Long-chain Polyunsaturated Ω3 Fatty Acids Research Articles

Dissection of the synthesis of polyunsaturated fatty acids in nematodes and Collembola of the soil fauna

It is becoming increasingly clear that not only unicellular, photoautotrophic eukaryotes, plants, and fungi, but also invertebrates are capable of synthesizing ω3 long-chain polyunsaturated fatty acids (LC-PUFA) de novo. However, the distribution of this anabolic capacity among different invertebrate groups and its implementation at the gene and protein level are often still unknown. This study investigated the PUFA pathways in common soil fauna, i.e. two nematode and two Collembola species. Of these, one species each (Panagrellus redivivus, Folsomia candida) was assumed to produce ω3 LC-PUFA de novo, while the others (Acrobeloides bodenheimeri, Isotoma caerulea) were supposed to be unable to do so. A highly labeled oleic acid (99 % 13C) was supplemented and the isotopic signal was used to trace its metabolic path. All species followed the main pathway of lipid biosynthesis. However, in A. bodenheimeri this terminated at arachidonic acid (ω6 PUFA), whereas the other three species continued the pathway to eicosapentaenoic acid (ω3 PUFA), including I. caerulea. For the nematode P. redivivus the identification and functional characterization of four new fatty acid desaturase (FAD) genes was performed. These genes encode the FAD activities Δ9, Δ6, and Δ5, respectively. Additionally, the Δ12 desaturase was analyzed, yet the observed activity of an ω3 FAD could not be attributed to a coding gene. In the Collembola F. candida, 11 potential first desaturases (Δ9) and 13 front-end desaturases (Δ6 or Δ5 FADs) have been found. Further sequence analysis indicates the presence of omega FADs, specifically Δ12, which are likely derived from Δ9 FADs.

Omega-3 fatty acids decrease CRYAB, production of oncogenic prostaglandin E2 and suppress tumor growth in medulloblastoma

AimsMedulloblastoma (MB) is one of the most common malignant central nervous system tumors of childhood. Despite intensive treatments that often leads to severe neurological sequelae, the risk for resistant relapses remains significant. In this study we have evaluated the effects of the ω3-long chain polyunsaturated fatty acids (ω3-LCPUFA) docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on MB cell lines and in a MB xenograft model. Main methodsEffects of ω3-LCPUFA treatment of MB cells were assessed using the following: WST-1 assay, cell death probes, clonogenic assay, ELISA and western blot. MB cells were implanted into nude mice and the mice were randomized to DHA, or a combination of DHA and EPA treatment, or to control group. Treatment effects in tumor tissues were evaluated with: LC-MS/MS, RNA-sequencing and immunohistochemistry, and tumors, erythrocytes and brain tissues were analyzed with gas chromatography. Key findingsω3-LCPUFA decreased prostaglandin E2 (PGE2) secretion from MB cells, and impaired MB cell viability and colony forming ability and increased apoptosis in a dose-dependent manner. DHA reduced tumor growth in vivo, and both PGE2 and prostacyclin were significantly decreased in tumor tissue from treated mice compared to control animals. All ω3-LCPUFA and dihomo-γ-linolenic acid increased in tumors from treated mice. RNA-sequencing revealed 10 downregulated genes in common among ω3-LCPUFA treated tumors. CRYAB was the most significantly altered gene and the downregulation was confirmed by immunohistochemistry. SignificanceOur findings suggest that addition of DHA and EPA to the standard MB treatment regimen might be a novel approach to target inflammation in the tumor microenvironment.

28-Day oral (gavage) and 13-week (dietary) toxicity studies of DHA canola oil and DHA canola meal in rats

