Dietary Arachidonic Acid Supplementation Research Articles

Dietary arachidonic acid supplementation promoted cholesterol utilization, lipid deposition and molting for Scylla paramamosain

A six-week feeding trial was carried out to investigate the impact of dietary ARA and CHOL levels, and their interactions, on the growth, lipid metabolism, and molting response of juvenile mud crabs (Scylla paramamosain) with an initial weight of 17.46 ± 0.04 g. A 3 × 3 two-factor design was adopted for 9 experimental diets with 0%, 0.75% and 1.5% ARA levels and 0%, 0.75% and 1.5% CHOL supplemental levels, respectively. The results showed that ARA and CHOL had significant interaction effects on percent weight gain and specific growth rate. Percent weight gain and specific growth rate of crabs fed 0.75% ARA diet were significantly higher than those of crabs fed 0% ARA diet, but only when dietary CHOL content was 0.75%. ARA and CHOL levels had significant interaction on crude lipid content and percentage of Oil Red O staining area in the hepatopancreas, and when 0.75% ARA was supplemented to 0.75% CHOL diet, the levels of crude lipid and percentage of Oil Red O staining area in hepatopancreas were significantly up-regulated. Moreover, 0.75% CHOL diet that was supplemented with 0.75% ARA significantly up-regulated the levels of DHA, EPA, and ARA in the hepatopancreas. Additionally, significant interactions between ARA and CHOL were found in expression levels of genes related to long-chain polyunsaturated fatty acid anabolism (Δ9 fad, elovl4, elovl5 and elovl6), fatty acid anabolism and catabolism (aco3, cpt1 and acc), fatty acid transport (fabp1, fabp3 and fatp4), and lipid catabolism and anabolism (hsl, srebp1, lpl and hl) in the hepatopancreas. 1.5% dietary ARA significantly increased the content of serum T-CHO and the activity of hepatopancreatic LCAT. The addition of 1.5% dietary CHOL significantly reduced the concentration of 20E in the serum. Furthermore, both 0.75% and 1.5% dietary ARA reduced concentrations of MIH and CHH in the serum. Significant interactions between dietary ARA and CHOL were observed in the concentrations of 20E and MIH in the serum. Dietary ARA significantly increased the expression levels of dib, e74b, e75 and ftz-f1 in the hepatopancreas. In conclusion, adding 6.02–11.06 mg/kg ARA to 1.21–1.27 mg/kg CHOL diets or adding 6.04 mg/kg ARA to 6.17–7.02 mg/kg CHOL diets both promoted cholesterol metabolism, deposition of essential fatty acids and lipids, and activated ecr-mediated molting response pathway, with these positive benefits likely resulting from a significant increase in PG.

Effects of dietary arachidonic acid supplementation in low fishmeal and fish oil-free diets on growth performance, inflammatory response, gut histology, and non-specific immunity in sub-adult rainbow trout, Oncorhynchus mykiss

Arachidonic acid (ARA) is becoming increasingly important due to significant reductions in fishmeal (FM) and fish oil (FO), the primary sources of ARA, in aquafeeds. ARA is an essential omega-6 fatty acid in some fish species and plays a wide range of physiological roles. However, studies reported to date have demonstrated contrasting findings concerning the effects of ARA in fish growth and health, regardless of the fish's trophic level. Additionally, limited research has addressed energy allocation during reproduction and growth in sub-adult rainbow trout as they approach reproductive maturity. Therefore, a study was conducted to evaluate the effects of different levels of ARA on growth performance, the fatty acid composition of whole-body and ovary, intestinal inflammatory gene expression, gut histology, antioxidant activity, and non-specific immunity in sub-adult rainbow trout (Oncorhynchus mykiss). Four isonitrogenous (51% crude protein), isolipidic (15% crude lipid), and isocaloric (23 MJ/kg) diets were formulated and supplemented with ARA-enriched oil (40%), resulting in analyzed ARA levels of 0.10 (ARA0.10), 3.95 (ARA3.95), 7.67 ARA(7.67), and 14.8% (ARA14.8) of total fatty acid, respectively. Rainbow trout (307 ± 3.64 g) were fed to apparent satiation three times a day for 12 weeks to assess growth performance, feed utilization, and intestinal inflammatory response. The fish were then exposed to acute stress to evaluate circulating cortisol, prostaglandin E2, antioxidant activity, and non-specific immune response. The 12-week growth trial demonstrated that dietary ARA did not affect rainbow trout growth performance and feed utilization during the final grow-out. Whole-body fatty acid profiles reflected those of the diets except for eicosapentaenoic acid (EPA) content being significantly lower in the ARA14.8 group than in the ARA0.10 and ARA3.95 groups. EPA and docosahexaenoic acid (DHA) contents in the ovary were less affected by dietary ARA supplementation, likely reflecting the selective deposition of those fatty acids in embryonic development. The expression of tnf-α was significantly downregulated in ARA7.67 and ARA14.8 groups relative to other treatment groups, and only distal intestinal villus height was significantly increased in the ARA3.95 group, suggesting that dietary ARA supported intestinal health. Plasma superoxide dismutase, catalase, and lysozyme activity significantly increased in both pre- and post-stress groups due to incremental increases in dietary ARA. These results suggest that a moderate level of dietary ARA in low FM and FO-free enhances innate immune function and antioxidant responses while supporting intestinal health in sub-adult rainbow trout.

