An extraordinary degree of structural specificity is required in neural phospholipids for optimal brain function: n-6 docosapentaenoic acid substitution for docosahexaenoic acid leads to a loss in spatial task performance

Dietary fatty acids and flight-training influence the expression of the eicosanoid hormone prostacyclin in songbirds

Diet shifts can alter tissue fatty acid composition in birds, which is subsequently related to metabolic patterns. Eicosanoids, short-lived fatty acid-derived hormones, have been proposed to mediate these relationships but neither baseline concentrations nor the responses to diet and exercise have been measured in songbirds. We quantified a stable derivative of the vasodilatory eicosanoid prostacyclin in the plasma of male European Starlings (Sturnus vulgaris, N = 25) fed semisynthetic diets with either high (PUFA) or low (MUFA) amounts of n6 fatty acid precursors to prostacyclin. Plasma samples were taken from each bird before, immediately after, and two days following a 15-day flight-training regimen that a subset of birds (N = 17) underwent. We found elevated prostacyclin levels in flight-trained birds fed the PUFA diet compared to those fed the MUFA diet and a positive relationship between prostacyclin and body condition, indexed by fat score. Prostacyclin concentrations also significantly decreased at the final time point. These results are consistent with the proposed influences of precursor availability (i.e., dietary fatty acids) and regulatory feedback associated with exercise (i.e., fuel supply and inflammation), and suggest that prostacyclin may be an important mediator of dietary influence on songbird physiology.

Investigating the catalytic efficiency of C22-Fatty acids with LOX human isozymes and the platelet response of the C22-oxylipin products

Polyunsaturated fatty acids (PUFAs) have been extensively studied for their health benefits because they can be oxidized by lipoxygenases to form bioactive oxylipins. In this study, we investigated the impact of double bond placement on the kinetic properties and product profiles of human platelet 12-lipoxygenase (h12-LOX), human reticulocyte 15-lipoxygenase-1 (h15-LOX-1), and human endothelial 15-lipoxygenase-2 (h15-LOX-2) by using 22-carbon (C22) fatty acid substrates with differing double bond content. With respect to kcat/KM values, the loss of Δ4 and Δ19 led to an 18-fold loss of kinetic activity for h12-LOX, no change in kinetic capability for h15-LOX-1, but a 24-fold loss for h15-LOX-2 for both C22-FAs. With respect to the product profiles, h12-LOX produced mainly 14-oxylipins. For h15-LOX-1, the 14-oxylipin production increased with the loss of either Δ4 and Δ19, however, the 17-oxylipin became the major species upon loss of both Δ4 and Δ19. h15-LOX-2 produced mostly the 17-oxylipin products throughout the fatty acid series. This study also investigated the effects of various 17-oxylipins on platelet activation. The results revealed that both 17(S)-hydroxy-4Z,7Z,10Z,13Z,15E,19Z-DHA (17-HDHA) and 17-hydroxy-4Z,7Z,10Z,13Z,15E-DPAn6 (17-HDPAn6) demonstrated anti-aggregation properties with thrombin or collagen stimulation. 17-hydroxy-7Z,10Z,13Z,15E,19Z-DPAn3 (17-HDPAn3) exhibited agonistic properties, and 17-hydroxy-7Z,10Z,13Z,15E-DTA (17-HDTA) showed biphasic effects, inhibiting collagen-induced aggregation at lower concentrationsbut promoting aggregation at higher concentrations. Both 17-hydroxy-13Z,15E,19Z-DTrA (17-HDTrA), and 17-hydroxy-13Z,15E-DDiA (17-HDDiA) induced platelet aggregation. In summary, the number and placement of the double bonds affect platelet activation, with the general trend being that more double bonds generally inhibit aggregation, while less double bonds promote aggregation. These findings provide insights into the potential role of specific fatty acids and their metabolizing LOX isozymes with respect to cardiovascular health.

7,10,13,16-Docosatetraenoic acid impairs neurobehavioral development by increasing reactive oxidative species production in Caenorhabditis elegans

AIMS

To investigate human breast milk (HBM) lipids that may adversely affect infant neurodevelopment.

MAIN METHODS

We performed multivariate analyses that combined lipidomics and psychologic Bayley-III scales to identify which HBM lipids are involved in regulating infant neurodevelopment. We observed a significant moderate negative correlation between 7,10,13,16-docosatetraenoic acid (omega-6, C₂₂H₃₆O₂, the common name adrenic acid, AdA) and adaptive behavioral development. We further studied the effects of AdA on neurodevelopment by using Caenorhabditis elegans (C. elegans) as a model. Worms from larval stages L1 to L4 were supplemented with AdA at 5 nominal concentrations (0 μM [control], 0.1 μM, 1 μM, 10 μM, and 100 μM) and subjected to behavioral and mechanistic analyses.

KEY FINDINGS

Supplementation with AdA from larval stages L1 to L4 impaired neurobehavioral development, such as locomotive behaviors, foraging ability, chemotaxis behavior, and aggregation behavior. Furthermore, AdA upregulated the production of intracellular reactive oxygen species. AdA-induced oxidative stress blocked serotonin synthesis and serotoninergic neuron activity and inhibited expression of daf-16 and the daf-16-regulated genes mtl-1, mtl-2, sod-1, and sod-3, resulting in attenuation of the lifespan in C. elegans.

SIGNIFICANCE

Our study reveals that AdA is a harmful HBM lipid that may have adverse effects on infant adaptive behavioral development. We believe this information may be critical for AdA administration guidance in children's health care.

Sex differences in hippocampal-dependent memory and the hippocampal lipidome in adolescent rats raised on diets with or without DHA

Recent studies suggest the effects of DHA supplementation on human memory may differ between females and males during infancy, adolescence, and early adulthood, but the underlying mechanisms are not clear. As a result, this study sought to examine the spatial memory and brain lipidomic profiles in female and male adolescent rats with or without a DHA-enriched diet that began perinatally with the supplementation of dams. Spatial learning and memory were examined in adolescent rats using the Morris Water Maze beginning at 6 weeks of age and animals were sacrificed at 7 weeks of age to permit isolation of brain tissue and blood samples. Behavioral testing showed that there was a significant diet x sex interaction for two key measures of spatial memory (distance to zone and time spent in the correct quadrant during the probe test), with female rats benefiting the most from DHA supplementation. Lipidomic analyses suggest levels of arachidonic acid (ARA) and n-6 docosapentaenoic acid (DPA) containing phospholipid species were lower in the hippocampus of DHA supplemented compared with control animals, and principal component analyses revealed a potential dietary treatment effect for hippocampal PUFA. Females fed DHA had slightly more PE P-18:0_22:6 and maintained levels of PE 18:0_20:4 in the hippocampus in contrast with males fed DHA. Understanding how DHA supplementation during the perinatal and adolescent periods changes cognitive function in a sex-specific manner has important implications for determining the dietary requirements of DHA. This study adds to previous work highlighting the importance of DHA for spatial memory and provides evidence that further research needs to consider how DHA supplementation can cause sex-specific changes.

Toward assessing the role of dietary fatty acids in lamb's neurological and cognitive development

Understanding and measuring sheep cognition and behavior can provide us with measures to safeguard the welfare of these animals in production systems. Optimal neurological and cognitive development of lambs is important to equip individuals with the ability to better cope with environmental stressors. However, this development can be affected by nutrition with a special role from long-chain fatty acid supply from the dam to the fetus or in lamb's early life. Neurological development in lambs takes place primarily during the first two trimesters of gestation. Through late fetal and early postnatal life, the lamb brain has a high level of cholesterol synthesis. This rate declines rapidly at weaning and remains low throughout adulthood. The main polyunsaturated fatty acids (PUFA) in the brain are ω-6 arachidonic acid and ω-3 docosahexaenoic acid (DHA), which are elements of plasma membranes' phospholipids in neuronal cells. DHA is essential for keeping membrane integrity and is vital for normal development of the central nervous system (CNS), and its insufficiency can damage cerebral functions and the development of cognitive capacities. In sheep, there is evidence that supplying PUFA during gestation or after birth may be beneficial to lamb productive performance and expression of species-specific behaviors. The objective of this perspective is to discuss concepts of ruminant behavior and nutrition and reflect on future research directions that could help to improve our knowledge on how dietary fatty acids (FA) relate to optimal neurological and cognitive development in sheep.

