Maternal parity and diet (n-3) polyunsaturated fatty acid concentration influence accretion of brain phospholipid docosahexaenoic acid in developing rats

The long-chain PUFA, docosahexaenoic acid [22:6(n-3), DHA], a major component of neuronal membrane phospholipids, accumulates in brain during late prenatal and early neonatal development and is essential for optimal attentional and cognitive function. Because all nutrition is supplied to the developing fetus/neonate by the mother and maternal DHA status is affected by parity, this study examined the effects of maternal diet and parity on DHA accretion in the developing brain. Whole brain total phospholipid fatty acid composition was determined by TLC and GC in weanling male Long-Evans rats (n = 5) from the 1st, 2nd, 3rd, or 4th litters of dams fed diets containing alpha-linolenic acid (ALA), containing ALA and preformed DHA (ALA + DHA), or lacking ALA (low-ALA). First-litter low-ALA offspring exhibited a decrease in phospholipid fatty acid DHA content to 68% of 1st-litter ALA pups. DHA in 2nd-litter low-ALA pups was further decreased to 55% of 1st-litter ALA pups, but further decreases were not observed in subsequent litters. DHA levels increased 15-20% in 2nd to 4th-litter ALA + DHA pups and 11% in 4th-litter ALA pups compared with 1st-litter ALA pups. These findings demonstrate that maternal diet and parity interact to affect offspring brain DHA status and suggest that maternal multiparity may place offspring at greater risk of decreased accretion of brain DHA if the maternal diet contains insufficient (n-3) PUFA.     

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.     

Testes of obese rats are highly responsive to n-3 long-chain fatty acids

The present study investigated whether fatty acid compositions of testes are affected by the obese condition and dietary n-3 long-chain fatty acid (LCFA) intake. Male lean and obese Zucker rats were fed a 15?% (w/w, total diet) fat diet containing either 0 or 5·0?% (w/w, total fatty acids) n-3 LCFA for 8 weeks. Reproductive organ weights, sperm morphology and fatty acid composition of phosphatidylcholine (PC), and phosphatidylethanolamine (PE) of testes were analysed. The obese rats had significantly (P?相似文献   

Dietary fatty acid composition in pregnancy alters neurite membrane fatty acids and dopamine in newborn rat brain

The importance of maternal dietary fatty acids on arachidonic acid [AA; 20:4(n-6)] and docosahexaenoic acid [DHA; 22:6(n-3)] in fetal brain nerve growth cone membranes and monoaminergic neurotransmitters was investigated. Rats were fed purified diets containing 20 g/100 g safflower oil with 74.3% 18:2(n-6), 0.2% 18:3(n-3), soybean oil with 55.4% 18:2(n-6), 7.7% 18:3(n-3) or high fish oil with 24.6% 22:6(n-3) through gestation. Tissue for rats within a litter were pooled at birth, brain growth cone membranes prepared and phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) fatty acids quantified by gas-liquid chromatography. Dopamine, serotonin, and the metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid, and 5-hydroxyindolacetic acid were quantified by HPLC. Growth cone membranes from offspring of rats fed safflower oil had significantly lower, and offspring of rats fed high 22:6(n-3) fish oil had significantly higher 22:6(n-3) in PE, PS and PI than the soybean oil group. The growth cone membrane PC, PE and PS 20:4(n-6) was significantly lower in the fish oil than in the soybean or safflower oil groups. Serotonin concentration was significantly higher in brain of offspring in the safflower oil compared with the soybean oil group. The newborn brain dopamine was inversely related to PE DHA and PS DHA (P < 0.001), but positively related to PC AA (P < 0.05). These studies show that maternal dietary fatty acids may alter fetal brain growth cone (n-6) and (n-3) fatty acids, and neurotransmitters involved in neurite extension, target finding and synaptogenesis. The functional importance, however, is not known at this time.     

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.     

trans Fatty acids in human milk are inversely associated with concentrations of essential all-cis n-6 and n-3 fatty acids and determine trans, but not n-6 and n-3, fatty acids in plasma lipids of breast-fed infants.

