High-linoleate and high-alpha-linolenate diets affect learning ability and natural behavior in SAMR1 mice.
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Semipurified diets incorporating either perilla oil [high in alpha-linolenate, 18:3(n-3)] or safflower oil [high in linoleate, 18:2(n-6)] were fed to senescence-resistant SAMR1 mouse dams and their pups. Male offspring at 15 mo were examined using behavioral tests. In the open field test, locomotor activity during a 5-min period was significantly higher in the safflower oil group than in the perilla oil group. Observations of the circadian rhythm (48 h) of spontaneous motor activity indicated that the safflower oil group was more active than the perilla oil group during the first and second dark periods. The total number of responses to positive and negative stimuli was higher in the safflower oil group than in the perilla oil group in the light and dark discrimination learning test, but the correct response ratio was lower in the safflower oil group. The difference in the (n-6)/(n-3) ratios of the diets reflected the proportions of (n-6) polyunsaturated fatty acids, rather than those of (n-3) polyunsaturated fatty acids in the brain total fatty acids, and in the proportions of (n-6) and (n-3) polyunsaturated fatty acids in the total polyunsaturated fatty acids of the brain phospholipids. These results suggest that in SAMR1 mice, the dietary alpha-linolenate/linoleate balance affects the (n-6)/(n-3) ratio of brain phospholipids, and this may modify emotional reactivity and learning ability. (+info)
Effect of dietary alpha-linolenic acid on thrombotic risk factors in vegetarian men.
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BACKGROUND: Vegetarians have lower platelet and plasma concentrations of n-3 polyunsaturated fatty acids (PUFAs) than do omnivores. We recently showed that male vegetarians have higher platelet aggregability than do omnivores. OBJECTIVE: We investigated whether male vegetarians (n = 17) who consumed an increased amount of dietary alpha-linolenic acid (ALA) showed any changes in their tissue profile of PUFAs, plasma thromboxane concentrations, platelet aggregability, or hemostatic factors. DESIGN: During the study, all subjects maintained their habitual vegetarian diets except that a proportion of dietary fat was replaced with vegetable oils and margarines that were provided. Initially, all subjects consumed a low-ALA diet (containing safflower oil and safflower oil-based margarine) for 14 d; they then consumed either a moderate-ALA diet (containing canola oil and canola oil-based margarine) or a high-ALA diet (containing linseed oil and linseed oil-based margarine) for 28 d. Blood samples were collected at day 0 (baseline), day 14, and day 42. RESULTS: Eicosapentaenoic acid, docosapentaenoic acid, total n-3 PUFAs, and the ratio of n-3 to n-6 PUFAs were significantly increased (P < 0.05), whereas the ratio of arachidonic acid to eicosapentaenoic acid was decreased (P < 0.05), in platelet phospholipids, plasma phospholipids, and triacylglycerols after either the moderate-ALA or high-ALA diet compared with the low-ALA diet. No significant differences were observed in thrombotic risk factors. CONCLUSION: ALA from vegetable oils (canola and linseed) has a beneficial effect on n-3 PUFA concentrations of platelet phospholipids and plasma lipids in vegetarian males. (+info)
Dietary intake of alpha-linolenic acid and risk of fatal ischemic heart disease among women.
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BACKGROUND: Experimental studies in laboratory animals and humans suggest that alpha-linolenic acid (18:3n-3) may reduce the risk of arrhythmia. OBJECTIVE: The objective was to examine the association between dietary intake of alpha-linolenic acid and risk of fatal ischemic heart disease (IHD). DESIGN: This was a prospective cohort study. The intake of alpha-linolenic acid was derived from a 116-item food-frequency questionnaire completed in 1984 by 76283 women without previously diagnosed cancer or cardiovascular disease. RESULTS: During 10 y of follow-up, we documented 232 cases of fatal IHD and 597 cases of nonfatal myocardial infarction. After adjustment for age, standard coronary risk factors, and dietary intake of linoleic acid and other nutrients, a higher intake of alpha-linolenic acid was associated with a lower relative risk (RR) of fatal IHD; the RRs from the lowest to highest quintiles were 1.0, 0.99, 0.90, 0.67, and 0.55 (95% CI: 0.32, 0.94; P for trend = 0.01). For nonfatal myocardial infarction there was only a modest, nonsignificant trend toward a reduced risk when extreme quintiles were compared (RR: 0.85; 95% CI: 0.61, 1.19; P for trend = 0.50). A higher intake of oil and vinegar salad dressing, an important source of alpha-linolenic acid, was associated with reduced risk of fatal IHD when women who consumed this food > or =5-6 times/wk were compared with those who rarely consumed this food (RR: 0.46; 95% CI: 0.27, 0.76; P for trend = 0.001). CONCLUSIONS: This study supports the hypothesis that a higher intake of alpha-linolenic acid is protective against fatal IHD. Higher consumption of foods such as oil-based salad dressing that provide polyunsaturated fats, including alpha-linolenic acid, may reduce the risk of fatal IHD. (+info)
Prevention of sudden cardiac death by dietary pure omega-3 polyunsaturated fatty acids in dogs.
