Chronic administration of palmitoleic acid reduces insulin resistance and hepatic lipid accumulation in KK-Ay Mice with genetic type 2 diabetes

Pelleting in Associated with Sodium Monensin Increases the Conjugated Linoleic Acids Concentration in the Milk of Dairy Cows Fed Canola Seeds

To evaluate the effects of the pelleting and the addition of sodium monensin on production, the chemical and lipid composition of milk and butter physical characteristics, 4 Holstein dairy cows (135 days of lactation) with an average milk production of 14.7 kg/d, were supplemented with a concentrate containing ground canola seeds. The cows were assigned to a 4×4 Latin square design with a 2×2 factorial arrangement of treatments: i) ground maize, soybean meal, mineral and vitamin supplements, and ground canola seeds (CG); ii) CG concentrate with 31.5 mg of monensin added per kg of dry matter (DM); iii) CG pelleted concentrate; iv) CG concentrate with monensin addition pelleted. There was no difference in milk production and composition. The addition of monensin increased milk concentration of polyunsaturated fatty acids (PUFA), the PUFA/saturated fatty acids (SFA) ratio, and omega 6. The pelleting increased the concentration of monounsaturated fatty acids, the PUFA/SFA ratio, and the omega 6/omega 3 ratio, but decreased the concentration of SFA. The association between pelleting and the addition of monensin increased the concentration of conjugated linoleic acids by 46.9%. The physical characteristics of butter were not affected by the evaluated diets. We concluded that the concentrate with 31.5 mg of monensin added per kg DM basis combined with the pelleting improves the lipid composition of milk from Holstein cows that are on pasture and supplemented with ground canola seeds, without changing the production, milk composition, and spreadability of butter.

Palmitoleate Reverses High Fat-induced Proinflammatory Macrophage Polarization via AMP-activated Protein Kinase (AMPK)

A rise in tissue-embedded macrophages displaying "M1-like" proinflammatory polarization is a hallmark of metabolic inflammation during a high fat diet or obesity. Here we show that bone marrow-derived macrophages (BMDM) from high fat-fed mice retain a memory of their dietary environment in vivo (displaying the elevated proinflammatory genes Cxcl1, Il6, Tnf, Nos2) despite 7-day differentiation and proliferation ex vivo. Notably, 6-h incubation with palmitoleate (PO) reversed the proinflammatory gene expression and cytokine secretion seen in BMDM from high fat-fed mice. BMDM from low fat-fed mice exposed to palmitate (PA) for 18 h ex vivo also showed elevated expression of proinflammatory genes (Cxcl1, Il6, Tnf, Nos2, and Il12b) associated with M1 polarization. Conversely, PO treatment increased anti-inflammatory genes (Mrc1, Tgfb1, Il10, Mgl2) and oxidative metabolism, characteristic of M2 macrophages. Therefore, saturated and unsaturated fatty acids bring about opposite macrophage polarization states. Coincubation of BMDM with both fatty acids counteracted the PA-induced Nos2 expression in a PO dose-dependent fashion. PO also prevented PA-induced IκBα degradation, RelA nuclear translocation, NO production, and cytokine secretion. Mechanistically, PO exerted its anti-inflammatory function through AMP-activated protein kinase as AMP kinase knockout or inhibition by Compound C offset the PO-dependent prevention of PA-induced inflammation. These results demonstrate a nutritional memory of BMDM ex vivo, highlight the plasticity of BMDM polarization in response to saturated and unsaturated fatty acids, and identify the potential to reverse diet- and saturated fat-induced M1-like polarization by administering palmitoleate. These findings could have applicability to reverse obesity-linked inflammation in metabolically relevant tissues.

Hepatic oleate regulates adipose tissue lipogenesis and fatty acid oxidation

Hepatic steatosis is associated with detrimental metabolic phenotypes including enhanced risk for diabetes. Stearoyl-CoA desaturases (SCDs) catalyze the synthesis of MUFAs. In mice, genetic ablation of SCDs reduces hepatic de novo lipogenesis (DNL) and protects against diet-induced hepatic steatosis and adiposity. To understand the mechanism by which hepatic MUFA production influences adipose tissue stores, we created two liver-specific transgenic mouse models in the SCD1 knockout that express either human SCD5 or mouse SCD3, that synthesize oleate and palmitoleate, respectively. We demonstrate that hepatic de novo synthesized oleate, but not palmitoleate, stimulate hepatic lipid accumulation and adiposity, reversing the protective effect of the global SCD1 knockout under lipogenic conditions. Unexpectedly, the accumulation of hepatic lipid occurred without induction of the hepatic DNL program. Changes in hepatic lipid composition were reflected in plasma and in adipose tissue. Importantly, endogenously synthesized hepatic oleate was associated with suppressed DNL and fatty acid oxidation in white adipose tissue. Regression analysis revealed a strong correlation between adipose tissue lipid fuel utilization and hepatic and adipose tissue lipid storage. These data suggest an extrahepatic mechanism where endogenous hepatic oleate regulates lipid homeostasis in adipose tissues.

