孕乳期补充鱼油对大鼠行为发育的影响

目的：探讨孕、乳期补充富含DHA鱼油对大鼠行为发育的影响。方法：以出生前,后脑发育关键期大鼠为研究对象,设1个对照组和添加鱼油的3个剂量组（其中DHA的量分别为0.7、5、15.0、30.0g/kg饲料）,喂养期限为孕0日至仔鼠45日龄。观察妊娠、分娩一般指标,进行断乳前行为发育评价、幼鼠学习行为测试等。结果：与对照组相比,DHA15.0 g/kg饲料组新生鼠脑重显著增加（P＜0.05）;2项新生反射指标平面翻正、视觉定向发育显著提前（P＜0.05）;跳台潜伏期延长,错误次数减少和避暗潜伏期延长（P＜0.05）。结论：孕、乳期补充一定剂量的DHA,可对子代大鼠神经发育产生有益影响;孕、乳期补充DHA的较适剂量为15.0g/kg饲料。     

发育期补充DHA对大鼠学习记忆的影响

目的：探讨发育期补充DHA对大鼠学习记忆的影响。方法：以出生前后脑发育关键期大鼠为研究对象,设一个对照组和添加DHA的3个剂量组（添加DHA的量分别为0、7．5、15、30g/kg饲料）,喂养期限为妊娠第一日至仔鼠45日龄。选用跳台法和避暗法,进行幼鼠学习行为测试,并同步测定幼鼠海马内单胺类神经递质5－HTT、NE、DA和肽类神经递质生长抑素（SS）的含量。结果：与对照组相比,15g/kg、30g/kg饲料组幼鼠跳台潜伏期延长,错误次数减少,避暗潜伏期延长,且15g/kg组最显（P＜0．05）;补充DHA的各剂量组海马内5－HT、DA、SS含量均显高于对照组（P＜0．05）。结论：（1）发育期补充一定剂量的DHA,可增强大鼠学习记忆能力,较适剂量为15g/kg饲料;（2）DEIA增强学习记忆可能与海马内5－HT、DA、SS量增高有关,且存在其它递质或递质外系统的复杂调控。     

二十二碳六烯酸对1-溴丙烷致大鼠学习能力损伤的拮抗作用

目的 观察二十二碳六烯酸(DHA)对1-溴丙烷(1-BP)致大鼠学习能力损伤的拮抗作用.方法 将48只健康成年SPF级雄性Wistar大鼠随机分为4组,即对照(玉米油)组、1-BP染毒组和低、高剂量DHA干预组,每组12只.1-BP染毒组和低、高剂量DHA干预组每天灌胃染毒800 mg/kg的1-BP;4 h后,低、高剂量DHA干预组分别灌胃染毒250、500mg/kg的DHA,每日1次,连续11d.染毒第8～11天采用Morris水迷宫试验中的定位导航试验检测大鼠的学习能力.染毒结束后,检测大脑皮层匀浆中还原型谷胱甘肽(GSH)、丙二醛(MDA)含量及谷胱甘肽还原酶(GR)活力.采用Westernblotting方法检测大脑皮层脑红蛋白(neuroglobin,Ngb)的表达.结果 与对照组比较,1-BP染毒组大鼠游泳总路程和逃避潜伏期延长(P＜0.05);与1-BP染毒组相比,各剂量DHA干预组大鼠的游泳路程和逃避潜伏期缩短(P＜0.05).与对照组比较,1-BP染毒组大鼠大脑皮层匀浆中GSH含量及GR活力均下降,而1-BP染毒组MDA含量及高剂量DHA干预组GSH含量均升高(P＜0.05);与1-BP染毒组比较,各剂量DHA干预组大鼠大脑皮层匀浆中GSH含量及GR活力均升高,MDA含量均下降(P＜0.05).与对照组比较,1-BP染毒组和低剂量DHA干预组大鼠大脑皮层匀浆中Ngb蛋白的表达水平均下降,而高剂量DHA干预组Ngb蛋白的表达水平升高(P＜0.05);与1-BP染毒组比较,各剂量DHA干预组大鼠大脑皮层匀浆中Ngb蛋白的表达水平均升高(P＜0.05).结论 DHA能够减轻1-BP导致的大鼠中枢神经系统氧化应激反应及由此引起的学习能力损伤,激活GR活力、增强Ngb表达可能是DHA的保护机制之一.     

