Diet (n-3) polyunsaturated fatty acid content and parity interact to alter maternal rat brain phospholipid fatty acid composition

Low tissue levels of (n-3) polyunsaturated fatty acids (PUFAs), particularly docosahexaenoic acid [DHA, 22:6(n-3)], are implicated in postpartum depression. The effects of 1-4 sequential reproductive cycles on maternal brain phospholipid fatty acid composition were determined in female rats fed diets containing alpha-linolenic acid (ALA), containing ALA and pre-formed DHA (ALA+DHA), or lacking ALA (low-ALA). Virgin females, fed the diets for commensurate durations served as a control for reproduction. Whole-brain total phospholipid composition was determined at weaning by TLC/GC. A single reproductive cycle on the low-ALA diet decreased brain DHA content by 18% compared to ALA primiparas (P < 0.05), accompanied by incorporation of docosapentaenoic acid ((n-6) DPA, 22:5(n-6)) to 280% of ALA primiparas (P < 0.05). DHA was not further decreased after subsequent cycles; however, there was an additional increase in (n-6) DPA after the second cycle (P < 0.05). Brain DHA of virgin females fed the low-ALA diet for 27 wk decreased 15% (P < 0.05), but was accompanied by a more modest increase in (n-6) DPA than in parous low-ALA dams (P < 0.05). Virgin females and parous dams fed the diet containing ALA+DHA exhibited only minor changes in brain fatty acid composition. These observations demonstrate that brain DHA content of adult animals is vulnerable to depletion under dietary conditions that supply inadequate (n-3) PUFAs, that this effect is augmented by the physiological demands of pregnancy and lactation, and that maternal diet and parity interact to affect maternal brain PUFA status.     

Specific brain regions of female rats are differentially depleted of docosahexaenoic acid by reproductive activity and an (n-3) fatty acid-deficient diet

Low tissue levels of (n-3) PUFA, particularly docosahexaenoic acid [DHA, 22:6(n-3)], are implicated in postpartum depression. Brain DHA content is depleted in female rats undergoing pregnancy and lactation when the diet supplies inadequate (n-3) PUFA. In this study, the effects of DHA depletion as a result of reproductive activity and an (n-3) PUFA-deficient diet were examined in 8 specific brain regions of female rats after undergoing 2 sequential reproductive cycles. Virgin females, fed the alpha-linolenic acid (ALA)-containing or deficient (low-ALA) diets for a commensurate duration (13 wk) served as a control for reproduction. Total phospholipid composition of each brain region was determined at weaning (postnatal d 21) by TLC/GC. The regional PUFA composition of ALA virgins was similar to that previously measured in male rats. All brain regions examined were affected by reproductive activity and/or the low-ALA diet; however, the magnitude of the loss of DHA and compensatory incorporation of docosapentaenoic acid [(n-6) DPA, 22:5(n-6)] varied among brain regions. In low-ALA parous dams, frontal cortex (77% of ALA virgin) and temporal lobe (83% of ALA virgin), regions involved in cognition and affect, were among those exhibiting the greatest depletion of DHA. Caudate-putamen also exhibited significant depletion of DHA (82% of ALA virgin), whereas only (n-6) DPA levels were altered in ventral striatum, hypothalamus, hippocampus, and cerebellum. This pattern of changes in regional DHA and (n-6) DPA content suggests that specific neuronal systems may be differentially affected by depletion of brain DHA in the postpartum organism.     

