diet (SRD)-fed rats, an experimental model of visceral adiposity and insulin resistance. However, the mechanisms involved are not fully clarified. The aim of this study was to evaluate the effect of chia seed administration upon WAT remodeling and key enzymes that controls lipolysis, insulin signaling (tAKT, pAKT), and GLUT-4 levels in different visceral fat pad depots (epididymal -eWAT- and retroperitoneal -rWAT- adipose tissues) of SRD-fed rats. Results showed that chia seed reduces adipocytes hypertrophy, the increased lipid content and collagen deposition in both WAT. These changes were accompanied by a significant reduction of HSL and ATGL protein levels in eWAT and HSL protein levels in rWAT. Moreover, chia seed restored the altered expression pattern of the pAKT observed in SRD-fed rats, and modulated GLUT-4 levels. Chia seed could be a dietary intervention of great relevance with potential beneficial effects in the management of body fat excess and WAT function.

6-Gingerol exerts a protective effect against hypoxic injury through the p38/Nrf2/HO-1 and p38/NF-κB pathway in H9c2 cells

Ginger, one of the most widely consumed condiment for various foods and beverages, has many pharmacological effects. 6-gingerol, a naturally occurring phenol, is one of the major pungent constituents of ginger. The purpose of this study was to characterize the effect of 6-gingerol on the p38/Nrf2/HO-1 and p38/NF-κB signaling pathway, as a possible means of combating hypoxia-related oxidative stress. H9c2 cells were chemically induced with CoCl₂ to mimic hypoxia-associated cellular damage. Cardiomyocyte injury was assessed by lactate dehydrogenase and creatine kinase. Reactive oxygen species production was assessed by 2',7'-dichlorodihydrofluorescein diacetate. The antioxidative property of 6-gingerol was measured by estimating the activities of superoxide dismutase, catalase, glutathione and glutathione disulfide. Apoptosis was detected by flow cytometry after Annexin V-FITC-propidium iodide double staining. Western blotting was used to evaluate levels of p-p38, p38, cytoplasm p65, nuclear p65, total p65, nuclear Nrf2, total Nrf2, Keap1, HIF-1α, and HO-1. 6-gingerol was able to counter hypoxia-induced cardiomyocyte injury as evidenced by inhibiting the levels of oxidative stress indexes and increasing the percentage of apoptosis. Furthermore, 6-gingerol was able to down-regulate p-p38/p38, nuclear p65, total p65 and Keap1 expression induced by CoCl₂ stimulation and increased cytoplasm p65, nuclear Nrf2, total Nrf2, HO-1, and HIF-1α expression. However, treatment with specific Nrf2 inhibitor blunted the activation of Nrf2 signaling and removed the protective effects of 6-gingerol. These experiments provide evidence that 6-gingerol exerts cytoprotective effects, which may be associated with the regulation of oxidative stress and apoptosis, potentially through activating the Nrf2 pathway and inhibiting the p38/NF-κB pathways.

Regulation of Sirt1 on energy metabolism and immune response in rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease. Synovial hyperplasia and persistent inflammation serve as its typical pathological manifestations, which ultimately lead to joint destruction and function loss. Both clinical observations and metabolomics studies have revealed the prevalence of metabolic disorders in RA. In inflammatory immune microenvironments, energy metabolism is profoundly changed. Increasingly evidences suggest that this abnormality is involved in the occurrence and development of RA-related inflammation. Unsurprisingly, many energy metabolism sensors have been confirmed with immunoregulatory properties. As a representative, silent information regulator type 1 (Sirt1) controls many aspects of immune cells, such as cell lifespan, polarization, and secretion by functioning as a transcriptional regulator. Because of the profound clinical implication, researches on Sirt1 in the regulation of energy metabolism and immune functions under RA conditions have gradually gained momentum. This signaling balances glycolysis, lipid metabolism and insulin secretion orchestrating with other metabolism sensors, and consequently affects immune milieu through a so-called metabolism-immune feedback mechanism. This article reviews the involvement of Sirt1 in RA by discussing its impacts on energy metabolism and immune functions, and specially highlights the potential of Sirt1-targeting anti-rheumatic regimens. It also provides a theoretical basis for clarifying the mystery about the high incidence of metabolic complications in RA patients and identifying new anti-rheumatic reagents.

Efficacy of krill oil versus fish oil on obesity-related parameters and lipid gene expression in rats: randomized controlled study

Backround

This study aimed to determine the effects of LC n-3 PUFA supplementation on the prevention and treatment of obesity and obesity-related diseases, and to compare the efficiency of different LC n-3 PUFA sources via biochemical and genetic mechanisms in rats.

Methods

Male Wistar rats were randomized into four study groups, and fed with a standard diet, High Fat Diet (HFD), HFD+%2.5 Fish Oil (FO-HFD) or HFD+%2.5 Krill Oil (KO-HFD) for eight weeks. Food consumption, weight gain, serum glucose, insulin, ghrelin and leptin concentrations, lipid profile, liver fatty acid composition, and FADS1 and FADS2 mRNA gene expression levels were measured.