Redirection of metabolic flux for high levels of omega-7 monounsaturated fatty acid accumulation in camelina seeds

Seed oils enriched in omega-7 monounsaturated fatty acids, including palmitoleic acid (16:1∆9) and cis-vaccenic acid (18:1∆11), have nutraceutical and industrial value for polyethylene production and biofuels. Existing oilseed crops accumulate only small amounts (<2%) of these novel fatty acids in their seed oils. We demonstrate a strategy for enhanced production of omega-7 monounsaturated fatty acids in camelina (Camelina sativa) and soybean (Glycine max) that is dependent on redirection of metabolic flux from the typical ∆9 desaturation of stearoyl (18:0)-acyl carrier protein (ACP) to ∆9 desaturation of palmitoyl (16:0)-acyl carrier protein (ACP) and coenzyme A (CoA). This was achieved by seed-specific co-expression of a mutant ∆9-acyl-ACP and an acyl-CoA desaturase with high specificity for 16:0-ACP and CoA substrates, respectively. This strategy was most effective in camelina where seed oils with ~17% omega-7 monounsaturated fatty acids were obtained. Further increases in omega-7 fatty acid accumulation to 60-65% of the total fatty acids in camelina seeds were achieved by inclusion of seed-specific suppression of 3-keto-acyl-ACP synthase II and the FatB 16:0-ACP thioesterase genes to increase substrate pool sizes of 16:0-ACP for the ∆9-acyl-ACP desaturase and by blocking C18 fatty acid elongation. Seeds from these lines also had total saturated fatty acids reduced to ~5% of the seed oil versus ~12% in seeds of nontransformed plants. Consistent with accumulation of triacylglycerol species with shorter fatty acid chain lengths and increased monounsaturation, seed oils from engineered lines had marked shifts in thermotropic properties that may be of value for biofuel applications.

Palmitoleic acid (n-7) increases white adipocytes GLUT4 content and glucose uptake in association with AMPK activation

Background

Palmitoleic acid was previously shown to improve glucose homeostasis by reducing hepatic glucose production and by enhancing insulin-stimulated glucose uptake in skeletal muscle. Herein we tested the hypothesis that palmitoleic acid positively modulates glucose uptake and metabolism in adipocytes.

Methods

For this, both differentiated 3 T3-L1 cells treated with either palmitoleic acid (16:1n7, 200 μM) or palmitic acid (16:0, 200 μM) for 24 h and primary adipocytes from mice treated with 16:1n7 (300 mg/kg/day) or oleic acid (18:1n9, 300 mg/kg/day) by gavage for 10 days were evaluated for glucose uptake, oxidation, conversion to lactate and incorporation into fatty acids and glycerol components of TAG along with the activity and expression of lipogenic enzymes.

Results

Treatment of adipocytes with palmitoleic, but not oleic (in vivo) or palmitic (in vitro) acids, increased basal and insulin-stimulated glucose uptake and GLUT4 mRNA levels and protein content. Along with uptake, palmitoleic acid enhanced glucose oxidation (aerobic glycolysis), conversion to lactate (anaerobic glycolysis) and incorporation into glycerol-TAG, but reduced de novo fatty acid synthesis from glucose and acetate and the activity of lipogenic enzymes glucose 6-phosphate dehydrogenase and ATP-citrate lyase. Importantly, palmitoleic acid induction of adipocyte glucose uptake and metabolism were associated with AMPK activation as evidenced by the increased protein content of phospho(p)Thr172AMPKα, but no changes in pSer473Akt and pThr308Akt. Importantly, such increase in GLUT4 content induced by 16:1n7, was prevented by pharmacological inhibition of AMPK with compound C.

Conclusions

In conclusion, palmitoleic acid increases glucose uptake and the GLUT4 content in association with AMPK activation.

Fat sensing and metabolic syndrome

Overconsumption of dietary fat contributes to the development of obesity and metabolic syndrome. Recent evidence suggests that high dietary fat may promote these metabolic states not only by providing calories but also by inducing impaired control of energy balance. In normal metabolic states, fat interacts with various organs or receptors to generate signals for the regulation of energy balance. Many of these interactions are impaired by high-fat diets or in obesity, contributing to the development or maintenance of obesity. These impairments may arise largely from fundamental alterations in the hypothalamus where all peripheral signals are integrated to regulate energy balance. This review focuses on various mechanisms by which fat is sensed at different stages of ingestion, circulation, storage, and utilization to regulate food intake, and how these individual mechanisms are altered by high-fat diets or in obesity.

WITHDRWAN: Purified palmitoleic acid for the reduction of high-sensitivity C-reactive protein and serum lipids: a double-blinded, randomized, placebo controlled study

BACKGROUND

Purified palmitoleic acid (16-1; omega-7) has shown lipid-lowering and anti-inflammatory benefits in open label, epidemiologic, and animal studies.

OBJECTIVE

Our objective was to perform the first randomized controlled trial of purified palmitoleic acid supplementation in humans.

METHODS

Adults with dyslipidemia and evidence of mild systemic inflammation (high-sensitivity C-reactive protein [hs-CRP] between 2 and 5 mg/L) were randomly allocated to receive either 220.5 mg of cis-palmitoleic acid (n = 30) or an identical capsule with placebo (1000 mg of medium chain triglycerides, n = 30) once per day for 30 days. Participants were asked to maintain their current diet. Serum lipids and hs-CRP were drawn at baseline and study completion.

RESULTS

At 30 days, there were significant mean (95% confidence interval [CI]) reductions in CRP (-1.9 [-2.3 to -1.4] mg/L), triglyceride (-30.2 [-40.2 to -25.3] mg/dL), and low-density lipoprotein (LDL) (-8.9 [-12.0 to -5.8] mg/dL), and a significant increase in high-density lipoprotein (HDL) (2.4 [1.5, 3.3] mg/dL) in the intervention group compared with control. These changes equated to 44%, 15%, and 8% reductions in CRP, triglyceride, and LDL respectively, and a 5% increase in HDL compared with control.

CONCLUSIONS

Purified palmitoleic acid may be useful in the treatment of hypertriglyceridemia with the beneficial added effects of decreasing LDL and hs-CRP and raising HDL. Further study is needed to elucidate mechanisms and establish appropriate human doses.