Omega-3 (ω3) fatty acids are a family of polyunsaturated fats. Two of the ω3 long-chain polyunsaturated fatty acids (LC-PUFA), eicosapentaenoic acid (EPA, ω3, 20:5Δ5,8,11,14,17) and docosahexaenoic acid (DHA, ω3, 22:6Δ4,7,10,13,16,19) are sourced primarily from fish. Higher consumption, limited fishing quotas and other environmental factors (e.g., heavy metals) have warranted a need for alternative sources. Nuseed offers a genetically engineered canola (Brassica napus) event,1 DHA canola (OECD Unique Identifier NS-B5ØØ27-4), which has been modified to introduce a pathway for production of the ω3 LC-PUFAs DHA and EPA from oleic acid (OA) in the seed oil. To accomplish this, genes were sourced from marine microalgae and common yeast then incorporated into canola to produce DHA canola, one of the first land-based production systems for ω 3 PUFAs. Safety was evaluated in part by conducting a repeated dose 28-day toxicity study and a dietary 13-week toxicity study using CD® IGS [Crl:CD(SD)] rats. In the 28-day study, conventional and DHA canola oil were administered orally (via gavage); no treatment-related adverse effects were observed. The 13-week toxicity study was subsequently conducted where DHA canola oil and meal were administered by dietary admixture. No adverse effects were noted in clinical observations, clinical pathology, or histopathology. These studies support the food and feed safety of DHA canola oil and meal.

Yogurt Enriched with Isochrysis galbana: An Innovative Functional Food.

Microalgae are a valuable and innovative emerging source of natural nutrients and bioactive compounds that can be used as functional ingredients in order to increase the nutritional value of foods to improve human health and to prevent disease. The marine microalga Isochrysis galbana has great potential for the food industry as a functional ingredient, given its richness in ω3 long chain-polyunsaturated fatty acids (LC-PUFAs), with high contents of oleic, linoleic, alpha-linolenic acid (ALA), stearidonic, and docosahexaenoic (DHA) acids. This study focuses on the formulation of a functional food by the incorporation of 2% (w/w) of I. galbana freeze-dried biomass and 2% (w/w) of I. galbana ethyl acetate lipidic extract in solid natural yogurts preparation. In the functional yogurt enriched with microalgal biomass, the ω3 LC-PUFA’s content increased (to 60 mg/100 g w/w), specifically the DHA content (9.6 mg/100 g ww), and the ω3/ω6 ratio (augmented to 0.8). The in vitro digestion study showed a poor bioaccessibility of essential ω3 LC-PUFAs, wherein linoleic acid (18:2 ω6) presented a bioaccessibility inferior to 10% and no DHA or eicosapentaenoic acid (EPA) was detected in the bioaccessible fraction of the functional yogurts, thus indicating a low accessibility of lipids during digestion. Notwithstanding, when compared to the original yogurt, an added value novel functional yogurt with DHA and a higher ω3 LC-PUFAs content was obtained. The functional yogurt enriched with I. galbana can be considered important from a nutritional point of view and a suitable source of essential FAs in the human diet. However, this needs further confirmation, entailing additional investigation into bioavailability through in vivo assays.

Concentrates of buttermilk and krill oil improve cognition in aged rats

Cognitive decline is one of the hallmarks of aging and can vary from mild cognitive impairment to dementia to Alzheimer's disease. In addition to some lifestyle interventions, there is room for the use of nutraceuticals/functional foods as pharma-nutritional tools to lessen the burden of cognitive decline before it worsens. We previously reported the promising molecular actions of milk fat globule membranes and krill oil concentrates in a rat model of aging. In this study, we concentrated on the activities on cognition, using an array of validated tests. We also performed lipidomic analyses of plasma, erythrocytes, and different brain areas. We report lower emotional memory (contextual fear conditioning) in aged rats supplemented with concentrates of polar lipids from buttermilk or krill oil at doses that approximate human consumption. No other behavioral parameter was significantly influenced by the supplements, calling for further research to confirm or not the purported salubrious activities of polar lipids, namely those rich in ω3 long-chain polyunsaturated fatty acids, on cognitive decline.

