Gene expression and molecular composition of phospholipids in rat brain in relation to dietary n-6 to n-3 fatty acid ratio

Omega-3 polyunsaturated fatty acids and Parkinson's disease: A systematic review of animal studies

Parkinson's disease (PD) is the second most common neurodegenerative disorder. The primary pathological features of PD include the presence of α-synuclein aggregates and Lewy bodies, mitochondrial dysfunction, oxidative stress, and neuroinflammation. Recently, omega-3 fatty acids (ω-3 PUFAs) have been under investigation as a preventive and/or therapeutic strategy for PD, primarily owing to their antioxidant and anti-inflammatory properties. Therefore, the objective of this study was to conduct a systematic review of the literature, focusing on studies that assessed the effects of ω-3 PUFAs in rodent models mimicking human PD. The search was performed using the terms "Parkinson's disease," "fish oil," "omega 3," "docosahexaenoic acid," and "eicosapentaenoic acid" across databases PUBMED, Web of Science, Science Direct, Scielo, and Google Scholar. Following analysis based on predefined inclusion and exclusion criteria, 39 studies were included. Considering behavioral parameters, pathological markers of the disease, quantification of ω-3 PUFAs in the brain, as well as anti-inflammatory, antioxidant, and anti-apoptotic effects, it can be observed that ω-3 PUFAs exhibit a potential neuroprotective effect in PD. In summary, this systematic review presents significant scientific evidence regarding the effects and mechanisms underlying the neuroprotective properties of ω-3 PUFAs, offering valuable insights for the development of future clinical investigations.

Lipids and Secretory Vesicle Exocytosis

In recent years, the number of studies implicating lipids in the regulation of synaptic vesicle exocytosis has risen considerably. It has become increasingly clear that lipids such as phosphoinositides, lysophospholipids, cholesterol, arachidonic acid and myristic acid play critical regulatory roles in the processes leading up to exocytosis. Lipids may affect membrane fusion reactions by altering the physical properties of the membrane, recruiting key regulatory proteins, concentrating proteins into exocytic "hotspots" or by modulating protein functions allosterically. Discrete changes in phosphoinositides concentration are involved in multiple trafficking events including exocytosis and endocytosis. Lipid-modifying enzymes such as the DDHD2 isoform of phospholipase A1 were recently shown to contribute to memory acquisition via dynamic modifications of the brain lipid landscape. Considering the increasing reports on neurodegenerative disorders associated with aberrant intracellular trafficking, an improved understanding of the control of lipid pathways is physiologically and clinically significant and will afford unique insights into mechanisms and therapeutic methods for neurodegenerative diseases. Consequently, this chapter will discuss the different classes of lipids, phospholipase enzymes, the evidence linking them to synaptic neurotransmitter release and how they act to regulate key steps in the multi-step process leading to neuronal communication and memory acquisition.

Altered Cord Blood Lipid Concentrations Correlate with Birth Weight and Doppler Velocimetry of Fetal Vessels in Human Fetal Growth Restriction Pregnancies

Fetal growth restriction (FGR) is associated with short- and long-term morbidity, often with fetal compromise in utero, evidenced by abnormal Doppler velocimetry of fetal vessels. Lipids are vital for growth and development, but metabolism in FGR pregnancy, where fetuses do not grow to full genetic potential, is poorly understood. We hypothesize that triglyceride concentrations are increased in placentas and that important complex lipids are reduced in cord plasma from pregnancies producing the smallest babies (birth weight < 5%) and correlate with ultrasound Dopplers. Dopplers (umbilical artery, UA; middle cerebral artery, MCA) were assessed longitudinally in pregnancies diagnosed with estimated fetal weight (EFW) < 10% at ≥29 weeks gestation. For a subset of enrolled women, placentas and cord blood were collected at delivery, fatty acids were extracted and targeted lipid class analysis (triglyceride, TG; phosphatidylcholine, PC; lysophosphatidylcholine, LPC; eicosanoid) performed by LCMS. For this sub-analysis, participants were categorized as FGR (Fenton birth weight, BW ≤ 5%) or SGA "controls" (Fenton BW > 5%). FGRs (n = 8) delivered 1 week earlier (p = 0.04), were 29% smaller (p = 0.002), and had 133% higher UA pulsatility index (PI, p = 0.02) than SGAs (n = 12). FGR plasma TG, free arachidonic acid (AA), and several eicosanoids were increased (p < 0.05); docosahexaenoic acid (DHA)-LPC was decreased (p < 0.01). Plasma TG correlated inversely with BW (p < 0.05). Plasma EET, non-esterified AA, and DHA correlated inversely with BW and directly with UA PI (p < 0.05). Placental DHA-PC and AA-PC correlated directly with MCA PI (p < 0.05). In fetuses initially referred for inadequate fetal growth (EFW < 10%), those with BW ≤ 5% demonstrated distinctly different cord plasma lipid profiles than those with BW > 5%, which correlated with Doppler PIs. This provides new insights into fetal lipidomic response to the FGR in utero environment. The impact of these changes on specific processes of growth and development (particularly fetal brain) have not been elucidated, but the relationship with Doppler PI may provide additional context for FGR surveillance, and a more targeted approach to nutritional management of these infants.

Short-term supplementation of EPA-enriched ethanolamine plasmalogen increases the level of DHA in the brain and liver of n-3 PUFA deficient mice in early life after weaning

A lack of n-3 polyunsaturated fatty acids (PUFAs) in mothers' diet significantly reduced the amount of docosahexaenoic acid (DHA) in the brains of offspring, which might affect their brain function. Our previous research has proven multiple benefits of eicosapentaenoic acid (EPA)-enriched ethanolamine plasmalogen (pPE) in enhancing the learning and memory ability. However, the effect of dietary supplementation with EPA-pPE on the DHA content in the brain and liver of offspring lacking n-3 PUFAs in early life is still unclear. Female ICR mice were fed with n-3 PUFA-deficient diets throughout the gestation and lactation periods to get n-3 PUFA-deficient offspring. The lipid profiles in the cerebral cortex and liver of offspring were analyzed using lipidomics after dietary supplementation with EPA-pPE (0.05%, w/w) and EPA-phosphatidylcholine (PC) (0.05%, w/w) for 2 weeks after weaning. Dietary supplementation with EPA could significantly change fatty acid composition in a variety of phospholipid molecular species compared with the n-3 deficient group. EPA-pPE and EPA-PC remarkably increased the DHA content in the brain PC, ether-linked phosphatidylcholine (ePC), and phosphatidylethanolamine plasmalogen (pPE) and liver triglyceride (TG), lyso-phosphatidylcholine (LPC), ePC, phosphatidylethanolamine (PE), and pPE molecular species, in which EPA-pPE showed more significant effects on the increase of DHA in cerebral cortex PC, ePC and liver PC compared with EPA-PC. Both EPA-phospholipids could effectively increase the DHA levels, and the pPE form was superior to PC in the contribution of DHA content in the cerebral cortex PC, ePC and liver PC molecular species. EPA-enriched ethanolamine plasmalogen might be a good nutritional supplement to increase DHA levels in the brains of n-3 PUFA-deficient offspring.

Improvement of Oxidative Stress and Mitochondrial Dysfunction by β-Caryophyllene: A Focus on the Nervous System

Mitochondrial dysfunction results in a series of defective cellular events, including decreased adenosine triphosphate (ATP) production, enhanced reactive oxygen species (ROS) output, and altered proteastasis and cellular quality control. An enhanced output of ROS may damage mitochondrial components, such as mitochondrial DNA and elements of the electron transport chain, resulting in the loss of proper electrochemical gradient across the mitochondrial inner membrane and an ensuing shutdown of mitochondrial energy production. Neurons have an increased demand for ATP and oxygen, and thus are more prone to damage induced by mitochondrial dysfunction. Mitochondrial dysfunction, damaged electron transport chains, altered membrane permeability and Ca²⁺ homeostasis, and impaired mitochondrial defense systems induced by oxidative stress, are pathological changes involved in neurodegenerative disorders. A growing body of evidence suggests that the use of antioxidants could stabilize mitochondria and thus may be suitable for preventing neuronal loss. Numerous natural products exhibit the potential to counter oxidative stress and mitochondrial dysfunction; however, science is still looking for a breakthrough in the treatment of neurodegenerative disorders. β-caryophyllene is a bicyclic sesquiterpene, and an active principle of essential oils derived from a large number of spices and food plants. As a selective cannabinoid receptor 2 (CB2) agonist, several studies have reported it as possessing numerous pharmacological activities such as antibacterial (e.g., Helicobacter pylori), antioxidant, anti-inflammatory, analgesic (e.g., neuropathic pain), anti-neurodegenerative and anticancer properties. The present review mainly focuses on the potential of β-caryophyllene in reducing oxidative stress and mitochondrial dysfunction, and its possible links with neuroprotection.