Results

Weight gain in each HFD group was significantly higher than control group (p < 0.001), without any differences among them (p < 0.05). LC n-3 PUFAs modified lipid profile, but not glucose tolerance. Serum leptin levels were significantly higher in HFD groups than in the control group, however, no difference in serum ghrelin levels was observed among the groups. Liver n-3 fatty acid desaturation activity was higher (p = 0.74), and liver total lipid content was lower (p = 0.86) in KO-HFD compared to FO-HFD. FADS1 gene expression was highest in the HFD group (p < 0.001) while FADS2 gene expression was highest in the FO-HFD group (p < 0.001).

Conclusion

LC n-3 PUFAs, especially krill oil, had moderate effects on lipid profile, but limited effects on obesity related parameters, suggesting different effects of different sources on gene expression levels. Further randomized controlled trials are needed to determine the efficacy of different LC n-3 PUFA sources in the prevention and treatment of obesity in humans.

Effects of a Fish Oil Rich in Docosahexaenoic Acid on Cardiometabolic Risk Factors and Oxidative Stress in Healthy Rats

Omega-3 polyunsaturated fatty acids are associated with a lower risk of cardiometabolic diseases. However, docosahexaenoic acid (DHA) is easily oxidized, leading to cellular damage. The present study examined the effects of an increased concentration of DHA in fish oil (80% of total fatty acids) on cardiometabolic risk factors and oxidative stress compared to coconut oil, soybean oil, and fish oil containing eicosapentaenoic acid (EPA) and DHA in a balanced ratio. Forty healthy male Sprague-Dawley rats were supplemented with corresponding oil for 10 weeks. Supplementation with the fish oil containing 80% DHA decreased plasma fat, plasma total cholesterol and muscle fat compared to the coconut oil and the soybean oil. Increasing concentrations of DHA induced incorporation of DHA and EPA in cell membranes and tissues along with a decrease in ω-6 arachidonic acid. The increase in DHA promoted lipid peroxidation, protein carbonylation and antioxidant response. Taken together, the increased concentration of DHA in fish oil reduced fat accumulation compared to the coconut oil and the soybean oil. This benefit was accompanied by high lipid peroxidation and subsequent protein carbonylation in plasma and in liver. In our healthy framework, the slightly higher carbonylation found after receiving fish oil containing 80% DHA might be a protecting mechanism, which fit with the general improvement of antioxidant defense observed in those rats.

Gut Microbiota in Adipose Tissue Dysfunction Induced Cardiovascular Disease: Role as a Metabolic Organ

The gut microbiome has emerged as a key regulator of host metabolism. Accumulating evidence has indicated that the gut microbiota is involved in the development of various human diseases. This association relies on the structure and metabolites of the gut microbiota. The gut microbiota metabolizes the diet ingested by the host into a series of metabolites, including short chain fatty acids, secondary bile acids, trimethylamine N-oxide, and branched-chain amino acids, which affects the physiological processes of the host by activating numerous signaling pathways. In this review, we first summarize the various mechanisms through which the gut microbiota influences adipose tissue dysfunction and metabolic processes that subsequently cause cardiovascular diseases, highlighting the complex interactions between gut microbes, their metabolites, and the metabolic activity of the host. Furthermore, we investigated the current status of clinical therapies for adipose tissue dysfunction directed at the gut microbiota. Finally, we discuss the challenges that remain to be addressed before this field of research can be translated to everyday clinical practice.

High-Fat Diet Induces Inflammation of Meibomian Gland

Purpose

To determine if a high-fat diet (HFD) induces meibomian gland (MG) inflammation in mice.

Methods

Male C57BL/6J mice were fed a standard diet (SD), HFD, or HFD supplemented with the peroxisome proliferator-activated receptor gamma (PPAR-γ) agonist rosiglitazone for various durations. Body weight, blood lipid levels, and eyelid changes were monitored at regular intervals. MG sections were subjected to hematoxylin and eosin staining, LipidTox staining, TUNEL assay, and immunostaining. Quantitative RT-PCR and western blot analyses were performed to detect relative gene expression and signaling pathway activation in MGs.

Results

MG acinus accumulated more lipids in the mice fed the HFD. Periglandular CD45-positive and F4/80-positive cell infiltration were more evident in the HFD mice, and they were accompanied by upregulation of inflammation-related cytokines. PPAR-γ downregulation accompanied activation of the mitogen-activated protein kinase (MAPK) and nuclear factor kappa B (NF-κB) signaling pathways in the HFD mice. There was increased acini cell apoptosis and mitochondria damage in mice fed the HFD. MG inflammation was ameliorated following a shift to the standard diet and rosiglitazone treatment in the mice fed the HFD.

Conclusions

HFD-induced declines in PPAR-γ expression and MAPK and NF-κB signaling pathway activation resulted in MG inflammation and dysfunction in mice.

