Fish oil prevents changes induced by a high-fat diet on metabolism and adipokine secretion in mice subcutaneous and visceral adipocytes

Amelioration of obesity induction by a high-fat diet and related inflammation by Phasa fish (Setipinna phasa) oil in BALB/c mice

We have extracted and characterized Phasa fish (Setipinna phasa) oil for the first time to evaluate the anti-obesity and related anti-inflammatory effects on obese mice. Inbred male albino BALB/c mice were segregated into three categories: control (C), Obese control group (OC), and Phasa fish oil treated group (TX). To establish the potentiality of Setipinna phasa oil for its anti-obesity and anti-inflammatory properties, it was extracted and characterized using GC-MS method. To evaluate the anti-obesity effect, different parameters were considered, such as body weight, lipid composition, obesity, and obesity associated inflammation. The physicochemical characteristics of Phasa fish oil revealed that the oil quality was good because acid value, peroxide value, p-anisidine value, Totox value, refractive index, and saponification value were within the standard value range. The GC-MS study explored the presence of fatty acids beneficial to health such as Hexadec-9-enoic acid; Octadec-11-enoic acid; EPA, DHA, Methyl Linolenate, etc. The application of Setipinna phasa oil on the treated mice group acutely lowered body weight and serum lipid profile compared to the obese group. In connection with this, leptin, FAS, and pro-inflammatory cytokines TNF-α genes expression were downregulated in the treated group compared to the obese group. The Phasa oil treated group had an elevated expression of PPAR-α, adiponectin, LPL gene, and anti-inflammatory markers IL-10 and IL-1Ra compared to the obese group. This study suggests that Phasa fish oil, enriched with essential fatty acid, might be used as an anti-obesity and anti-inflammatory supplement.

Can dietary proteins selectively reduce either the visceral or subcutaneous adipose tissues?

There is a considerable appeal for interventions that can selectively reduce either the visceral or subcutaneous white adipose tissues in humans and other species because of their associated impact on outcomes related to metabolic health. Here, we reviewed the data related to the specificity of five interventions to affect the two depots in humans and rodents. The interventions relate to the use of dietary proteins, monounsaturated fatty acids, polyunsaturated fatty acids, calorie restriction, or bariatric surgery. The available data show that calorie restriction and bariatric surgery reduce both visceral and subcutaneous tissues, whereas there is no consistency in the effect of monounsaturated or polyunsaturated fatty acids. Dietary proteins, more specifically, whey proteins show efficacy to reduce one or both depots based on how the proteins interact with other macronutrients in the diet. We provide evidence that this specificity is related to changes in the composition and the functional potential of the gut microbiota and the resulting metabolites produced by these microorganisms. The effect of the sex of the host is also discussed. This knowledge may help to develop nutritional approaches to deplete either the visceral or subcutaneous adipose tissues and improve metabolic health in humans and other species.

Different ratios of DHA/EPA reverses insulin resistance by improving adipocyte dysfunction and lipid disorders in HFD-induced IR mice

Objective: Insulin resistance (IR) is linked to the development of diabetes, non-alcoholic fatty liver disease (NAFLD), and cardiovascular disease (CVDs). Docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) from fish oils (FOs) were used to investigate their potential in high-fat diet (HFD)-induced IR mice under different ratios. Methods: A total of 84 male C57BL/6J (6 weeks old) mice were fed with HFD containing 45% kcal from fat for 16 weeks to establish the IR model. The IR mice were then fed with HFD or HFD + 4% DHA/EPA with different ratios (3 : 1, 1.5 : 1, 1 : 1, 1 : 1.5, 1 : 3, respectively) for another 12 weeks. During the experiment, the CON group (n = 12) was set to feed with a basic diet containing 10% kcal from fat. Results: HFD feeding for 16 weeks reduced insulin sensitivity and accelerated hypertrophy of white adipose tissue (WAT). Different ratios of DHA/EPA except for 1 : 1 decreased the HOMA-IR index, average area of adipocytes, and serum MDA, but increased the protein expression of PI3K. All ratios of DHA/EPA increased the protein expression of IRS-1, GLUT4, and adiponectin. Moreover, dietary DHA/EPA changed serum fatty acid (FA) composition by increasing the serum concentration of n-3 PUFAs. DHA/EPA supplements also improved serum lipid profiles (TG/TC/LDL-c/HDL-c, FFA) and reduced the hepatic steatosis area. Conclusions: The results indicate that an appropriate higher ratio of DHA (1.5 : 1) in DHA/EPA supplementation is recommended for IR prevention.

High-fat diet decreases H3K27ac in mice adipose-derived stromal cells

OBJECTIVE

The study goal was to analyze the effects of a high-fat diet (HFD) on the histone 3 lysine 27 (H3K27) posttranscriptional modifications and the expression of histone-modifying enzymes in adipose-derived stromal cells (ASCs) from white adipose tissue (WAT).

METHODS

Male C57BL/6J mice received control or HFD for 12 weeks. The ASCs were isolated from subcutaneous and visceral (epididymal) WAT, cultivated, and evaluated for expression of H3K27 trimethylation (H3K27me3) and H3K27 acetylation (H3K27ac) by Western blot. The transcription of histone-modifying enzymes was analyzed by real-time polymerase chain reaction.

RESULTS

When compared with control, HFD ASCs showed a decrease in H3K27ac enrichment in subcutaneous and visceral WAT and ATP-citrate lyase expression in subcutaneous WAT. Curiously, the expression of CREB-binding protein was increased in visceral ASCs from HFD-fed mice.

