Mariano Mañas

Tissue Specific Interactions of Exercise, Dietary Fatty Acids, and Vitamin E in Lipid Peroxidation

Both physical exercise and ingestion of polyunsaturated fatty acids that play an essential role in free radical-mediated damages cause lipid peroxidation. The intake of specific fatty acids can modulate the membrane susceptibility to lipid peroxidation. Data confirmed that liver, skeletal muscle, and heart have different capabilities to adapt their membrane composition to dietary fatty acids, the heart being the most resistant to changes. Such specificity affects membrane hydroperoxide levels that depend on the type of dietary fats and the rate of fatty acid incorporation into the membrane. Sedentary rats fed a monounsaturated fatty acid-rich diet (virgin olive oil) showed a higher protection of their mitochondrial membranes against peroxidation than sedentary rats fed a polyunsaturated fatty acid-rich diet (sunflower oil). Rats subjected to training showed higher hydroperoxide contents than sedentary animals, and exhaustive effort enhanced the aforementioned results as well as in vitro peroxidation with a free radical inducer. This study suggests that peroxide levels first depend on tissue, then on diet and lastly on exercise, both in liver and muscle but not in heart. Finally, it appears that alpha-tocopherol is a less relevant protective agent against lipid peroxidation than monounsaturated fatty acids.

The intake of fried virgin olive or sunflower oils differentially induces oxidative stress in rat liver microsomes.

The effects of non-fried and fried virgin olive and sunflower oils on rat liver microsomal compositional features have been investigated. In addition, plasma antioxidants (alpha-tocopherol and ubiquinone 9) were investigated as well as the possible oxidative modifications suffered by virgin olive and sunflower oils during the frying process. The frying process decreased the content of alpha-tocopherol and phenolics in the oils and increased total polar materials. Sunflower oil was affected to a greater extent than olive oil. In rats, the intake of fried oil led to higher levels of lipid peroxidation and a lower concentration of plasma antioxidants. Microsomal fatty acid and antioxidant profiles were also altered. It seems that a strong relationship exists between the loss of antioxidants and the production of toxic compounds in the oils after frying and the extent of the peroxidative events in microsomes, which were also different depending on the fat source. The highly unsaturated sunflower oil was less resistant to the oxidative stress produced by frying and led to a higher degree of lipid peroxidation in liver microsomes in vivo than virgin olive oil.

Physical exercise affects the lipid profile of mitochondrial membranes in rats fed with virgin olive oil or sunflower oil.

The effects of physical exercise on the lipid profile in mitochondrial membranes of liver and skeletal muscle were examined in rats fed with virgin olive oil or sunflower oil. Thirty male Wistar rats, 21 d old, were randomly assigned to four groups according to fat ingestion and physical activity over an 8-week period. For each type of oil, one group acted as a control group while rats from the other were trained to run for 40 min daily on a horizontal treadmill, at a speed of 35 m/min. The results show that diet affected the fatty acid profile of the mitochondrial membranes from skeletal muscle and liver. Physical exercise also modified the fatty acid profile of the mitochondrial membranes. Total monounsaturated fatty acids decreased (P < 0.001) in liver mitochondria of exercised animals. Total polyunsaturated fatty acids in mitochondrial membranes of liver increased (P < 0.005) after exercise but those in mitochondrial membranes of skeletal muscle decreased (P < 0.05). These changes due to the exercise may arise via several mechanisms, e.g. fluidity regulation; changes in the eicosanoid metabolism; differences in the availability or oxidation rate of the different fatty acids.

Feeding Fried Oil Changes Antioxidant and Fatty Acid Pattern of Rat and Affects Rat Liver Mitochondrial Respiratory Chain Components

Fat frying is a popular food preparation method but several components like antioxidant vitamins could be lost due to oxidation and some others with toxic effects could appear. Because of such large consumption of frying oils, the effect of high temperatures on the oils is of major concern both for product quality and nutrition, taking into account that dietary fat source deeply influences several biochemical parameters, especially of mitochondrial membranes. Virgin olive oil possesses specific features for modulating the damages occurred by endogenous and exogenous oxidative stress being particularly rich in antioxidant molecules. We evaluated the extent of modifications suffered by virgin olive oil following a short-time deep fat frying procedure: vitamin E and phenolic compound as well as total antioxidant capacity (measured by ESR) decreased, while polar compounds increased. The intake of such an altered oil mainly affected the hydroperoxide and TBARS contents of mitochondrial membranes which were enhanced after the dietary treatments. Also, several mitochondrial respiratory chain components (Coenzyme Q, cytochrome b, c + c1, and a + a3) were affected.