不同年龄阶段小鼠脑聚集二十二碳六烯酸及脂肪酸去饱和酶的变化

【目的】 探讨生命早期不同年龄阶段脑摄取、聚集二十二碳六烯酸(DHA)(C22:6n-3)及相关去饱和酶的变化。 【方法】 使用6~8周龄清洁级C57BL/6J雌性小鼠,分别给予n-3 多不饱和脂肪酸(n-3 PUFAs)缺乏饲料和含n-3 PUFAs饲料喂养6周,然后雌雄合笼交配繁殖,新生仔鼠分别于生后7、21 d和42 d时取血、脑和肝脏。采用甲酯化-气相色谱分析对血浆、脑和肝脏中脂肪酸谱进行分析;采用荧光定量PCR方法对脑和肝脏中脂肪酸去饱和酶1(FADS1)和脂肪酸去饱和酶2(FADS2)基因mRNA表达进行检测。 【结果】 对不同年龄小鼠组织脂肪酸的比较发现,脑中DHA和总n-3 PUFAs含量在两种不同饲料组均随年龄增加而升高;而肝中的含量则随年龄增加而降低。与n-3 PUFAs缺乏组相比,饲料中添加n-3 PUFAs可使仔鼠生后7、21 d和42 d时脑和肝脏中DHA和总n-3 PUFAs含量均显著升高;升高的程度在脑组织中随年龄增加而降低,而在肝脏组织中则不随年龄变化。对不同年龄段FADS表达的比较发现,FADS1和FADS2 mRNA在脑组织中的表达量于42 d时显著高于7 d和21 d,而在肝组织中的表达量于各年龄段之间无显著性差异。与n-3 PUFAs缺乏组相比,饲料中添加n-3 PUFAs可使仔鼠生后7 d和21 d时脑组织FADS1和FADS2表达水平显著降低,而42 d时的表达无变化;肝组织中这两种酶mRNA水平在7 d和21 d时无变化,42 d时FADS1显著降低。 【结论】 发育期脑对DHA的聚集需求随着年龄增大而逐渐减少;FADS在脑中的表达水平随年龄增大而升高。同时,饲料n-3 PUFAs缺乏状态对脑聚集DHA以及FADS的影响在年龄小时更明显。     

Diet (n-3) polyunsaturated fatty acid content and parity affect liver and erythrocyte phospholipid fatty acid composition in female rats

The fatty acid composition of membrane phospholipids affects the physicochemical properties of the membrane and thus influences cell function. In this study, the effects of 1-4 sequential pregnancies on the phospholipid fatty acid compositions of the maternal liver and erythrocytes were determined in female rats fed diets containing alpha-linolenic acid (ALA), ALA and preformed docosahexaenoic acid (DHA; ALA+DHA), or minimal ALA (low ALA). Virgin females, fed the diets for commensurate durations, served as a control for reproduction. Liver and erythrocyte total phospholipid compositions were determined at weaning by TLC/GC. In both tissues, significant main effects of diet and reproductive status were detected for many fatty acids, but a significant interaction of diet, reproductive status, and duration of treatment (no. of reproductive cycles or equivalent time period for virgins) was detected only for DHA, 22:6(n-3). Primiparous dams fed the ALA and low ALA diet had decreased liver DHA content of 31% and 74%, respectively, compared with virgin females fed the ALA diet. Liver DHA did not decrease further after additional reproductive cycles. Liver DHA content was unchanged in parous dams fed the ALA+DHA diet, but virgin females fed this diet exhibited a 50% increase in liver DHA after 13 wk of treatment. Changes in erythrocyte DHA were of similar magnitude and time course to those observed in liver, suggesting that this tissue may serve as a marker for liver DHA status.     

Docosahexaenoic acid supplementation from mid-pregnancy to parturition influenced breast milk fatty acid concentrations at 1 month postpartum in Mexican women

(n-3) PUFA, including DHA, are essential for neural development and accumulate extensively in the fetal and infant brain. (n-3) PUFA concentrations in breast milk, which are largely dependent on maternal diet and tissue stores, are correlated with infant PUFA status. We investigated the effect of prenatal DHA supplementation on PUFA concentrations in breast milk at 1 mo postpartum. In a double-blind, randomized, controlled trial conducted in Mexico, pregnant women were supplemented daily with 400 mg DHA or placebo from 18-22 wk gestation to parturition. Fatty acid concentrations in breast milk obtained from 174 women at 1 mo postpartum were determined using GLC and were expressed as % by weight of total detected fatty acids. Breast milk DHA concentrations in the DHA and placebo groups were (mean ± SD) 0.20 ± 0.06 and 0.17 ± 0.07 (P < 0.01), respectively, and those of α-linolenic acid (ALA) were 1.38 ± 0.47 and 1.24 ± 0.46 (P = 0.01), respectively. Concentrations of EPA and arachidonic acid did not differ between groups (P > 0.05). Maternal plasma DHA concentrations at 1 mo postpartum correlated positively with breast milk DHA at 1 mo postpartum in both the placebo and DHA groups (r = 0.4; P < 0.01 for both treatment groups). Prenatal DHA supplementation from 18-22 wk gestation to parturition increased concentrations of DHA and ALA in breast milk at 1 mo postpartum, providing a mechanism through which breast-fed infants could benefit.     