BACKGROUND: Human milk fatty acids vary with maternal dietary fat composition. Hydrogenated dietary oils with trans fatty acids may displace cis n-6 and n-3 unsaturated fatty acids or have adverse effects on their metabolism. The effects of milk trans, n-6, and n-3 fatty acids in breast-fed infants are unclear, although n-6 and n-3 fatty acids are important in infant growth and development. OBJECTIVE: We sought to determine the relations between trans and cis unsaturated fatty acids in milk and plasma phospholipids and triacylglycerols of breast-fed infants, and to identify the major maternal dietary sources of trans fatty acids. DESIGN: We collected milk from 103 mothers with exclusively breast-fed 2-mo-old infants, blood from 62 infants, and 3-d dietary records from 21 mothers. RESULTS: Mean (+/-SEM) percentages of trans fatty acids were as follows: milk, 7.1 +/- 0.32%; infants' triacylglycerols, 6.5 +/- 0. 33%; and infants' phospholipids, 3.7 +/- 0.16%. Milk trans fatty acids, alpha-linolenic acid (18:3n-3), arachidonic acid (20:4n-6), docosahexaenoic acid (22:6n-3) (P < 0.001), and linoleic acid (18:2n-6) (P = 0.007) were each related to the same fatty acid in infant plasma phospholipids. Milk trans fatty acids were inversely related to milk 18:2n-6 and 18:3n-3, but not to milk or infant plasma 20:4n-6 or 22:6n-3. trans Fatty acids represented 7.7% of maternal total fat intake (2.5% of total energy); the major dietary sources were bakery products and breads (32%), snacks (14%), fast foods (11%), and margarines and shortenings (11%). CONCLUSIONS: There were comparable concentrations of trans fatty acids in the maternal diet, breast milk, and plasma triacylglycerols of breast-fed infants. Prepared foods were the major dietary source of trans fatty acids.     

Dietary n-3 polyunsaturated fatty acids: modification of rat cardiac lipids and fatty acid composition

The effects of 5, 10 and 20% dietary menhaden oil (MO) on the composition of heart lipid classes and fatty acids were studied. Male Sprague-Dawley rats were fed ad libitum 0, 5, 10 and 20% MO for 3 wk. The heart phosphoglyceride content and composition and cholesterol were unchanged by dietary MO. A nonlinear dose-response relationship was observed between dietary MO levels and fatty acid compositional changes. Cardiolipin, choline (PC), ethanolamine (PE) and serine/inositol (PS/PI) phosphoglycerides showed an incorporation of n-3 fatty acids, eicosapentaenoic (20:5n-3) and docosahexaenoic (22:6n-3), between the control and 5% MO group, a plateau between the 5 and 10% MO groups and a further increase at the 20% MO level. The initial reduction in 20:4n-6 content remained unchanged as dietary MO increased except in PE where a further reduction was found at the 20% MO level. Dietary MO did not significantly change the 20:4n-6 content in neutral lipids. Linoleic acid content was most resistant to dietary MO removal. The level of 18:2n-6 was significantly lowered in heart PC when rats were fed 10% MO. No significant differences were found in PS/PI. In PE and NL significant differences occurred only when rats were fed 20% MO. The significant fatty acid modifications of heart lipid and PL found between the control and lowest level of dietary MO (5%) suggest that dietary fish oil supplementation in human diets may not be required for this effect.     

Dietary n-3 and n-6 fatty acids alter avian metabolism: molecular-species composition of breast-muscle phospholipids

