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

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

A reduction of skeletal muscle DHA content does not result in impaired whole body glucose tolerance or skeletal muscle basal insulin signaling in otherwise healthy mice.

Delta-6 desaturase (D6D), encoded by the Fads2 gene, catalyzes the first step in the conversion of α-linolenic acid to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The ablation of D6D in whole body Fads2-/- knockout (KO) mice results in an inability to endogenously produce EPA and DHA. Evidence supports a beneficial role for EPA and DHA on insulin-stimulated glucose disposal in skeletal muscle in the context of a metabolic challenge; however, it is unknown how low EPA and DHA levels impact skeletal muscle fatty acid composition and insulin signaling in a healthy context. The objective of this study was to examine the impact of ablating the endogenous production of EPA and DHA on skeletal muscle fatty acid composition, whole body glucose and insulin tolerance, and a key marker of skeletal muscle insulin signaling (pAkt). Male C57BL/6J wild-type (WT), Fads2+/- heterozygous, and Fads2-/- KO mice were fed a low-fat diet (16% kcal from fat) modified to contain either 7% w/w lard or 7% w/w flaxseed for 21 wk. No differences in total phospholipid (PL), triacylglycerol, or reactive lipid content were observed between genotypes. As expected, KO mice on both diets had significantly less DHA content in skeletal muscle PL. Despite this, KO mice did not have significantly different glucose or insulin tolerance compared with WT mice on either diet. Basal pAktSer473 was not significantly different between the genotypes within each diet. Ultimately, this study shows for the first time, to our knowledge, that the reduction of DHA in skeletal muscle is not necessarily detrimental to glucose homeostasis in otherwise healthy animals.NEW & NOTEWORTHY Skeletal muscle is the primary location of insulin-stimulated glucose uptake. EPA and DHA supplementation has been observed to improve skeletal muscle insulin-stimulated glucose uptake in models of metabolic dysfunction. Fads2-/- knockout mice cannot endogenously produce long-chain n-3 polyunsaturated fatty acids. Our results show that the absence of DHA in skeletal muscle is not detrimental to whole body glucose homeostasis in healthy mice.

Interaction among dietary n-3 and n-6 polyunsaturated fatty acid intake, fatty acid desaturase 2 genetic variants, and low-density lipoprotein cholesterol levels in type 2 diabetes patients.

AIMS/INTRODUCTION: Fatty acid desaturase (FADS) genetic polymorphisms are strongly correlated with the risk of dyslipidemia and cardiovascular disease. In this study, we examined the impact of FADS1 and FADS2 genetic variants on plasma lipid status, and assessed interactions between FADS genetic polymorphisms and plasma n-3/n-6 fatty acids regarding lipid status within a population of 816 Taiwanese patients with type 2 diabetes. MATERIALS AND METHODS: Selected tag single-nucleotide polymorphisms (FADS1 rs174546 [T/C]; FADS2 rs174602 [A/G] and rs2072114 [A/G]) were genotyped (n = 816). RESULTS: The distribution of genotypes were compared with reports publicly available in the Genome Aggregation Database for East Asian populations (https://gnomad.broadinstitute.org). In the subgroup of patients not taking lipid-lowering medications (n = 192), we observed that the G allele of FADS2 rs174602 was statistically significantly correlated with lower low-density lipoprotein cholesterol (LDL-C) concentrations (P = 0.001), whereas the G allele of rs2072114 was marginally associated with LDL-C concentrations (P = 0.091). Using a general linear model adjusted for confounding factors, statistically significant interactions (P = 0.016) between single-nucleotide polymorphisms in rs2072114 and a low alpha-linolenic acid (18:3n-3)/linoleic acid (18:2n-6) ratio; the G allele correlated with lower LDL-C levels among individuals with a low alpha-linolenic acid/linoleic acid ratio. Interaction between rs174602 single-nucleotide polymorphisms and low alpha-linolenic acid/linoleic acid values on LDL-C was only marginally significant (P = 0.063). CONCLUSIONS: Our results show the role of n-3/n-6 dietary polyunsaturated fatty acids in modifying the effects of genetic susceptibility on lipoprotein concentrations in patients with type 2 diabetes. Our findings highlight the potential of interventions with dietary polyunsaturated fatty acids regarding developing individualized prevention strategies for type 2 diabetes presenting with co-occurring dyslipidemia and cardiovascular diseases.

Metabolomics and Proteomics Characterizing Hepatic Reactions to Dietary Linseed Oil in Duck.

