In male rats with concurrent iron and (n-3) fatty acid deficiency, provision of either iron or (n-3) fatty acids alone alters monoamine metabolism and exacerbates the cognitive deficits associated with combined deficiency

Concurrent deficiencies of iron (Fe) (ID) and (n-3) fatty acids [(n-3)FAD)] in rats can alter brain monoamine pathways and impair learning and memory. We examined whether repletion with Fe and DHA/EPA, alone and in combination, corrects the deficits in brain monoamine activity (by measuring monoamines and related gene expression) and spatial working and reference memory [by Morris water maze (MWM) testing] associated with deficiency. Using a 2 × 2 design, male rats with concurrent ID and (n-3)FAD [ID+(n-3)FAD] were fed an Fe+DHA/EPA, Fe+(n-3)FAD, ID+DHA/EPA, or ID+(n-3)FAD diet for 5 wk [postnatal d 56-91]. Biochemical measures and MWM performance after repletion were compared to age-matched control rats. The provision of Fe in combination with DHA/EPA synergistically increased Fe concentrations in the olfactory bulb (OB) (Fe x DHA/EPA interaction). Similarly, provision of DHA/EPA in combination with Fe resulted in higher brain DHA concentrations than provision of DHA alone in the frontal cortex (FC) and OB (P < 0.05). Dopamine (DA) receptor D1 was upregulated in the hippocampus of Fe+DHA/EPA rats (fold-change = 1.25; P < 0.05) and there were significant Fe x DHA/EPA interactions on serotonin (5-HT) in the OB and on the DA metabolite dihydroxyphenylacetic acid in the FC and striatum. Working memory performance was impaired in ID+DHA/EPA rats compared with controls (P < 0.05). In the reference memory task, Fe+DHA/EPA improved learning behavior, but Fe or DHA/EPA alone did not. These findings suggest that feeding either Fe or DHA/EPA alone to adult rats with both ID and (n-3)FAD affects the DA and 5-HT pathways differently than combined repletion and exacerbates the cognitive deficits associated with combined deficiency.     

The (n-3) fatty acid dose, independent of the (n-6) to (n-3) fatty acid ratio, affects the plasma fatty acid profile of normal dogs

The purpose of this study was to determine whether the dose of (n-3) fatty acids (FA) administered, independent of the relative ratio of (n-6) to (n-3) FA in the food, influences plasma FA composition in dogs. Healthy female, geriatric beagles (7-10 y old) were fed foods containing (n-6) to (n-3) FA ratios of either 40.0:1 or 1.4:1 for 12 wk (study 1) or 36 wk (study 2). In study 3, beagles were fed food with the same 1:1 ratio of (n-6) to (n-3) FA, but with increasing concentrations of (n-6) and (n-3) FA. Plasma FA concentrations were measured after completing the feeding studies. In studies 1 and 2, dogs fed fish oil-enriched food with a high (n-3) FA concentration had higher plasma total (n-3) FA, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) concentrations and lower plasma total (n-6) FA, linoleic acid, and arachidonic acid concentrations than dogs fed corn oil-enriched food with a low (n-3) FA concentration (P < 0.001). Both inclusion of fish oil (P < 0.001) and increased food intake independent of treatment effects increased the plasma DHA (P = 0.05) concentration. Furthermore, constancy of the dose of (n-3) FA administered over long periods of time was necessary to maintain plasma levels of total (n-3) FA, EPA, and DHA. In study 3, up to certain dietary concentrations (6.3 g total (n-3) FA/kg food for DHA and 9.8 g total (n-3) FA/kg food for EPA), the dose of (n-3) FA administered, independent of the (n-6) to (n-3) FA ratio, determined the plasma (n-3) FA composition. Results from our studies indicate that approximately 175 mg DHA/(kg body weight . d) is required to attain maximum plasma levels of DHA.     