Emerging role of protein kinases in diabetes mellitus: From mechanism to therapy

Diabetes mellitus has emerged as a severe burden on the medical health system across the globe. Presently, around 422 million people are suffering from diabetes which is speculated to be expanded to about 600 million by 2035. Patients with type 2 diabetes are at increased risk of developing detrimental metabolic and cardiovascular complications. The scientific understanding of this chronic disease and its underlying root cause is not yet fully unraveled. Protein kinases are well known to regulate almost every cellular process through phosphorylation of target protein in diverse signaling pathways. The important role of several protein kinases including AMP-activated protein kinase, IκB kinase and protein kinase C have been well demonstrated in various animal models. They modulate glucose tolerance, inflammation and insulin resistance in the cells via acting on diverse downstream targets and signaling pathways. Thus, modulating the activity of potential human kinases which are significantly involved in diabetes by targeting with small molecule inhibitors could be an attractive therapeutic strategy to tackle diabetes. In this chapter, we have discussed the potential role of protein kinases in glucose metabolism and insulin sensitivity, and in the pathogenesis of diabetes mellitus. Furthermore, the small molecules reported in the literature that can be potentially used for the treatment of diabetes have been discussed in detail.

Marine n-3 polyunsaturated fatty acids: Efficacy on inflammatory-based disorders

Inflammation is a physiological response to injury, stimulating tissue repair and regeneration. However, the presence of peculiar individual conditions can negatively perturb the resolution phase eventually leading to a state of low-grade systemic chronic inflammation, characterized by tissue and organ damages and increased susceptibility to non-communicable disease. Marine n-3 polyunsaturated fatty acids (n-3 PUFAs), mainly eicosapentaenoic (EPA) and docosahexaenoic acid (DHA), are able to influence many aspects of this process. Experiments performed in various animal models of obesity, Alzheimer's disease and multiple sclerosis have demonstrated that n-3 PUFAs can modulate the basic mechanisms as well as the disease progression. This review describes the available data from experimental studies to the clinical trials.

Analysis of the intricate effects of polyunsaturated fatty acids and polyphenols on inflammatory pathways in health and disease

Prevention and treatment of non-communicable diseases (NCDs), including cardiovascular disease, diabetes, obesity, cancer, Alzheimer's and Parkinson's disease, arthritis, non-alcoholic fatty liver disease and various infectious diseases; lately most notably COVID-19 have been in the front line of research worldwide. Although targeting different organs, these pathologies have common biochemical impairments - redox disparity and, prominently, dysregulation of the inflammatory pathways. Research data have shown that diet components like polyphenols, poly-unsaturated fatty acids (PUFAs), fibres as well as lifestyle (fasting, physical exercise) are important factors influencing signalling pathways with a significant potential to improve metabolic homeostasis and immune cells' functions. In the present manuscript we have reviewed scientific data from recent publications regarding the beneficial cellular and molecular effects induced by dietary plant products, mainly polyphenolic compounds and PUFAs, and summarize the clinical outcomes expected from these types of interventions, in a search for effective long-term approaches to improve the immune system response.

Fish oil and corn oil induced differential effect on beiging of visceral and subcutaneous white adipose tissue in high-fat-diet-induced obesity

Obesity is characterised by excessive accumulation of fat in white adipose tissue (WAT) which is compartmentalised into two anatomically and functionally diverse depots - visceral and subcutaneous. Advice to substitute essential polyunsaturated fatty acids (PUFAs) for saturated fatty acids is a cornerstone of various obesity management strategies. Despite an array of reports on the role of essential PUFAs on obesity, there still exists a lacuna on their mode of action in distinct depots i.e. visceral (VWAT) and subcutaneous (SWAT). The present study aimed to evaluate the effect of fish oil and corn oil on VWAT and SWAT in high-fat-diet-induced rodent model of obesity. Fish oil (FO) supplementation positively ameliorated the effects of HFD by regulating the anthropometrical and serum lipid parameters. FO led to an overall reduction in fat mass in both depots while specifically inducing beiging of adipocytes in SWAT as indicated by increased UCP1 and PGC1α. We also observed an upregulation of AMPKα and ACC1/2 phosphorylation on FO supplementation in SWAT suggesting a role of AMPK-PGC1α-UCP1 axis in beiging of adipose tissue. On the other hand, corn oil supplementation did not show any improvements in adipose tissue metabolism in both the depots of adipose tissue. The results were analysed using one-way ANOVA followed by Tukey's test in Graphpad Prism 5.0. Combined together our results suggest that n-3 PUFAs exert their anti-obesity effect by regulating adipokine secretion and inducing beiging of SWAT, hence increasing energy expenditure via thermogenic upregulation.

