n-3脂肪酸代谢产物抗炎作用的研究进展

炎症反应是机体正常组织对感染和损伤的应答,然而过度的炎症反应往往会引起急性和慢性疾病的发生.最近研究发现,由n-3多不饱和脂肪酸二十碳五烯酸和二十二碳六烯酸代谢产生的resolvins和protectins两类化合物,具有很强的抗炎和炎症修复活性.综述了resolvins和protectin D1的来源、抗炎作用和抗炎机制,为进一步开展n-3多不饱和脂肪酸及其代谢产物的抗炎作用研究、为炎症的防治提供新的思路.     

Eicosapentaenoic acid decreases expression of anandamide synthesis enzyme and cannabinoid receptor 2 in osteoblast-like cells

Anandamide (AEA) is an endogenous agonist for the cannabinoid receptor 2 (CB2) which is expressed in osteoblasts. Arachidonic acid (AA) is the precursor for AEA and dietary n-3 polyunsaturated fatty acids (PUFA) are known to reduce the concentrations of AA in tissues and cells. Therefore, we hypothesized that n-3 PUFA, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which reduce AA in cells, could lower AEA in osteoblasts by altering enzyme expression of the endocannabinoid (EC) system. MC3T3-E1 osteoblast-like cells were grown for 6, 10, 15, 20, 25 or 30 days in osteogenic medium. Osteoblasts were treated with 10 μM of AA, EPA, DHA, oleic acid (OA) or EPA+DHA (5 μM each) for 72 h prior to their collection for measurement of mRNA and alkaline phosphatase (ALP) activity. Compared to vehicle control, osteoblasts treated with AA had higher levels of AA and n-6 PUFA while those treated with EPA and DHA had lower n-6 but higher n-3 PUFA. Independent of the fatty acid treatments, osteoblasts matured normally as evidenced by ALP activity. N-acyl phosphatidylethanolamine-selective phospholipase D (NAPE-PLD), fatty acid amide hydrolase (FAAH) and CB2 mRNA expression were higher at 20 days compared to 10 days. NAPE-PLD and CB2 mRNA was lower in osteoblasts treated with EPA compared to all other groups. Thus, mRNA expression for NAPE-PLD, FAAH, and CB2 increased during osteoblast maturation and EPA reduced mRNA for NAPE-PLD and CB2 receptor. In conclusion, EPA lowered mRNA levels for proteins of the EC system and mRNA for AEA synthesis/degradation is reported in osteoblasts.     

Paradigm shift – Metabolic transformation of docosahexaenoic and eicosapentaenoic acids to bioactives exemplify the promise of fatty acid drug discovery

Fatty acid drug discovery (FADD) is defined as the identification of novel, specialized bioactive mediators that are derived from fatty acids and have precise pharmacological/therapeutic potential. A number of reports indicate that dietary intake of omega-3 fatty acids and limited intake of omega-6 promotes overall health benefits. In 1929, Burr and Burr indicated the significant role of essential fatty acids for survival and functional health of many organs. In reference to specific dietary benefits of differential omega-3 fatty acids, docosahexaenoic and eicosapentaenoic acids (DHA and EPA) are transformed to monohydroxy, dihydroxy, trihydroxy, and other complex mediators during infection, injury, and exercise to resolve inflammation. The presented FADD approach describes the metabolic transformation of DHA and EPA in response to injury, infection, and exercise to govern uncontrolled inflammation. Metabolic transformation of DHA and EPA into a number of pro-resolving molecules exemplifies a novel, inexpensive approach compared to traditional, expensive drug discovery. DHA and EPA have been recommended for prevention of cardiovascular disease since 1970. Therefore, the FADD approach is relevant to cardiovascular disease and resolution of inflammation in many injury models. Future research demands identification of novel action targets, receptors for biomolecules, mechanism(s), and drug-interactions with resolvins in order to maintain homeostasis.     

