La composition en acides gras du tissu adipeux mammaire est reconnue comme marqueur qualitatif de la consommation lipidique antérieure mais aussi de la part nutritionnelle du risque / pronostic du cancer du sein. Ceci ouvre la perspective d’individualiser dans la population générale, un groupe de personnes à risque, susceptibles de bénéficier d’une intervention nutritionnelle ciblée. L’approche du dépistage d’une population à risque par l’utilisation de la composition du tissu adipeux comme biomarqueur se heurte i) à l’aspect invasif que représente le prélèvement d’un fragment de tissu adipeux mammaire, et ii) à la lourdeur contraignante du conditionnement et de l’analyse systématique des acides gras du tissu adipeux. Les méthodes analytiques actuellement disponibles sont incompatibles avec la perspective d’un dépistage de masse. Cependant, les descriptions récentes de l’utilisation de la spectroscopie par résonance magnétique (SRM) pour décrire la composition lipidique des triglycérides du tissu adipeux permettent d’envisager de l’utiliser dans cet objectif. Ce travail de thèse présente: 1) l’évaluation de la SRM pour caractériser la composition en acides gras du tissu adipeux chez l’animal (le rat) suite à une intervention nutritionnelle, 2) l’évaluation du profil lipidique du tissu adipeux par SRM chez la femme sur une plateforme clinique 3T, 3) l’étude des liens entre la composition en acides gras du tissu adipeux et la présentation du cancer du sein, et 4) la comparaison des données de la SRM in vitro (11.7T) et in vivo (3T) du tissu adipeux chez des patientes prises en charge pour un cancer du sein avec les données de la chromatographie gazeuse. / Fatty acid composition of the white adipose tissue remains the most reliable qualitative biomarker of previous dietary intake of fatty acids and may provide information on the nutritional part of the risk or evolution of breast cancer. This opens the prospect of individualization of women at high nutritional risk of breast cancer that may benefit from a targeted nutritional intervention but 1) the need for biopsy and 2) subsequent time-consuming biochemical analyses hamper any application of this approach. Proton magnetic resonance spectroscopy (1H-MRS) of adipose tissue lipids represents an appealing, non-invasive approach, which could circumvent these limitations. This manuscript reports: 1) an assessment of feasibility of (1H-MRS) to evaluate the consequences of a nutritional intervention in a rat mammary tumor model on the adipose tissue fatty acid composition, 2) an assessment of the feasibility of in vivo measurement of the fatty acid composition of breast adipose tissue by (1H-MRS) on a clinical platform, 3) an assessment of the relation of specific patterns of composition of adipose tissue fatty acids with the presentation of breast cancer, and 4) a comparison with gas chromatography of (1H-MRS) data acquired on breast adipose tissue in vitro (11.7T) and in vivo (3T) on patients managed for breast cancer.

Obesity is tightly connected with metabolic diseases including insulin resistance, type 2 diabetes or dyslipidemia. Peroxisome proliferator-activated receptor (PPAR)-α is a key transcription factor involved in the regulation of lipid metabolism, while its activity is stimulated by a variety of hypolipidemic drugs. n-3 polyunsaturated fatty acids (PUFA), including eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid, are endogenous ligands of PPARα, and they are used in the form of fish oil as dietary supplements in order to lower blood lipid levels and to prevent cardiovascular disease. Wax esters represent a novel lipid form of EPA and DHA, and according to recent studies they could exert more potent effects than the classical fish oil (i.e. triacylglycerols). Mice of the 129S1/SvImJ inbred strain were used in the present experiment, and included wild-type (WT) mice, as well as transgenic mice either with the exclusive expression of the human form of PPARα (hPPARα) or mice completely lacking PPARα (PPARα-KO). Mice were fed for 8 weeks the following diets: (i) a control low-fat diet, (ii) obesogenic high-fat diet (cHF), and (iii) the cHF diet supplemented with the n-3 PUFA concentrate in the form of wax esters isolated from marine zooplankton Calanus finmarchicus (ω3Cal). Mice were subjected to...