Systemic Elevation of n-3 Polyunsaturated Fatty Acids (n-3-PUFA) Is Associated with Protection against Visual, Motor, and Emotional Deficits in Mice following Closed-Head Mild Traumatic Brain Injury

Traumatic brain injury (TBI) causes neuroinflammation and neurodegeneration leading to various pathological complications such as motor and sensory (visual) deficits, cognitive impairment, and depression. N-3 polyunsaturated fatty acid (n-3 PUFA) containing lipids are known to be anti-inflammatory, whereas the sphingolipid, ceramide (Cer), is an inducer of neuroinflammation and degeneration. Using Fat1⁺-transgenic mice that contain elevated levels of systemic n-3 PUFA, we tested whether they are resistant to mild TBI-mediated sensory-motor and emotional deficits by subjecting Fat1-transgenic mice and their WT littermates to focal cranial air blast (50 psi) or sham blast (0 psi, control). We observed that visual function in WT mice was reduced significantly following TBI but not in Fat1⁺-blast animals. We also found Fat1⁺-blast mice were resistant to the decline in motor functions, depression, and fear-producing effects of blast, as well as the reduction in the area of oculomotor nucleus and increase in activated microglia in the optic tract in brain sections seen following blast in WT mice. Lipid and gene expression analyses confirmed an elevated level of the n-3 PUFA eicosapentaenoic acid (EPA) in the plasma and brain, blocking of TBI-mediated increase of Cer in the brain, and decrease in TBI-mediated induction of Cer biosynthetic and inflammatory gene expression in the brain of the Fat1⁺ mice. Our results demonstrate that suppression of ceramide biosynthesis and inflammatory factors in Fat1⁺-transgenic mice is associated with significant protection against the visual, motor, and emotional deficits caused by mild TBI. This study suggests that n-3 PUFA (especially, EPA) has a promising therapeutic role in preventing neurodegeneration after TBI.

Evidence of multiple hepatic mechanisms to mobilize docosahexaenoic acid into dam plasma during pregnancy in chow-fed sprague dawley rats

Fetal brain growth requires considerable amounts of docosahexaenoic acid (DHA) during late pregnancy that is associated with increased maternal/dam plasma levels of PC 16:0_22:6 (palmitoyl docosahexaenoyl phosphatidylcholine). While biosynthesis of DHA during pregnancy is upregulated, the mechanisms responsible for the incorporation of dam DHA into PC 16:0_22:6 are not understood. The present study used a discovery approach combining untargeted lipidomics of plasma and liver (n = 3/group) with semi-targeted qPCR of hepatic gene products (n = 6/group) to identify metabolic pathways related to DHA metabolism, with a hypothesis that an upregulated acyltransferase involved in PC remodeling would be identified. Sprague Dawley rats were fed a commercial rodent chow throughout the study and samples were collected before pregnancy (baseline), at 15 and 20 days of pregnancy, and 7 days postpartum. Plasma and hepatic PC 16:0_22:6 was significantly increased (by 79% and 194%, respectively) at day 20 of pregnancy. An increase in hepatic DG (diacylglycerol) 16:0_22:6 (by 243%) and significant decreases in Pla2G15 (0.4-fold) and Pla2G16 (0.6-fold) at day 20 of pregnancy, no changes in Lpcat1-4, and an abundant pool of hepatic pool PE (phosphatidylethanolamine) 16:0_22:6 suggest that plasma PC 16:0_22:6 is not being produced by fatty acyl remodeling during pregnancy. The increase in plasma PC 16:0_22:6 during pregnancy appears to be due to an increase in de novo synthesis of PC and both the CDP-choline and phosphatidylcholine methyltransferase pathways are implicated. There was also evidence suggesting channeling of DHA into PC and lipoprotein assembly may be occurring. Targeted research is necessary to confirm these findings, but the results of this study indicate metabolic adaptions to enable maternal/dam resiliency towards meeting the fetal/pup demand for DHA during pregnancy.

Omega-3 PUFA profoundly affect neural, physiological, and behavioural competences - implications for systemic changes in trophic interactions

In recent decades, much conceptual thinking in trophic ecology has been guided by theories of nutrient limitation and the flow of elements, such as carbon and nitrogen, within and among ecosystems. More recently, ecologists have also turned their attention to examining the value of specific dietary nutrients, in particular polyunsaturated fatty acids (PUFA), among which the omega-3 PUFA, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) play a central role as essential components of neuronal cell membranes in many organisms. This review focuses on a new neuro-ecological approach stemming from the biochemical (mechanistic) and physiological (functional) role of DHA in neuronal cell membranes, in particular in conjunction with G-protein coupled receptors (GPCRs). We link the co-evolution of these neurological functions to metabolic dependency on dietary omega-3 PUFA. We outline ways in which deficiencies in dietary DHA supply may affect, cognition, vision, and behaviour, and ultimately, the biological fitness of consumers. We then review emerging evidence that changes in access to dietary omega-3 PUFA may ultimately have profound impacts on trophic interactions leading to potential changes in community structure and ecosystem functioning that, in turn, may affect the supply of DHA within and across ecosystems, including the supply for human consumption.

Impact on cerebral function in rainbow trout fed with plant based omega-3 long chain polyunsaturated fatty acids enriched with DHA and EPA

Characterization and modulation of cerebral function by ω-3 long chain polyunsaturated fatty acids (ω-3 LC-PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) enrichment in plant based-diet were studied in rainbow trout (Oncorhynchus mikyss). We hypothesized that ω-3 LC-PUFAs are involved in the regulation of cerebral function in fish. During nine weeks, we examined the growth performance of rainbow trout for three experimental plant based-diets containing distinct levels of EPA and DHA. Using RT-qPCR, we assessed mRNA genes related to feeding behavior regulated by the central nervous system of humans, rodents and fish. These include markers of neuropeptides, indicators of cellular specification, animal stress, oxidant status, cytokines and genes regulating animal behaviour. ω-3 LC-PUFAs enrichment decreased daily food intake and induced a simultaneous mRNA expression increase in orexigenic transcript npy peptide and a decrease in anorexigen transcript pomcA peptide in the hypothalamus. Overall transcript genes related to proinflammatory cytokines, inflammation, antioxidant status, cortisol pathway, serotoninergic pathways and dopaminergic pathways were down-regulated in the juveniles fed the high ω-3 LC-PUFAs diet. However, the mRNA expression of transcripts related to cell specification were down regulated, namely tmem119 markers of microglial cell in forebrain and midbrain, gfap markers of astrocyte in the midbrain, and rbfox3 markers of neurons in the midbrain and hindbrain in juveniles fed high ω-3 experimental diet. In conclusion, this study revealed that a diet rich in ω-3 LC-PUFAs affected a relatively high proportion of the brain function in juvenile rainbow trout through mechanisms comparable to those characterized previously in mammals.