CONCLUSIONS

These results show that an HFD significantly reduces acetylation of H3K27 in ASCs and the expression of ATP-citrate lyase in subcutaneous ASCs, suggesting that, in this fat depot, the H3K27ac reduction could be partly due to lower acetyl-coenzyme A availability. H3K27ac is an epigenetic mark responsible for increasing the transcription rate and its reduction can have an important impact on ASC proliferation and differentiation potential.

Palmitoleic Acid Acts on Adipose-Derived Stromal Cells and Promotes Anti-Hypertrophic and Anti-Inflammatory Effects in Obese Mice

Adipose tissue (AT) secretes adipokines, modulators of low-grade chronic inflammation in obesity. Molecules that induce the emergence of new and functional adipocytes in AT can alleviate or prevent inflammatory and metabolic disorders. The objective of this study was to investigate the role of palmitoleic acid (n7) in 3T3-L1 and primary pre-adipocyte differentiation and AT inflammation. C57BL/6j mice were submitted to a control or high-fat diet (HFD) for 8 weeks, and treated with n7 for 4 weeks. Mice consuming a HFD presented an increase in body weight, epididymal (Epi) fat mass, and Epi adipocytes size. N7 treatment attenuated the body weight gain and completely prevented the hypertrophy of Epi adipocytes, but not the increment in Epi mass induced by the HFD, suggesting a greater adipocytes hyperplasia in animals treated with n7. It was agreed that n7 increased 3T3-L1 proliferation and differentiation, as well as the expression of genes involved in adipogenesis, such as Cebpa, Pparg, aP2, Perilipin, and Scl2a4. Furthermore, n7 decreased the inflammatory cytokines Mcp1, Tnfa, Il6, Cxcl10, and Nos2 genes in Epi vascular stromal cells, but not in the whole AT. These findings show that n7 exerts anti-hypertrophic effects in adipocytes which influence the surrounding cells by attenuating the overexpression of pro-inflammatory cytokines triggered by a HFD.

Early overnutrition in male mice negates metabolic benefits of a diet high in monounsaturated and omega-3 fats

Overconsumption of saturated fats promotes obesity and type 2 diabetes. Excess weight gain in early life may be particularly detrimental by promoting earlier diabetes onset and potentially by adversely affecting normal development. In the present study we investigated the effects of dietary fat composition on early overnutrition-induced body weight and glucose regulation in Swiss Webster mice, which show susceptibility to high-fat diet-induced diabetes. We compared glucose homeostasis between a high-fat lard-based (HFL) diet, high in saturated fats, and a high-fat olive oil/fish oil-based (HFO) diet, high in monounsaturated and omega-3 fats. We hypothesized that the healthier fat profile of the latter diet would improve early overnutrition-induced glucose dysregulation. However, early overnutrition HFO pups gained more weight and adiposity and had higher diabetes incidence compared to HFL. In contrast, control pups had less weight gain, adiposity, and lower diabetes incidence. Plasma metabolomics revealed reductions in various phosphatidylcholine species in early overnutrition HFO mice as well as with diabetes. These findings suggest that early overnutrition may negate any beneficial effects of a high-fat diet that favours monounsaturated and omega-3 fats over saturated fats. Thus, quantity, quality, and timing of fat intake throughout life should be considered with respect to metabolic health outcomes.

Retinal bioavailability and functional effects of a synthetic very-long-chain polyunsaturated fatty acid in mice

Rare, nondietary very-long-chain polyunsaturated fatty acids (VLC-PUFAs) are uniquely found in the retina and a few other vertebrate tissues. These special fatty acids play a clinically significant role in retinal degeneration and development, but their physiological and interventional research has been hampered because pure VLC-PUFAs are scarce. We hypothesize that if Stargardt-3 or age-related macular degeneration patients were to consume an adequate amount of VLC-PUFAs that could be directly used in the retina, it may be possible to bypass the steps of lipid elongation mediated by the retina's ELOVL4 enzyme and to delay or prevent degeneration. We report the synthesis of a VLC-PUFA (32:6 n-3) in sufficient quantity to study its bioavailability and functional benefits in the mouse retina. We acutely and chronically gavage fed wild-type mice and Elovl4 rod-cone conditional knockout mice this synthetic VLC-PUFA to understand its bioavailability and its role in visual function. VLC-PUFA-fed wild-type and Elovl4 conditional knockout mice show a significant increase in retinal VLC-PUFA levels in comparison to controls. The VLC-PUFA-fed mice also had improvement in the animals' visual acuity and electroretinography measurements. Further studies with synthetic VLC-PUFAs will continue to expand our understanding of the physiological roles of these unique retinal lipids, particularly with respect to their potential utility for the treatment and prevention of retinal degenerative diseases.