Les accidents cardio-vasculaires représentent la première cause de décès en France. Parmi les facteurs de risque de ces pathologies figure la structure de l’apport lipidique, excédentaire en acides gras saturés, et déficitaire en acides gras polyinsaturés n-3. L’objectif de cette thèse est la mise au point d’un corps gras alimentaire, dont le profil lipidique permet de participer au rééquilibrage des apports en acides gras, avec comme cible la prévention des maladies cardio-vasculaires.Quatre études ont été réalisées pour répondre à cette problématique. Après la mise au point du profil en acides gras optimal, l’impact de la formulation de la phase concrète sur la texture du produit a été étudié afin de concilier les exigences nutritionnelles et les contraintes techniques de sa fabrication et de sa conservation.La mise au point de la formulation de la phase fluide a engendré une étude sur le développement de composés volatils délétères suite à l’addition d’une proportion importante d’huile de poisson dans la formule. Ce travail a mis en évidence deux phénomènes liés au dégagement de ces molécules, l’un attribué à l’oxydation des lipides, l’autre au contact avec l’eau.Le besoin de protéger les nutriments d’intérêt dans la matrice alimentaire a conduit à la mise au point d’une technologie de microencapsulation, originale de par son procédé de fabrication et sa finalité.Enfin, une étude de la biodisponibilité chez l’animal a montré que ce produit alimentaire est un vecteur efficace de ces nutriments d’intérêt que sont les acides gras polyinsaturés à longue chaîne. Apportés dans une telle matrice, ces composés ont modifié le profil lipidique des cellules circulantes et cérébrales, ce qui permet potentiellement d’améliorer le statut inflammatoire et coagulant des animaux / Cardiovascular events are the major cause of death in France. Among the known risk factors, lipid intake is of growing interest, saturated fatty acids being too much consumed, and n-3 polyunsaturated fatty acids not enough. The aim of this PhD study is to design a spread with a lipid profile that can improve the whole lipid intake, and with cardiovascular events prevention as main goal.Four studies were conducted regarding this issue. Following the design of the optimal fatty acid profile for the product, it appeared necessary to study the solid phase recipe impact on the product texture, to achieve both nutritional and technological restrains.The design of the liquid phase recipe generated a study on the development of deleterious volatile compounds following the addition of a high proportion of fish oil in the formula. This work highlighted two phenomena linked to the emission of these molecules, one related to lipid oxidation, and the other to a contact with water.A technology of microencapsulation, which is original because of its production process and aim, was designed to ensure the protection of the active nutrients in the product matrix.Finally, a bioavailability study in rats showed that this food product is a powerful way of providing these nutrients. Incorporated in such a matrix, these molecules modified the lipid profile of the circulating and cerebral cells membrane, potentially improving the inflammatory and clotting status of the animals

Regulation of the flow of fatty acids (FA) by futile cycle (TAG/FA cycle) in white adipose tissue (WAT) is an important mechanism of controlling metabolism of FA and therefore its regulation is in the interest of research as a possible therapeutic target in the treatment of obesity and insulin resistance. The study of the murine model suggests that the treatment of the n-3 PUFA with mild caloric restriction (CR) probably induces the TAG/FA cycle mainly in epididymal depot. It also reduces inflammation in WAT and the risk of cardiovascular diseases. We focused on monitoring the gene expression encoding key enzymes of the TAG/FA cycle (PEPCK, ATGL, HSL, DGAT1 and DGAT2) in dorzolumbar (DL), gonadal (GON) and mesenteric (MEZ) depot in a murine model C57BL/6 using qPCR. We were interested in the influence of the composition of fats in the diet, the influence of administration of n-3 PUFA with combination of 10% CR and the difference of gene expression among depots of WAT. The results indicate that the supplementation of high-fat diet with n-3 PUFA contributes mainly to reduction of gene expression for DGAT2 and the combination of n-3 PUFA and CR increases expression of genes influencing the TAG/FA cycle. In MEZ unlike GON and DL fat depot were no significant differences in gene expression, while the different...