Reviews and syntheses: Insights into deep-sea food webs and global environmental gradients revealed by stable isotope (<i>δ</i><sup>15</sup>N, <i>δ</i><sup>13</sup>C) and fatty acid trophic biomarkers

Abstract. Biochemical markers developed initially for food-web studies of terrestrial and shallow-water environments have only recently been applied to deep-sea ecosystems (i.e., in the early 2000s). For the first time since their implementation, this review took a close look at the existing literature in the field of deep-sea trophic ecology to synthesize current knowledge. Furthermore, it provided an opportunity for a preliminary analysis of global geographic (i.e., latitudinal, along a depth gradient) trends in the isotopic (δ15N, δ13C) and fatty acid composition of deep-sea macro- and megafauna from heterotrophic systems. Results revealed significant relationships along the latitudinal and bathymetric gradients. Deep-sea animals sampled at temperate and polar latitudes displayed lower isotopic ratios and greater proportions of essential ω3 long-chain polyunsaturated fatty acids (LC-PUFAs) than did tropical counterparts. Furthermore, δ15N and δ13C ratios as well as proportions of arachidonic acid increased with increasing depth. Since similar latitudinal trends in the isotopic and fatty acid composition were found in surface water phytoplankton and particulate organic matter, these results highlight the link across latitudes between surface primary production and deep-water communities. Because global climate change may affect quantity and quality (e.g., levels of essential ω3 PUFAs) of surface primary productivity, and by extension those of its downward flux, the dietary intake of deep-sea organisms may likely be altered. In addition, because essential ω3 PUFAs play a major role in the response to temperature variations, climate change may interfere with the ability of deep-sea species to cope with potential temperature shifts. Importantly, methodological disparities were highlighted that prevented in-depth analyses, indicating that further studies should be conducted using standardized methods in order to generate more reliable global predictions.

Presence or absence? Primary structure, regioselectivity and evolution of Δ12/ω3 fatty acid desaturases in nematodes

For vertebrates, the adequate supply of polyunsaturated fatty acids (PUFA) by the diet, in particular ω3 long-chain PUFA, is considered essential for neural development, growth and reproduction. In contrast to aquatic ecosystems, ω3 long-chain PUFA apparently are not widely available in the terrestrial food chain. Their de novo synthesis requires the presence of Δ12 and ω3 fatty acid desaturase enzymes, which are absent in vertebrates but present, for example, in the nematode Caenorhabditis elegans (FAT-2 and FAT-1). This raises the question if soil-dwelling nematodes offer substantial supply of these valuable nutritional compounds in terrestrial food webs. BLAST searches in available nematode genomes revealed the existence of fat-2 like genes in almost all clade III–V species, but failed to identify orthologs in clade I–II nematodes. An additional RT-PCR screen across soil-dwelling nematode species identified six novel fat-2 like genes. Hints for the genetic basis of a ω3 (fat-1) desaturase activity was found only in selected clade IV–V species, but not in clades I to III nematodes. Fatty acid pattern analyses following a PUFA-free cultivation and enzymatic characterization of six selected fat-2 or fat-1 like desaturases in yeast confirmed the findings from the genetic approaches. Thus, in similar soil habitats, taxa exist that can synthesize ω3 long-chain PUFA (as Panagrolaimus, Mesorhabditis and Caenorhabditis) whereas others are unable to do so (Acrobeloides, Cephalobus and Oscheius). While these nematodes do not differ in trophic position or major diet, distinction in reproduction mode may have led to the observed variations in desaturase genes.

Characterization of the fatty acyl elongase (elovl) gene family, and hepatic elovl and delta-6 fatty acyl desaturase transcript expression and fatty acid responses to diets containing camelina oil in Atlantic cod (Gadus morhua)

For aquaculture to become sustainable, there is a need to substitute fish oil [FO, rich in ω3 long chain polyunsaturated fatty acids (LC-PUFA) such as 20:5ω3 (EPA) and 22:6ω3 (DHA)] in aquafeed with plant oils such as camelina oil [CO, rich in C18 PUFA such as 18:3ω3 (ALA) and 18:2ω6 (LNA)]. The LC-PUFA are essential components in fish diets for maintaining optimal health, physiology and growth. However, most marine fish including Atlantic cod are inefficient at producing LC-PUFA from shorter chain precursors. Since elovl genes encode enzymes that play key roles in fatty acid biosynthesis, we hypothesized that they may be involved in Atlantic cod responses to diets rich in 18:3ω3 and 18:2ω6. Ten members of the cod elovl gene family were characterized at the mRNA level. RT-PCR was used to study constitutive expression of elovl transcripts in fifteen tissues. Some transcripts (e.g. elovl5) were ubiquitously expressed, while others had tissue-specific expression (e.g. elovl4a in brain and eye). Cod fed a CO-containing diet (100% CO replacement of FO and including solvent-extracted fish meal) had significantly lower weight gain, with significant up-regulation of elovl5 and fadsd6 transcripts in the liver as shown by QPCR analysis, compared with cod on a FO control diet after a 13-week trial. Multivariate statistical analyses (SIMPER and PCA) indicated that high 18:3ω3 and/or low ω3 LC-PUFA levels in the liver were associated with the up-regulation of elovl5 and fadsd6, which are involved in LC-PUFA biosynthesis in cod.