Protective effects of a unique combination of nutritionally active ingredients on risk factors and gene expression associated with atherosclerosis in C57BL/6J mice fed a high fat diet

Atherosclerosis, an inflammatory disorder of the vasculature and the underlying cause of cardiovascular disease, is responsible for one in three global deaths. Consumption of active food ingredients such as omega-3 polyunsaturated fatty acids, flavanols and phytosterols has many beneficial effects on cardiovascular disease. However, their combined actions on the risk factors for atherosclerosis remains poorly understood. We have previously shown that a formulation containing each of these active components at physiologically relevant doses modulated several monocyte/macrophage processes associated with atherosclerosis in vitro, including inhibition of cytokine-induced pro-inflammatory gene expression, chemokine-driven monocyte migration, expression of M1 phenotype markers, and promotion of cholesterol efflux. The objectives of the present study were to investigate whether the protective actions of the formulation extended in vivo and to delineate the potential underlying mechanisms. The formulation produced several favourable changes, including higher plasma levels of HDL and reduced levels of macrophages and myeloid-derived suppressor cells in the bone marrow. The mRNA expression of liver-X-receptor-α, peroxisome proliferator-activated receptor-γ and superoxide dismutase-1 was induced in the liver and that of interferon-γ and the chemokine (C-X-C motif) ligand 1 decreased, thereby suggesting the potential mechanisms for many beneficial effects. Other changes were also observed such as increased plasma levels of triglycerides and lipid peroxidation that may reflect potential activation of brown fat. This study provides new insights into the protective actions and the potential underlying mechanisms of the formulation in vivo, particularly in relation to risk factors together with changes in systemic inflammation and hepatic lipid alterations associated with atherosclerosis and metabolic syndrome, and supports further assessments in human trials.

n-3 PUFAs protect against adiposity and fatty liver by promoting browning in postnatally overfed male rats: a role for NRG4

Early-life nutrition plays an important role in regulating adult metabolism. This study evaluated the effects of early nutrition during the suckling and postweaning periods on expression of the adipocytokine Neuregulin 4 (Nrg4) and its relationship with nonalcoholic fatty liver disease (NAFLD) in adulthood. In vivo, male rats were adjusted to litter sizes of three (small litter, SL) or ten (normal litter, NL) on postnatal day 3. Pups were fed control chow (NL and SL groups) or a high-fat diet (NL-HF and SL-HF groups), and SL pups specifically were fed a fish oil diet rich in n-3 polyunsaturated fatty acids (n-3 PUFAs) (SL-FO group), from postnatal weeks 3 to 13. The results demonstrated that postnatal overnutrition increased weight, hepatic de novo lipogenesis (DNL) gene expression and NAFLD and decreased body temperature and Nrg4, Ucp1 and Pgc1a mRNA expression in adipose tissues in SL, SL-HF and NL-HF rats compared to NL rats in adulthood. The opposite trends were observed in SL-FO rats. Moreover, in vitro, recombinant NRG4 protein reduced lipid accumulation by inhibiting DNL gene expression in fatty HepG2 cells stimulated with sodium oleate. In HPAs, eicosapentaenoic acid (EPA) treatment elevated NRG4 production and caused adipocyte browning, and these effects were abrogated by PPARG antagonism. In conclusion, a postweaning n-3 PUFA diet enhanced Nrg4 expression in adipose tissues, associated with attenuation of NAFLD induced by SL rearing. Additionally, external NRG4 reduced lipogenesis in steatotic hepatocytes. Thus, white adipose tissue browning induced by n-3 PUFAs may promote NRG4 production through the PPARG pathway.

Fish Oil Enriched in EPA, but Not in DHA, Reverses the Metabolic Syndrome and Adipocyte Dysfunction Induced by a High-Fat Diet

This study aimed to investigate the effects of two commercially available fish oils (FOs) containing different proportions of two omega-3 fatty acids (FA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on the metabolic and endocrine dysfunctions of white adipose tissue resulting from obesity. Male C57BL/6J mice, 8 weeks old, received a control or high-fat diet (CO and HF groups, with 9% and 59% energy from fat, respectively) for 8 weeks. The next 8 weeks, the HF group was subdivided into HF, HF+FO/E (HF+5:1 EPA:DHA), and HF+FO/D (HF+5:1 DHA:EPA). Supplementation was performed by gavage, three times a week. All groups that received the HF diet had lower food and caloric intake, but a higher fat intake, body weight (BW) gain, glucose intolerance, and a significant increase in inguinal (ING), retroperitoneal (RP), and epididymal (EPI) adipose tissues when compared to the CO group. Additionally, HF and HF+FO/D groups showed insulin resistance, adipocyte hypertrophy, increased lipolysis and secretion of TNF-α, resistin and IL-10 adipokines by ING and RP adipocytes, and adiponectin only by the HF+FO/D group in ING adipocytes. All of these effects were completely reversed in the HF+FO/E group, which also showed partial reversion in BW gain and glucose intolerance. Both the HF+FO/E and HF+FO/D groups showed a reduction in ING and RP adipose depots when compared to the HF group, but only HF+FO/E in the EPI depot. HF+FO/E, but not HF+FO/D, was able to prevent the changes triggered by obesity in TNF-α, Il-10, and resistin secretion in ING and RP depots. These results strongly suggest that different EPA:DHA ratios have different impacts on the adipose tissue metabolism, FO being rich in EPA, but not in DHA, and effective in reversing the changes induced by obesity.

