Retinal sensitivity loss in third-generation n-3 PUFA-deficient rats

A previous study conducted in guinea pigs suggested that ingestion of diets high in EPA and DHA may result in suboptimal retinal function. The aim of the present study was to evaluate retinal function in pigmented (Long-Evans) rats, raised to a third generation on diets that were either deficient in n-3 PUFA or adequate (with the addition of DHA). Electroretinographic assessment employed full-field white flash stimulation. Photoreceptor responses were evaluated in terms of peak amplitudes and implicit times (a-wave, b-wave), intensity-response functions (Naka-Rushton), and the parameters of a model of transduction (P3). Retinal phospholipid FA composition was measured by capillary GLC. DHA levels were reduced by 55% in n-3-deficient animals compared with the n-3-adequate group, whereas the levels of docosapentaenoic acid n-6 were 44 times higher in n-3-deficient animals. The level of arachidonic acid was marginally higher (12.8%) in n-6-adequate animals. The n-3-deficient animals exhibited significantly reduced retinal sensitivity (σ and S values were both affected by 0.29 log units) and increased b-wave implicit times compared with those fed the n-3-adequate diet. These data suggest that n-3 PUFA are required for development of retinal sensitivity, more so than other indices of retinal function assessed by current methods, such as maximal response amplitude. However, the benefit for retinal function of adding preformed DHA to diets already replete in n-3 PUFA remains unclear.

Lipid characterisation of different tissues and fillet portions of intensively farmed Murray Cod Maccullochella peelii peelii

Although many studies have focused on the lipid and fatty acids composition of farmed fish, no many have investigated their deposition pattern in different portions of the fillet. Previous studies, mainly on salmonids, have shown that lipids distribution varies greatly depending on the species, portion and type of muscle, but nevertheless, there is not accurate description of its deposition pattern in many fish, in particular in warm water, freshwater carnivorous species. Murray cod is the largest Australian native freshwater carnivorous fish and supports a small but well established and fast growing industry. The objective of this study was therefore to determine if there was any difference in lipid and fatty acid in different tissues such as muscle, liver and perivisceral fat and in different portions of the fillet of farmed Murray cod.

Three size fish (small, medium and large), all fed the same commercial diet, were selected from a commercial intensive farm. The left fillet of each fish was sectioned into nine portions, according to muscle lines and main anatomical features. The nine portions as well as whole right fillet, liver and perivisceral fat were analysed for proximate and fatty acid composition (Table 1).

Differences in lipid content were found amongst different portions of the fillet, with the dorsal/cranial portion (P1) recording the lowest and the more ventral/caudal portion (P8) recording the highest (P<0.05) value. The latter also recorded the highest amount of monounsaturated fatty acid (MUFA) and the lowest of polyunsaturated fatty acids (PUFA), arachidonic acid, 20:4n-6 (ArA), docosahexaenoic acid, 22:6n-3, (DHA) and n3/n6 ratio. In general, lipid content in the different fillet portions was inversely correlated to PUFA and directly to MUFA. Saturated fatty acid (SFA) and eicosapentaenoic acid, 20:5n-3 (EPA) did not show any discernible trend and were similar throughout, while significant differences of DHA and ArA content were observed. This study shows that lipid deposition in Murray cod varies remarkably and that different fatty acids are deposited at different rates. The results of this study show how different adjacent portions can be and therefore attention need to be paid when conducting chemical, nutritional and sensorial analyses on Murray cod.