Dietary alpha linolenic acid in pregnant mice and during weaning increases brain docosahexaenoic acid and improves recognition memory in the offspring

Docosahexaenoic acid (DHA) is critical for normal brain development and function. DHA is in danger of being significantly reduced in the human food supply, and the question of whether its metabolic precursor, the essential n-3 alpha linolenic acid (ALA) during pregnancy, can support fetal brain DHA levels for optimal neurodevelopment, is fundamental. Female mice were fed either ALA-enriched or Control diet during pregnancy and lactation. The direct effect of maternal dietary ALA on lipids was analyzed in liver, red blood cells, brain and brain vasculature, together with genes of fatty acid metabolism and transport in three-week-old offspring. The long-term effect of maternal dietary ALA on brain fatty acids and memory was studied in 19-week-old offspring. Three-week-old ALA offspring showed higher levels of n-3 fatty acids in liver, red blood cell, blood-brain barrier (BBB) vasculature and brain parenchyma, DHA enrichment in brain phospholipids and higher gene and protein expression of the DHA transporter, major facilitator superfamily domain containing 2a, compared to Controls. 19-week-old ALA offspring showed higher brain DHA levels and better memory performance than Controls. The increased brain DHA levels induced by maternal dietary ALA during pregnancy-lactation, together with the up-regulated levels of major facilitator superfamily domain containing 2a, may indicate a mode for greater DHA uptake with long-term impact on better memory in ALA offspring.

Phospholipases in neuronal function: A role in learning and memory?

Despite the human brain being made of nearly 60% fat, the vast majority of studies on the mechanisms of neuronal communication which underpin cognition, memory and learning, primarily focus on proteins and/or (epi)genetic mechanisms. Phospholipids are the main component of all cellular membranes and function as substrates for numerous phospholipid-modifying enzymes, including phospholipases, which release free fatty acids (FFAs) and other lipid metabolites that can alter the intrinsic properties of the membranes, recruit and activate critical proteins, and act as lipid signalling molecules. Here, we will review brain specific phospholipases, their roles in membrane remodelling, neuronal function, learning and memory, as well as their disease implications. In particular, we will highlight key roles of unsaturated FFAs, particularly arachidonic acid, in neurotransmitter release, neuroinflammation and memory. In light of recent findings, we will also discuss the emerging role of phospholipase A₁ and the creation of saturated FFAs in the brain.

A More Comprehensive Approach to the Neuroprotective Potential of Long-Chain Polyunsaturated Fatty Acids in Preterm Infants Is Needed-Should We Consider Maternal Diet and the n-6:n-3 Fatty Acid Ratio?

There is growing evidence that long-chain polyunsaturated fatty acids (LCPUFAs) are of importance for normal brain development. Adequate supply of LCPUFAs may be particularly important for preterm infants, because the third trimester is an important period of brain growth and accumulation of arachidonic acid (n-6 LCPUFA) and docosahexaenoic acid (n-3 LCPUFA). Fatty acids from the n-6 and n-3 series, particularly, have important functions in the brain as well as in the immune system, and their absolute and relative intakes may alter both the risk of impaired neurodevelopment and response to injury. This narrative review focuses on the potential importance of the n-6:n-3 fatty acid ratio in preterm brain development. Randomized trials of post-natal LCPUFA supplementation in preterm infants are presented. Pre-clinical evidence, results from observational studies in preterm infants as well as studies in term infants and evidence related to maternal diet during pregnancy, focusing on the n-6:n-3 fatty acid ratio, are also summarized. Two randomized trials in preterm infants have compared different ratios of arachidonic acid and docosahexaenoic acid intakes. Most of the other studies in preterm infants have compared formula supplemented with arachidonic acid and docosahexaenoic acid to un-supplemented formula. No trial has had a comprehensive approach to differences in total intake of both n-6 and n-3 fatty acids during a longer period of neurodevelopment. The results from preclinical and clinical studies indicate that intake of LCPUFAs during pregnancy and post-natal development is of importance for neurodevelopment and neuroprotection in preterm infants, but the interplay between fatty acids and their metabolites is complex. The best clinical approach to LCPUFA supplementation and n-6 to n-3 fatty acid ratio is still far from evident, and requires in-depth future studies that investigate specific fatty acid supplementation in the context of other fatty acids in the diet.

Omega-3 fatty acids and docosahexaenoic acid oxymetabolites modulate the inflammatory response of equine recombinant interleukin1β-stimulated equine synoviocytes

Omega-3 fatty acid (n-3 PUFA) supplementation may have beneficial effects in certain chronic diseases, potentially including osteoarthritis. Favorable effects are attributed, in part, to downstream pro-resolving oxylipid metabolites. We investigated the role of n-3 PUFA and docosahexaenoic acid (DHA)-derived oxylipids (docosanoids) on equine synoviocyte metabolism. We hypothesized that n-3 PUFA and selected docosanoids would modulate inflammatory mediator gene expression by recombinant equine (re)IL-1β-stimulated synovial fibroblasts. Synoviocyte monolayer cultures were prepared from grossly normal equine carpal synovium. Cellular incorporation of eicosapentaenoic acid (EPA) and DHA was determined using LC-MS and docosanoid biosynthesis by LC-MS-MS. The influence of n-3 PUFA and docosanoids on osteoarthritis marker gene expression was determined by quantitative real time polymerase chain reaction (qPCR). Synoviocytes incorporated EPA and DHA in significant amounts and DHA treatment augmented the synthesis of several docosanoids. Synoviocyte cultures pre-treated with EPA or DHA followed by reIL-1β stimulation had significant reductions in expression of ADAMTS4, MMP-1, MMP-13, IL-1β, IL-6 and COX-2. The docosanoids resolvin D1 and D2, maresin 1 and protectin DX, alone and in combination, abrogated ADAMTS4, MMP-1, MMP-13, and IL-6 gene expression in reIL-1β-stimulated synoviocytes. Similarly, both resolvins and maresin 1 stifled COX-2 expression. Our results demonstrate that synoviocytes readily incorporate n-3 PUFA. DHA incorporation was sufficient for biosynthesis of significant concentrations of several docosanoids which modulated the synovial inflammatory response in vitro. These data indicate n-3 PUFA supplementation may prove useful in the prevention or treatment of osteoarthritis.

Next-Generation Sequencing Identifies Polyunsaturated Fatty Acid Responsive Genes in the Juvenile Rat Cerebellum

Dietary n-3 polyunsaturated fatty acids (PUFA) influence postnatal brain growth and development. However, little data exist regarding the impacts of dietary n-3 PUFA in juvenile animals post weaning, which is a time of rapid growth. We tested the hypothesis that depleting dietary n-3 PUFA would result in modifications to the cerebellar transcriptome of juvenile rats. To test this hypothesis, three week old male rats (an age that roughly corresponds to an 11 month old child in brain development) were fed diets containing either soybean oil (SO) providing 1.1% energy from α-linolenic acid (ALA; 18:3n-3; ALA-sufficient) or corn oil (CO) providing 0.13% energy from ALA (ALA-deficient) for four weeks. Fatty acids (FAs) in the cerebellum were analyzed and revealed a 4-fold increase in n-6 docosapentaenoic acid (DPA; 22:5n-6), increases in arachidonic acid (AA; 20:4n-6) and docosatetraenoic acid (DTA; 22:4n-6), but no decrease in docosahexaenoic acid (DHA; 22:6n-3), in animals fed CO versus SO. Transcript abundance was then characterized to identify differentially expressed genes (DEGs) between the two diets. Upper quartile (UQ) scaling and transcripts per million (TPM) data normalization identified 100 and 107 DEGs, respectively. Comparison of DEGs from the two normalization methods identified 70 genes that overlapped, with 90% having abundance differences less than 2-fold. Nr4a3, a transcriptional activator that plays roles in neuroprotection and learning, was elevated over 2-fold from the CO diet. These data indicate that expression of Nr4a3 in the juvenile rat cerebellum is responsive to dietary n-3 PUFA, but additional studies are needed clarify the neurodevelopmental relationships between n-3 PUFA and Nr4a3 and the resulting impacts.