Plasma concentrations of (n-3) highly unsaturated fatty acids are good biomarkers of relative dietary fatty acid intakes: a cross-sectional study

A cross-sectional study was conducted to clarify the associations of lifestyle factors (habitual exercise, alcohol intake and smoking habit) and plasma fatty acid (FA) concentrations as biomarkers of dietary FA intakes. We collected 7-d weighed diet records, lifestyle information and blood samples from 15 male and 79 female Japanese dietitians, and estimated dietary FA intakes and analyzed plasma FA concentrations. Plasma concentrations of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and (n-3) highly unsaturated FA (HUFA) derived from marine foods, but not linoleic and alpha-linolenic acid from plant origins, demonstrated positive correlations with dietary intakes (r = 0.303-0.602, P < 0.05) in both genders. Multiple linear regression analyses adjusted for age, BMI, total energy intake, fat (or respective FA) consumption and lifestyle factors showed that dietary intakes of EPA, DHA and (n-3) HUFA were positively associated with age in men (P < 0.05) and negatively associated with BMI in women [P < 0.01 for DHA and (n-3) HUFA]. The plasma concentrations of EPA, DHA and (n-3) HUFA in women were found to be positively associated with age and marine oil (or respective FA) intake (P < 0.01), and negatively associated with total energy intake [P < 0.05 for EPA and (n-3) HUFA]. Lifestyle factors were not associated with dietary FA intakes and plasma FA concentrations. These findings suggest that the plasma concentrations of EPA, DHA and (n-3) HUFA might be useful biomarkers for the assessment of relative FA intakes without considering associations with habitual exercise, alcohol intake and smoking habit.     

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.     

Impact of parenteral n-3 fatty acids on experimental acute colitis

The present study was undertaken to investigate the effects of parenteral lipid emulsions (LE) enriched with n-3 fatty acids (n-3 FA) in experimental acute colitis. Seventy-four adult male Wistar rats were randomized into six groups, five of which had acetic acid-induced colitis. The animals received a fat-free diet and water ad libitum in individual metabolic cages. By a central venous catheter, saline was infused (0.5 ml/h) into the control groups CS (without colitis) and CC (with colitis), while the test groups received specific LE for 7 days. The n-3/n-6 FA ratio and the lipidic compositions regarding long chain (LCT) and medium chain (MCT) triglycerides were: group L--1:7.7 (LCT, n = 12), M--1:7.0 (MCT and LCT, n = 12), LW-3--1:4.5 (LCT plus n-3 FA, n = 12) and MW-3--1:3.0 (MCT and LCT plus n-3 FA, n = 13). The frequency of diarrhea, oral intake/body weight ratio, intestinal alterations, macrophage cellularity were evaluated and colonic concentrations of leukotrienes (LTB4, LTC4), prostaglandins (PGE2) and thromboxanes (TXB2) were measured. Groups M, MW-3 and LW-3 had less diarrhea than the CC group (P<0.05). Average oral intake/body weight ratio in MW-3 animals was comparable to the CS and better than the CC group. n-3 FA treated rats (LW-3 and MW-3) presented less intestinal inflammatory alterations than CC rats. Mucosal ulcer formation in MW-3 group did not differ from CS rats. M and MW-3 rats had less macrophages in the colon than the CC group. Compared with CC group, lower concentrations of LTB4 in the CS, LW-3 and MW-3 groups; of PGE2 in the CS, M and MW-3 groups; and of TXB2 in the CS and MW-3 groups were found. Mean concentrations of LTC4 did not differ among the groups. Thus, a LCT-containing LE with a low n-3-n-6 ratio does not modify inflammatory colitis manifestations; LE with a high n-3-n-6 ratio reduces diarrhea, preserves oral intake-weight ratio, attenuates morphological consequences and decreases colonic concentrations of inflammatory mediators; MCT/LCT-containing LE with 1:3 n-3-n-6 ratio exerts the most profound beneficial impact on the inflammatory response.     

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.     