Palmitoleic acid (n-7) attenuates the immunometabolic disturbances caused by a high-fat diet independently of PPARα

Palmitoleic acid (PMA) has anti-inflammatory and antidiabetic activities. Here we tested whether these effects of PMA on glucose homeostasis and liver inflammation, in mice fed with high-fat diet (HFD), are PPAR-α dependent. C57BL6 wild-type (WT) and PPAR-α-knockout (KO) mice fed with a standard diet (SD) or HFD for 12 weeks were treated after the 10th week with oleic acid (OLA, 300 mg/kg of b.w.) or PMA 300 mg/kg of b.w. Steatosis induced by HFD was associated with liver inflammation only in the KO mice, as shown by the increased hepatic levels of IL1-beta, IL-12, and TNF-α; however, the HFD increased the expression of TLR4 and decreased the expression of IL1-Ra in both genotypes. Treatment with palmitoleate markedly attenuated the insulin resistance induced by the HFD, increased glucose uptake and incorporation into muscle in vitro, reduced the serum levels of AST in WT mice, decreased the hepatic levels of IL1-beta and IL-12 in KO mice, reduced the expression of TLR-4 and increased the expression of IL-1Ra in WT mice, and reduced the phosphorylation of NF 𝜅B (p65) in the livers of KO mice. We conclude that palmitoleate attenuates diet-induced insulin resistance, liver inflammation, and damage through mechanisms that do not depend on PPAR-α.

Calmodulin dependent protein kinase II activation by exercise regulates saturated & unsaturated fatty acids and improves some metabolic syndrome markers

AIMS

Activation of Calmodulin dependent protein kinase (CaMK)-II by exercise has a plethora of benefits in health. Fatty acids play a pivotal role in the pathogenesis of metabolic syndrome (MetS). Prevention of MetS and treatment of its main characteristics are very significant to fight against type 2 diabetes. CaMKII activation in the regulation of saturated and unsaturated fatty acids in relation to type 2 diabetes and MetS has not been studied, which became the focus of this present study.

MAIN METHODS

Using Gas chromatography-Mass spectrometry, we investigated saturated fatty acids and unsaturated fatty acids. Quantitative real time PCR was also used to assess the gene expression.

KEY FINDINGS

Results indicate that both palmitoleic acid and oleic acid which are monounsaturated fatty acids were increased in response to CaMKII activation. On the other hand, myristic acid and palmitic acid which are saturated fatty acids known to increase the risk factors of MetS and type 2 diabetes were decreased by exercise induction of CaMKII. Conversely, lauric acid also a saturated fatty acid was increased in response to CaMKII activation by exercise. This fatty acid is known to have beneficial effects in alleviating symptoms of both type 2 diabetes and MetS.

SIGNIFICANCE

According to our knowledge, this is the first study to show that CaMKII activation by exercise regulates fatty acids essential in type 2 diabetes and MetS. CaMKII can be an avenue of designing novel therapeutic drugs in the management and treatment of type 2 diabetes and MetS.

Fatty acid elongase-5 (Elovl5) regulates hepatic triglyceride catabolism in obese C57BL/6J mice

Nonalcoholic fatty liver disease is a major public health concern in the obese and type 2 diabetic populations. The high-fat lard diet induces obesity and fatty liver in C57BL/6J mice and suppresses expression of the PPAR-target gene, FA elongase 5 (Elovl5). Elovl5 plays a key role in MUFA and PUFA synthesis. Increasing hepatic Elovl5 activity in obese mice lowered hepatic TGs and endoplasmic reticulum stress markers (X-box binding protein 1 and cAMP-dependent transcription factor 6α) and increased TG catabolism and fatty acyl carnitines. Increased hepatic Elovl5 activity did not increase hepatic capacity for β-oxidation. Elovl5 effects on hepatic TG catabolism were linked to increased protein levels of adipocyte TG lipase (ATGL) and comparative gene identification 58 (CGI58). Elevated hepatic Elovl5 activity also induced the expression of some (pyruvate dehydrogenase kinase 4 and fibroblast growth factor 21), but not other cytochrome P450 4A10 (CYP4A10), PPAR-target genes. FA products of Elovl5 activity increased ATGL, but not CGI58, mRNA through PPARβ-dependent mechanisms in human HepG2 cells. Treatment of mouse AML12 hepatocytes with the PPARβ agonist (GW0742) decreased (14)C-18:2,n-6 in TGs but did not affect β-oxidation. These studies establish that Elovl5 activity regulates hepatic levels of FAs controlling PPARβ activity, ATGL expression, and TG catabolism, but not FA oxidation.

Modeling progressive non-alcoholic fatty liver disease in the laboratory mouse

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in the world and its prevalence is rising. In the absence of disease progression, fatty liver poses minimal risk of detrimental health outcomes. However, advancement to non-alcoholic steatohepatitis (NASH) confers a markedly increased likelihood of developing severe liver pathologies, including fibrosis, cirrhosis, organ failure, and cancer. Although a substantial percentage of NAFLD patients develop NASH, the genetic and molecular mechanisms driving this progression are poorly understood, making it difficult to predict which patients will ultimately develop advanced liver disease. Deficiencies in mechanistic understanding preclude the identification of beneficial prognostic indicators and the development of effective therapies. Mouse models of progressive NAFLD serve as a complementary approach to the direct analysis of human patients. By providing an easily manipulated experimental system that can be rigorously controlled, they facilitate an improved understanding of disease development and progression. In this review, we discuss genetically- and chemically-induced models of NAFLD that progress to NASH, fibrosis, and liver cancer in the context of the major signaling pathways whose disruption has been implicated as a driving force for their development. Additionally, an overview of nutritional models of progressive NAFLD is provided.