高含量DHA/EPA甘油三酯鱼油改善脂肪肝大鼠脂质代谢作用的研究

目的 探讨高含量DHA/EPA甘油三酯(TG)鱼油对脂肪肝模型大鼠脂质代谢的改善作用及机制.方法 采用在饲料中添加1％乳清酸的方法建立脂肪肝大鼠模型.将大鼠分为乙酯鱼油对照组、低含量DHA/EPA-TG鱼油对照组和高含量DHA/EPA-TG鱼油低、中、高剂量组,每组10只.分别灌胃不同结构形式的鱼油20d后,检测大鼠血清脂质和肝脏脂质含量;采用RT-PCR法测定肝脏中固醇调节元件结合蛋白-1c (SREBP-1c)和过氧化物酶体增殖物激活受体(PPAR-α)等脂质代谢调控因子mRNA表达和脂肪酸合成酶(FAS)、苹果酸酶(ME)、葡萄糖6磷酸脱氢酶(G6PDH)等脂肪合成相关酶以及肉碱棕榈酰转移酶(CPT-1)等脂肪分解相关酶mRNA表达量.结果 高含量DHA/EPA-TG鱼油可显著降低血清和肝脏脂质水平(P＜0.05,P＜0.01),明显抑制SREBP-1c、FSA、ME、G6PDH等脂肪合成相关基因mRNA表达(P＜0.01),有效上调PPAR-α、CPT-1 (P＜0.05,P＜0.01)等脂肪分解相关基因mRNA表达,且作用效果为三种鱼油中最优.结论 高含量DHA/EPA-TG鱼油可明显改善脂肪肝大鼠脂质代谢,其机制与下调脂肪酸合成相关基因表达,促进脂肪酸分解相关基因表达有关.     

急性酒精摄入对大鼠记忆功能的影H向及海马内p-CREB的变化

[目的]研究急性酒精摄入对大鼠记忆功能的影响,及海马内cAMP反应元件结合蛋白(CREB)磷酸化水平的变化.[方法]采用Morris水迷宫方法检测急性摄入1 g/kg、2 g/kg和3g/kg剂量的酒精,以及摄入3 g/kg酒精0.5、1、2、4 h后成年雄性SD大鼠记忆功能的变化,采用Western Blot方法检测急性摄入3 g/kg后大鼠海马中CREB磷酸化(p-CREB)水平随时间的变化.[结果]Morris水迷宫检测结果显示,随酒精摄入剂量增加,潜伏期及游泳路程均呈延长趋势,其中2 g/kg组和3 g/kg组与对照组比较差异有统计学意义(P＜0.05);急性摄入3 g/kg酒精0.5、1及2 h后,潜伏期及游泳路程明显延长(P＜0.05),其中2 h最高.4 h恢复.Westem Blot结果显示急性摄入3 g/kg酒精后0.5、1及2 h CREB磷酸化水平逐渐升高,2 h达到最高,4 h降至正常水平.[结论]急性摄入酒精引起记忆功能改变存在量效、时效规律.大鼠海马中CREB磷酸化水平变化与其相一致,提示酒精可能通过引起海马内记忆功能相关蛋白CREB磷酸化水平升高引起记忆功能的改变.     