Dietary fat type and regular exercise affect mitochondrial composition and function depending on specific tissue in the rat.

Physical exercise and fatty acids have been studied in relation to mitochondrial composition and function in rat liver, heart, and skeletal muscle. Male rats were divided into two groups according to dietary fat type (virgin olive and sunflower oils). One-half of the animals from each group were subjected to a submaximal exercise for 8 weeks; the other half acted as sedentary controls. Coenzyme Q, cytochromes b, c + c1, a + a3 concentrations, and the activity of cytochrome c oxidase were determined. Regular exercise increased (P < 0.05) the concentration of the above-mentioned elements and the activity of the cytochrome c oxidase by roughly 50% in liver and skeletal muscle. In contrast, physical exercise decreased (P < 0.05) cytochrome c oxidase activity in the heart (in μmol/min/g, from 8.4 ± 0.1 to 4.9 ± 0.1 in virgin olive oil group and from 9.7 ± 0.1 to 6.7 ± 0.2 in sunflower oil animals). Dietary fat type raised the levels of coenzyme Q, cytochromes, and cytochrome c oxidase activity in skeletal muscle (P < 0.05) among the rats fed sunflower oil. In conclusion, dietary fat type, regular exercise, and the specific tissue modulate composition and function of rat mitochondria.

Oxidative stress induced by exercise and dietary fat modulates the coenzyme Q and vitamin A balance between plasma and mitochondria.

Physical exercise induces oxidative stress. Dietary fat modulates lipid composition of plasma and fatty acid profile of mitochondrial membranes. Over 8 wk, two groups of rats were fed virgin olive oil or sunflower oil as the only fat sources. Both groups were divided into 4 subgroups according to exercise: one of sedentary rats and the other three of rats subjected to different exercises on a treadmill. There was a lower concentration of vitamin A and coenzyme Q in the plasma of animals subjected to exercise compared to the sedentary animals. The concentrations of these molecules in liver and skeletal muscle mitochondria of animals exercised until exhaustion were higher than in sedentary animals. This can suggest the existence of a balance between plasma and mitochondrial membrane for these antioxidants as a response to an oxidative attack.

Dietary Fat (Virgin Olive Oil or Sunflower Oil) and Physical Training Interactions on Blood Lipids in the Rat

OBJECTIVE We investigated whether the intake of virgin olive oil or sunflower oil and performance of physical exercise (at different states) affect plasma levels of triacylglycerols, total cholesterol, and fatty acid profile in rats. METHODS The study was carried out with six groups of male rats subjected for 8 wk to a diet based on virgin olive oil (three groups) or sunflower oil (three groups) as dietary fat. One group for each diet acted as sedentary control; the other two groups ran in a treadmill for 8 wk at 65% of the maximum oxygen consumption. One group for each diet was killed 24 h after the last bout of exercise and the other was killed immediately after the exercise performance. Triacylglycerols, total cholesterol, and fatty acid profile were analyzed in plasma. Analysis of variance was used to test differences among groups. RESULTS Animals fed on virgin olive oil had lower triacylglycerol and cholesterol values. Physical exercise reduced these parameters with both dietary treatments. Fatty acid profile showed higher monounsaturated fatty acid proportion in virgin olive fed oil animals and a higher omega-6 polyunsaturated fatty acid proportion in sunflower oil fed animals. Physical exercise reduced the levels of monounsaturated fatty acids with both diets and increased the proportions of omega-3 polyunsaturated fatty acids. CONCLUSIONS Results from the present study supported the idea that physical exercise and the intake of virgin olive oil are very good ways of reducing plasma triacylglycerols and cholesterol, which is desirable in many pathologic situations. Concerning findings on fatty acid profile, we had results similar to those of other investigators regarding the effect of different sources of dietary fat on plasma. The most interesting results came from the effect of physical exercise, with significant increases in the levels of omega-3 polyunsaturated fatty acids, which may contribute to the antithrombotic state and lower production of proinflammatory prostanoids attributed to physical exercise.

