Effect Of Dietary Docosahexaenoic Acid Research Articles

The effect of dietary docosahexaenoic acid (DHA; 22:6n-3) on photoreceptor abundance, rhodopsin expression and growth in developing gilthead sea bream (Sparus aurata) larvae

This study determined the effect of prey DHA on larval gilthead sea bream (GSB; Sparus aurata) photoreceptor abundance, rhodopsin expression, and growth performance. It was carried out in a twenty-eight 400 l conical tank system that was stocked with 100 viable GSB eggs/l/tank. This allowed the testing of 4 levels of rotifer DHA; 0.99 (Low; L), 1.9 (Intermediate low; I-L), 3.2 (Intermediate high; I-H) and 12.1(High; H) mg DHA/g DW rotifer, which were fed (10 rotifers/ml) to 3-16 DPH larvae. These rotifer diets continued to be offered to 17-34 DPH fish, although these larvae predominantly fed on 4 DHA enriched Artemia nauplii treatments that were offered at a concentration from 0.1 nauplii/ml to 4 nauplii/ml, depending on larval age. This resulted in 4 DHA rotifer-Artemia ranges: 0.99-0.0 (L), 1.9-2.6 (I-L), 3.2-7.2 (I-H), and 12.1-11.77 (H) mg DHA/g DW. The 4 DHA treatments and ranges were tested in replicates of 7 conical tanks per treatment. Increasing rotifer DHA significantly (P<0.0001) improved TL, in an exponential manner, throughout larval rearing. DW in 34 DPH larvae was markedly (P<0.05) enhanced with dietary DHA inclusion in the rotifers and Artemia. There was a significant (P < 0.005) prey DHA dose dependent range effect on the abundance of photoreceptor cells in the retina of 34 DPH larvae. The gene expression of rhodopsin in GSB larvae was significantly (P<0.05) upregulated with dietary DHA dose range and larval age (P<0.0001). This study established a link between dietary DHA level with photoreceptor abundance and rhodopsin expression, which led to improved vision, prey acquisition, and growth in developing GSB larvae.

Comparative evaluation on the effects of dietary docosahexaenoic acid on growth performance, fatty acid profile and lipid metabolism in two sizes of abalone Haliotis discus hannai Ino

A 93-day feeding trial was conducted to comparatively evaluate the effects of graded levels of dietary docosahexaenoic acid (DHA) (0.06%, 0.46%, 0.99%, 1.57%, 1.95% and 2.25%) on growth performance, fatty acid profile and lipid metabolism in two different sizes of abalone Haliotis discus hannai (initial body weight: 2.83 ± 0.03 g and 26.81 ± 0.17 g, respectively). Results showed that 0.99%–1.95% of dietary DHA contents significantly increased the weight gain rate (WGR) in large size of abalone (P < 0.05), while the WGR in small size of abalone was significantly increased by the 0.46%–0.99% of dietary DHA contents (P < 0.05). There was no significant difference in the survival of abalone among all the six groups (P > 0.05). Based on the WGR, the optimal dietary DHA content for large and small size abalone were estimated to be 1.32% and 0.88%, respectively. Dietary DHA supplementation significantly increased the activities of trypsin and lipase in the intestine, the content of ∑n-3 polyunsaturated fatty acids (PUFA) and ∑n-3/n-6 PUFA ratio in digestive gland in both sizes of abalone (P < 0.05). The total glyceride concentration in the cell-free hemolymph in two sizes of abalone was decreased. In large size of abalone, 1.95%–2.25% of dietary DHA reduced the lipid content in digestive gland. Lipogenic genes in the digestive gland, including sterol regulatory element binding protein-1 (srebp-1) and diacylglycerol acyltransferase, were up-regulated in the 0.46%–1.57% DHA group (P > 0.05). The mRNA expression levels of hormone sensitive lipase (hsl) and carnitine palmitoyl transferase-1 (cpt-1) of lipolytic genes in the digestive gland were significantly increased in the 0.46% and 0.99% DHA groups, respectively (P < 0.05). In the small size of abalone, the lipid content in digestive gland and soft body decreased significantly in the 1.95% and 2.25% DHA groups, respectively (P < 0.05). Lipogenic genes in the digestive gland, including srebp-1 and acetyl-CoA carboxylase, were significantly down-regulated in the 0.99%–1.95% DHA group (P < 0.05). Lipolytic genes in the digestive gland, including hsl and cpt-1, were not significantly different from the control group (P > 0.05). In conclusion, based on the WGR, the dietary DHA requirements for large and small size of abalone were estimated to be 1.32% and 0.88%, respectively. Dietary DHA reduced lipid deposition in both sizes of abalone by promoting lipid decomposition and inhibiting lipid synthesis.