Aqueous extract of Dendrobium officinale confers neuroprotection against hypoxic-ischemic brain damage in neonatal rats

Accumulating evidences have proved the protective role of traditional Chinese medicine in improving neurological damage induced by cerebral hypoxia-ischemia. Herein, we hypothesized that Dendrobium officinale aqueous extract exerted neuroprotection against brain damage. Initially, a model of hypoxic-ischemic brain damage (HIBD) was induced in neonatal rats, which were subsequently intragastrically administered with different doses of Dendrobium officinale aqueous extract. Next, the antioxidant capacity was examined by enzyme-linked immunosorbent assay. 2,3,5-Triphenyltetrazolium chloride and terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling staining assays were adopted to determine neuronal apoptosis in brain tissues. Furthermore, neurotrophic factors and hypoxia-inducible factor-1α (HIF-1α) expression was identified by Western blot analysis. The neonatal rat models of HIBD presented impaired neurobehaviors and antioxidant capacity, increased neuronal apoptosis and expression of HIF-1α and histone deacetylase 1 (HDAC1), as well as diminished expression of neurotrophic factors and K⁺ -Cl^- -cotransporter 2 (KCC2). Notably, in response to different doses of Dendrobium officinale aqueous extract, the impairment on neurobehaviors and antioxidant capacity was alleviated, accompanied by reduced levels of nitric oxide synthase, nitric oxide, and malondialdehyde, and increased superoxide dismutase activity. Besides, the neuronal apoptosis was inhibited as reflected by down-regulated cleaved caspase-3 and Bax and up-regulated Bcl-2. Moreover, we also found accelerated expression of neurotrophic factors and KCC2 and diminished expression of HIF-1α and HDAC1. Altogether, this present study highlights that the aqueous extract of Dendrobium officinale can suppress the neuronal apoptosis and enhance the expression of neurotrophic factors to protect neonatal rats against HIBD.

A Novel Anti-Inflammatory Role of Omega-3 PUFAs in Prevention and Treatment of Atherosclerosis and Vascular Cognitive Impairment and Dementia

Atherosclerosis is an inflammatory chronic disease affecting arterial vessels and leading to vascular diseases, such as stroke and myocardial infarction. The relationship between atherosclerosis and risk of neurodegeneration has been established, in particular with vascular cognitive impairment and dementia (VCID). Systemic atherosclerosis increases the risk of VCID by inducing cerebral infarction, or through systemic or local inflammatory factors that underlie both atherosclerosis and cognition. Omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) are involved in inflammatory processes, but with opposite roles. Specifically, omega-3 PUFAs exert anti-inflammatory properties by competing with omega-6 PUFAs and displacing arachidonic acid in membrane phospholipids, decreasing the production of pro-inflammatory eicosanoids. Experimental studies and some clinical trials have demonstrated that omega-3 PUFA supplementation may reduce the risk of different phenotypes of atherosclerosis and cardiovascular disease. This review describes the link between atherosclerosis, VCID and inflammation, as well as how omega-3 PUFA supplementation may be useful to prevent and treat inflammatory-related diseases.

Maternal n-3 PUFAs deficiency during pregnancy inhibits neural progenitor cell proliferation in fetal rat cerebral cortex

The aim of this study was to evaluate the in vivo impacts of maternal n-3 polyunsaturated fatty acids (PUFAs) deficiency during pregnancy on the proliferation of neural progenitor cells (NPCs) in the developing cerebral cortex of fetal rats. Our results showed that about 5 weeks of maternal dietary n-3 PUFAs deprivation resulted in a substantial n-3 PUFA deficiency in fetal rat cerebral cortex. Importantly, by two survival schemes and two quantitative methods, we found that maternal intake of n-3 PUFAs deficient diet during the gestation significantly inhibited the proliferation of NPCs in fetal rat cerebral cortex. Moreover, the decreased cortical NPCs proliferation induced by nutritional n-3 PUFAs restriction did not originate from the increased NPCs apoptosis. Finally, our observations indicated that the down-regulation of cyclin E protein might be involved in the inhibitory effects of maternal n-3 PUFAs deficient diet on the proliferation of cortical NPCs. These findings highlight the importance of maternal intake of appropriate n-3 PUFAs and deepen our understanding of the exact effects of n-3 PUFAs on mammalian brain development.

Dietary Omega-3 Polyunsaturated Fatty Acid Deprivation Does Not Alter Seizure Thresholds but May Prevent the Anti-seizure Effects of Injected Docosahexaenoic Acid in Rats

Background: Brain concentrations of omega-3 docosahexaenoic acid (DHA, 22:6n-3) have been reported to positively correlate with seizure thresholds in rodent seizure models. It is not known whether brain DHA depletion, achieved by chronic dietary omega-3 polyunsaturated fatty acid (PUFA) deficiency, lowers seizure thresholds in rats.

Objective: The present study tested the hypothesis that lowering brain DHA concentration with chronic dietary n-3 PUFA deprivation in rats will reduce seizure thresholds, and that compared to injected oleic acid (OA), injected DHA will raise seizure thresholds in rats maintained on n-3 PUFA adequate and deficient diets.

Methods: Rats (60 days old) were surgically implanted with electrodes in the amygdala, and subsequently randomized to the AIN-93G diet containing adequate levels of n-3 PUFA derived from soybean oil or an n-3 PUFA-deficient diet derived from coconut and safflower oil. The rats were maintained on the diets for 37 weeks. Afterdischarge seizure thresholds (ADTs) were measured every 4–6 weeks by electrically stimulating the amygdala. Between weeks 35 and 37, ADTs were assessed within 1 h of subcutaneous OA or DHA injection (600 mg/kg). Seizure thresholds were also measured in a parallel group of non-implanted rats subjected to the maximal pentylenetetrazol (PTZ, 110 mg/kg) seizure test. PUFA composition was measured in the pyriform-amygdala complex of another group of non-implanted rats sacrificed at 16 and 32 weeks.

Results: Dietary n-3 PUFA deprivation did not significantly alter amygdaloid seizure thresholds or latency to PTZ-induced seizures. Acute injection of OA did not alter amygdaloid ADTs of rats on the n-3 PUFA adequate or deficient diets, whereas acute injection of DHA significantly increased amygdaloid ADTs in rats on the n-3 PUFA adequate control diet as compared to rats on the n-3 PUFA deficient diet (P < 0.05). Pyriform-amygdala DHA percent composition did not significantly differ between the groups, while n-6 docosapentaenoic acid, a marker of n-3 PUFA deficiency, was significantly increased by 2.9-fold at 32 weeks.

Conclusion: Chronic dietary n-3 PUFA deficiency does not alter seizure thresholds in rats, but may prevent the anti-seizure effects of DHA.

The combined impacts of docosahexaenoic acid, endurance physical exercise, and prolonged fasting on brain function

Docosahexaenoic acid (DHA), a long chain polyunsaturated fatty acid (PUFA) is highly enriched in the membrane phospholipids of the brain, neuronal tissue and retina. Accumulating evidence suggests that brain DHA is necessary for maintaining for optimal function of the cognition and the visual system, particularly the photoreceptor, the retina. Loss of brain DHA, especially during crucial brain development period, was highly associated with visual and cognitive defects. Here it would be addressed the effect of DHA on brain functions as assessed by spatial task performance using a first generation model which is similar to human nutrition case. And also, it was well known that prolonged fasting and energy restriction with endurance physical exercise stimulate cognitive function and brain function, which is caused by upregulated ketone body and upregulated brain-derived neurotropic factor (BDNF) responses. In the DHA intake or prolonged physical exercise, upregulated BDNF can activate mitochondrial biogenesis to elevate neuronal bioenergetics and enable synaptic formation. And it also can activate DNA repair in neurons. Further study on the mechanisms about the combine effects of supplementation of DHA and energy restriction on brain function is urgently needed in this area.