Dietary arachidonic acid affects the growth performance, fatty acid profile, immunity and resistance to heat stress in juvenile abalone Haliotis discus hannai Ino

A 93-day feeding trial was performed to evaluate the effects of dietary arachidonic acid (ARA) on the growth performance, antioxidative capacity, immunity and anti-stress capacity of juvenile abalone Haliotis discus hannai Ino with an initial mean body weight of 4.26 ± 0.11 g. Six practical diets with 0.04% (the control), 0.31%, 0.44%, 0.68%, 0.94% and 1.34% of ARA were designed. After the feeding trial, abalones were subjected to a heat stress test. The findings showed that the survival of abalone (91.7–96.7%) after the feeding trial was not significantly influenced by dietary ARA. The 0.31–0.44% of dietary ARA significantly increased the weight gain rate (WGR). The feed conversion ratio (FCR) was decreased by 0.31–0.68% of dietary ARA. The 0.44% of dietary ARA significantly enhanced the activity of trypsin, lipase and α-amylase in the intestine. Besides, dietary ARA supplementation significantly elevated the total antioxidative capacity and activity of superoxide dismutase, catalase and lysozyme in the cell-free hemolymph. Higher levels of dietary ARA (≥0.94%) significantly up-regulated the mRNA levels of nuclear factor κB, inhibitor of κBα and transcription factor AP-1 in the digestive gland. The 0.68% of dietary ARA significantly decreased the falling rate of abalone after heat stress. In conclusion, appropriate dietary ARA levels improved the growth performance and feed utilization of abalone. The optimal dietary ARA content for juvenile abalone was 0.52% based on the quadratic regression analysis of WGR. The 0.44–0.68% of dietary ARA improved the antioxidative capacity, immunity and anti-heat stress of abalone.

Effects of dietary arachidonic acid supplementation in high plant protein diets on growth, feed utilization, and immunity of olive flounder, Paralichthys olivaceus

This study was designed to evaluate the effects of graded levels of arachidonic acid (ARA) in low fish meal diets (30% fish meal, 30% plant protein blends) on growth, feed utilization, and immunity of olive flounder (Paralichthys olivaceus). The control diet was formulated with 3% fish oil and 5.1% soybean oil (ARA0.0). Five other diets were formulated incorporating different levels of ARA into the ARA0.0 diet at the expense of soybean oil; that is, 0.3, 0.6, 0.9, 1.2, and 1.5% ARA (ARA0.3, ARA0.6, ARA0.9, ARA1.2, and ARA1.5), respectively. Three replicate groups of fish (88.24 ± 0.06 g) were placed into 18 polyvinyl circular tanks (215 L), with 24 fish each and fed an experimental diet twice a day for nine weeks. Overall, significantly improved growth performance was observed in the ARA0.6 group. Liver C18:2n-6 was significantly reduced, and liver ARA content was significantly increased with the increase in dietary ARA levels. Nitroblue tetrazolium activity was significantly higher in the ARA0.6 group, and significantly higher superoxide dismutase and myeloperoxidase activities were observed in the ARA0.9 group. Further, immunoglobulin level and lysozyme activity were significantly improved in the ARA0.3 group, antiprotease activity was increased in the ARA0.6 and ARA0.9 groups, and the ARA0.3 group showed lower liver lipid content than the ARA0.0 group. Serum prostaglandin E2 level was significantly increased with 1.5% ARA inclusion. Pro-inflammatory gene expressions of interleukin (IL)-6, IL-8, IL-10, perforin, and tumor necrosis factor in the intestine were significantly downregulated, and anti-inflammatory gene expression of transforming growth factor-β2 gene expression was significantly upregulated with higher dietary ARA supplementation (0.9–1.5%). These results indicate that 0.3–0.9% supplemented ARA may improve the growth, immune, and hematological parameters of olive flounder.