Dietary fatty acid composition impacts plasma fatty acid ethanolamide levels and body composition in golden Syrian hamsters

Fatty acid ethanolamides (FAEs) are a class of lipid amides that regulate numerous pathophysiological functions.

Does human ejaculate quality relate to phenotypic traits?

A given man's phenotype embodies cues of his ancestral ability to effectively defend himself and his kin from harm, to survive adverse conditions, and to acquire status and mating opportunities. In this review, we explore the hypothesis that a man's phenotype also embodies cues to fertility or the probability that an ejaculate will fertilize ova. Female mate choice depends on the ability to discern the quality of a male reproductive partner through his phenotype, and male fertility may be among the traits that females have evolved to detect. A female who selects as mates males that deliver higher quality ejaculates will, on average, be more fecund than her competitors. Data on several non-human species demonstrate correlations between ejaculate quality and secondary sexual characteristics that inform female mate choice, suggesting that females may select mates in part on the basis of fertility. While the non-human literature on this topic has advanced, the human literature remains limited in scope and there is no clear consensus on appropriate methodologies or theoretical positions. We provide a comprehensive review and meta-analysis of this literature, and conclude by proposing solutions to the many issues that impede progress in the field. In the process, we hope to encourage interest and insight from investigators in other areas of human mating and reproductive biology. Am. J. Hum. Biol. 28:318-329, 2016. © 2015 Wiley Periodicals, Inc.

A review on mitochondrial restorative mechanism of antioxidants in Alzheimer's disease and other neurological conditions

Neurodegenerative diseases are intricate in nature because of the involvement of the multiple pathophysiological events including mitochondrial dysfunction, neuroinflammation and oxidative stress. Alzheimer’s disease (AD) is a neurodegenerative disease explained by extracellular amyloid β deposits, intracellular neurofibrillary tangles and mitochondrial dysfunction. Increasing evidence has indicated that mitochondrial dysfunction displays significant role in the pathophysiological processes of AD. Mitochondrial dysfunction involves alterations in mitochondrial respiratory enzyme complex activities, oxidative stress, opening of permeability transition pore, and enhanced apoptosis. Various bioenergetics and antioxidants have been tried or under different investigational phase against AD and other neurodegenerative disorders (Parkinson’s disease, Huntington’s disease, and Amyotrophic lateral sclerosis) because of their complex and multiple site of action. These mitochondrial-targeting bioenergetics and antioxidant compounds such as coenzyme Q10, idebenone, creatine, mitoQ, mitovitE, MitoTEMPOL, latrepirdine, methylene blue, triterpenoids, SS peptides, curcumin, Ginkgo biloba, and omega-3 polyunsaturated fatty acids with potential efficacy in AD have been identified. Present review is intent to discuss mitochondrial restorative mechanisms of these bioenergetics and antioxidants as a potential alternative drug strategy for effective management of AD.

Omega-3 Fatty Acids in Early Prevention of Inflammatory Neurodegenerative Disease: A Focus on Alzheimer's Disease

Alzheimer's disease (AD) is the leading cause of dementia and the most common neurodegenerative disease in the elderly. Furthermore, AD has provided the most positive indication to support the fact that inflammation contributes to neurodegenerative disease. The exact etiology of AD is unknown, but environmental and genetic factors are thought to contribute, such as advancing age, family history, presence of chronic diseases such as cardiovascular disease (CVD) and diabetes, and poor diet and lifestyle. It is hypothesised that early prevention or management of inflammation could delay the onset or reduce the symptoms of AD. Normal physiological changes to the brain with ageing include depletion of long chain omega-3 fatty acids and brains of AD patients have lower docosahexaenoic acid (DHA) levels. DHA supplementation can reduce markers of inflammation. This review specifically focusses on the evidence in humans from epidemiological, dietary intervention, and supplementation studies, which supports the role of long chain omega-3 fatty acids in the prevention or delay of cognitive decline in AD in its early stages. Longer term trials with long chain omega-3 supplementation in early stage AD are warranted. We also highlight the importance of overall quality and composition of the diet to protect against AD and dementia.

Dietary factors in the etiology of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder. The majority of cases do not arise from purely genetic factors, implicating an important role of environmental factors in disease pathogenesis. Well-established environmental toxins important in PD include pesticides, herbicides, and heavy metals. However, many toxicants linked to PD and used in animal models are rarely encountered. In this context, other factors such as dietary components may represent daily exposures and have gained attention as disease modifiers. Several in vitro, in vivo, and human epidemiological studies have found a variety of dietary factors that modify PD risk. Here, we critically review findings on association between dietary factors, including vitamins, flavonoids, calorie intake, caffeine, alcohol, and metals consumed via food and fatty acids and PD. We have also discussed key data on heterocyclic amines that are produced in high-temperature cooked meat, which is a new emerging field in the assessment of dietary factors in neurological diseases. While more research is clearly needed, significant evidence exists that specific dietary factors can modify PD risk.

Omega-3 fatty acids in neurodegenerative diseases: focus on mitochondria

Mitochondrial dysfunction represents a common early pathological event in brain aging and in neurodegenerative diseases, e.g., in Alzheimer's (AD), Parkinson's (PD), and Huntington's disease (HD), as well as in ischemic stroke. In vivo and ex vivo experiments using animal models of aging and AD, PD, and HD mainly showed improvement of mitochondrial function after treatment with polyunsaturated fatty acids (PUFA) such as docosahexaenoic acid (DHA). Thereby, PUFA are particular beneficial in animals treated with mitochondria targeting toxins. However, DHA showed adverse effects in a transgenic PD mouse model and it is not clear if a diet high or low in PUFA might provide neuroprotective effects in PD. Post-treatment with PUFA revealed conflicting results in ischemic animal models, but intravenous administered DHA provided neuroprotective efficacy after acute occlusion of the middle cerebral artery. In summary, the majority of preclinical data indicate beneficial effects of n-3 PUFA in neurodegenerative diseases, whereas most controlled clinical trials did not meet the expectations. Because of the high half-life of DHA in the human brain clinical studies may have to be initiated much earlier and have to last much longer to be more efficacious.

Improved spatial learning and memory by perilla diet is correlated with immunoreactivities to neurofilament and α-synuclein in hilus of dentate gyrus

BACKGROUND

Perilla (Perilla frutescens) oil is very rich in α-linolenic acid, an omega-3 fatty acid. As it is widely reported that omega-3 fatty acid supplementation improves cognitive function in children and adults, feeding rats with perilla diets followed by analysis of proteomic changes in the hippocampus can provide valuable information on the mechanism of learning and memory at the molecular level. To identify proteins playing roles in learning and memory, differentially expressed proteins in the hippocampus of the 5 week old rats fed perilla diets for 3 weeks or 3 months were identified by proteomic analysis and validated by immunological assays.

RESULTS

The perilla diet groups showed improved spatial learning and memory performances in a T-maze test. They also displayed elevated level of 22:6n-3 fatty acid, an omega-3 fatty acid (p<0.05), in the brain compared to the control diet group. Quantitative proteomic analysis using 2-D gels as well as functional annotation grouping with the differentially expressed proteins in the hippocampus showed that those proteins involved in cytoskeleton and transport were the major differentially expressed proteins in the 3-week group, whereas those involved in energy metabolism, neuron projection and apoptosis in addition to cytoskeleton and transport were the major ones in the 3 month group. Differential protein expression in the hippocampus was validated by Western blotting using four selected proteins, known to be involved in synaptic plasticity; AMPA receptor, neurofilament, α-synuclein, and β-soluble NSF attachment protein. Brain sections from the perilla-diet groups showed enhanced immunoreactivities to α-synuclein and neurofilament. Especially, neurofilament immunoreactive cells manifested longer neurite projections in the hilus of dentate gyrus of the perilla-diet groups.