no / Human saphenous vein endothelial cells (HSVECs) derived from primary cultures of adult human veins constitute an excellent in vitro model for studying human endothelial metabolism. In this study we report the14C-labelled prostanoid profile of HSVECs under resting and stimulated conditions and the effect of the n-3 polyunsaturated fatty acids eicosapentaenoic acid and docosahexaenoic acid on them. Results indicate that HSVECs while under resting conditions produce mainly prostaglandin F2 ¿(PGF2 ¿). After stimulation with calcium ionophore A23187, the cells were found to synthesise PGI2, PGE2and PGF2¿as major products and thromboxane B2and PGD2as minor products. Production of14C-labelled hydroxyeicosatetraenoic acids was not detected. Eicosapentaenoic acid was found to inhibit basal and stimulated prostanoid production whereas docosahexaenoic acid inhibited basal but strongly increased stimulated prostanoid production. These results may offer the basis for further studies aiming to investigate targets for pharmacological intervention in inflammatory conditions.

La maladie d'Alzheimer (MA) est une démence neurodégénérative caractérisée par des pertes de la mémoire et des troubles cognitifs. La toxicité des oligomères solubles du peptide [bêta]-amyloïde (A[bêta]Os) est centrale dans la phase précoce de la maladie. L'absence de traitements curatifs, l'aspect chronique des mécanismes pathogéniques et le partage de facteurs de risque communs avec les pathologies cardiovasculaires, notamment les paramètres alimentaires et le métabolisme lipidique, doivent inciter à considérer l'intérêt de méthodes préventives permettant d'empêcher l'apparition de la maladie. Dès lors, l'approche nutritionnelle apparaît comme une stratégie capable de limiter sa prévalence. Une souris modèle des stades précoces de MA nous a permit d'évaluer le potentiel préventif d'une alimentation enrichie en acide docosahexaénoïque (DHA, C22:6, n-3). Les résultats obtenus montrent qu'un apport alimentaire suffisant en DHA conduit à en enrichir les membranes dans les différentes structures cérébrales. En conséquence, les fonctions synaptiques sont préservées, même après exposition aigüe aux A[bêta]Os, ce qui maintient les capacités cognitives des souris exposées. Nous avons ensuite développé des stratégies nutritionnelles permettant d'évaluer les effets bénéfiques de DHA contre la dyslipidémie induite par l'alimentation et les déficits cognitifs associés au vieillissement normal ou pathologique. Les résultats obtenus à l'issue de notre étude révèlent qu'un apport alimentaire en DHA est capable de prévenir la dyslipidémie provoquée par un régime riche en lipides et de retarder le déclin cognitif lié au vieillissement cérébral normal ou pathologique / Alzheimer's disease is a neurodegenerative aging-related dementia that is characterized by loss of memory and cognitive disorders. Toxicity of soluble oligomers of [beta]-amyloid peptide (sOA[beta]) is a key element in early stages of the disease. Absence of curative therapies, chronic aspects of the pathogenic mechanisms implicated and influence of common risk factors shared with the cardiovascular diseases, including dietary parameters and lipid metabolism, should widely encourage considering the interest of preventive interventions allowing slowing the progression and delaying the clinical onset of Alzheimer's-related troubles. Therefore, nutritional approaches could appear as a strategy able to reduce the prevalence of this disease. Early Alzheimer's mouse model allowed us to assess the preventive potential of diets supplemented in docosahexaenoic acid (DHA, C22:6 n-3). Our results show that adequate dietary intake of DHA lead to increased levels in different brain structures. Consequently, hippocampal and cortical synaptic functions were preserved, even upon acute exposure to A[beta] oligomers, maintaining or improving the cognitive capacities of A[beta]-exposed mice. These improvements were positively correlated with DHA-enrichment associated in hippocampus and with preserved synaptic integrity. We also designed nutritional strategies in order to evaluate the beneficial effects of DHA on diet-induced dyslipidemia as well as on cognitive impairment and neurodegenerative processes associated with normal or pathologic aging. Our results show that dietary DHA can prevent high-fat diet-induced dyslipidemia and delay cognitive decline related with normal or pathological aging