Dietary Effects of Eicosapentaenoic and Docosahexaenoic Acid Esters on Lipid Metabolism and Immune Parameters in Sprague-Dawley Rats

Sprague-Dawley rats were fed eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) ethyl esters at the 2% level for 3 weeks to clarify their effects on immune functions. In the rats fed EPA or DHA, serum cholesterol, triglyceride, and phospholipid (PL) levels were significantly lower than those in the rats fed safflower oil. In PL fractions of serum, liver, lung, splenocytes, and peritoneal exudate cells (PEC), increases in linoleic and dihomo-γ-linolenic acid contents and a decrease in arachidonic acid (AA) content were observed in the rats fed EPA or DHA. In addition, the EPA content increased in the rats fed EPA and DHA. In the rats fed EPA or DHA, a decrease of LTB₄ productivity and an increase of LTB₅ productivity were observed in the PEC, in response to the treatment with 5 μM calcium ionophore A23187 for 20 min. The changes in leukotriene production were more marked in EPA-fed rats than in DHA-fed rats. These results suggest that dietary EPA affects lipid metabolism and leukotriene synthesis more strongly than DHA.     

Regulation of rat brain polyunsaturated fatty acid (PUFA) metabolism during graded dietary n-3 PUFA deprivation

Knowing threshold changes in brain lipids and lipid enzymes during dietary n-3 polyunsaturated fatty acid deprivation may elucidate dietary regulation of brain lipid metabolism. To determine thresholds, rats were fed for 15 weeks DHA-free diets having graded reductions of α-linolenic acid (α-LNA). Compared with control diet (4.6% α-LNA), plasma DHA fell significantly at 1.7% dietary α-LNA while brain DHA remained unchanged down to 0.8% α-LNA, when plasma and brain docosapentaenoic acid (DPAn-6) were increased and DHA-selective iPLA₂ and COX-1 activities were downregulated. Brain AA was unchanged by deprivation, but AA selective-cPLA₂, sPLA₂ and COX-2 activities were increased at or below 0.8% dietary α-LNA, possibly in response to elevated brain DPAn-6. In summary, homeostatic mechanisms appear to maintain a control brain DHA concentration down to 0.8% dietary DHA despite reduced plasma DHA, when DPAn-6 replaces DHA. At extreme deprivation, decreased brain iPLA₂ and COX-1 activities may reduce brain DHA loss.     

The relationship between the fatty acid composition of immune cells and their function

The immune system, including its inflammatory components, is fundamental to host defence against pathogenic invaders. It is a complex system involving interactions amongst many different cell types dispersed throughout the body. Central to its actions are phagocytosis of bacteria, processing of antigens derived from intracellular and extracellular pathogens, activation of T cells with clonal expansion (proliferation) and production of cytokines that elicit effector cell functions such as antibody production and killing cell activity. Inappropriate immunologic activity, including inflammation, is a characteristic of many common human disorders. Eicosanoids produced from arachidonic acid have roles in inflammation and regulation of T and B lymphocyte functions. Eicosapentaenoic acid (EPA) also gives rise to eicosanoids and these may have differing properties from those of arachidonic acid-derived eicosanoids. EPA and docosahexaenoic acid (DHA) give rise to newly discovered resolvins which are anti-inflammatory and inflammation resolving. Human immune cells are typically rich in arachidonic acid, but arachidonic acid, EPA and DHA contents can be altered through oral administration of EPA and DHA. This results in a changed pattern of production of eicosanoids and probably also of resolvins, although the latter are not well examined in the human context. Changing the fatty acid composition of immune cells also affects phagocytosis, T cell signaling and antigen presentation capability. These effects appear to mediated at the membrane level suggesting important roles of fatty acids in membrane order, lipid raft structure and function, and membrane trafficking. Thus, the fatty acid composition of human immune cells influences their function and the cell membrane contents of arachidonic acid, EPA and DHA are important. Fatty acids influence immune cell function through a variety of complex mechanisms and these mechanisms are now beginning to be unraveled.     