PEMT, Δ6 desaturase, and palmitoyldocosahexaenoyl phosphatidylcholine are increased in rats during pregnancy

DHA is important for fetal neurodevelopment. During pregnancy, maternal plasma DHA increases, but the mechanism is not fully understood. Using rats fed a fixed-formula diet (DHA as 0.07% total energy), plasma and liver were collected for fatty acid profiling before pregnancy, at 15 and 20 days of pregnancy, and 7 days postpartum. Phosphatidylethanolamine methyltransferase (PEMT) and enzymes involved in PUFA synthesis were examined in liver. Ad hoc transcriptomic and lipidomic analyses were also performed. With pregnancy, DHA increased in liver and plasma lipids, with a large increase in plasma DHA between day 15 and day 20 that was mainly attributed to an increase in 16:0/DHA phosphatidylcholine (PC) in liver (2.6-fold) and plasma (3.9-fold). Increased protein levels of Δ6 desaturase (FADS2) and PEMT at day 20 and increased Pemt expression and PEMT activity at day 15 suggest that during pregnancy, both DHA synthesis and 16:0/DHA PC synthesis are upregulated. Transcriptomic analysis revealed minor changes in the expression of genes related to phospholipid synthesis, but little insight on DHA metabolism. Hepatic PEMT appears to be the mechanism for increased plasma 16:0/DHA PC, which is supported by increased DHA biosynthesis based on increased FADS2 protein levels.

Fatty Acid-Binding Protein 5 at the Blood-Brain Barrier Regulates Endogenous Brain Docosahexaenoic Acid Levels and Cognitive Function

Fatty acid-binding protein 5 (FABP5) at the blood-brain barrier contributes to the brain uptake of docosahexaenoic acid (DHA), a blood-derived polyunsaturated fatty acid essential for maintenance of cognitive function. Given the importance of DHA in cognition, the aim of this study was to investigate whether deletion of FABP5 results in cognitive dysfunction and whether this is associated with reduced brain endothelial cell uptake of exogenous DHA and subsequent attenuation in the brain levels of endogenous DHA. Cognitive function was assessed in male and female FABP5^+/+ and FABP5^-/- mice using a battery of memory paradigms. FABP5^-/- mice exhibited impaired working memory and short-term memory, and these cognitive deficits were associated with a 14.7 ± 5.7% reduction in endogenous brain DHA levels. The role of FABP5 in the blood-brain barrier transport of DHA was assessed by measuring ¹⁴C-DHA uptake into brain endothelial cells and capillaries isolated from FABP5^+/+ and FABP5^-/- mice. In line with a crucial role of FABP5 in the brain uptake of DHA, ¹⁴C-DHA uptake into brain endothelial cells and brain capillaries of FABP5^-/- mice was reduced by 48.4 ± 14.5% and 14.0 ± 4.2%, respectively, relative to those of FABP5^+/+ mice. These results strongly support the hypothesis that FABP5 is essential for maintaining brain endothelial cell uptake of DHA, and that cognitive deficits observed in FABP5^-/- mice are associated with reduced CNS access of DHA.

SIGNIFICANCE STATEMENT

Genetic deletion of fatty acid-binding protein 5 (FABP5) in mice reduces uptake of exogenous docosahexaenoic acid (DHA) into brain endothelial cells and brain capillaries and reduces brain parenchymal levels of endogenous DHA. Therefore, FABP5 in the brain endothelial cell is a crucial contributor to the brain levels of DHA. Critically, lowered brain DHA levels in FABP5^-/- mice occurred in tandem with cognitive deficits in a battery of memory paradigms. This study provides evidence of a critical role for FABP5 in the maintenance of cognitive function via regulating the brain uptake of DHA, and suggests that upregulation of FABP5 in neurodegenerative diseases, where brain DHA levels are possibly diminished (e.g., Alzheimer's disease), may provide a novel therapeutic approach for restoring cognitive function.

The fatty acid profile of rainbow trout liver cells modulates their tolerance to methylmercury and cadmium

The polyunsaturated fatty acid (PUFA) composition of fish tissues, which generally reflects that of the diet, affects various cellular properties such as membrane structure and fluidity, energy metabolism and susceptibility to oxidative stress. Since these cellular parameters can play an important role in the cellular response to organic and inorganic pollutants, a variation of the PUFA supply might modify the toxicity induced by such xenobiotics. In this work, we investigated whether the cellular fatty acid profile has an impact on the in vitro cell sensitivity to two environmental pollutants: methylmercury and cadmium. Firstly, the fatty acid composition of the rainbow trout liver cell line RTL-W1 was modified by enriching the growth medium with either alpha-linolenic acid (ALA, 18:3n-3), eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3), linoleic acid (LA, 18:2n-6), arachidonic acid (AA, 20:4n-6) or docosapentaenoic acid (DPA, 22:5n-6). These modified cells and their control (no PUFA enrichment) were then challenged for 24h with increasing concentrations of methylmercury or cadmium. We observed that (i) the phospholipid composition of the RTL-W1 cells was profoundly modulated by changing the PUFA content of the growth medium: major modifications were a high incorporation of the supplemented PUFA in the cellular phospholipids, the appearance of direct elongation and desaturation metabolites in the cellular phospholipids as well as a change in the gross phospholipid composition (PUFA and monounsaturated fatty acid (MUFA) levels and n-3/n-6 ratio); (ii) ALA, EPA and DPA enrichment significantly protected the RTL-W1 cells against both methylmercury and cadmium; (iv) DHA enrichment significantly protected the cells against cadmium but not methylmercury; (v) AA and LA enrichment had no impact on the cell tolerance to both methylmercury and cadmium; (vi) the abundance of 20:3n-6, a metabolite of the n-6 biotransformation pathway, in phospholipids was negatively correlated to the cell tolerance to both methylmercury and cadmium. Overall, our results highlighted the importance of the fatty acid supply on the tolerance of fish liver cells to methylmercury and cadmium.

Docosahexaenoic Acid in Neural Signaling Systems

Docosahexaenoic acid has been conserved in neural signalling systems in the cephalopods, fish, amphibian, reptiles, birds, mammals, primates and humans. This extreme conservation, despite wide genomic changes over 500 million years, testifies to a uniqueness of this molecule in the brain. The brain selectively incorporates docosahexaenoic acid and its rate of incorporation into the developing brain has been shown to be greater than ten times more efficient than its synthesis from the omega 3 fatty acids of land plant origin. Data has now been published demonstrating a significant influence of dietary omega 3 fatty acids on neural gene expression. As docosahexaenoic acid is the only omega 3 fatty acid in the brain, it is likely that it is the ligand involved. The selective uptake, requirement for function and stimulation of gene expression would have conferred an advantage to a primate which separated from the chimpanzees in the forests and woodlands and sought a different ecological niche. In view of the paucity of docosahexaenoic acid in the land food chain it is likely that the advantage would have been gained from a lacustrine or marine coastal habitat with access to food rich in docosahexaenoic acid and the accessory micronutrients, such as iodine, zinc, copper, manganese and selenium, of importance in brain development and protection against peroxidation. Land agricultural development has, in recent time, come to dominate the human food chain. The decline in use and availability of aquatic resources is not considered important by Langdon (2006) as he considers the resource was not needed for human evolution and can be replaced from the terrestrial food chain. This notion is not supported by the biochemistry nor the molecular biology. He misses the point that the shoreline hypothesis is not just dependent on docosahexaenoic acid but also on the other accessory nutrients specifically required by the brain. Moreover he neglects the basic principle of Darwinian evolution. The well documented greater efficiency of preformed docosahexaenoic acid for brain incorporation during development would have conferred a distinct survival advantage over those without it. All terrestrial mammals lost brain capacity in relation to advancing increase in body size. The rise in mental ill health and brain disorders, to replace all other costs in the European list of burdens of ill health, (Andlin Sobocki et al., 2005) raises interesting questions as to its association with the reduced availability and consumption of marine and fresh water products. The threat posed by the continued rise in brain disorders also raises questions of importance to present and future food and agricultural policies.

