Peripartal feeding strategy with different n-6: n-3 ratios in sows: effects on sows' performance, inflammatory and periparturient metabolic parameters

The present study aimed to investigate the effects of two lactation sow feeds, differing in n-6:n-3 ratio, given to sows before parturition on body condition and feed intake, periparturient metabolism (leptin, insulin, triiodothyronine (T3) and thyroxine (T4)), inflammatory parameters (TNFalpha, IL-6, serum amyloid A (SAA)) and on piglet performance (birth weight, survivability). The feed contained either a low (supplemented with fish oil; f groups) or high (supplemented with sunflower-seed oil; s groups) n-6:n-3 ratio and was administered from 8 d (f8, s8) or 3 d (f3, s3) before parturition until weaning. The level of inclusion of the oil sources was 2 %. Seventy-two sows were randomly allocated 8 d before expected farrowing into four groups: f3, f8, s3, s8. Type of feed had a significant influence on the sows' feed intake during the first 2 d of lactation (s < f), leptin on days 4, 3 and 2 before parturition (f < s), insulin on day 1 after parturition (f < s), T4 on the day before parturition (s < f) and rectal temperature on the day after parturition (f < s). Onset of administration of the feed (3 v. 8 d) had significant effects on leptin on day 2 before parturition (8 < 3), insulin on day 4 before parturition (3 < 8), T3 on day 4 before parturition and on the day after parturition (3 < 8), SAA on day 3 after parturition (8 < 3) and piglet weight during the first days postpartum (3 < 8). In conclusion, under the present conditions, a lactation feed low in n-6:n-3 ratio administered from 8 d before farrowing ensures improved feed intake during the first days postpartum and was associated with a better metabolic change and inflammatory profile in sows in the periparturient period.     

The effects of obesity-associated insulin resistance on mRNA expression of peroxisome proliferator-activated receptor-gamma target genes, in dogs

Visceral adipose tissue and skeletal muscle have central roles in determining whole-body insulin sensitivity. The peroxisome proliferator-activated receptor-gamma (PPARgamma) is a potential mediator of insulin sensitivity. It can directly modulate the expression of genes that are involved in glucose and lipid metabolism, including GLUT4, lipoprotein lipase (LPL) and adipocytokines (leptin and adiponectin). In this study, we aimed to determine the effects of obesity-associated insulin resistance on mRNA expression of PPARgamma and its target genes. Dogs were studied when they were lean and at the end of an overfeeding period when they had reached a steady obese state. The use of a sensitive, real-time PCR assay allowed a relative quantification of mRNA expression for PPARgamma, LPL, GLUT4, leptin and adiponectin, in adipose tissue and skeletal muscle. In visceral adipose tissue and/or skeletal muscle, mRNA expression of PPARgamma, LPL and GLUT4 were at least 2-fold less in obese and insulin-resistant dogs compared with the same animals when they were lean and insulin-sensitive. The mRNA expression and plasma concentration of leptin was increased, whereas the plasma level and mRNA expression of adiponectin was decreased, by obesity. In adipose tissue, PPARgamma expression was correlated with leptin and adiponectin. These findings, in an original model of obesity induced by a prolonged period of overfeeding, showed that insulin resistance is associated with a decrease in PPARgamma mRNA expression that could dysregulate expression of several genes involved in glucose and lipid metabolism.     

2-OHOA supplementation reduced adiposity and improved cardiometabolic risk to a greater extent than n-3 PUFA in obese mice

ObjectiveWe aimed to assess whether 2-hydroxyoleic acid (2-OHOA) and n-3 polyunsaturated fatty acids (PUFA) could counteract changes on adipokine secretion and cardiometabolic risk biomarkers associated with high-fat diet-induced obesity in mice.MethodsFemale ICR/CD1 mice (8 weeks old) were divided into four groups receiving different diets (n = 8/group): (1) standard chow (control) for 18 weeks; (2) 22% fat for 4 weeks + 60% fat for 14 weeks (obesogenic diet, OD); 3) OD + 2-OHOA (1500 mg kg^?1 diet) for the last 6 weeks (ODHO); and 4) OD + n-3 PUFA (eicosapentaenoic + docosahexaenoic acids, 1500 + 1500 mg kg^?1 diet) for the last 6 weeks (OD-N3). After 18 weeks, body weight, periovarian visceral fat, heart and liver weights were measured, as well as cardiometabolic parameters (systolic and diastolic blood pressure, blood glucose, insulin, HOMA index, triglycerides, total cholesterol, apolipoproteins A1 and E), plasma adipokines and inflammatory proteins (leptin, adiponectin, plasminogen activator inhibitor 1 [PAI1], soluble E-selectin [sE-selectin], matrix metalloproteinase-9 [MMP-9], fibrinogen, soluble intercellular adhesion molecule [sICAM] and soluble vascular adhesion molecule [sVCAM]), and secretion of pro-inflamatory cytokines and inflammatory biomarkers from periovarian adipocytes.ResultsOD mice had greater body and heart weights, and plasma leptin, and lower adiponectin and resistin secretion from adipocytes. Supplementation with 2-OHOA reduced body and heart weights, blood pressure, triglycerides and leptin, and restored adiponectin and resistin secretion, while n-3 PUFA only reduced triglyceride levels (all P < 0.05).Conclusion2-OHOA supplementation was more effective in reducing adiposity, modulating adipokine secretion and ameliorating cardiometabolic risk than n-3 PUFA.     