鱼油对小鼠学习记忆的影响

用5％鱼油饲料喂眼养离乳小鼠和离乳后3周小鼠1个月，观察鱼油对小鼠学习记忆能力的影响。结果显示；鱼油可使离乳小鼠的跳台实验潜伏期延长，错误数减少，避暗实验潜伏期延长，水迷宫游出时间缩短，说明鱼油对离乳小鼠学习记忆能力有促进作用。而对离乳3周小鼠的学习记忆能力的影响不明显，仅显示避暗实验潜伏期延长。本文提示：在幼年期补充鱼油效果较好。     

注射用环磷酰胺对大鼠致畸敏感期毒性研究

目的 观察环磷酰胺1次染毒或连续染毒对大鼠致畸敏感期的毒性反应.方法 选用SD大鼠,设对照组(生理氯化钠)、7.0、15.0 mg/kg染毒组,每组6只孕鼠.15.0 mg/kg组于孕第12天1次皮下注射染毒;7 mg/kg组于孕第11～13天连续皮下注射染毒3次.观察孕鼠体质量及一般健康状况,于妊娠第20天解剖并记录子宫连仔鼠质量、胎盘质量、仔鼠体质量、黄体数、死仔和活仔鼠数、仔鼠身长和尾长;检查仔鼠外观、骨骼和内脏.结果 ①2个染毒组的孕鼠染毒后均很快出现毒性反应,精神状态明显变差、活动减少、体质量减轻;②7.0和15.0 mg/kg染毒组死仔率分别为60.29%和18.37%,明显高于对照组的1.69%(P＜0.05);子宫连仔质量、胎盘质量、鼠仔体质量、身长、尾长均明显低于对照组(P＜0.05);③染毒组存活仔鼠普遍发生脑膜膨出,骨骼骨化不全,15.0 mg/kg组仔鼠大多数出现并趾、少趾、足外翻、短肋、缺肋等异常.结论 大鼠致畸敏感期1次(15.0 mg/kg)或连续3次(7.0 mg/kg)皮下注射环磷酰胺,均可导致明显的胚胎毒性反应,毒性反应的严重程度与染毒时间和剂量密切相关.     

吡啶酸铬对肥胖大鼠体重及其脂质代谢的影响

目的探讨吡啶酸铬对肥胖大鼠体重、体脂含量及其血脂等水平的影响.方法以高脂饲料诱导大鼠肥胖模型,然后将肥胖模型鼠随机分为4组:对照组、150μg/kg体重组、300μg/kg体重组和600 μg/kg体重组三个吡啶酸铬组,共6周.观察大鼠体重、睾丸 肾脂肪垫重量、血脂、血糖(GLU)、胰岛素(INS)及血瘦素(Leptin)水平的变化.结果300μg/kg与600μg/kg剂量组的动物体重、睾丸 肾脂肪垫、及Leptin水平均显著低于对照组(P＜0.05);三个吡啶酸铬组的TC与TG显著低于对照组(P＜0.05);600μg/kg组的脂体比及INS低于对照组(P＜0.05),而高密度脂蛋白胆固醇(HDL-C)则显著高于对照组(P＜0.05);各组间的血糖水平差异不明显.结论吡啶酸铬有改善大鼠肥胖及降低高血脂水平的作用.     

多烯鱼油对高脂模型大鼠血脂水平影响的研究

[目的]研究多烯鱼油对大鼠血脂水平的影响。[方法]将雄性大鼠按血清总胆固醇（TC）水平随机分为对照组、低、中、高剂量组,喂饲高脂饲料,同时给与不同剂量的多烯鱼油灌胃45 d,结束时测TC、甘油三脂（TG）、高密度脂蛋白胆固醇（HDL-C）水平。[结果]多烯鱼油0.333 g/kg.BW和1.00 g/kg.BW剂量组可使大鼠血清TC、TG值降低,差异有统计学意义（P〈0.05）。[结论]多烯鱼油具有降血脂的作用。     