Maternal Malnutrition in the Etiopathogenesis of Psychiatric Diseases: Role of Polyunsaturated Fatty Acids

Evidence from human studies indicates that maternal metabolic state and malnutrition dramatically influence the risk for developing psychiatric complications in later adulthood. In this regard, the central role of polyunsaturated fatty acids (PUFAs), and particularly n-3 PUFAs, is emerging considering that epidemiological evidences have established a negative correlation between n-3 PUFA consumption and development of mood disorders. These findings were supported by clinical studies indicating that low content of n-3 PUFAs in diet is linked to an increased susceptibility to psychiatric disorders. PUFAs regulate membrane fluidity and exert their central action by modulating synaptogenesis and neurotrophic factor expression, neurogenesis, and neurotransmission. Moreover, they are precursors of molecules implicated in modulating immune and inflammatory processes in the brain. Importantly, their tissue concentrations are closely related to diet intake, especially to maternal consumption during embryonal life, considering that their synthesis from essential precursors has been shown to be inefficient in mammals. The scope of this review is to highlight the possible mechanisms of PUFA functions in the brain during pre- and post-natal period and to evaluate their role in the pathogenesis of psychiatric diseases.

Reducing dietary intake of linoleic acid of mouse dams during lactation increases offspring brain n-3 LCPUFA content

Omega (n-)3 and n-6 long chain polyunsaturated fatty acids (LCPUFA) accumulation in the infant brain after birth is strongly driven by dietary supply of n-3 and n-6 LCPUFAs and their C18 precursors through breast milk or infant formula. n-3 LCPUFA accretion is associated with positive effects on neurodevelopmental outcome whereas high n-6 LCPUFA accumulation is considered disadvantageous. Maternal diet is crucial for breast milk fatty acid composition. Unfortunately, global increases in linoleic acid (C18:2n-6; LA) intake have dramatically increased n-6 LCPUFA and reduced n-3 LCPUFA availability for breastfed infants. We investigated the effects of reducing maternal dietary LA, or increasing n-3 LCPUFA, during lactation on milk and offspring brain fatty acids in mice. Offspring brain n-3 LCPUFA was higher following both interventions, although effects were mediated by different mechanisms. Because of competitive interactions between n-3 and n-6 fatty acids, lowering maternal LA intake may support neurodevelopment in breastfed infants.

Dietary n-3 PUFAs Deficiency Increases Vulnerability to Inflammation-Induced Spatial Memory Impairment

Dietary n-3 polyunsaturated fatty acids (PUFAs) are critical components of inflammatory response and memory impairment. However, the mechanisms underlying the sensitizing effects of low n-3 PUFAs in the brain for the development of memory impairment following inflammation are still poorly understood. In this study, we examined how a 2-month n-3 PUFAs deficiency from pre-puberty to adulthood could increase vulnerability to the effect of inflammatory event on spatial memory in mice. Mice were given diets balanced or deficient in n-3 PUFAs for a 2-month period starting at post-natal day 21, followed by a peripheral administration of lipopolysaccharide (LPS), a bacterial endotoxin, at adulthood. We first showed that spatial memory performance was altered after LPS challenge only in n-3 PUFA-deficient mice that displayed lower n-3/n-6 PUFA ratio in the hippocampus. Importantly, long-term depression (LTD), but not long-term potentiation (LTP) was impaired in the hippocampus of LPS-treated n-3 PUFA-deficient mice. Proinflammatory cytokine levels were increased in the plasma of both n-3 PUFA-deficient and n-3 PUFA-balanced mice. However, only n-3 PUFA-balanced mice showed an increase in cytokine expression in the hippocampus in response to LPS. In addition, n-3 PUFA-deficient mice displayed higher glucocorticoid levels in response to LPS as compared with n-3 PUFA-balanced mice. These results indicate a role for n-3 PUFA imbalance in the sensitization of the hippocampal synaptic plasticity to inflammatory stimuli, which is likely to contribute to spatial memory impairment.

Long-chain omega-3 fatty acids and the brain: a review of the independent and shared effects of EPA, DPA and DHA

Omega-3 polyunsaturated fatty acids (PUFAs) exhibit neuroprotective properties and represent a potential treatment for a variety of neurodegenerative and neurological disorders. However, traditionally there has been a lack of discrimination between the different omega-3 PUFAs and effects have been broadly accredited to the series as a whole. Evidence for unique effects of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and more recently docosapentaenoic acid (DPA) is growing. For example, beneficial effects in mood disorders have more consistently been reported in clinical trials using EPA; whereas, with neurodegenerative conditions such as Alzheimer’s disease, the focus has been on DHA. DHA is quantitatively the most important omega-3 PUFA in the brain, and consequently the most studied, whereas the availability of high purity DPA preparations has been extremely limited until recently, limiting research into its effects. However, there is now a growing body of evidence indicating both independent and shared effects of EPA, DPA and DHA. The purpose of this review is to highlight how a detailed understanding of these effects is essential to improving understanding of their therapeutic potential. The review begins with an overview of omega-3 PUFA biochemistry and metabolism, with particular focus on the central nervous system (CNS), where DHA has unique and indispensable roles in neuronal membranes with levels preserved by multiple mechanisms. This is followed by a review of the different enzyme-derived anti-inflammatory mediators produced from EPA, DPA and DHA. Lastly, the relative protective effects of EPA, DPA and DHA in normal brain aging and the most common neurodegenerative disorders are discussed. With a greater understanding of the individual roles of EPA, DPA and DHA in brain health and repair it is hoped that appropriate dietary recommendations can be established and therapeutic interventions can be more targeted and refined.

Pathways of polyunsaturated fatty acid utilization: implications for brain function in neuropsychiatric health and disease

Essential polyunsaturated fatty acids (PUFAs) have profound effects on brain development and function. Abnormalities of PUFA status have been implicated in neuropsychiatric diseases such as major depression, bipolar disorder, schizophrenia, Alzheimer's disease, and attention deficit hyperactivity disorder. Pathophysiologic mechanisms could involve not only suboptimal PUFA intake, but also metabolic and genetic abnormalities, defective hepatic metabolism, and problems with diffusion and transport. This article provides an overview of physiologic factors regulating PUFA utilization, highlighting their relevance to neuropsychiatric disease.

Polyunsaturated fatty acids and their metabolites in brain function and disease

The brain is highly enriched with fatty acids. These include the polyunsaturated fatty acids (PUFAs) arachidonic acid and docosahexaenoic acid, which are largely esterified to the phospholipid cell membrane. Once PUFAs are released from the membrane, they can participate in signal transduction, either directly or after enzymatic conversion to a variety of bioactive derivatives ('mediators'). PUFAs and their mediators regulate several processes within the brain, such as neurotransmission, cell survival and neuroinflammation, and thereby mood and cognition. PUFA levels and the signalling pathways that they regulate are altered in various neurological disorders, including Alzheimer's disease and major depression. Diet and drugs targeting PUFAs may lead to novel therapeutic approaches for the prevention and treatment of brain disorders.