Dietary arachidonic acid supplementation promotes the growth, steroidogenesis and ovarian development in mud crab Scylla paramamosain

A 22-week feeding experiment was executed to assess the impact of dietary ARA supplementation on the growth, tissue proximate composition, hemolymph biochemical, tissue fatty acids profile, ARA metabolite and sex steroid hormone, and the mRNA expression of ovarian development related gene of female mud crab in the pre-devolopmental stage. Crabs were fed with six diets containing different ARA levels (0.04%, 0.25%, 0.46%, 0.89%, 1.25%, and 1.57%, dry matter). The results showed that the increasing dietary ARA levels had significant effects on survival, percent weight gain (PWG), specific growth rate (SGR), and feed efficiency (FE), which showed an increasing trend initially and then showed a decreasing trend. According to the two-slope broken-line model and quadratic curve model for the relationship between PWG and dietary ARA levels, optimal dietary ARA levels were estimated to be 0.46% and 0.70%. The lipid contents in muscle and hepatopancreas decreased significantly with the increasing dietary ARA levels. Similarly, total cholesterol (T-CHO) and triglyceride (TG) concentrations were significantly decreased with the increasing dietary ARA levels. In the hepatopancreas and muscle, ARA contents significantly increased with the increasing dietary ARA levels. In hemolymph and hepatopancreas, progesterone (Prog), pregnenolone (Preg), estradiol (E2) and vitellogen (Vtg) concentrations presented earlier increase and later decrease trend. In the hepatopancreas, prostaglandin E2 (PGE2) and 5-hydroxyeicosatetraenoic acid (5-HETE) concentrations showed an upward trend. In the muscle, PGE2 concentration presented earlier increasing and later decreasing trend. In the ovary, the increasing dietary ARA levels produced similar effects on the expressions of genes, including steroidogenic acute regulatory protein (star), 3β-hydroxysteroid dehydrogenase (3βhsd), vitellogenin (vtg) and vitellogenin receptor (vtgr). Thus, moderate dietary ARA levels promoted growth, improved ARA deposition and metabolism, increased sex steroid hormone and Vtg levels, and enhanced ovarian development of female mud crab in the pre-developmental stage.

Dietary plant oil supplemented with arachidonic acid and eicosapentaenoic acid affects the fatty acid composition and eicosanoid metabolism of Atlantic salmon (Salmo salar L.) during smoltification

This study sought to investigate whether a “natural diet” (mimicking the fatty acid composition of freshwater aquatic insects eaten by salmon parr) during the freshwater (FW) life stage of pre-smolt Atlantic salmon (Salmo salar L.) affected red blood cells and gill fatty acid composition as well as eicosanoid metabolism in gill during smolting at different temperatures. Before being transferred to seawater (SW), salmon parr were fed with a modified (MO) diet containing vegetable oils (rapeseed, palm, and linseed oils) supplemented with eicosapentaenoic acid (EPA) and arachidonic acid (ARA) to completely replace the fish oil (FO). Fatty acid composition in red blood cells and gill tissues was determined before SW transfer and six weeks after. Additionally, the expression of genes associated with eicosanoid metabolism and Na+/K+-ATPase (NKA) activity in salmon gill was examined at different temperatures before SW transfer and 24 h after. The results showed the changes in fatty acid composition, including sum monounsaturated fatty acids (MUFAs), docosahexaenoic acid (DHA), ARA, EPA, and sum n-6 polyunsaturated fatty acids (n-6 PUFA) in both red blood cells and gill tissues at the FW stage were consistent with the fatty acid profiles of the supplied MO and FO fish diets; however sum EPA and DHA composition exhibited opposite trends to those of the FO diet. The proportion of ARA, EPA, and n-6 PUFA increased, whereas sum MUFAs and DHA decreased in the red blood cells and gill tissues of MO-fed fish compared to those fed with the FO diet at FW stage. Additionally, 5-lipoxygenase-activating protein (Flap) expression was downregulated in MO-fed fish prior to SW transfer. During the process of SW transfer at different temperatures, the MO diet remarkably suppressed NKAα1a expression in MO-fed fish both at 12 and 16 °C. The MO diet also upregulated phospholipase A2 group IV (PLA2g4) expression in gills at 8, 12, and 16 °C, but suppressed phospholipase A2 group VI (PLA2g6) expression in gills at 12 °C compared to FO-fed fish at 12 °C and MO-fed fish at 8 °C. The MO diet also upregulated Cyclooxygenase 2 (Cox-2) expression at 8 °C compared to FO-fed fish and increased Arachidonate 5-lipoxygenase (5-Lox) expression in MO-fed fish at 16 °C compared to both FO-fed fish at 16 °C and MO-fed fish at 8 °C. Our study also determined that both SW transfer water temperatures and diets during the FW period jointly influenced the mRNA expression of PLA2g4, PLA2g6, and Lpl, whereas 5-Lox was more sensitive to dietary changes. In conclusion, the MO diet affected the fatty acid composition in gill and in red blood cells. When transferred to SW, dietary ARA supplementation could promote the bioavailability for eicosanoid synthesis in gill mainly via PLA2g4 activation, and potentially inhibit the stress and inflammatory response caused by different water temperatures through dietary EPA supplementation.