Characterization of newly isolated oleaginous yeasts - Cryptococcus podzolicus, Trichosporon porosum and Pichia segobiensis

The yeast strains Cryptococcus podzolicus, Trichosporon porosum and Pichia segobiensis were isolated from soil samples and identified as oleaginous yeast strains beneficial for the establishment of microbial production processes for sustainable lipid production suitable for several industrial applications. When cultured in bioreactors with glucose as the sole carbon source C. podzolicus yielded 31.8% lipid per dry biomass at 20°C, while T. porosum yielded 34.1% at 25°C and P. segobiensis 24.6% at 25°C. These amounts correspond to lipid concentrations of 17.97 g/L, 17.02 g/L and 12.7 g/L and volumetric productivities of 0.09 g/Lh, 0.1 g/Lh and 0.07 g/Lh, respectively. During the culture of C. podzolicus 30 g/l gluconic acid was detected as by-product in the culture broth and 12 g/L gluconic acid in T. porosum culture. The production of gluconic acid was eliminated for both strains when glucose was substituted by xylose as the carbon source. Using xylose lipid yields were 11.1 g/L and 13.9 g/L, corresponding to 26.8% and 33.4% lipid per dry biomass and a volumetric productivity of 0.07 g/Lh and 0.09 g/Lh, for C. podzolicus and T. porosum respectively. The fatty acid profile analysis showed that oleic acid was the main component (39.6 to 59.4%) in all three strains and could be applicable for biodiesel production. Palmitic acid (18.4 to 21.1%) and linolenic acid (7.5 to 18.7%) are valuable for cosmetic applications. P. segobiensis had a considerable amount of palmitoleic acid (16% content) and may be suitable for medical applications.

Nutritional profile of phytococktail from trans-Himalayan plants

We estimated the nutritive value, vitamin content, amino acid composition, fatty acid content, and mineral profile of a phytococktail comprising sea buckthorn (Hippophae rhamnoides), apricot (Prunus armeniaca), and roseroot (Rhodiola imbricata) from trans-Himalaya. The free vitamin forms in the phytococktail were determined by rapid resolution liquid chromatography/tandem mass spectrometry (RRLC-MS/MS). Vitamin E and B-complex vitamins were detected as the principle vitamins. Reversed-phase high performance liquid chromatography (RP-HPLC) with pre-column derivatization was used for identification and quantification of amino acids. Eight essential and eleven non-essential amino acids were quantified, and the content ranged between 76.33 and 9485.67 µg/g. Among the essential amino acids, L-methionine, L-phenylalanine, L-lysine, L-leucine, and L-histidine were found to be the dominant contributors. We also quantified the fatty acids in the phytococktail by using gas chromatography coupled with a flame ionization detector (GC-FID) with fatty acid methyl esters (FAMEs) derivatization. The analysis revealed the presence of 4 major fatty acids contributing to the total lipid content. Palmitic acid was found to be the rich source of saturated fatty acid (SFA) and constituted ∼31% of the total lipid content. Among the unsaturated fatty acids (UFAs), palmitoleic acid (43.47%), oleic acid (20.89%), and linoleic acid (4.31%) were prominent. The mineral profiling was carried out by inductively coupled plasma optical emission spectrometer (ICP-OES), and it was found to contain a number of important dietary mineral elements. The harsh climatic conditions, difficult terrain, and logistic constraints at high altitude regions of Indian trans-Himalayan cold desert lead to the scarcity of fresh fruits and vegetables. Therefore, the source of multiple vitamins, essential amino acids, fatty acids, and dietary minerals from the phytococktail would provide great health benefit in the stressful environment and could be used as a high value nutritional supplement.

Long-chain free fatty acid profiling analysis by liquid chromatography-mass spectrometry in mouse treated with peroxisome proliferator-activated receptor α agonist

A change in the free fatty acid (FFA) profile reflects an alteration in the lipid metabolism of peripheral tissue. A high-throughput quantitative analysis method for individual FFAs therefore needs to be established. We report here an optimized LC-MS assay for a high-throughput and high-sensitivity analysis of the 10 major long-chain FFAs in mouse plasma and liver. This assay enables quantification of individual FFAs by using trace amounts of samples (2 µL of plasma and 10 mg of liver tissue). We apply this method to analyze the FFA profile of plasma and liver samples from an obese mouse model treated with bezafibrate, the peroxisome proliferator-activated receptor α (PPARα) agonist, and show a change in the FFA profile, particularly in the palmitoleic and oleic acid contents. This assay is useful for quantifying individual FFAs and helpful for monitoring the condition of lipid metabolism.

Palmitoleic acid (n-7) increases white adipocyte lipolysis and lipase content in a PPARα-dependent manner

We investigated whether palmitoleic acid, a fatty acid that enhances whole body glucose disposal and suppresses hepatic steatosis, modulates triacylglycerol (TAG) metabolism in adipocytes. For this, both differentiated 3T3-L1 cells treated with either palmitoleic acid (16:1n7, 200 μM) or palmitic acid (16:0, 200 μM) for 24 h and primary adipocytes from wild-type or PPARα-deficient mice treated with 16:1n7 (300 mg·kg(-1)·day(-1)) or oleic acid (18:1n9, 300 mg·kg(-1)·day(-1)) by gavage for 10 days were evaluated for lipolysis, TAG, and glycerol 3-phosphate synthesis and gene and protein expression profile. Treatment of differentiated 3T3-L1 cells with 16:1n7, but not 16:0, increased basal and isoproterenol-stimulated lipolysis, mRNA levels of adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL) and protein content of ATGL and pSer(660)-HSL. Such increase in lipolysis induced by 16:1n7, which can be prevented by pharmacological inhibition of PPARα, was associated with higher rates of PPARα binding to DNA. In contrast to lipolysis, both 16:1n7 and 16:0 increased fatty acid incorporation into TAG and glycerol 3-phosphate synthesis from glucose without affecting glyceroneogenesis and glycerokinase expression. Corroborating in vitro findings, treatment of wild-type but not PPARα-deficient mice with 16:1n7 increased primary adipocyte basal and stimulated lipolysis and ATGL and HSL mRNA levels. In contrast to lipolysis, however, 16:1n7 treatment increased fatty acid incorporation into TAG and glycerol 3-phosphate synthesis from glucose in both wild-type and PPARα-deficient mice. In conclusion, palmitoleic acid increases adipocyte lipolysis and lipases by a mechanism that requires a functional PPARα.