The effects of diets high in n-3 polyunsaturated fatty acids (PUFA; provided by fish oil), n-6 PUFA (sunflower oil) or in more-saturated fatty acids (tallow) on the distribution of subclasses of choline phospholipids (PC) and ethanolamine phospholipids (PE) from the breast muscle of broiler chickens were examined. Supplementation with the different fatty acids had no effect on the distribution of phospholipid subclasses. Feeding sunflower oil or tallow gave a molecular-species profile similar in both fatty acid subtype and proportion. In the diacyl PC phospholipids, 16 : 0-18 : 1n-9 and 16 : 0-18 : 2n-6 accounted for approximately 60 % of the total molecular species, whereas for the alkylenyl PC the predominant species were 16 : 0-18 : 1n-9 and 16 : 0-20 : 4n-6. Of the diacyl PE the dominant species was 18 : 0-20 : 4n-6 which accounted for 50 % of the molecular species, and of the alkylenyl PE the dominant species were 16 : 0-18 : 1n-9, 16 : 0-20 : 4n-6 and 18 : 0-20 : 4n-6. Supplementation with fish oil significantly increased levels of both eicosapentaenoic acid (20 : 5n-3) and docosahexaenoic acid (22 : 6n-3) in PC and PE when compared with either sunflower oil or tallow supplementation. The increase in the n-3 PUFA incorporation was associated with a corresponding decrease in the proportion of arachidonic acid (20 : 4n-6) in both PC and PE. Different dietary fats induce different patterns of fatty acid incorporation and substitution in the sn-2 position of the diacyl and alkylenyl PC and PE of avian breast muscle, and this finding is indicative of selective acyl remodelling in these two phospholipids.     

Intakes of essential n-6 and n-3 polyunsaturated fatty acids among pregnant Canadian women

BACKGROUND: Fetal growth requires n-3 docosahexaenoic acid (DHA), which is derived from the essential n-3 fatty acids in the maternal diet. DHA is accumulated in the developing brain and is critical for normal neural and visual function. Available estimates suggest that 67 mg DHA/d is accumulated by the fetus during the third trimester of gestation. Little is known about n-3 fatty acid intakes in pregnant women, although human milk concentrations of DHA have decreased in recent years. OBJECTIVE: We prospectively determined the n-3 and n-6 fatty acid intakes of 55 pregnant Canadian women. DESIGN: A food-frequency questionnaire was completed at 28 and 35 wk, and plasma n-3 and n-6 fatty acids were measured at 35 wk gestation. The fatty acid composition of approximately 500 foods was analyzed to allow analysis of dietary intakes from specific foods. RESULTS: Intakes, as a percentage of energy, were (macro x +/- SEM) total fat, 28.0 +/- 3.6%; saturated fat, 9.8 +/- 0.3%; monounsaturated fat, 11.2 +/- 0.4%; polyunsaturated fat, 4.7 +/- 0.2%; linoleic acid, 3.9 +/- 0.2%; and alpha-linolenic acid, 0.54 +/- 0.05%. The daily intakes (range) were 160 +/- 20 (24-524) mg DHA/d, 121 +/- 8 (15-301) mg arachidonic acid/d, and 78 +/- 2 (4-125) mg eicosapentaenoic acid/d. The plasma phospholipids had (mg/100 g fatty acid) 5.0 +/- 0.18 DHA, 8.7 +/- 0.18 arachidonic acid, and 0.52 +/- 0.32 eicosapentaenoic acid. CONCLUSION: The low intake of DHA among some pregnant women highlights the need for studies to address the functional significance of maternal fat intakes during pregnancy on fetal development.     

Effect of dietary n-3 fatty acids on the composition of long- and very-long-chain polyenoic fatty acid in rat retina

The effect of dietary supplementation with n-3 fatty acids, primarily docosahexaenoic acid (DHA) with high purity, on the fatty acid composition, especially very-long-chain fatty acids (VLCFA) longer than DHA, with four or six double bonds, in the rod outer segment (ROS) membranes of young Sprague-Dawley rats was investigated. After several weeks of feeding, diets high in n-3 fatty acids increased the DHA level significantly, while there were decreased levels of most n-6 fatty acids, such as arachidonic acid and 22:5n-6. Six kinds of VLCFA were detected by gas chromatography-mass spectrometry (GC-MS). Feeding a high n-3 fatty acid diet significantly increased the content of some n-3 VLCFAs such as 26:4n-3 and 30:4n-3 in ROS membranes, but not all detected n-3 VLCFAs. This study demonstrates that the dietary level of n-3 fatty acids not only affects the level of DHA, but also the levels of VLCFA in ROS membranes.     

Effects of repeated gestation and lactation on milk n-6 fatty acid composition in rats fed on a diet rich in 18:2n-6 or 18:3n-6.