鱼油补充对中老年人血清多不饱和脂肪酸构成脂联素水平及抗氧化能力影响的随机对照研究

目的探讨不同剂量鱼油补充对中老年人血清多不饱和脂肪酸(PUFA)构成、脂联素水平及抗氧化能力的影响。方法以240名45~70岁中老年人为对象,随机分成对照组(不服鱼油),鱼油低、中、高剂量组[分别每日服1、2、4粒鱼油胶囊(每粒含182mg EPA+129mg DHA)]4组,干预12w,干预前后进行问卷调查、体格测量并采集空腹静脉血。测定血清脂肪酸、脂联素、血糖、丙二醛(MDA)、总超氧化物歧化酶(SOD)及谷胱甘肽过氧化物酶(GSH-Px)含量。结果 201人完成试验。干预前对象的基线资料及血清学指标组间无差异;干预后对照组各指标无明显变化,鱼油各组血清二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)及n-3 PUFA显著上升,高于对照组(P0.05),n-6/n-3PUFA则均低于对照组(P0.05);干预后鱼油中、高剂量组血清脂联素显著上升,血糖显著下降,与对照组相比有统计学差异(P0.05);血清MDA明显下降;各鱼油组总SOD及GSH-Px含量显著上升,中剂量组的GSH-Px及高剂量组的总SOD、GSH-Px均高于对照组(P0.05)。结论一定剂量鱼油补充可显著升高中老年人血清EPA、DHA、脂联素、总SOD及GSH-Px水平并降低n-6/n-3PUFA、血糖及MDA含量,以高剂量组(1.24g/d)最为明显。     

Maternal DHA Supplementation during Pregnancy and Lactation in the Rat Protects the Offspring against High-Calorie Diet-Induced Hepatic Steatosis

Maternal supplementation during pregnancy with docosahexaenoic acid (DHA) is internationally recommended to avoid postpartum maternal depression in the mother and improve cognitive and neurological outcomes in the offspring. This study was aimed at determining whether this nutritional intervention, in the rat, protects the offspring against the development of obesity and its associated metabolic disorders. Pregnant Wistar rats received an extract of fish oil enriched in DHA or saline (SAL) as placebo by mouth from the beginning of gestation to the end of lactation. At weaning, pups were fed standard chow or a free-choice, high-fat, high-sugar (fc-HFHS) diet. Compared to animals fed standard chow, rats exposed to the fc-HFHS diet exhibited increased body weight, liver weight, body fat and leptin in serum independently of saline or DHA maternal supplementation. Nevertheless, maternal DHA supplementation prevented both the glucose intolerance and the rise in serum insulin resulting from consumption of the fc-HFHS diet. In addition, animals from the DHA-fc-HFHS diet group showed decreased hepatic triglyceride accumulation compared to SAL-fc-HFHS rats. The beneficial effects on glucose homeostasis declined with age in male rats. Yet, the preventive action against hepatic steatosis was still present in 6-month-old animals of both sexes and was associated with decreased hepatic expression of lipogenic genes. The results of the present work show that maternal DHA supplementation during pregnancy programs a healthy phenotype into the offspring that was protective against the deleterious effects of an obesogenic diet.     

Low arachidonic acid rather than alpha-tocopherol is responsible for the delayed postnatal development in offspring of rats fed fish oil instead of olive oil during pregnancy and lactation

This study was designed to compare in rats the effects of dietary fish oil and olive oil during pregnancy and lactation on offspring development, fatty acid profile and vitamin E concentration. From d 0 of pregnancy, female Sprague-Dawley rats were divided into two groups that were fed purified diets that differed only in their nonvitamin lipid components. One diet contained 10 g fish oil/100 g diet (FOD), whereas the other contained 10 g olive oil/100 g diet (OOD). At d 20 of gestation, maternal adipose tissue fatty acid profile did not differ between rats fed the two diets, whereas both maternal and fetal plasma and liver arachidonic acid (AA) contents were proportionally lower and eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid contents were higher in the FOD group than in the OOD group. alpha-Tocopherol concentration was lower in maternal and fetal plasma, liver and brain in the FOD group than in the OOD group. The postnatal increase in body weight and length was less and body and psychomotor maturation indices were delayed in pups from FOD-fed dams compared with those from OOD-fed dams. This difference was maintained when pups were cross-fostered at birth, with the delay in postnatal development present in the pups suckling dams fed FOD during lactation. At age 21 d, pups suckling dams fed FOD had lower AA and higher EPA and DHA concentrations in brain phospholipids. Although alpha-tocopherol in plasma and liver was lower in pups suckling dams fed FOD rather than OOD, brain alpha-tocopherol concentrations did not differ. Milk yield and milk alpha-tocopherol and AA concentrations were lower and EPA and DHA were higher in the milk of dams fed FOD compared with those fed OOD. Postnatal development indices and the proportion of plasma, liver and brain AA concentrations, although not plasma, liver and brain alpha-tocopherol concentrations, recovered to the values found in dams fed OOD when the FOD was supplemented with gamma-linolenic acid. However, postnatal development indices were not recovered when the FOD was supplemented with sufficient exogenous vitamin E to increase plasma and liver alpha-tocopherol concentrations above those in dams fed OOD. Thus, although feeding FOD during pregnancy and lactation decreases both alpha-tocopherol and AA concentrations, the latter deficiency rather than the former seems to be responsible for delayed postnatal development of rat pups.     

