Low blood docosahexaenoic acid (DHA) is reported in patients with phenylketonuria (PKU); however, the functional implications in adolescents and adults are unknown. This pilot study investigated the effect of supplemental DHA on cognitive performance in 33 females with PKU ages 12–47 years. Participants were randomly assigned to receive DHA (10 mg/kg/day) or placebo for 4.5 months. Performance on cognitive processing speed and executive functioning tasks was evaluated at baseline and follow up. Intention-to-treat and per protocol analyses were performed. At follow up, biomarkers of DHA status were significantly higher in the DHA-supplemented group. Performance on the cognitive tasks and reported treatment-related adverse events did not differ. While no evidence of cognitive effect was seen, a larger sample size is needed to be conclusive, which may not be feasible in this population. Supplementation was a safe and effective way to increase biomarkers of DHA status (www.clinicaltrials.gov; Identifier: NCT00892554).
Docosahexaenoic acid; Phenylketonuria; Phenylalanine; Cognitive tests; Protein-restricted diet; Clinical trial; Randomized controlled trial
Long chain omega-3 polyunsaturated fatty acids (LC n-3 PUFA) such as EPA and DHA have been shown to possess beneficial health effects, and it is believed that many of their effects are mediated by their oxygenated products (oxylipins). Recently, we have shown that serum levels of several hydroxy, epoxy, and dihydroxy FAs are dependent on the individual status of the parent FAs in a cohort of normo- and hyperlipidemic subjects. So far, the effect of an increased dietary LC n-3 PUFA intake on hydroxy, epoxy, and dihydroxy FA levels has not been investigated in subjects with mild combined hyperlipidemia.
Subjects and Methods
In the present study, we compared oxylipin patterns of 10 hyperlipidemic (cholesterol >200 mg/dl; triglyceride >150 mg/ml) and 10 normolipidemic men in response to twelve weeks of LC n-3 PUFA intake (1.14 g DHA and 1.56 g EPA). Levels of 44 free hydroxy, epoxy and dihydroxy FAs were analyzed in serum by LC-MS. Additionally, oxylipin levels were compared with their parent PUFA levels in erythrocyte membranes; a biomarker for the individual PUFA status.
Differences in the oxylipin pattern between normo- and hyperlipidemic subjects were minor before and after treatment. In all subjects, levels of EPA-derived oxylipins (170–4,800 pM) were considerably elevated after LC n-3 PUFA intake (150–1,400 %), the increase of DHA-derived oxylipins (360–3,900 pM) was less pronounced (30–130 %). The relative change of EPA in erythrocyte membranes is strongly correlated (r ≥ 0.5; p<0.05) with the relative change of corresponding epoxy and dihydroxy FA serum levels. The effect on arachidonic acid (AA)-derived oxylipin levels (140–27,100 pM) was inconsistent.
Discussion and Conclusions
The dietary LC PUFA composition has a direct influence on the endogenous oxylipin profile, including several highly biological active EPA- and DHA-derived lipid mediators. The shift in oxylipin pattern appears to be dependent on the initial LC PUFA status particularly for EPA. The finding that also levels of other oxylipins derived from ALA, LA or AA are modified by LC n-3 PUFA intake might suggest that at least some of the effects of EPA and DHA could be mediated by a shift in the entire oxylipin profile.
eicosanoids; epoxides; diols; EPA; DHA; PUFA; arachidonic acid; hyperlipidemia; omega-3 fatty acids
The effects of an oral fish oil treatment regimen on sensorimotor, blood-brain barrier, and biochemical outcomes of traumatic brain injury (TBI) were investigated in a juvenile rat model. Seventeen-day old Long-Evans rats were given a 15 mL/kg fish oil (2.01 g/kg EPA, 1.34 g/kg DHA) or soybean oil dose via oral gavage 30 minutes prior to being subjected to a controlled cortical impact injury or sham surgery, followed by daily doses for seven days. Fish oil treatment resulted in less severe hindlimb deficits after TBI as assessed with the beam walk test, decreased cerebral IgG infiltration, and decreased TBI-induced expression of the Mmp9h gene one day after injury. These results indicate that fish oil improved functional outcome after TBI resulting, at least in part from decreased disruption of the blood-brain barrier through a mechanism that includes attenuation of TBI-induced expression of Mmp9.