The imbalance in polyunsaturated fatty acid (PUFA) composition in human food is ubiquitous and closely related to obesity and cardiovascular diseases. The development of n-3 PUFA-enriched poultry products is of great significance for optimizing fatty acid composition. This study aimed to improve our understanding of the effects of dietary linseed oil on hepatic metabolism using untargeted metabolomics and 4D label-free proteome analysis. A total of 91 metabolites and 63 proteins showed differences in abundance in duck livers between the high linseed oil and control groups. Pathway analysis revealed that the biosynthesis of unsaturated fatty acids, linoleic acid, glycerophospholipid, and pyrimidine metabolisms were significantly enriched in ducks fed with linseed oil. Meanwhile, dietary linseed oil changed liver fatty acid composition, which was reflected in the increase in the abundance of downstream metabolites, such as α-linolenic acid (ALA; 18:3n-3) as a substrate, including n-3 PUFA and its related glycerophospholipids, and a decrease in downstream n-6 PUFA synthesis using linoleic acid (LA; 18:2n-6) as a substrate. Moreover, the anabolism of PUFA in duck livers showed substrate-dependent effects, and the expression of related proteins in the process of fatty acid anabolism, such as FADS2, LPIN2, and PLA2G4A, were significantly regulated by linseed oil. Collectively, our work highlights the ALA substrate dependence during n-3 PUFA synthesis in duck livers. The present study expands our knowledge of the process products of PUFA metabolism and provides some potential biomarkers for liver health.

Regulation of Δ6Fads2 Gene Involved in LC-PUFA Biosynthesis Subjected to Fatty Acid in Large Yellow Croaker (Larimichthys crocea) and Rainbow Trout (Oncorhynchus mykiss).

Δ6 fatty acyl desaturase (Δ6Fads2) is regarded as the first rate-limiting desaturase that catalyzes the biosynthesis of long-chain polyunsaturated fatty acids (LC-PUFA) from 18-carbon fatty acid in vertebrates, but the underlying regulatory mechanism of fads2 has not been comprehensively understood. This study aimed to investigate the regulation role of fads2 subjected to fatty acid in large yellow croaker and rainbow trout. In vivo, large yellow croaker and rainbow trout were fed a fish oil (FO) diet, a soybean oil (SO) diet or a linseed oil (LO) diet for 10 weeks. The results show that LO and SO can significantly increase fads2 expression (p < 0.05). In vitro experiments were conducted in HEK293T cells or primary hepatocytes to determine the transcriptional regulation of fads2. The results show that CCAAT/enhancer-binding protein α (C/EBPα) can up-regulate fads2 expression. GATA binding protein 3 (GATA3) can up-regulate fads2 expression in rainbow trout but showed opposite effect in large yellow croaker. Furthermore, C/EBPα protein levels were significantly increased by LO and SO (p < 0.05), gata3 expression was increased in rainbow trout by LO but decreased in large yellow croaker by LO and SO. In conclusion, we revealed that FO replaced by LO and SO increased fads2 expression through a C/EBPα and GATA3 dependent mechanism in large yellow croaker and rainbow trout. This study might provide critical insights into the regulatory mechanisms of fads2 expression and LC-PUFA biosynthesis.

Inhibition of Δ-6 desaturase reduces fatty acid re-esterification in 3T3-L1 adipocytes independent of changes in n3-PUFA cellular content.

Δ-6 desaturase (D6D) is a key enzyme in the synthesis of long-chain polyunsaturated fatty acids (LC-PUFA). Evidence suggests that reduced D6D activity not only disrupts LC-PUFA production, but also impacts whole body lipid handling and body weight; however, the mechanisms remain largely unexplored. Therefore, we investigated the effect of D6D inhibition on the regulation of lipid accumulation in 3T3-L1 adipocytes with and without changes in n-3 PUFA content. 3T3-L1 cells were treated with a D6D inhibitor (SC-26196) in the presence or absence of α-linolenic acid (ALA) throughout differentiation. We found that D6D inhibition blocked the conversion of ALA to eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPAn-3) when ALA was supplemented, while no changes in n-3 PUFA content were observed in cells treated with the D6D inhibitor alone. D6D inhibited cells had reduced triacylglycerol (TAG) accumulation despite an EPA/DPA deficiency. In addition, analyses of cellular protein markers, as well as non-esterified fatty acids and glycerol release in medium, suggested an increase in lipolysis and a decrease in fatty acid re-esterification in D6D-inhibited cells, independent of n-3 PUFA changes. To provide further evidence, we treated cells with the D6D inhibitor in the presence or absence of EPA and compared them with ALA-treated cells. Although EPA further reduced TAG content, the reduced markers of fatty acid re-esterification were not affected by ALA or EPA. Collectively, this study provides new insight showing that D6D inhibition reduces TAG accumulation and fatty acid re-esterification in adipocytes independent of changes in n-3 PUFA cellular content.