The role of omega-3 fatty acids in mood disorders

Research has established that docosahexaenoic acid (DHA), a long-chain omega-3 polyunsaturated fatty acid (PUFA), plays a fundamental role in brain structure and function. Epidemiological and cross-sectional studies have also identified a role for long-chain omega-3 PUFA, which includes DHA, eicosapentaenoic acid, and docosapentaenoic acid, in the etiology of depression. In the past ten years, there have been 12 intervention studies conducted using various preparations of longchain omega-3 PUFA in unipolar and bipolar depression. The majority of these studies administered long-chain omega-3 PUFA as an adjunct therapy. The studies have been conducted over 4 to 16 weeks of intervention and have often included small cohorts. In four out of the seven studies conducted in depressed individuals and in two out of the five studies in bipolar patients, individuals have reported a positive outcome following supplementation with ethyl-eicosapentaenoic acid or fish oil containing long-chain omega-3 PUFA. In the three trials that researched the influence of DHA-rich preparations, no significant effects were reported. The mechanisms that have been invoked to account for the benefits of long-chain omega-3 PUFA in depression include reductions in prostaglandins derived from arachidonic acid, which lead to decreased brain-derived neurotrophic factor levels and/or alterations in blood flow to the brain.

The role of eicosanoids in the brain

The brain contains two main polyunsaturated fatty acids (PUFA), arachidonic acid (AA) and docosahexaenoic acid (DHA). These PUFA are located almost exclusively in the sn2-position of phosphoglycerides which are found in the neural cell membranes. Liberation of these PUFA from the phosphoglycerides occurs via the action of specific phospholipases (PLA2). Free AA can be metabolised by cyclooxygenases to prostaglandins and  thromboxane, while both AA and DHA can be metabolised by lipoxygenases to form hydroxy derivatives and leukotrienes. AA is also metabolised to  lipoxins via the 5-lipoxygenase pathway. The eicosanoids formed play important roles in neural function including sleep induction (PGD2), long  term potentiation, spatial learning and synaptic plasticity (PGE2), resolution of inflammation (lipoxins) and anti-inflammatory and neuroprotective  bioactivity (dihydroxy-docosatriene, neuroprotectin D1, formed from DHA). COX-inhibitors have been shown to reduce oxidative stress and cognitive impairment. Additionally, drugs which are used to treat depression have been shown to reduce the turnover of AA to PGE2 in the brain. Diets deficient in omega 3 PUFA lead to reduced DHA in the brain and increased turnover of AA to eicosanoids, an effect which is overcome by restoring the omega 3 PUFA to the diet. In neural trauma and neurodegenerative diseases, there is a dramatic rise in the levels of AA-derived eicosanoids. In contrast,  DHA-derived compounds can prevent neuroinflammation. Clearly, the eicosanoids are very important for the normal functioning of the brain, while the PUFA themselves are important in membrane structure and function.

Habitual fish consumption does not prevent a decrease in LCPUFA status in pregnant women (the Seychelles Child Development Nutrition Study)

Information on the status of long-chain polyunsaturated fatty acids (LCPUFAs) in pregnancy and breast milk in very high fish-eating populations is limited. The aim of this study was to examine dietary intake and changes in fatty acid status in a population of pregnant women in the Republic of Seychelles. Serum docosahexaenoic acid (DHA) decreased significantly between 28-week gestation and delivery (n=196). DHA status did not correlate significantly with length of gestation and was not associated with self-reported fish intake, which was high at 527 g/week. In breast milk, the ratio of DHA to arachidonic acid (AA) was consistent with those observed in other high fish-eating populations. Overall the data suggest that high exposure to LCPUFAs from habitual fish consumption does not prevent the documented decrease in LCPUFA status in pregnancy that occurs as a result of foetal accretion in the third trimester of pregnancy.