CONCLUSION

Improved cognitive function upon administration of n-3 fatty acid-rich perilla diet is associated with the differential expression of hippocampal proteins related to cytoskeleton, energy metabolism, transport, neuro-projection, and apoptosis. Particularly, the enhanced immunoreactivities to α-synuclein and neurofilament in the hilus of dentate gyrus suggest that perilla diet supplementation promotes neuronal signaling and alters synaptic plasticity for improved learning and memory.

Effects of supplementation with n-3 polyunsaturated fatty acids on cognitive performance and cardiometabolic risk markers in healthy 51 to 72 years old subjects: a randomized controlled cross-over study

Background

Higher plasma n-3 polyunsaturated fatty acids (PUFA) have been associated with a lower risk of age related cognitive decline, and to beneficially affect cardiometabolic risk factors. A relation exists between metabolic disorders such as diabetes type 2 and cognitive decline. Results regarding the potential effects of n-3 PUFA on risk factors in healthy subjects are divergent, and studies regarding the possible relation between cardiometabolic parameters and cognitive performance are scarce. The objective was to evaluate the effects of five weeks intake of long chain n-3 PUFA on cognitive performance in healthy individuals, and to exploit the possible relation between outcomes in cognitive tests to cardiometabolic risk parameters.

Methods

Fish oil n-3 PUFA (3g daily) were consumed during 5weeks separated by a 5 week washout period in a cross-over placebo controlled study, including 40 healthy middle aged to elderly subjects. Cognitive performance was determined by tests measuring working memory (WM) and selective attention.

Results

Supplementation with n-3 PUFA resulted in better performance in the WM-test compared with placebo (p < 0.05). In contrast to placebo, n-3 PUFA lowered plasma triacylglycerides (P < 0.05) and systolic blood pressure (p < 0.0001). Systolic blood pressure (p < 0.05), f-glucose (p = 0.05), and s-TNF-α (p = 0.05), were inversely related to the performance in cognitive tests.

Conclusions

Intake of n-3 PUFA improved cognitive performance in healthy subjects after five weeks compared with placebo. In addition, inverse relations were obtained between cardiometabolic risk factors and cognitive performance, indicating a potential of dietary prevention strategies to delay onset of metabolic disorders and associated cognitive decline.

n-3 PUFA status affects expression of genes involved in neuroenergetics differently in the fronto-parietal cortex compared to the CA1 area of the hippocampus: effect of rest and neuronal activation in the rat

n-3 Polyunsaturated fatty acids (PUFA) support whole brain energy metabolism but their impact on neuroenergetics in specific brain areas and during neuronal activation is still poorly understood. We tested the effect of feeding rats as control, n-3 PUFA-deficient diet, or docosahexaenoic acid (DHA)-supplemented diet on the expression of key genes in fronto-parietal cortex and hippocampal neuroenergetics before and after neuronal stimulation (activated) by an enriched environment. Compared to control rats, n-3 deficiency specifically repressed GLUT1 gene expression in the fronto-parietal cortex in basal state and also during neuronal activation which specifically stimulated GLUT1. In contrast, in the CA1 area, n-3 deficiency improved the glutamatergic synapse function in both neuronal states (glutamate transporters, Na(+)/K(+) ATPase). DHA supplementation induced overexpression of genes encoding enzymes of the oxidative phosphorylation system and the F1F0 ATP synthase in the CA1 area. We conclude that n-3 deficiency repressed GLUT1 gene expression in the cerebral cortex, while DHA supplementation improved the mitochondrial ATP generation in the CA1 area of the hippocampus.

The role of docosahexaenoic and the marine food web as determinants of evolution and hominid brain development: the challenge for human sustainability

Life originated on this planet about 3 billion years ago. For the first 2.5 billion years of life there was ample opportunity for DNA modification. Yet there is no evidence of significant change in life forms during that time. It was not until about 600 million years ago, when the oxygen tension rose to a point where air-breathing life forms became thermodynamically possible, that a major change can be abruptly seen in the fossil record. The sudden appearance of the 32 phyla in the Cambrian fossil record was also associated with the appearance of intracellular detail not seen in previous life forms. That detail was provided by cell membranes made with lipids (membrane fats) as structural essentials. Lipids thus played a major, as yet unrecognised, role as determinants in evolution. The compartmentalisation of intracellular, specialist functions as in the nucleus, mitochondria, reticulo-endothelial system and plasma membrane led to cellular specialisation and then speciation. Thus, not only oxygen but also the marine lipids were drivers in the Cambrian explosion. Docosahexaenoic acid (DHA) (all-cis-docosa-4,7,10,13,16,19-hexaenoic acid, C22:6ω3 or C22:6, n-3, DHA) is a major feature of marine lipids. It requires six oxygen atoms to insert its six double bonds, so it would not have been abundant before oxidative metabolism became plentiful. DHA provided the membrane backbone for the emergence of new photoreceptors that converted photons into electricity, laying the foundation for the evolution of other signalling systems, the nervous system and the brain. Hence, the ω3 DHA from the marine food web must have played a critical role in human evolution. There is also clear evidence from molecular biology that DHA is a determinant of neuronal migration, neurogenesis and the expression of several genes involved in brain growth and function. That same process was essential to the ultimate cerebral expansion in human evolution. There is now incontrovertible support of this hypothesis from fossil evidence of human evolution taking advantage of the marine food web. Lipids are still modifying the present evolutionary phase of our species; their signature is evident in the changing panorama of non-communicable diseases. The most worrying change in disease pattern is the sharp rise in brain disorders, which, in the European Union, has overtaken the cost of all other burdens of ill health at €386 billion for the 25 member states at 2004 prices. In 2007, the UK cost was estimated at £77 billion and confirmed in 2010 at £105 billion - greater than heart disease and cancer combined. The rise in mental ill health is now being globalised. The solution to the rising vascular disorders in the last century and now brain disorders in this century lies in a radical reappraisal of the food system, which last century was focussed on protein and calories, with little attention paid to the requirements of the brain - the very organ that was the determinant of human evolution. With the marine fish catch having plateaued 20 years ago and its sustainability now under threat, a critical aspect of this revision is the development of marine agriculture from estuarine, coastal and oceanic resources. Such action is likely to play a key role in future health and intelligence.

Α-synuclein neuropathology is controlled by nuclear hormone receptors and enhanced by docosahexaenoic acid in a mouse model for Parkinson's disease

α-Synuclein (α-Syn) is a neuronal protein that accumulates progressively in Parkinson's disease (PD) and related synucleinopathies. Attempting to identify cellular factors that affect α-Syn neuropathology, we previously reported that polyunsaturated fatty acids (PUFAs) promote α-Syn oligomerization and aggregation in cultured cells. We now report that docosahexaenoic acid (DHA), a 22:6 PUFA, affects α-Syn oligomerization by activating retinoic X receptor (RXR) and peroxisome proliferator-activated receptor γ2 (PPARγ2). In addition, we show that dietary changes in brain DHA levels affect α-Syn cytopathology in mice transgenic for the PD-causing A53T mutation in human α-Syn. A diet enriched in DHA, an activating ligand of RXR, increased the accumulation of soluble and insoluble neuronal α-Syn, neuritic injury and astrocytosis. Conversely, abnormal accumulations of α-Syn and its deleterious effects were significantly attenuated by low dietary DHA levels. Our results suggest a role for activated RXR/PPARγ 2, obtained by elevated brain PUFA levels, in α-Syn neuropathology.

