The role of n-3 polyunsaturated fatty acids in brain: modulation of rat brain gene expression by dietary n-3 fatty acids

Omega-3 fatty acids and monoamine neurotransmission

We proposed several years ago that the behavioral effects of n-3 PUFA deficiency observed in animal models might be mediated through the dopaminergic and serotonergic systems that are very involved in the modulation of attention, motivation and emotion. We evaluated this hypothesis in an extended series of experiments on rats chronically diet-deficient in alpha-linolenic acid, the precursor of long-chain n-3 PUFA, in which we studied several parameters of these neurotransmission systems. The present paper synthesizes the main data we obtained on interactions between n-3 PUFA status and neurotransmission in animal models. We demonstrated that several parameters of neurotransmission were affected, such as the vesicular pool of dopamine and serotonin, thus inducing several regulatory processes such as modification of cerebral receptors in specific brain areas. We also demonstrated that (i) a reversal diet with adequate n-6 and n-3 PUFA given during the lactating period to rats originating from alpha-linolenic acid-deficient dams was able to restore both the fatty acid composition of brain membranes and several parameters of the dopaminergic and serotonergic neurotransmission, and (ii) when given from weaning, this reversal diet allowed partial recovery of biochemical parameters, but no recovery of neurochemical factors. The occurrence of profound n-3 PUFA deficiency during the lactating period could therefore be an environmental insult leading to irreversible damage to specific brain functions. Strong evidence is now showing that a profound n-3 PUFA experimental deficiency is able to alter several neurotransmission systems, at least the dopaminergic and serotonergic. Whether these experimental findings can be transposed to human pathophysiology must be taken cautiously, but reinforces the hypothesis that strong links exist between the PUFA status, aspects of brain function such as neurotransmission processes and behavior.

Omega-3 fatty acids and perinatal depression: a review of the literature and recommendations for future research

INTRODUCTION

Perinatal depression refers to major depression in the context of pregnancy and postpartum. In consideration of its prevalence and consequences, the treatment and prevention of perinatal depression should be important public health priorities. Omega-3 fatty acids are attractive for consideration in perinatal women, due to known health benefits for the mother and baby. Antidepressant medications may pose risks in utero and in breastfeeding.

METHODS

MEDLINE and manual searches were conducted.

RESULTS

Epidemiological and preclinical data support a role of omega-3 fatty acids in perinatal depression. Two studies failed to support a role of omega-3 fatty acids for postpartum depression prophylaxis, although one included a small sample, and the other utilized a low dosage. Two pilot studies suggest good tolerability and potential efficacy in the acute treatment of perinatal depression.

CONCLUSIONS

Further research studies are warranted to determine the role of omega-3 fatty acids in the treatment of perinatal depression.

Long-chain polyunsaturated fatty acids in maternal and infant nutrition

Homo sapiens has evolved on a diet rich in alpha-linolenic acid and long chain polyunsaturated fatty acids (LCP). We have, however, gradually changed our diet from about 10,000 years ago and accelerated this change from about 100 to 200 years ago. The many dietary changes, including lower intake of omega3-fatty acids, are related to 'typically Western' diseases. After a brief introduction in essential fatty acids (EFA), LCP and their functions, this contribution discusses our present low status of notably LCPomega3 in the context of our rapidly changing diet within an evolutionary short time frame. It then focuses on the consequences in pregnancy, lactation and neonatal nutrition, as illustrated by some recent data from our group. We discuss the concept of a 'relative' EFA/LCP deficiency in the fetus as the outcome of high transplacental glucose flux. This flux may in the fetus augment de novo synthesis of fatty acids, which not only dilutes transplacentally transported EFA/LCP, but also causes competition of de novo synthesized oleic acid with linoleic acid for delta-6 desaturation. Such conditions were encountered by us in mothers with high body mass indices, diabetes mellitus and preeclampsia. The unifying factor might be compromised glucose homeostasis. In search of the milk arachidonic acid (AA) and docosahexaenoic acid (DHA) contents of our African ancestors, we investigated women in Tanzania with high intakes of freshwater fish as only animal lipid source. These women had milk AA and DHA contents that were well above present recommendations for infant formulae. Both studies stimulate rethinking of 'optimal homeostasis'. Subtle signs of dysbalanced maternal glucose homeostasis may be important and observations from current Western societies may not provide us with an adequate basis for dietary recommendations.