Discrepant modulating effects of dietary docosahexaenoic acid on cerebral lipids, fatty acid transporter expression and soluble beta-amyloid levels in ApoE-/- and C57BL/6J mice.

The study was designed to explore the role of apolipoprotein E (ApoE) deficiency concomitant with dietary docosahexaenoic acid (DHA) treatment on brain β-amyloid (Aβ) and lipid levels. A 5-month dietary DHA intervention was conducted in ApoE-deficient (ApoE-/- ) mice and wild-type C57BL/6J (C57 wt) mice. The Morris water maze test was performed to assess the behaviour of the animals. The cortical contents of soluble Aβ1-40 and Aβ1-42 were detected by enzyme-linked immunosorbent assay (ELISA). Cortical fatty acid levels were detected by gas chromatography. Gene and protein expression of molecules associated with cerebral Aβ and lipid metabolism were measured using real-time polymerase chain reaction (PCR), Western blot and histological methods. DHA treatment increased the content of cortical DHA and n-3 polyunsaturated fatty acids (n-3 PUFAs) but decreased the ratio of n-6/n-3 PUFAs in ApoE-/- mice; whereas the content of cortical DHA and n-3 PUFAs in C57 wt mice remained unchanged after DHA treatment. Cerebral Fabp5 and Cd36 gene expression were significantly downregulated in DHA-fed C57 wt mice; cerebral Cd36 and Scarb1 gene expression were significantly upregulated, whereas Fabp5 gene expression was downregulated in DHA-fed ApoE-/- mice. In comparison with C57 wt mice, the content of cortical soluble Aβ1-42 , total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) increased, whereas the level of high-density lipoprotein cholesterol (HDL-C) decreased in ApoE-/- mice. Interestingly, these differences were significantly reversed by DHA dietary treatment. DHA intervention has discrepant impacts on cerebral lipids, fatty acid transporter expression and soluble Aβ levels in ApoE-/- and C57 wt mice, suggesting the modifying role of ApoE status on the responses of cerebral lipids and Aβ metabolism to DHA treatment.

Impact of Dietary Docosahexaenoic Acid : Eicosapentaenoic Acid Ratio on Growth, Fatty Acid Composition, Lipid Metabolism, and Antioxidant Status of Juvenile Hybrid Grouper (Brown‐marbled Grouper Epinephelus fuscoguttatus ♀ × Giant Grouper E. lanceolatus ♂)