Arachidonic acid and docosahexaenoic acid suppress thrombin-evoked Ca2+ response in rat astrocytes by endogenous arachidonic acid liberation

Arachidonic (AA) and docosahexaenoic acid (DHA) are the major polyunsaturated fatty acids (PUFAs) in the brain. However, their influence on intracellular Ca2+ signalling is still widely unknown. In astrocytes, the amplitude of thrombin- induced Ca2+ response was time-dependently diminished by AA and DHA, or by the AA tetraynoic analogue ETYA, but not by eicosapentaenoic acid (EPA). Thrombin-elicited Ca2+ response was reduced (20-30%) by 1-min exposure to AA or DHA. Additionally, 1-min application of AA or DHA together with thrombin in Ca2+-free medium blocked Ca2+ influx, which followed after readdition of extracellular Ca2+. EPA and ETYA, however, were ineffective. Long-term treatment of astrocytes with AA and DHA, but not EPA reduced the amplitude of the thrombin-induced Ca2+ response by up to 80%. AA and DHA caused a comparable decrease in intracellular Ca2+ store content. Only DHA and AA, but not EPA or ETYA, caused liberation of endogenous AA by cytosolic phospholipase A2 (cPLA2). Therefore, we reasoned that the suppression of Ca2+ response to thrombin by AA and DHA could be due to release of endogenous AA. Possible participation of AA metabolites, however, was excluded by the finding that specific inhibitors of the different oxidative metabolic pathways of AA were not able to abrogate the inhibitory AA effect. In addition, thrombin evoked AA release via activation of cPLA2. From our data we propose a novel model of positive/negative-feed-back in which agonist-induced release of AA from membrane phospholipids promotes further AA release and then suppresses agonist-induced Ca2+ responses.     

The role of prostacyclin synthase and thromboxane synthase signaling in the development and progression of cancer

Prostacyclin synthase and thromboxane synthase signaling via arachidonic acid metabolism affects a number of tumor cell survival pathways such as cell proliferation, apoptosis, tumor cell invasion and metastasis, and angiogenesis. However, the effects of these respective synthases differ considerably with respect to the pathways described. While prostacyclin synthase is generally believed to be anti-tumor, a pro-carcinogenic role for thromboxane synthase has been demonstrated in a variety of cancers. The balance of oppositely-acting COX-derived prostanoids influences many processes throughout the body, such as blood pressure regulation, clotting, and inflammation. The PGI₂/TXA₂ ratio is of particular interest in-vivo, with the corresponding synthases shown to be differentially regulated in a variety of disease states. Pharmacological inhibition of thromboxane synthase has been shown to significantly inhibit tumor cell growth, invasion, metastasis and angiogenesis in a range of experimental models. In direct contrast, prostacyclin synthase overexpression has been shown to be chemopreventive in a murine model of the disease, suggesting that the expression and activity of this enzyme may protect against tumor development.     

An Integrated Model of Eicosanoid Metabolism and Signaling Based on Lipidomics Flux Analysis

There is increasing evidence for a major and critical involvement of lipids in signal transduction and cellular trafficking, and this has motivated large-scale studies on lipid pathways. The Lipid Metabolites and Pathways Strategy consortium is actively investigating lipid metabolism in mammalian cells and has made available time-course data on various lipids in response to treatment with KDO₂-lipid A (a lipopolysaccharide analog) of macrophage RAW 264.7 cells. The lipids known as eicosanoids play an important role in inflammation. We have reconstructed an integrated network of eicosanoid metabolism and signaling based on the KEGG pathway database and the literature and have developed a kinetic model. A matrix-based approach was used to estimate the rate constants from experimental data and these were further refined using generalized constrained nonlinear optimization. The resulting model fits the experimental data well for all species, and simulated enzyme activities were similar to their literature values. The quantitative model for eicosanoid metabolism that we have developed can be used to design experimental studies utilizing genetic and pharmacological perturbations to probe fluxes in lipid pathways.     

Methodologic challenges in designing clinical studies to measure differences in the bioequivalence of n-3 fatty acids

Although epidemiologic studies suggest a role for alpha-linolenic acid (ALA) in the prevention of coronary heart disease and certain types of cancer, the findings of clinical studies suggest that ALA is inferior biologically to the n-3 long-chain fatty acids because its bioconversion to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) is limited in humans and because the magnitude of its biologic effects is smaller than that of EPA and DHA. This paper reviews several methodologic issues that may confound the findings of clinical studies and complicate our interpretations of them: the ALA and EPA + DHA dietary enrichment levels; the choice of tissue; the choice of lipid species; and the method of reporting fatty acid composition. Although the ALA enrichment levels used in most clinical studies can be achieved by consuming ground flaxseed, flaxseed oil, canola oil and other ALA-rich plants as part of a typical dietary pattern, the EPA + DHA enrichment levels are not practical and can only be obtained from fish oil supplements. The lack of consistency in the choice of lipids species and the reporting of data makes it difficult to compare outcomes across studies. The choice of tissue (blood) for analysis is a limitation that probably cannot be overcome. The use of practical ALA and EPA+ DHA dietary enrichment levels and some standardization of clinical study design would allow for greater comparisons of outcomes across studies and ensure a more realistic analysis of how individual n-3 fatty acids differ in their biologic effects in humans.     