Les aliments riches en acides gras polyinsaturés (AGPI) à longue chaîne (LC) de la série n-3 sont recommandés pour leurs effets bénéfiques sur la santé humaine et en particulier dans la prevention du développement des maladies métaboliques. Or, la biodisponibilité de ces AGPI et leur impact métabolique pourraient être modulés par la nature chimique des molécules qui les véhiculent dans les aliments (triacylglycérols, TG ou phospholipides, PL). De plus, ces AGPI sont sensibles à la peroxydation lipidique. S’ils ne sont pas protégés de l’oxydation, ils peuvent former des espèces réactives toxiques comme le 4-hydroxy-hexénal (4-HHE). Dans ce contexte, le but de notre étude a été d’évaluer l’impact de l’enrichissement de régimes hyperlipidiques en AGPI n-3 (i) portés par des TG ou des PL et (ii) sous forme non-oxydée ou oxydée, sur l’inflammation et le stress oxydant métaboliques et d’en comprendre certains mécanismes liés à l’absorption intestinale et la réactivité du 4-HHE. D’une part, notre étude a confirmé que la consommation d’AGPI-LC n-3 empêche l’induction du stress oxydant et de l’inflammation lors d’un régime hyperlipidique chez la souris. Cependant, par rapport aux TG, les PL vecteurs d’AGPI n-3 permettent de réduire la taille des adipocytes et de stimuler le système antioxydant. D’autre part, notre étude a montré que la consommation d’AGPI n-3 oxydés de manière modérée aboutit à une élévation des concentrations plasmatiques de 4-HHE et des marqueurs inflammatoires. De plus, une activation des voies inflammatoires ainsi que du stress du réticulum endoplasmique ont été détectées au niveau de l’intestin grêle. Nos résultats in vivo et in vitro sur cellules intestinales Caco-2/TC7 indiquent que cela peut être dû en partie à une absorption au niveau intestinal du 4-HHE, produit d’oxydations des AGPI n-3. Dans le contexte du développement des aliments contenant des AGPI-LC n-3, nos résultats contribuent à identifier les structures vectrices de ces acides gras les plus efficaces du point de vue métabolique. En santé publique et en pratique clinique, nos résultats constituent une nouvelle base de réflexion pour la mise en place de bonnes pratiques de production et de conservation des aliments et des compléments nutritionnels enrichis en AGPI-LC n-3 pour éviter leur oxydation et ses possibles effets délétères. / Dietary intake of n-3 long chain (LC) polyunsaturated fatty acids (PUFA) are recommended for their beneficial effects on human health, especially to prevent the development of metabolic diseases. However, the bioavailability of these PUFAs and their metabolic impact could be modulated by their chemical carriers (triacylglycerols, TG or phospholipids, PL). In addition, these PUFA are susceptible to lipid peroxidation. If they are not protected from oxidation, they can form toxic reactive species such as 4-hydroxy-hexenal (4-HHE). In this context, the aim of our study was to evaluate the impact of enriching high-fat diets with n-3 PUFA (i) bound to TG or PL and (ii) in unoxidized or oxidized form on the generation of inflammation and oxidative stress, and to understand some underlying mechanisms associated with intestinal absorption and reactivity of 4-HHE. On the one hand, our study confirmed in mice that the consumption of n-3 PUFA protects against oxidative stress and inflammation induced by high-fat diets. However, compared to TG, n-3 PUFA in the form of PL reduce the size of adipocytes and stimulate the antioxidant system. On the other hand, our study showed that the consumption of moderately oxidized n-3 PUFA results in increased plasma concentrations of 4-HHE and of inflammatory markers. In addition, activation of inflammatory pathways as well as endoplasmic reticulum stress were detected in the small intestine. Our results in vivo and in vitro, using intestinal Caco-2/TC7 cells, indicate that this can be partly due to the intestinal absorption of the end-product of n-3 PUFA oxidation, 4-HHE. In the context of the development of foods containing LC n-3 PUFA, our results contribute to identify the most effective PUFA carriers on a metabolic standpoint. Regarding public health and clinical practice, our results provide new basis for the set up of best practices regarding production and storage of food and supplements enriched with LC n-3 PUFA to avoid their lipid oxidation and its possible deleterious effects.