The Partitioning of Newly Assimilated Linoleic and α-Linolenic Acids Between Synthesis of Longer-Chain Polyunsaturated Fatty Acids and Hydroxyoctadecaenoic Acids Is a Putative Branch Point in T-Cell Essential Fatty Acid Metabolism.

Longer-chain polyunsaturated fatty acids (LCPUFAs) ≥20 carbons long are required for leukocyte function. These can be obtained from the diet, but there is some evidence that leukocytes can convert essential fatty acids (EFAs) into LCPUFAs. We used stable isotope tracers to investigate LCPUFA biosynthesis and the effect of different EFA substrate ratios in human T lymphocytes. CD3+ T cells were incubated for up to 48 h with or without concanavalin A in media containing a 18:2n-6:18:3n-3 (EFA) ratio of either 5:1 or 8:1 and [13C]18:3n-3 plus [d5]18:2n-6. Mitogen stimulation increased the amounts of 16:1n-7, 18:1n-9, 18:2n-6, 20:3n-6, 20:4n-6, 18:3n-3, and 20:5n-3 in T cells. Expression of the activation marker CD69 preceded increased FADS2 and FADS1 mRNA expression and increased amounts of [d5]20:2n-6 and [13C]20:3n-3 at 48 h. In addition, 22-carbon n-6 or n-3 LCPUFA synthesis was not detected, consistent with the absence of ELOVL2 expression. An EFA ratio of 8:1 reduced 18:3n-3 conversion and enhanced 20:2n-6 synthesis compared to a 5:1 ratio. Here, [d5]9- and [d5]-13-hydroxyoctadecadienoic (HODE) and [13C]9- and [13C]13-hydroxyoctadecatrienoic acids (HOTrE) were the major labelled oxylipins in culture supernatants; labelled oxylipins ≥20 carbons were not detected. An EFA ratio of 8:1 suppressed 9- and 13-HOTrE synthesis, but there was no significant effect on 9- and 13-HODE synthesis. These findings suggest that partitioning of newly assimilated EFA between LCPUFA synthesis and hydroxyoctadecaenoic acid may be a metabolic branch point in T-cell EFA metabolism that has implications for understanding the effects of dietary fats on T lymphocyte function.

Influence of Dietary Lipids and Environmental Salinity on the n-3 Long-Chain Polyunsaturated Fatty Acids Biosynthesis Capacity of the Marine Teleost Solea senegalensis.

Fish vary in their ability to biosynthesise long-chain polyunsaturated fatty acids (LC-PUFA) depending upon the complement and function of key enzymes commonly known as fatty acyl desaturases and elongases. It has been reported in Solea senegalensis the existence of a Δ4 desaturase, enabling the biosynthesis of docosahexaenoic acid (DHA) from eicosapentaenoic acid (EPA), which can be modulated by the diet. The present study aims to evaluate the combined effects of the partial replacement of fish oil (FO) with vegetable oils and reduced environmental salinity in the fatty acid composition of relevant body compartments (muscle, hepatocytes and enterocytes), the enzymatic activity over α-linolenic acid (ALA) to form n-3 LC-PUFA through the incubation of isolated hepatocytes and enterocytes with [1-14C] 18:3 n-3, and the regulation of the S. senegalensis fads2 and elovl5 in the liver and intestine. The presence of radiolabelled products, including 18:4n-3, 20:4n-3 and EPA, provided compelling evidence that a complete pathway enabling the biosynthesis of EPA from ALA, establishing S. senegalensis, has at least one Fads2 with ∆6 activity. Dietary composition prevailed over salinity in regulating the expression of fads2, while salinity did so over dietary composition for elovl5. FO replacement enhanced the proportion of DHA in S. senegalensis muscle and the combination with 20 ppt salinity increased the amount of n-3 LC-PUFA in hepatocytes.

Dietary ω3-and ω6-Polyunsaturated fatty acids reconstitute fertility of Juvenile and adult Fads2-Deficient mice.