Immunomodulation by omega-3 fatty acids

The immune system, including its inflammatory components, is fundamental to host defense against pathogenic invaders. It is a complex system involving interactions amongst many different cell types dispersed throughout the body. Central to its actions are phagocytosis, processing of antigens derived from intracellular and extracellular pathogens, activation of T cells with proliferation and production of cytokines that elicit effector cell functions such as antibody production and killing cell activity. Inappropriate immunologic activity, including inflammation, is a characteristic of many common human disorders. Eicosanoids produced from arachidonic acid have roles in inflammation and regulation of T and B lymphocyte functions. Eicosapentaenoic acid (EPA) also gives rise to eicosanoids and docosahexaenoic acid (DHA) to docosanoids; these may have differing properties to arachidonic acid-derived eicosanoids. EPA and DHA give rise to newly discovered resolvins. Human immune cells are typically rich in arachidonic acid, but arachidonic acid, EPA and DHA contents can be altered through oral administration of those fatty acids. This results in a change pattern of production of eicosanoids and probably also of docosanoids and resolvins, although the latter are not well examined in the human context. Changing the fatty acid composition of immune cells also affects phagocytosis, T-cell signaling and antigen presentation capability. These effects appear to mediated at the membrane level suggesting important roles of fatty acids in membrane order, lipid raft structure and function and membrane trafficking.     

Omega-3 fatty acids and metabolic syndrome: Effects and emerging mechanisms of action

Epidemiological, human, animal, and cell culture studies show that n−3 fatty acids, especially α-linolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA), reduce the risk factors of cardiovascular diseases. EPA and DHA, rather than ALA, have been the focus of research on the n−3 fatty acids, probably due to the relatively inefficient conversion of ALA to EPA and DHA in rodents and humans. This review will assess our current understanding of the effects and potential mechanisms of actions of individual n−3 fatty acids on multiple risk factors of metabolic syndrome. Evidence for pharmacological responses and the mechanism of action of each of the n−3 fatty acid trio will be discussed for the major risk factors of metabolic syndrome, especially adiposity, dyslipidemia, insulin resistance and diabetes, hypertension, oxidative stress, and inflammation. Metabolism of n−3 and n−6 fatty acids as well as the interactions of n−3 fatty acids with nutrients, gene expression, and disease states will be addressed to provide a rationale for the use of n−3 fatty acids to reduce the risk factors of metabolic syndrome.     

Exosomes as new vesicular lipid transporters involved in cell–cell communication and various pathophysiologies

Exosomes are nanovesicles that have emerged as a new intercellular communication system between an intracellular compartment of a donor cell towards the periphery or an internal compartment of a recipient cell. The bioactivity of exosomes resides not only in their protein and RNA contents but also in their lipidic molecules. Exosomes display original lipids organized in a bilayer membrane and along with the lipid carriers such as fatty acid binding proteins that they contain, exosomes transport bioactive lipids. Exosomes can vectorize lipids such as eicosanoids, fatty acids, and cholesterol, and their lipid composition can be modified by in-vitro manipulation. They also contain lipid related enzymes so that they can constitute an autonomous unit of production of various bioactive lipids. Exosomes can circulate between proximal or distal cells and their fate can be regulated in part by lipidic molecules. Compared to their parental cells, exosomes are enriched in cholesterol and sphingomyelin and their accumulation in cells might modulate recipient cell homeostasis. Exosome release from cells appears to be a general biological process. They have been reported in all biological fluids from which they can be recovered and can be monitors of specific pathophysiological situations. Thus, the lipid content of circulating exosomes could be useful biomarkers of lipid related diseases. Since the first lipid analysis of exosomes ten years ago detailed knowledge of exosomal lipids has accumulated. The role of lipids in exosome fate and bioactivity and how they constitute an additional lipid transport system are considered in this review.     