The present study examined the effect of repeated gestation and lactation on the levels of long-chain n-6 polyunsaturated fatty acids in rat milk fat, and examined whether such levels might be modulated by supplementing the diet of the lactating dams with either (g/kg) 50 safflower oil (SFO; containing 800 g 18:2n-6/kg), or 50 evening primrose oil (EPO; containing 720 g 18:2n-6 and 90 g 18:3n-6/kg). The milk was collected at three different times (days 1, 8 and 15) in each given lactation period from female Sprague-Dawley rats which were successively bred for four pregnancies and lactations. Results showed that dietary fat and breeding frequency had no significant effects on milk triacylglycerol content, but they modified the pattern of milk fatty acids in both triacylglycerol and phospholipid fractions. After three or four successive breedings rats fed on EPO produced milk containing less saturated but more monounsaturated and polyunsaturated fatty acids compared with those fed on SFO. During the course of lactation the levels of n-6 metabolites, e.g. 18:3n-6, 20:3n-6 and 20:4n-6, in milk fat declined progressively. However, they were consistently higher in the EPO group than in the SFO group. These findings suggest that the levels of long-chain n-6 metabolites in the milk fat may be increased through supplementing the maternal diet with 18:3n-6.     

Repletion with (n-3) fatty acids reverses bone structural deficits in (n-3)-deficient rats

(n-3) PUFA deficiency and repletion effects on bone mechanical properties have not been examined. The primary research aim was to evaluate whether changes in the fatty acid composition of bone tissue compartments previously reported to influence bone formation rates would affect bone modeling and mechanical properties. In this investigation, three groups of rats were studied, second generation (n-3)-deficient, (n-3)-repleted, and a control (n-3)-adequate. The (n-3)-adequate diet contained alpha-linolenic acid [LNA, 18:3(n-3), 2.6% of total fatty acids] and docosahexaenoic acid [DHA, 22:6(n-3), 1.3% of total fatty acids]. Fatty acid composition of the hindlimb tissues (bone and muscle) of chronically (n-3)-deficient rats revealed a marked increase in (n-6) PUFA [20:4(n-6), 22:4(n-6), and 22:5(n-6)] and a corresponding decrease in (n-3) PUFA [18:3(n-3), 20:5(n-3), 22:5(n-3) and 22:6(n-3)]. Measurement of bone mechanical properties (energy to peak load) of tibiae showed that (n-3) deficiency diminished structural integrity. Rats repleted with (n-3) fatty acids demonstrated accelerated bone modeling (cross-sectional geometry) and an improved second moment in tibiae compared with control (n-3)-adequate rats after 28 d of dietary treatment. This study showed that repletion with dietary (n-3) fatty acids restored the ratio of (n-6)/(n-3) PUFA in bone compartments and reversed compromised bone modeling in (n-3)-deficient rats.     

Ethnic differences in early pregnancy maternal n-3 and n-6 fatty acid concentrations: an explorative analysis

Ethnicity-related differences in maternal n-3 and n-6 fatty acid status may be relevant to ethnic disparities in birth outcomes observed worldwide. The present study explored differences in early pregnancy n-3 and n-6 fatty acid composition of maternal plasma phospholipids between Dutch and ethnic minority pregnant women in Amsterdam, the Netherlands, with a focus on the major functional fatty acids EPA (20 : 5n-3), DHA (22 : 6n-3), dihomo-gamma-linolenic acid (DGLA; 20 : 3n-6) and arachidonic acid (AA; 20 : 4n-6). Data were derived from the Amsterdam Born Children and their Development (ABCD) cohort (inclusion January 2003 to March 2004). Compared with Dutch women (n 2443), Surinamese (n 286), Antillean (n 63), Turkish (n 167) and Moroccan (n 241) women had generally lower proportions of n-3 fatty acids (expressed as percentage of total fatty acids) but higher proportions of n-6 fatty acids (general linear model; P < 0.001). Ghanaian women (n 54) had higher proportions of EPA and DHA, but generally lower proportions of n-6 fatty acids (P < 0.001). Differences were most pronounced in Turkish and Ghanaian women, who, by means of a simple questionnaire, reported the lowest and highest fish consumption respectively. Adjustment for fish intake, however, hardly attenuated the differences in relative EPA, DHA, DGLA and AA concentrations between the various ethnic groups. Given the limitations of this observational study, further research into the ethnicity-related differences in maternal n-3 and n-6 fatty acid patterns is warranted, particularly to elucidate the explanatory role of fatty acid intake v. metabolic differences.     