Influence of type of dietary fat (olive and sunflower oil) upon gastric acid secretion and release of gastrin, somatostatin, and peptide YY in man.

The effects of adaptation to two diets differingin the type of dietary fat on the gastric acid secretoryresponse to food and on the circulating levels ofgastrin, somatostatin and peptide YY (PYY) were examined in humans. The study involved 18cholecystectomized subjects previously submitted to a30-day adaptation period to diets containing olive(group O) or sunflower oil (group S) as the fat source. During the experiments, physiologicalstimulation was achieved by ingestion of 200 ml of oleicacid- (group O) or linoleic acid-enriched (group S)liquid mixed meals. These resulted in an immediate rise in gastric pH. In group S, the return to thepremeal value was completed within 60 min, and a furtherdecline to values significantly lower than the basalones was observed at the end of the study period. In contrast, ingestion of the meal containingolive oil attenuated and prolonged the pH decrease afterthe meal, this being associated with the suppression ofpostprandial gastrin response. Food ingestion induced no significant changes in plasmasomatostatin concentration in either group, and nosignificant differences were revealed between themduring the basal or postprandial situations. Plasma PYYlevels were consistently higher in group O throughoutthe entire study period, although significance wasreached only at resting. In conclusion, our results showthat a 30-day adaptation period to diets containing olive oil as the main source of dietary fatresults, compared with those containing sunflower oil,in an attenuated gastric secretory function in responseto a liquid meal in humans. The effects of olive oil were associated with a suppression of serumgastrin and higher levels of PYY.

Peroxidative extent and Coenzyme Q levels in the rat: Influence of physical training and dietary fats

Sport practice is widely recognized as capable of producing peroxidative damages, even of severe intensity. Dietary manipulations can also modify membrane susceptibility to peroxidation. In previous experiments we found that, while dietary virgin olive oil successfully protects mitochondrial and microsomal membranes from endogenous, xenobiotics-induced peroxidation, dietary polyunsaturated oils lead to increased peroxidative levels. In the latter conditions, cell machinery tries to counteract the structural and functional changes which have occurred, by modulating enzyme activities and concentrations, by increasing biosynthesis of coenzyme Q and by mobilizing cholesterol. In the present study we hypothesized that combining these two aspects could give useful information on the membrane response to peroxidation phenomena that daily occur throughout the lifespan. Rats fed different dietary oils as only fat source underwent a carefully designed training program and were killed at different times following acute or chronic exercise. Results show that peroxidation related to chronic training and to an acute bout of exercise sum up with peroxidative effects induced by dietary factors. The above mentioned phenomena occurred simultaneously with increased tissue levels of coenzyme Q, possibly triggered within a physiological reactive antioxidant strategy.

Long-term adaptation of pancreatic response by dogs to dietary fats of different degrees of saturation: Olive and sunflower oil

Mongrel dogs were fed, from weaning to 9 months of age, on one of two diets that differed only in the type of fat content (virgin olive oil or sunflower oil) to compare the composition of exocrine pancreatic secretion in the basal period and in response to food. In resting pancreatic flow, electrolytes and the specific activities of amylase, lipase and chymotrypsin were similar in both experimental groups. However, lipase and amylase outputs, and amylase and protein concentrations were significantly higher in the group fed on the diet rich in sunflower oil. Food intake was not followed by any change in flow-rate or electrolyte or protein content in the group given the diet rich in olive oil. Amylase activity and output were also lower in this group, as was lipase output, whereas activity and specific activity of chymotrypsin were lower in dogs fed on the diet containing sunflower oil. The differences traceable to the composition of the two types of dietary fat supplied may be related to the balance between factors that stimulate and inhibit pancreatic secretion.