OBJECTIVE: Polyunsaturated fatty acids (PUFAs), including essential fatty acids linoleic and α-linolenic acid and derived long chain and very long chain ω3-and ω6-polyunsaturated fatty acids, are vital structures in mammalian membrane systems and signaling molecules, pivotal in brain development, lipid, and energy metabolism and in female and male fertility during human evolution. Numerous nutritional studies suggest imbalance of PUFA metabolism as a critical factor in the pathogenesis of several human lifestyle diseases: dyslipoproteinemia, obesity, cardiovascular and neurodegenerative diseases, and infertility. The lack of unbiased animal models impedes molecular interpretation of the role of synthesized and dietary supplied PUFAs in these conditions. In this study, we used a Δ6 fatty acid desaturase (FADS2) deficient mouse mutant lacking key enzyme activity in the biosynthesis of ω3-and ω6-PUFAs from EFAs to address the molecular role of PUFAs in female and male fertility. Infertility is a hallmark of the pleiotropic but auxotrophic fads2-/- phenotype and is therefore helpful for stringent dietary studies on the role of individual PUFAs. METHODS: Feeding regimens: Age- and gender-matched infertile fads2-/- mice were maintained on defined diets, normal diet containing essential fatty acids, and supplemented with ω6-arachidonic acid, ω3-docosahexaenoic acid, and arachidonic/docosahexaenoic acid, starting (a) after weaning and (b) initiated in 4-month-old female and male fads2-/- mice. Phospho- and sphingolipidomes of ovarian and testicular membrane lipid bilayers in each cohort were established and the impact on the expression and topology of membrane marker proteins, membrane morphology, germ cell development, and female and male fertility in the respective cohorts was elaborated. RESULTS: PUFA synthesis deficiency caused a halt to folliculogenesis, atresia of oocytes, and infertility of fads2-/- female mice. A PUFA-deficient membrane lipid bilayer core structure led to the disassembly of the gap junction network of the follicular granulosa cells. In fads2-/- testis, the blood-testis barrier was disrupted and spermatogenesis arrested, leading to infertility. Sustained supply of combined AA and DHA remodeled the PUFA-deficient ovarian and testicular membrane lipidomes, facilitating the reassembly of the functional gap junction network for regular ovarian cycles and the reconstitution of the blood-testis barrier in Sertoli cells, reconstituting fertility not only in developing newborns, but surprisingly also in adult infertile fads2-/- mice. CONCLUSIONS: These findings demonstrate the previously unrecognized membrane structure-based molecular link between nutrient ω3-and ω6-PUFAs, gonadal membrane structures, and female and male fertility and might foster studies of the pivotal role of dietary PUFAs in human fertility.

Duration of the flaxseed diet promotes deposition of n-3 fatty acids in the meat and skin of Peking ducks.

BACKGROUND: Polyunsaturated fatty acids (PUFA), particularly n-3, have beneficial effects on human health, and for this reason foodstuffs with increased content of n-3 PUFA are now very common and widely available. DESIGN: This study was conducted to investigate the effect of the duration of a flaxseed diet on Peking duck's growth performance, antioxidant status, gene expression, and fatty acid profile of the meat. A total of 792 12-day-old white Peking ducks were divided into four groups. In the control group, animals were provided with a basal diet. In the three experimental groups, animals were fed a 10% flax seed diet with vitamin E at 13, 23, and 33 days of age for 30, 20, and 10 days, respectively. RESULTS: The growth performance of the ducks decreased with flaxseed diet's duration. Both body weight and body weight gain decreased linearly while Feed conversion ratios (FCR) increased in the group of ducks fed flaxseed compared to control ducks. Serum triglycerides (TG), very low density lipoprotein (VLDL), low density lipoprotein cholesterol (LDL-C), and aspartate aminotransferase (AST) linearly decreased while high density lipoprotein cholesterol (HDL-C) and lipopolysaccharide (LPS) levels increased by feeding flaxseed up to 30 days. The expression of lipin-1 gene (LPIN-1) and fatty acid desaturase 2 (FADS2) linearly increased in ducks fed flaxseed for 30 days. Linolenic acid (n-3) and its long-chain metabolites like eicosatetraenoic acid (ETA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and total n-3 fatty acids (FA) linearly increased while the ratio of n-6 to n-3 was reduced with increased duration of flaxseed supplementation. CONCLUSION: Overall, we found that increasing the duration of flaxseed diet with vitamin E for more than 10 days had a mild adverse effect on duck's growth performance but enrichedits meat with long-chain PUFA and decreased the n-6 to n-3 ratio, providing quality meat for health-conscious consumers. A period of 20 days is good for producing n-3 enriched Peking duck meat and skin.