Human and great ape red blood cells differ in plasmalogen levels and composition

Background

Plasmalogens are ether phospholipids required for normal mammalian developmental, physiological, and cognitive functions. They have been proposed to act as membrane antioxidants and reservoirs of polyunsaturated fatty acids as well as influence intracellular signaling and membrane dynamics. Plasmalogens are particularly enriched in cells and tissues of the human nervous, immune, and cardiovascular systems. Humans with severely reduced plasmalogen levels have reduced life spans, abnormal neurological development, skeletal dysplasia, impaired respiration, and cataracts. Plasmalogen deficiency is also found in the brain tissue of individuals with Alzheimer disease.

Results

In a human and great ape cohort, we measured the red blood cell (RBC) levels of the most abundant types of plasmalogens. Total RBC plasmalogen levels were lower in humans than bonobos, chimpanzees, and gorillas, but higher than orangutans. There were especially pronounced cross-species differences in the levels of plasmalogens with a C16:0 moiety at the sn-1 position. Humans on Western or vegan diets had comparable total RBC plasmalogen levels, but the latter group showed moderately higher levels of plasmalogens with a C18:1 moiety at the sn-1 position. We did not find robust sex-specific differences in human or chimpanzee RBC plasmalogen levels or composition. Furthermore, human and great ape skin fibroblasts showed only modest differences in peroxisomal plasmalogen biosynthetic activity. Human and chimpanzee microarray data indicated that genes involved in plasmalogen biosynthesis show cross-species differential expression in multiple tissues.

Conclusion

We propose that the observed differences in human and great ape RBC plasmalogens are primarily caused by their rates of biosynthesis and/or turnover. Gene expression data raise the possibility that other human and great ape cells and tissues differ in plasmalogen levels. Based on the phenotypes of humans and rodents with plasmalogen disorders, we propose that cross-species differences in tissue plasmalogen levels could influence organ functions and processes ranging from cognition to reproduction to aging.

The neurobiology of lipid metabolism in autism spectrum disorders

Autism is a neurodevelopmental disorder characterized by impairments in communication and reciprocal social interaction, coupled with repetitive behavior, which typically manifests by 3 years of age. Multiple genes and early exposure to environmental factors are the etiological determinants of the disorder that contribute to variable expression of autism-related traits. Increasing evidence indicates that altered fatty acid metabolic pathways may affect proper function of the nervous system and contribute to autism spectrum disorders. This review provides an overview of the reported abnormalities associated with the synthesis of membrane fatty acids in individuals with autism as a result of insufficient dietary supplementation or genetic defects. Moreover, we discuss deficits associated with the release of arachidonic acid from the membrane phospholipids and its subsequent metabolism to bioactive prostaglandins via phospholipase A(2)-cyclooxygenase biosynthetic pathway in autism spectrum disorders. The existing evidence for the involvement of lipid neurobiology in the pathology of neurodevelopmental disorders such as autism is compelling and opens up an interesting possibility for further investigation of this metabolic pathway.

Ácidos graxos poli-insaturados n-3 e n-6: metabolismo em mamíferos e resposta imune

A experimentação animal apresenta uma grande importância para o desenvolvimento da ciência. O uso de camundongos em experimentos ocorre devido à semelhança destes animais com os seres humanos, fácil criação e manutenção e resposta experimental bastante rápida. Esses animais possuem as mesmas enzimas dessaturases e elongases que os humanos, por isso são usados em pesquisas envolvendo incorporação e síntese de ácidos graxos em tecidos. Os ácidos graxos da família ômega-3 e ômega-6 são de suma importância na dieta humana, pois estes não são sintetizados pela síntese de novo e são precursores dos ácidos graxos poli-insaturados de cadeia muito longa, como os ácidos eicosapentaenóico, docosahexaenóico e araquidônico. Estes desempenham funções importantes no organismo, como a síntese de eicosanóides que estão envolvidos diretamente no sistema imune e nas respostas inflamatórias. A razão entre o consumo de ácidos graxos n-6 e n-3 na dieta é um importante fator para determinar a ingestão adequada de ácidos graxos bem como prevenir o aparecimento de doenças. Este artigo tem como objetivo avaliar a incorporação de ácidos graxos em tecidos de animais e discutir a importância dos ácidos da família n-3 e seus metabólitos no sistema imunológico.

Synergic effect of eicosapentaenoic acid and lovastatin on gene expression of HMGCoA reductase and LDL receptor in cultured HepG2 cells

Background

PUFAs are potent inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, an enzyme catalyzing the conversion of HMGCoA to mevalonate, the rate limiting step in cholesterol biosynthesis. Statins represent a class of drugs that are widely used to treat hypercholesterolemia for their ability to inhibit cholesterol biosynthesis and to up-regulate the synthesis of Low Density Lipoprotein (LDL) receptors in the liver. PUFAs mediate many, if not all, actions of statins and this could be one mechanism by which they lower cholesterol levels. The purpose of this study was to investigate whether combined treatment with Eicosapentaenoic acid (EPA) and lovastatin enhanced the regulatory effect on gene expression of HMGCoA reductase and LDL receptor in HepG2 cell line.

Results

The combined treatment with EPA and lovastatin enhanced the regulatory effect on gene expression of HMGCoA reductase and LDL receptor in HepG2 cell line. Moreover, we detected a synergistic effect on the inhibition of cancer cell proliferation obtained by combination of EPA and Lovastatin.

Conclusions

The use of EPA, in combination with low doses of Lovastatin may have potential value in treatment of neoplastic diseases.

Liposome-incorporated DHA increases neuronal survival by enhancing non-amyloidogenic APP processing

The fluidity of neuronal membranes plays a pivotal role in brain aging and neurodegeneration. In this study, we investigated the role of the omega-3 fatty acid docosahexaenoic acid (DHA) in modulation of membrane fluidity, APP processing, and protection from cytotoxic stress. To this end, we applied unilamellar transfer liposomes, which provided protection from oxidation and effective incorporation of DHA into cell membranes. Liposomes transferring docosanoic acid (DA), the completely saturated form of DHA, to the cell cultures served as controls. In HEK-APP cells, DHA significantly increased membrane fluidity and non-amyloidogenic processing of APP, leading to enhanced secretion of sAPPα. This enhanced secretion of sAPPα was associated with substantial protection against apoptosis induced by ER Ca(2+) store depletion. sAPPα-containing supernatants obtained from HEK-APP cells exerted similar protective effects as DHA in neuronal PC12 cells and HEK293 control cells. Correlating to further increased sAPPα levels, supernatants obtained from DHA-treated HEK-APP cells enhanced protection, whereas supernatants obtained from DHA-treated HEK293 control cells did not inhibit apoptosis, likely due to the low expression of endogenous APP and negligible sAPPα secretion in these cells. Further experiments with the small molecule inhibitors LY294002 and SP600125 indicated that sAPPα-induced cytoprotection relied on activation of the anti-apoptotic PI3K/Akt pathway and inhibition of the stress-triggered JNK signaling pathway in PC12 cells. Our data suggest that liposomal DHA is able to restore or maintain physiological membrane properties, which are required for neuroprotective sAPPα secretion and autocrine modulation of neuronal survival.

Why is intelligence correlated with semen quality?: Biochemical pathways common to sperm and neuron function and their vulnerability to pleiotropic mutations

We recently found positive correlations between human general intelligence and three key indices of semen quality, and hypothesized that these correlations arise through a phenotype-wide 'general fitness factor' reflecting overall mutation load. In this addendum we consider some of the biochemical pathways that may act as targets for pleiotropic mutations that disrupt both neuron function and sperm function in parallel. We focus especially on the inter-related roles of polyunsaturated fatty acids, exocytosis and receptor signaling.

The nutritional and clinical significance of lipid rafts

PURPOSE OF REVIEW

Lipid rafts are potentially modifiable by diet, particularly (but not exclusively) by dietary fatty acids. This review examines the potential for dietary modification of raft structure and function in the immune system, brain and retinal tissue, the gut, and in cancer cells.