Nutritional n-3 PUFAs deficiency during perinatal periods alters brain innate immune system and neuronal plasticity-associated genes

Low dietary intake of the n-3 polyunsaturated fatty acids (PUFAs) is a causative factor of neurodevelopmental disorders. However the mechanisms linking n-3 PUFAs low dietary intake and neurodevelopmental disorders are poorly understood. Microglia, known mainly for their immune function in the injured or infected brain, have recently been demonstrated to play a pivotal role in regulating maturation of neuronal circuits during normal brain development. Disruption of this role during the perinatal period therefore could significantly contribute to psychopathologies with a neurodevelopmental neurodevelopmental component. N-3 PUFAs, essential lipids and key structural components of neuronal membrane phospholipids, are highly incorporated in cell membranes during the gestation and lactation phase. We previously showed that in a context of perinatal n-3 PUFAs deficiency, accretion of these latter is decreased and this is correlated to an alteration of endotoxin-induced inflammatory response. We thus postulated that dietary n-3 PUFAs imbalance alters the activity of microglia in the developing brain, leading to abnormal formation of neuronal networks. We first confirmed that mice fed with a n-3 PUFAs deficient diet displayed decreased n-3 PUFAs levels in the brain at post-natal days (PND)0 and PND21. We then demonstrated that n-3 PUFAs deficiency altered microglia phenotype and motility in the post-natal developing brain. This was paralleled by an increase in pro-inflammatory cytokines expression at PND21 and to modification of neuronal plasticity-related genes expression. Overall, our findings show for the first time that a dietary n-3 PUFAs deficiency from the first day of gestation leads to the development of a pro-inflammatory condition in the central nervous system that may contribute to neurodevelopmental alterations.

n-3 LCPUFA improves cognition: the young, the old and the sick

Due to the implication of docosahexaenoic acid (DHA) in neurogenesis, synaptogenesis, neurite outgrowth and to its high incorporation into the brain, this n-3 long chain polyunsaturated fatty acid (LCPUFA) is considered as crucial in the development and maintenance of the learning memory performance throughout life. In the present chapter we aimed at reviewing data investigating the relation between DHA and cognition during the perinatal period, young adult- and adulthood and neurodegenerative diseases such as Alzheimer disease (AD). In Humans, dietary DHA supplementation from the perinatal period to adulthood does not reveal a clear and consistent memory improvement whereas it is the case in animal studies. The positive effects observed in animal models may have been enhanced by using n-3 PUFA deficient animal models as controls. In animal models of AD, a general consensus on the beneficial effects of n-3 LCPUFA in attenuating cognitive impairment was established. These studies make DHA a potential suitable micronutrient for the maintenance of cognitive performance at all periods of life.

Depletion of brain docosahexaenoic acid impairs recovery from traumatic brain injury

Omega-3 fatty acids are crucial for proper development and function of the brain where docosahexaenoic acid (DHA), the primary omega-3 fatty acid in the brain, is retained avidly by the neuronal membranes. We investigated the effect of DHA depletion in the brain on the outcome of traumatic brain injury (TBI). Pregnant mice were put on an omega-3 fatty acid adequate or deficient diet from gestation day 14 and the pups were raised on the respective diets. Continuation of this dietary regime for three generations resulted in approximately 70% loss of DHA in the brain. Controlled cortical impact was delivered to both groups of mice to produce severe TBI and the functional recovery was compared. Compared to the omega-3 adequate mice, the DHA depleted mice exhibited significantly slower recovery from motor deficits evaluated by the rotarod and the beam walk tests. Furthermore, the DHA deficient mice showed greater anxiety-like behavior tested in the open field test as well as cognitive deficits evaluated by the novel object recognition test. The level of alpha spectrin II breakdown products, the markers of TBI, was significantly elevated in the deficient mouse cortices, indicating that the injury is greater in the deficient brains. This observation was further supported by the reduction of NeuN positive cells around the site of injury in the deficient mice, indicating exacerbated neuronal death after injury. These results suggest an important influence of the brain DHA status on TBI outcome.

Dietary omega-3 deficiency reduces BDNF content and activation NMDA receptor and Fyn in dorsal hippocampus: implications on persistence of long-term memory in rats

Omega-3 (n-3) fatty acids are important for adequate brain function and cognition. The aim of the present study was to evaluate how n-3 fatty acids influence the persistence of long-term memory (LTM) in an aversive memory task and to explore the putative mechanism involved. Female rats received isocaloric diets that included n-3 (n-3 group) or not (D group). The adult litters were subjected to an inhibitory avoidance task (0.7 mA, 1.0 seconds foot shock) to elicit persistent LTM. Twelve hours after the training session, the fatty acid profile and the brain derived neurotrophic factor (BDNF) content of the dorsal hippocampus were assessed. In addition, we measured the activation of the NR2B subunit of the N-methyl-d-aspartate (NMDA) receptor and the SRC family protein Fyn. Despite pronounced learning in both groups, the persistence of LTM was abolished in the D group 7 days after the training session. We also observed that the D group presented reductions in hippocampal DHA (22:6 n-3) and BDNF content. Twelve hours after the training session, the D group showed decreased NR2B and Fyn phosphorylation in the dorsal hippocampus, with no change in the total content of these proteins. Further, there was a decrease in the interaction of Fyn with NR2B in the D group, as observed by co-immunoprecipitation. Taken together, these data suggest that n-3 fatty acids influence the persistence of LTM by maintaining adequate levels of DHA and BDNF as well as by influencing the activation of NR2B and Fyn during the period of memory formation.

Does docosahexaenoic acid supplementation in term infants enhance neurocognitive functioning in infancy?

The proposal that dietary docosahexaenoic acid (DHA) enhances neurocognitive functioning in term infants is controversial. Theoretical evidence, laboratory research and human epidemiological studies have convincingly demonstrated that DHA deficiency can negatively impact neurocognitive development. However, the results from randomized controlled trials (RCTs) of DHA supplementation in human term-born infants have been inconsistent. This article will (i) discuss the role of DHA in the human diet, (ii) explore the physiological mechanisms by which DHA plausibly influences neurocognitive capacity, and (iii) seek to characterize the optimal intake of DHA during infancy for neurocognitive functioning, based on existing research that has been undertaken in developed countries (specifically, within Australia). The major observational studies and RCTs that have examined dietary DHA in human infants and animals are presented, and we consider suggestions that DHA requirements vary across individuals according to genetic profile. It is important that the current evidence concerning DHA supplementation is carefully evaluated so that appropriate recommendations can be made and future directions of research can be strategically planned.

Metabolomics uncovers dietary omega-3 fatty acid-derived metabolites implicated in anti-nociceptive responses after experimental spinal cord injury

Chronic neuropathic pain is a frequent comorbidity following spinal cord injury (SCI) and often fails to respond to conventional pain management strategies. Preventive administration of docosahexaenoic acid (DHA) or the consumption of a diet rich in omega-3 polyunsaturated fatty acids (O3PUFAs) confers potent prophylaxis against SCI and improves functional recovery. The present study examines whether this novel dietary strategy provides significant antinociceptive benefits in rats experiencing SCI-induced pain. Rats were fed control chow or chow enriched with O3PUFAs for 8weeks before being subjected to sham or cord contusion surgeries, continuing the same diets after surgery for another 8 more weeks. The paw sensitivity to noxious heat was quantified for at least 8weeks post-SCI using the Hargreaves test. We found that SCI rats consuming the preventive O3PUFA-enriched diet exhibited a significant reduction in thermal hyperalgesia compared to those consuming the normal diet. Functional neurometabolomic profiling revealed a distinctive deregulation in the metabolism of endocannabinoids (eCB) and related N-acyl ethanolamines (NAEs) at 8weeks post-SCI. We found that O3PUFAs consumption led to a robust accumulation of novel NAE precursors, including the glycerophospho-containing docosahexaenoyl ethanolamine (DHEA), docosapentaenoyl ethanolamine (DPEA), and eicosapentaenoyl ethanolamine (EPEA). The tissue levels of these metabolites were significantly correlated with the antihyperalgesic phenotype. In addition, rats consuming the O3PUFA-rich diet showed reduced sprouting of nociceptive fibers containing CGRP and dorsal horn neuron p38 mitogen-activated protein kinase (MAPK) expression, well-established biomarkers of pain. The spinal cord levels of inositols were positively correlated with thermal hyperalgesia, supporting their role as biomarkers of chronic neuropathic pain. Notably, the O3PUFA-rich dietary intervention reduced the levels of these metabolites. Collectively, these results demonstrate the prophylactic value of dietary O3PUFA against SCI-mediated chronic pain.