Substrate specificity, regulation, and polymorphism of human cytochrome P450 2B6

CYP2B6 is mainly expressed in the liver that has been thought historically to play an insignificant role in human drug metabolism. However, increased interest in this enzyme has been stimulated by the discovery of polymorphic and ethnic differences in CYP2B6 expression, identification of additional substrates for CYP2B6, and evidence for co-regulation with CYP3A4. This paper updates our knowledge about the structure, function, regulation and polymorphism of CYP2B6. CYP2B6 can metabolise approximately 8% of clinically used drugs (n > 60), including cyclophosphamide, ifosfamide, tamoxifen, ketamine, artemisinin, nevirapine, efavirenz, bupropion, sibutramine, and propofol. CYP2B6 is one of the CYP enzymes that bioactivate several procarcinogens and toxicants. This enzyme also metabolizes arachidonic acid, lauric acid, 17beta-estradiol, estrone, ethinylestradiol, and testosterone. Typical substrates of CYP2B6 are non-planar molecules, neutral or weakly basic, highly lipophilic with one or two hydrogen-bond acceptors. The crystal structure of CYP2B6 has not been resolved, while several pharmacophore and homology models of human CYP2B6 have been reported. Human CYP2B6 is closely regulated by constitutive androstane receptor (CAR/NR1I3) which can activate CYP2B6 expression upon ligand binding. Pregnane X receptor and glucocorticoid receptor also play a role in the regulation of CYP2B6. Induction of CYP2B6 may partially explain some clinical drug interactions observed. For example, coadministered carbamazepine decreases the systemic exposure of bupropion. There is a wide interindividual variability in the expression and activity of CYP2B6. Such a large variability is probably due to effects of genetic polymorphisms and exposure to drugs that are inducers or inhibitors of CYP2B6. To date, at least 28 allelic variants and some subvariants of CYP2B6 (*1B through *29) have been described and some of them have been shown to have important functional impact on drug clearance and drug response. For example, the efavirenz plasma levels in African-American subjects with the CYP2B6 homozygous 516T/T genotype are approximately 3-fold higher than individuals carrying the homozygous G/G genotype. The CYP2B6 516T/T genotype is associated with 1.7-fold greater plasma levels of nevirapine in HIV-infected patients. Smokers with the 1459C>T (R487C) variant of CYP2B6 may be more vulnerable to abstinence symptoms and relapse following treatment with bupropion as a smoking cessation agent. Further studies in the structure, function, regulation and polymorphism of CYP2B6 are warranted.

Reproductive development, GnRHa-induced spawning and egg quality of wild meagre (Argyrosomus regius) acclimatised to captivity

The objective of the study was to acclimatise wild-caught meagre (Argyrosomus regius) to captivity to produce viable eggs for aquaculture production. Twelve meagre (3 males and 9 females, mean weight = 20 ± 7 kg) were caught and transported to a land-based facility on 26 October 2006. During, March to June 2007, all three males were spermiating and five of the nine females were in vitellogenesis with mean maximum oocyte diameter ≥550 μm. No spontaneous spawning was observed. Two hormone treatments, either a single injection of gonadotropin-releasing hormone agonist (GnRHa, 20 μg kg−1 for females and 10 μg kg−1 for males) or a slow-release implant loaded with the same GnRHa (50 μg kg−1 for females and 25 μg kg−1 for males), were used to induce spawning on three different dates on 26 March 2007, 4 May 2007 and 18 April 2008. From each spawning event, the following parameters were determined: fecundity, number of floating eggs, egg size, fertilisation and hatching success, unfed larval survival, and proximal composition and fatty acid profile of the eggs. In 2007, two females that were injected on 26 March and 4 May spawned a total of 5 times producing 9,019,300 floating eggs and a relative fecundity of 198,200 eggs kg−1 and two different females that were implanted on the same dates spawned 14 times producing 12,430,000 floating eggs and a relative fecundity of 276,200 eggs kg−1. In 2008, a pair that was implanted spawned five times producing a total of 10,211,900 floating eggs and a relative fecundity of 527,380 eggs kg−1. The latency period was 48–72 h. Parameters were compared between hormone treatments, date of hormone induction and parents determined by microsatellites. Percentage hatch and egg size were 70 ± 0.3% and 0.99 ± 0.02 mm, respectively, for GnRHa-implanted fish and were significantly higher (P < 0.05) compared to 30 ± 0.3% and 0.95 ± 0.03 mm, respectively, for injected fish. Few differences were observed in proximal composition and fatty acid profile and for all spawns mean (% dry weight) lipid content was 17.3 ± 3.0%, carbohydrate was 4.4 ± 1.9% and protein was 31.5 ± 6.4% and the essential fatty acids: Arachidonic acid (ARA, 20:4n-6) ranged between 0.9 and 1% (of total fatty acids), eicosapentaenoic acid (EPA 20:5n-3) 7.7–10.4% and docosahexaenoic acid (DHA 22:6n-3), 28.6–35.4%. All good quality spawns were obtained in the second and/or third spawn after GnRHa treatment, whereas all bad quality spawns were obtained either on the first spawn or after the fifth spawn. Both spawning protocols gave commercially viable (1,000,000+) numbers of good quality eggs that could form the basis of a hatchery production.