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Os ácidos graxos poli-insaturados n-3 derivados do óleo de peixe estão associados a benefícios cardiovasculares, que podem ser decorrentes da ativação da óxido nítrico sintase (NOS). Assim como as células endoteliais, os eritrócitos possuem NOS endotelial (eNOS) e induzível (iNOS) e, portanto, são capazes de sintetizar óxido nítrico (NO). O presente estudo testou a capacidade que diferentes concentrações de óleo de peixe tem de ativar a via L-arginina-NO e, em seguida, alterar os níveis de guanosina monofosfato cíclica (GMPc) em eritrócitos de camundongos alimentados com dieta hiperlipídica. Além disso, foram analisados os marcadores de estresse oxidativo nos eritrócitos, objetivando investigar a biodisponibilidade do NO. O transporte de L-arginina, avaliado através da incubação com L-[3H]-arginina, mostrou-se ativado quando da administração de dietas contendo elevadas concentrações de óleo de peixe, em comparação com as dietas contendo baixas concentrações e controle. A atividade da NOS, medida pela conversão de L-[3H]-arginina em L-[3H]-citrulina, e a expressão da eNOS também aumentaram nos animais que se alimentaram com dietas ricas em óleo de peixe. Apesar da ativação da via L-arginina-óxido nítrico observada em nossos experimentos, os níveis de GMPc intraeritrocitário não foram afetados. O dano oxidativo nos eritrócitos aumentou linearmente conforme o óleo de peixe era acrescido na dieta, sem afetar a atividade das enzimas antioxidantes. Além do endotélio, os eritrócitos contribuem para o metabolismo do NO. Desta forma, a ativação da via L-arginina-NO nessas células pode ser benéfica para saúde cardiovascular. Estudos futuros poderão investigar outros marcadores de estresse oxidativo durante o consumo de óleo de peixe para assegurar que o seu uso não resulta em efeitos prejudiciais secundários e para garantir a biodisponibilidade de NO. / The n-3 polyunsaturated fatty acids derived from fish oil are associated with cardiovascular benefits and it has been suggested that the activation of nitric oxide synthase (NOS) would be a potential mechanism responsible for its effects. Beside endothelial cells, red blood cells (RBC) possess endothelial NOS (eNOS) and inducible NOS (iNOS), and thus are capable of synthesizing their own nitric oxide (NO). The present study tested the capacity of different amounts of fish oil to activate L-arginine-NO pathway and therefore alter cyclic guanosine monophosphate (cGMP) levels in RBC from mice fed on a high fat diet. Additionally, the oxidative status in RBC was performed to investigate NO bioavailability. L-arginine transport, assessed by incubation with L-[3H]-arginine, was activated by higher doses of fish oil, compared to control diet and to lowest doses of fish oil. RBC NOS activity, measured by the conversion of L-[3H]-arginine into L-[3H]-citrulline, and eNOS expression were also enhanced by diets rich in fish oil. Despite the L-arginine-NO activation, no effect on intra RBC cGMP basal levels was seen among the groups. Oxidative damage of RBC rises linearly with increasing amounts of fish oil in the diet without affecting the activity of antioxidant enzymes. Besides endothelium, red blood cells also contribute regulating the NO bioactivity. Therefore, the activation of L-arginine-NO pathway in RBC by fish oil would be beneficial in cardiovascular health. Future studies testing other oxidant markers during dietary fish oil supplementation will be necessary to verify that its consumption does not result in detrimental secondary effects and to ensure NO bioavailability.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A modulação do tecido adiposo marrom (TAM) e do tecido adiposo branco (TAB) está associada à prevenção ou redução do ganho de massa corporal. O óleo de peixe possui diversos efeitos benéficos que podem estar relacionados a esses tecidos. Dessa forma, objetivou-se avaliar os efeitos antiobesogênicos de diferentes dietas hiperlipídicas com óleo de peixe na termogênese do TAM e na lipogênese e beta-oxidação do TAB. Para isso, foram utilizados camundongos machos C57BL/6, com três meses de idade, que foram divididos em quatro grupos experimentais: um que recebeu dieta standard-chow (SC, 10% kcal de lipídios) e outros três que receberam dieta hiperlipídica (HL, 50% kcal de lipídios). Obtivemos os grupos HL com banha de porco (HL-B), HL com banha de porco mais óleo de peixe (HL-B+Px) e HL com óleo de peixe (HL-Px). As dietas foram administradas por um período