Early nutrition in combination with polymorphisms in fatty acid desaturase gene cluster modulate fatty acid composition of cheek cells' glycerophospholipids in school-age children.

Variants in the human genes of fatty acid (FA) desaturase 1 (FADS1), 2 (FADS2) and 3 (FADS3) are associated with PUFA blood levels. We explored if maternal prenatal supplementation and children's genetic variation in seventeen SNP of the FADS1, FADS2 and FADS3 gene cluster influence twenty-one of the most relevant cheek cells' derived FA in glycerophospholipids (GPL-FA). The study was conducted in 147 Spanish and German mother-children pairs participating in the Nutraceuticals for a Healthier Life (NUHEAL) study at 8, 9 and 9·5 years. Linear and mixed model longitudinal regression analyses were performed. Maternal fish-oil (FO) or FO+5-methyltetrahydrofolate (5-MTHF) supplementation during pregnancy was associated with a significant decrease of arachidonic acid (AA) concentrations in cheek cell GPL in the offspring, from 8 to 9·5 years; furthermore, maternal FO+5-MTHF supplementation was associated with higher n-6 docosapentaenoic acid concentrations in their children at age 8 years. FADS1 rs174556 polymorphism and different FADS2 genotypes were associated with higher concentrations of linoleic and α-linolenic acids in children; moreover, some FADS2 genotypes determined lower AA concentrations in children's cheek cells. It is suggested an interaction between type of prenatal supplementation and the offspring genetic background driving GPL-FA levels at school age. Prenatal FO supplementation, and/or with 5-MTHF, seems to stimulate n-3 and n-6 FA desaturation in the offspring, increasing long-chain PUFA concentrations at school age, but depending on children's FADS1 and FADS2 genotypes. These findings suggest potential early nutrition programming of FA metabolic pathways, but interacting with children's FADS polymorphisms.

Tropical Vegetable Oils Do Not Alter Growth Performance in African Catfish through a High n-6 Polyunsaturated Fatty Acids Biosynthesis Capacity.

The main objective of this study was to determine the best vegetable oils (VO) for nutrition of African catfish by assessing the effects of a complete replacement of fish oil (FO) by different VO sources on its growth performance, fatty acid composition, and elongase-desaturase gene expression levels. Fish (16.2 g of initial body weight) were fed with five experimental isonitrogenous, isolipidic, and isoenergetic diets in which FO was totally replaced by cottonseed oil (CO), palm oil (PO), desert date oil (DO), or Shea butter (SB). Complete replacement of FO with VO did not affect growth performance except for low values in fish fed SB diet. Muscle n-3 LC-polyunsaturated fatty acids (PUFA) were significantly reduced in fish fed VO-based diets when compared with FO fed fish. However, the muscle arachidinic acid (ARA) levels in phospholipid class were 1.4 to 1.6 times higher in fish fed CO and DO diets than FO fed fish despite the lower ARA suppliers from these VO-based diets, suggesting endogenous LC-PUFA biosynthesis from PUFA precursors in fish fed these VO. The fads2 and elovl5 gene expression levels in liver of fish fed DO were also higher compared to FO controls. Therefore, all the results support the hypothesis that African catfish has higher biosynthesis capacity to convert vegetable n-6 PUFA precursors like linoleic acid (LNA, 18:2n-6) into n-6 LC-PUFA of the ARA type, compared to the conversion of vegetable α-linolenic acid (ALA, 18:3n-3) into n-3 LC-PUFA of the eicosapentanoic acid (EPA) or docosahexanoic acid (DHA) type. The results also indicate that DO can be recommended as the best alternative to FO replacement in African catfish nutrition.

Comparing the serum TAG response to high-dose supplementation of either DHA or EPA among individuals with increased cardiovascular risk: the ComparED study.