Long-Term Effect of Docosahexaenoic Acid Feeding on Lipid Composition and Brain Fatty Acid-Binding Protein Expression in Rats

Arachidonic (AA) and docosahexaenoic acid (DHA) brain accretion is essential for brain development. The impact of DHA-rich maternal diets on offspring brain fatty acid composition has previously been studied up to the weanling stage; however, there has been no follow-up at later stages. Here, we examine the impact of DHA-rich maternal and weaning diets on brain fatty acid composition at weaning and three weeks post-weaning. We report that DHA supplementation during lactation maintains high DHA levels in the brains of pups even when they are fed a DHA-deficient diet for three weeks after weaning. We show that boosting dietary DHA levels for three weeks after weaning compensates for a maternal DHA-deficient diet during lactation. Finally, our data indicate that brain fatty acid binding protein (FABP7), a marker of neural stem cells, is down-regulated in the brains of six-week pups with a high DHA:AA ratio. We propose that elevated levels of DHA in developing brain accelerate brain maturation relative to DHA-deficient brains.     

High α-linolenic acid and fish oil ingestion promotes ovulation to the same extent in rats

Prostaglandins (PG) have a regulatory influence on ovulation. α-Linolenic acid (ALA) vs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) differently influence PG biosynthesis. Whereas high EPA/DHA reduces PGE₂, enhancing ovulation, we hypothesized that ALA would not affect ovulation. Our objective was to determine the effect of low and high ALA intake vs EPA/DHA on ovarian phospholipids, ovulation, and PG synthesis in rats. Following 27 days on diet and ovulation induction, ovaries were isolated and analyzed in 22 pups per diet. Ovarian phospholipid (n-3) polyunsaturated fatty acid (PUFA) incorporation increased with EPA/DHA ingestion. With significant ovarian (n-3) PUFA or EPA (P < .05) enrichment in the high–n-3 PUFA diets, ova release increased. Although high ALA did not enrich total (n-3), it increased ova release and tissue EPA over low ALA or control. Dietary EPA/DHA more effectively reduced ovarian arachidonic acid levels than dietary ALA. Dietary ALA increased PGF and very high intake reduced PGE, whereas EPA/DHA did not alter PGE or PGF. Enhanced ova release with high (n-3) PUFA intake may be induced via multiple mechanisms including reduced ovarian arachidonic acid. Significant ovarian retention of EPA and DHA enhanced ovulation with unchanged total PGE and PGF. Lack of change in PGE may have resulted from reduced PGE₂ combined with increased PGE₃. When EPA alone was elevated, PGE was reduced, whereas PGF was increased. Results indicate that very high ALA intake enhances ovulation similar to very high EPA/DHA ingestion, an effect potentially mediated via similar patterns of PGF₂α and PGE₂ synthesis.     

Maternal dietary 22 : 6n-3 is more effective than 18 : 3n-3 in increasing the 22 : 6n-3 content in phospholipids of glial cells from neonatal rat brain

One of the debates in infant nutrition concerns whether dietary 18 : 3n-3 (linolenic acid) can provide for the accretion of 22 : 6n-3 (docosahexaenoic acid, DHA) in neonatal tissues. The objective of the present study was to determine whether low or high 18 : 3n-3 v. preformed 22 : 6n-3 in the maternal diet enabled a similar 22 : 6n-3 content in the phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidylserine (PS) of glial cells from whole brain (cerebrum and cerebellum) of 2-week-old rat pups. At parturition, the dams were fed semi-purified diets containing either increasing amounts of 18 : 3n-3 (18 : 2n-6 to 18 : 3n-3 fatty acid ratio of 7.8 : 1, 4.4 : 1 or 1 : 1), preformed DHA, or preformed 20 : 4n-6 (arachidonic acid)+DHA. During the first 2 weeks of life, the rat pups from the respective dams received only their dam's milk. The fatty acid composition of the pups' stomach contents (dam's milk) and phospholipids from glial cells were quantified. The 20 : 4n-6 and 22 : 6n-3 content in the stomach from rat pups at 2 weeks of age reflected the fatty acid composition of the dam's diet. The 20 : 4n-6 content of PE and PS in the glial cells was unaffected by maternal diet treatments. Preformed 22 : 6n-3 in the maternal diet increased the 22 : 6n-3 content of glial cell PE and PS compared with maternal diets providing an 18 : 2n-6 to 18 : 3 n-3 fatty acid ratio of 7.8 : 1, 4.4 : 1 or 1 : 1 (P<0.0001). There was no significant difference in the 20 : 4n-6 and 22 : 6n-3 content of glial cell PC and PI among maternal diet treatments. It was concluded that maternal dietary 22 : 6n-3 is more effective than low or high levels of maternal dietary 18 : 3n-3 at increasing the 22 : 6n-3 content in PE and PS of glial cells from the whole brain of rat pups at 2 weeks of age. The findings from the present study have important implications for human infants fed infant formulas that are devoid of 22 : 6n-3.     