Impact of different saturated fatty acid, polyunsaturated fatty acid and cholesterol containing diets on beta-amyloid accumulation in APP/PS1 transgenic mice

The present study assessed the influence of dietary lipids on accumulation of amyloid beta-peptide (Abeta) in the brain. Seven experimental diets with varying n-6/n-3-ratio, saturated and polyunsaturated fatty acid and cholesterol contents were fed to transgenic APPswe/PS1dE9 mice for 3-4 months beginning at a young adult age (6 months). Hippocampal Abeta levels were determined with ELISA and plaque load by using immunocytochemistry. A typical Western diet with 40% saturated fatty acids and 1% of cholesterol increased, while diets supplemented with docosahexaenoic acid (DHA) decreased Abeta levels compared to regular (soy oil based) diet. DHA diet also decreased the number of activated microglia in hippocampus and increased exploratory activity of transgenic mice, but did not improve their spatial learning in the water maze. The favorable effect of DHA on Abeta production was verified in two different cell lines. Regulation of dietary lipid intake may offer a new tool to reduce the risk of Alzheimer's disease at the population level.

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.

Maternal dietary (n-3) fatty acid deficiency alters neurogenesis in the embryonic rat brain

Docosahexaenoic acid [22:6(n-3)] is enriched in brain membrane phospholipids and essential for brain function. Neurogenesis during embryonic and fetal development requires synthesis of large amounts of membrane phospholipid. We determined whether dietary (n-3) fatty acid deficiency during gestation alters neurogenesis in the embryonic rat brain. Female rats were fed diets with 1.3% energy [(n-3) control] or 0.02% energy [(n-3) deficient], from alpha-linolenic acid [18:3(n-3)], beginning 2 wk before gestation. Morphometric analyses were performed on embryonic day 19 to measure the mean thickness of the neuroepithelial proliferative zones corresponding to the cerebral cortex (ventricular and subventricular zones) and dentate gyrus (primary dentate neuroepithelium), and the thickness of the cortical plate and sectional area of the dentate gyrus. Phospholipids and fatty acids were determined by HPLC and GLC. Docosahexaenoic acid was 55-65% lower and (n-6) docosapentaenoic acid [22:5(n-6)] was 150-225% higher in brain phospholipids at embryonic day 19 in the (n-3) deficient (n = 6 litters) than in the control (n = 5 litters) group. The mean thickness of the cortical plate and mean sectional area of the primordial dentate gyrus were 26 and 48% lower, respectively, and the mean thicknesses of the cortical ventricular zone and the primary dentate neuroepithelium were 110 and 70% higher, respectively, in the (n-3) deficient than in the control embryonic day 19 embryos. These studies demonstrate that (n-3) fatty acid deficiency alters neurogenesis in the embryonic rat brain, which could be explained by delay or inhibition of normal development.

Folate and long-chain polyunsaturated fatty acids in psychiatric disease

Schizophrenia, autism and depression do not inherit by Mendel's law, and the search for a genetic basis seems unsuccessful. Schizophrenia and autism relate to low birth weight and pregnancy complications, which are associated with developmental adaptations by "programming". Epigenetics might constitute the basis of programming and depend on folate status and one-carbon metabolism in general. Early folate status of patients with schizophrenia might be compromised as suggested by (i) coinciding incidences of schizophrenia and neural tube defects (NTDs) in the Dutch hunger winter, (ii) coinciding seasonal fluctuations in birth of patients with schizophrenia and NTDs, (iii) higher schizophrenia incidence in immigrants and (iv) higher incidence in methylene tetrahydrofolate reductase 677C-->T homozygotes. Recent studies in schizophrenia and autism point at epigenetic silencing of critical genes or chromosomal loci. The long-chain polyunsaturated fatty acids (LCPUFA), arachidonic acid (AA, from meat) and docosahexaenoic acid (fish) are components of brain phospholipids and modulators of signal transduction and gene expression. Patients with schizophrenia and, possibly, autism exhibit abnormal phospholipid metabolism that might cause local AA depletion and impaired eicosanoid-mediated signal transduction. National fish intakes relate inversely with major and postpartum depressions. Five out of six randomized controlled trials with eicosapentaenoic acid (fish) have shown positive effects in schizophrenia, and 4 of 6 were favorable in depression and bipolar disorders. We conclude that folate and LCPUFA might be important in both the etiology and severity of at least some psychiatric diseases.

How dietary arachidonic- and docosahexaenoic- acid rich oils differentially affect the murine hepatic transcriptome

Introduction

Herein, we expand our previous work on the effects of long chain polyunsaturated fatty acids (LC-PUFA) on the murine hepatic transcriptome using novel statistical and bioinformatic approaches for evaluating microarray data. The analyses focuses on key differences in the transcriptomic response that will influence metabolism following consumption of FUNG (rich in 20:4n6), FISH (rich in 20:5n3, 22:5n3, and 22:6n3) and COMB, the combination of the two.