Studies have shown that the reduction in serum TAG concentrations with long-chain n-3 fatty acid supplementation is highly variable among individuals. The objectives of the present study were to compare the proportions of individuals whose TAG concentrations lowered after high-dose DHA and EPA, and to identify the predictors of response to both modalities. In a double-blind, controlled, crossover study, 154 men and women were randomised to three supplemented phases of 10 weeks each: (1) 2·7 g/d of DHA, (2) 2·7 g/d of EPA and (3) 3 g/d of maize oil, separated by 9-week washouts. As secondary analyses, the mean intra-individual variation in TAG was calculated using the standard deviation from the mean of four off-treatment samples. The response remained within the intra-individual variation (±0·25 mmol/l) in 47 and 57 % of participants after DHA and EPA, respectively. Although there was a greater proportion of participants with a reduction >0·25 mmol/l after DHA than after EPA (45 υ. 32 %; P 0·25 mmol/l after both DHA and EPA had higher non-HDL-cholesterol, TAG and insulin concentrations compared with other responders at baseline (all P < 0·05). In conclusion, supplementation with 2·7 g/d DHA or EPA had no meaningful effect on TAG concentrations in a large proportion of individuals with normal mean TAG concentrations at baseline. Although DHA lowered TAG in a greater proportion of individuals compared with EPA, the magnitude of TAG lowering among them was similar.

Dietary fish oil and flaxseed for rabbit does: fatty acids distribution and Δ6-desaturase enzyme expression of different tissues.

Standard feeds are imbalanced in term of n-6/n-3 polyunsaturated fatty acids (PUFA) ratio, with a low proportion of the latter. The reproductive system appears to be strongly affected by administration of n-3 PUFA, and ingredients rich in α-linolenic acid (ALA; i.e. vegetable sources) or EPA and DHA acids (i.e. fish oil) can be included in animal diets to balance PUFA intake. The aim of this study was to evaluate the effect of dietary supplementation with flaxseed (ALA) or fish oil (EPA and DHA) on PUFA metabolism in rabbit does. A total of 60 New Zealand White female rabbits were assigned to three experimental groups: control group, FLAX group fed 10% extruded flaxseed and FISH group fed 3% fish oil. Blood, milk, liver and ovaries were collected from the does to assess the lipid composition; furthermore, FADS2 gene expression was assessed in liver and ovary tissues. Reproductive performance of does was also recorded. The fertility rate and number of weaned rabbits improved with n-3 dietary supplementation: does at first parity showed the lowest reproductive results, but the administration of n-3 reduced the gap between primiparous and multiparous does. Feed consumption and milk production were not affected by the feeding regime. The fatty acid composition of milk, plasma, liver and ovaries were widely influenced by diet, showing higher concentrations of n-3 long-chain PUFA (LCP) in does fed with n-3 enriched diets. FISH diet resulted in the highest n-3 LCP enrichment, whereas in the FLAX group, this increase was lower. Blood and milk showed low levels of LCP, whereas liver and ovaries were the main sites of n-3 LCP synthesis and accumulation. Accordingly, although the liver is the main metabolic centre for LCP synthesis, ovaries also have a prominent role in LCP generation. FADS2 expression in liver and ovary tissue was downregulated by FISH administration. In conclusion, the enrichment of diets with n-3 PUFA could be an effective strategy for improving the reproductive performance of does.

Docosahexaenoic Acid (DHA) Inhibits FADS2 Expression in Astrocytes but Increases Survival of Neurons Co-cultured with DHA-enriched Astrocytes.

Docosahexaenoic acid (DHA), the most abundant n-3 polyunsaturated fatty acid (n-3PUFA) in the brain, has attracted great importance for a variety of neuronal functions such as signal transduction through plasma membranes, neuronal plasticity, and neuroprotection. Astrocytes that provide structural, functional, and metabolic support for neurons, express ∆6- desaturase encoded by FADS2 gene that can be, next to the plasma DHA pool, additional source of DHA in the brain. Furthermore, the genetic variations of FADS gene cluster has been found in children with developmental disorders, and are associated with cognitive functions. Since, the regulation of DHA biosynthesis in astrocytes remains poorly studied the aim of this study was to determine the effect of palmitic acid (PA), α-linolenic acid (ALA) or docosahexaenoic acid (DHA), on the transcription of FADS2 gene in astrocytes and survival of neurons challenged with oxidative compounds after co-culture with astrocytes exposed to DHA. The lipid profile in cell membranes after incubation with fatty acids was determined by gas chromatography, and FADS2 expression was analyzed using real-time PCR. The viability of neurons cocultured with PUFA-enriched astrocytes was investigated by flow cytometry after staining cells with annexin V-FITC and PI. The results showed that DHA suppressed (P <0.01), PA stimulated (P <0.01), while ALA did not change the FADS2 gene expression after 24 h incubation of astrocytes with fatty acids. Although FADS2 mRNA was down-regulated by DHA, its level in astrocytic membranes significantly increased (P <0.01). Astrocytes with DHA-enriched membrane phospholipids markedly enhanced neuronal resistance to cytotoxic compounds and neuronal survival. These results suggest that beneficial effects of supplementation with n-3 PUFA in Alzheimer disease and in psychiatric disorders is caused, in part, by increased efficacy of DHA-enriched astrocytes to protect neurons under adverse conditions in the brain.