Relation between dietary n-3 and n-6 fatty acids and clinically diagnosed dry eye syndrome in women

BACKGROUND: Dry eye syndrome (DES) is a prevalent condition, but information on risk or protective factors is lacking. OBJECTIVE: We aimed to determine the association between the dietary intake and ratio of n-3 and n-6 fatty acids (FAs) and DES occurrence. DESIGN: Of the 39876 female health professionals in the Women's Health Study (WHS), 32470 women aged 45-84 y who provided information on diet and DES were cross-sectionally studied. We assessed FA intakes by using a validated food-frequency questionnaire and assessed DES by using self-reports of clinically diagnosed cases. Of the sample, 1546 (4.7%) subjects reported DES. We used logistic regression models to estimate the odds ratios (ORs) and 95% CIs to describe the relation of FA intake with DES. RESULTS: After adjustment for demographic factors, hormone therapy, and total fat intake, the OR for the highest versus the lowest quintile of n-3 FAs was 0.83 (95% CI: 0.70, 0.98; P for trend = 0.05). A higher ratio of n-6 to n-3 FA consumption was associated with a significantly increased risk of DES (OR: 2.51; 95% CI: 1.13, 5.58) for >15:1 versus <4:1 (P for trend = 0.01). In addition, tuna consumption [1 serving was 113 g (4 oz)] was inversely associated with DES (OR: 0.81; 95% CI: 0.66, 0.99 for 2-4 servings/wk; OR: 0.32; 95% CI: 0.13, 0.79 for 5-6 servings/wk versus < or =1 serving/wk; P for trend = 0.005). CONCLUSIONS: These results suggest that a higher dietary intake of n-3 FAs is associated with a decreased incidence of DES in women. These findings are consistent with anecdotal clinical observations and postulated biological mechanisms.     

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.     

Maternal dietary (n-3) fatty acid deficiency alters neurogenesis in the embryonic rat brain

Docosahexaenoic acid [22:6(n-3)] is enriched in brain membrane phospholipids and essential for brain function. Neurogenesis during embryonic and fetal development requires synthesis of large amounts of membrane phospholipid. We determined whether dietary (n-3) fatty acid deficiency during gestation alters neurogenesis in the embryonic rat brain. Female rats were fed diets with 1.3% energy [(n-3) control] or 0.02% energy [(n-3) deficient], from alpha-linolenic acid [18:3(n-3)], beginning 2 wk before gestation. Morphometric analyses were performed on embryonic day 19 to measure the mean thickness of the neuroepithelial proliferative zones corresponding to the cerebral cortex (ventricular and subventricular zones) and dentate gyrus (primary dentate neuroepithelium), and the thickness of the cortical plate and sectional area of the dentate gyrus. Phospholipids and fatty acids were determined by HPLC and GLC. Docosahexaenoic acid was 55-65% lower and (n-6) docosapentaenoic acid [22:5(n-6)] was 150-225% higher in brain phospholipids at embryonic day 19 in the (n-3) deficient (n = 6 litters) than in the control (n = 5 litters) group. The mean thickness of the cortical plate and mean sectional area of the primordial dentate gyrus were 26 and 48% lower, respectively, and the mean thicknesses of the cortical ventricular zone and the primary dentate neuroepithelium were 110 and 70% higher, respectively, in the (n-3) deficient than in the control embryonic day 19 embryos. These studies demonstrate that (n-3) fatty acid deficiency alters neurogenesis in the embryonic rat brain, which could be explained by delay or inhibition of normal development.     