Results

Using a variance-stabilized F-statistic, 371 probe sets (out of 13 K probe sets in the Affymetrix Mu11K chip set) were changed by dietary treatment (P < 0.001). Relative to other groups, COMB had unique affects on murine hepatic transcripts involved in cytoskeletal and carbohydrate metabolism; whereas FUNG affected amino acid metabolism via CTNB1 signaling. All three diets affected transcripts linked to apoptosis and cell proliferation, with evidence FISH may have increased apoptosis and decreased cell proliferation via various transcription factors, kinases, and phosphatases. The three diets affected lipid transport, lipoprotein metabolism, and bile acid metabolism through diverse pathways. Relative to other groups, FISH activated cyps that form hydroxylated fatty acids known to affect vascular tone and ion channel activity. FA synthesis and delta 9 desaturation were down regulated by COMB relative to other groups, implying that a FA mixture of 20:4n6, 20:5n3, and 22:6n3 is most effective at down regulating synthesis, via INS1, SREBP, PPAR alpha, and TNF signaling. Heme synthesis and the utilization of heme for hemoglobin production were likely affected by FUNG and FISH. Finally, relative to other groups, FISH increased numerous transcripts linked to combating oxidative such as peroxidases, an aldehyde dehydrogenase, and heat shock proteins, consistent with the major LC-PUFA in FISH (20:5n3, 22:5n3, 22:6n3) being more oxidizable than the major fatty acids in FUNG (20:4n6).

Conclusion

Distinct transcriptomic, signaling cascades, and predicted affects on murine liver metabolism have been elucidated for 20:4n6-rich dietary oils, 22:6n3-rich oils, and a surprisingly distinct set of genes were affected by the combination of the two. Our results emphasize that the balance of dietary n6 and n3 LC-PUFA provided for infants and in nutritional and neutraceutical applications could have profoundly different affects on metabolism and cell signaling, beyond that previously recognized.

Lipids and the pathogenesis of Alzheimer's disease: is there a link?

Alzheimer's disease (AD) is a heterogeneous neurodegenerative disorder characterized pathologically by amyloid-beta plaques, neurofibrillary tangles and neuronal loss. Its fundamental cause(s) and the pathological cascades leading to clinical symptoms remain unknown. Lipids and lipid peroxidation products have important roles in the homeostasis of the central nervous system. As well, lipid transport genes and vascular changes associated with peripheral dyslipidemia have been associated with an increased risk of AD. The present review discusses ways in which lipids may be involved in the pathogenesis of AD-associated neurodegeneration through their roles as neuronal structural components, cell modulators, or second messengers. Given the many possibilities through which lipids may be directly involved in or contribute to the pathogenesis of AD, the use of lipids as biomarkers for disease progression is discussed, as are other avenues for future research.

Impact of venlafaxine on gene expression profile in lymphocytes of the elderly with major depression--evolution of antidepressants and the role of the "neuro-immune" system

Antidepressive drugs offer considerable symptomatic relief in mood disorders and, although commonly discovered by screening with single biological targets, most interact with multiple receptors and signaling pathways. Antidepressants require a treatment regimen of several weeks before clinical efficacy is achieved in patient populations. While the biochemical mechanisms underlying the delayed temporal profile remain unclear, molecular adaptations over time are likely involved. The selective serotonin and noradrenaline reuptake inhibitor, venlafaxine, offers a dual antidepressive action. Its pharmacological behavior, however, is unknown at the genetic level, and it is difficult to monitor in human brain samples. Because the hypothalamic-pituitary-adrenal axis is often severely disrupted in mood disorders, lymphocytes may serve as models of neuropsychiatric conditions. As such, we examined the role of venlafaxine on the gene expression profile of human lymphocytes. DNA microarray was used to measure the expression patterns of multiple genes in human lymphocytes from depressed patients treated with this mood stabilizer. In this self-controlled study, RNAs of control and treated samples were purified, converted into cDNA and labeled with either Cy3 or Cy5, mixed and hybridized to DNA microarrays containing human oligonucleotides corresponding to more than 8,000 genes. Genes that were differentially regulated in response to treatment were selected for follow up on the basis on novelty, gene identity, and level of over-expression/repression, and selected transcripts were profiled by real-time PCR (data have been normalized to beta-actin). Using software analysis of the microarray data, a number of transcripts were differentially expressed between control and treated samples, of which only 57 were found to significantly vary with the "P" value of 0.05 or lower as a result of exposure to venlafaxine. Of these, 31 genes were more highly expressed and 26 transcripts were found to be significantly less abundant. Most selected genes were verified with QRT-PCR to alter. As such, independent verification using QRT-PCR demonstrated the reliability of the method. Genes implicated in ionic homeostasis were differentially expressed, as were genes associated with cell survival, neural plasticity, signal transduction, and metabolism. Understanding how gene expression is altered over a clinically relevant time course of administration of venlafaxine may provide insight into the development of antidepressant efficacy as well as the underlying pathology of mood disorders. These changes in lymphocytes are thought to occur in the brain, and a "neuro-immune system" is proposed by this study.