Effects of olive oil and its fractions on oxidative stress and the liver's fatty acid composition in 2,4-Dichlorophenoxyacetic acid-treated rats

Background

Dietary long-chain polyunsaturated fatty acids (LC-PUFA) are of crucial importance for the development of neural tissues. The aim of this study was to evaluate the impact of a dietary supplementation in n-3 fatty acids in female rats during gestation and lactation on fatty acid pattern in brain glial cells phosphatidylethanolamine (PE) and phosphatidylserine (PS) in the neonates.

Methods

Sprague-Dawley rats were fed during the whole gestation and lactation period with a diet containing either docosahexaenoic acid (DHA, 0.55%) and eicosapentaenoic acid (EPA, 0.75% of total fatty acids) or α-linolenic acid (ALA, 2.90%). At two weeks of age, gastric content and brain glial cell PE and PS of rat neonates were analyzed for their fatty acid and dimethylacetal (DMA) profile. Data were analyzed by bivariate and multivariate statistics.

Results

In the neonates from the group fed with n-3 LC-PUFA, the DHA level in gastric content (+65%, P < 0.0001) and brain glial cell PE (+18%, P = 0.0001) and PS (+15%, P = 0.0009) were significantly increased compared to the ALA group. The filtered correlation analysis (P < 0.05) underlined that levels of dihomo-γ-linolenic acid (DGLA), DHA and n-3 docosapentaenoic acid (DPA) were negatively correlated with arachidonic acid (ARA) and n-6 DPA in PE of brain glial cells. No significant correlation between n-3 and n-6 LC-PUFA were found in the PS dataset. DMA level in PE was negatively correlated with n-6 DPA. DMA were found to occur in brain glial cell PS fraction; in this class DMA level was correlated negatively with DHA and positively with ARA.

Conclusion

The present study confirms that early supplementation of maternal diet with n-3 fatty acids supplied as LC-PUFA is more efficient in increasing n-3 in brain glial cell PE and PS in the neonate than ALA. Negative correlation between n-6 DPA, a conventional marker of DHA deficiency, and DMA in PE suggests n-6 DPA that potentially be considered as a marker of tissue ethanolamine plasmalogen status. The combination of multivariate and bivariate statistics allowed to underline that the accretion pattern of n-3 LC-PUFA in PE and PS differ.     

Effect of alpha-linolenic acid supplementation during pregnancy on maternal and neonatal polyunsaturated fatty acid status and pregnancy outcome

BACKGROUND: Maternal essential fatty acid status declines during pregnancy, and as a result, neonatal concentrations of docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (AA, 20:4n-6) may not be optimal. OBJECTIVE: Our objective was to improve maternal and neonatal fatty acid status by supplementing pregnant women with a combination of alpha-linolenic acid (ALA, 18:3n-3) and linoleic acid (LA, 18:2n-6), the ultimate dietary precursors of DHA and AA, respectively. DESIGN: From week 14 of gestation until delivery, pregnant women consumed daily 25 g margarine supplying either 2.8 g ALA + 9.0 g LA (n = 29) or 10.9 g LA (n = 29). Venous blood was collected for plasma phospholipid fatty acid analyses at weeks 14, 26, and 36 of pregnancy, at delivery, and at 32 wk postpartum. Umbilical cord blood and vascular tissue samples were collected to study neonatal fatty acid status also. Pregnancy outcome variables were assessed. RESULTS: ALA+LA supplementation did not prevent decreases in maternal DHA and AA concentrations during pregnancy and, compared with LA supplementation, did not increase maternal and neonatal DHA concentrations but significantly increased eicosapentaenoic acid (20:5n-3) and docosapentaenoic acid (22:5n-3) concentrations. In addition, ALA+LA supplementation lowered neonatal AA status. No significant differences in pregnancy outcome variables were found. CONCLUSIONS: Maternal ALA+LA supplementation did not promote neonatal DHA+AA status. The lower concentrations of Osbond acid (22:5n-6) in maternal plasma phospholipids and umbilical arterial wall phospholipids with ALA+LA supplementation than with LA supplementation suggest only that functional DHA status improves with ALA+LA supplementation.     