traumatic brain injury; juvenile; rat; fish oil; blood-brain barrier; matrix metalloproteinase 9
Recommendations to consume fish for cardiovascular disease (CVD) prevention and its generally recognized as safe (GRAS) status have had the unanticipated consequence of encouraging long-chain omega-3 (ω-3) fatty acid [(eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] supplementation and fortification practices. While there is evidence supporting a protective role for EPA/DHA supplementation for reducing sudden cardiac events, the safety and efficacy of supplementation with LCω-3PUFA in the context of other disease outcomes is unclear. Recent studies of bacterial, viral, and fungal infections in animal models of infectious disease demonstrate that LCω-3PUFA intake dampens immunity and alters pathogen clearance and result in reduced survival. The same physiological properties of EPA/DHA that are responsible for the amelioration of inflammation associated with chronic cardiovascular pathology or autoimmune states, may impair pathogen clearance during acute infections by decreasing host resistance or interfere with tumor surveillance resulting in adverse health outcomes. Recent observations that high serum LCω-3PUFA levels are associated with higher risk of prostate cancer and atrial fibrillation have heightened the concern for adverse outcomes. Given the widespread use of supplements and fortification of common food items with LCω-3PUFA, this review focuses on the immunomodulatory effects of the dietary LCω-3PUFAs, EPA and DHA, the mechanistic basis for potential negative health outcomes, and calls for biomarker development and validation as rational first steps for setting recommended dietary intake levels.
Fenton, JI; Hord, NG; Ghosh, S; Gurzell, EA
Molecular regulation of fatty acid desaturase (Fads) gene expression by dietary arachidonic (ARA) and docosahexaenoic acid (DHA) during early postnatal period, when the demand for long chain polyunsaturated fatty acids (LC-PUFA) is very high, has not been well defined. The objective of the current study was to determine regulation of liver Fads1, Fads2 and Fads3 classical (CS) and alternative transcripts (AT) expression by dietary ARA and DHA, within the physiological range present in human breast milk, in suckling piglets. Piglets were fed one of six milk replacer formula diets (Formula-reared groups, FR) with varying ARA and DHA content from days 3-28 of age. The ARA/DHA levels of the six formula diets were as follows (% total fatty acid, FA/FA): (A1) 0.1/1.0; (A2) 0.53/1.0; (A3-D3) 0.69/1.0; (A4) 1.1/1.0; (D2) 0.67/0.62; (D1) 0.66/0.33. The control maternal-reared (MR) group remained with the dam. Fads1 expression was not significantly different between FR and MR groups. Fads2 expression was down-regulated significantly in diets with 1:1 ratio of ARA:DHA, compared to MR. Fads2 AT1 expression was highly correlated to Fads2 expression. Fads3 AT7 was the only Fads3 transcript sensitive to dietary LC-PUFA intake and was up-regulated in the formula diets with lowest ARA and DHA content compared to MR. Thus, the present study provides evidence that the proportion of dietary ARA:DHA is a significant determinant of Fads2 expression and LC-PUFA metabolism during the early post-natal period. Further, the data suggest that Fads3 AT7 may have functional significance when dietary supply of ARA and DHA are low during early development.
Arachidonic acid; Docosahexaenoic acid; fatty acid desaturase gene; infant nutrition; piglet
Previously, we, and others, have demonstrated a rapid and significant post-mortem increase in brain prostanoid (PG) levels analyzed without microwave fixation, and this is not the result of PG trapping or destruction in microwave-irradiated brain tissue. In the present study, we demonstrate a dramatic increase in kidney eicosanoid levels when analyzed without microwave fixation which was mainly accounted for by the 142-, 81-, and 62-fold increase in medullary 6-ketoPGF1α, PGE2, and PGF2α, levels, respectively, while PGD2 and TXB2 levels were increased ~7-fold. Whole kidney and cortex PG were also significantly increased in nonmicrowaved tissue, but at lesser extent. Arachidonic acid and the lipoxygenase products hydroxyeicosatetraenoic acids (HETE) were also induced in whole kidney, cortex, and medulla 1.5- to 5.5- fold depending upon tissue and metabolite. Cyclooxygenase inhibition with indomethacin decreased PG mass in non-microwaved tissue to basal levels, however HETE and arachidonic acid were not decreased. These data demonstrate the critical importance of kidney tissue fixation to limiting artifacts during kidney eicosanoid analysis.