不同n-6/n-3多不饱和脂肪酸构成比对高脂饲料喂养大鼠脂联素和糖脂代谢及抗氧化能力的影响

目的探讨高脂饲料喂养条件下,不同n-6/n-3多不饱和脂肪酸(polyunsaturated fatty acid,PUFA)构成比对大鼠脂联素和糖脂代谢及抗氧化能力的影响。方法50只雄性Wistar大鼠按体重随机分为5组:1个普通饲料组(脂肪供能比17%,n-6/n-3PUFA=5∶1)和4个高脂饲料组(脂肪供能比均为42%,n-6/n-3 PUFA构成比分别为1∶1、5∶1、10∶1、20∶1)。喂养12周后检测大鼠血糖和血脂(0、4、8和12周)、血清抗氧化指标(0和12周)以及睾周脂肪组织脂联素mRNA、蛋白表达和血清脂联素水平(12周)。结果大鼠各指标初始值组间差异均无统计学意义(P>0.05)。12周时,n-6/n-3PUFA 10∶1、20∶1组血糖显著高于对照组(P<0.05),4个高脂组血清总胆固醇(total cholesterol,TC)、甘油三酯(triglyceride,TG)显著高于对照组(P<0.01),其中20∶1组TG显著高于其余3组(P<0.01);4个高脂组谷胱甘肽过氧化物酶和超氧化物歧化酶含量显著低于对照组(P<0.05),其中20∶1组下降最明显,丙二醛含量显著高于对照组(P<0.05),其中10∶1组上升最明显;20∶1组脂联素mRNA表达显著低于对照组、1∶1组和5∶1组(P<0.05),5∶1组脂联素蛋白表达水平显著高于其余高脂组(P<0.05),而20∶1组表达水平最低(P<0.05)。结论较低的n-6/n-3 PUFA构成比(1∶1和5∶1),有助于改善高脂饲料条件下大鼠糖脂代谢及抗氧化能力,提高脂联素表达。     

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.     

Effect of altering dietary n-6:n-3 PUFA ratio on cardiovascular risk measures in patients treated with statins: a pilot study

Increasing dietary n-3 PUFA decreases the risk of CHD. Since n-6 PUFA compete with n-3 PUFA for common metabolic enzymes, the n-6:n-3 ratio intake rather than the n-3 PUFA intake levels per se may be critical. We aimed to examine whether altering the n-6:n-3 ratio affects cardiovascular risk factors in hypercholesterolaemic patients on lipid management with statins. Adhering to a randomised, crossover study design, patients on statins (n 11) were placed on one of two dietary interventions (Diet high-ratio (HR) - n-6:n-3?=?30:1 or Diet low-ratio (LR) - n-6:n-3?=?1·7:1) for 4 weeks followed after an 8-week washout period by the alternate diet. Foods enriched with n-3 or n-6 PUFA were delivered to each patient, who were given clear guidance on consumption expectations for the study. Measures of lipid profile, blood pressure and vascular function were determined. Diet LR significantly reduced body weight, LDL-cholesterol, high-sensitivity C-reactive protein, blood pressure and the apoA-1:apoB ratio. While Diet HR trended towards a similar cardioprotective profile, most of the parameters examined did not reach statistical significance. A direct comparison between diets demonstrated no significant superiority of Diet LR over Diet HR. These results suggest that a dietary intervention focused on n-6 and n-3 fatty acids may improve cardiovascular risk factors in patients over and above standard lipid management, but there is no significant advantage of a low n-6:n-3 ratio diet when compared to a high-ratio diet.     