de oito semanas, sendo que a ingestão alimentar foi avaliada diariamente e a massa corporal, semanalmente. Na última semana de experimento, realizou-se a calorimetria indireta e o teste oral de tolerância à glicose. No sacrifício, a glicemia foi aferida, o sangue foi puncionado para obtenção do plasma e o TAM interescapular e o TAB epididimário foram dissecados e armazenados. A leptina, os triglicerídeos e a insulina foram mensurados no plasma. O índice de adiposidade e o HOMA-IR foram calculados. O TAM e o TAB foram avaliados por microscopia confocal e de luz. Realizou-se RT-qPCR e Western blot para avaliação de marcadores termogênicos, da captação e oxidação de ácidos graxos e glicose e de PPAR no TAM, e para a avaliação da lipogênese e beta-oxidação e de PPAR no TAB. Com relação aos resultados, o grupo HL-B apresentou ganho de massa corporal e elevação da adiposidade, associado com hipertrofia dos adipócitos, hiperleptinemia, hipertrigliceridemia, intolerância à glicose e resistência à insulina, reproduzindo um quadro de obesidade e síndrome metabólica. Por outro lado, a ingestão de óleo de peixe nos dois grupos (HL-B+Px e HL-Px) foi capaz de reduzir o ganho de massa corporal e a adiposidade, sem alterar a ingestão alimentar. Essa ingestão também aumentou o gasto energético dos animais, regularizou a leptina e os triglicerídeos plasmáticos, bem como a tolerância à glicose e a resistência à insulina. Esses efeitos foram associados ao aumento de marcadores termogênicos no TAM, bem como da captação e oxidação de ácidos graxos e glicose e da expressão de PPAR nesse tecido. No TAB, houve redução de marcadores da lipogênese e aumento de marcadores da beta-oxidação, juntamente com elevação na expressão de PPAR. Em conclusão, nossos resultados mostram que a ingestão de óleo de peixe tem efeitos antiobesogênicos em camundongos através da modulação benéfica do TAM e do TAB e pode, portanto, representar uma terapia auxiliar alternativa contra a obesidade e suas comorbidades. / Brown adipose tissue (BAT) and white adipose tissue (WAT) modulation is associated with prevention or reduction of body mass gain. Fish oil has several beneficial effects which can be related to these tissues. Thus, we aimed to evaluate the anti-obesity effects of different high-fat diets with fish oil on BAT thermogenesis and WAT lipogenesis and beta-oxidation. For this, we used 3-mo-old C57BL/6 male mice that were divided into four groups: one that received a standard-chow diet (SC, 10% kcal of lipids) and three that received a high-fat diet (HF, 50% kcal of lipids). We obtained the HF with lard group (HF-L), the HF with lard plus fish oil group (HF-L+FO), and the HF with fish oil group (HF-FO). Diets were administrated for eight weeks, and food intake was evaluated daily and the body mass, weekly. At the end of the experiment, we performed indirect calorimetry and an oral glucose tolerance test. At sacrifice, glycemia was assessed, the blood was punctured to obtain plasma and interscapular BAT and epididymal WAT were dissected and stored. Plasmatic leptin, triglycerides and insulin were analyzed. Adiposity index and HOMA-IR were calculated. BAT and WAT were evaluated through confocal and light microscopy. RT-qPCR and Western blot were performed for analyses of thermogenic markers, fatty acids and glucose uptake and oxidation, and PPAR in BAT, and lipogenesis, beta-oxidation and PPAR in WAT. In relation to the results, the HF-L group presented elevated body mass gain and adiposity, associated with adipocyte hypertrophy, hyperleptinemia, hypertriglyceridemia, glucose intolerance and insulin resistance, displaying a condition that simulates obesity and metabolic syndrome. On the contrary, fish oil intake in both groups (HF-L+FO and HF-FO) was able to reduce body mass gain and adiposity, without affecting food intake. It also increased energy expenditure, normalized plasmatic leptin and triglycerides as well as glucose tolerance and insulin resistance. These effects were associated with increases in thermogenic markers, in uptake and oxidation of fatty acids and glucose and in PPAR expression in BAT. In WAT, lipogenesis was reduced and beta-oxidation and PPAR expression were increased. In conclusion, our results demonstrated that fish oil intake has anti-obesity effects in mice through beneficial modulation of BAT and WAT and can, therefore, represent an auxiliary alternative therapy against obesity and its comorbidities.