RECENT FINDINGS

In-vitro and ex-vivo studies suggest that dietary n-3 polyunsaturated fatty acids (PUFAs) may exert immunosuppressive and anticancer effects through changes in lipid raft organization. In addition, gangliosides and cholesterol may modulate lipid raft organization in a number of tissues, and recent work has highlighted sphingolipids in membrane microdomains as potential targets for inhibition of tumor growth. The roles of fatty acids and gangliosides, especially in relation to lipid rafts, in cognitive development, age-related cognitive decline, psychiatric disorders, and Alzheimer's disease are poorly understood and require further investigation. The roles of lipid rafts in cancer, in microbial pathogenesis, and in insulin resistance are starting to emerge, and indicate compelling evidence for the growing importance of membrane microdomains in health and disease.

SUMMARY

In-vitro and animal studies show that n-3 PUFAs, cholesterol, and gangliosides modulate the structure and composition of lipid rafts, potentially influencing a wide range of biological processes, including immune function, neuronal signaling, cancer cell growth, entry of pathogens through the gut barrier, and insulin resistance in metabolic disorders. The physiological, clinical, and nutritional relevance of these observations remains to be determined.

Individual phospholipid classes from iberian pig meat as affected by diet

The main objectives of this study were to (1) determine the individual phospholipid (PL) classes content of fresh meat from Iberian pigs and their respective fatty acid and dimethylacetal composition and (2) assess the effect of different diets (acorn and grass vs oleic acid enriched concentrates) on these lipid species. First, it was found that phosphatidylcholine was the major PL, followed by phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol in decreasing order. Each PL class showed a different lipid profile. Second, the feeding regimen influenced the quantity and the fatty composition of the individual PL classes. Meat from pigs fattened with high oleic acid concentrates had higher amounts of most phospholipid classes and polyunsaturated fatty acids, which is an indication of lipid oxidation instability. Lastly, these differences in PL species and fatty acid composition could be used to differentiate meats from Iberian pigs with different feeding regimens.

A high-fat diet induces lower expression of retinoid receptors and their target genes GAP-43/neuromodulin and RC3/neurogranin in the rat brain

Numerous studies have reported an association between cognitive impairment in old age and nutritional factors, including dietary fat. Retinoic acid (RA) plays a central role in the maintenance of cognitive processes via its nuclear receptors (NR), retinoic acid receptor (RAR) and retinoid X receptor (RXR), and the control of target genes, e.g. the synaptic plasticity markers GAP-43/neuromodulin and RC3/neurogranin. Given the relationship between RA and the fatty acid signalling pathways mediated by their respective NR (RAR/RXR and PPAR), we investigated the effect of a high-fat diet (HFD) on (1) PUFA status in the plasma and brain, and (2) the expression of RA and fatty acid NR (RARbeta, RXRbetagamma and PPARdelta), and synaptic plasticity genes (GAP-43 and RC3), in young male Wistar rats. In the striatum of rats given a HFD for 8 weeks, real-time PCR (RT-PCR) revealed a decrease in mRNA levels of RARbeta ( - 14 %) and PPARdelta ( - 13 %) along with an increase in RXRbetagamma (+52 %). Concomitantly, RT-PCR and Western blot analysis revealed (1) a clear reduction in striatal mRNA and protein levels of RC3 ( - 24 and - 26 %, respectively) and GAP-43 ( - 10 and - 42 %, respectively), which was confirmed by in situ hybridisation, and (2) decreased hippocampal RC3 and GAP-43 protein levels (approximately 25 %). Additionally, HFD rats exhibited a significant decrease in plasma ( - 59 %) and brain ( - 6 %) n-3 PUFA content, mainly due to the loss of DHA. These results suggest that dietary fat induces neurobiological alterations by modulating the brain RA signalling pathway and n-3 PUFA content, which have been previously correlated with cognitive impairment.

Amyloid-Beta Peptide, Oxidative Stress and Inflammation in Alzheimer's Disease: Potential Neuroprotective Effects of Omega-3 Polyunsaturated Fatty Acids

Alzheimer's disease is the most common form of dementia in the elderly and is a progressive neurodegenerative disorder characterised by a decline in cognitive function and also profound alterations in mood and behaviour. The pathology of the disease is characterised by the presence of extracellular amyloid peptide deposits and intracellular neurofibrillary tangles in the brain. Although many hypotheses have been put forward for the aetiology of the disease, increased inflammation and oxidative stress appear key to be features contributing to the pathology. The omega-3 polyunsaturated fats, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) have well-characterised effects on inflammation and may have neuroprotective effects in a number of neurodegenerative conditions including Alzheimer's disease. The aims of this paper are to review the neuroprotective effects of EPA and DHA in Alzheimer's disease, with special emphasis on their role in modulating oxidative stress and inflammation and also examine their potential as therapeutic agents.

Rat brain docosahexaenoic acid metabolism is not altered by a 6-day intracerebral ventricular infusion of bacterial lipopolysaccharide

In a rat model of neuroinflammation, produced by a 6-day intracerebral ventricular infusion of bacterial lipopolysaccharide (LPS), we reported that the brain concentrations of non-esterified brain arachidonic acid (AA, 20:4 n-6) and its eicosanoid products PGE(2) and PGD(2) were increased, as were AA turnover rates in certain brain phospholipids and the activity of AA-selective cytosolic phospholipase A(2) (cPLA(2)). The activity of Ca(2+)-independent iPLA(2), which is thought to be selective for the release of docosahexaenoic acid (DHA, 22:6 n-3) from membrane phospholipid, was unchanged. In the present study, we measured parameters of brain DHA metabolism in comparable artificial cerebrospinal fluid (control) and LPS-infused rats. In contrast to the reported changes in markers of AA metabolism, the brain non-esterified DHA concentration and DHA turnover rates in individual phospholipids were not significantly altered by LPS infusion. The formation rates of AA-CoA and DHA-CoA in a microsomal brain fraction were also unaltered by the LPS infusion. These observations indicate that LPS-treatment upregulates markers of brain AA but not DHA metabolism. All of which are consistent with other evidence that suggest different sets of enzymes regulate AA and DHA recycling within brain phospholipids and that only selective increases in brain AA metabolism occur following a 6-day LPS infusion.

Nutrition and Alzheimer's disease: pre-clinical concepts

Alzheimer's disease (AD) is a progressive condition characterized by neurodegeneration and the dense deposition of proteins in the brain. There is no cure for AD and current treatments usually only provide a temporary reduction of symptoms. There is thus a strong unmet need for effective preventative and therapeutic strategies and the potential role for nutrition in such strategies is rapidly gaining interest. An Alzheimer's brain contains fewer synapses and reduced levels of synaptic proteins and membrane phosphatides. Brain membrane phosphatide synthesis requires at least three dietary precursors: polyunsaturated fatty acids, uridine monophosphate (UMP) and choline. Animal studies have shown that administration of these nutrients increases the level of phosphatides, specific pre- or post-synaptic proteins and the number of dendritic spines - a requirement for new synapse formation. These effects are markedly enhanced when animals receive all three compounds together. This multi-nutrient approach in animals has also been shown to decrease amyloid beta protein (Abeta) plaque burden, improve learning and memory through increased cholinergic neurotransmission and have a neuroprotective effect in several mouse models of AD. Whether these potential therapeutic effects of a multi-nutrient approach observed in animal models can also be replicated in a clinical setting warrants further investigation.

Alpha-linolenic acid and its conversion to longer chain n-3 fatty acids: benefits for human health and a role in maintaining tissue n-3 fatty acid levels

There is little doubt regarding the essential nature of alpha-linolenic acid (ALA), yet the capacity of dietary ALA to maintain adequate tissue levels of long chain n-3 fatty acids remains quite controversial. This simple point remains highly debated despite evidence that removal of dietary ALA promotes n-3 fatty acid inadequacy, including that of docosahexaenoic acid (DHA), and that many experiments demonstrate that dietary inclusion of ALA raises n-3 tissue fatty acid content, including DHA. Herein we propose, based upon our previous work and that of others, that ALA is elongated and desaturated in a tissue-dependent manner. One important concept is to recognize that ALA, like many other fatty acids, rapidly undergoes beta-oxidation and that the carbons are conserved and reused for synthesis of other products including cholesterol and fatty acids. This process and the differences between utilization of dietary DHA or liver-derived DHA as compared to ALA have led to the dogma that ALA is not a useful fatty acid for maintaining tissue long chain n-3 fatty acids, including DHA. Herein, we propose that indeed dietary ALA is a crucial dietary source of n-3 fatty acids and its dietary inclusion is critical for maintaining tissue long chain n-3 levels.