Omega-3 Polyunsaturated Fatty Acids Prevent Nonalcoholic Steatohepatitis (NASH) and Stimulate Adipogenesis

The increasing impact of obesity on global human health intensifies the importance of studies focusing on agents interfering with the metabolism and remodeling not only of the white adipose tissue (WAT) but also of the liver. In the present study, we have addressed the impact of n-3 PUFA in adipose cells' proliferation and adipogenesis, as well as in the hepatic lipid profile and morphology. Mice were induced to obesity by the consumption of a high-fat diet (HFD) for 16 weeks. At the 9th week, the treatment with fish oil (FO) was initiated and maintained until the end of the period. The FO treatment reduced the animals' body mass, plasma lipids, glucose, plasma transaminases, liver mass, triacylglycerol, and cholesterol liver content when compared to animals consuming only HFD. FO also decreased the inguinal (ing) WAT mass, reduced adipocyte volume, increased adipose cellularity (hyperplasia), and increased the proliferation of adipose-derived stromal cells (AdSCs) which corroborates the increment in the proliferation of 3T3-L1 pre-adipocytes or AdSCs treated in vitro with n-3 PUFA. After submitting the in vitro treated (n-3 PUFA) cells, 3T3-L1 and AdSCs, to an adipogenic cocktail, there was an increase in the mRNA expression of adipogenic transcriptional factors and other late adipocyte markers, as well as an increase in lipid accumulation when compared to not treated cells. Finally, the expression of browning-related genes was also higher in the n-3 PUFA treated group. We conclude that n-3 PUFA exerts an attenuating effect on body mass, dyslipidemia, and hepatic steatosis induced by HFD. FO treatment led to decreasing adiposity and adipocyte hypertrophy in ingWAT while increasing hyperplasia. Data suggest that FO treatment might induce recruitment (by increased proliferation and differentiation) of new adipocytes (white and/or beige) to the ingWAT, which is fundamental for the healthy expansion of WAT.

Novel high-docosahexaenoic-acid tuna oil supplementation modulates gut microbiota and alleviates obesity in high-fat diet mice

Studies have documented the benefits of fish oil in different diseases because of its high n-3 polyunsaturated fatty acid content. However, these studies mostly used commercially available fish oil supplements with a ratio of 18/12 for eicosapentaenoic acid and docosahexaenoic acid (DHA). However, increasing DHA content for this commonly used ratio might bring out a varied metabolic effect, which have remained unclear. Thus, in this study, a novel tuna oil (TO) was applied to investigate the effect of high-DHA content on the alteration of the gut microbiota and obesity in high-fat diet mice. The results suggest that high-DHA TO (HDTO) supplementation notably ameliorates obesity and related lipid parameters and restores the expression of lipid metabolism-related genes. The benefits of TOs were derived from their modification of the gut microbiota composition and structure in mice. A high-fat diet triggered an increased Firmicutes/Bacteroidetes ratio that was remarkably restored by TOs. The number of obesity-promoting bacteria-Desulfovibrio, Paraeggerthella, Terrisporobacter, Millionella, Lachnoclostridium, Anaerobacterium, and Ruminiclostridium-was dramatically reduced. Desulfovibrio desulfuricans, Alistipes putredinis, and Millionella massiliensis, three dysbiosis-related species, were especially regulated by HDTO. Regarding the prevention of obesity, HDTO outperforms the normal TO. Intriguingly, HDTO feeding to HFD-fed mice might alter the arginine and proline metabolism of intestinal microbiota.

Anti-obesity potentiality of Tapra fish (Opisthopterus tardoore) oil

In this present investigation, we have extracted and characterized the Tapra fish oil as well as applied it to evaluate anti-obesity potentiality. The Tapra fish oil had 1.14 ± 0.10 mg KOH/g of acid value, 129.8 ± 5.09 mg KOH/g of saponification number, 2.67 ± 0.67 mEq/kg of peroxide value, 121.9 ± 2.14 mg of iodine value, and 17.67 ± 1.45 totox value. Gas Chromatography-Mass Spectrometric analysis clearly revealed the presence of nine different fatty acids. When the fish oil was applied to high-fat diet-induced obese mice, it showed significant reduction of body weight, Body Mass Index, and serum lipid profiles compared to the high-fat diet-induced obese mice. The levels of leptin and TNF-α were moderately reduced in fish oil treated high-fat diet-induced obese mice than control obese mice. In conclusion, the Tapra fish oil was enriched with essential fatty acids and it could be used as an antiobese food supplement. PRACTICAL APPLICATIONS: Considering the adverse effects of drugs used for the treatment of obesity, there is always a need to find out the alternatives. While the anti-obesity potentialities of different sea fish oil have been documented, the same for the Tapra fish (Opisthopterus tardoore) oil has not been studied at all. The extracted Tapra fish oil was found good in quality. Administration of fish oil in the mice exhibited anti-obesity effect in terms of lowering body weight, Body Mass Index, and serum lipid profiles, leptin, and TNF-α in mice model. These findings are fostering new therapeutic approaches to obesity treatment.

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.

Fish oil reverses metabolic syndrome, adipocyte dysfunction, and altered adipokines secretion triggered by high-fat diet-induced obesity

The effect of fish oil (FO) treatment on high-fat (HF) diet-induced obesity and metabolic syndrome was addressed by analyzing dysfunctions in cells of different adipose depots. For this purpose, mice were initially induced to obesity for 8 weeks following a treatment with FO containing high concentration of EPA compared to DHA (5:1), for additional 8 weeks (by gavage, 3 times per week). Despite the higher fat intake, the HF group showed lower food intake but higher body weight, glucose intolerance and insulin resistance, significant dyslipidemia and increased liver, subcutaneous (inguinal-ING) and visceral (retroperitoneal-RP) adipose depots mass, accompanied by adipocyte hypertrophy and decreased cellularity in both adipose tissue depots. FO treatment reversed all these effects, as well as it improved the metabolic activities of isolated adipocytes, such as glucose uptake and lipolysis in both depots, and de novo synthesis of fatty acids in ING adipocytes. HF diet also significantly increased both the pro and anti-inflammatory cytokines expression by adipocytes, while HF + FO did not differ from control group. Collectively, these data show that the concomitant administration of FO with the HF diet is able to revert metabolic changes triggered by the diet-induced obesity, as well as to promote beneficial alterations in adipose cell activities. The main mechanism underlying all systemic effects involves direct and differential effects on ING and RP adipocytes.