Effects of sea buckthorn and bilberry on serum metabolites differ according to baseline metabolic profiles in overweight women: a randomized crossover trial

BACKGROUND

Berries are associated with health benefits. Little is known about the effect of baseline metabolome on the overall metabolic responses to berry intake.

OBJECTIVE

We studied the effects of berries on serum metabolome.

DESIGN

Eighty overweight women completed this randomized crossover study. During the interventions of 30 d, subjects consumed dried sea buckthorn berries (SBs), sea buckthorn oil (SBo), sea buckthorn phenolics ethanol extract mixed with maltodextrin (SBe+MD) (1:1), or frozen bilberries. Metabolic profiles were quantified from serum samples by using (1)H nuclear magnetic resonance spectroscopy.

RESULTS

All interventions induced a significant (P < 0.001-0.003) effect on the overall metabolic profiles. The effect was observed both in participants who had a metabolic profile that reflected higher cardiometabolic risk at baseline (group B: P = 0.001-0.008) and in participants who had a lower-risk profile (group A: P < 0.001-0.009). Although most of the changes in individual metabolites were not statistically significant after correction for multiplicity, clear trends were observed. SB-induced effects were mainly on serum triglycerides and very-low-density lipoprotein (VLDL) and its subclasses, which decreased in metabolic group B. SBo induced a decreasing trend in serum total, intermediate-density lipoprotein (IDL), and low-density lipoprotein (LDL) cholesterol and subfractions of IDL and LDL in group B. During the SBe+MD treatment, VLDL fractions and serum triglycerides increased. Bilberries caused beneficial changes in serum lipids and lipoproteins in group B, whereas the opposite was true in group A.

CONCLUSION

Berry intake has overall metabolic effects, which depend on the cardiometabolic risk profile at baseline. This trial was registered at clinicaltrials.gov as NCT01860547.

A review of the phytochemistry and pharmacological activities of raphani semen

The dried ripe seed of Raphanus sativus L., commonly known as radish seed (or Raphani Semen), is used as traditional Chinese medicine (TCM) to treat constipation, chronic tracheitis, and hypertension. The major active compounds in Raphani Semen are alkaloids, glucosinolates, brassinosteroids, and flavonoids. Fatty acids are its main nutritional contents. Raphani Semen has been demonstrated to have beneficial effects on hypertension, obesity, diabetes mellitus, constipation, and cough. So far, there is no report about the adverse/toxic effects of this herb on humans. However, Raphani Semen processed by roasting was reported to exhibit some adverse effects on mice. Additionally, erucic acid, the main fatty acid in Raphani Semen, was shown to enhance the toxicity of doxorubicin. Thus, Raphani Semen has a potential risk of causing toxicity and drug interaction. In summary, Raphani Semen is a valuable TCM herb with multiple pharmacological effects. More studies on Raphani Semen could help better understand its pharmacological mechanisms so as to provide clear scientific evidence to explain its traditional uses, to identify its therapeutic potential on other diseases, and to understand its possible harmful effects.

Fatty acids regulation of inflammatory and metabolic genes

PURPOSE OF REVIEW

Fatty acids influence human health and diseases in various ways. In recent years, much work has been carried out to elucidate the mechanisms by which dietary fatty acids control short-term and long-term cellular functions. We have reviewed herein the most recent studies on modulation of gene expression by fatty acids. A number of genes respond to transcription factors and present a transcription factor response element in their promoter regions. Fatty acids may exert their effects on metabolism by regulating gene transcription via transcription factors. Understanding how fatty acids control expression of metabolic genes is a promising strategy to be investigated by aiming to treat metabolic diseases such as insulin resistance, obesity, and type 2 diabetes mellitus.

RECENT FINDINGS

Fatty acids exert many of their biological effects through the modulation of the activity of transcription factors, such as sterol regulatory element-binding proteins, peroxisome proliferator-activated receptors, and liver X receptors.

SUMMARY

Fatty acid action through transcription factors controls the expression of several inflammatory and metabolic genes.

De novo lipogenesis in human fat and liver is linked to ChREBP-β and metabolic health

Clinical interest in de novo lipogenesis has been sparked by recent studies in rodents demonstrating that de novo lipogenesis specifically in white adipose tissue produces the insulin-sensitizing fatty acid palmitoleate. By contrast, hepatic lipogenesis is thought to contribute to metabolic disease. How de novo lipogenesis in white adipose tissue versus liver is altered in human obesity and insulin resistance is poorly understood. Here we show that lipogenic enzymes and the glucose transporter-4 are markedly decreased in white adipose tissue of insulin-resistant obese individuals compared with non-obese controls. By contrast, lipogenic enzymes are substantially upregulated in the liver of obese subjects. Bariatric weight loss restored de novo lipogenesis and glucose transporter-4 gene expression in white adipose tissue. Notably, lipogenic gene expression in both white adipose tissue and liver was strongly linked to the expression of carbohydrate-responsive element-binding protein-β and to metabolic risk markers. Thus, de novo lipogenesis predicts metabolic health in humans in a tissue-specific manner and is likely regulated by glucose-dependent carbohydrate-responsive element-binding protein activation.