Dietary supplementation with conjugated linoleic acid plus n-3 polyunsaturated fatty acid increases food intake and brown adipose tissue in rats

The effect of supplementation with 1% conjugated linoleic acid and 1% n-3 long chain polyunsaturated fatty acids (CLA/n-3) was assessed in rats. Food intake increased with no difference in body weights. White adipose tissue weights were reduced whereas brown adipose tissue and uncoupling protein-1 expression were increased. Plasma adiponectin, triglyceride and cholesterol levels were reduced while leptin, ghrelin and liver weight and lipid content were unchanged. Hypothalamic gene expression measurements revealed increased expression of orexigenic and decreased expression of anorexigenic signals. Thus, CLA/n-3 increases food intake without affecting body weight potentially through increasing BAT size and up-regulating UCP-1 in rats.     

广州成人膳食n-6/n-3脂肪酸比值与心血管疾病危险因素的关系

目的分析广州40～65岁居民膳食n-6/n-3脂肪酸比值与心血管疾病危险因素的关系。方法 40～65岁广州市民1133人,采用定量食物频数问卷调查对象的每日摄入食物种类和数量,计算能量和营养素摄入量,检测其红细胞膜脂肪酸构成、血脂及颈动脉内中膜厚度(IMT),分析n-6/n-3比值大小高Q3,中Q2,低Q1与血压、血脂和IMT的关系。结果 995人资料完整纳入分析。对象日均膳食总能量摄入为9.10±2.09MJ、脂肪供能比为(34.3±7.9)%。膳食n-6/n-3脂肪酸比值为(29.74±22.71):1,红细胞膜n-6/n-3脂肪酸比值为(2.7±1.0):1,膳食SFA:MUFA:PUFA为1:1.5:1。膳食n-3脂肪酸摄入量与红细胞膜n-3构成比、膳食n-6/n-3比值与红细胞膜n-6/n-3比值均呈显著正相关关系。膳食n-6/n-3比值最高组Q3(>31.16)对象的收缩压、TC和IMT水平显著高于最低组Q1(<17.40);红细胞膜n-6/n-3比值最高组Q3(>3.04)和中间组Q2(2.18～3.03)对象的收缩压、舒张压、TC、LDL-C及IMT水平均显著高于最低组Q1(≤2.17)。结论广州市40～65岁居民膳食n-6/n-3脂肪酸比值约为30:1;该比值小于17.40:1时,有较低的血压,总胆固醇及IMT水平。     

Modulation of essential (n-6):(n-3) fatty acid ratios alters fatty acid status but not bone mass in piglets

Dietary (n-6) and (n-3) fatty acids have been implicated as important regulators of bone metabolism. The main objective of this research was to define the response of whole-body growth, fatty acid status and bone mass to a reduced dietary (n-6):(n-3) fatty acid ratio. A secondary objective was to determine whether there is an amount of fat x fatty acid ratio interaction for these outcomes. Piglets (n = 32) were randomized to 1 of 4 diets: group 1: [30 g fat/L + (n-6):(n-3) ratio 4.5:1]; group 2: [30 g fat/L + (n-6):(n-3) ratio 9.0:1]; group 3: [60 g fat/L + (n-6):(n-3) ratio 4.5:1]; and group 4: [60 g fat/L + (n-6):(n-3) ratio 9.0:1]. After 21 d, outcomes assessed included growth, fatty acid status and bone mass and metabolism. Growth and bone mass did not differ among the four groups nor did arachidonic acid (AA as g/100 g fatty acids) in plasma, adipose and brain. Piglets fed diets 1 and 3 with the lower (n-6):(n-3) ratio had lower liver AA (P < 0.001). Those fed diets 1 and 2 containing 30 g fat/L had lower docosahexaenoic acid (DHA as g/100 g fatty acids) in liver (P < 0.001), plasma (P = 0.019) and adipose tissue (P = 0.045). However, piglets fed diets 1 and 3 had higher (P < 0.001) brain DHA than those fed diets with a higher (n-6):(n-3) ratio. Higher plasma DHA was associated with less bone resorption (r = -0.44, P = 0.01). Therefore, elevation of dietary (n-3) fatty acids supports growth and fatty acid status while not compromising bone mass. The results may be of relevance to the nutritional management of preterm infants whose DHA status is often too low and bone resorption too high.     