High dietary lipid level alters the growth, hepatic metabolism enzyme, and anti-oxidative capacity in juvenile largemouth bass Micropterus salmoides

The present study was conducted to investigate the effects of high dietary lipid levels on growth, metabolism, antioxidant capacity, and immune responses of largemouth bass. Fish (initial body weight 13.38 ± 0.11 g) were fed three isonitrogenous semi-purified diets containing 5%, 10%, and 20% lipid, respectively. The results indicated that fish fed 10% lipid diet showed significantly better final body weight, specific growth rate (SGR), protein efficiency ratio (PER), and feed conversion ratio (FCR) compared with that fed 5% lipid diet. Meanwhile, fish fed 20% lipid diet had a significantly higher viscera ratio (VR), hepatosomatic index (HSI), intraperitoneal fat ratio (IPF), and liver lipid content than those fed the other diets. Higher alanine aminotransferase (ALT) and aspartate transaminase (AST) activities, total cholesterol (TC), triglyceride (TG), free fatty acids (FFA), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) contents, and LDL-C/HDL-C value in plasma were recorded in fish fed 20% lipid diet, while higher insulin contents were obtained in fish fed 5% lipid diet. In addition, the highest carnitine palmitoyltransferase I (CPT1), AMP-activated protein kinase (AMPK), fructose-1,6-bisphosphatase (FBPase), and phosphoenolpyruvate carboxykinase (PEPCK) activities in the liver were also observed in fish fed 20% lipid diet. However, fish fed 20% lipid diet had a significantly lower superoxide dismutase (SOD) and catalase (CAT) activities and higher MDA contents in liver than those fed the other diets. The higher nitric oxide (NO) contents and inducible nitric oxide synthase (iNOS) activity in liver were recorded in fish fed 10% lipid diet. Moreover, the alkaline phosphatase (ALP), inducible nitric oxide synthase (iNOS) and lysozyme activities, and nitric oxide (NO) contents in plasma were higher in fish fed the 10% diets than the other groups. In conclusion, high dietary lipid levels could suppress growth performance and liver anti-oxidative capacity, and reduce immune responses of largemouth bass.

Aerobic exercise modulates cardiac NAD(P)H oxidase and the NRF2/KEAP1 pathway in a mouse model of chronic fructose consumption

The present study investigated the effects of exercise on the cardiac nuclear factor (erythroid-derived 2) factor 2 (NRF2)/Kelch-like ECH-associated protein 1 (KEAP1) pathway in an experimental model of chronic fructose consumption. Male C57BL/6 mice were assigned to Control, Fructose (20% fructose in drinking water), Exercise (treadmill exercise at moderate intensity), and Fructose + Exercise groups ( n = 10). After 12 wk, the energy intake and body weight in the groups were similar. Maximum exercise testing, resting energy expenditure, resting oxygen consumption, and carbon dioxide production increased in the exercise groups (Exercise and Fructose + Exercise vs. Control and Fructose groups, P < 0.05). Chronic fructose intake induced circulating hypercholesterolemia, hypertriglyceridemia, and hyperleptinemia and increased white adipose tissue depots, with no changes in blood pressure. This metabolic environment increased circulating IL-6, IL-1β, IL-10, cardiac hypertrophy, and cardiac NF-κB-p65 and TNF-α expression, which were reduced by exercise ( P < 0.05). Cardiac ANG II type 1 receptor and NAD(P)H oxidase 2 (NOX2) were increased by fructose intake and exercise decreased this response ( P < 0.05). Exercise increased the cardiac expression of the NRF2-to-KEAP1 ratio and phase II antioxidants in fructose-fed mice ( P < 0.05). NOX4, glutathione reductase, and catalase protein expression were similar between the groups. These findings suggest that exercise confers modulatory cardiac effects, improving antioxidant defenses through the NRF2/KEAP1 pathway and decreasing oxidative stress, representing a potential nonpharmacological approach to protect against fructose-induced cardiometabolic diseases.

NEW & NOTEWORTHY This is the first study to evaluate the cardiac modulation of NAD(P)H oxidase (NOX), the NRF2/Kelch-like ECH-associated protein 1 pathway (KEAP), and the thioredoxin (TRX1) system through exercise in the presence of moderate fructose intake. We demonstrated a novel mechanism by which exercise improves cardiac antioxidant defenses in an experimental model of chronic fructose intake, which involves NRF2-to-KEAP1 ratio modulation, enhancing the local phase II antioxidants hemoxygenase-1, thioredoxin reductase (TXNRD1), and peroxiredoxin1B (PDRX1), and inhibiting cardiac NOX2 overexpression.

Omega-3 polyunsaturated fatty acids have beneficial effects on visceral fat in diet-induced obesity model

This study evaluated the effects of omega-3 polyunsaturated fatty acids (PUFAs) on oxidative stress and energy metabolism parameters in the visceral fat of a high-fat-diet induced obesity model. Energy intake, body mass, and visceral fat mass were also evaluated. Male Swiss mice received either a control diet (control group) or a high-fat diet (obese group) for 6 weeks. After this period, the groups were divided into control + saline, control + omega-3, obese + saline, and obese + omega-3, and to these groups 400 mg·(kg body mass)-1·day-1 of fish oil (or saline) was administered orally, for 4 weeks. Energy intake and body mass were monitored throughout the experiment. In the 10th week, the animals were euthanized and the visceral fat (mesenteric) was removed. Treatment with omega-3 PUFAs did not affect energy intake or body mass, but it did reduced visceral fat mass. In visceral fat, omega-3 PUFAs reduced oxidative damage and alleviated changes to the antioxidant defense system and the Krebs cycle. The mitochondrial respiratory chain was neither altered by obesity nor by omega-3 PUFAs. In conclusion, omega-3 PUFAs have beneficial effects on the visceral fat of obese mice because they mitigate changes caused by the consumption of a high-fat diet.