AbstractThe present study was conducted to evaluate the effects of dietary docosahexaenoic acid : eicosapentaenoic acid (DHA:EPA) ratio on growth, lipid metabolism, and antioxidant status of hybrid grouper (Brown‐marbled Grouper Epinephelus fuscoguttatus ♀ × Giant Grouper E. lanceolatus ♀). Fish (initial body weight = 20.8 ± 0.03 g; mean ± SE) were fed six different isoproteic (53%) and isolipidic (7%) diets containing graded DHA:EPA ratios (D/E) of 0.54, 0.97, 1.51, 2.01, 2.41, and 2.85. No significant difference in weight gain was recorded in fish fed with different dietary DHA:EPA ratios. The DHA:EPA ratio in fish muscle was significantly increased as the dietary ratio increased. Relative messenger RNA expression of hepatic elongase of very long fatty acids 5 (elovl5*) and delta‐6 fatty acyl desaturase (Δ6 fad*) in the D/E 2.41 and 2.85 groups was significantly higher than that in the other treatments. Lipid droplet accumulation was significantly higher in the liver of the D/E 0.54 and 0.97 groups than in the other groups. Lipogenesis‐related genes (fatty acid synthase [FAS*] and acetyl coenzyme A carboxylase [ACC*]) were up‐regulated by lower dietary DHA:EPA ratios (0.54 and 0.97), whereas lipolysis‐related genes (peroxisome proliferator‐activated receptor alpha [PPARα*] and hormone‐sensitive lipase [HSL*]) were down‐regulated. The expression of genes related to antioxidative capacity, including nuclear factor erythroid 2‐related factor 2 (Nrf2*), manganese superoxide dismutase (MnSOD*), and peroxiredoxin (Prx*), was significantly down‐regulated in the D/E 1.51 and 2.01 groups compared with other treatments, while Kelch‐like ECH‐associated protein 1 (Keap1*) was up‐regulated. The above results suggest that dietary DHA:EPA ratio influences muscle fatty acid composition and lipid metabolism by altering the expression of lipogenesis‐ and lipolysis‐related genes, and dietary DHA:EPA ratio may also regulate the antioxidant capacity of juvenile hybrid grouper.

Fatty Acid Composition and Digestive Enzyme Activities of Rainbow Trout in Response to Dietary Docosahexaenoic Acid (DHA) and Eicosapentaenoic Acid (EPA) During Salinity Acclimation

This physiological study aimed to evaluate the effects of dietary docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on the fatty acid composition and digestive enzyme activities of rainbow trout (Oncorhynchus mykiss) during salinity acclimation. Rainbow trout with an average initial weight of 90.61 g ±9.25 g were fed diets with the quantities of DHA and EPA equaling to 0.54%, 0.95%, 1.40% and 1.79% (abbreviated as DE-0.54, DE-0.95, DE-1.40, and DE-1.79, respectively) for eight weeks, after which the gastric and intestinal fatty acids composition were analyzed. Subsequently, the fish underwent salinity acclimation. On days 1, 4, 7, and 14 after the freshwater was replaced by seawater and at the end of the 8-week period, gastric and intestinal digestive enzyme activities were determined. The results showed that the gastric and intestinal DHA and EPA contents of the fish were positively correlated to their dietary DHA and EPA levels. Low dietary DHA and EPA levels inhibited the protease activity of rainbow trout. Fish in the DE-0.54 group increased the lipase activity to enhance the utilization of lipids maybe due to the inadequate essential fatty acids for fish in this group. Hence, rainbow trout in the DE-0.54 group failed to maintain suitable activities of digestive enzymes after salinity acclimation. Therefore, a diet with minimum 0.95% DHA and EPA levels is necessary for rainbow trout during salinity acclimation.

Effects of Supplementation of Microalgae (Aurantiochytrium sp.) to Laying Hen Diets on Fatty Acid Content, Health Lipid Indices, Oxidative Stability, and Quality Attributes of Meat.