Lead exposure and (n-3) fatty acid deficiency during rat neonatal development alter liver, plasma, and brain polyunsaturated fatty acid composition

Lead (Pb) exposure has been reported to increase arachidonic (AA) and docosahexaenoic (DHA) acids. To determine whether Pb effects on fatty acid composition are influenced by dietary (n-3) fatty acid restriction, weanling female rats were fed either an (n-3)-adequate or -deficient diet to maturity and mated. At parturition, dams in each group were subdivided to receive either 0.2% Pb or Na-acetate in their drinking water during lactation only. Pups were analyzed for fatty acid content in liver, plasma, and brain at either 3 or 11 wk. The (n-3)-deficient diets markedly decreased total (n-3) fatty acids, and increased total (n-6) fatty acids including both AA and docosapentaenoic (n-6) in each compartment (P < 0.05). The main effects of Pb were in the livers of weanling rats where there was a 56% loss in total fatty acid concentration concurrent with increased relative percentages of AA and DHA. Thus, because there was a greater percentage of liver nonessential fatty acid lost relative to the essential fatty acids (EFA), there was no net change in AA concentration. There was a diet x Pb interaction for a decrease in liver DHA concentration evident only in the (n-3)-adequate group. There were also diet x Pb interactions in plasma at 11 wk and in brain at 3 wk. These data are consistent with the hypothesis of a Pb-induced increase in fatty acid catabolism, perhaps as a source of energy.     

The dopamine mesocorticolimbic pathway is affected by deficiency in n-3 polyunsaturated fatty acids

BACKGROUND: Several findings in humans support the hypothesis of links between n-3 polyunsaturated fatty acid (PUFA) status and psychiatric diseases. OBJECTIVE: The involvement of PUFAs in central nervous system function can be assessed with the use of dietary manipulation in animal models. We studied the effects of chronic dietary n-3 PUFA deficiency on mesocorticolimbic dopamine neurotransmission in rats. DESIGN: Using dual-probe microdialysis, we analyzed dopamine release under amphetamine stimulation simultaneously in the frontal cortex and the nucleus accumbens. The messenger RNA (mRNA) expression of vesicular monoamine transporter(2) and dopamine D(2) receptor was studied with the use of in situ hybridization. The protein expression of the synthesis-limiting enzyme tyrosine 3-monooxygenase (tyrosine 3-hydroxylase) was studied with the use of immunocytochemistry. RESULTS: Dopamine release was significantly lower in both cerebral areas in n-3 PUFA-deficient rats than in control rats, but this effect was abolished in the frontal cortex and reversed in the nucleus accumbens by reserpine pretreatment, which depletes the dopamine vesicular storage pool. The mRNA expression of vesicular monoamine transporter(2) was lower in both cerebral areas in n-3 PUFA-deficient rats than in control rats, whereas the mRNA expression of D(2) receptor was lower in the frontal cortex and higher in the nucleus accumbens in n-3 PUFA-deficient rats than in control rats. Finally, tyrosine 3-monooxygenase immunoreactivity was higher in the ventral tegmental area in n-3 PUFA-deficient rats than in control rats. CONCLUSIONS: Our results suggest that the mesolimbic dopamine pathway is more active whereas the mesocortical pathway is less active in n-3 PUFA-deficient rats than in control rats. This provides new neurochemical evidence supporting the effects of n-3 PUFA deficiency on behavior.     

(N-3) long-chain polyunsaturated fatty acids prolong survival following myocardial infarction in rats

Many clinical studies report that (n-3) PUFAs decrease the incidence of sudden death in patients with coronary artery disease after myocardial infarction (MI). However, the mechanisms for the beneficial effects of (n-3) PUFAs are unknown. The objectives of the present study were to confirm the findings from clinical trials using an animal model of MI in which dietary intake could be closely controlled and to utilize the model to investigate molecular mechanisms for the beneficial effects of (n-3) PUFAs. Male rats were subjected to coronary ligation to induce MI and were randomly assigned to diets high in (n-6) (58% of lipid) or (n-3) (28% of lipid) PUFAs for 6 mo. A diet high in (n-3) PUFAs was associated with an improvement in 6-mo survival (89.2% vs. 64.9%, P = 0.013) compared with rats consuming a diet high in (n-6) PUFAs (n = 37/group). In a separate study (n = 5 rats/diet group), the (n-3) PUFA diet decreased the (n-6):(n-3) PUFA ratio in plasma (0.6 +/- 0.1 vs. 7.9 +/- 1.8, P < 0.05) and cardiac tissue (0.9 +/- 0.1 vs. 11.8 +/- 1.6, P < 0.05) of rats fed for 4 wk. The increased survival in the (n-3) diet group was associated with decreased cardiac activities of protein kinase A and calcium calmodulin-dependent kinase II by 33-38% (P < 0.05) and a 28% decrease (P < 0.05) in phosphorylation (activation) of the ryanodine receptor calcium release channel. Based upon our results, we speculate that decreased activities of protein kinases induced by diets high in (n-3) PUFAs are associated with a decrease in sudden death after MI in rats.     