Prostanoids and PGE2 in particular have been long viewed as one of the major mediators of inflammation in arthritis. However, experimental data indicate that PGE2 can serve both pro- and anti-inflammatory functions. We have previously shown (Kojima, F. et al. 2008 J. Immunol. 180, 8361-8368) that microsomal prostaglandin E synthase-1 (mPGES-1) deletion, which regulates PGE2 production, resulted in the suppression of collagen-induced arthritis (CIA) in mice. This suppression was attributable, at least in part, to the impaired generation of type II collagen autoantibodies. In order to examine the function of mPGES-1 and PGE2 in a non-autoimmune form of arthritis, we used the collagen antibody-induced arthritis (CAIA) model in mice deficient in mPGES-1, thereby bypassing the engagement of the adaptive immune response in arthritis development. Here we report that mPGES-1 deletion significantly increased CAIA disease severity. The latter was associated with a significant (~3.6) upregulation of neutrophil, but not macrophage, recruitment to the inflamed joints. The lipidomic analysis of the arthritic mouse paws by quantitative liquid chromatography / tandem mass-spectrometry (LC/MS/MS) revealed a dramatic (~59-fold) reduction of PGE2 at the peak of arthritis. Altogether, this study highlights mPGES-1 and its product PGE2 as important negative regulators of neutrophil-mediated inflammation and suggests that specific mPGES-1 inhibitors may have differential effects on different types of inflammation. Furthermore, neutrophil-mediated diseases could be exacerbated by inhibition of mPGES-1.
Nanohybrids; Room-temperature phosphorescence(RTP); Sensor; Rutin
Prevention of ovarian cancer is the best approach for reducing the impact of this deadly disease. The laying hen is a robust model of spontaneous ovarian cancer that recapitulates the human disease. Dietary intervention with flaxseed, the richest vegetable source of omega-3 fatty acids (OM-3FAs) and phytoestrogen lignans, demonstrate the potential for effective prevention and amelioration of ovarian cancer by targeting inflammatory prostaglandin pathways. Prostaglandin E2 (PGE2) is the most pro-inflammatory ecoisanoid and one of the downstream products of two isoforms of cyclooxygenase (COX) enzymes: COX-1 and COX-2. Our objective was to investigate the effect of flaxseed supplementation for one year on ovarian cancer and correlate its effects to expression of COX enzymes and concentrations of prostaglandins. White Leghorn hens were fed 10% flaxseed-enriched or standard diet for one year. The severity of ovarian cancer was determined by gross pathology and histology. COX-1 and COX-2 localization and protein and mRNA expression and PGE2 and PGE3 concentrations in ovaries were measured by IHC, western blot, quantitative real-time PCR and LC-MS-MS, respectively. The results demonstrated a significant reduction in late stage ovarian tumors in the flaxseed-fed hens compared with the control diet-fed hens. In correlation with decreased ovarian cancer severity, concentrations of PGE2 and expression of COX-2 were diminished in ovaries of flaxseed-fed hens. PGE3 concentrations were below the level of detection. The results demonstrated that in normal ovaries, COX-1 was localized to the granulosa cell layer surrounding the follicles and ovarian surface epithelium (OSE) whereas COX-2 protein was localized to the granulosa cell layer in the follicle. Extensive COX-1 and COX-2 protein expression was found throughout the ovarian carcinoma. Our findings suggest that the flaxseed-mediated reduction in the severity of ovarian cancer in hens is correlated to the reduction in PGE2 in the ovaries of flaxseed-fed hens. These findings may provide the basis for clinical trials of dietary intervention targeting prostaglandin biosynthesis for the prevention and treatment of ovarian cancer.