Palmitoleic Acid Decreases Non-alcoholic Hepatic Steatosis and Increases Lipogenesis and Fatty Acid Oxidation in Adipose Tissue From Obese Mice

We recently demonstrated that palmitoleic acid (C16:1n7), a monounsaturated fatty acid, increases the metabolic and oxidative capacity of 3T3-L1 adipocytes. Herein, the effect of 16:1n7 supplementation on metabolic parameters on white adipose tissue (WAT) and liver of obese mice induced by a high-fat diet (HFD) was addressed by analyzing metabolic (dys)function and altered genes expression in adipose tissue, as well as liver and serum biochemistry analysis. For this purpose, mice were induced to obesity for 8 weeks, and from the 5th week, they received 16:1n7 (300 mg/kg per day) or water for 30 days, by gavage. Subcutaneous inguinal (ING) and epididymal (EPI) WAT were removed for analysis of metabolic, (anti)inflammatory, adipogenic, and thermogenic genes expression by real-time reverse transcriptase-polymerase chain reaction. Additionally, metabolic activities of isolated adipocytes, such as glucose uptake, lipogenesis (triacylglycerol esterification), β-oxidation, and lipolysis in ING adipocytes, were also assessed. Despite the higher fat intake, the HFD group showed lower food intake but higher body weight, increased glucose, significant dyslipidemia, and increased liver and adipose depot mass, accompanied by liver steatosis. The 16:1n7 supplementation slowed down the body mass gain and prevented the increase of lipids in the liver. HFD+n7 animals presented increased fatty acid oxidation and lipogenesis compared to control, but no effect was observed on lipolysis and glucose uptake in ING isolated adipocytes. Besides, 16:1n7 increased the content of the mRNA encoding FABP4, but partially prevented the expression of genes encoding ATGL, HSL, perilipin, lipin, C/EBP-α, PPAR-γ, C/EBP-β, CPT1, NRF1, TFAM, PRDM16, and nitric oxide synthase 2 in ING depot from HFD group of animals. Finally, HFD increased Mcp1 and Tnfα expression, and 16:1n7 promoted a more marked increase in it. In summary, the data show that palmitoleic acid promotes metabolic changes and partially prevents the increase in gene expression on adipocytes triggered by obesity, suggesting that HFD+n7 animals do not require the same magnitude of metabolic adaptation to cope with energy demand from the HFD. In the long term, the effects of 16:1n7 may be more evident and beneficial for the function/dysfunction of WAT from an obese organism, with relevant repercussions in the systemic metabolic homeostasis.

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.

Melatonin Supplementation Attenuates the Pro-Inflammatory Adipokines Expression in Visceral Fat from Obese Mice Induced by A High-Fat Diet

Obesity is defined as a condition of abnormal or excessive fat accumulation in white adipose tissue that results from the exacerbated consumption of calories associated with low energy expenditure. Fat accumulation in both adipose tissue and other organs contributes to a systemic inflammation leading to the development of metabolic disorders such as type 2 diabetes, hypertension, and dyslipidemia. Melatonin is a potent antioxidant and improves inflammatory processes and energy metabolism. Using male mice fed a high-fat diet (HFD—59% fat from lard and soybean oil; 9:1) as an obesity model, we investigated the effects of melatonin supplementation on the prevention of obesity-associated complications through an analysis of plasma biochemical profile, body and fat depots mass, adipocytes size and inflammatory cytokines expression in epididymal (EPI) adipose depot. Melatonin prevented a gain of body weight and fat depot mass as well as adipocyte hypertrophy. Melatonin also reversed the increase of total cholesterol, triglycerides and LDL-cholesterol. In addition, this neurohormone was effective in completely decreasing the inflammatory cytokines leptin and resistin in plasma. In the EPI depot, melatonin reversed the increase of leptin, Il-6, Mcp-1 and Tnf-α triggered by obesity. These data allow us to infer that melatonin presents an anti-obesity effect since it acts to prevent the progression of pro-inflammatory markers in the epididymal adipose tissue together with a reduction in adiposity.

A Mixture of Polyunsaturated Fatty Acids ω-3 and ω-6 Reduces Melanoma Growth by Inhibiting Inflammatory Mediators in the Murine Tumor Microenvironment

Background: Although it has been previously demonstrated that acute inflammation can promote the tumor growth of a sub-tumorigenic dose of melanoma cells through of 5-lipoxygenase inflammatory pathway and its product leukotriene B_4, and also that the peritumoral treatment with eicosapentaenoic acid and its product, leukotriene B₅, reduces the tumor development, the effect of the treatment by gavage with omega-3 and omega-6 in the tumor microenvironment favorable to melanoma growth associated with acute inflammation has never been studied. Methods: C57BL/6 mice were coinjected with 1 × 10⁶ apoptotic cells plus 1 × 10³ viable melanoma cells into the subcutaneous tissue and treated by gavage with omega-3-rich fish oil or omega-6-rich soybean oil or a mixture of these oils (1:1 ratio) during five consecutive days. Results: The treatment by gavage with a mixture of fish and soybean oils (1:1 ratio) both reduced the melanoma growth and the levels of leukotriene B₄ (LTB₄), prostaglandin E₂ (PGE₂), PGE₂/prostaglandin E₃ (PGE₃) ratio, and CXC ligand 1 (CXCL1) and increased the levels of interleukin 10 (IL-10) to IL-10/CXCL1 ratio in the melanoma microenvironment. Conclusion: The oral administration of a 1:1 mixture of fish oil and soybean oil was able to alter the release of inflammatory mediators that are essential for a microenvironment favorable to the melanoma growth in mice, whereas fish oil or soybean oil alone was ineffective.