The present study is conducted to investigate the effects of dietary docosahexaenoic acid (DHA)-rich microalgae (MA, Aurantiochytrium sp.) on health lipid indices, stability, and quality properties of meat from laying hens. A total of 450 healthy 50-wk-old Hy-Line Brown layers were randomly allotted to 5 groups (6 replicates of 15 birds each), which received diets supplemented with 0, 0.5, 1.0, 1.5, and 2.0% MA for 15 weeks. Fatty acid contents and quality properties of breast and thigh muscles from two randomly selected birds per replicate (n = 12) were measured. The oxidative stability of fresh, refrigerated, frozen, and cooked meat was also determined. Results indicated that supplemental MA produced dose-dependent enrichments of long-chain n-3 polyunsaturated fatty acids (n-3 LC-PUFA), predominantly DHA, in breast and thigh muscles, with more health-promoting n-6/n-3 ratios (1.87–5.27) and favorable lipid health indices (p < 0.05). MA supplementation did not affect tenderness (shear force) and color (L*, a*, and b* values) of hen meat nor muscle endogenous antioxidant enzymes and fresh meat oxidation (p > 0.05). However, the n-3 LC-PUFA deposition slightly increased lipid oxidation in cooked and stored (4 °C) meat (p < 0.05). In conclusion, MA supplementation improves the nutritional quality of hen meat in terms of lipid profile without compromising meat quality attributes. Appropriate antioxidants are required to mitigate oxidation when such DHA-enriched meat is subjected to cooking and storage.

Docosahexaenoic acid protects against palmitate-induced mitochondrial dysfunction in diabetic cardiomyopathy

ObjectiveRegular consumption of n-3 polyunsaturated fatty acids is associated with decreased cardiovascular morbidity and mortality. This study assessed the therapeutic effect of docosahexaenoic acid (DHA) in palmitic acid (PA)-induced cytotoxicity in vitro and in rats fed a high-fat diet (HFD). MethodsH9C2 cells and rat primary cardiomyoblasts were exposed to PA or PA + DHA for 24 h. PA-induced lipotoxicity and mitochondrial dysfunction were evaluated by immunostaining, real-time PCR, cardiomyocyte contraction and transmission electron microscopy. The effects of dietary DHA on diabetic cardiomyopathy were evaluated in male Sprague-Dawley rats fed a reference diet rich in DHA, an HFD, or an HFD with added DHA for 16 weeks. Oxidative stress and lipotoxicity in rat heart tissue were assayed by Masson staining, immunohistochemistry, and TUNEL. ResultsIn vitro studies showed that dietary DHA reduced the occurrence of cardiomyopathy and improved cardiac responses to PA. In the rat model, dietary DHA reduced mitochondrial oxidative stress in HFD-induced diabetic cardiomyopathy. ConclusionDietary DHA reduced mitochondrial oxidative stress and ameliorated PA-induced lipid toxicity. DHA consumption may have had direct effects on cardiovascular risk via myocardial protection.

Effects of dietary docosahexaenoic acid on growth performance, fatty acid profile and lipogenesis of blunt snout bream ( Megalobrama amblycephala )

Six diets were designed to investigate the effects of dietary docosahexaenoic acid (22:6n‐3; DHA) levels (0.5, 1.3, 2.3, 4.2, 8.1 and 15.9 g/kg diets) on growth performance, fatty acid profile and expression of some lipogenesis‐related genes of blunt snout bream (Megalobrama amblycephala). Fish (average weight: 26.40 ± 0.11 g) were randomly fed one of six diets for 8 weeks. Results indicated that the final body weight (FBW) and specific growth rate (SGR) of fish fed 1.3 g/kg DHA were significantly higher than other groups except for the 2.3 g/kg DHA (p < .05). Compared with other groups, the number of lipid droplet clusters of the liver stained with oil red O in the 2.3 g/kg DHA group was the highest, which was consistent with the lipid contents of whole body and liver. The DHA proportion in liver and muscle significantly increased with the increasing dietary DHA levels (p < .05), which reflected fatty acid profiles of diets. The highest mRNA expressions of acetyl‐CoA carboxylase α (ACCα), fatty acid synthase (FAS) and sterol regulatory element‐binding protein‐1 (SREBP‐1) occurred in the 1.3 g/kg DHA group, followed by 2.3 g/kg DHA. In summary, the supplementation of 1.3–2.3 g/kg DHA could improve growth performance and lipogenesis, and the dietary DHA could improve DHA and PUFA proportion in liver and muscle.