Macronutrients and the Adipose-Liver Axis in Obesity and Fatty Liver

Macronutrient metabolism is a highly orchestrated process, with adipose tissue and liver each playing central roles in nutrient uptake, processing, transport, and storage. These 2 tissues form an important metabolic circuit, particularly as it relates to lipids as the primary storage form of excess energy. The function of the circuit is influenced by many factors, including the quantity and type of nutrients consumed and their impact on the overall health of the tissues. In this review we begin with a brief summary of the homeostatic disposition of lipids between adipose tissue and liver and how these processes can become dysregulated in obesity. We then explore how specific dietary nutrients and nutrient combinations can exert unique influences on the liver-adipose tissue axis.

GPR120 protects lipotoxicity-induced pancreatic β-cell dysfunction through regulation of PDX1 expression and inhibition of islet inflammation

G-protein coupled receptor 120 (GPR120) has been shown to act as an omega-3 unsaturated fatty acid sensor and is involved in insulin secretion. However, the underlying mechanism in pancreatic β cells remains unclear. To explore the potential link between GPR120 and β-cell function, its agonists docosahexaenoic acid (DHA) and GSK137647A were used in palmitic acid (PA)-induced pancreatic β-cell dysfunction, coupled with GPR120 knockdown (KD) in MIN6 cells and GPR120 knockout (KO) mice to identify the underlying signaling pathways. In vitro and ex vivo treatments of MIN6 cells and islets isolated from wild-type (WT) mice with DHA and GSK137647A restored pancreatic duodenal homeobox-1 (PDX1) expression levels and β-cell function via inhibiting PA-induced elevation of proinflammatory chemokines and activation of nuclear factor κB, c-Jun amino (N)-terminal kinases1/2 and p38MAPK signaling pathways. On the contrary, these GPR120 agonism-mediated protective effects were abolished in GPR120 KD cells and islets isolated from GPR120 KO mice. Furthermore, GPR120 KO mice displayed glucose intolerance and insulin resistance relative to WT littermates, and β-cell functional related genes were decreased while inflammation was exacerbated in islets with increased macrophages in pancreas from GPR120 KO mice. DHA and GSK137647A supplementation ameliorated glucose tolerance and insulin sensitivity, as well as improved Pdx1 expression and islet inflammation in diet-induced obese WT mice, but not in GPR120 KO mice. These findings indicate that GPR120 activation is protective against lipotoxicity-induced pancreatic β-cell dysfunction, via the mediation of PDX1 expression and inhibition of islet inflammation, and that GPR120 activation may serve as a preventative and therapeutic target for obesity and diabetes.

Omega-3 Fatty Acids Attenuate Brain Alterations in High-Fat Diet-Induced Obesity Model

This study evaluated the effects of omega-3 on inflammation, oxidative stress, and energy metabolism parameters in the brain of mice subjected to high-fat diet-induced obesity model. Body weight and visceral fat weight were evaluated as well. Male Swiss mice were divided into control (purified low-fat diet) and obese (purified high-fat diet). After 6 weeks, the groups were divided into control + saline, control + omega-3, obese + saline, and obese + OMEGA-3. Fish oil (400 mg/kg/day) or saline solution was administrated orally, during 4 weeks. When the experiment completed 10 weeks, the animals were euthanized and the brain and visceral fat were removed. The brain structures (hypothalamus, hippocampus, prefrontal cortex, and striatum) were isolated. Treatment with omega-3 had no effect on body weight, but reduced the visceral fat. Obese animals showed increased inflammation, increased oxidative damage, decreased antioxidant enzymes activity and levels, changes in the Krebs cycle enzyme activities, and inhibition of mitochondrial respiratory chain complexes in the brain structures. Omega-3 treatment partially reversed the changes in the inflammatory and in the oxidative damage parameters and attenuated the alterations in the antioxidant defense and in the energy metabolism (Krebs cycle and mitochondrial respiratory chain). Omega-3 had a beneficial effect on the brain of obese animals, as it partially reversed the changes caused by the consumption of a high-fat diet and consequent obesity. Our results support studies that indicate omega-3 may contribute to obesity treatment.

n-3 PUFA and obesity: from peripheral tissues to the central nervous system

The current paradigms of prevention and treatment are unable to curb obesity rates, which indicates the need to explore alternative therapeutic approaches. Obesity leads to several damages to the body and is an important risk factor for a number of other chronic diseases. Furthermore, despite the first alterations in obesity being observed and reported in peripheral tissues, studies indicate that obesity can also cause brain damage. Obesity leads to a chronic low-grade inflammatory state, and the therapeutic manipulation of inflammation can be explored. In this context, the use of n-3 PUFA (especially in the form of fish oil, rich in EPA and DHA) may be an interesting strategy, as this substance is known by its anti-inflammatory effect and numerous benefits to the body, such as reduction of TAG, cardiac arrhythmias, blood pressure and platelet aggregation, and has shown potential to help treat obesity. Thereby, the aim of this narrative review was to summarise the literature related to n-3 PUFA use in obesity treatment. First, the review provides a brief description of the obesity pathophysiology, including alterations that occur in peripheral tissues and at the central nervous system. In the sequence, we describe what are n-3 PUFA, their sources and their general effects. Finally, we explore the main topic linking obesity and n-3 PUFA. Animal and human studies were included and alterations on the whole organism were described (peripheral tissues and brain).