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BACKGROUND: Rat diets high in fish oil have been shown to be protective against ischemia-induced fatal ventricular arrhythmias. Increasing evidence suggests that this may also apply to humans. To confirm the evidence in animals, we tested a concentrate of the free fish-oil fatty acids and found them to be antiarrhythmic. In this study, we tested the pure free fatty acids of the 2 major dietary omega-3 polyunsaturated fatty acids in fish oil: cis-5,8,11,14, 17-eicosapentaenoic acid (C20:5omega-3) and cis-4,7,10,13,16, 19-docosahexaenoic acid (C22:6omega-3), and the parent omega-3 fatty acid in some vegetable oils, cis-9,12,15-alpha-linolenic acid (C18:3omega-3), administered intravenously on albumin or a phospholipid emulsion. METHODS AND RESULTS: The tests were performed in a dog model of cardiac sudden death. Dogs were prepared with a large anterior wall myocardial infarction produced surgically and an inflatable cuff placed around the left circumflex coronary artery. With the dogs running on a treadmill 1 month after the surgery, occlusion of the left circumflex artery regularly produced ventricular fibrillation in the control tests done 1 week before and after the test, with the omega-3 fatty acids administered intravenously as their pure free fatty acid. With infusion of the eicosapentaenoic acid, 5 of 7 dogs were protected from fatal ventricular arrhythmias (P<0.02). With docosahexaenoic acid, 6 of 8 dogs were protected, and with alpha-linolenic acid, 6 of 8 dogs were also protected (P<0.004 for each). The before and after control studies performed on the same animal all resulted in fatal ventricular arrhythmias, from which they were defibrillated. CONCLUSIONS: These results indicate that purified omega-3 fatty acids can prevent ischemia-induced ventricular fibrillation in this dog model of sudden cardiac death. (+info)
Antisense-mediated depletion of potato leaf omega3 fatty acid desaturase lowers linolenic acid content and reduces gene activation in response to wounding.
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Fatty acid omega3 desaturases act on membrane lipids to catalyse the formation of trienoic fatty acids, the most abundant in plant tissues being alpha-linolenic acid. This fatty acid is a precursor of jasmonic acid, a plant growth regulator involved in the control of wound-induced gene activation in plants and in the induction of tuberization in potato. We isolated a potato omega3 desaturase cDNA, possibly encoding a plastidial isoform, and used it to investigate its expression pattern throughout plant development and in response to wounding. Plastidial omega3 desaturase gene transcripts accumulate rapidly upon wounding, preceding the jasmonate-dependent induction of the wound-responsive proteinase inhibitor II gene. We generated transgenic potato plants constitutively expressing an antisense RNA to this plastidial omega3 desaturase. Selected transgenic lines in which the cognate omega3 desaturase mRNA is largely depleted show a marked reduction, of up to 60%, in trienoic acids in leaves and tubers. In these lines, a corresponding reduction in jasmonate content and proteinase inhibitor II expression is observed upon wounding. Our results indicate that a reduction in omega3 desaturase mRNA levels compromises the wound-induced activation of proteinase inhibitor II, suggesting that wound-induced synthesis of linolenic acid is required for jasmonic acid production. The antisense-mediated depletion of fatty acid omega3 desaturases is a viable alternative for reducing trienoic fatty acid content in plant species in which a mutant screening approach is not applicable. (+info)
Differences in essential fatty acid requirements by enteral and parenteral routes of administration in patients with fat malabsorption.