Reducing saturated fatty acids in Arabidopsis seeds by expression of a Caenorhabditis elegans 16:0-specific desaturase

Plant oilseeds are a major source of nutritional oils. Their fatty acid composition, especially the proportion of saturated and unsaturated fatty acids, has important effects on human health. Because intake of saturated fats is correlated with the incidence of cardiovascular disease and diabetes, a goal of metabolic engineering is to develop oils low in saturated fatty acids. Palmitic acid (16:0) is the most abundant saturated fatty acid in the seeds of many oilseed crops and in Arabidopsis thaliana. We expressed FAT-5, a membrane-bound desaturase cloned from Caenorhabditis elegans, in Arabidopsis using a strong seed-specific promoter. The FAT-5 enzyme is highly specific to 16:0 as substrate, converting it to 16:1∆9; expression of fat-5 reduced the 16:0 content of the seed by two-thirds. Decreased 16:0 and elevated 16:1 levels were evident both in the storage and membrane lipids of seeds. Regiochemical analysis of phosphatidylcholine showed that 16:1 was distributed at both positions on the glycerolipid backbone, unlike 16:0, which is predominately found at the sn-1 position. Seeds from a plant line homozygous for FAT-5 expression were comparable to wild type with respect to seed set and germination, while oil content and weight were somewhat reduced. These experiments demonstrate that targeted heterologous expression of a desaturase in oilseeds can reduce the level of saturated fatty acids in the oil, significantly improving its nutritional value.

Spontaneous onset of nonalcoholic steatohepatitis and hepatocellular carcinoma in a mouse model of metabolic syndrome

Metabolic syndrome is a worldwide healthcare issue and a dominant risk factor for the development of incurable diseases that affect the entire body. The hepatic manifestations of this syndrome include nonalcoholic fatty liver disease (NAFLD) and its progressive variant nonalcoholic steatohepatitis (NASH). The basic pathogenesis of NAFLD/NASH remains controversial because it is difficult to clarify the disease process of NASH on the basis of metabolic syndrome alone. To determine the pathogenesis and effective treatment, an excellent animal model of NASH is required. Tsumura Suzuki obese diabetes (TSOD) male mice spontaneously develop diabetes mellitus, obesity, glucosuria, hyperglycemia, and hyperinsulinemia without any special treatments such as gene manipulation. In this study, we examined the histopathological characteristics of visceral fat and liver of 56 male TSOD mice aged 4-17 months and 9 male Tsumura Suzuki non-obesity (control) mice aged 6-12 months. In the visceral fat, enlargement of adipocytes and perivascular and pericapsular CD8-positive lymphoid aggregation were observed in 4-month-old mice. Abnormal expression of tumor necrosis factor-α, interleukin-6, and lipid peroxidation endo products was observed in macrophages. In the liver, microvesicular steatosis, hepatocellular ballooning, and Mallory bodies were observed in 4-month-old mice, with severity worsening with increasing time. These pathological findings in the liver mimic those seen in patients with NASH. Interestingly, small liver nodules with high cellularity and absence of portal tracts were frequently observed after 12 months. Most of them showed nuclear and structural atypia, and mimicked human hepatocellular carcinoma. The degree of steatosis in the non-tumor portions of the liver improved when the liver nodules developed. These findings were not observed in control mice. Here, we report that TSOD male mice spontaneously developed NAFLD without any special treatment, and that these mice are a valuable model for assessing NASH and NASH carcinogenesis owing to metabolic syndrome.

Oral administration of omega-7 palmitoleic acid induces satiety and the release of appetite-related hormones in male rats

We have analyzed the effect of palmitoleic acid on short-term food intake in male rats. Administration of omega-7 palmitoleic acid by oral gavage significantly decreased food intake compared to palmitic acid, omega-9 oleic acid, or a vehicle control. Palmitoleic acid exhibited a dose-dependent effect in this context and did not cause general malaise. A triglyceride form of palmitoleate also decreased food intake, whereas olive oil, which is rich in oleic acid, did not. Palmitoleic acid accumulated within the small intestine in a dose-dependent fashion and elevated levels of the satiety hormone cholecystokinin (CCK). Both protein and mRNA levels of CCK were affected in this context. The suppression of food intake by palmitoleic acid was attenuated by intravenous injection of devazepide, a selective peripheral CCK receptor antagonist. Palmitoleic acid did not alter the expression of peroxisome proliferator-activated receptor alpha (PPARα) target genes, and a PPARα antagonist did not affect palmitoleic acid-induced satiety. This suggests that the PPARα pathway might not be involved in suppressing food intake in response to palmitoleic acid. We have shown that orally administered palmitoleic acid induced satiety, enhanced the release of satiety hormones in rats.

Effects of adipocyte lipoprotein lipase on de novo lipogenesis and white adipose tissue browning

Efficient storage of dietary and endogenous fatty acids is a prerequisite for a healthy adipose tissue function. Lipoprotein lipase (LPL) is the master regulator of fatty acid uptake from triglyceride-rich lipoproteins. In addition to LPL-mediated fatty acid uptake, adipocytes are able to synthesize fatty acids from non-lipid precursor, a process called de novo lipogenesis (DNL). As the physiological relevance of fatty acid uptake versus DNL for brown and white adipocyte function remains unclear, we studied the role of adipocyte LPL using adipocyte-specific LPL knockout animals (aLKO). ALKO mice displayed a profound increase in DNL-fatty acids, especially palmitoleate and myristoleate in brown adipose tissue (BAT) and white adipose tissue (WAT) depots while essential dietary fatty acids were markedly decreased. Consequently, we found increased expression in adipose tissues of genes encoding DNL enzymes (Fasn, Scd1, and Elovl6) as well as the lipogenic transcription factor carbohydrate response element binding protein-β. In a high-fat diet (HFD) study aLKO mice were characterized by reduced adiposity and improved plasma insulin and adipokines. However, neither glucose tolerance nor inflammatory markers were ameliorated in aLKO mice compared to controls. No signs of increased BAT activation or WAT browning were detected in aLKO mice either on HFD or after 1 week of β3-adrenergic stimulation using CL316,243. We conclude that despite a profound increase in DNL-derived fatty acids, proposed to be metabolically favorable, aLKO mice are not protected from metabolic disease per se. In addition, induction of DNL alone is not sufficient to promote browning of WAT. This article is part of a Special Issue entitled Brown and White Fat: From Signaling to Disease.