Effect of Notoginsenoside R1 on autologous adipose graft in rats

Autologous fat particle transplantation has been widely used by surgeons. The present study evaluated the effect of Notoginsenoside R1 (NR1) treatment on rat autologous fat graft, along with the quality and retention rates. Male Sprague‑Dawley rats (n=60) received fat particle auto‑transplantation from the left abdominal cavity into lateral dorsum. A total of 14 days after surgery, NR1 in different doses (50, 100 and 200 mg/kg/day) was injected into rats, following which blood and fat graft samples were harvested at days 7, 14 and 28. Assessments were carried out by hematoxylin and eosin staining, western blotting, ELISA and immunohistochemistry (IHC). The survival rate of fat grafts was increased in three experimental groups, as detected by weight measurement. Histological scoring demonstrated that there were significant differences in tissue integrity between the 100 mg/kg/day group and the other 3 groups. hepatocyte growth factor, vascular endothelial growth factor, fibroblast growth factor, angiotensin and S100 levels in the 100 mg/kg/day NR1 group was increased compared with the other 2 treatment groups; however, all 3 treatment groups demonstrated increased expression of these proteins compared with the control group. Additionally, cluster of differentiation (CD)68 exhibited negative expression and CD31 showed weakly positive expression in all three experiments, as assessed by IHC. In conclusion, 100 mg/kg/day NR1 may potentially promote the retention rate and enhance the quality of autologous fat grafts via increasing vascularity in the recipient site. These results implicate NR1 as a therapeutic strategy for the improvement of outcome following fat graft surgery.

Comparison of Methods for Analyzing Human Adipose Tissue Macrophage Content

OBJECTIVE

The relationship between inflammation, obesity, and adverse metabolic conditions is associated with adipose tissue macrophages (ATM). This study compared the measurements of human ATM using flow cytometry, immunohistochemistry (IHC), and real-time polymerase chain reaction (RT-PCR) of ATM markers.

METHODS

A new software program (AMCounter) was evaluated to help measure ATM using IHC, and this was compared to flow cytometry and RT-PCR.

RESULTS

IHC had good intraindividual reproducibility for total (CD68), proinflammatory (CD14), and anti-inflammatory (CD206) ATM. The AMCounter improved interreader agreement and was more time efficient. Flow cytometry had acceptable intraindividual reproducibility for the percentage of CD68⁺ cells that were CD14⁺ or CD206⁺ , but not for ATMs per gram of tissue. ATMs per gram of tissue was much greater using IHC than flow cytometry. The flow cytometry and IHC measures of ATM from the same biopsies were not correlated. There were statistically significant correlations between RT-PCR CD68 and IHC CD68, CD14, and CD206 ATMs per 100 adipocytes. Also of interest were statistically significant correlations between RT-PCR CD68 and IHC CD68, CD14, and adipose flow cytometry measures of CD68⁺ , CD68⁺ /CD14⁺ , and CD68⁺ /CD206⁺ ATMs per gram of tissue.

CONCLUSIONS

The AMCounter software helps provide reproducible and efficient measures of IHC ATMs. Flow cytometry, IHC, and RT-PCR measures of adipose inflammation provide somewhat different information.

Modulation of the gut microbiota by the mixture of fish oil and krill oil in high-fat diet-induced obesity mice

Previous studies confirmed that dietary supplements of fish oil and krill oil can alleviate obesity in mice, but the underlying mechanism remains unclear. This study aims to discern whether oil treatment change the structure of the gut microbiota during the obesity alleviation. The ICR mice received high-fat diet (HFD) continuously for 12 weeks after two weeks of acclimatization with a standard chow diet, and the mice fed with a standard chow diet were used as the control. In the groups that received HFD with oil supplementation, the weight gains were attenuated and the liver index, total cholesterol, triglyceride and low-density lipoprotein cholesterol were reduced stepwise compared with the HFD group, and the overall structure of the gut microbiota, which was modulated in the HFD group, was shifted toward the structure found in the control group. Moreover, eighty-two altered operational taxonomic units responsive to oil treatment were identified and nineteen of them differing in one or more parameters associated with obesity. In conclusion, this study confirmed the effect of oil treatment on obesity alleviation, as well as on the microbiota structure alterations. We proposed that further researches are needed to elucidate the causal relationship between obesity alleviation and gut microbiota modulation.

Eicosapentaenoic acid (EPA) vs. Docosahexaenoic acid (DHA): Effects in epididymal white adipose tissue of mice fed a high-fructose diet

BACKGROUND

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been demonstrated to be beneficial for many diseases, including those associated with the metabolic syndrome (e.g. insulin resistance and hypertension). Nevertheless, not only their actions are not entirely understood, but also their only effects were not yet elucidated. Therefore, we aimed to compare the effects of EPA and DHA, alone or in combination, on the epididymal white adipose tissue (WAT) metabolism in mice fed a high-fructose diet.