Intracellular- and extracellular-derived Ca influence phospholipase A2-mediated fatty acid release from brain phospholipids

Docosahexaenoic acid (DHA) and arachidonic acid (AA) are found in high concentrations in brain cell membranes and are important for brain function and structure. Studies suggest that AA and DHA are hydrolyzed selectively from the sn-2 position of synaptic membrane phospholipids by Ca²⁺-dependent cytosolic phospholipase A₂ (cPLA₂) and Ca²⁺-independent phospholipase A₂ (iPLA₂), respectively, resulting in increased levels of the unesterified fatty acids and lysophospholipids. Cell studies also suggest that AA and DHA release depend on increased concentrations of Ca²⁺, even though iPLA₂ has been thought to be Ca²⁺-independent. The source of Ca²⁺ for activation of cPLA₂ is largely extracellular, whereas Ca²⁺ released from the endoplasmic reticulum can activate iPLA₂ by a number of mechanisms. This review focuses on the role of Ca²⁺ in modulating cPLA₂ and iPLA₂ activities in different conditions. Furthermore, a model is suggested in which neurotransmitters regulate the activity of these enzymes and thus the balanced and localized release of AA and DHA from phospholipid in the brain, depending on the primary source of the Ca²⁺ signal.     

Omega-3 fatty acids in dry eye and corneal nerve regeneration after refractive surgery

Dry eye (DE) is a multifactorial condition that affects the surface of the eye and induces an inflammatory response. Corneal nerves play an important role in the maintenance of a healthy ocular surface. Here we review corneal structure, nerve architecture, DE conditions, and nerve regeneration following corneal surgery and discuss how n-3 fatty acids affect the health of the cornea. Animal studies show that resolvins, compounds derived from eicosapentaenoic acid (EPA), increase tear volume and decrease inflammation induced by DE. After corneal surgery in rabbits, treatment with nerve growth factor (NGF) or pigment epithelial derived factor (PEDF) in conjunction with docosahexaenoic acid (DHA) increase nerve density and corneal epithelial cell proliferation. Increased synthesis of the novel docosanoid, neuroprotectin D1 (NPD1), was found in corneas after the animals were treated with PEDF and DHA. Topical application of these lipids derived from n-3 fatty acids could be useful in treating DE and prevent clinical complications such as cornea erosion and ulcerations.     

Selective regulation of UGT1A1 and SREBP‐1c mRNA expression by docosahexaenoic,eicosapentaenoic, and arachidonic acids

We evaluated, in human cell line HepG2, the action of individual dietary polyunsaturated fatty acids (PUFAs) on the expression of several lipid metabolism genes. The effects of docosahexaenoic acid, 22:6, n‐3 (DHA), eicosapentaenoic acid, 20:5, n‐3 (EPA), and arachidonic acid, 20:4, n‐6 (AA) were studied alone and with vitamin E (Vit.E). DHA, EPA, and AA down‐regulated mRNAs and encoded proteins of stearoyl‐CoA desaturase (SCD) and sterol regulatory element binding protein (SREBP‐1c), two major factors involved in unsaturated fatty acids synthesis. DHA affected SREBP‐1c mRNA less markedly than EPA and AA. Vit.E did not affect these products, both when individually added or together with fatty acids. The expression of UDP‐glucuronosyl transferase 1A1 (UGT1A1) mRNA, an enzyme of phase II drug metabolism with relevant actions within lipid metabolism, resulted also differentially regulated. DHA did not essentially reduce UGT1A1 mRNA expression while EPA and AA produced a considerable decrease. Nevertheless, when these PUFAs were combined with Vit.E, which by itself did not produce any effect, the result was a reduction of UGT1A1 mRNA with DHA, an increase reverting to basal level with EPA and no variation with AA. Observed regulations did not result to be mediated by peroxisome proliferator‐activated receptor (PPAR). Our data indicate that major dietary PUFAs and Vit.E are differentially and selectively able to affect the expression of genes involved in lipid metabolism. The different actions of these slightly different molecules could be associated with their physiological role as relevant nutrient molecules. J. Cell. Physiol. 226: 187–193, 2010. © 2010 Wiley‐Liss, Inc.     