Lead exposure and (n-3) fatty acid deficiency during rat neonatal development affect subsequent spatial task performance and olfactory discrimination

Docosahexaenoic acid [22:6(n-3), DHA] is important for optimal infant central nervous system development, and lead (Pb) exposure during development can produce neurological deficits. Long-Evans strain rats were fed either an (n-3) deficient [(n-3) Def] diet to produce brain DHA deficiency, or an adequate [(n-3) Adq] diet through 2 generations. At the birth of the 2nd generation, the dams were subdivided into 4 groups and supplied drinking water containing either 5.27 mmol/L (Pb) or sodium (Na) acetate until weaning. Rats were killed at 3 wk (weaning) and 11 wk (maturity) for brain Pb and fatty acid analysis. Spatial task and olfactory-cued behavioral assessments were initiated at 9 wk. Rats in the (n-3) Def group had a 79% lower concentration of brain DHA compared with the (n-3) Adq group with no effect of Pb exposure. At weaning, Pb concentrations were 7.17 +/- 0.47 nmol Pb/g of brain (wet weight) in the (n-3) Adq-Pb group and 6.49 +/- 0.63 nmol Pb/g of brain (wet weight) in the (n-3) Def-Pb group. At maturity, the brains contained 1.30 +/- 0.22 and 1.07 +/- 0.12 nmol Pb/g (wet weight), respectively. In behavioral testing, significant effects of both Pb and DHA deficiency were observed in the Morris water maze probe trial and in 2-odor olfactory discrimination acquisition and olfactory-based reversal learning tasks. Both lactational Pb exposure and (n-3) fatty acid deficiency led to behavioral deficits with additive effects observed only in the acquisition of 2-odor discriminations.     

Dietary (n-3) polyunsaturated fatty acids up-regulate plasma leptin in insulin-resistant rats

The study was designed to evaluate the chronic regulation of plasma leptin by dietary (n-3) polyunsaturated fatty acids (PUFA) in insulin-resistant, sucrose-fed rats. Male Sprague-Dawley rats were randomly assigned to consume for 3 or 6 wk a diet containing 57.5% (g/100 g) sucrose and 14% lipids as either fish oil (SF) or control oils (SC). After 3 and 6 wk of consuming the SF diet, plasma leptin was 70% (P < 0.001) and 75% (P < 0.05) greater, respectively, than in rats fed the SC diet. The same result was found when plasma leptin was adjusted by total fat mass, as measured by dual-energy X-ray absorptiometry. Despite high leptin levels, food intake of rats fed the SF diet was greater than in SC-fed rats without any difference in body weight or total fat mass. After 3 wk, accumulated leptin in epididymal and retroperitoneal adipose tissue was higher in the SF-fed rats than in the SC-fed rats. However, after 6 wk, tissue leptin in the SF-fed rats did not differ from that of the SC-fed rats. The SF diet increased adipose tissue glucose transporter-4 protein quantity and prevented the sucrose-induced elevations in plasma triglycerides and free fatty acids. When all SC- and SF-fed rats (both diets and feeding durations) were considered, plasma leptin levels were positively correlated with body weight (r = 0.5, P < 0.0001) and with total fat mass (r = 0.5, P < 0.0005). These results suggest that plasma leptin at a given time could be inappropriately high for a given fat mass in insulin-sensitive rats fed (n-3) PUFA.     