METHODS

3-mo-old C57Bl/6 mice were fed a control diet (C) or a high-fructose diet (HFru). After three weeks on the diets, the HFru group was subdivided into four new groups for another five weeks: HFru, HFru+EPA, HFru+DHA, and HFru-EPA+DHA (n=10/group). Besides evaluating biometric and metabolic parameters of the animals, we measured the adipocyte area and performed molecular analyses (inflammation and lipolysis) in the epididymal WAT.

RESULTS

The HFru group showed adipocyte hypertrophy, inflammation, and uncontrolled lipolysis. The treated animals showed a reversion of adipocyte hypertrophy, inhibition of inflammation with activation of anti-inflammatory mediators, and regularization of lipolysis. Overall, the beneficial effects were more marked with DHA than EPA.

CONCLUSION

Although the whole-body metabolic effects were similar between EPA and DHA, DHA appeared to be the central actor in WAT metabolism, modulating pro and anti-inflammatory pathways and alleviating adipocytes abnormalities. Therefore, when considering fructose-induced adverse effects in WAT, the most prominent actions were observed with DHA.

Effect of 6-gingerol on AMPK- NF-κB axis in high fat diet fed rats

OBJECTIVES

Adenosine monophosphate (AMP)-activated protein kinase (AMPK) plays a central role in metabolic homeostasis and regulation of inflammatory responses through attenuation of nuclear factor kappa-B (NF-κB), Thus AMPK may be a promising pharmacologic target for the treatment of various chronic inflammatory diseases. We examined the effect of 6-gingerol, an active ingredient of ginger on AMPK-NF-κB pathway in high fat diet (HFD) rats in comparison to fish oil.

METHODS

Protein levels of AMPK-α1 and phosphorylated AMPK-α1 were measured by western blot while Sirtuin 6 (Sirt-6), resistin and P65 were estimated by RT-PCR, TNF-α was determined by ELISA, FFAs were estimated chemically as well as the enzymatic determination of the metabolic parameters.

RESULTS

6-Gingerol substantially enhanced phosphorylated AMPK-α1 more than fish oil and reduced the P65 via upregulation of Sirt-6 and downregulation of resistin, and resulted in attenuation of the inflammatory molecules P65, FFAs and TNF-α more than fish oil treated groups but in an insignificant statistical manner, those effects were accompanied by a substantial hypoglycemic effect.

CONCLUSION

Gingerol treatment effectively modulated the state of inflammatory privilege in HFD group and the metabolic disorders via targeting the AMPK-NF-κB pathway, through an increment in the SIRT-6 and substantial decrement in resistin levels.

TRPV1 activation counters diet-induced obesity through sirtuin-1 activation and PRDM-16 deacetylation in brown adipose tissue

Background/Objective

An imbalance between energy intake and expenditure leads to obesity. Increasing metabolism and thermogenesis in brown adipose tissue (BAT) can help in overcoming obesity. Here, we investigated the effect of activation of transient receptor potential vanilloid subfamily 1 (TRPV1) in the upregulation of thermogenic proteins in BAT to counter diet-induced obesity.

Subjects/Methods

We investigated the effect of dietary supplementation of capsaicin (TRPV1 agonist) on the expression of metabolically important thermogenic proteins in BAT of wild type and TRPV1^−/− mice that received either a normal chow or high fat (± capsaicin; TRPV1 activator) diet by immunoblotting. We measured the metabolic activity, respiratory quotient and BAT lipolysis.

Results

CAP antagonized high fat diet (HFD)-induced obesity without decreasing energy intake in mice. HFD suppressed TRPV1 expression and activity in BAT and CAP countered this effect. HFD feeding caused glucose intolerance, hypercholesterolemia and decreased the plasma concentration of glucagon like peptide-1 and CAP countered these effects. HFD suppressed the expression of metabolically important thermogenic genes, ucp-1, bmp8b, sirtuin 1, pgc-1α and prdm-16 in BAT and CAP prevented this effect. CAP increased the phosphorylation of sirtuin 1 and induced an interaction between PPARγ with PRDM-16. Further, CAP treatment, in vitro, decreased the acetylation of PRDM-16, which was antagonized by inhibition of TRPV1 by capsazepine, chelation of intracellular Ca²⁺ by cell permeable BAPTA-AM or the inhibition of SIRT-1 by EX 527. Further, CAP supplementation, post HFD, promoted weight loss and enhanced the respiratory exchange ratio. CAP did not have any effect in TRPV1^−/− mice.

Conclusions

Our data show that activation of TRPV1 in BAT enhances the expression of SIRT-1, which facilitates the deacetylation and interaction of PPARγ and PRDM-16. These data suggest that TRPV1 activation is a novel strategy to counter diet-induced obesity by enhancing metabolism and energy expenditure.