The compositional and metabolic responses of gilthead seabream (Sparus aurata) to a gradient of dietary fish oil and associated n-3 long-chain PUFA content.

The replacement of fish oil (FO) with vegetable oil (VO) in feed formulations reduces the availability of n-3 long-chain PUFA (LC-PUFA) to marine fish such as gilthead seabream. The aim of this study was to examine compositional and physiological responses to a dietary gradient of n-3 LC-PUFA. Six iso-energetic and iso-nitrogenous diets (D1-D6) were fed to seabream, with the added oil being a blend of FO and VO to achieve a dietary gradient of n-3 LC-PUFA. Fish were sampled after 4 months feeding, to determine biochemical composition, tissue fatty acid concentrations and lipid metabolic gene expression. The results indicated a disturbance to lipid metabolism, with fat in the liver increased and fat deposits in the viscera reduced. Tissue fatty acid profiles were altered towards the fatty acid compositions of the diets. There was evidence of endogenous modification of dietary PUFA in the liver which correlated with the expression of fatty acid desaturase 2 (fads2). Expression of sterol regulatory element binding protein 1 (srebp1), fads2 and fatty acid synthase increased in the liver, whereas PPARα1 pathways appeared to be supressed by dietary VO in a concentration-dependent manner. The effects in lipogenic genes appear to become measurable in D1-D3, which agrees with the weight gain data suggesting that disturbances to energy metabolism and lipogenesis may be related to performance differences. These findings suggested that suppression of ß-oxidation and stimulation of srebp1-mediated lipogenesis may play a role in contributing toward steatosis in fish fed n-3 LC-PUFA deficient diets.

Parental nutritional programming and a reminder during juvenile stage affect growth, lipid metabolism and utilisation in later developmental stages of a marine teleost, the gilthead sea bream (Sparus aurata).

Nutrition during periconception and early development can modulate metabolic routes to prepare the offspring for adverse conditions through a process known as nutritional programming. In gilthead sea bream, replacement of fish oil (FO) with linseed oil (LO) in broodstock diets improves growth in the 4-month-old offspring challenged with low-FO and low-fishmeal (FM) diets for 1 month. The present study further investigated the effects of broodstock feeding on the same offspring when they were 16 months old and were challenged for a second time with the low-FM and low-FO diet for 2 months. The results showed that replacement of parental moderate-FO feeding with LO, combined with juvenile feeding at 4 months old with low-FM and low-FO diets, significantly (P<0·05) improved offspring growth and feed utilisation of low-FM/FO diets even when they were 16 months old: that is, when they were on the verge of their first reproductive season. Liver fatty acid composition was significantly affected by broodstock or reminder diets as well as by their interaction. Moreover, the reduction of long-chain PUFA and increase in α-linolenic acid and linoleic acid in broodstock diets lead to a significant down-regulation of hepatic lipoprotein lipase (P<0·001) and elongation of very long-chain fatty acids protein 6 (P<0·01). Besides, fatty acid desaturase 2 values were positively correlated to hepatic levels of 18 : 4n-3, 18 : 3n-6, 20 : 5n-3, 22 : 6n-3 and 22 : 5n-6. Thus, this study demonstrated the long-term nutritional programming of gilthead sea bream through broodstock feeding, the effect of feeding a 'reminder' diet during juvenile stages to improve utilisation of low-FM/FO diets and fish growth as well as the regulation of gene expression along the fish's life-cycle.

Effect of α-linolenic acid and DHA intake on lipogenesis and gene expression involved in fatty acid metabolism in growing-finishing pigs.