Spatial variation in fatty acid trophic markers in albacore tuna from the southwestern Pacific Ocean—A potential ‘tropicalization’ signal

Signature fatty acids were used to explore trophic variations in albacore and skipjack tuna sampled from the southwestern Pacific Ocean. There were clear spatial differences in fatty acid profiles between albacore sampled in the Coral (tropical zone centered at ~20°S) and Tasman (temperate zone centered at ~42°S) Seas; however, few differences were observed in fatty acid profiles of albacore sampled off Tasmania and New Zealand. Fatty acid signatures of the Tasman Sea samples reflected a food web based more on diatoms and included: 20:5ω3 (EPA), 18:1ω7, 22:1ω11, 18:2ω6, 18:4ω3, 18:3ω3, and 20:4ω3. In contrast, albacore from the Coral Sea had a distinct fatty acid signature which included 20:4ω6, 22:5ω6, 17:0, 22:4ω6, 24:0, and 17:1. Multivariate analyses revealed the importance of 22:6ω3 (DHA) in Coral Sea-caught albacore which also had a DHA/EPA ratio more than twice that in all other groups suggesting a greater dinoflagellate contribution and/or a higher trophic position. Fatty acid markers indicative of krill consumption were significantly higher in temperate-caught albacore although skipjack were closest in fatty acid composition to krill. These results were likely due to differences at the base of the food web in these two seas suggesting that signature fatty acids can be used as indicators of ecosystem change: in this case the gradual ‘tropicalization’ of the eastern seaboard of Australia through the southward extension of the East Australian Current. Our findings also indicate comparatively lower concentrations of healthful ω3 long-chain polyunsaturated fatty acids, in particular the content of DHA and EPA, in the tropical samples. This suggests that tropicalization could adversely affect the dietary intake of albacore and other marine predators in the region. Such changes are readily detectable by fatty acid analysis.

The metabolic syndrome of fructose-fed rats: Effects of long-chain polyunsaturated ω3 and ω6 fatty acids. VI. Further post-mortem investigations

The present study documents the increases in systolic arterial blood pressure, plasma leptin concentration and kidney proliferating cell nuclear antigen index, as well as the decreases in glutathione reductase, superoxide dismutase and catalase enzymatic activities in the liver, heart, kidney, soleus muscle and visceral adipose tissue homogenates of female rats exposed for 8 weeks to a diet containing 64% (w/w) D-fructose instead of 64% starch. In the fructose-fed rats, the partial substitution of sunflower oil by either safflower oil or salmon oil often opposed the fructose-induced changes in these variables. The present results, thus, extend to these functional, hormonal and enzymatic parameters the knowledge that the dietary supply of long-chain polyunsaturated ω6 fatty acids, mainly C18:2ω6, and long-chain polyunsaturated ω3 fatty acids opposes the undesirable features of the fructose-induced metabolic syndrome, with salmon oil demonstrating particular efficacy.

The metabolic syndrome of fructose-fed rats: Effects of long-chain polyunsaturated ω3 and ω6 fatty acids. III. Secretory behaviour of isolated pancreatic islets