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。     

Formation of 8,11,14-octadecatrienoic acid (18:3 n-4) from naturally occurring unique fatty acid, 9,12-hexadecadienoic acid (16:2 n-4), in animal cell cultures.

9,12-Hexadecadienoic acid (16:2 n-4), present in small amounts in fish oils as a naturally occurring unique fatty acid, was incorporated into the phospholipids in rat liver BRL-3A cells to a similar extent as linoleic acid (18:2 n-6). 11,14-Octadecadienoic acid (18:2 n-4) and 8,11,14-octadecatrienoic acid (18:3 n-4) were detected in the cellular lipids of BRL-3A cells when incubated in a medium supplemented with 16:2 n-4 methyl ester. The cellular levels of these acids increased in parallel with 16:2 n-4 methyl ester added to the medium. These compounds were probably formed through conversion from 16:2 n-4 to 16:3 n-4 by delta 6 desaturation, and then 18:3 n-4 was produced by elongation, and part of the surplus 16:2 n-4, not desaturated to 16:3 n-4, elongated to 18:2 n-4. These results suggested that 16:2 n-4 was desaturated by delta 6 desaturase in vitro. It was also shown that 16:2 n-4 inhibited arachidonic acid synthesis from exogenous linoleic acid in BRL-3A cells as efficiently as alpha-linolenic acid (18:3 n-3).     

不同n-3/n-6多不饱和脂肪酸构成比膳食对大鼠一磷酸腺苷活化蛋白激酶表达的影响

目的研究不同n-3/n-6配比脂肪酸对大鼠磷酸腺苷酸活化蛋白激酶(AMP-activated protein kinase,AMPK)蛋白及活性表达的影响。方法58只SD大鼠适应性喂养7d后,尾静脉取血。根据血清总胆固醇水平随机分为:空白(基础饲料);高脂(高脂饲料);高脂1:1(高脂饲料+n-3/n-6=1:1配方油);高脂1:5(高脂饲料+n3/n6=1:5配方油);低脂1:1(脱脂基础饲料+n-3/n-6=1:1配方油);低脂1:5(脱脂基础饲料+n3/n6=1:5配方油)6组,喂养45d,观察大鼠摄食与体重增长。于实验前1d,15d,30d,45d分别各取血测血清总胆固醇水平,于D45处死动物。Western blotting分别分析肝和下丘脑组织中AMPK-α总蛋白及其活性表达。结果添加PUFA的4个比例组血清TC、体重与高脂组相比,显著降低,且低脂2个比例组和高脂1:1组均与高脂1:5组相比有显著差异。添加PUFA的4个比例组均与高脂组相比,大鼠下丘脑AMPK-α总蛋白表达水平明显降低,肝AMPK-α蛋白表达水平均比高脂组明显升高。结论PUFA改善血脂可能是通过增加肝AMPK表达,抑制下丘脑AMPK表达,增加肝脂肪酸氧化和抑制食欲,影响血脂代谢。     

Lack of effect of dietary n-6:n-3 PUFA ratio on plasma lipids and markers of insulin responses in Indian Asians living in the UK

Summary Background Indian Asians living in Western Countries have an over 50 % increased risk of coronary heart disease (CHD) relative to their Caucasians counterparts. The atherogenic lipoprotein phenotype (ALP), which is more prevalent in this ethnic group, may in part explain the increased risk. A low dietary long chain n-3 fatty acid (LC n-3 PUFA) intake and a high dietary n-6 PUFA intake and n-6:n-3 PUFA ratio in Indian Asians have been proposed as contributors to the increased ALP incidence and CHD risk in this subgroup. Aim To examine the impact of dietary n-6:n-3 PUFA ratio on membrane fatty acid composition, blood lipid levels and markers of insulin sensitivity in Indian Asians living in the UK. Methods Twentynine males were assigned to either a moderate or high n-6:n-3 PUFA (9 or 16) diet for 6 weeks. Fasting blood samples were collected at baseline and 6 weeks for analysis of triglycerides, total-, LDL- and HDL-cholesterol, non-esterified fatty acids, glucose, insulin, markers of insulin sensitivity and C-reactive protein. Results Group mean saturated fatty acid, MUFA, n-6 PUFA and n-3 PUFA on the moderate and high n-6:n-3 PUFA diets were 26 g/d, 43 g/d, 15 g/d, 2 g/d and 25 g/d, 25 g/d, 28 g/d, 2 g/d respectively. A significantly lower total membrane n-3 PUFA and a trend towards lower EPA and DHA levels were observed following the high n-6:n-3 PUFA diet. However no significant effect of treatment on plasma lipids was evident. There was a trend towards a loss of insulin sensitivity on the high n-6:n- 3 PUFA diet, with the increase in fasting insulin (P = 0.04) and HOMA IR [(insulin x glucose)/ 22.5] (P = 0.02) reaching significance. Conclusion The results of the current study suggest that, within the context of a western diet, it is unlikely that dietary n-6:n-3 PUFA ratio has any major impact on the levels of LC n-3 PUFA in membrane phospholipids or have any major clinically relevant impact on insulin sensitivity and its associated dyslipidaemia. Source of support: This project was funded by the Food Standards Agency (FSA), UK.     