Fish oil supplementation of control and (n-3) fatty acid-deficient male rats enhances reference and working memory performance and increases brain regional docosahexaenoic acid levels

Most previous studies have focused on improved reference memory and recovery of whole brain docosahexaenoic acid [DHA, 22:6(n-3)] levels in DHA-deficient animals supplemented with fish oil (FO) or switched to an adequate DHA-enriched diet. The aims of this study were to determine whether reference and working memory performance can be enhanced in control male rats and improved in (n-3) fatty acid-deficient male rats given an FO supplement and whether brain DHA accumulation, deficiency, and recovery are region specific. From the embryo to postnatal d 140, 4 groups of rats were fed a nonpurified or sunflower oil-based (n-3) fatty acid-deficient diet alone or supplemented with (n-3) fatty acids from FO representing approximately 0.3% of the energy source. The male rats were tested at postnatal d 102-130 for spatial learning memory performance in the Morris water maze. The fatty acid composition of different brain regions was analyzed by GC. Rats fed the (n-3) fatty acid-deficient diet showed significantly poorer reference and working memory, and FO supplementation partially rescued both memory performances. Furthermore, FO supplementation during brain development and adulthood in normal rats resulted in significant enhancement of both memories. Following dietary DHA repletion, the hippocampus and olfactory bulbs accumulated more DHA, were more resistant to dietary DHA deprivation, and showed better DHA recovery than the visual cortex, frontal cortex, and cerebellum. These results suggest that DHA is critical for the development and maintenance of learning memory performance.     

(n-3) PUFA alter raft lipid composition and decrease epidermal growth factor receptor levels in lipid rafts of human breast cancer cells

To determine the mechanism by which the (n-3) fatty acids (FA) eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) decrease proliferation and induce apoptosis in MDA-MB-231 human breast cancer cells, we examined the effects of EPA and DHA on the lipid composition of lipid rafts as well as epidermal growth factor receptor (EGFR) raft localization and phosphorylation. (n-3) FA (a combination of EPA and DHA) inhibited (P < 0.05) the growth of MDA-MB-231 cells by 48-62% in the presence and absence, respectively, of linoleic acid (LA). More EPA and DHA were incorporated into lipid rafts isolated from MDA-MB-231 cells after treatment with (n-3) FA compared with cells treated with LA (P < 0.05). EPA and DHA treatment decreased (P < 0.05) lipid raft sphingomyelin, cholesterol, and diacylglycerol content and, in the absence of LA, EPA and DHA increased (P < 0.05) raft ceramide levels. Furthermore, there was a marked decrease in EGFR levels in lipid rafts, accompanied by increases in the phosphorylation of both EGFR and p38 mitogen-activated protein kinase (MAPK), in EPA+DHA-treated cells (P < 0.05). As sustained activation of the EGFR and p38 MAPK has been associated with apoptosis in human breast cancer cells, our results indicate that (n-3) FA modify the lipid composition of membrane rafts and alter EGFR signaling in a way that decreases the growth of breast tumors.     

R3230AC rat mammary tumor and dietary long-chain (n-3) fatty acids change immune cell composition and function during mitogen activation.

Because anticancer immunity declines progressively with tumor growth, a major focus of current research in tumor immunology is the development of means to stimulate the host immune system. This study determined the effects of dietary long-chain (n-3) fatty acids and tumor burden on immune cell phospholipid composition and membrane-mediated immune defense in rats implanted with the R3230AC mammary adenocarcinoma. Fischer 344 rats (145 +/- 2 g) were fed one of two semipurified diets (20 g/100 g fat) for 21 d before and 17 d after tumor implantation. Diets provided long-chain (n-3) fatty acids at 0 or 50 g/kg of total fat. Mammary tumor growth was 31% lower (P = 0.1) in rats fed long-chain (n-3) fatty acids. Dietary long-chain (n-3) fatty acids had beneficial effects on several host immune defenses, including activation of CD8(+) T cells and type-1 cytokine (interferon-gamma and tumor necrosis factor-alpha) production (P < 0.05). Upregulated immune function in tumor-bearing rats fed the high (n-3) diet occurred concurrently with specific changes in the major membrane phospholipids phosphatidylcholine and phosphatidylethanolamine in high (n-3)-fed rats. Because membrane composition plays a critical role in immune function, additional work is needed to determine the relationship between alterations in the phospholipid composition of immune cells during cancer and subsequent upregulation of host defense in the tumor-bearing state.     