Maternal dietary n-6 polyunsaturated fatty acid deprivation does not exacerbate post-weaning reductions in arachidonic acid and its mediators in the mouse hippocampus

Objectives: The present study examines how lowering maternal dietary n-6 polyunsaturated fatty acids (PUFA) (starting from pregnancy) compared to offspring (starting from post-weaning) affect the levels of n-6 and n-3 fatty acids in phospholipids (PL) and lipid mediators in the hippocampus of mice.

Methods: Pregnant mice were randomly assigned to consume either a deprived or an adequate n-6 PUFA diet during pregnancy and lactation (maternal exposure). On postnatal day (PND) 21, half of the male pups were weaned onto the same diet as their dams, and the other half were switched to the other diet for 9 weeks (offspring exposure). At PND 84, upon head-focused high-energy microwave irradiation, hippocampi were collected for PL fatty acid and lipid mediator analyses.

Results: Arachidonic acid (ARA) concentrations were significantly decreased in both total PL and PL fractions, while eicosapentaenoic acid (EPA) concentrations were increased only in PL fractions upon n-6 PUFA deprivation of offspring, regardless of maternal exposure. Several ARA-derived eicosanoids were reduced, while some of the EPA-derived eicosanoids were elevated by n-6 PUFA deprivation in offspring. There was no effect of diet on docosahexaenoic acid (DHA) or DHA-derived docosanoids concentrations under either maternal or offspring exposure.

Discussion: These results indicate that the maternal exposure to dietary n-6 PUFA may not be as important as the offspring exposure in regulating hippocampal ARA and some lipid mediators. Results from this study will be helpful in the design of experiments aimed at testing the significance of altering brain ARA levels over different stages of life.     

Dietary polyunsaturated fat that is low in (n-3) and high in (n-6) fatty acids alters the SNARE protein complex and nitrosylation in rat hippocampus

Docosahexaenoic acid [DHA, 22:6(n-3)] is enriched in brain membrane phospholipids and is important to brain development and function through its influence on neurite outgrowth and neurotransmitter secretion. Fusion of intracellular vesicles with the plasma membrane involving SNARE [soluble N-ethylmaleimide-sensitive fusion (NSF) protein attachment protein receptor] protein assembly, membrane fusion, and then disassembly are events common in membrane extension and neurotransmitter release. We determined whether feeding an (n-3) fatty acid-deficient diet, known to reduce brain phospholipid DHA, alters SNARE protein and SNARE complex expression or protein nitrosylation in the hippocampus of rats. Female rats were fed diets with 1.3 or 0.02% energy (n-3) alpha-linolenic acid from 2 wk before gestation then throughout gestation and lactation (n = 8/diet), and the male offspring were weaned to the maternal diet. Hippocampus phospholipid fatty acids and SNARE proteins were determined in male offspring at 90 d of age. Hippocampus phospholipid DHA was lower and (n-6) docosapentaenoic acid [DPA, 22:5(n-6)] was higher in the (n-3) fatty acid-deficient rats compared with the control group (P < 0.05). Multiplex Western blots using antibodies to syntaxin, synaptosome-associated protein of 25kDa (SNAP-25), and complexin II, showed higher ternary SNARE complexes but no differences in syntaxin, SNAP-25, or complex II expression in hippocampus of the (n-3) fatty acid-deficient rats compared with the control group (P < 0.05). S-nitrosylation of syntaxin was also significantly lower in the (n-3) fatty acid-deficient rats than in the control group. These studies suggest that altered SNARE complex binding or disassembly could be important in explaining the diverse cellular events associated with altered tissue DHA.     

Flaxseed oil and fish-oil capsule consumption alters human red blood cell n-3 fatty acid composition: a multiple-dosing trial comparing 2 sources of n-3 fatty acid

BACKGROUND: An increase in plasma n-3 fatty acid content, particularly eicosapentaenoic acid (20:5n-3; EPA) and docosahexaenoic acid (22:6n-3; DHA), is observed after consumption of fish oil-enriched supplements. Because alpha-linolenic acid (18:3n-3; ALA) is the direct precursor of EPA and DHA, ALA-enriched supplements such as flax may have a similar effect, although this hypothesis has been challenged because of reported low conversion of ALA into DHA. OBJECTIVE: To address this question, we designed a clinical trial in which flax oil, fish-oil, and sunflower oil (placebo group) capsules were given to firefighters (n = 62), a group traditionally exposed to cardiovascular disease risk factors. DESIGN: Firefighters were randomly divided into 6 experimental groups receiving 1.2, 2.4, or 3.6 g flax oil/d; 0.6 or 1.2 g fish oil/d; or 1 g sunflower oil/d for 12 wk. Blood was drawn every 2 wk, and the total phospholipid fatty acid composition of red blood cells was determined. RESULTS: As expected, fish oil produced a rapid increase in erythrocyte DHA and total n-3 fatty acids. The consumption of either 2.4 or 3.6 g flax oil/d (in capsules) was sufficient to significantly increase erythrocyte total phospholipid ALA, EPA, and docosapentaenoic acid (22:5n-3) fatty acid content. There were no differences among groups in plasma inflammatory markers or lipid profile. CONCLUSIONS: The consumption of ALA-enriched supplements for 12 wk was sufficient to elevate erythrocyte EPA and docosapentaenoic acid content, which shows the effectiveness of ALA conversion and accretion into erythrocytes. The amounts of ALA required to obtain these effects are amounts that are easily achieved in the general population by dietary modification.     