Neurological benefits of omega-3 fatty acids

The central nervous system is highly enriched in long-chain polyunsaturated fatty acid (PUFA) of the omega-6 and omega-3 series. The presence of these fatty acids as structural components of neuronal membranes influences cellular function both directly, through effects on membrane properties, and also by acting as a precursor pool for lipid-derived messengers. An adequate intake of omega-3 PUFA is essential for optimal visual function and neural development. Furthermore, there is increasing evidence that increased intake of the long-chain omega-3 PUFA, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may confer benefits in a variety of psychiatric and neurological disorders, and in particular neurodegenerative conditions. However, the mechanisms underlying these beneficial effects are still poorly understood. Recent evidence also indicates that in addition to the positive effects seen in chronic neurodegenerative conditions, omega-3 PUFA may also have significant neuroprotective potential in acute neurological injury. Thus, these compounds offer an intriguing prospect as potentially new therapeutic approaches in both chronic and acute conditions. The purpose of this article is to review the current evidence of the neurological benefits of omega-3 PUFA, looking specifically at neurodegenerative conditions and acute neurological injury.

Expression of E-FABP in PC12 cells increases neurite extension during differentiation: involvement of n-3 and n-6 fatty acids

Epidermal fatty acid-binding protein (E-FABP), a member of the family of FABPs, exhibits a robust expression in neurons during axonal growth in development and in nerve regeneration following nerve injury. This study examines the impact of E-FABP expression in normal neurite extension in differentiating pheochromocytoma cell (PC12) cultures supplemented with selected long chain free fatty acids (LCFFA). We found that E-FABP binds to a broad range of saturated and unsaturated LCFFAs, including those with potential interest for neuronal differentiation and axonal growth such as C22:6n-3 docosahexaenoic acid (DHA), C20:5n-3 eicosapentaenoic acid (EPA), and C20:4n-6 arachidonic acid (ARA). PC12 cells exposed to nerve growth factor (NGFDPC12) exhibit high E-FABP expression that is blocked by mitogen-activated protein kinase kinase (MEK) inhibitor U0126. Nerve growth factor-differentiated pheochromocytoma cells (NGFDPC12) antisense clones (NGFDPC12-AS) which exhibit low E-FABP expression have fewer/shorter neurites than cells transfected with vector only or NGFDPC12 sense cells (NGFDPC12-S). Replenishing NGFDPC12-AS cells with biotinylated recombinant E-FABP (biotin-E-FABP) protein restores normal neurite outgrowth. Cellular localization of biotin-E-FABP in NGFDPC12 was detected mostly in the cytoplasm and in the nuclear region. Treatment of NGFDPC12 with DHA, EPA, or ARA further enhances neurite length but it does not trigger further induction of TrkA or MEK phosphorylation or E-FABP mRNA observed in differentiating PC12 cells without LCFFA supplementation. Significantly, DHA and EPA neurite stimulating effects are higher in NGFDPC12-S than in NGFDPC12-AS cells. These findings are consistent with the scenario that neurite extension of differentiating PC12 cells, including further stimulation by DHA and EPA, requires sufficient cellular levels of E-FABP.

Polyunsaturated fatty acids induce alpha-synuclein-related pathogenic changes in neuronal cells

The misfolding and aggregation of normally soluble proteins has emerged as a key feature of several neurodegenerative diseases. In Parkinson's disease, progressive loss of dopaminergic neurons is accompanied by polymerization of the cytoplasmic protein alpha-synuclein (alphaS) into filamentous inclusions found in neuronal somata (Lewy bodies) and dendrites (Lewy neurites). Similar alphaS aggregates occur in cortical neurons in dementia with Lewy bodies. Numerous reports now indicate that alphaS can interact with lipids. We previously found that treating dopaminergic cells expressing alphaS with polyunsaturated fatty acids (PUFAs) induced the formation of soluble, sodium dodecyl sulfate-stable oligomers whereas treatment with saturated fatty acids did not. Here, we examine the relevance of alphaS-PUFA interactions to the development of Parkinson's disease-like cytopathology. Exposure of alphaS-overexpressing dopaminergic or neuronal cell lines to physiological levels of a PUFA induced the formation of proteinaceous inclusions in the cytoplasm. Kinetic experiments indicated that PUFA-induced soluble oligomers of alphaS precede these Lewy-like inclusions. Importantly, we found that alphaS oligomers were associated with cyto-toxicity, whereas the development of Lewy-like inclusions appeared to be protective. We conclude that alterations in PUFA levels can lead to aggregation of alphaS and subsequent deposition into potentially cyto-toxic oligomers that precede inclusions in dopaminergic cells.

Phospholipases and fatty acid signalling in exocytosis

Vesicle fusion is a ubiquitous biological process involved in general membrane trafficking and a variety of specialized events, for example release of neurotransmitters and hormones, sperm acrosome exocytosis, plasma membrane repair and neurite outgrowth. Many vesicle fusion events have long been known to be activated by phospholipases and products of their activity, such as polyunsaturated arachidonic acid. Polyunsaturated fatty acids (PUFAs) have been proposed to have a number of multiple effectors, including ion channels and the cytoskeleton, but the precise mechanism of PUFA action is still unclear. It was recently reported that omega-3 and omega-6 PUFAs can act on syntaxin, a plasma membrane protein directly involved in vesicle fusion. In this review, we will discuss the role of this new mode of PUFA action in exocytosis.

The roles of NADPH oxidase and phospholipases A2 in oxidative and inflammatory responses in neurodegenerative diseases

Reactive oxygen species (ROS) are produced in mammalian cells through enzymic and non-enzymic mechanisms. Although some ROS production pathways are needed for specific physiological functions, excessive production is detrimental and is regarded as the basis of numerous neurodegenerative diseases. Among enzymes producing superoxide anions, NADPH oxidase is widespread in mammalian cells and is an important source of ROS in mediating physiological and pathological processes in the cardiovascular and the CNS. ROS production is linked to the alteration of intracellular calcium homeostasis, activation of Ca(2+)-dependent enzymes, alteration of cytoskeletal proteins, and degradation of membrane glycerophospholipids. There is evolving evidence that ROS produced by NADPH oxidase regulate neuronal functions and degrade membrane phospholipids through activation of phospholipases A(2) (PLA(2)). This review is intended to cover recent studies describing ROS generation from NADPH oxidase in the CNS and its downstream activation of PLA(2), namely, the group IV cytosolic cPLA(2) and the group II secretory sPLA(2). A major focus is to elaborate the dual role of NADPH oxidase and PLA(2) in mediating the oxidative and inflammatory responses in neurodegenerative diseases, including cerebral ischemia and Alzheimer's disease. Elucidation of the signaling pathways linking NADPH oxidase with the multiple forms of PLA(2) will be important in understanding the oxidative and degradative mechanisms that underline neuronal damage and glial activation and will facilitate development of therapeutic intervention for prevention and treatment of these and other neurodegenerative diseases.