Flaxseed; Cyclooxygenases; Prostaglandin E2; Ovarian cancer; Laying hen
The effects of dietary modulation of brain DHA content on outcomes after TBI were examined in a juvenile rat model. Long-Evans rats with normal or diet-induced decreases in brain DHA were subjected to a controlled cortical impact or sham surgery on postnatal day 17. Rats with the greatest decreases in brain DHA had the poorest sensorimotor outcomes after TBI. Ccl2, Gfap, and Mmp 9 mRNA levels, and MMP-2 and −9 enzymatic activities were increased after TBI regardless of brain DHA level. Lesion volume was not affected by brain DHA level. In contrast, TBI-induced Timp1 expression was lower in rats on the Deficient diet and correlated with brain DHA level. These data suggest that decreased brain DHA content contributes to poorer sensorimotor outcomes after TBI through a mechanism involving modulation of Timp1 expression.
Echium oil (EO) contains stearidonic acid (18:4), a n-3 polyunsaturated fatty acids (PUFAs), and gamma-linolenic acids (18:3), a n-6 PUFA that can be converted to long chain (LC)-PUFAs. We aimed to compare a safflower oil (SO)-enriched diet to EO- and fish oil (FO)-enriched diets on circulating and tissue PUFAs levels and glycemic, inflammatory, and cardiovascular health biomarkers in insulin resistant African green monkeys. In a Latin-square cross-over study, eight monkeys consumed matched diets for 6 weeks with 3-week washout periods. Monkeys consuming FO had significantly higher levels of n-3 LC-PUFAs and EO supplementation resulted in higher levels of circulating n-3 LC-PUFAs and a significant increase in dihomo-gamma linolenic acid (DGLA) in red blood cells and muscle. Glucose disposal was improved after EO consumption. These data suggest that PUFAs in EO supplementation have the capacity to alter circulating, RBC and muscle LC-PUFA levels and improve glucose tolerance in insulin-resistant monkeys.
Echium oil; Fish oil; Stearidonic acid; Polyunsaturated fatty acids; Gamma-Linolenic acid; Diabetes
Many diabetics are insensitive to aspirin’s platelet anti-aggregation effects. The possible modulating effects of coadministration of aspirin and fish oil in subjects with diabetes are poorly characterized.
Participants and Methods
Thirty adults with type 2 diabetes mellitus were treated with aspirin 81 mg/d for 7 days, then with fish oil 4g/day for 28 days, then the combination of fish oil and aspirin for another 7 days.
Aspirin alone and in combination with fish oil reduced platelet aggregation in most participants. Five of 7 participants classified as aspirin insensitive 1 week after daily aspirin ingestion were sensitive after the combination. Although some platelet aggregation measures correlated positively after aspirin and fish oil ingestion alone and (in combination) in all individuals, correlation was only observed in those who were aspirin insensitive after ingestion of the combination.
Co-adminstration of aspirin and fish oil may reduce platelet aggregation more than aspirin alone in adults with diabetes mellitus.
