Léa Silvia Sant'Ana

Influence of the addition of antioxidants in vivo on the fatty acid composition of fish fillets.

In this study, the influence of the addition of antioxidants in vivo on the fatty acid composition of the flesh of a freshwater fish known as “pacu” (Piaractus mesopotamicus) is verified. Four groups (one being the control group) of juvenile “pacu” were cultured on isocaloric and isoproteic diets. The lipid source was soybean oil and diets were added with either 100 ppm of α-tocopheryl acetate, or 100 ppm of BHT or 1.4 g of rosemary extract (Herbalox®)/kg diet. The fatty acid composition of the lipids of the different groups was determined before and after irradiation at 2 and 3 kGy, respectively, for the evaluation of the protective effects of the different antioxidants. Similarly, thiobarbituric acid reactive substances (TBARS) were determined from irradiated and nonirradiated samples. The results showed that the use of antioxidants altered the fatty acid composition of the fillets. TBARS and irradiation confirmed their important role in protecting against lipid oxidation. Among all the antioxidants used, tocopherol was the most efficient, as shown by the highest percentage of polyunsaturated fatty acids (PUFA), by the lowest values of TBARS and by the analyses of the individual fatty acid levels at different irradiation doses. Significant statistical differences were observed only in 17% of the fatty acids in the fillets of the groups.

Influence of AIN-93 diet on mortality and cardiac remodeling after myocardial infarction in rats

BACKGROUND The AIN-93 diet was proposed by the American Institute of Nutrition with the objective of standardising studies in experimental nutrition. Our objective was to analyze the effects of AIN-93 diet after myocardial infarction in rats. METHODS Post weaning, the animals were divided into two groups: control (C, n=62), fed the standard diet of our laboratory (Labina); AIN-93 Group (n=70), fed the AIN-93 diet. Achieving 250 g, the animals were subjected to myocardial infarction. RESULTS Early mortality was increased in AIN-93 animals, associated with lower serum levels of calcium, magnesium, potassium, sodium, and phosphorus. On the other hand, after 90 days, AIN-93 showed smaller normalized left ventricular dimensions. The caloric and carbohydrate intake was smaller, but the fat intake was higher in AIN-93 rats. AIN-93 group also showed increased levels of β-hydroxyacylcoenzyme A dehydrogenase and citrate synthase. In addition, serum levels of insulin and cardiac levels of malondialdehyde, metalloproteinases-2 and -9, and TNF-α and IFN-γ were decreased in the AIN-93 group. CONCLUSION AIN-93 diet increased early mortality, while attenuated the chronic remodeling process after experimental coronary occlusion. Therefore, this diet has biological effects and should be use with attention in this model.

Effect of unsaturated fatty acids on myocardial performance, metabolism and morphology

Diets rich in saturated fatty acids are one of the most important causes of atherosclerosis in men, and have been replaced with diets rich in unsaturated fatty acids (UFA) for the prevention of this disorder. However, the effect of UFA on myocardial performance, metabolism and morphology has not been completely characterized. The objective of the present investigation was to evaluate the effects of a UFA-rich diet on cardiac muscle function, oxidative stress, and morphology. Sixty-day-old male Wistar rats were fed a control (N = 8) or a UFA-rich diet (N = 8) for 60 days. Myocardial performance was studied in isolated papillary muscle by isometric and isotonic contractions under basal conditions after calcium chloride (5.2 mM) and ss-adrenergic stimulation with 1.0 microM isoproterenol. Fragments of the left ventricle free wall were used to study oxidative stress and were analyzed by light microscopy, and the myocardial ultrastructure was examined in left ventricle papillary muscle. After 60 days the UFA-rich diet did not change myocardial function. However, it caused high lipid hydroperoxide (176 +/- 5 vs 158 +/- 5, P < 0.0005) and low catalase (7 +/- 1 vs 9 +/- 1, P < 0.005) and superoxide-dismutase (18 +/- 2 vs 27 +/- 5, P < 0.005) levels, and discrete morphological changes in UFA-rich diet hearts such as lipid deposits and mitochondrial membrane alterations compared to control rats. These data show that a UFA-rich diet caused myocardial oxidative stress and mild structural alterations, but did not change mechanical function.

Chemical composition and fatty acid contents in farmed freshwater prawns

The objective of this work was to evaluate the chemical composition and fatty acid contents of Amazonian and giant river prawns. After four-month farming, with the same diet for both species, palmitic and stearic acids were the main saturated fatty acids. Oleic acid was the main monounsatured fatty acid, and the eicosapentaenoic and docosahexaenoic acids were the most abundant polyunsaturated acids. Amazonian prawn has higher levels of protein and polyunsaturated fatty acids than those of the giant river prawn, which shows its potential for aquaculture.

Influências de dietas ricas em ácidos graxos saturados e insaturados sobre o miocárdio de ratos

OBJETIVOS: O estudo avaliou a influencia de dietas ricas em acidos graxos saturados (AGS) e acidos graxos insaturados (AGI) sobre a funcao mecânica, a morfologia e o estresse oxidativo do miocardio de ratos. METODOS: Ratos Wistar com 60 dias de idade foram alimentados com dieta padrao (n = 8) ou dietas ricas em AGS (n = 8) ou AGI (n = 8) durante 60 dias. A funcao mecânica foi avaliada em musculo papilar isolado do ventriculo esquerdo (VE) por meio de contracoes isometrica e isotonica, em condicao basal (1,25 mM de calcio), apos elevacao da concentracao extracelular de calcio para 5,2 mM e estimulacao b-adrenergica com isoproterenol 1,0 µM. Fragmentos do VE foram usados para estudo de estresse oxidativo e microscopias optica e eletronica. RESULTADOS: As dietas suplementadas com AGS e AGI nao alteraram a funcao mecânica do musculo cardiaco. Entretanto, ambas provocaram estresse oxidativo, com aumento do hidroperoxido de lipidio e reducao da concentracao de superoxido dismutase. A dieta AGI diminuiu a expressao da catalase e a AGS reduziu a quantidade de glutationa peroxidase miocardica. Ambas as dietas promoveram discretas alteracoes morfologicas visualizadas ultra-estruturalmente, como depositos lipidicos e lesoes das membranas celulares. CONCLUSAO: Os resultados sugerem que dietas enriquecidas com AGS e AGI nao acarretam alteracao da funcao mecânica do musculo cardiaco isolado, mas causam discretas lesoes estruturais e estresse oxidativo no miocardio.