Two weeks of docosahexaenoic acid (DHA) supplementation increases synthesis-secretion kinetics of n-3 polyunsaturated fatty acids compared to 8 weeks of DHA supplementation

Docosahexaenoic acid (DHA, 22:6n-3) must be consumed in the diet or synthesized from n-3 polyunsaturated fatty acid (PUFA) precursors. However, the effect of dietary DHA on the metabolic pathway is not fully understood. Presently, 21-day-old Long Evans rats were weaned onto one of four dietary protocols: 1) 8 weeks of 2% ALA (ALA), 2) 6 weeks ALA followed by 2 weeks of 2% ALA + 2% DHA (DHA), 3) 4 weeks ALA followed by 4 weeks DHA and 4) 8 weeks of DHA. After the feeding period, 2H5-ALA and 13C20-eicosapentaenoic acid (EPA, 20:5n-3) were co-infused and blood was collected over 3 h for determination of whole-body synthesis-secretion kinetics. The synthesis-secretion coefficient (ml/min, means ± SEM) for EPA (0.238±0.104 vs. 0.021±0.001) and DPAn-3 (0.194±0.060 vs. 0.020±0.008) synthesis from plasma unesterified ALA, and DPAn-3 from plasma unesterified EPA (2.04±0.89 vs. 0.163±0.025) were higher (P<.05) after 2 weeks compared to 8 weeks of DHA feeding. The daily synthesis-secretion rate (nmol/d) of DHA from EPA was highest after 4 weeks of DHA feeding (843±409) compared to no DHA (70±22). Liver gene expression of ELOVL2 and FADS2 were lower (P<.05) after 4 vs. 8 weeks of DHA. Higher synthesis-secretion kinetics after 2 and 4 weeks of DHA feeding suggests an increased throughput of the PUFA metabolic pathway. Furthermore, these findings may lead to novel dietary strategies to maximize DHA levels while minimizing dietary requirements.

Effect of dietary docosahexaenoic acid on rhodopsin content and packing in photoreceptor cell membranes

Docosahexaenoic acid (DHA) is enriched in photoreceptor cell membranes. DHA deficiency impairs vision due to photoreceptor cell dysfunction, which is caused, at least in part, by reduced activity of rhodopsin, the light receptor that initiates phototransduction. It is unclear how the depletion of membrane DHA impacts the structural properties of rhodopsin and, in turn, its activity. Atomic force microscopy (AFM) was used to assess the impact of DHA deficiency on membrane structure and rhodopsin organization. AFM revealed that signaling impairment in photoreceptor cells is independent of the oligomeric status of rhodopsin and causes adaptations in photoreceptor cells where the content and density of rhodopsin in the membrane is increased. Functional and structural changes caused by DHA deficiency were reversible.

DHA-supplemented diet increases the survival of rats following asphyxia-induced cardiac arrest and cardiopulmonary bypass resuscitation

Accumulating evidence illustrates the beneficial effects of dietary docosahexaenoic acid (DHA) on cardiovascular diseases. However, its effects on cardiac arrest (CA) remain controversial in epidemiological studies and have not been reported in controlled animal studies. Here, we examined whether dietary DHA can improve survival, the most important endpoint in CA. Male Sprague-Dawley rats were randomized into two groups and received either a control diet or a DHA-supplemented diet for 7–8 weeks. Rats were then subjected to 20 min asphyxia-induced cardiac arrest followed by 30 min cardiopulmonary bypass resuscitation. Rat survival was monitored for additional 3.5 h following resuscitation. In the control group, 1 of 9 rats survived for 4 h, whereas 6 of 9 rats survived in the DHA-treated group. Surviving rats in the DHA-treated group displayed moderately improved hemodynamics compared to rats in the control group 1 h after the start of resuscitation. Rats in the control group showed no sign of brain function whereas rats in the DHA-treated group had recurrent seizures and spontaneous respiration, suggesting dietary DHA also protects the brain. Overall, our study shows that dietary DHA significantly improves rat survival following 20 min of severe CA.