The relationship of docosahexaenoic acid (DHA) with learning and behavior in healthy children: a review

Childhood is a period of brain growth and maturation. The long chain omega-3 fatty acid, docosahexaenoic acid (DHA), is a major lipid in the brain recognized as essential for normal brain function. In animals, low brain DHA results in impaired learning and behavior. In infants, DHA is important for optimal visual and cognitive development. The usual intake of DHA among toddlers and children is low and some studies show improvements in cognition and behavior as the result of supplementation with polyunsaturated fatty acids including DHA. The purpose of this review was to identify and evaluate current knowledge regarding the relationship of DHA with measures of learning and behavior in healthy school-age children. A systematic search of the literature identified 15 relevant publications for review. The search found studies which were diverse in purpose and design and without consistent conclusions regarding the treatment effect of DHA intake or biomarker status on specific cognitive tests. However, studies of brain activity reported benefits of DHA supplementation and over half of the studies reported a favorable role for DHA or long chain omega-3 fatty acids in at least one area of cognition or behavior. Studies also suggested an important role for DHA in school performance.

Breastfeeding may protect against persistent stuttering

PURPOSE

This study investigated the hypothesis that breastfeeding in infancy might protect against persistent stuttering in children.

METHOD

We collected new data from the mothers of current and past participants in the Illinois Stuttering Research Program on their children's feeding history during infancy. We obtained 47 usable responses, for 17 children with persistent stuttering and 30 children who recovered naturally after a period of stuttering.

RESULTS

A chi-squared test for linear trend revealed a significant relationship between breastfeeding duration and the likelihood of natural recovery for the boys in the sample. Mothers of children in the persistent group were no more likely to report early feeding difficulties which might have suggested an underlying oral motor deficit in children predisposed toward persistent stuttering.

CONCLUSIONS

Our results offer preliminary support for the idea that breastfeeding may confer a measure of protection against persistent stuttering. The fatty acid profile of human milk, with its potential to affect both gene expression and the composition of neural tissue, may explain this association. Further research is called for.

LEARNING OUTCOMES

The reader will be able to discuss at least one reason why human milk may make a difference in neurodevelopment generally and with regard to stuttering outcomes specifically. Additionally, the reader will be able to describe the relationship between breastfeeding duration and stuttering recovery observed in this sample.

N-Docosahexaenoylethanolamine is a potent neurogenic factor for neural stem cell differentiation

Docosahexaenoic acid (DHA) has been shown to promote neuronal differentiation of neural stem cells (NSCs) in vivo and in vitro. Previously, we found that N-docosahexaenoylethanolamine (synaptamide), an endogenous DHA metabolite with an endocannabinoid-like structure, promotes neurite growth, synaptogenesis, and synaptic function. In this study, we demonstrate that synaptamide potently induces neuronal differentiation of NSCs. Differentiating NSCs were capable of synthesizing synaptamide from DHA. Treatment of NSCs with synaptamide at low nanomolar concentrations significantly increased the number of MAP2 and Tuj-1-positive neurons with concomitant induction of protein kinase A (PKA)/cAMP response element binding protein (CREB) phosphorylation. Conversely, PKA inhibitors or PKA knockdown abolished the synaptamide-induced neuronal differentiation of NSCs. URB597, a fatty acid amide hydrolase (FAAH) inhibitor, elevated the level of DHA-derived synaptamide and further potentiated the DHA- or synaptamide-induced neuronal differentiation of NSCs. Similarly, NSCs obtained from FAAH KO mice exhibited greater capacity to induce neuronal differentiation in response to DHA or synaptamide compared to the wild type NSCs. Neither synaptamide nor DHA affected NSC differentiation into GFAP-positive glia cells. These results suggest that endogenously produced synaptamide is a potent mediator for neurogenic differentiation of NSCs acting through PKA/CREB activation.

Maternal long-chain PUFA supplementation during protein deficiency improves brain fatty acid accretion in rat pups by altering the milk fatty acid composition of the dam

Long-chain PUFA (LC-PUFA) are important for fetal and neonatal brain development. However, their accretion in the brain is compromised during maternal protein restriction. Hence, we investigated the effect of maternal supplementation with n-3 DHA plus n-6 arachidonic acid (ARA) at a low protein level (9 %) on offspring brain fatty acid accretion using Wistar rats (nine rats per group) randomly fed a control (C), a low-protein (LP) or a low-protein DHA + ARA-supplemented (LPS) diet during gestation and lactation. At birth, pups from the LPS group had the highest brain DHA and n-3 fatty acid levels (P = 0·001), whereas pups from the LP group had the highest MUFA (P = 0·05) but the lowest DHA and total n-3 PUFA levels (P = 0·000). During lactation, pups from the LPS group accrued significantly more α-linolenic acid (P = 0·003), EPA (P = 0·02) and DHA (P = 0·000) in brain lipids than pups from the LP group, whereas brain lipids of pups from the LP group had markedly increased levels of the n-3 deficiency marker docosapentaenoic acid and n-6:n-3 ratio (P = 0·000). Owing to supplementation, milk from LPS dams had the highest DHA and ARA, but lower SCFA and medium-chain fatty acids as compared with milk from C and LP dams during early lactation, but normalised by mid-lactation. To conclude, adverse effects of restricted maternal protein intake on LC-PUFA accretion in the brain of offspring were ameliorated by alterations in maternal milk fatty acid profile due to supplementation. Results underscore the importance of LC-PUFA for protein-deficient mothers during gestation as well as lactation to achieve the optimum brain LC-PUFA status of progeny.

Effect of culture conditions on growth, lipid content, and fatty acid composition of Aurantiochytrium mangrovei strain BL10

This study explored the influence of various culture conditions on the biomass, lipid content, production of docosahexaenoic acid (DHA), and fatty acid composition of Aurantiochytrium mangrovei strain BL10. The variables examined in this study include the species and concentration of salt, the concentrations of the two substrates glucose and yeast extract, the level of dissolved oxygen, the cerulenin treatment, and the stages of BL10 growth. Our results demonstrate that BL10 culture produces maximum biomass when salinity levels are between 0.2 and 3.0%. Decreasing salinity to 0.1% resulted in a considerable decrease in the biomass, lipid content, DHA production, and DHA to palmitic acid (PA) (DHA/PA) ratio, signifying deterioration in the quality of the oil produced. The addition of 0.9% sodium sulfate to replenish salinity from 0.1% to 1.0% successfully recovered biomass, lipid content and DHA production levels; however, this also led to a decrease in DHA/PA ratio. An increase in oxygen and cerulenin levels resulted in a concomitant decrease in the DHA to docosapentaenoic acid (DPA) (DHA/DPA) ratio in BL10 oil. Furthermore, the DHA/DPA and DHA/PA ratios varied considerably before and after the termination of cell division, which occurred around the 24 hour mark. These results could serve as a foundation for elucidating the biochemistry underlying the accumulation of lipids, and a definition of the extrinsic (environmental or nutritional) and intrinsic (cell growth stage) factors that influence lipid quality and the production of DHA by BL10.