Human inflammatory and resolving lipid mediator responses to resistance exercise and ibuprofen treatment

Classical proinflammatory eicosanoids, and more recently discovered lipid mediators with anti-inflammatory and proresolving bioactivity, exert a complex role in the initiation, control, and resolution of inflammation. Using a targeted lipidomics approach, we investigated circulating lipid mediator responses to resistance exercise and treatment with the NSAID ibuprofen. Human subjects undertook a single bout of unaccustomed resistance exercise (80% of one repetition maximum) following oral ingestion of ibuprofen (400 mg) or placebo control. Venous blood was collected during early recovery (0–3 h and 24 h postexercise), and serum lipid mediator composition was analyzed by LC-MS-based targeted lipidomics. Postexercise recovery was characterized by elevated levels of cyclooxygenase (COX)-1 and 2-derived prostanoids (TXB2, PGE2, PGD2, PGF2α, and PGI2), lipooxygenase (5-LOX, 12-LOX, and 15-LOX)-derived hydroxyeicosatetraenoic acids (HETEs), and leukotrienes (e.g., LTB4), and epoxygenase (CYP)-derived epoxy/dihydroxy eicosatrienoic acids (EpETrEs/DiHETrEs). Additionally, we detected elevated levels of bioactive lipid mediators with anti-inflammatory and proresolving properties, including arachidonic acid-derived lipoxins (LXA4 and LXB4), and the EPA (E-series) and DHA (D-series)-derived resolvins (RvD1 and RvE1), and protectins (PD1 isomer 10S, 17S-diHDoHE). Ibuprofen treatment blocked exercise-induced increases in COX-1 and COX-2-derived prostanoids but also resulted in off-target reductions in leukotriene biosynthesis, and a diminished proresolving lipid mediator response. CYP pathway product metabolism was also altered by ibuprofen treatment, as indicated by elevated postexercise serum 5,6-DiHETrE and 8,9-DiHETrE only in those receiving ibuprofen. These findings characterize the blood inflammatory lipid mediator response to unaccustomed resistance exercise in humans and show that acute proinflammatory signals are mechanistically linked to the induction of a biological active inflammatory resolution program, regulated by proresolving lipid mediators during postexercise recovery.

Dietary n-6/n-3 LC-PUFA ratio, temperature and time interactions on nutrients and fatty acids digestibility in Atlantic salmon

The objective of the present study was to evaluate the effects of altered dietary n-3/n-6 LC-PUFA ratio, adaptation to diet over time, different water temperatures, and their interactions on nutrients and fatty acids digestibility in juvenile Atlantic salmon. Three experimental diets were formulated to be identical, with the only exception of the ratio of eicosapentaenoic acid (EPA, 20:5n-3) to arachidonic acid (ARA, 20:4n-6), and fed to triplicate groups of juvenile Atlantic salmon (Salmo salar) of 55. g initial body weight. Fish were reared in a fully controlled recirculating aquaculture system, fed to apparent satiety twice daily and kept at 10. °C and for an initial period of 100. days, and faeces were collected for digestibility estimation. Then, half of the fish of each experimental tank were moved to a separate system, where the water temperature was gradually increased up to 20. °C. Fish were maintained in the two systems for an additional period of 50. days, and faeces were collected for digestibility estimation from both groups of fish at the two water temperatures. This study concluded that dietary treatments and time had only minor effects, whereas environmental temperature resulted in modified digestibility values, with increased nutrient digestibility with increasing temperature. Varying EPA/ARA ratio in the diet had only minor direct effects on digestibility, with no direct effect on overall nutrients digestibility, and fundamentally only statistically significant effects in the fatty acid digestibility of EPA and ARA themselves. Because of current increasing pressure for more efficient fish oil replacement strategies, increasing interest in dietary ARA in aquafeed and increasing relevance and occurrence of sub-optimal rearing temperature in commercial aquaculture, this study can be considered to be important as it provided a series of fundamental information, which are envisaged to be useful towards addressing these constraints and possible nutritional remedial strategies.