Ginkgo biloba Extract Modulates the Retroperitoneal Fat Depot Proteome and Reduces Oxidative Stress in Diet-Induced Obese Rats

The rapid increase in the number of individuals with obesity, over the past four decades, is triggered by a number of complex interactions among factors. Despite the plethora of treatments available, side effects are commonly observed and, in this context, herbal medicines have been employed as an alternative form of therapy. Ginkgo biloba extract (GbE) has been described as a promising new pharmacological approach to treat obesity. In order to better comprehend the mechanisms involved with this potential effect, the present study evaluated the effects of GbE treatment on diet-induced obese rats, focusing on the proteome and the oxidative stress defense system of visceral adipose tissue. After 14 days treatment, GbE significantly modulated 25 proteins. Retroperitoneal adipose tissue of treated animals exhibited higher amounts of proteins associated with adipogenesis (decorin), carbon metabolism and mitochondrial function (citrate synthase), and a concomitant reduction in adipocyte hypertrophy. In parallel, GbE down-regulated proteins involved in oxidative stress (peroxiredoxin) and the inflammatory response (complement C3, mast cell protease 1, and Ig gamma-2B chain C region). Moreover, also related to oxidative stress defense, GbE stimulated catalase activity, reduced malondialdehyde levels (lipid peroxidation indicator), and increased lactoylglutathione lyase levels. It was concluded that GbE acts as an antioxidant agent, and improved the proteome profile and oxidative stress response in the adipose tissue of diet-induced obese rats.

Potential Anti-obesogenic Effects of Ginkgo biloba Observed in Epididymal White Adipose Tissue of Obese Rats

Exacerbated expansion of adipose tissue seen in diet-induced obesity leads to endocrine dysfunction and disturbance in adipokine secretion, with such abnormal profile positively associated with type 2 diabetes and other mild chronic inflammatory conditions. Ginkgo biloba extract (GbE), a mixture of polyphenols with antioxidant properties, has been recently investigated in a variety of experimental models of endocrine dysfunction, with several potentially beneficial effects identified, including improvement in insulin sensitivity in obese rats, and reduction of weight gain in ovariectomy-induced obesity and diet-induced obesity. The aim of this study was to investigate in high fat diet-induced obese male rats the effects of GbE supplementation for 2 weeks on adipocyte volume and adipose tissue lipid accumulation. GbE supplementation was effective in reducing energy intake in obese rats compared to the saline-treated placebo group. Epididymal adipocyte volume was reduced in GbE-supplemented rats, as were epididymal [1-¹⁴C]-acetate incorporation into fatty acids, perilipin (Plin 1) and fatty acid synthase (Fasn) mRNA, and FAS protein levels. Adipocyte hypertrophy in obesity is associated with insulin resistance, and in the present study we observed a reduction in the adipocyte volume of GbE-supplemented obese rats to dimensions equivalent to adipocytes from non-obese rats. GbE supplementation significantly reduced acetate accumulation and tended to reduce [³H]-oleate incorporation, into epididymal adipose tissue, suggesting a potentially anti-obesogenic effect in longer term therapies. Further studies that investigate the effects of GbE supplementation in other experimental models are required to fully elucidate its suggested beneficial effects on mild chronic inflammatory conditions.

Melatonin Supplementation Decreases Hypertrophic Obesity and Inflammation Induced by High-Fat Diet in Mice

Obesity results from critical periods of positive energy balance characterized by caloric intake greater than energy expenditure. This disbalance promotes adipose tissue dysfunction which is related to other comorbidities. Melatonin is a low-cost therapeutic agent and studies indicate that its use may improve obesity-related disorders. To evaluate if the melatonin is efficient in delaying or even blocking the damages caused by excessive ingestion of a high-fat diet (HFD) in mice, as well as improving the inflammatory profile triggered by obesity herein, male C57BL/6 mice of 8 weeks were induced to obesity by a HFD and treated for 10 weeks with melatonin. The results demonstrate that melatonin supplementation attenuated serum triglyceride levels and total and LDL cholesterol and prevented body mass gain through a decreased lipogenesis rate and increased lipolytic capacity in white adipocytes, with a concomitant increment in oxygen consumption and Pgc1a and Prdm16 expression. Altogether, these effects prevented adipocyte hypertrophy caused by HFD and reflected in decreased adiposity. Finally, melatonin supplementation reduced the crown-like-structure (CLS) formation, characteristic of the inflammatory process by macrophage infiltration into white adipose tissue of obese subjects, as well as decreased the gene expression of inflammation-related factors, such as leptin and MCP1. Thus, the melatonin can be considered a potential therapeutic agent to attenuate the metabolic and inflammatory disorders triggered by obesity.

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).

Palmitoleic acid (16:1n7) increases oxygen consumption, fatty acid oxidation and ATP content in white adipocytes

Background

We have recently demonstrated that palmitoleic acid (16:1n7) increases lipolysis, glucose uptake and glucose utilization for energy production in white adipose cells. In the present study, we tested the hypothesis that palmitoleic acid modulates bioenergetic activity in white adipocytes.