Effects of dietary arachidonic acid on growth, immunity and intestinal microbiota of Litopenaeus vannamei under microcystin-LR stress

The harmful effects of microcystin-LR (MC-LR) stress are unavoidable in shrimp culture. Arachidonic acid (AA) is a fatty acid that regulates immune responses in aquatic animals. In this study, we investigated the effects of dietary AA on growth, immunity and intestinal microbiota of Litopenaeus vannamei under MC-LR stress. The shrimp were fed a control diet (non-supplemented with AA) or a AA diet (supplemented with 8.0 g/kg AA) for 56 days, followed by an acute MC-LR stress for 72 h. The results showed that dietary AA improved the growth and feed utilization of the shrimp. Microcystin-LR exposure increased the mRNA expressions of reactive oxygen species modulator 1 (ROMO1), glutathione peroxidase (GPx), caspase-3 (Casp-3), NADPH-cytochrome P450 reductase (NCPR) and sulfotransferase (SULT), but decreased that of catalase (CAT) and cytochrome C (Cytc). Dietary AA supplementation reversed the expressions of ROMO1, CAT, GPx and NCPR to the control level, but still maintained the higher levels of Cytc, Casp-3 and SULT than the control and MC-LR stress groups. Dietary AA could not effectively reverse the changes of intestinal microbial diversity, but it could improve intestinal microbial composition variation induced by MC-LR stress. Specially, dietary AA increased the relative abundances of beneficial bacteria Bacteroides and Lactobacillus, and reversed the changes of pathogenic bacteria Vibrio and Photobacterium induced by MC-LR stress to the control level. The changes of intestinal bacteria were correlated with immune gene expression. These results revealed that dietary AA had a positive effect on L. vannamei resistance to MC-LR stress by modulating immune response and intestinal microbial composition.

Parental dietary arachidonic acid altered serum fatty acid profile, hepatic antioxidant capacity, and lipid metabolism in domestic pigeons (Columba livia).

The aim of this study was to explore the effects of dietary arachidonic acid on serum fatty acid profile, hepatic antioxidant capacity, and lipid metabolism in pigeon squabs by supplementing arachidonic acid in their parental diets. A completely randomized design was conducted consisting of control group, 0.05% dietary arachidonic acid supplementation group, 0.1% dietary arachidonic acid supplementation group, and 0.2% dietary arachidonic acid supplementation group. Six randomly selected squabs from each group were sampled on Day 21 post-hatch. Results indicated that moderate level (0.05%) of arachidonic acid in parental diets for pigeon squabs improved lipid metabolism via regulation on serum lipid profile and fatty acid composition and tended to reduce hepatic lipid accumulation in the premise of negligible damage to antioxidant status. Unfortunately, excessive parental supplementation of dietary arachidonic acid might be harmful to squab health. The regulatory effects of arachidonic acid were sensitive to the arachidonic acid doses. In conclusion, parental dietary arachidonic acid at 0.05% could be beneficial for squabs to maintain health as reflective aspects in ameliorative serum lipid profile, fatty acid composition, and reduced hepatic lipid accumulation.

Dietary arachidonic acid supplementation improves the growth performance and alleviates plant protein‐based diet‐induced inflammation in juvenile turbot ( Scophthalmus maximus L.)

Dietary arachidonic acid supplementation improves the growth performance and alleviates plant protein‐based diet‐induced inflammation in juvenile turbot ( <i>Scophthalmus maximus</i> L.)

Intestinal homeostasis of juvenile tiger puffer Takifugu rubripes was sensitive to dietary arachidonic acid in terms of mucosal barrier and microbiota

A 74-day feeding trial was conducted to investigate the effects of different levels of dietary arachidonic acid (ARA) on mucosal barrier and microbiota in the intestine of tiger puffer Takifugu rubripes. Three isonitrogenous and isolipidic experimental diets were formulated to contain different ARA levels, i.e., 0.33 (Control), 2.45 (L-ARA), and 23.41 (H-ARA) g kg−1 dry matter. Each diet was fed to triplicate tanks. The results showed that the integrity of intestinal epithelial cells was impaired by increasing ARA levels. The leucocyte infiltration in the lamina propria was also enhanced by dietary ARA supplementation. Compared to the control group, group H-ARA had significantly down-regulated gene expression of intestinal tight junction proteins (claudin-4, claudin-7 and zonula occludens-1), but significantly up-regulated expression of myosin light chain kinase (MLCK). Gene expression of claudin-7 was significantly down-regulated also in group L-ARA. The intestinal lysozyme activity significantly decreased with increasing dietary ARA levels. Compared to the Control, diet H-ARA significantly up-regulated the gene expression of the pro-inflammatory cytokines tumor necrosis factor alpha (TNF-α) and interleukin 8 (IL-8), and down-regulated that of anti-inflammatory cytokines transforming growth factor-β1 (TGF-β1) in the hind intestine. Intestinal gene expression of Toll-like receptor 3 (TLR-3) and nuclear factor kappa B p100 (NF-κB p100) was significantly up-regulated by H-ARA. Sequencing of bacterial 16 s rRNA V4 region showed that Proteobacteria, Tenericutes and Firmicutes were dominant in the intestine of tiger puffer. Fish fed diet H-ARA showed significantly decreased alpha diversity of microbiota and increased relative abundance of Arcobacter, a potential pathogenic genus. These results suggested that dietary ARA tended to induce the dysfunction of intestinal mucosal barrier and modulate the intestinal bacterial community, and MLCK and TLR3/NF-κB signaling were possibly involved in these processes. The ARA content in diets for tiger puffer needs to be carefully managed considering the intestinal sensitivity to dietary ARA of this fish.