Auditory Brainstem Evoked Response in Juvenile Rats Fed Rat Milk Formulas with High Docosahexaenoic Acid

Abstract

Previous studies found that juvenile offspring of rats fed high docosahexaenoic acid (DHA; 22:6n-3) diets through gestation and lactation had longer auditory brainstem-evoked response (ABR) accompanied by higher 22:6n-3 and lower arachidonic acid (ARA; 20:4n-6) in brain. In the present study, ABR was assessed in juvenile rats fed high-DHA diets only postnatally.

Methods: Rat pups were fed rat milk formulas with varying amounts of DHA and ARA to 19 days of age followed by diets with the corresponding fatty acids. The high-DHA group was fed 2.3% of fatty acids as DHA, the DHA+ARA group was fed DHA and ARA at 0.6 and 0.4% of fatty acids, levels similar to those in some infant formulas, and the unsupplemented group was fed no DHA or ARA. ABR and fatty acid and monoamine levels in brain were measured on postnatal days 26-28. Statistical analyses were measured by ANOVA.

Results: ARA and DHA levels in brain increased with supplementation. ABR was shorter in the high-DHA group than the DHA+ARA group and not different from the unsupplemented or dam-reared suckling group. Norepinephrine levels in the inferior colliculus were lower in the high-DHA group than the DHA+ARA group and higher in all formula groups compared to the dam-reared group.

Conclusion: In contrast to the longer ABR in juvenile offspring of rats fed high-DHA through gestation and lactation, ABR was shorter in juvenile rats fed high-DHA diets only after birth than rats fed ARA+DHA. Further studies are needed to understand the relationship between dietary DHA, norepinephrine, and auditory system development over a range of DHA intakes and discrete periods of development.     

Maternal and early dietary fatty acid intake: changes in lipid metabolism and liver enzymes in adult rats

Over the last decade, much evidence has emerged to suggest that alterations in maternal nutrition during pregnancy may irreversibly affect aspects of physiological and biochemical functions in the fetus. This study was designed to determine the mechanisms involved in these alterations. Our hypothesis was that the type of maternal dietary fat received in early life could determine the level of lipoprotein lipase (LPL; EC 3.1.1.34) activity and gene expression which would be maintained into later life. A diet high in (n-3) polyunsaturated fatty acids was predicted to be associated with higher levels of lipoprotein lipase (LPL) activity and expression and lower levels of plasma triglyceride after a high fat meal challenge. Using a 2x2 factorial design, Wistar Albino rats were pair-fed either a fish oil diet (50 g/kg) or a mixed oil diet (50 g/kg) for the last 2 wk of gestation, during lactation and pups were fed these diets until 5 wk of age. After 5 wk, the rats were fed nonpurified diet. The rats were killed at 5 wk (young) or 10 wk (adult) of age after a mixed oil (50 g/kg) test meal. There were significant age effects on plasma triglyceride (P<0.02), cholesterol (P<0.001), glucose-dependent insulinotrophic polypeptide (GIP) (P<0.001) and liver glutathione reductase activity (P<0.05) which were all higher in the young rats compared to the adults. There were significant effects of diet on triglyceride (P<0.001), cholesterol (P<0.001) and LPL mRNA levels (P<0.001). GIP and triglyceride levels were significantly correlated (r = 0.66; P<0.001). Omental adipose tissue LPL activity as significantly higher in the fish-oil fed groups compared to the other groups (P<0.001), whereas Epididymal adipose tissue LPL mRNA was significantly higher in the mixed oil-fed adults compared to the other groups (P<0.001). The latter result suggested an imprinting effect of fatty acid composition in early life on LPL gene expression. Liver superoxide dismutase activity was affected by age and diet and was higher in the young than in the adults and higher in the fish oil-fed young than in those fed the mixed oil-fed (P<0.005). Catalase activity was also affected by age (P<0.001) and diet (P<0.001), and there was a significant interaction between age and diet (P<0.001). Catalase activity was higher in rats fed fish oils at both stages of development, suggesting that feeding fish oils to rats in early life raises oxidative stress throughout life. The majority of the significant differences shown were between the age groups and not between the two dietary groups, suggesting that postprandial handling of a standard fat meal is affected more by age than by early dietary fatty acid composition. However, the mechanisms of biological imprinting of fatty acids on LPL expression and on enzymes related to oxidative stress requires more investigation.     