Effect of dietary docosahexaenoic acid (DHA) in phospholipids or triglycerides on brain DHA uptake and accretion

Tracer studies suggest that phospholipid DHA (PL-DHA) more effectively targets the brain than triglyceride DHA (TAG-DHA), although the mechanism and whether this translates into higher brain DHA concentrations are not clear. Rats were gavaged with [U-3H]PL-DHA and [U-3H]TAG-DHA and blood sampled over 6h prior to collection of brain regions and other tissues. In another experiment, rats were supplemented for 4weeks with TAG-DHA (fish oil), PL-DHA (roe PL) or a mixture of both for comparison to a low-omega-3 diet. Brain regions and other tissues were collected, and blood was sampled weekly. DHA accretion rates were estimated using the balance method. [U-3H]PL-DHA rats had higher radioactivity in cerebellum, hippocampus and remainder of brain, with no differences in other tissues despite higher serum lipid radioactivity in [U-3H]TAG-DHA rats. TAG-DHA, PL-DHA or a mixture were equally effective at increasing brain DHA. There were no differences between DHA-supplemented groups in brain region, whole-body, or tissue DHA accretion rates except heart and serum TAG where the PL-DHA/TAG-DHA blend was higher than TAG-DHA. Apparent DHA β-oxidation was not different between DHA-supplemented groups. This indicates that more labeled DHA enters the brain when consumed as PL; however, this may not translate into higher brain DHA concentrations.

139 Non-targeted lipidomics of stallion spermatozoa: Effect of dietary docosahexaenoic acid (DHA)

139 Non-targeted lipidomics of stallion spermatozoa: Effect of dietary docosahexaenoic acid (DHA)

Docosahexaenoic acid in Arctic charr (Salvelinus alpinus): the importance of dietary supply and physiological response during the entire growth period.

The aim of this 14-month feeding study was to investigate the effects of dietary docosahexaenoic acid (DHA) on tissue fatty acid composition, DHA retention, and DHA content per biomass accrual in muscle tissues of Arctic charr (Salvelinus alpinus). A control feed, formulated with a relatively high DHA inclusion level (F1), was compared with feeds containing gradually reduced amounts of DHA (Feeds F2, F3, and F4). Arctic charr were randomly distributed among 12 tanks and fed one of the feeds in triplicate. The DHA content within muscle tissues of fish fed diets F1 and F2 was generally higher compared to fish fed diets F3 and F4. However, there was an interaction between dietary DHA treatment and season, which resulted in fish muscle tissues having similar DHA contents irrespective of dietary supply during specific sampling periods. Although diets F3 and F4 contained ~4-fold less DHA compared to diets F1 and F2, the retention of DHA in dorsal and ventral muscle tissue was up to 5-fold higher relative to the diet content in fish fed diets F3 and F4. However, the difference among treatments was dependent on the month sampled. In addition, younger fish retained DHA more efficiently compared to older fish. DHA (μg DHA/g/day) accrual in muscle tissue was independent of somatic growth, and there was no difference among treatments. The results suggested that dietary DHA may be essential throughout the life cycle of Arctic charr and that the DHA content of muscle tissues was influenced by diet and metabolic/physiological factors, such as specific DHA retention during the entire growth cycle . Finally, this long-term feeding study in Arctic charr indicated a non-linear function in DHA retention in dorsal and ventral muscle tissues throughout the life cycle, which varied in its relationship to dietary DHA.