Effect of dietary arachidonic acid supplementation on acute muscle adaptive responses to resistance exercise in trained men: a randomized controlled trial.

Arachidonic acid (ARA), a polyunsaturated ω-6 fatty acid, acts as precursor to a number of prostaglandins with potential roles in muscle anabolism. It was hypothesized that ARA supplementation might enhance the early anabolic response to resistance exercise (RE) by increasing muscle protein synthesis (MPS) via mammalian target of rapamycin (mTOR) pathway activation and/or the late anabolic response by modulating ribosome biogenesis and satellite cell expansion. Nineteen men with ≥1 yr of resistance-training experience were randomized to consume either 1.5 g daily ARA or a corn-soy-oil placebo in a double-blind manner for 4 wk. Participants then undertook fasted RE (8 sets each of leg press and extension at 80% 1-repetition maximum), with vastus lateralis biopsies obtained before exercise, immediately postexercise, and at 2, 4, and 48 h of recovery. MPS (measured via stable isotope infusion) was not different between groups ( P = 0.212) over the 4-h recovery period. mTOR pathway members p70 S6 kinase and S6 ribosomal protein were phosphorylated postexercise ( P < 0.05), with no difference between groups. 45S preribosomal RNA increased 48 h after exercise only in ARA ( P = 0.012). Neural cell adhesion molecule-positive satellite cells per fiber increased 48 h after exercise ( P = 0.013), with no difference between groups ( P = 0.331). Prior ARA supplementation did not alter the acute anabolic response to RE in previously resistance-trained men; however, at 48 h of recovery, ribosome biogenesis was stimulated only in the ARA group. The findings do not support a mechanistic link between ARA and short-term anabolism, but ARA supplementation in conjunction with resistance training may stimulate increases in translational capacity. NEW & NOTEWORTHY Four weeks of daily arachidonic acid supplementation in trained men did not alter their acute muscle protein synthetic or anabolic signaling response to resistance exercise. However, 48 h after exercise, men supplemented with arachidonic acid showed greater ribosome biogenesis and a trend toward greater change in satellite cell content. Chronic arachidonic acid supplementation does not appear to regulate the acute anabolic response to resistance exercise but may augment muscle adaptation in the following days of recovery.

Arachidonic acid supplementation modulates blood and skeletal muscle lipid profile with no effect on basal inflammation in resistance exercise trained men

Arachidonic acid (ARA), an omega-6 polyunsaturated fatty acid (PUFA), is the metabolic precursor to the eicosanoid family of lipid mediators. Eicosanoids have potent pro-inflammatory actions, but also act as important autocrine/paracrine signaling molecules in skeletal muscle growth and development. Whether dietary ARA is incorporated into skeletal muscle phospholipids and the resulting impact on intramuscular inflammatory and adaptive processes in-vivo is not known. In the current study, resistance trained men (≥1 year) received dietary supplementation with 1.5g/day ARA (n=9, 24 ± 1.5 years) or placebo (n=10, 26 ± 1.3 years) for 4-weeks while continuing their normal training regimen. Plasma and vastus lateralis muscle biopsies were collected in an overnight fasted state at baseline and week 4. ARA supplementation increased plasma content of ARA and gamma-linolenic acid, while decreasing relative abundance of linoleic acid, eicosapentaenoic acid, and dihomo-gamma-linolenic acid. In skeletal muscle, ARA and dihomo-gamma-linolenic acid content increased, whereas alpha-linolenic-acid was reduced. Compared to placebo, ARA supplementation reduced circulating platelet and monocyte number, and decreased the mRNA expression of the immune cell surface markers; neutrophil elastase/CD66b and interleukin 1-beta, in peripheral blood mononuclear cells. In muscle, ARA supplementation increased mRNA expression of the myogenic regulatory factors; MyoD and myogenin, but had no effect on a range of immune cell markers or inflammatory cytokines. These data show that dietary ARA supplementation can rapidly and safely modulate plasma and muscle fatty acid profile and promote myogenic gene expression in resistance trained men, without a risk of increasing basal systemic or intramuscular inflammation.