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BACKGROUND: Essential fatty acid (EFA) requirements of patients receiving home parenteral nutrition (HPN) are uncertain. OBJECTIVE: The objective was to evaluate the influence of the route of administration (enteral compared with parenteral) on plasma phospholipid EFA concentrations. DESIGN: Intestinal absorption, parenteral supplement of EFAs, and plasma phospholipid EFA concentrations were investigated in balance studies in 4 groups (A, B, C, and D) of 10 patients with short-bowel syndrome and a fecal loss of >2000 kJ/d. Groups A (fat malabsorption <50%) and B (fat malabsorption >50%) did not receive HPN, whereas group C received HPN containing lipids (7.5 and 1.2 g/d linoleic and linolenic acids, respectively) and group D received fat-free HPN. RESULTS: Intestinal absorption of linoleic and linolenic acids was 8.9 and 1.3 g/d and 2. 6 and 0.4 g/d in groups A and B, respectively, whereas EFA absorption was negligible in groups C and D. Thus, intestinal absorption of EFAs in group A corresponded to parenteral EFA supplements in group C, whereas group D was almost totally deprived of EFAs. The median plasma phospholipid concentration of linoleic acid decreased by 21.9%, >16.3%, >13.8%, 11.0%, and >7.7% and linolenic acid by 0.3%, 0.2%, 0.2%, >0.2%, and 0.1%, respectively, in 10 healthy control subjects and groups A, B, C, and D (P < 0.001). CONCLUSIONS: Intestinally absorbed EFAs maintained plasma EFA status better than did an equal quantity of parenterally supplied EFAs. Intravenous requirements of EFAs in patients with negligible absorption of EFAs are probably higher than the amounts recommended to patients with preserved intestinal absorption of EFAs. (+info)
Salicylhydroxamic acid inhibits delta6 desaturation in the microalga Porphyridium cruentum.
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Treatment of the microalga Porphyridium cruentum with salicylhydroxamic acid (SHAM) inhibited growth and affected fatty acid composition. At a relatively low concentration (40 microM) SHAM predominantly inhibits Delta6 desaturation. The effect of the inhibitor was most intense in phosphatidylcholine (PC) and phosphatidylethanolamine, in which the proportions of the downstream products of the Delta6 desaturase were reduced, whereas that of the substrate, 18:2, increased. As a result of the availability of 18:2, 18:3omega3, which under normal conditions is not observed, appeared predominantly in chloroplastic lipids. Pulse labeling with linoleic acid has shown that SHAM inhibits Delta6 desaturation almost immediately, suggesting an apparent inhibition of the activity of the desaturase, rather than its synthesis or that of its cofactors. Furthermore, the addition of gamma-linolenic acid to SHAM-inhibited cultures relieved the inhibition. Following exposure to the inhibitor, 18:3omega3 appeared first in chloroplastic glycolipids and only later in PC, indicating that the former are the substrates for the first dedicated step of the proposed omega3 pathway in this alga. (+info)
Exposure to flaxseed or its lignan component during different developmental stages influences rat mammary gland structures.
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Reduction of the highly proliferative terminal end bud (TEB) structures in the developing mammary gland by differentiation to alveolar buds (ABs) and lobules has been suggested to be protective against mammary cancer. Flaxseed is high in alpha-linolenic acid (ALA) and secoisolariciresinol diglycoside (SDG). SDG is the precursor of mammalian lignans, which can affect mammary gland structures. Thus, the objective of this study was to determine the effect of lifetime, gestation and lactation or after-weaning exposure to 5 or 10% flaxseed or SDG and flaxseed oil components on the mammary gland structures of virgin female rat offspring at post-natal day 50. Lifetime or gestation and lactation exposure to flaxseed altered mammary gland structure development, whereas exposure to flaxseed after weaning had no effect. Lifetime or gestation and lactation exposure to 5% flaxseed caused endocrine changes, as suggested by delayed puberty onset and reduced number of estrous cycles. These changes reduced exposure to endogenous estrogens, leading to atrophy of mammary TEB structures. SDG, but not flaxseed oil, at the level found in 5% flaxseed produced similar effects as 5% flaxseed. This suggested that the lignans were the component in flaxseed responsible for the observed effects. Lifetime or gestation and lactation exposure to 10% flaxseed also caused endocrine changes, as suggested by early puberty onset and lengthened cycles due to prolonged estrus. This increased exposure to endogenous estrogens and stimulated mammary gland differentiation, as indicated by fewer TEBs and more ABs. Thus, lifetime or gestation and lactation exposure to 5 or 10% flaxseed induced structural changes in the mammary gland that may potentially reduce mammary cancer risk. (+info)