Response of tissue phospholipid fatty acid composition to dietary (n-6) and replacement with marine (n-3) and saturated fatty acids in the rat

Nine groups of weanling male rats were maintained for ten weeks on a fat-free semi-synthetic diet supplemented with 10% by weight of oil, composed wholly of gamma-linolenic acid-rich evening primrose oil, or replaced partly or completely (25%, 50%, 75%, and 100%) by marine or hydrogenated coconut oils. Plasma phospholipid content and phospholipid fatty acid composition of plasma, red blood cells, liver, kidney, and heart were determined. Replacement of marine oil as 2.5% of the diet caused a decrease of plasma phospholipid concentration to 60%, with no furthur decrease at higher proportions. Except in the heart, marine oil in combination with evening primrose oil caused an increase in 20:3(n-6) concentration, and a decrease in 20:4(n-6) levels in all tissues examined. The ratio 20:3(n-6)/20:4(n-6) increased with increasing marine oil supplementation to the diet, but not when marine oil was the sole source of dietary fatty acids (10%). Replacement of hydrogenated coconut oil did not affect 20:3(n-6) concentrations. A decrease in 20:4(n-6) was observed when hydrogenated coconut oil was supplemented to the diet at 10%, causing a state of EFA deficiency as shown by the elevation of 20:3(n-9). There was an increase in 20:5(n-3) and 22:6(n-3) with increased marine oil intake. The ratio 20:3(n-6)/20:4(n-6) correlated significantly with 20:5(n-3), but not with 22:6(n-3), in all tissues except the heart, suggesting an inhibitory effect of 20:5(n-3) on delta-5-desaturase enzyme.     

Low n-6:n-3 fatty acid ratio,with fish- or flaxseed oil,in a high fat diet improves plasma lipids and beneficially alters tissue fatty acid composition in mice

BACKGROUND: Health benefits from low n-6:n-3 fatty acid (FA) ratio on cardiovascular risk have been shown. However, the impact of the source of n-3 FAs has not been fully investigated. AIM: Our purpose was to investigate cardiovascular benefits of oils with a low ratio of n-6:n-3 FAs, but different sources of n-3 FAs in C57BL/6 mice. METHODS: Twenty-one mice were divided into 3 groups (n=7) and fed a diet supplemented with either a fish or flaxseed oil-based 'designer oils' with an approximate n-6:n-3 FA ratio of 2/1 or with a safflower-oil-based diet with a ratio of 25/1, for 16 weeks. Plasma lipids and fatty acid profile of the liver tissue were characterized. RESULTS: Compared to baseline, plasma triacylglycerol levels declined (>50%) in all groups by week 4. Plasma cholesterol levels were reduced in both fish and flax groups by 27% and 36%, respectively, as compared to controls at endpoint. The levels of EPA and DHA in liver phospholipids were significantly increased in both fish and flax groups as compared to the control group, with more profound increases in the fish group. Arachidonic acid levels were similarly decreased in the liver tissues from both fish and flax groups as compared to controls. CONCLUSIONS: Our data suggest that health benefits may be achieved by lowering dietary n-6:n-3 FA even in a high fat diet medium.     