Solvent-induced 7R-dioxygenase activity of soybean 15-lipoxygenase-1 in the formation of omega-3 DPA-derived resolvin analogs

The resolvin family contains important anti-inflammatory and pro-resolution compounds enzymatically derived in vivo from the polyunsaturated omega-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). More recently, docosapentaenoic acid (DPA) has emerged as another potentially important precursor in the biological production of resolvin compounds. In this work we have used medium engineering to develop a simple method for the controlled synthesis of two di-hydroxylated diastereomers of DPAn-3 catalyzed by soybean 15-lipoxygenase-1 (15-sLOX-1) in the presence of short chain n-alcohols, including methanol, ethanol and propan-1-ol. The complete structures of the two major products, 7S,17S-dihydroxydocosapenta-8Z,10E,13Z,15E,19Z-enoic acid (7S,17S-diHDPAn-3) and 7R,17S-dihydroxydocosapenta-8Z,10E,13Z,15E,19Z- enoic acid (7R,17S-diHDPAn-3), have been elucidated using spectroscopic analysis. The alcohol-dependent R-dioxygenase activity of soybean 15-lipoxygenase with mono-hydroperoxide intermediate substrates has also been demonstrated with other biologically relevant PUFAs, including DHA, EPA and ARA. The developed method has applications in the production of closely related isomers of naturally occurring resolvins and protectins, demonstrating the versatility of 15-sLOX-1 as a biocatalyst. © 2014 Elsevier B.V.

Towards the optimization of performance of Atlantic salmon reared at different water temperatures via the manipulation of dietary ARA/EPA ratio

In recent years, aquaculture has been facing a series of new issues, including the necessary replacement of fish oil and fish meal because of their limited supply and sub-optimal water temperature conditions. Higher water temperatures are increasingly encountered as the result of climate change related phenomena and/or the practice of farming of species in areas with environmental characteristics outside their optimal physiological range, such as the case of Atlantic salmon (. Salmo salar) farming in Australia during the summer season. Previous studies in teleost fish have shown that when fish are exposed at higher environmental temperatures, fish had a preferential increased dietary intake for arachidonic acid (20:4n - 6, ARA). This observation suggests that, given the several metabolic roles of ARA, its dietary provision may play an important role in fish for adapting at sub-optimal high water temperatures. The objective of this study was therefore to evaluate the effects of different dietary ARA/EPA ratios in juvenile Atlantic salmon as affected by time of exposition to the diet and water temperatures, with particular focus to fish performance and possible resulting modifications of tissue fatty acid composition. The study showed that independently from dietary treatments, fish held at the higher temperatures had an increased ARA accumulation, primarily in the liver and this ARA accumulation increased over time. It was also shown that the combined dietary inclusion of ARA and EPA significantly improved fish performance, compared with diets either richer in ARA or EPA. A general trend toward higher content of n - 3 LC-PUFA at lower temperatures was also quite clear, especially in the liver. Therefore, and assuming that the trends in tissue fatty acid composition could be taken as a clue of the optimal fatty acid requirements of fish, the n - 6 requirement (and in particular ARA) clearly appears to be greater for Atlantic salmon raised at high water temperatures. Protein accumulation was higher in the diet with the combined dietary inclusion of ARA and EPA for fish held at high water temperature (20. °C), with a concomitant lipid reduction. This study shows the importance of dietary ARA for maximal growth in Atlantic salmon, particularly during the period of the year when high water temperatures are often encountered. Further studies specifically looking at optimal dietary ARA/EPA ratio and roles of ARA on myogenesis, stress physiology and immune status of cultured fish are warranted. Statement of relevance: Given the current high level of fish oil replacement in aquafeed, and the often encountered sub-optimal environmental temperatures, we believe that this study could be considered as timely and highly pertinent for the aquaculture industry and associated R&D sector.