In the present study, rats were exposed from the 8th week after birth and for the ensuing 8 weeks to diets containing either starch or fructose (64% w/w) and sunflower oil (5%). Two further groups of rats were exposed to the fructose-containing diet with substitution of part (1.6%) of the sunflower diet by an equal amount of either salmon oil rich in long-chain polyunsaturated ω3 fatty acids or safflower oil reach in long-chain polyunsaturated ω6 fatty acids. The insulin content of the islets and their secretory response to D-glucose (5.6, 8.3 and 16.7 mM), to the combination of D-glucose (5.6 mM) and D-fructose (10.0 mM) and to 2-ketoisocaproate (10.0 mM) were then measured. In the sunflower oil-fed rats, the dietary substitution of starch by fructose decreased basal insulin output, lowered the apparent Km for the insulinotropic action of D-glucose and altered the insulinotropic efficiency of the latter hexose relative to that of other nutrients. Some of these secretory perturbations were opposed by the enrichment of the diet in long-chain polyunsaturated fatty acids, especially ω3 fatty acids. It is proposed that these changes in B-cell secretory behaviour may be linked, in part at least, to both the apparent caloric efficiency of each diet, and hence to the regulation of the islet content in endogenous nutrients, and to alteration of insulin sensitivity considered as a major feature of the present animal model of metabolic syndrome.

The metabolic syndrome of fructose-fed rats: Effects of long-chain polyunsaturated ω3 and ω6 fatty acids. II. Time course of changes in food intake, body weight, plasma glucose and insulin concentrations and insulin resistance

The time course for changes in food intake, body weight, plasma glucose and insulin concentrations and HOMA index was monitored over a period of 8 weeks in rats exposed from the 8th week after birth to diets containing either starch or fructose and sunflower oil. In two further groups of rats exposed to the fructose-rich diet part of the sunflower oil was substituted by either salmon oil rich in long-chain polyunsaturated ω3 fatty acids or safflower oil rich in long-chain polyunsaturated ω6 fatty acids. Despite lower food intake, the gain in body weight was higher in fructose-fed rats than in starch-fed rats. The supplementation of the fructose-rich diet by either ω3 or ω6 fatty acids lowered both food intake and body weight gain. The measurements of plasma glucose and insulin concentrations, HOMA index and insulinogenic index performed after overnight starvation were in fair agreement with those recorded at the occasion of an intraperitoneal glucose tolerance test, with higher values for plasma glucose concentration and HOMA index in the fructose-fed rats exposed to the sunflower oil (with or without enrichment with ω6 fatty acids) than in the starch-fed rats exposed to the sunflower oil or fructose-fed rats exposed to a diet enriched with ω3 fatty acids. Such was also the case for the measurements of glycated albumin at sacrifice. Moreover, the insulinogenic index was lower in the fructose-fed rats with or without dietary enrichment in ω6 fatty acids than in the fructose-fed rats with dietary enrichment in ω3 fatty acids. The elucidation of the biochemical determinants of the later difference requires further investigations in isolated pancreatic islets.

The metabolic syndrome of fructose-fed rats: Effects of long-chain polyunsaturated ω3 and ω6 fatty acids. I. Intraperitoneal glucose tolerance test

The present series of experiments aim mainly at investigating the possible influence of changes in the com-position of dietary lipids (sunflower oil, salmon oil, safflower oil) upon the metabolic syndrome found in rats exposed to a fructose-rich diet. For purpose of comparison, a control group of rats received the sunflower oil diet with substitution of fructose by starch. An intraperitoneal glucose tolerance test, performed after overnight starvation fifty days after the start of the experiments at the 6th week after birth, indicated, as expected, impaired tolerance to glucose and deterioration of insulin sensitivity (HOMA index), without changes in the insulinogenic index, when comparing the fructose-fed rats to the starch-fed rats both exposed to the sunflower oil diet. In the fructose-fed rats, enrichment of the diet by long-chain polyunsaturated ω3 fatty acids supplied by salmon oil, a modest improvement of insulin sensitivity was opposed, in term of glucose homeostasis, by a decreased secretory response to glucose of insulin-producing cells. Last, in the fructose-fed rats, the partial substitution of sunflower oil by safflower oil rich in long-chain polyunsaturated ω6 fatty acids further deteriorated glucose homeostasis, with a higher mean HOMA index and a severe decrease of the insulinogenic index. These findings justify further investigations on such items as the time course for changes in metabolic and hormonal variables and both the metabolic and secretory responses of isolated pancreatic islets to selected nutrient secretagogues.