Long-chain (n-3) polyunsaturated fatty acids prevent metabolic and vascular disorders in fructose-fed rats

The crossover relationship between cardiometabolic risk, in terms of insulin resistance and vascular dysfunction, and the fatty acid (FA) profile of insulin-sensitive tissues as well as the dietary FA impact has almost never been explored in the same experiment. In this study, the intake of alpha-linolenic acid (ALA) alone and/or with its higher metabolites, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were evaluated in a nonobese, hypertriglyceridemic and insulin-resistant rat model, that exhibits the 2 main characteristics of metabolic syndrome. Wistar rats were fed either a cornstarch and (n-6) PUFA-based diet (C-N6) or a 66% fructose diet over a 10-wk period. Fructose-fed rats received a diet containing ALA alone (F-ALA group) or ALA plus EPA and DHA (F-LC3 group) or no (n-3) PUFA (F-N6 group). The 10-wk high-fructose diet (F-N6) induced an insulin-resistant state, as assessed by glucose and insulin tolerance tests. Insulin resistance was linked to a specific FA pattern in insulin-sensitive tissues, which probably involved modifications of Delta9, Delta6, and Delta5-desaturases. This pathological status was related to high cardiovascular risk as assessed by increases in systolic and diastolic blood pressures and particularly by the increase of pulse pressure, an index of vascular stiffness obtained from telemetry investigations. The (n-3) experimental diets prevented changes in the FA patterns in insulin-sensitive tissues, insulin resistance, and vascular dysfunction. This beneficial effect was large with an intake of long chain (n-3) PUFA (ALA+EPA+DHA) and to a lesser extent with dietary ALA alone.     

Polyunsaturated (n-3) fatty acids susceptible to peroxidation are increased in plasma and tissue lipids of rats fed docosahexaenoic acid-containing oils

Docosahexaenoic acid [DHA, 22:6(n-3)], a major component of membrane phospholipids in brain and retina, is profoundly susceptible to oxidative stress in vitro. The extent of this peroxidation in organs when DHA is ingested in mammals, however, is not well elucidated. We investigated the effect of dietary DHA-containing oils (DHA 7.0-7.1 mol/100 mol total fatty acids), in the form of triacylglycerols (TG), ethyl esters (EE) and phospholipids (PL), on tissue lipid metabolism and lipid peroxidation in rats. Groups of Sprague-Dawley rats were fed semipurified diets containing 15 g/100 g test oils and were compared with those fed 80% palm oil and 20% soybean oil as the control (unsupplemented group) for 3 wk. The DHA oil diets markedly increased (P: < 0.05) the levels of DHA in the plasma, liver and kidney, 1.5-1.9, 2.5-3.8 and 2.2-2.5 times the control values, respectively, whereas there was a concomitant reduction (P: < 0.05) in arachidonic acid. All forms of DHA oil caused lower TG concentrations in plasma (P: < 0.05) and liver (P: < 0.05), but had no effect in kidney. The DHA oil-fed rats had greater phospholipid hydroperoxide accumulations in plasma (191-192% of control rats), liver (170-230%) and kidney (250-340%), whereas the alpha-tocopherol level was reduced concomitantly (21-73% of control rats). Consistent with these results, rats fed DHA-containing oils had more thiobarbituric reactive substances in these organs than the controls. Thus, high incorporation of (n-3) fatty acids (mainly DHA) into plasma and tissue lipids due to DHA-containing oil ingestion may undesirably affect tissues by enhancing susceptibility of membranes to lipid peroxidation and by disrupting the antioxidant system.