Effects of alpha-linolenic acid vs. docosahexaenoic acid supply on the distribution of fatty acids among the rat cardiac subcellular membranes after a short- or long-term dietary exposure

Background

Previous work showed that the functional cardiac effect of dietary alpha-linolenic acid (ALA) in rats requires a long feeding period (6 months), although a docosahexaenoic (DHA) acid-supply affects cardiac adrenergic response after 2 months. However, the total cardiac membrane n-3 polyunsaturated fatty acid (PUFA) composition remained unchanged after 2 months. This delay could be due to a specific reorganization of the different subcellular membrane PUFA profiles. This study was designed to investigate the evolution between 2 and 6 months of diet duration of the fatty acid profile in sarcolemmal (SL), mitochondrial (MI), nuclear (NU) and sarcoplasmic reticulum (SR) membrane fractions.

Methods

Male Wistar rats were randomly assigned to 3 dietary groups (n = 10/diet/period), either n-3 PUFA-free diet (CTL), or ALA or DHA-rich diets. After 2 or 6 months, the subcellular cardiac membrane fractions were separated by differential centrifugations and sucrose gradients. Each membrane profile was analysed by gas chromatography (GC) after lipid extraction.

Results

As expected the n-3 PUFA-rich diets incorporated n-3 PUFA instead of n-6 PUFA in all the subcellular fractions, which also exhibited individual specificities. The diet duration increased SFA and decreased PUFA in SL, whereas NU remained constant. The SR and MI enriched in n-3 PUFA exhibited a decreased DHA level with ageing in the DHA and CTL groups. Conversely, the n-3 PUFA level remained unchanged in the ALA group, due to a significant increase in docosapentaenoic acid (DPA). N-3 PUFA rich diets lead to a better PUFA profile in all the fractions and significantly prevent the profile modifications induced by ageing.

Conclusion

With the ALA diet the n-3 PUFA content, particularly in SR and SL kept increasing between 2 and 6 months, which may partly account for the delay to achieve the modification of adrenergic response.     

Effect of dietary fat level and sesamin on the polyunsaturated fatty acid metabolism in rats

In this study, we examined the effects of sesamin and vegetable oil on the concentrations of polyunsaturated fatty acid (PUFA) and lipids (triacylglycerol, free cholesterol, and phospholipid), and beta-oxidation enzyme activities in the rat liver. Rats were fed a diet containing 5% (low-fat diet) or 20% (high-fat diet) salad oil (rapeseed oil: soybean oil, 7:3) with or without sesamin (0.5% w/w) for 4 wk. As a result, the concentrations of linoleic acid (LA, n-6), alpha-linolenic acid (ALA, n-3), and total PUFA in the liver increased significantly as the result of the high-fat diet. In the high-fat diet groups, sesamin administration decreased the concentrations of LA, ALA, and total PUFA to almost the same level as the low-fat diet group, while it increased the concentrations of dihomo-gamma-linolenic acid (DGLA, n-6) and arachidonic acid (AA, n-6). The activities of carnitine acyltransferase and acyl-CoA dehydrogenase in liver mitochondria were enhanced by the intake of the high-fat diet, and were further enhanced by the administration of sesamin. Peroxisomal acyl-CoA oxidase activity was also enhanced by sesamin, while it was not affected by the dietary fat level. These results suggest that sesamin suppressed the increase of hepatic PUFA concentration caused by feeding the high-fat diet through enhancing the enzyme activities of fatty acid beta-oxidation and PUFA metabolism from LA and ALA.     

Effect of dietary alpha-linolenic acid on thrombotic risk factors in vegetarian men

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.     