Arachidonic acid and lipoxin A4 as possible endogenous anti-diabetic molecules

In both type 1 and type 2 diabetes mellitus, increased production of pro-inflammatory cytokines and reactive oxygen species (ROS) occurs that induce apoptosis of β cells and cause peripheral insulin resistance respectively though the degree of their increased production is higher in type 1 and less in type 2 diabetes mellitus. Despite this, the exact mechanism(s) that lead to increased production of pro-inflammatory cytokines: interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α) and ROS is not known. Studies showed that plasma concentrations of arachidonic acid (AA) and lipoxin A₄ (LXA₄) are low in alloxan-induced type 1 diabetes mellitus in experimental animals and patients with type 2 diabetes mellitus. Prior administration of AA, eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively) and transgenic animals that produce increased amounts of EPA and DHA acids were protected from chemical-induced diabetes mellitus that was associated with enhanced formation of LXA₄ and resolvins, while protectin D₁ ameliorated peripheral insulin resistance. AA, LXA₄, resolvins and protectins inhibit IL-6 and TNF-α production and suppress ROS generation. Thus, AA and lipoxins, resolvins and protectins may function as endogenous anti-diabetic molecules implying that their administration could be useful in the prevention and management of both types of diabetes mellitus.     

Evaluation of suppressive and pro-resolving effects of EPA and DHA in human primary monocytes and T-helper cells

Despite their beneficial anti-inflammatory properties, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may increase the infection risk at high doses, likely by generating an immune-depressed state. To assess the contribution of different immune cell populations to the immunomodulatory fatty acid effect, we comparatively investigated several aspects of inflammation in human T-helper (Th) cells and monocytes. Both fatty acids, but DHA to a lesser extent compared with EPA, selectively and dose-dependently reduced the percentage of cytokine-expressing Th cells in a peroxisome proliferator-activated receptor (PPAR)γ-dependent fashion, whereas the expression of the cell surface marker CD69 was unaltered on activated T cells. In monocytes, both EPA and DHA increased interleukin (IL)-10 without affecting tumor necrosis factor (TNF)-α and IL-6. Cellular incorporation of EPA and DHA occurred mainly at the expense of arachidonic acid. Concomitantly, thromboxane B (TXB)2 and leukotriene B (LTB)4 in supernatants decreased, while levels of TXB3 and LTB5 increased. This increase was independent of activation and in accordance with cyclooxygenase expression patterns in monocytes. Moreover, EPA and DHA gave rise to a variety of mono- and trihydroxy derivatives of highly anti-inflammatory potential, such as resolvins and their precursors. Our results suggest that EPA and DHA do not generally affect immune cell functions in an inhibitory manner but rather promote pro-resolving responses.     

Lipid and fatty acid composition of muscle and liver from wild and captive mature female broodstocks of white seabream, Diplodus sargus

Total lipids (TL), lipid classes, and their associated fatty acids from muscle and liver of captive and wild mature female broodstocks were investigated in order to estimate the fatty acid requirements of white seabream (Diplodus sargus). The results showed that the percentage of triacylglycerol was higher in liver and muscle of captive fish than in wild fish. The distribution of phospholipid classes in liver and muscle of both fish groups was similar, phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol being the predominant lipid classes. The general pattern of fatty acid distribution in total lipid of liver and muscle from captive and wild fish was similar. However, the relative percentage of specific fatty acids differed in captive and wild fish. The most noteworthy difference was the lower proportion of arachidonic acid (20:4n-6, AA) and the higher proportion of eicosapentaenoic acid (20:5n-3, EPA) in liver and muscle of captive fish with respect to those of wild fish. The proportion of docosahexaenoic acid (22:6n-3, DHA) did not differ between the two fish groups. The differences in EPA and AA proportions between captive and wild fish implied that captive fish presented a higher EPA/AA ratio and a lower DHA/EPA ratio than wild fish. In general terms, in both liver and muscle, the differences in fatty acid composition observed for TL were extended to all lipid classes. The results suggest that the different AA, EPA and DHA proportions in liver and muscle between captive and wild broodstocks are attributed to different levels of these fatty acids in broodstock diets.