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Os ácidos graxos poli-insaturados n-3 derivados do óleo de peixe estão associados a benefícios cardiovasculares, que podem ser decorrentes da ativação da óxido nítrico sintase (NOS). Assim como as células endoteliais, os eritrócitos possuem NOS endotelial (eNOS) e induzível (iNOS) e, portanto, são capazes de sintetizar óxido nítrico (NO). O presente estudo testou a capacidade que diferentes concentrações de óleo de peixe tem de ativar a via L-arginina-NO e, em seguida, alterar os níveis de guanosina monofosfato cíclica (GMPc) em eritrócitos de camundongos alimentados com dieta hiperlipídica. Além disso, foram analisados os marcadores de estresse oxidativo nos eritrócitos, objetivando investigar a biodisponibilidade do NO. O transporte de L-arginina, avaliado através da incubação com L-[3H]-arginina, mostrou-se ativado quando da administração de dietas contendo elevadas concentrações de óleo de peixe, em comparação com as dietas contendo baixas concentrações e controle. A atividade da NOS, medida pela conversão de L-[3H]-arginina em L-[3H]-citrulina, e a expressão da eNOS também aumentaram nos animais que se alimentaram com dietas ricas em óleo de peixe. Apesar da ativação da via L-arginina-óxido nítrico observada em nossos experimentos, os níveis de GMPc intraeritrocitário não foram afetados. O dano oxidativo nos eritrócitos aumentou linearmente conforme o óleo de peixe era acrescido na dieta, sem afetar a atividade das enzimas antioxidantes. Além do endotélio, os eritrócitos contribuem para o metabolismo do NO. Desta forma, a ativação da via L-arginina-NO nessas células pode ser benéfica para saúde cardiovascular. Estudos futuros poderão investigar outros marcadores de estresse oxidativo durante o consumo de óleo de peixe para assegurar que o seu uso não resulta em efeitos prejudiciais secundários e para garantir a biodisponibilidade de NO. / The n-3 polyunsaturated fatty acids derived from fish oil are associated with cardiovascular benefits and it has been suggested that the activation of nitric oxide synthase (NOS) would be a potential mechanism responsible for its effects. Beside endothelial cells, red blood cells (RBC) possess endothelial NOS (eNOS) and inducible NOS (iNOS), and thus are capable of synthesizing their own nitric oxide (NO). The present study tested the capacity of different amounts of fish oil to activate L-arginine-NO pathway and therefore alter cyclic guanosine monophosphate (cGMP) levels in RBC from mice fed on a high fat diet. Additionally, the oxidative status in RBC was performed to investigate NO bioavailability. L-arginine transport, assessed by incubation with L-[3H]-arginine, was activated by higher doses of fish oil, compared to control diet and to lowest doses of fish oil. RBC NOS activity, measured by the conversion of L-[3H]-arginine into L-[3H]-citrulline, and eNOS expression were also enhanced by diets rich in fish oil. Despite the L-arginine-NO activation, no effect on intra RBC cGMP basal levels was seen among the groups. Oxidative damage of RBC rises linearly with increasing amounts of fish oil in the diet without affecting the activity of antioxidant enzymes. Besides endothelium, red blood cells also contribute regulating the NO bioactivity. Therefore, the activation of L-arginine-NO pathway in RBC by fish oil would be beneficial in cardiovascular health. Future studies testing other oxidant markers during dietary fish oil supplementation will be necessary to verify that its consumption does not result in detrimental secondary effects and to ensure NO bioavailability.