Docosahexaenoic acid in the goat kid diet: Effects on immune system and meat quality1

The effect of dietary docosahexaenoic acid (C22:6n3; DHA) supplementation on meat quality and immunity in goat (Capra hircus) kids was examined. Goat kids (n = 30) were fed 1 of 3 experimental diets: goat milk (GM), cow (Bos taurus) milk (CM), and CM supplemented with DHA (CM-DHA). Animals were fed ad libitum twice daily and weighed twice each week. Blood samples were collected by jugular venipuncture daily during the first 10 d of life and were subsequently collected every 5 d until slaughter at a BW of 8 kg. Carcass size (linear measurements) and weight, as well as meat pH, color, tenderness, and chemical composition were determined. Fatty acid profiles of intramuscular, peri-renal, pelvic, subcutaneous, and intermuscular fats were analyzed. Blood IgG and IgM concentrations, complement system activity (classical and alternative pathways), and chitotriosidase activity were recorded. Results indicated that the diet containing DHA did not affect (P > 0.05) carcass linear measurements, meat quality characteristics, or proximate composition of the meat. However, C22:6n3 fatty acid levels, mainly in intramuscular fat, were enriched (P < 0.05) in CM-DHA animals, and the n-6 to n-3 PUFA ratio was improved (P < 0.05). No differences (P > 0.05) in immune function were observed among groups. In conclusion, powdered whole CM is an effective option for feeding goat kids, and the inclusion of DHA to CM increases the quantity of this fatty acid in the meat.

Dietary Docosahexaenoic Acid Supplementation Prevents Age-Related Functional Losses and A2E Accumulation in the Retina

With age, retina function progressively declines and A2E, a constituent of the toxin lipofuscin, accumulates in retinal pigment epithelial (RPE) cells. Both events are typically exacerbated in age-related retina diseases. We studied the effect of dietary docosahexaenoic acid (DHA, C22:6n-3) supplementation on these events, using a transgenic mouse model (mutant human ELOVL4; E4) displaying extensive age-related retina dysfunction and massive A2E accumulation. Retina function was assessed with the electroretinogram (ERG) and A2E levels were measured in E4 and wildtype (WT) mice. Dietary DHA was manipulated from 1 to 3, 1 to 6, 6 to 12, and 12 to 18 months: 1% DHA over total fatty acids (E4+, WT+) or similar diet without DHA (E4-, WT-). Increased omega-3/6 ratios (DHA/arachidonic acid) in E4+ and WT+ retinas were confirmed for the 1- to 3-month and 1- to 6-month trials. Although 1- to 3-month intervention had no effects, when prolonged to 1 to 6 months, RPE function (ERG c-wave) was preserved in E4+ and WT+. Intervention from 6 to 12 months led to maintained outer and inner retina function (ERG a- and b-wave, respectively) in E4+. At 12 to 18 months, a similar beneficial effect on retina function occurred in WT+; A2E levels were reduced in E4+ and WT+. DHA supplementation was associated with: preserved retina function at mid-degenerative stages in E4 mice; prevention of age-related functional losses in WT mice; and reduced A2E levels in E4 and WT mice at the oldest age examined. These findings imply that dietary DHA could have broad preventative therapeutic applications (acting on pathologic and normal age-related ocular processes).

ELOVL4 protein preferentially elongates 20:5n3 to very long chain PUFAs over 20:4n6 and 22:6n3

We hypothesized that reduction/loss of very long chain PUFAs (VLC-PUFAs) due to mutations in the ELOngase of very long chain fatty acid-4 (ELOVL4) protein contributes to retinal degeneration in autosomal dominant Stargardt-like macular dystrophy (STGD3) and age-related macular degeneration; hence, increasing VLC-PUFA in the retina of these patients could provide some therapeutic benefits. Thus, we tested the efficiency of elongation of C20-C22 PUFA by the ELOVL4 protein to determine which substrates are the best precursors for biosynthesis of VLC-PUFA. The ELOVL4 protein was expressed in pheochromocytoma cells, while green fluorescent protein-expressing and nontransduced cells served as controls. The cells were treated with 20:5n3, 22:6n3, and 20:4n6, either individually or in equal combinations. Both transduced and control cells internalized and elongated the supplemented FAs to C22-C26 precursors. Only ELOVL4-expressing cells synthesized C28-C38 VLC-PUFA from these precursors. In general, 20:5n3 was more efficiently elongated to VLC-PUFA in the ELOVL4-expressing cells, regardless of whether it was in combination with 22:6n3 or with 20:4n6. In each FA treatment group, C34 and C36 VLC-PUFAs were the predominant VLC-PUFAs in the ELOVL4-expressing cells. In summary, 20:5n3, followed by 20:4n6, seems to be the best precursor for boosting the synthesis of VLC-PUFA by ELOVL4 protein.