Arachidonic acid in diets for early maturation stages enhances the final reproductive performances of Pacific white shrimp (Litopenaeus vannamei)

A 70-day feeding trial with Pacific white shrimp (Litopenaeus vannamei) broodstocks was conducted before eyestalk ablation to investigate the effects of arachidonic acid (ARA) in diets for early maturation stages on the final reproductive performances. Three isonitrogenous and isolipidic experimental diets were formulated to contain different ARA levels: the control diet without ARA supplementation (C, 0.87% ARA of total fatty acids (TFA)) and two diets with low (4.65% of TFA, ARA-L) or high ARA (12.39% of TFA, ARA-H) supplementation level. The diets were randomly assigned to 9 tanks of eight-month-old Pacific white shrimp broodstock (30 females and 30 males in each tank). Shrimp were reared in a flowing seawater system and fed to apparent satiation four times daily. At the end of the feeding trial, unilateral eyestalk of the females was ablated to stimulate the gonad maturation. Following the feeding trial (Period I) was a 28-day reproductive evaluation period (Period II), during which all shrimps were fed the same fresh invertebrate ingredients (a mixture of squid and polychaetes). Tissues samples of females were collected at the end of the feeding trial (Period I) and before spawning (ready to spawn) at the reproductive evaluation period (Period II) respectively to measure the gonadosomatic index (GI), hepatopancreas index (HI), estradiol level, and fatty acid composition. The spawning performance and quality of egg and larvae were assayed at Period II. The results showed that compared to the control group, ARA-L increased the GI at Period II while the ARA supplemented diets increased the estradiol synthesis at Period I. The HI was not influenced by dietary ARA level. Compared to the control group, ARA-L but not ARA-H significantly increased the spawning rate, multi-spawning rate, average spawning frequency and fecundity of female shrimp, diameter of fertilized egg, and crude metamorphosis rate of nauplii at 33h post spawning. The hatching rate significantly ranked as follows: C<ARA-H<ARA-L. The dietary ARA supplementation significantly improved the duration of nauplius and zoea larvae in the challenge test with low salinity. The experimental diets significantly affected the fatty acid compositions in hepatopancreas and ovaries of female shrimp, as well as those in fertilized eggs. In conclusion, these results suggested that the ARA supplementation in the diets for early maturation stages enhanced the final reproductive performances of Pacific white shrimp.

Cloning and characterization of fatty acid transport proteins in Japanese seabassLateolabrax japonicus, and their gene expressions in response to dietary arachidonic acid

In this study, putative cDNA of three fatty acid transport protein (FATP) isoforms, that is FATP1, FATP4 and FATP6, was cloned and characterized from the liver of Japanese seabass (Lateolabrax japonicus), and their expression in response to diets with different arachidonic acid (ARA) levels (0.05%, 0.22%, 0.37%, 0.60%, 1.38% and 2.32% of dry matter) was investigated through a feeding trial. Two subtypes of FATP1, that is FATP1a and FATP1b, were cloned for the first time. The Japanese seabass FATPs showed high identity to their orthologs in other fish species and mammals, but Japanese seabass FATP6 showed low identity to Japanese seabass FATP1 and FATP4. FATP1a gene was highly expressed in brain, liver and eye, whereas FATP1b had the highest gene expression in gill, followed by kidney, skin, eye, muscle and heart. FATP4 gene was primarily expressed in intestine, brain and eye. However, FATP6 had very low gene expression levels in almost all tissues. High levels of dietary ARA (0.60%~2.32%) enhanced the gene expressions of FATP1a and FATP4 in the intestine and the gene expression of FATP1a in the muscle, whereas the dietary ARA supplementation reduced the FATP1b mRNA expression in the liver. The gene expression of FATP1a, FATP4 and FATP6 in the liver, as well as the FATP4 gene expression in the muscle, was not significantly affected by dietary ARA levels. To our knowledge, this is the first study investigating the regulation of FATP gene expressions by dietary ARA.

Dietary arachidonic acid differentially regulates the gonadal steroidogenesis in the marine teleost, tongue sole (Cynoglossus semilaevis), depending on fish gender and maturation stage