孕期及哺乳期n-6/n-3脂肪酸变化对仔鼠脑源性神经营养因子基因表达的影响

目的 探讨孕期及哺乳期n-3 多不饱和脂肪酸(n-3 polyunsaturated fatty acids,n-3 PUFAs)摄入量及其与n-6 PUFAs比例对仔鼠脑源性神经营养因子(brain-derived neurotrophic factor,bdnf)基因表达的影响。方法 使用6~8周龄清洁级C57BL/6J雌性小鼠,随机分为5 组,分别给予n-3 PUFAs缺乏和4种不同含量n-3 PUFAs(n-6/n-3 PUFAs比值分别为15∶1、5∶1、1∶1及1∶5)饲料喂养。小鼠12~14周龄时雌雄合笼交配繁殖,仔鼠断乳后继续行母鼠相同饲料喂养,分别在生后7 d、21 d和3 月时被处死后取脑。同时,分别从n-3 PUFAs缺乏组和n-6/n-3 PUFAs(5∶1)组中选取等量仔鼠,21 d断乳后相互交换饲料喂养至3个月,处死后取脑。采用实时荧光定量PCR技术测定脑皮质bdnf基因mRNA的表达。结果 与n-3 PUFAs缺乏饲料组相比,对于7 d和21 d幼年仔鼠,只有n-6/n-3 PUFAs(1∶5)饲料组bdnf基因mRNA表达量显著升高;对于3 月龄成年仔鼠,各含n-3 PUFAs饲料组bdnf基因mRNA的表达均升高。对于孕期和哺乳期n-3 PUFAs缺乏饲料组仔鼠,断乳后给予含n-3 PUFAs饲料喂养未能提升脑皮质bdnf基因mRNA表达;而孕期和哺乳期含n-3 PUFAs饲料喂养的仔鼠,断乳后给予n-3 PUFAs缺乏饲料喂养时,脑皮质bdnf基因mRNA表达量见一定程度的升高。结论 孕期及哺乳期可能需要较高的n-3 PUFAs摄入,才能满足幼年期诱导脑bdnf表达之需。保证生命早期n-3 PUFAs的适量摄入,有助于维持成年期bdnf的正常表达。     

Decreasing linoleic acid with constant alpha-linolenic acid in dietary fats increases (n-3) eicosapentaenoic acid in plasma phospholipids in healthy men

High linoleic acid (LA) intakes have been suggested to reduce alpha-linolenic acid [ALA, 18:3(n-3)] metabolism to eicosapentaenoic acid [EPA, 20:5(n-3)] and docosahexaenoic acid [DHA, 22:6(n-3)], and favor high arachidonic acid [ARA, 20:4(n-6)]. We used a randomized cross-over study with men (n = 22) to compare the effect of replacing vegetable oils high in LA with oils low in LA in foods, while maintaining constant ALA, for 4 wk each, on plasma (n-3) fatty acids. Nonvegetable sources of fat, except fish and seafoods, were unrestricted. We determined plasma phospholipid fatty acids at wk 0, 2, 4, 6, and 8, and triglycerides, cholesterol, serum CRP, and IL-6, and platelet aggregation at wk 0, 4, and 8. LA and ALA intakes were 3.8 +/- 0.12% and 1.0 +/- 0.05%, and 10.5 +/- 0.53% and 1.1 +/- 0.06% energy with LA:ALA ratios of 4:0 and 10:1 during the low and high LA diets, respectively. The plasma phospholipid LA was higher and EPA was lower during the high than during the low LA diet period (P < 0.001), but DHA declined over the 8-wk period (r = -0.425, P < 0.001). The plasma phospholipid ARA:EPA ratios were (mean +/- SEM) 20.7 +/- 1.52 and 12.9 +/- 1.01 after 4 wk consuming the high or low LA diets, respectively (P < 0.001); LA was inversely associated with EPA (r = -0.729, P < 0.001) but positively associated with ARA:EPA (r = 0.432, P < 0.001). LA intake did not influence ALA, ARA, DPA, DHA, or total, LDL or HDL cholesterol, CRP or IL-6, or platelet aggregation. In conclusion, high LA intakes decrease plasma phospholipid EPA and increase the ARA:EPA ratio, but do not favor higher ARA.     