Elovl5 regulates the mTORC2-Akt-FOXO1 pathway by controlling hepatic cis-vaccenic acid synthesis in diet-induced obese mice

Elevated hepatic expression of fatty acid elongase-5 (Elovl5) induces FoxO1 phosphorylation, lowers FoxO1 nuclear content, and suppresses expression of genes involved in gluconeogenesis (GNG). In this report, we define the molecular and metabolic basis of Elovl5 control of FoxO1 phosphorylation. Adenoviral-mediated (Ad-Elovl5) induction of hepatic Elovl5 in diet-induced obese, glucose-intolerant mice and HepG2 cells increased the phosphorylation of Akt2-S(473) [mammalian target of rapamycin complex-2 (mTORC2) site], but not Akt2-T(308) (PDK1 site). The Akt2 inhibitor Akti1/2 blocked Elovl5 induction of FoxO1-S(256) phosphorylation in HepG2 cells. Elevated Elovl5 activity in liver and HepG2 cells induced rictor mRNA, rictor protein, and rictor-mTOR interaction, whereas rictor knockdown (siRNA) attenuated Elovl5 induction of Akt2-S(473) and FoxO1-S(256) phosphorylation in HepG2 cells. FA analysis revealed that the abundance of cis-vaccenic acid (18:1,n-7) was increased in livers of obese mice and HepG2 cells following Ad-Elovl5 infection. Treating HepG2 cells with Elovl5 substrates established that palmitoleic acid (16:1,n-7), but not γ-linolenic acid (18:3,n-6), induced rictor protein, Akt-S(473), and FoxO1-S(256) phosphorylation. Inhibition of FA elongation blocked 16:1,n-7 but not 18:1,n-7 induction of rictor protein and Akt-S(473) and FoxO1-S(256) phosphorylation. These results establish a novel link between Elovl5-mediated synthesis of 18:1,n-7 and GNG through the control of the mTORC2-Akt-FoxO1 pathway.

Plasma phospholipid concentration of cis-palmitoleic acid and risk of heart failure

BACKGROUND

Although plasma palmitoleic acid has been positively associated with blood pressure, inflammation, and insulin resistance, its association with heart failure has not been investigated. We assessed whether plasma phospholipid cis-palmitoleic acid was associated with heart failure risk.

METHODS AND RESULTS

This ancillary study of the Physicians' Health Study used a risk set sampling method to select 788 matched pairs. For each case of incident heart failure, we randomly selected a control among subjects that were free of heart failure and alive at the time of index case diagnosis and matched on age, year of birth, race, and time of blood collection. Plasma phospholipid fatty acids were measured using gas chromatography. Heart failure was ascertained using annual follow-up questionnaire and validated in a subsample. In a multivariable conditional logistic regression, odds ratios (95% CI) for heart failure were 1.0 (ref), 1.06 (0.75-1.48), 1.20 (0.85-1.68), and 1.58 (1.11-2.25) across consecutive quartiles of cis-palmitoleic acid (P for trend 0.009). Each SD increase in plasma cis-palmitoleic acid was associated with 17% higher odds of heart failure (95% CI: 2% to 33%) in a multivariable model. In a secondary analysis, each SD increase of log-stearoyl-coA desaturase activity (16:1n-7/16:0 ratio) was positively associated with the risk of heart failure (odds ratio: 1.14 [95% CI: 1.00 to 1.29]), whereas oleic acid and cis-vaccenic acid concentrations were not related to heart failure risk.

CONCLUSIONS

Our data showed a positive association between plasma phospholipid cis- palmitoleic acid and heart failure risk in male physicians.

Red blood cell membrane concentration of cis-palmitoleic and cis-vaccenic acids and risk of coronary heart disease

Although previous studies have suggested associations between plasma palmitoleic acid and coronary heart disease (CHD) risk factors, including blood pressure, inflammation, and insulin resistance, little is known about the relation of palmitoleic acid and CHD. This ancillary study of the Physicians' Health Study was designed to examine whether red blood cell (RBC) membrane cis-palmitoleic acid and cis-vaccenic acid-2 fatty acids that can be synthesized endogenously-are associated with CHD risk. We used a risk set sampling method to prospectively select 1,000 incident CHD events and 1,000 matched controls. RBC membrane fatty acids were measured using gas chromatography. The CHD cases were ascertained using an annual follow-up questionnaire and validated by an End Point Committee through a review of the medical records. In a conditional logistic regression analysis adjusting for demographics, anthropometric, lifestyle factors, and co-morbidity, the odds ratios and 95% confidence intervals (CIs) for CHD were 1.0 (referent), 1.29 (95% CI 0.95 to 1.75), 1.08 (95% CI 0.78 to 1.51), 1.25 (95% CI 0.90 to 1.75), and 1.48 (95% CI 1.03 to 2.14) across consecutive quintiles of RBC membrane cis-palmitoleic acid (p for trend = 0.041). The odds ratio associated with each SD higher RBC membrane cis-palmitoleic acid level was 1.19 (95% CI 1.06 to 1.35) in a multivariate-adjusted model. Finally, RBC membrane cis-vaccenic acid was inversely associated with CHD risk (odds ratio 0.79, 95% CI 0.69 to 0.91, per SD increase). In conclusion, our data showed a positive association between RBC membrane cis-palmitoleic acid and CHD risk in male physicians. Furthermore, RBC membrane cis-vaccenic acid was inversely related to CHD.