Dietary supplementation with oils rich in (n-3) and (n-6) fatty acids influences in vivo levels of epidermal lipoxygenase products in guinea pigs

Certain dietary oils may have therapeutic potential in the treatment of inflammatory skin disorders. Presumably, the fatty acid constituents of these dietary oils exert their effects by altering the levels of cutaneous eicosanoids. Prompted by this possibility, we investigated whether supplementation of guinea pig diets with fish oil [rich in 20:5(n-3)] or borage oil [rich in 18:3(n-6)] could significantly alter epidermal levels of eicosanoids compared with control animals supplemented with olive oil. After feeding periods of 4, 8 or 12 wk, the epidermis from the animals was analyzed for: 1) fatty acid composition of individual epidermal phospholipids, 2) levels of lipoxygenase products, and 3) levels of cyclooxygenase products (prostaglandins). Our results demonstrated that the animals supplemented with dietary fish oil had elevated levels of 20:5(n-3) in epidermal phospholipids and elevated epidermal levels of 15-hydroxyeicosapentaenoic acid (15-HEPE) [the 15-lipoxygenase product of 20:5(n-3)] compared with guinea pigs fed olive oil or borage oil. Similarly, the animals supplemented with dietary borage oil had elevated levels of 20:3(n-6) [the epidermal elongase product of 18:3(n-6)] in epidermal phospholipids and elevated epidermal levels of 15-hydroxyeicosatrienoic acid [15-HETrE, the epidermal 15-lipoxygenase product of 20:3(n-6)] compared with guinea pigs fed olive oil or fish body oil. There were no significant changes in epidermal levels of prostaglandins. Both 15-HEPE and 15-HETrE have been identified as possible anti-inflammatory metabolites, and their elevated presence in the epidermis of animals fed oils rich in 20:5(n-3) or 18:3(n-6) may provide a mechanism for the beneficial effects of these oils on inflammatory conditions.     

Leptin and phospholipid-esterified docosahexaenoic acid concentrations in plasma of women: observations during pregnancy and lactation

BACKGROUND: The n-3 fatty acid status changes during pregnancy and lactation. Plasma leptin concentrations and gene expression have been related to n-3 fatty acids. OBJECTIVE: To investigate the relation between plasma leptin concentration and the docosahexaenoic acid (22:6n-3) content of plasma phospholipids during early pregnancy and the postpartum period. DESIGN: Leptin (radioimmunoassay) and the phospholipid fatty acid profile (capillary gas-liquid chromatography) were measured in plasma of women during two independent longitudinal observational studies. Dietary intake of n-3 fatty acids was also determined. RESULTS: Within the first 10 weeks after the last menstrual period, an almost parallel increase in leptin concentration and the 22:6n-3 content (mg/l and % wt/wt) of plasma phospholipids was seen (study 1, n = 21). During the postpartum period (study 2, n = 57), leptin levels decreased quickly, preceding the changes in 22:6n-3 concentrations. During both studies, leptin concentrations did not consistently relate to dietary intake of n-3 fatty acids or to 22:6n-3 concentrations in plasma phospholipids. Before and during early pregnancy (study 1), significant positive associations between leptin levels and the total amount of phospholipid-associated fatty acids were found. No such association was seen during late pregnancy or the postpartum period (study 2). The postpartum decrease in leptin levels did not differ between lactating and non-lactating women. CONCLUSIONS: Not the 22:6n-3 content, but the total amount of phospholipid-associated fatty acids was related to plasma leptin concentration, before and during early pregnancy but not during late pregnancy and the postpartum period.     

膳食n-6/n-3脂肪酸比值对小鼠淋巴细胞脂肪酸构成和功能的影响

目的观察膳食n6n3脂肪酸比值对淋巴细胞脂肪酸构成及细胞功能的影响。方法BALBc小鼠随机分为5组n6n3比值分别为1(A组)、75(B组)、15(C组)、30(D组)和正常对照组,其中实验组S∶M∶P模拟中国居民膳食脂肪酸摄入的S∶M∶P为1∶15∶1,正常对照组为AIN93G配方的1∶15∶37。基础饲料采用AIN93G配方,脂肪酸构成以食用油脂调配。饲养12周。测定小鼠T淋巴细胞功能,脾淋巴细胞脂肪酸构成、PGE2水平。结果n6n3比值接近1时,小鼠T淋巴细胞增殖活性、CD4+、CD8+T细胞比例、培养上清IL2、PGE2水平显著降低;淋巴细胞C18∶2、C20∶4、n6PUFA含量显著减少;C22∶6、C16∶1、C18∶1、总MUFA含量明显高于其他实验组。淋巴细胞C22∶6含量与淋巴细胞增殖活性显著负相关;C20∶5含量与CD4+T淋巴细胞比例、IL2水平显著负相关;C16∶1含量与CD4+、CD8+T淋巴细胞比例显著负相关。结论小鼠脾淋巴细胞的脂肪酸构成受膳食脂肪酸构成的影响;n6n3比值为1组与比值为30的膳食组相比较,小鼠T淋巴细胞增殖活性受到抑制。