Fish oil diet modulates epididymal and inguinal adipocyte metabolism in mice

We aimed to investigate the impact of different high-fat diets containing fish oil on adiposity and white adipose tissue (WAT) function in mice, comparing the effects on epididymal (eWAT) and subcutaneous (sWAT) depots. For this, we used C57BL/6 male mice fed four types of diets for eight weeks: standard chow (SC), high-fat lard (HF-L), high-fat lard plus fish oil (HF-L + FO), and high-fat fish oil (HF-FO). The HF-L group had a greater body mass (BM) gain, insulin resistance, increased gene expression related to lipogenesis (CD36, aP2, SREBP1c, and FAS), decreased gene expression of perilipin in both eWAT and sWAT, and reduced expression of genes related to beta-oxidation (CPT-1a) and to mitochondrial biogenesis (PGC1alpha, NRF1, and TFAM) in eWAT and sWAT. On the other hand, the HF-L + FO and HF-FO groups showed a smaller BM gain and adiposity, and normalization of insulin resistance and lipogenic genes in both eWAT and sWAT. These animals also showed decreased perilipin gene expression and elevated expression of beta-oxidation and mitochondrial biogenesis genes in eWAT and sWAT. 'Beige' adipocytes were identified in sWAT of the HF-FO animals. In conclusion, fish oil intake has anti-obesity effects through modulation of both eWAT and sWAT metabolism in mice and is relevant in diminishing the BM gain, adiposity, and insulin resistance even in combination with a high-fat lard diet in mice.

Protein kinases: mechanisms and downstream targets in inflammation-mediated obesity and insulin resistance

Obesity-induced low-grade inflammation (metaflammation) impairs insulin receptor signaling. This has been implicated in the development of insulin resistance. Insulin signaling in the target tissues is mediated by stress kinases such as p38 mitogen-activated protein kinase, c-Jun NH2-terminal kinase, inhibitor of NF-kB kinase complex β (IKKβ), AMP-activated protein kinase, protein kinase C, Rho-associated coiled-coil containing protein kinase, and RNA-activated protein kinase. Most of these kinases phosphorylate several key regulators in glucose homeostasis. The phosphorylation of serine residues in the insulin receptor and IRS-1 molecule results in diminished enzymatic activity in the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. This has been one of the key mechanisms observed in the tissues that are implicated in insulin resistance especially in type 2 diabetes mellitus (T2-DM). Identifying the specific protein kinases involved in obesity-induced chronic inflammation may help in developing the targeted drug therapies to minimize the insulin resistance. This review is focused on the protein kinases involved in the inflammatory cascade and molecular mechanisms and their downstream targets with special reference to obesity-induced T2-DM.

Adipocyte in vascular wall can induce the rupture of abdominal aortic aneurysm

Abdominal aortic aneurysm (AAA) is a vascular disease involving the gradual dilation of the abdominal aorta. It has been reported that development of AAA is associated with inflammation of the vascular wall; however, the mechanism of AAA rupture is not fully understood. In this study, we investigated the mechanism underlying AAA rupture using a hypoperfusion-induced animal model. We found that the administration of triolein increased the AAA rupture rate in the animal model and that the number of adipocytes was increased in ruptured vascular walls compared to non-ruptured walls. In the ruptured group, macrophage infiltration and the protein levels of matrix metalloproteinases 2 and 9 were increased in the areas around adipocytes, while collagen-positive areas were decreased in the areas with adipocytes compared to those without adipocytes. The administration of fish oil, which suppresses adipocyte hypertrophy, decreased the number and size of adipocytes, as well as decreased the risk of AAA rupture ratio by 0.23 compared to the triolein administered group. In human AAA samples, the amount of triglyceride in the adventitia was correlated with the diameter of the AAA. These results suggest that AAA rupture is related to the abnormal appearance of adipocytes in the vascular wall.

Sunflower Oil but Not Fish Oil Resembles Positive Effects of Virgin Olive Oil on Aged Pancreas after Life-Long Coenzyme Q Addition

An adequate pancreatic structure is necessary for optimal organ function. Structural changes are critical in the development of age-related pancreatic disorders. In this context, it has been reported that different pancreatic compartments from rats were affected according to the fat composition consumed. Since there is a close relationship between mitochondria, oxidative stress and aging, an experimental approach has been developed to gain more insight into this process in the pancreas. A low dosage of coenzyme Q was administered life-long in rats in order to try to prevent pancreatic aging-related alterations associated to some dietary fat sources. According to that, three groups of rats were fed normocaloric diets containing Coenzyme Q (CoQ) for two years, where virgin olive, sunflower, or fish oil was included as unique fat source. Pancreatic samples for microscopy and blood samples were collected at the moment of euthanasia. The main finding is that CoQ supplementation gives different results according to fat used in diet. When sunflower oil was the main fat in the diet, CoQ supplementation seems to improve endocrine pancreas structure and in particular β-cell mass resembling positive effects of virgin olive oil. Conversely, CoQ intake does not seem to improve the structural alterations of exocrine compartment previously observed in fish oil fed rats. Therefore CoQ may improve pancreatic alterations associated to the chronic intake of some dietary fat sources.