DHA Supplemented in Peptamen Diet Offers No Advantage in Pathways to Amyloidosis: Is It Time to Evaluate Composite Lipid Diet?

Numerous reports have documented the beneficial effects of dietary docosahexaenoic acid (DHA) on beta-amyloid production and Alzheimer's disease (AD). However, none of these studies have examined and compared DHA, in combination with other dietary nutrients, for its effects on plaque pathogenesis. Potential interactions of DHA with other dietary nutrients and fatty acids are conventionally ignored. Here we investigated DHA with two dietary regimes; peptamen (pep+DHA) and low fat diet (low fat+DHA). Peptamen base liquid diet is a standard sole-source nutrition for patients with gastrointestinal dysfunction. Here we demonstrate that a robust AD transgenic mouse model shows an increased tendency to produce beta-amyloid peptides and amyloid plaques when fed a pep+DHA diet. The increase in beta-amyloid peptides was due to an elevated trend in the levels of beta-secretase amyloid precursor protein (APP) cleaving enzyme (BACE), the proteolytic C-terminal fragment beta of APP and reduced levels of insulin degrading enzyme that endoproteolyse beta-amyloid. On the contrary, TgCRND8 mice on low fat+DHA diet (based on an approximately 18% reduction of fat intake) ameliorate the production of abeta peptides and consequently amyloid plaques. Our work not only demonstrates that DHA when taken with peptamen may have a tendency to confer a detrimental affect on the amyloid plaque build up but also reinforces the importance of studying composite lipids or nutrients rather than single lipids or nutrients for their effects on pathways important to plaque development.

Effects of dietary docosahexaenoic acid (22:6n-3) and arachidonic acid (20:4n-6) on the growth, survival, stress resistance and fatty acid composition in black sea bass Centropristis striata (Linnaeus 1758) larvae

The objectives of this study were to determine the effects of the dietary docosahexaenoic acid (DHA) to arachidonic acid (ARA) ratio on the survival, growth, hypersaline stress resistance and tissue composition of black sea bass larvae raised from first feeding to metamorphic stages. Larvae were fed enriched rotifers Brachionus rotundiformis and Artemia nauplii containing two levels of DHA (0% and 10% total fatty acids=TFA) in conjunction with three levels of ARA (0%, 3% and 6% TFA). On d24ph, larvae fed the 10:6 (DHA:ARA) treatment showed significantly (P<0.05) higher survival (62.3%) than larvae fed 0:0 (DHA:ARA) (27.4%). Notochord length and dry weight were also significantly (P<0.05) greater in the 10:6 (DHA:ARA) treatment (8.65 mm, 2.14 mg) than in the 0:0 (DHA:ARA) (7.7 mm, 1.65 mg) treatment. During hypersaline (65 g L−1) challenge, no significant differences (P>0.05) were observed in the median survival time (ST50) between larvae fed 10% DHA (ST50=25.6 min) and larvae fed 0% DHA (ST50=18.2 min). The results suggested that black sea bass larvae fed prey containing 10% DHA with increasing ARA within the range of 0–6% showed improved growth and survival from first feeding through metamorphic stages.

Effect of dietary docosahexaenoic acid and soybean lecithin on spawning performance, egg and broodfish fatty acid and lipid class of striped knifejaw, Oplegnathus fasciatus

Effect of dietary docosahexaenoic acid and soybean lecithin on spawning performance, egg and broodfish fatty acid and lipid class of striped knifejaw, Oplegnathus fasciatus