The regulation of lipogenesis mechanisms related to consumption of n-3 PUFA is poorly understood. The aim of the present study was to find out whether α-linolenic acid (ALA) or DHA uptake can have an effect on activities and gene expressions of enzymes involved in lipid metabolism in the liver, subcutaneous adipose tissue and longissimus dorsi (LD) muscle of growing-finishing pigs. Six groups of ten pigs received one of six experimental diets supplemented with rapeseed oil in the control diet, extruded linseed, microalgae or a mixture of both to implement different levels of ALA and DHA with the same content in total n-3. Results were analysed for linear and quadratic effects of DHA intake. The results showed that activities of malic enzyme (ME) and fatty acid synthase (FAS) decreased linearly in the liver with dietary DHA. Although the expression of the genes of these enzymes and their activities were poorly correlated, ME and FAS expressions also decreased linearly with DHA intake. The intake of DHA down-regulates the expressions of other genes involved in fatty acid (FA) metabolism in some tissues of pigs, such as fatty acid desaturase 2 and sterol-regulatory element binding transcription factor 1 in the liver and 2,4-dienoyl CoA reductase 2 in the LD muscle. FA oxidation in the LD muscle and FA synthesis decreased in the liver with increasing amount of dietary DHA, whereas a retroconversion of DHA into EPA seems to be set up in this last tissue.

Dietary Linseed Oil Reduces Growth While Differentially Impacting LC-PUFA Synthesis and Accretion into Tissues in Eurasian Perch (Perca fluviatilis).

The aim of this study was to evaluate the impact of replacing dietary fish oil (FO) with linseed oil (LO) on growth, fatty acid composition and regulation of lipid metabolism in Eurasian perch (Perca fluviatilis) juveniles. Fish (17.5 g initial body weight) were fed isoproteic and isoenergetic diets containing 116 g/kg of lipid for 10 weeks. Fish fed the LO diet displayed lower growth rates and lower levels of DHA in the liver and muscle than fish fed the FO diet, while mortality was not affected by dietary treatment. However, DHA content recorded in the liver and muscle of fish fed the LO diet remained relatively high, despite a weight gain of 134 % and a reduced dietary level of long-chain polyunsaturated fatty acids (LC-PUFA), suggesting endogenous LC-PUFA biosynthesis. This was supported by the higher amounts of pathway intermediates, including 18:4n-3, 20:3n-3, 20:4n-3, 18:3n-6 and 20:3n-6, recorded in the liver of fish fed the LO diet in comparison with those fed the FO diet. However, fads2 and elovl5 gene expression and FADS2 enzyme activity were comparable between the two groups. Similarly, the expression of genes involved in eicosanoid synthesis was not modulated by dietary LO. Thus, the present study demonstrated that in fish fed LO for 10 weeks, growth was reduced but DHA levels in tissues were largely maintained compared to fish fed FO, suggesting a physiologically relevant rate of endogenous LC-PUFA biosynthesis capacity.

Alteration of delta-6-desaturase (FADS2), secretory phospholipase-A2 (sPLA2) enzymes by Hot-nature diet with co-supplemented hemp seed, evening primrose oils intervention in multiple sclerosis patients.

BACKGROUND: The effect of nutrition and dietary supplements as environmental factors has been suggested as possible factors affecting both disease risk and progression in on the course of multiple sclerosis with complex genetic-risk profiles. This study was aimed to assess regulation of surface-membrane enzymes such as Delta-6-desaturase (FADS2), secretory Phospholipase A2(sPLA2) by hemp seed and evening primrose oils as well as Hot-natured dietary intervention in relapsing remitting multiple sclerosis (RRMS) patients. METHODS AND MATERIALS: In this double blind, randomized trial, 100 RRMS patients with Extended disability status score (EDSS)<6 were allocated into 3 groups: "Group A" who received co-supplemented hemp seed and evening primrose oils along with advised Hot nature diet; "Group B", who received olive oil; "Group C", who received the co-supplemented oils. Clinically EDSS and functional score as well as biochemical parameters [blood cells polyunsaturated fatty acid (PUFA), FADS2, sPLA2] were assessed at baseline and after 6 months. RESULTS: Mean follow-up was 180±2.9SD days (N=65, 23 M and 42 F aged 34.25±8.07 years with disease duration 6.80±4.33 years). There was no significant difference in studies parameters at baseline. After 6 months, significant improvements in EDSS and functional score were found in the groups A and C while EDSS and pyramidal score showed significant increase in group B. Alteration of biochemical parameters showed improvement in groups A and C whereas there was worsening condition for group B after the intervention. CONCLUSION: The co-supplemented hemp seed and evening primrose oils with Hot nature diet can have beneficial effects in improving clinical symptoms and signs in RRMS patients which were confirmed by regulation of surface-membrane enzymes.