Methods

For this, 3 T3-L1 pre-adipocytes were differentiated into mature adipocytes in the presence (or absence) of palmitic (16:0) or palmitoleic (16:1n7) acid at 100 or 200 μM. The following parameters were evaluated: lipolysis, lipogenesis, fatty acid (FA) oxidation, ATP content, oxygen consumption, mitochondrial mass, citrate synthase activity and protein content of mitochondrial oxidative phosphorylation (OXPHOS) complexes.

Results

Treatment with 16:1n7 during 9 days raised basal and isoproterenol-stimulated lipolysis, FA incorporation into triacylglycerol (TAG), FA oxidation, oxygen consumption, protein expression of subunits representing OXPHOS complex II, III, and V and intracellular ATP content. These effects were not observed in adipocytes treated with 16:0.

Conclusions

Palmitoleic acid, by concerted action on lipolysis, FA esterification, mitochondrial FA oxidation, oxygen consumption and ATP content, does enhance white adipocyte energy expenditure and may act as local hormone.

Omega-3 fatty acids revert high-fat diet-induced neuroinflammation but not recognition memory impairment in rats

Neuroinflammation is a consequence of overeating and may predispose to the development of cognitive decline and neurological disorders. This study aimed to evaluate the impact of omega-3 supplementation on memory and neuroinflammatory markers in rats fed a high-fat diet. Male Wistar rats were divided into four groups: standard diet (SD); standard diet + omega-3 (SD + O); high fat diet (HFD); and high fat diet + omega-3 (HFD + O). Diet administration was performed for 20 weeks and omega-3 supplementation started at the 16th week. HFD significantly increased body weight, while omega-3 supplementation did not modify the total weight gain. However, animals from the HFD + O group showed a lower level of visceral fat along with an improvement in insulin sensitivity following HFD. Thus, our results demonstrate a beneficial metabolic role of omega-3 following HFD. On the other hand, HFD animals presented an impairment in object recognition memory, which was not recovered by omega-3. In addition, there was an increase in GFAP-positive cells in the cerebral cortex of the HFD group, showing that omega-3 supplementation can be effective to decrease astrogliosis. However, no differences in GFAP number of cells were found in the hippocampus. We also demonstrated a significant increase in gene expression of pro-inflammatory cytokines IL-6 and TNF-α in cerebral cortex of the HFD group, reinforcing the anti-inflammatory role of this family of fatty acids. In summary, omega-3 supplementation was not sufficient to reverse the memory deficit caused by HFD, although it played an important role in reducing the neuroinflammatory profile. Therefore, omega-3 fatty acids may play an important role in the central nervous system, preventing the progression of neuroinflammation in obesity.

Fenofibrate reverses changes induced by high-fat diet on metabolism in mice muscle and visceral adipocytes

The effect of fenofibrate on the metabolism of skeletal muscle and visceral white adipose tissue of diet-induced obese (DIO) mice was investigated. C57BL/6J male mice were fed either a control or high-fat diet for 8 weeks. Fenofibrate (50 mg/Kg BW, daily) was administered by oral gavage during the last two weeks of the experimental period. Insulin-stimulated glucose metabolism in soleus muscles, glucose tolerance test, insulin tolerance test, indirect calorimetry, lipolysis of visceral white adipose tissue, expression of miR-103-3p in adipose tissue, and miR-1a, miR-133a/b, miR-206, let7b-5p, miR-23b-3p, miR-29-3p, miR-143-3p in soleus muscle, genes related to glucose and fatty acid metabolism in adipose tissue and soleus muscle, and proteins (phospho-AMPKα2, Pgc1α, Cpt1b), intramuscular lipid staining, and activities of fatty acid oxidation enzymes in skeletal muscle were investigated. In DIO mice, fenofibrate prevented weight gain induced by HFD feeding by increasing energy expenditure; improved whole body glucose homeostasis, and in skeletal muscle, increased insulin dependent glucose uptake, miR-1a levels, reduced intramuscular lipid accumulation, and phospho-AMPKα2 levels. In visceral adipose tissue of obese mice, fenofibrate decreased basal lipolysis rate and visceral adipocytes hypertrophy, and induced the expression of Glut-4, Irs1, and Cav-1 mRNA and miR-103-3p suggesting a higher insulin sensitivity of the adipocytes. The evidence is presented herein that beneficial effects of fenofibrate on body weight, glucose homeostasis, and muscle metabolism might be related to its action in adipose tissue. Moreover, fenofibrate regulates miR-1a-3p in soleus and miR-103-3p in adipose tissue, suggesting these microRNAs might contribute to fenofibrate beneficial effects on metabolism.

The ineluctable constraints of thermodynamics in the aetiology of obesity

We exploit the detail-independence feature of thermodynamics to examine issues related to the development of obesity. We adopt a 'global' approach consistent with focus on the first law of thermodynamics - namely that the metabolic energy provided by dietary foodstuffs has only three possible fates: the performance of work (be it microscopic or macroscopic), the generation of heat, or storage - primarily in the form of adipose tissue. Quantification of the energy expended, in the form of fat metabolised, during selected endurance events, reveals the inherent limitation of over-reliance on exercise as a primary agent of weight loss. This result prompts examination of various (non-exercise based) possibilities of increasing the rate of heat loss. Since these, too, give little cause for optimism, we are obliged to conclude that obesity can be prevented, or weight loss achieved, only if exercise is supplemented by reduction of food intake.