Omega-3 fatty acids; eicosapentaenoic acid; docosahexaenoic acid; aspirin; acetylsalicylic acid; platelet function; NF-kappaB; nuclear factor kappa-light-chain-enhancer of activated B cells
Oxylipins, the oxidation products of unsaturated fatty acids (FA), are potent endogenous mediators being involved in regulation of various biological processes such as inflammation, pain and blood coagulation. Compared to oxylipins derived from arachidonic acid (AA) by cyclooxygenase action, i.e. prostanoides, only limited information is available about the endogenous levels of hydroxy-, epoxy- and dihydroxy-FA of linoleic acid (LA), AA, α-linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in humans. Particularly, it is unknown how metabolic disorders affect endogenous oxylipin levels in humans. Therefore, in the present study we compared the serum concentrations of 44 oxylipins in 20 normolipidemic with 20 hyperlipidemic (total cholesterol > 200 mg/dl; LDL-C > 130 mg/dl; TG > 150 mg/ml) men (age 29–51 y). The serum concentration varied strongly among subjects. For most hydroxy-, epoxy- and dihydroxy-FA the concentration were comparable to those of plasma reported in earlier studies. Despite the significant change in blood lipid levels the hyperlipidemic group showed only minor differences in oxylipin levels. The hyperlipidemic subjects had a slightly higher serum concentration of 8,9-DiHETrE, 5-HEPE, 10,11-DiHDPE, and a lower concentration of 12,13-DiHOME, 12-HETE, 9,10-DiHODE, and 12,13-DiHODE compared to normolipidemic subjects. Overall the hydroxy-, epoxy- and dihydroxy-FA levels were not changed suggesting that mild combined hyperlipidemia has no apparent effect on the concentration of circulating oxylipins. By contrast, serum levels of several hydroxy-, epoxy-, and dihydroxy-FA are dependent on the individual status of the parent FA. Particularly, a strong correlation between the EPA content in the erythrocyte membrane and the serum concentration of EPA derived oxylipins was observed. Given that the synthesis of EPA from other n3-FA in humans is low, this suggests that oxylipin levels can be directly influenced by the diet.
Eicosanoids; PUFA; Arachidonic acid; eicosapentaenoic acid; hyperlipidemia; omega-3 fatty acids
More than a dozen epidemiological studies have reported that reduced levels or intake of omega-3 fatty acids or fish consumption is associated with increased risk for age-related cognitive decline or dementia such as Alzheimer's disease (AD). Increased dietary consumption or blood levels of docosahexaenoic acid (DHA) appear protective for AD and other dementia in multiple epidemiological studies; however, three studies suggest that the ApoE4 genotype limits protection. DHA is broadly neuroprotective via multiple mechanisms that include neuroprotective DHA metabolites, reduced arachidonic acid metabolites, and increased trophic factors or downstream trophic signal transduction. DHA is also protective against several risk factors for dementia including head trauma, diabetes, and cardiovascular disease. DHA is specifically protective against AD via additional mechanisms: It limits the production and accumulation of the amyloid β peptide toxin that is widely believed to drive the disease; and it also suppresses several signal transduction pathways induced by Aβ, including two major kinases that phosphorylate the microtubule associated protein tau and promote neurofibrillary tangle pathology. Based on the epidemiological and basic research data, expert panels have recommended the need for clinical trials with omega-3 fatty acids, notably DHA, for the prevention or treatment of age-related cognitive decline—with a focus on the most prevalent cause, AD. Clinical trials are underway to prevent and treat AD. Results to-date suggest that DHA may be more effective if it is begun early or used in conjunction with antioxidants.
Alzheimer's disease; dementia; omega-3 fatty acid (n-3); docsahexaenoic acid (DHA); amyloid
DHA (22:6n-3) supplementation during infancy has been associated with lower heart rate (HR) and improved neurobehavioral outcomes. We hypothesized that maternal DHA supplementation would improve fetal cardiac autonomic control and newborn neurobehavior. Pregnant women were randomized to 600 mg/day of DHA or placebo oil capsules at 14.4 (+/−4) weeks gestation. Fetal HRand HRV were calculated from magnetocardiograms (MCGs) at 24, 32 and 36 weeks gestational age (GA). Newborn neurobehavior was assessed using the Neonatal Behavioral Assessment Scale (NBAS). Postpartum maternal and infant red blood cell (RBC) DHA was significantly higher in the supplemented group as were metrics of fetal HRV and newborn neurobehavior in the autonomic and motor clusters. Higher HRV is associated with more responsive and flexible autonomic nervous system (ANS). Coupled with findings of improved autonomic and motor behavior, these data suggest that maternal DHA supplementation during pregnancy may impart an adaptive advantage to the fetus.