A 3-month feeding trial with tongue sole Cynoglossus semilaevis broodstock was conducted before and during the spawning season to investigate the effects of dietary arachidonic acid (ARA) on the production of sex steroid hormones and gonadal gene expression of key proteins in steroidogenesis. Three isonitrogenous and isolipidic experimental diets were formulated to contain different ARA levels: the control diet without ARA supplementation (C, 0.58% ARA of total fatty acids (TFA)) and two diets with low (5.14% of TFA, ARA-L) or high ARA (15.44% of TFA, ARA-H) supplementation. The diets were randomly assigned to 9 tanks of 3-year-old tongue sole (10 females and 15 males in each tank). Fish were reared in a flowing seawater system and fed to apparent satiation twice daily. At the end of the feeding trial, tissue samples from mature females (MF, with spontaneous ovulation), immature females (IMF, early vitellogenesis), and mature males (MM, expressing milt) were collected to assay the production of sex steroid hormones, gonadal gene expression of sex steroid-synthesizing proteins, as well as the fatty acid profiles of gonad, liver and muscle lipids. Results showed that ARA supplementation significantly reduced the estradiol production in females, but stimulated the testosterone production in males. ARA supplementation significantly reduced the mRNA expression of aromatase in ovaries but significantly increased the gene expression of 3β-hydroxysteroid dehydrogenase (3β-HSD) in testes. In mature ovaries, diet ARA-L significantly reduced the gene expression of follicle stimulating hormone receptor (FSHR), 3β-HSD, and 17β-HSD; however, in immature ovaries, it significantly increased the gene expression of FSHR, steroidogenic acute regulatory protein (StAR), cholesterol side-chain cleavage enzyme (P450ssc), 3β-HSD, and 17β-HSD. In all gonads, 17α-hydroxylase (P450c17) responded to dietary ARA differently from other sex steroid-synthesizing proteins. ARA was preferentially accumulated in tongue sole gonad lipids. ARA concentrations were highest in gonad, liver and muscle lipids of MM fish and lowest in MF fish. Compared to female tongue sole, males had higher DHA concentrations in gonad lipids, but lower concentrations in liver lipids. In conclusion, results suggest dietary ARA regulates sex steroid hormone synthesis in tongue sole broodstock, and accumulates in gonad lipids, depending on both fish gender and maturation stage. Dietary ARA supplementation appears more important for male fish than for female fish, and more important for immature females than for mature females. Statement of relevanceThis study is beneficial to the broodstock diet formulation.

A New Model to Study the Role of Arachidonic Acid in Colon Cancer Pathophysiology.

A significant increase in cyclooxygenase 2 (COX2) gene expression has been shown to promote cylcooxygenase-dependent colon cancer development. Controversy associated with the role of COX2 inhibitors indicates that additional work is needed to elucidate the effects of arachidonic acid (AA)-derived (cyclooxygenase and lipoxygenase) eicosanoids in cancer initiation, progression, and metastasis. We have recently developed a novel Fads1 knockout mouse model that allows for the investigation of AA-dependent eicosanoid deficiency without the complication of essential fatty acid deficiency. Interestingly, the survival rate of Fads1-null mice is severely compromised after 2 months on a semi-purified AA-free diet, which precludes long-term chemoprevention studies. Therefore, in this study, dietary AA levels were titrated to determine the minimal level required for survival, while maintaining a distinct AA-deficient phenotype. Null mice supplemented with AA (0.1%, 0.4%, 0.6%, 2.0%, w/w) in the diet exhibited a dose-dependent increase (P < 0.05) in AA, PGE2, 6-keto PGF1α, TXB2, and EdU-positive proliferative cells in the colon. In subsequent experiments, null mice supplemented with 0.6% AA diet were injected with a colon-specific carcinogen (azoxymethane) in order to assess cancer susceptibility. Null mice exhibited significantly (P < 0.05) reduced levels/multiplicity of aberrant crypt foci (ACF) as compared with wild-type sibling littermate control mice. These data indicate that (i) basal/minimal dietary AA supplementation (0.6%) expands the utility of the Fads1-null mouse model for long-term cancer prevention studies and (ii) that AA content in the colonic epithelium modulates colon cancer risk. Cancer Prev Res; 9(9); 750-7. ©2016 AACR.

N-methyl-N-nitrosourea-induced cerebellar hypoplasia in rats: Effect of arachidonic acid supplementation during the gestational, lactational and post-weaning periods

Arachidonic acid (AA) is a fatty acid that is important for visual and brain development and is commonly added as a functional food ingredient to commercial infant formulas worldwide. However, few studies have examined whether AA supplementation during neonatal life has an effect on neuronal abnormalities. In the present study, the effect of dietary AA supplementation in dams during gestation and lactation was investigated by examining N-methyl-N-nitrosourea (MNU)-induced cerebellar hypoplasia in young Lewis rats. Dams were fed a 2.0% AA diet or a basal diet (<0.01% AA). At birth (postnatal day 0), male and female pups received a single intraperitoneal injection of 35 mg/kg MNU or vehicle. Brain weights were measured and a morphological analysis of macroscopic and histological specimens was conducted after 7, 14, 21, 28 and 60 days. Irrespective of whether the rats had been fed an AA diet, the brain weights of the MNU-treated rats, particularly the weights of the cerebellum, were decreased compared with those of the MNU-untreated rats from the 14th day following the MNU injection. Macroscopic reductions in the cerebellar length and/or width and histologically observed reductions in cerebellar vertex height and/or cortex width were also detected in the MNU-treated rats, irrespective of whether the rats had been fed with AA. Histopathologically, the MNU-treated rats (irrespective of AA supplementation) exhibited disorganization of the cerebellar cortex and disarrangement of the cortical layers (loss and/or disturbance of the molecular, Purkinje and granular cell layers). There were no significant differences in any parameters among the MNU-treated rats, irrespective of whether the rats had been fed an AA diet. In conclusion, an AA-rich diet for dams during gestation and lactation did not modify MNU-induced cerebellar hypoplasia in their offspring.