Harpalycin 2 inhibits the enzymatic and platelet aggregation activities of PrTX-III, a D49 phospholipase A(2) from Bothrops pirajai venom

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Quercetin as an inhibitor of snake venom secretory phospholipase A2

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Quality of polyunsaturated fatty acids in Nile tilapias (Oreochromis niloticus) fed with vitamin E supplementation

Freshwater fish are an important source of protein, but they also contain other highly nutritive components such as fats. Polyunsaturated fatty acids (PUFAs) are essential for normal growth, development and reproduction of vertebrates. The antioxidant role of vitamin E in cell membranes prevents fatty acid and cholesterol oxidation, thereby promoting PUFA and subcellular particle stabilization. The effects of vitamin E supplementation on the quality of Nile tilapia (Oreochromis niloticus) carcass were investigated. The experiments were carried out in an experimental laboratory over 106 d. After sex reversal, 400 early juvenile O. niloticus were tested in a completely randomized experiment with 5 treatments (4 repetitions each), consisting of vitamin E monophosphate supplementation at 0, 50, 100, 150 or 200 mg/kg of a base diet. Treatment diets contained equal amounts of protein and energy. Tilapias supplemented with vitamin E contained arachidonic acid (20:4 omega-6; AA) which participates in inflammatory response. Nile tilapia carcasses that received vitamin E at 100 and 150 mg/kg diet had improved carcass quality by increasing the PUFA:SFA ratio and had the highest levels of polyunsaturated fatty acids from the omega-3 (linolenic acid; 18:3 omega-3) and omega-6 (linoleic acid; 18:2 omega-6) series. (C) 2012 Elsevier Ltd. All rights reserved.

Expressão imuno-histoquimica da cicloxigenase-2 e p53 em cancinoma epidermóide oral

Squamous cell carcinoma is the most common malignant neoplasm in the oral cavity, accounting for more than 90% of all malignancies in this location. Cyclooxygenases (COX s) are key enzymes on arachidonic acid metabolism and prostaglandin synthesis, being expressed basically in two forms: the constitutive (COX-1) and the inducible (COX-2). Increased levels on the expression of COX-2 have been implicated in the pathogenesis tumor progression of various forms of human cancer, including oral squamous cell carcinoma, some of what suggesting a possible interaction between COX-2 and the protein expressed by the tumor suppressor gene p53, mutated in more than 50% of all human cancers. The mean of the present research consisted in analyze the correlation between the expression of COX-2 and p53, at the protein level, as well as evaluate the difference on the expression of these two proteins with the histological grading of malignancy. 34 cases of oral squamous cell carcinoma were selected and graded according to the histological grading system proposed by Bryne (1998) and the labeling indexes (LI s) for COX-2 and p53 evaluated using immunohistochemistry method. The results revealed that COX-2 was expressed in increased levels in most of the specimens, although there was no statistic significant correlation between LI s from COX-2 and p53 (p>0.05), and there were no statistical differences on the expression of these proteins between tumors of high and low grade of malignancy (p>0.05). Interestingly, the expression of COX-2 and p53 was detected in fragments of dysplastic oral epithelium adjacent to tumor areas, on basal and suprabasal layers. The absence of statistical correlation between the expression of COX-2 and p53 proteins do not rule ot the existence of a relation between them, were it may reflect the diversity of regulatory pathways between both, different direct and indirect inhibitory effects of COX-2 over p53, as well as the wide range of activation macheenisms for COX-2 and mutational status of the p53 gene Another conclusion point that the increased expression of COX-2 observed in oral squamous cell carcinomas suggest a role for this protein in the processes of pathogenesis and tumoral evolution of this malignant neoplasm