Docosahexaenoic acid; Autonomic nervous system; Fetal; Magnetocardiology; Heart rate variability
Cyclooxygenase (COX) inhibiting drugs augment muscle mass and strength improvements during resistance exercise based treatment of sarcopenia in older individuals. Initial evidence suggests a potential mechanism of COX inhibitor blunted prostaglandin (PG) E2 stimulation of interleukin (IL)-6 and the ubiquitin ligase MuRF-1, reducing their inhibition on muscle growth. The purpose of this investigation was to determine if PGE2 stimulates IL-6 and MuRF-1 transcription in skeletal muscle. Muscle biopsies were obtained from 10 young individuals and incubated ex vivo with PGE2 or control and analyzed for IL-6 and MuRF-1 mRNA levels. PGE2 upregulated (P<0.05) expression of both IL-6 (195%) and MuRF-1 (51%). A significant relationship was found between IL-6 and MuRF-1 expression after incubation with PGE2 (r=0.77, P<0.05), suggesting regulation through a common pathway. PGE2 induces IL-6 and MuRF-1 transcription in human skeletal muscle, providing a mechanistic link between COX inhibiting drugs, PGE2, and the regulation of muscle mass.
PGE2; Skeletal muscle; IL-6; MuRF-1
The composition of the lipid matrix is critical for function of membrane proteins. Perhaps one of the best studied examples is the function of the G-protein-coupled membrane receptor (GPCR) rhodopsin which is located in membranes with high content of phospholipids with polyunsaturated docosahexaenoic acid chains (DHA, 22:6n-3). Technological advances enabled a more detailed study of structure and dynamics of DHA chains and their interaction with rhodopsin. It was established that polyunsaturated DHA differs from saturated and monounsaturated hydrocarbon chains by far more rapid structural conversions. Furthermore, DHA chains tend to have higher density near the lipid/water interface while density of saturated chains is higher in the bilayer center. The interface of rhodopsin has a small number of sites for tighter interaction with DHA. Polyunsaturated phosphatidylethanolamines accumulate preferentially near the protein. Surprisingly, the high conformational freedom of most DHA chains is not measurably reduced upon interaction with rhodopsin. While some observations point at an involvement of continuum elastic properties of membranes in modulation of rhodopsin function, there is growing evidence for a role of weakly specific DHA-rhodopsin interactions.
Docosahexaenoic Acid; G-Protein-coupled membrane receptor; Rhodopsin; Nuclear Magnetic Resonance; Neutron Scattering
The hippocampal CA1 region is most susceptible to cerebral ischemia in both rodents and humans, whereas CA3 is remarkably resistant. Here, we investigated the possible role of membrane lipids in differential susceptibility in these regions. Transient ischemia was induced in rats via bilateral occlusion of common carotid arteries and membrane lipids were analyzed by mass spectrometry. While lipid profile differences between the intact CA1 and CA3 were rather minor, ischemia caused significant pyramidal cell death with concomittant reduction of phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, plasmalogen and sphingomyelin only in CA1. The phospholipid loss was evenly distributed in most molecular species. Ischemia also significantly increased cell death mediator ceramides only in CA1. Our data suggests that differential susceptibility to ischemia between CA1 and CA3 is not linked to their unique phospholipid profile. Also, selective activation of phospholipase A2, which primarily releases polyunsaturated fatty acids, might not be characteristic to cell death in CA1.