The use of docosahexaenoic acid supplementation to ameliorate the hyperactivity of rat pups induced by in utero ethanol exposure

It has been demonstrated thatin utero ethanol (EtOH) exposure induces hyperactive behavior and learning disturbances in offspring. In order to investigate the effects of docosahexaenoic acid (DHA) on these neurobehavioral dysfunctions of rat pups induced byin utero EtOH exposure, pregnant Wistar rats were divided into four treatment groups depending on the type of oil added to the diet and drinking water as follows; (a) 5% safflower oil with tap water (TW/n-6), (b) 3% safflower oil and 2% DHA with tap water (TW/n-3), (c) 5% safflower oil with 10%-EtOH (ET/n-6), (d) 3% safflower oil and 2% DHA with 10%-EtOH (ET/n-3) at gestational day (GD) 7. 10%-EtOH was administered to dams in ET/n-6 and ET/n-3 groups from GD 7 to the pups’ weaning (postnatal week 4), and all pups were fed with the same diet that was given to their dams during the entire examination period. The open-field test and the water E-maze test were conducted for all pups, and a spontaneous motor activity test and the Sidman electric shock avoidance test were performed for some of male pups. Amounts of monoamine metabolites in striatum were then determined, and fatty acid analyses of total brain lipids were performed. The male pups in the ET/n-6 group showed significandy more rearing and square-crossing movements in the open-field test, and significandy higher spontaneous motor activity during the dark period in the daily cycle compared to the males in the TW/n-6 group. The male pups in the ET/n-3 group showed fewer of these behaviors in the open-field test compared to the ET/n-6 group males, and a normal pattern of spontaneous motor activity. Learning disturbance induced byin utero EtOH exposure was not observed in the E-shaped water maze, but was observed in the avoidance rates in the Sidman electric shock avoidance test. However, there was no significant modifying effect of DHA on the avoidance rates in EtOH exposed pups. The analysis of the fatty acid composition of total lipids in the brains of the pups revealed high levels of DHA in the diet reflected an increased level of brain DHA and caused a decreased level of the brain arachidonic acid. Retroco nversion from DHA to eicosapentaenoic acid was also observed. However, there was no significant effect of DHA on the levels of monoamine metabolites. These results support the hypothesis that DHA can counteract the attention deficit hyperactivity disorder. This is the secondary publication of the paper entitled, “The effects of docosahexaenoic acid on brain function in rats showing the symptoms of fetal alcohol effects” which appeared in “Alcohol and Biomedical Research” (Alcohol to igakuseibutsugaku [in Japanese]), Tokyo; Toyoshoten. 1997:132-8.     

A practical approach to increasing intakes of n-3 polyunsaturated fatty acids: use of novel foods enriched with n-3 fats

OBJECTIVES: To assess the effects of providing a wide range of foodstuffs containing n-3 polyunsaturated fatty acids (PUFA), occurring naturally or from fortification, on intake and blood and tissue proportions of n-3 PUFA. DESIGN: Before/after dietary intervention study. SETTING: Adelaide, Australia. SUBJECTS: 16 healthy males recruited from the community. INTERVENTIONS: Subjects were provided with a range of foodstuffs naturally containing n-3 PUFA (fresh fish, canned fish, flaxseed meal, canola oil) and items fortified with fish oil (margarine spread, milk, sausages, luncheon meat, french onion dip). Food choices were left to the discretion of each subject. Intake was estimated by diet diary. Blood was collected at-2, 0, 2, and 4 weeks for fatty acid analysis. MAIN OUTCOME MEASURES: Dietary intakes; plasma, platelet, and mononuclear cell phospholipid fatty acids. RESULTS: Consumption of n-3 PUFA increased significantly: alpha-linolenic acid (ALA) from 1.4 to 4.1 g/day (P<0.001), eicosapentaenoic acid (EPA) from 0.03 to 0.51 g/day (P<0.001), and docosahexaenoic acid (DHA) from 0.09 to 1.01 g/day (P<0.001). Linoleic acid (LA) intake decreased from 13.1 to 9.2 g/day (P<0.001). The proportions of EPA and DHA increased significantly in all phospholipid pools examined; plasma EPA from 1.13% of total fatty acids to 3.38% (P<0.001) and DHA from 3.76 to 7.23% (P<0.001); mononuclear cell EPA from 0.40 to 1.25% (P<0.001) and DHA from 2.33 to 4.08% (P<0.001); platelet EPA from 0.41 to 1.2% (P<0.001) and DHA from 1.64 to 3.07% (P<0.001). CONCLUSION: Incorporating fish oil into a range of novel commercial foods provides the opportunity for wider public consumption of n-3 PUFA with their associated health benefits. SPONSORSHIP: Dawes Scholarship, Royal Adelaide Hospital.