Associations of fatty acids in cerebrospinal fluid with peripheral glucose concentrations and energy metabolism

Rodent experiments have emphasized a role of central fatty acid (FA) species, such as oleic acid, in regulating peripheral glucose and energy metabolism. Thus, we hypothesized that central FAs are related to peripheral glucose regulation and energy expenditure in humans. To test this we measured FA species profiles in cerebrospinal fluid (CSF) and plasma of 32 individuals who stayed in our clinical inpatient unit for 6 days. Body composition was measured by dual energy X-ray absorptiometry and glucose regulation by an oral glucose test (OGTT) followed by measurements of 24 hour (24EE) and sleep energy expenditure (SLEEP) as well as respiratory quotient (RQ) in a respiratory chamber. CSF was obtained via lumbar punctures; FA concentrations were measured by liquid chromatography/mass spectrometry. As expected, FA concentrations were higher in plasma compared to CSF. Individuals with high concentrations of CSF very-long-chain saturated FAs had lower rates of SLEEP. In the plasma moderate associations of these FAs with higher 24EE were observed. Moreover, CSF monounsaturated long-chain FA (palmitoleic and oleic acid) concentrations were associated with lower RQs and lower glucose area under the curve during the OGTT. Thus, FAs in the CSF strongly correlated with peripheral metabolic traits. These physiological parameters were most specific to long-chain monounsaturated (C16∶1, C18∶1) and very-long-chain saturated (C24∶0, C26∶0) FAs. Conclusions: Together with previous animal experiments these initial cross-sectional human data indicate that central FA species are linked to peripheral glucose and energy homeostasis.

Palmitoleate induces hepatic steatosis but suppresses liver inflammatory response in mice

The interaction between fat deposition and inflammation during obesity contributes to the development of non-alcoholic fatty liver disease (NAFLD). The present study examined the effects of palmitoleate, a monounsaturated fatty acid (16∶1n7), on liver metabolic and inflammatory responses, and investigated the mechanisms by which palmitoleate increases hepatocyte fatty acid synthase (FAS) expression. Male wild-type C57BL/6J mice were supplemented with palmitoleate and subjected to the assays to analyze hepatic steatosis and liver inflammatory response. Additionally, mouse primary hepatocytes were treated with palmitoleate and used to analyze fat deposition, the inflammatory response, and sterol regulatory element-binding protein 1c (SREBP1c) activation. Compared with controls, palmitoleate supplementation increased the circulating levels of palmitoleate and improved systemic insulin sensitivity. Locally, hepatic fat deposition and SREBP1c and FAS expression were significantly increased in palmitoleate-supplemented mice. These pro-lipogenic events were accompanied by improvement of liver insulin signaling. In addition, palmitoleate supplementation reduced the numbers of macrophages/Kupffer cells in livers of the treated mice. Consistently, supplementation of palmitoleate decreased the phosphorylation of nuclear factor kappa B (NF-κB, p65) and the expression of proinflammatory cytokines. These results were recapitulated in primary mouse hepatocytes. In terms of regulating FAS expression, treatment of palmitoleate increased the transcription activity of SREBP1c and enhanced the binding of SREBP1c to FAS promoter. Palmitoleate also decreased the phosphorylation of NF-κB p65 and the expression of proinflammatory cytokines in cultured macrophages. Together, these results suggest that palmitoleate acts through dissociating liver inflammatory response from hepatic steatosis to play a unique role in NAFLD.

The role of endoplasmic reticulum in hepatic lipid homeostasis and stress signaling

The endoplasmic reticulum (ER) is a critical site of protein, lipid, and glucose metabolism, lipoprotein secretion, and calcium homeostasis. Many of the sensing, metabolizing, and signaling mechanisms for these pathways exist within or on the ER membrane domain. Here, we review the cellular functions of ER, how perturbation of ER homeostasis contributes to metabolic dysregulation and potential causative mechanisms of ER stress in obesity, with a particular focus on lipids, metabolic adaptations of ER, and the maintenance of its membrane homeostasis. We also suggest a conceptual framework of metabolic roundabout to integrate key mechanisms of insulin resistance and metabolic diseases.

Effects of rice bran oil on the blood lipids profiles and insulin resistance in type 2 diabetes patients

The aim of this study was to investigate the influence of rice bran oil consumption on plasma lipids and insulin resistance in patients with type 2 diabetes. Thirty-five patients with type 2 diabetes were randomly assigned to a placebo group or a rice bran oil group. The placebo group consumed 250 mL soybean oil-modified milk (18 g soybean oil) daily for 5 weeks, and the rice bran oil group consumed 250 mL rice bran oil modified milk (18 g rice bran oil) daily for 5 weeks. At week 0 and week 5, anthropometric measurements, hematology tests, and an oral-glucose-tolerance test were conducted. The results showed that the homeostasis model assessment index of insulin resistance, the area under the curve for postprandial serum insulin, and serum low-density-lipoprotein cholesterol concentrations increased significantly in the placebo group. In the rice bran oil group, fasting and 2-h postprandial blood glucose concentrations and the area under the curve for postprandial plasma glucose increased significantly; however, total serum cholesterol and low-density-lipoprotein cholesterol concentrations decreased significantly. However, the homeostasis model assessment index of insulin resistance was not significantly different. Consumption of 18 g rice bran oil modified milk daily for 5 weeks significantly decreased total serum cholesterol concentrations and tended to decrease low-density-lipoprotein cholesterol concentrations in patients with type 2 diabetes. However, no significant influence on insulin resistance was observed.