Plasma phospholipid-mediated transfer of docosahexaenoic acid from liver to brain phospholipids in type 1 and type 2 diabetic rats

Docosahexaenoic acid (C22:6ω3) generated in the liver from circulating α-linolenic acid (C18:3ω3) was recently proposed as the source of brain C22:6ω3 when the latter fatty acid is absent from the diet. The present study aims at exploring whether a comparable situation prevails in Types 1 and 2 diabetic rats, even when exposed to a normal diet. The fatty acid profile of liver, plasma and brain phospholipids (PL) was examined in 22 rats including 6 streptozotocin-induced diabetic animals (Type 1 diabetes), 8 Goto-Kakizaki rats (Type 2 diabetes) and 8 control animals. Both fed and overnight starved rats of both genders were included in this study. To avoid the interference of any group effect, all individual results were expressed relative to the mean value found in animals of the same gender, same strain, same nutritional situation and same glycemic status, such results being referred to as normalized values. Significant positive correlations were observed between the normalized values for the C22:6ω3 relative weight content of liver and plasma PL and, after exclusion of 2 female control rats with an abnormally high brain/plasma PL C22:6ω3 ratio, plasma and brain PL. Noticeably, the variation coefficients (SD/mean) for the 3 variables did not exceed 7.1±1.8%. A comparable situation prevailed between liver, plasma and brain triglycerides. Our results suggest that circulating PL participate in the transfer of C22:6ω3 from the liver to the brain, even in control and diabetic rats not deprived of a dietary source of long-chain polyunsaturated ω3 fatty acids.

The metabolic syndrome of ω3-depleted rats. IV. Intestinal phospholipid ω3 fatty acids

A dietary deprivation in long-chain polyunsaturated omega3 fatty acids initiated in 7-week old normal rats provokes within 3 to 7 months the appearance of several features of the metabolic syndrome. Likewise, within 2 to 4-5 weeks exposure to a flaxseed oil-enriched diet, these anomalies are rapidly corrected. The present study deals with the omega3 fatty acid content of intestinal phospholipids under the same experimental conditions. For the sake of comparison, the control rats were given access during the last 4-5 weeks to either a soybean or flaxseed oil-enriched diet. In control rats, the relative weight content of omega3 fatty acids as well as their product/precursor ratio differed in distinct segments of the intestinal tract (duodenum, jejunum, caecum, colon). Within 3 months of omega3-deprivation, the intestinal content of C18:3omega3, C20:5omega3 and C22:5omega3 reached values below the limit of detection, whilst the C22:6omega3 content progressively decreased down to 10-20% of control values. Within 2 weeks of exposure to the omega3-rich diet, the C18:3omega3, C20:5omega3 and C22:5omega3 content of intestinal phospholipids were higher than control values, whilst that of C22:6omega3 progressively returned to a normal level during the 2 to 4-5 weeks exposure to the flaxseed oil-enriched diet. The results collected in the intestinal cells, which are the first cells exposed to each given diet, reinforce the view that the present animal model is quite suitable to assess the metabolic consequences of both omega3 fatty acid deprivation and replenishment.

Alteration of lipid fatty acid profile and cationic fluxes in ventricular cardiomyocytes from ω3-depleted rats

The bolus intravenous injection of a medium-chain triglyceride:fish oil emulsion was recently found to increase within 60 min the cell phospholipid content in long-chain polyunsaturated omega3 fatty acids and, hence, proposed as a potential tool to prevent cardiac arrhythmia in subjects with a decreased dietary intake of such fatty acids. In the present study, ventricular cardiomyocytes from second generation rats depleted in omega3 fatty acids were found to display the same changes in the phospholipid fatty acid pattern as that previously documented in the cardiac muscle and endothelium of such rats, altered 86Rb and 45Ca fluxes with emphasis on a decrease in both K+ inflow and K+ content and an increase in both Ca2+ inflow and content. The alteration of K+ inflow could not be attributed to a decrease in ouabain-sensitive Na+,K+-ATPase activity as measured in cell homogenates. The cationic alterations were corrected, in part at least, by the prior intravenous injection of the medium-chain triglyceride:fish oil emulsion 60 min before sacrifice of the omega3-depleted rats.