Effects of plant- and animal-based high-fat diets on lipid storage and distribution in environmental bacteria-colonized gnotobiotic mice

Different edible oils such as lard and soybean oil have been reported to interact with the gut microbiota, affecting host lipid metabolism. However, whether bacteria derived from the environment influence host lipid metabolism remains unclear. This study aimed to clarify the roles of environmental bacteria in host lipid storage and distribution with various edible oils. Gnotobiotic C57BL/6JNarl mice were inoculated with Lysinibacillus xylanilyticus and Paenibacillus azoreducens and then fed either a normal diet (LabDiet 5010, control group) or a diet containing 60% lard (L-group) or soybean oil (S-group) for 18 months. Interestingly, the S-group accumulated massive amounts of white adipose tissue compared to the L- and control groups, while the L-group displayed more hepatic steatosis and fatty droplets than the other groups. The expression of fatty acid synthase (FAS), hydroxymethylglutaryl-coenzyme A reductase (HMGCR), sterol regulatory element-binding protein 2 (SREBP2), and peroxisome proliferator-activated receptor gamma (PPARγ) in the livers of the L-group were markedly elevated compared to the S-group. FAS and PPARγ protein levels were also markedly elevated. However, there were no differences in the expression of the pro-inflammatory cytokines interleukin-6 and tumor necrosis factor-α between the groups. Our results suggest that environmental bacteria may affect host hepatic inflammation and lipid distribution in the presence of high-fat diets, with different effects depending on the fat type consumed.

Ginkgo biloba Extract (GbE) Stimulates the Hypothalamic Serotonergic System and Attenuates Obesity in Ovariectomized Rats

Menopause is associated with increased risk to develop obesity but the mechanisms involved are not fully understood. We have shown that Ginkgo biloba extract (GbE) improved diet-induced obesity. Since GbE might be effective in the treatment of obesity related to menopause, avoiding the side effects of hormone replacement therapy, we investigated the effect of GbE on hypothalamic systems controlling energy homeostasis. Wistar rats were either ovariectomized (OVX) or Sham-operated. After 2 months, either 500 mg.kg^-1 of GbE or vehicle were administered daily by gavage for 14 days. A subset of animals received an intracerebroventricular (i.c.v.) injection of serotonin (300 μg) or vehicle and food intake was measured after 12 and 24 h. Another subset was submitted to in vivo microdialysis and 5-HT levels of the medial hypothalamus were measured by high performance liquid chromatography, before and up to 2 h after the administration of 500 mg.kg^-1 of GbE. Additional animals were used for quantification of 5-HT_1A, 5-HT_1B, 5-HT_2C, 5-HTT, and pro-opiomelanocortin hypothalamic protein levels by Western blotting. OVX increased food intake and body weight and adiposity while GbE attenuated these alterations. i.c.v. serotonin significantly reduced food intake in Sham, Sham + GbE, and OVX + GbE groups while it failed to do so in the OVX group. In the OVX rats, GbE stimulated 5-HT microdialysate levels while it reduced hypothalamic 5-HTT protein levels. The results indicate that GbE improved the ovariectomy-induced resistance to serotonin hypophagia, at least in part through stimulation of the hypothalamic serotonergic activity. Since body weight gain is one of the most important consequences of menopause, the stimulation of the serotonergic transmission by GbE may represent a potential alternative therapy for menopause-related obesity.

Combination of a high-fat diet with sweetened condensed milk exacerbates inflammation and insulin resistance induced by each separately in mice

Obesogenic diets increase body weight and cause insulin resistance (IR), however, the association of these changes with the main macronutrient in the diet remains to be elucidated. Male C57BL/6 mice were fed with: control (CD), CD and sweetened condensed milk (HS), high-fat (HF), and HF and condensed milk (HSHF). After 2 months, increased body weight, glucose intolerance, adipocyte size and cholesterol levels were observed. As compared with CD, HS ingested the same amount of calories whereas HF and HSHF ingested less. HS had increased plasma AST activity and liver type I collagen. HF caused mild liver steatosis and hepatocellular damage. HF and HSHF increased LDL-cholesterol, hepatocyte and adipocyte hypertrophy, TNF-α by macrophages and decreased lipogenesis and adiponectin in adipose tissue (AT). HSHF exacerbated these effects, increasing IR, lipolysis, mRNA expression of F4/80 and leptin in AT, Tlr-4 in soleus muscle and IL-6, IL-1β, VCAM-1, and ICAM-1 protein in AT. The three obesogenic diets induced obesity and metabolic dysfunction. HS was more proinflammatory than the HF and induced hepatic fibrosis. The HF was more detrimental in terms of insulin sensitivity, and it caused liver steatosis. The combination HSHF exacerbated the effects of each separately on insulin resistance and AT inflammatory state.

Obesity is a concern for bone health with aging

Accumulating evidence supports a complex relationship between adiposity and osteoporosis in overweight/obese individuals, with local interactions and endocrine regulation by adipose tissue on bone metabolism and fracture risk in elderly populations. This review was conducted to summarize existing evidence to test the hypothesis that obesity is a risk factor for bone health in aging individuals. Mechanisms by which obesity adversely affects bone health are believed to be multiple, such as an alteration of bone-regulating hormones, inflammation, oxidative stress, the endocannabinoid system, that affect bone cell metabolism are discussed. In addition, evidence on the effect of fat mass and distribution on bone mass and quality is reviewed together with findings relating energy and fat intake with bone health. In summary, studies indicate that the positive effects of body weight on bone mineral density cannot counteract the detrimental effects of obesity on bone quality. However, the exact mechanism underlying bone deterioration in the obese is not clear yet and further research is required to elucidate the effect of adipose depots on bone and fracture risk in the obese population.