Docosahexaenoic acid and n-6 docosapentaenoic acid supplementation alter rat skeletal muscle fatty acid composition

Background  

Docosahexaenoic acid (22:6n-3, DHA) and n-6 docosapentaenoic acid (22:5n-6, DPAn-6) are highly unsaturated fatty acids (HUFA, ≥ 20 carbons, ≥ 3 double bonds) that differ by a single carbon-carbon double bond at the Δ19 position. Membrane 22:6n-3 may support skeletal muscle function through optimal ion pump activity of sarcoplasmic reticulum and electron transport in the mitochondria. Typically n-3 fatty acid deficient feeding trials utilize linoleic acid (18:2n-6, LA) as a comparison group, possibly introducing a lower level of HUFA in addition to n-3 fatty acid deficiency. The use of 22:5n-6 as a dietary control is ideal for determining specific requirements for 22:6n-3 in various physiological processes. The incorporation of dietary 22:5n-6 into rat skeletal muscles has not been demonstrated previously. A one generation, artificial rearing model was utilized to supply 22:6n-3 and/or 22:5n-6 to rats from d2 after birth to adulthood. An n-3 fatty acid deficient, artificial milk with 18:2n-6 was supplemented with 22:6n-3 and/or 22:5n-6 resulting in four artificially reared (AR) dietary groups; AR-LA, AR-DHA, AR-DPAn-6, AR-DHA+DPAn-6. A dam reared group (DAM) was included as an additional control. Animals were sacrificed at 15 wks and soleus, white gastrocnemius and red gastrocnemius muscles were collected for fatty acid analyses.     

Genetic variants of the FADS1 FADS2 gene cluster are associated with altered (n-6) and (n-3) essential fatty acids in plasma and erythrocyte phospholipids in women during pregnancy and in breast milk during lactation

The enzymes encoded by fatty acid desaturase (FADS) 1 and FADS2 are rate-limiting enzymes in the desaturation of linoleic acid [LA; 18:2(n-6)] to arachidonic acid [ARA; 20:4(n-6)], and alpha-linolenic acid [ALA; 18:3(n-3)] to eicosapentaenoic acid [EPA; 20:5(n-3)] and docosahexaenoic acid [DHA; 22:6(n-3)]. ARA, EPA, and DHA play central roles in infant growth, neural development, and immune function. The maternal ARA, EPA, and DHA status in gestation influences maternal-to-infant transfer and breast milk provides fatty acids for infants after birth. We determined if single nucleotide polymorphisms in FADS1 and FADS2 influence plasma phospholipid and erythrocyte ethanolamine phosphoglyceride (EPG) (n-6) and (n-3) fatty acids of women in pregnancy or their breast milk during lactation. We genotyped rs174553, rs99780, rs174575, and rs174583 in the FADS1 FADS2 gene cluster and analyzed plasma and erythrocyte fatty acids and dietary intake for 69 pregnant women and breast milk for a subset of 54 women exclusively breast-feeding at 1 mo postpartum. Minor allele homozygotes of rs174553(GG), rs99780(TT), and rs174583(TT) had lower ARA but higher LA in plasma phospholipids and erythrocyte EPG and decreased (n-6) and (n-3) fatty acid product:precursor ratios at 16 and 36 wk of gestation. Breast milk fatty acids were influenced by genotype, with significantly lower 14:0, ARA, and EPA but higher 20:2(n-6) in the minor allele homozygotes of rs174553(GG), rs99780(TT), and rs174583(TT) and lower ARA, EPA, 22:5(n-3), and DHA in the minor allele homozygotes G/G of rs174575. We showed that genetic variants of FADS1 and FADS2 influence blood lipid and breast milk essential fatty acids in pregnancy and lactation.     