The metabolic syndrome of ω3-depleted rats. II. Body weight, adipose tissue mass and glycemic homeostasis

Exposure of 7-week-old normal rats for 3-7 months to a diet deprived of long-chain polyunsaturated omega3 fatty acids was recently reported to induce changes in the fatty acid content and pattern of liver phospholipids and triglycerides similar to those otherwise found in second generation omega3-depleted rats. In the present study, the changes in body weight, parametrial adipose tissue mass, plasma glucose and insulin concentrations and insulin resistance index were investigated in the same control and omega3-depleted rats, which were then given access for 2 to 4-5 weeks to either a flaxseed oil-enriched diet (control and omega3-depleted rats) or a soybean oil-enriched diet (control rats). The body weight failed to differ between control and omega3-depleted rats. The latter rats, however, displayed increases in adipose tissue mass, plasma glucose and insulin concentrations, and insulin resistance index. In the control rats given access to the soybean or flaxseed oil-enriched diet, body weight and adipose tissue mass were little affected, but both the plasma glucose concentration and insulin resistance index decreased. In the omega3-depleted rats given access to the flaxseed oil-enriched diet, both body weight and adipose tissue mass underwent a rapid, pronounced and sustained increase, whilst the plasma glucose concentration and insulin resistance index decreased similarly to those in the control rats. The present design of omega3 fatty acid dietary deprivation thus reproduces the visceral obesity and insulin resistance otherwise observed in second-generation omega3-depleted rats. However, the supply of exogenous omega3 fatty acids to the omega3-depleted rats failed to oppose visceral obesity, possibly as a result of the orexigenic effects of these omega3 fatty acids.

Assessment of Safety, Nutritional, and Spoilage Characteristics of Different Lagoon Grey Mullets (Liza ramada, Liza aurata, and Liza saliens)

Different lagoon grey mullets such as Liza ramada (thinlip mullet), Liza aurata (golden grey mullet), and Liza saliens (leaping grey mullet) were analyzed for their nutritional, microbiological, and safety parameters. The microbiological values never exceeded the lower limits stipulated by the Italian Higher Institute of Health. The pathogenic species frequently associated with seafood (Salmonella, Listeria monocytogenes, Vibrio cholerae, Vibrio parahaemolyticus, and Aeromonas hydrophila) were never detected. The absence of coliforms and of Escherichia coli was noted in all fish species after 4 days of storage in ice. Heavy metals such as cadmium and mercury were always below the detection limits (0.01 mg/kg). All three fish species had low levels of total biogenic amines (80 to 100 mg/kg), and the presence of histamine was sporadic. All Liza species, particularly L. ramada and L. saliens, are a good source of Ω3 long-chain polyunsaturated fatty acids.

Rapid lipid enrichment in ω3 fatty acids: Liver data

The bolus intravenous injection of a novel medium-chain triglyceride:fish oil emulsion to normal subjects was recently reported to enrich within 60 min the phospholipid content of leucocytes and platelets in long-chain polyunsaturated omega3 fatty acids. The present study, conducted in second generation omega3-depleted rats, aimed at investigating whether such a procedure may also increase within 60 min the phospholipid content of omega3 fatty acids in cells located outwards the bloodstream, in this case liver cells, and whether this coincides with correction of the perturbation in the liver triglyceride fatty acid content and profile otherwise prevailing in these rats. This first report deals mainly with the fatty acid pattern of plasma lipids in male omega3-depleted rats that were non-injected or injected with either the omega3-rich emulsion or a control medium-chain triglyceride:olive oil emulsion. The results provide information on the fate of the exogenous lipids present in the lipid emulsions and injected intravenously 60 min before sacrifice. Moreover, in the uninjected omega3-depleted rats the comparison between individual plasma and liver measurements indicated positive correlations in the fatty acid profile of phospholipids and triglycerides.

Rapid lipid enrichment in ω3 fatty acids: Cause-to-effect relationships

The bolus intravenous administration of a novel medium-chain triglyceride:fish oil emulsion to second generation rats depleted in long-chain polyunsaturated omega3 fatty acids was recently found to enrich within 60 min the content of both plasma and liver lipids in such omega3 fatty acids, this coinciding with correction of the perturbation in liver triglyceride fatty acid content and profile otherwise prevailing in these rats. The present report draws attention to cause-to-effect relationships between changes in liver phospholipid and triglyceride fatty acid content and/or pattern operative under these experimental conditions.