Effect of fish oil and safflower oil in common Japanese diet on human plasma fatty acid composition

The influence of fish oil and safflower oil contained in the common Japanese diet as the main dietary polyunsaturated fatty acid source on plasma fatty acids in ten female student volunteers (21-22 years old) was investigated. The subjects were divided into two groups and fed the experimental diets for five days. The total daily fat intake in the fish diet and safflower oil diet was 54.4 g and 56.2 g, respectively, and the fat derived from fish and safflower oil was 16 g and 23 g, respectively. The proportion of linoleic acid was reduced in the plasma of subjects fed the fish diet and increased in the plasma of subjects fed the safflower oil diet. The plasma levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were significantly elevated in the fish diet group. The ratio of EPA/arachidonic acid (AA) was higher, and those of n-6/n-3 and n-9/n-3 were lower in the plasma of subjects fed the fish diet when compared to the results obtained from plasma of subjects fed the safflower oil diet. From these results, it seems likely that fish oil in the common Japanese diet is a favorable source of plasma EPA and DHA even in such short term supplementation and with such a small amount of daily consumption.     

Dietary n-3 polyunsaturated fatty acids increase oxidative stress in rats with intracerebral hemorrhagic stroke

Intake of n-3 polyunsaturated fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) has been suggested to associate with an increased risk of hemorrhagic stroke. The present study was designed to investigate the hypothesis that EPA and DHA increase oxidative stress and hemorrhage volume in rats with intracerebral hemorrhagic (ICH) stroke. Thirty-five-week-old male rats were fed an American Institute of Nutrition–93M diet containing 0% (n = 27), 0.5% (n = 15), or 1% EPA + DHA of total energy for 5 weeks. Of 5 rats fed 1% EPA + DHA (41%), 5 died because of excessive bleeding within 12 hours after ICH surgery. Behavior test score and hemorrhage volume were significantly (P < .05) greater in the 1% EPA + DHA–fed rats than in other rats. Magnetic resonance imaging consistently showed that edema and bleeding were visible in only the rats fed 1% EPA + DHA. Levels of superoxide dismutase and glutathione were significantly (P < .05) lower in rats fed 0.5% and 1% EPA + DHA than those fed 0% EPA + DHA. Thiobarbituric acid–reactive substance content was significantly (P < .05) higher in 1% EPA + DHA–fed rats than in 0% and 0.5% EPA + DHA–fed rats. The level of 8-hydroxydeoxyguanosine was significantly (P < .05) higher in ICH rats with all diets than in sham surgery rats. Brain levels of EPA and DHA were highest in rats fed 1% EPA + DHA than in rats fed 0% and 0.5% EPA + DHA. These results suggested that intake of 1% EPA + DHA of total energy could lead to oxidative damage to the brain and thus increase the risk of intracerebral hemorrhagic stroke in this rat model.     