Arachidonic acid supplementation does not affect N-methyl-N-nitrosourea-induced renal preneoplastic lesions in young Lewis rats

Arachidonic acid (AA) is naturally found in human breast milk. AA, together with docosahexaenoic acid, is commonly added as a functional food ingredient to commercial infant formula worldwide, in accordance with the international standards of Codex Alimentarius. However, few studies of the possible renal carcinogenic effects of AA supplementation during neonatal life have been performed. The effect of dietary AA supplementation in dams during gestation and lactation was investigated on N-methyl-N-nitrosourea (MNU)-induced preneoplastic lesions in the kidneys of young Lewis rats. Dams were fed a 2.0% AA diet or a basal diet (<0.01% AA). At birth (postnatal day 0), male and female pups received a single intraperitoneal injection of 35 mg/kg MNU or vehicle. Renal morphology was examined after 7, 14, 21, 28 and 60 days. Histopathologically, renal preneoplastic lesions, such as nephroblastomatosis and mesenchymal cell proliferation, were found on day 60 in both the MNU-treated groups. There was no significant difference in lesion incidence of 38% in the basal diet group and 31% in the AA diet group. In conclusion, an AA-rich diet for dams during gestation and lactation does not modify MNU-induced renal preneoplastic lesions in their offspring.

Promoting effect of arachidonic acid supplementation on N-methyl-N-nitrosourea-induced pancreatic acinar cell hyperplasia in young Lewis rats.

Arachidonic acid (AA) is naturally found in human breast milk. AA, together with docosahexaenoic acid, is commonly added as a functional food ingredient to commercial infant formula worldwide, in accordance with the international standard of Codex Alimentarius. However, few studies have been performed that are concerned with the possible carcinogenic effects of AA supplementation during neonatal life. The effect of dietary AA supplementation in dams, during gestation and lactation, was investigated in N-methyl-N-nitrosourea (MNU)-induced preneoplastic lesions in the exocrine pancreas of young Lewis rats. Dams were fed either an AA (2.0% AA) or a basal (<0.01% AA) diet. On postnatal day 0 (at birth), male and female pups received a single intraperitoneal injection of either 35 mg/kg MNU or vehicle. The morphology and proliferating activity of the exocrine pancreas were examined by proliferative cell nuclear antigen immunohistochemistry 7, 14, 21, 28 and/or 60 days post-MNU. Histopathologically, acinar cell hyperplasia (ACH) occurred in the MNU-treated groups 60 days after MNU injection, irrespecitive of whether the rats had been fed an AA diet. Morphometrically, the number and area of ACH per 1 mm(2) in MNU-treated rats increased significantly in the AA diet-fed rats, compared with basal diet-fed rats. The number of proliferative cell nuclear antigen-positive acinar cells in both the normal and hyperplastic areas of MNU-treated rats increased significantly in the AA diet-fed rats. In conclusion, providing dams with an AA-rich diet during gestation and lactation promotes MNU-induced pancreatic ACH in young Lewis rats.

Effect of Arachidonic Acid-enriched Oil Diet Supplementation on the Taste of Broiler Meat.

To elucidate the relationship between the arachidonic acid (AA) content and the taste of broiler meat, the effects of AA-enriched oil (AAO) supplements on the fatty acid content and sensory perceptions of thigh meat were evaluated. Four types of oil, including corn oil (CO), a 1:1 mixture of AAO and palm oil (PO) (1/2 AAO), a 1:3 mixture of AAO and PO (1/4 AAO), and a 1:7 mixture of AAO and PO (1/8 AAO) were prepared. Each type of oil was mixed with silicate at a ratio of 7:3, and added to the diet at a final proportion of 5% of fresh matter. Broiler chickens were fed these diets for 1 wk before slaughter. In thigh meat, the AA content of the 1/2 and 1/4 AAO groups was significantly higher than that of the CO group. The AA content in thigh meat (y, mg/g) increased linearly with increasing dietary AAO content (x, g/100 g of diet), according to the equation y = 0.5674+0.4596× (r2 = 0.8454). The content of other fatty acids was not significantly different among the 4 diet groups. Sensory evaluation showed that the flavor intensity, umami (L-glutamate taste), kokumi (continuity, mouthfulness, and thickness), and aftertaste of the 1/2 and 1/4 AAO groups were significantly higher than that of the CO group. There were significant positive correlations between AA content in thigh meat and the flavor intensity, total taste intensity, umami, and aftertaste. These data suggest that the taste of broiler meat can be improved by the amount of dietary AA supplementation.