Modulation of inflammation in brain: a matter of fat

Neuroinflammation is a host defense mechanism associated with neutralization of an insult and restoration of normal structure and function of brain. Neuroinflammation is a hallmark of all major CNS diseases. The main mediators of neuroinflammation are microglial cells. These cells are activated during a CNS injury. Microglial cells initiate a rapid response that involves cell migration, proliferation, release of cytokines/chemokines and trophic and/or toxic effects. Cytokines/chemokines stimulate phospholipases A2 and cyclooxygenases. This results in breakdown of membrane glycerophospholipids with the release of arachidonic acid (AA) and docosahexaenoic acid (DHA). Oxidation of AA produces pro-inflammatory prostaglandins, leukotrienes, and thromboxanes. One of the lyso-glycerophospholipids, the other products of reactions catalyzed by phospholipase A2, is used for the synthesis of pro-inflammatory platelet-activating factor. These pro-inflammatory mediators intensify neuroinflammation. Lipoxin, an oxidized product of AA through 5-lipoxygenase, is involved in the resolution of inflammation and is anti-inflammatory. Docosahexaenoic acid is metabolized to resolvins and neuroprotectins. These lipid mediators inhibit the generation of prostaglandins, leukotrienes, and thromboxanes. Levels of prostaglandins, leukotrienes, and thromboxanes are markedly increased in acute neural trauma and neurodegenerative diseases. Docosahexaenoic acid and its lipid mediators prevent neuroinflammation by inhibiting transcription factor NFkappaB, preventing cytokine secretion, blocking the synthesis of prostaglandins, leukotrienes, and thromboxanes, and modulating leukocyte trafficking. Depending on its timing and magnitude in brain tissue, inflammation serves multiple purposes. It is involved in the protection of uninjured neurons and removal of degenerating neuronal debris and also in assisting repair and recovery processes. The dietary ratio of AA to DHA may affect neurodegeneration associated with acute neural trauma and neurodegenerative diseases. The dietary intake of docosahexaenoic acid offers the possibility of counter-balancing the harmful effects of high levels of AA-derived pro-inflammatory lipid mediators.

Fish oil and mental health: the role of n-3 long-chain polyunsaturated fatty acids in cognitive development and neurological disorders

Epidemiological and experimental studies have indicated that consumption of more n-3 long-chain polyunsaturated fatty acids may reduce the risk for a variety of diseases, including cardiovascular, neurological and immunological disorders, diabetes and cancer. This article focuses on the role of marine n-3 long-chain polyunsaturated fatty acids in brain functions, including the development of the central nervous system and neurological disorders. An overview of the major animal studies and clinical trials is provided here, focusing on fatty acid supplementation during pregnancy and infancy, and prevention and management of Alzheimer's disease, schizophrenia, depression and attention deficit hyperactive disorder. Although an optimal balance in n-3/n-6 long-chain polyunsaturated fatty acid ratio is important for proper neurodevelopment and cognitive functions, results from randomized controlled trials are controversial and do not confirm any useful effect of supplementation on development of preterm and term infants. The relationship between fatty acid status and mental disorders is confirmed by reduced levels of n-3 long-chain polyunsaturated fatty acids in erythrocyte membranes of patients with central nervous system disorders. Nevertheless, there are very little data supporting the use of fish oil in those patients. The only way to verify whether n-3 long-chain polyunsaturated fatty acids are a potential therapeutic option in the management and prevention of mental disorders is to conduct a large definitive randomized controlled trials similar to those required for the licensing of any new pharmacological treatment.

Omega-3 fatty acid deficiency in major depressive disorder is caused by the interaction between diet and a genetically determined abnormality in phospholipid metabolism

Omega-3 fatty acids are a type of polyunsaturated fatty acid (PUFA). A growing body of evidence suggests that this form PUFA is a useful and well tolerated treatment for major depressive disorder, a common and serious mental illness. The efficacy of omega-3 PUFA is routinely explained as being due to a deficiency caused by inadequate dietary intake of this class of fatty acid. The hypothesis considered states that low omega-3 PUFA abundance in patients with major depressive and related disorders is due to an underlying genetically determined abnormality. The hypothesis can explain why although a specific and consistent deficit in omega-3, but not omega-6, PUFA occurs in major depressive and related disorders, the literature does not consistently support the notion that this is due to deficient dietary intake. Specifically it is hypothesized that having genetically determined low activity of fatty acid CoA ligase 4 and/or Type IV phospholipase A(2) combined with the low dietary availability of omega-3 PUFA results in reduced cellular uptake of omega-3 PUFA and constitutes a risk factor for depression. The hypothesis also has important consequences for the pharmacological treatment of depression in that it predicts that administering agents which enhance phospholipid synthesis, particularly those containing ethanolamine such as CDP-ethanolamine, should be effective antidepressants especially when co-administered with omega-3 PUFA.

G protein-coupled receptor systems and their lipid environment in health disorders during aging

Cells, tissues and organs undergo phenotypic changes and deteriorate as they age. Cell growth arrest and hyporesponsiveness to extrinsic stimuli are all hallmarks of senescent cells. Most such external stimuli received by a cell are processed by two different cell membrane systems: receptor tyrosine kinases (RTKs) and G protein-coupled receptors (GPCRs). GPCRs form the largest gene family in the human genome and they are involved in most relevant physiological functions. Given the changes observed in the expression and activity of GPCRs during aging, it is possible that these receptors are directly involved in aging and certain age-related pathologies. On the other hand, both GPCRs and G proteins are associated with the plasma membrane and since lipid-protein interactions regulate their activity, they can both be considered to be sensitive to the lipid environment. Changes in membrane lipid composition and structure have been described in aged cells and furthermore, these membrane changes have been associated with alterations in GPCR mediated signaling in some of the main health disorders in elderly subjects. Although senescence could be considered a physiologic process, not all aging humans develop the same health disorders. Here, we review the involvement of GPCRs and their lipid environment in the development of the major human pathologies associated with aging such as cancer, neurodegenerative disorders and cardiovascular pathologies.

Unique molecular signatures of glycerophospholipid species in different rat tissues analyzed by tandem mass spectrometry

Glycerophospholipids (GPL) in animal tissues are composed of a large array of molecular species that mainly differ in the fatty acyl composition. In order to further understand the roles of GPL at the molecular level, it is necessary to have comprehensive, accurate accounts of the molecular makeup for these molecules in animal tissues. However, this task was difficult simply because the conventional technologies of profiling GPL species depended heavily on technical skill for accuracy and reliability and were extremely labor-intensive. In recent years, tandem mass spectrometry (MS/MS) proved to be a highly reliable and sensitive technology for profiling small molecules, including GPL, in biological samples. In this study, we used this technology to perform simultaneous comparative analyses for phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS) and phosphatidylinositol (PI) in the same lipid preparations of liver, lung, kidney, heart, pancreas, stomach, small intestine, spleen, skeleton muscle and brain of an adult rat. We produced molecular profiles of these 4 GPL classes in these 10 different tissues that are highly reproducible between different scans of the same sample and between samples from different animals. It is intriguing that each tissue was found to possess a unique signature of GPL profile that may be used to identify unknown tissues. More importantly, these profiles may also set reference points for studying changes of GPL metabolism in different physiological and pathological conditions.

Nutrigenomics: integrating genomic approaches into nutrition research

It has been suggested that the supermarket of today will be the pharmacy of tomorrow. Such statements have been derived from recognition of our increasing ability to optimize nutrition, and maintain a state of good health through longer periods of life. The new field of nutrigenomics, which focuses on the interaction between bioactive dietary components and the genome, recognizes that current nutritional guidelines may be ideal for only a relatively small proportion of the population. There is good evidence that nutrition has significant influences on the expression of genes, and, likewise, genetic variation can have a significant effect on food intake, metabolic response to food, individual nutrient requirements, food safety, and the efficacy of disease-protective dietary factors. For example, a significant number of human studies in various areas are increasing the evidence for interactions between single nucleotide polymorphisms (SNPs) in various genes and the metabolic response to diet, including the risk of obesity. Many of the same genetic polymorphisms and dietary patterns that influence obesity or cardiovascular disease also affect cancer, since overweight individuals are at increased risk of cancer development. The control of food intake is profoundly affected by polymorphisms either in genes encoding taste receptors or in genes encoding a number of peripheral signaling peptides such as insulin, leptin, ghrelin, cholecystokinin, and corresponding receptors. Total dietary intake, and the satiety value of various foods, will profoundly influence the effects of these genes. Identifying key SNPs that are likely to influence the health of an individual provides an approach to understanding and, ultimately, to optimizing nutrition at the population or individual level. Traditional methods for identification of SNPs may involve consideration of individual variants, using methodologies such as restriction fragment length polymorphisms or quantitative real-time PCR assays. New developments allow identification of up to 500,000 SNPs in an individual, and with increasingly lowered pricings these developments may explode the population-level potential for dietary optimization based on nutrigenomic approaches.