Enrichment of (n-3) fatty acids of suckling rats by maternal dietary menhaden oil

The study was undertaken to determine whether the content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in neonatal rats can be increased through milk provided by lactating mothers fed a diet containing 20% menhaden oil (experimental group), in comparison with a group fed a 20% corn oil diet (control group). The test diets were isocaloric and provided 41% of total energy as fat. Coinciding with 3-9% higher maternal body weight gain throughout the lactation period with the menhaden oil diet, the suckling rats in the experimental group at the ages of 3-9 d gained 5-10% more weight than did their control counterparts. When compared with corn oil, maternal dietary menhaden oil induced not only a higher weight percentage but also higher concentrations (microgram/mL) of EPA, DHA and total (n-3) fatty acids in milk, plasma, platelets and erythrocytes of neonates. These changes were accompanied by lower arachidonic and linoleic acid levels. EPA and DHA were detected in all three blood components of the control group, whose corn oil diet contained linolenic acid but not longer chain (n-3) fatty acids. This finding, together with the higher DHA to EPA ratios found in the three blood components than in the milk of the experimental group, suggests that neonatal rats possess the enzymes necessary for producing DHA from EPA and linolenate by desaturation and elongation mechanisms.     

Effect of dietary DHA on DHA levels in retinal rod outer segments in young versus mature rats

We compared the effect of direct supplementation with docosahexaenoic acid (DHA) on the fatty acid composition of the liver and the rod outer segment (ROS) membranes of the retina in young (five-week-old) and mature (one-year-old) rats. In young rats, a high content of DHA in the diet (9.7% of total energy) effectively increased the proportion of DHA in ROS membranes (41.8%), compared with the proportion observed in a linoleic acid (LA) diet group (control, 31.6%). The proportion of DHA was also significantly higher in the livers of young DHA-fed rats. These results show that direct supplementation with DHA is very effective in increasing DHA levels in the ROS membranes and livers of developing animals. In contrast, in mature rats there was no significant increase in the proportion of DHA in the ROS membranes, even after the highest dose (8.4% of total energy) of DHA, although the proportion of DHA was significantly higher in the livers of DHA-fed rats. The changes in fatty acid composition in the ROS membranes were different in young and mature rats fed high-DHA diets. Our findings indicate that mature rats maintain a constant level of DHA in the ROS membranes even after being directly supplemented with high doses of DHA.     

Long-chain (n-3) polyunsaturated fatty acids are more efficient than alpha-linolenic acid in improving electroretinogram responses of puppies exposed during gestation, lactation, and weaning

Long-chain PUFAs (LCPUFAs) are essential for proper neural and retinal development in many mammalian species. We investigated puppies born to dogs fed diets containing varying amounts of vegetable and marine (n-3) fatty acids during gestation/lactation. The fatty acid compositions of dogs' milk and puppy plasma phospholipids were evaluated, and electroretinographic responses of the young dogs were determined after they were weaned to the same diets. Dogs' milk fatty acid composition reflected the diets fed during gestation/lactation. The milk of dogs fed a high alpha-linolenic acid (ALA) diet was enriched in ALA but not docosahexaenoic acid (DHA). Puppies fed this ALA-enriched milk accumulated more plasma phospholipid DHA than the low (n-3) fatty acid group. However, this accumulation was less than that obtained in puppies fed preformed DHA during development and suckling (P < 0.05). Electroretinograms (ERGs) of 12-wk-old puppies revealed significantly improved visual performance in dogs fed the highest amounts of (n-3) LCPUFAs (P < 0.05). These puppies demonstrated improved rod response (improved amplitude and implicit time of the a-wave, P < 0.05). Puppies from the low (n-3) fatty acid group exhibited the poorest ERG responses compared with the high-marine or high-vegetable (n-3) groups. A novel parameter devised in this study, the initial intensity at which the a-wave was detectable (i.e., threshold intensity), also demonstrated that retinal response of puppies consuming the (n-3) LCPUFA-containing diets occurred at lower light intensity, thereby exhibiting greater rod sensitivity, than the other diet groups. These findings indicate that preformed dietary (n-3) LCPUFA is more effective than ALA in enriching plasma DHA during perinatal development and results in improved visual performance in developing dogs.