Cognitive enhancement by omega-3 fatty acids from child-hood to old age: findings from animal and clinical studies

Omega-(n)-3 polyunsaturated fatty acids (PUFAs), including docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are major components of neuronal membranes and have a wide range of functions, from modulating synaptic plasticity and neurochemistry, to neuroimmune-modulation and neuroprotection. Thus, it is not surprising that n-3 PUFA are widely acknowledged to have cognitive-enhancing effects. Although clinical evidence is somewhat conflicting, probably in large part due to methodological issues, animal studies have consistently demonstrated that n-3 PUFA are indispensable for proper brain development, may enhance cognitive function in healthy, adult individuals and attenuate cognitive impairment in aging and age-related disorders, such as dementia. This review discusses and integrates up to date evidence from clinical and animal studies investigating the cognitive-enhancing effects of n-3 PUFA during development, child- and adult-hood, as well as old-age with associated neurodegenerative diseases, such as Alzheimer's disease. Furthermore, we cover the major underlying biochemical and neurophysiological mechanisms by which n-3 PUFA mediate these effects on cognition. This article is part of a Special Issue entitled 'Cognitive Enhancers'.

Enzymes in brain phospholipid docosahexaenoic acid accretion: a PL-ethora of potential PL-ayers

Neural tissue is highly enriched in docosahexaenoic acid (DHA) that is primarily found in the sn-2 position of ethanolamine-containing phospholipids and plasmalogens. Current knowledge on the activity of enzymes in brain phospholipid synthesis does not fully explain this composition and stereospecificity. It is likely that a host of enzyme-mediated processes play roles in brain DHA accumulation to develop this unique enrichment and phospholipid profile. This review examines current knowledge on the spectrum of enzymes that may be involved in brain DHA uptake and utilization in the synthesis and remodeling of phospholipids. It also highlights gaps in that knowledge, including missing information on the activity of known brain enzymes towards DHA as a substrate, and missing identities of brain enzymes that catalyze orphan reactions utilizing DHA for phospholipid formation.

Quantifying the differential effects of DHA and DPA on the early events in visual signal transduction

A range of evidence from animal, clinical and epidemiological studies indicates that highly polyunsaturated acyl chains play important roles in development, cognition, vision and other aspects of neurological function. In a number of these studies n3 polyunsaturated fatty acids (PUFAs) appear to be more efficacious than n6 PUFAs. In a previous study of retinal rod outer segments obtained from rats raised on either an n3 adequate or deficient diet, we demonstrated that the replacement of 22:6n3 by 22:5n6 in the n3 deficient rats led to functional deficits in each step in the visual signaling process (Niu et al., 2004). In this study, we examined rhodopsin and phosphodiesterase function and acyl chain packing properties in membranes consisting of phosphatidylcholines with sn-1=18:0, and sn-2=22:6n3, 22:5n6, or 22:5n3 in order to determine if differences in function are due to the loss of one double bond or due to differences in double bond location. At 37 °C the n6 lipid shifted the equilibrium between the active metarhodopsin II (MII) state and inactive metarhodopsin I (MI) state towards MI. In addition, 22:5n6 reduced the rates of MII formation and MII-transducin complex formation by 2- and 6-fold, respectively. At a physiologically relevant level of rhodopsin light stimulation, the activity of phosphodiesterase was reduced by 50% in the 22:5n6 membrane, relative to either of the n3 membranes. Activity levels in the two n3 membranes were essentially identical. Ensemble acyl chain order was assessed with time-resolved fluorescence measurements of the membrane probe diphenylhexatriene (DPH). Analysis in terms of the orientational distribution of DPH showed that acyl chain packing in the two n3 membranes is quite similar, while in the 22:5n6 membrane there was considerably less packing disorder in the bilayer midplane. These results demonstrate that the n3 bond configuration uniquely optimizes the early steps in signaling via a mechanism which may involve acyl chain packing deep in the bilayer.

SPECIES-SPECIFIC VARIATION IN FATTY ACID CONCENTRATIONS OF FOUR PHYTOPLANKTON SPECIES: DOES PHOSPHORUS SUPPLY INFLUENCE THE EFFECT OF LIGHT INTENSITY OR TEMPERATURE?(1)

We tested, in the laboratory, the influence of light intensity, temperature, and phosphorus (P) supply on fatty acid (FA) concentrations of four freshwater algae: the green algae Scenedesmus quadricauda (Turpin) Bréb. and Chlamydomonas globosa J. Snow, the cryptophyte Cryptomonas ovata Ehrenb., and the diatom Cyclotella meneghiniana Kütz. We investigated the main and interactive effects of two variables on algal FA concentrations (i.e., light intensity and P supply or temperature and P supply). Interactive effects of light intensity and P supply were most pronounced in C. meneghiniana, but were also found in S. quadricauda and C. ovata. Changes in several saturated and unsaturated FA concentrations with light were more distinct in the low-P treatments than in the high-P treatments. Interactive effects of temperature and P supply on various FA concentrations were observed in all four species, but there was no consistent pattern. In lake ecosystems, P limitation often coincides with high light intensities and temperatures in summer. Therefore, it is important to examine how combinations of these environmental conditions affect FA concentrations of primary producers that are important sources of FAs for higher trophic levels.

Docosahexaenoic acid signalolipidomics in nutrition: significance in aging, neuroinflammation, macular degeneration, Alzheimer's, and other neurodegenerative diseases

Essential polyunsaturated fatty acids (PUFAs) are critical nutritional lipids that must be obtained from the diet to sustain homeostasis. Omega-3 and -6 PUFAs are key components of biomembranes and play important roles in cell integrity, development, maintenance, and function. The essential omega-3 fatty acid family member docosahexaenoic acid (DHA) is avidly retained and uniquely concentrated in the nervous system, particularly in photoreceptors and synaptic membranes. DHA plays a key role in vision, neuroprotection, successful aging, memory, and other functions. In addition, DHA displays anti-inflammatory and inflammatory resolving properties in contrast to the proinflammatory actions of several members of the omega-6 PUFAs family. This review discusses DHA signalolipidomics, comprising the cellular/tissue organization of DHA uptake, its distribution among cellular compartments, the organization and function of membrane domains rich in DHA-containing phospholipids, and the cellular and molecular events revealed by the uncovering of signaling pathways regulated by DHA and docosanoids, the DHA-derived bioactive lipids, which include neuroprotectin D1 (NPD1), a novel DHA-derived stereoselective mediator. NPD1 synthesis agonists include neurotrophins and oxidative stress; NPD1 elicits potent anti-inflammatory actions and prohomeostatic bioactivity, is anti-angiogenic, promotes corneal nerve regeneration, and induces cell survival. In the context of DHA signalolipidomics, this review highlights aging and the evolving studies on the significance of DHA in Alzheimer's disease, macular degeneration, Parkinson's disease, and other brain disorders. DHA signalolipidomics in the nervous system offers emerging targets for pharmaceutical intervention and clinical translation.

Dietary n-3 polyunsaturated fatty acid deprivation together with early maternal separation increases anxiety and vulnerability to stress in adult rats

Low concentrations of n-3 polyunsaturated fatty acid (PUFA) and chronic stress are implicated in susceptibility to mood disorders. We have investigated the combined effects of chronic n-3 PUFA dietary deficiency and early maternal separation (MS) stress on the reactivity to stressful situations of rats as adults. Pups fed a control or an n-3 PUFA deficient diet were daily separated for two weeks before weaning They were all tested at 3 month-old to determine their anxiety, and their ability to learn two aversive tasks differing in the control they could exert on the situation: auditory fear conditioning and brightness avoidance discrimination. Neither the n-3 PUFA-deficient diet nor MS alone significantly affected behavior. But n-3 PUFA-deficient rats that had been separated were more anxious and fearful in inescapable situations, while their ability to cope with an aversive avoidance task remained unaffected. These results support the notion that PUFA-unbalanced diet, together with stress, may be a determinant risk factor in emotional disorders.