polyunsaturated fatty acids; ischemia; hippocampus; phospholipids
Maternal n-3 and n-6 polyunsaturated fatty acid (PUFA) status may influence birth outcomes and child health. We assessed second trimester maternal diet with food frequency questionnaires (FFQs) (n = 1666), mid-pregnancy maternal erythrocyte PUFA concentrations (n = 1550), and umbilical cord plasma PUFA concentrations (n = 449). Mean (SD) maternal intake of total n-3 PUFA was 1.17 g/d (0.43), docosahexaenoic and eicosapentaenoic acids (DHA+EPA) 0.16 g/d (0.17), and total n-6 PUFA 12.25 g/d (3.25). Mean maternal erythrocyte and cord plasma PUFA concentrations were 7.0% and 5.2% (total n-3), 5.0% and 4.6% (DHA+EPA), and 27.9% and 31.4% (total n-6). Mid-pregnancy diet–blood and blood–blood correlations were strongest for DHA+EPA (r = 0.38 for diet with maternal blood, r = 0.34 for diet with cord blood, r = 0.36 for maternal blood with cord blood), and less strong for n-6 PUFA. The FFQ is a reliable measure of elongated PUFA intake, although inter-individual variation is present
Pregnancy; Diet; n-3 fatty acids; n-6 fatty acids
The fatty acid desaturase (FADS) gene family at 11q12-13.1 includes FADS1 and FADS2, both known to mediate biosynthesis of omega-3 and omega-6 long-chain polyunsaturated fatty acids (LCPUFA). FADS3 is a putative desaturase due to its sequence similarity with FADS1 and FADS2, but its function is unknown. We have previously described 7 FADS3 alternative transcripts (AT) and 1 FADS2 AT conserved across multiple species. This study examined the effect of dietary LCPUFA levels on liver FADS gene expression in vivo and in vitro, evaluated by qRT-PCR. Fourteen baboon neonates were randomized to three diet groups for their first 12 weeks of life: C: Control, no LCPUFA; L: 0.33% docosahexaenoic acid (DHA)/ 0.67% arachidonic acid (ARA) (w/w); and L3: 1.00% DHA/ 0.67% ARA (w/w). Liver FADS1 and both FADS2 transcripts were downregulated by at least 50% in the L3 group compared to controls. In contrast, FADS3 AT were upregulated (L3>C), with four transcripts significantly upregulated by 40% or more. However, there was no evidence for a shift in liver fatty acids to coincide with increased FADS3 expression. Significant upregulation of FADS3 AT was also observed in human liver-derived HepG2 cells after DHA or ARA treatment. The PPARγ antagonist GW9662 prevented FADS3 upregulation, while downregulation of FADS1 and FADS2 was unaffected. Thus, FADS3 AT were directly upregulated by LCPUFA by a PPARγ-dependent mechanism unrelated to regulation of other desaturases. This opposing pattern and mechanism of regulation suggests a dissimilar function for FADS3 AT compared to other FADS gene products.
docosahexaenoic acid; arachidonic acid; polyunsaturated fatty acids; fatty acid desaturase; FADS3; alternative splicing
Bioactive n-3 polyunsaturated fatty acids (PUFA), abundant in fish oil, have potential for treating symptoms associated with inflammatory and metabolic disorders; therefore, it is essential to determine their fundamental molecular mechanisms. Recently, several labs have demonstrated the n-3 PUFA docosahexaenoic acid (DHA) exerts anti-inflammatory effects by targeting the molecular organization of plasma membrane microdomains. Here we briefly review the evidence that DHA reorganizes the spatial distribution of microdomains in several model systems. We then emphasize how models on DHA and plasma membrane microdomains can be applied to mitochondrial membranes. We discuss the role of DHA acyl chains in regulating mitochondrial lipid-protein clustering, and how these changes alter several aspects of mitochondrial function. In particular, we summarize effects of DHA on mitochondrial respiration, electron leak, permeability transition, and mitochondrial calcium handling. Finally, we conclude by postulating future experiments that will augment our understanding of DHA-dependent membrane organization in health and disease.
Fish oil, enriched in bioactive n-3 polyunsaturated fatty acids (PUFA), has been shown to play a role in prevention of colon cancer. The effects of n-3 PUFA are pleiotropic and multifaceted, resulting in an incomplete understanding of their molecular mechanisms of action. Here, we focus on a highly conserved mechanism of n-3 PUFA, which is the alteration of the organization of the plasma membrane. We highlight recent work demonstrating that enrichment of n-3 PUFA in the plasma membrane alters the lateral organization of membrane signaling assemblies (i.e. lipid rafts). This mechanism is central for n-3 PUFA regulation of downstream signaling, T-cell activation, transcriptional activation, and cytokine secretion. We conclude that these studies provide strong evidence for a predominant mechanism by which n-3 PUFA function in colon cancer prevention.
n-3 polyunsaturated fatty acids; DHA; EPA; lipid rafts; colon cancer; chemoprevention; T-lymphocytes