Human milk: maternal dietary lipids and infant development

Human milk provides all the dietary essential fatty acids, linoleic acid (LA; 18:2n-6) and alpha-linolenic acid (18:3n-3), as well as their longer-chain more-unsaturated metabolites, including arachidonic acid (20:4n-6) and DHA (22:6n-3) to support the growth and development of the breast-fed infant. Human milk levels of LA have increased in Westernized nations from mean levels (g/100 g total fatty acids) of 6 to 12-16 over the last century, paralleling the increase in dietary intake of LA-rich vegetable oils. DHA levels (g/100 g total milk fatty acids) vary from 1% and are lowest in countries in which the intake of DHA from fish and other animal tissue lipids is low. The role of DHA in infant nutrition is of particular importance because DHA is accumulated specifically in the membrane lipids of the brain and retina, where it is important to visual and neural function. An important question is the extent to which many human diets that contain low amounts of n-3 fatty acids may compromise human development. The present paper reviews current knowledge on maternal diet and human milk fatty acids, the implications of maternal diet as the only source of essential fatty acids for infant development both before and after birth, and recent studies addressing the maternal intakes and milk DHA levels associated with risk of low infant neural system maturation.     

Ingestion of fish oil or a derived n-3 fatty acid concentrate containing eicosapentaenoic acid (EPA) affects fatty acid compositions of individual phospholipids of rat brain, sciatic nerve and retina

The effect of feeding redfish (Sebastes marinus or mantella) oil or a derived n-3 fatty acid concentrate containing eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) on the fatty acid compositions of individual phospholipids in selected neural tissues was studied in growing male rats. Control animals were given sunflower oil in the diet for the 5-wk feeding trial. Lipid analyses revealed that EPA (20:5n-3) became significantly enriched in all phospholipid fractions (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine and phosphatidylinositol) in the tissues studied (brain, retina and sciatic nerve) in the two n-3 fatty acid dietary groups relative to controls. Corresponding changes were also found in the 22:5n-3 contents of these tissues, whereas little or no significant elevation in DHA (22:6n-3) was found. In contrast, the percentages by weight of the n-6 fatty acids including 18:2n-6, 20:4n-6 (arachidonic acid, AA), 22:4n-6 and 22:5n-6 were generally lower in the various phospholipids/tissues of the animals given fish oil or the n-3 fatty acid concentrate; the levels of 22:5n-6 and 22:4n-6 were markedly affected in this regard. These results indicate that dietary n-3 fatty acids (as EPA plus DHA) can greatly affect the fatty acid compositions of the various membrane phospholipids in nervous tissues within a relatively short time. These biochemical alterations may be important for functional changes including altered membrane fluidity, cellular responses, ion transport and the biosyntheses of AA- and EPA-derived prostaglandins and leukotrienes.     

Are the n-3 fatty acids from dietary fish oil deposited in the triglyceride stores of adipose tissue?

Adipose tissue is the chief reservoir of the essential fatty acids (n-3 and n-6). To study the incorporation of the dietary n-3 fatty acids eicosapentaenoic acid (EPA) (20:5) and docosahexaenoic acid (DHA) (22:6), and a unique monounsaturated fatty acid, cetoleic acid (22:1n-11), into adipose tissue, rabbits were fed two different processed fish oils: MaxEPA (high in EPA and DHA; Seven Sea Ltd, Hull, UK) and herring oil (high in cetoleic acid). EPA and DHA increased from 0% of total adipose tissue fatty acid, in the adipose tissue of control rabbits to 2.2% and 4.9%, respectively, in MaxEPA-fed rabbits. The DHA-to-EPA ratio in the adipose tissue was higher than that in the diet, indicating alternative metabolic pathways for EPA. In the adipose tissue of herring-oil-fed rabbits, cetoleic acid increased from 0% to 7.9% of total fatty acids. The deposition of EPA and DHA was 1.8% and 2.8%, respectively. Our data indicated that these unique long-chain unsaturated fatty acids from dietary fish oils were readily incorporated into the fat stores from whence they could be mobilized.     

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.     

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.