Docosahexaenoic acid, fatty acid-interacting proteins, and neuronal function: breastmilk and fish are good for you

In contrast to other tissues, the nervous system is enriched in the polyunsaturated fatty acids (PUFAs): arachidonic acid (AA, 20:4 n-6) and docosahexaenoic acid (DHA, 22:6 n-3). Despite their abundance in the nervous system, AA and DHA cannot be synthesized de novo by mammals; they, or their precursors, must be ingested from dietary sources and transported to the brain. During late gestation and the early postnatal period, neurodevelopment is exceptionally rapid, and substantial amounts of PUFAs, especially DHA, are critical to ensure neurite outgrowth as well as proper brain and retina development. Here, we review the various functions of DHA in the nervous system, the proteins involved in its internalization and metabolism into phospholipids, and its relationship to several neurological disorders, including Alzheimer's disease and depression.

The impact of diet and exercise on brain plasticity and disease

Lifestyle involves our preference to engage in behaviors that can remarkably influence the fitness level of our body and brain. Dietary factors are a powerful means to influence brain function on a daily basis. We have shown that the consumption of a diet rich in saturated fat decreases learning and memory and increases metabolic distress. Conversely, diets supplemented either with omega-3 fatty acids, vitamin E or the curry spice curcumin benefit cognitive function. Equally impressive is the action of exercise on cognitive function as documented by studies showing that exercise enhances learning and memory. The beneficial action of exercise on the brain can be used therapeutically to overcome the effects of consuming a poor diet. We suggest that the managed use of diet and exercise can help the brain to cope with several types of insults and ultimately benefit brain function.

Nutrigenomic approaches to study the effects of n-3 PUFA diet in the central nervous system

Deficiencies in essential, mainly omega-3 and omega-6 (n-3, n-6) long chain polyunsaturated fatty acids (LC-PUFA) result in visual and cognitive impairment and disturbances in mental functions in animals and could be the main reason for the increasing incidence of different mental disorders in humans. Traditional approaches cannot give us a detailed picture on how dietary lipids exert their effects, because they focus on only a few genes or biomarkers. Dietary lipids not only influence the biophysical state of the cell membranes but, via direct and indirect routes, they also act on multiple pathways including signalling and gene and protein activities. Therefore, to understand the molecular basis of the effects and roles of n-3 PUFA in the central nervous system global screening techniques such as DNA- or protein microarrays were used to assess the changes, in a global way, at the transcriptome and at the proteome level. With DNA microarrays we found that cholesterol and fish oil (high in PUFA) diets altered the expression of several genes involved in raft formation and membrane protrusions. By using protein microarrays we detected a decreased concentration of protein kinase C beta, gamma, phospholipase C gamma and other changes in the expression level of proteins involved in the signal transduction pathway in the brain in response to high cholesterol diet. Besides the known cellular effects of lipid nutritions (changing eicosanoid make up, effects on membrane fluidity and raft stability) it is now evident that dietary lipids influence gene and protein activity levels, protein modifications and probably play important role in modulating protein aggregation.

Overexpression of dopamine receptor genes and their products in the postnatal rat brain following maternal n-3 fatty acid dietary deficiency

A combination of PCR-Select cDNA subtraction and gene array hybridization was used to identify differentially expressed genomic markers in brains of rats fed for 3 weeks in utero and 2 weeks after birth on an n-3 polyunsaturated fatty acid (PUFA)-deficient diet supplied to dams. Total RNA was isolated, switch mechanism at 5'-end of the RNA transcripts (SMART) applied and used for PCR-Select subtraction of PUFA-deficient and adequately-fed control preparations. Subtracted and amplified ds-cDNA end-products were fragmented, terminally labeled with biotin-ddUTP and hybridized with a RN-U34A gene array. A 10-fold increase in potential genes with log2(Tester/Driver) = 1.4 was found compared with traditional gene array technology when the same chip was tested using non-subtracted targets. Reverse transcription-real-time relative PCR confirmed 30% of the transcripts. Among the validated transcripts, D1 and D2 receptors for dopamine (DA), were most prominent among a number of over-expressed neurotransmitter receptors and retinoic acid receptor (RXR alpha-2 and alpha-1). Immunohistochemical staining of brain sections from 2-week-old pups revealed a substantial enrichment of the D2 receptor in discrete regions of the mesolimbic and mesocortical pathways as well as in a large number of brain areas from the n-3 PUFA-deficient pups. Punches of the same areas run on western blots showed similar results. The overwhelming expression of D1 and D2 receptors may be attributed to a behavioral hypersensitivity caused by the possible impairment of DA production during brain development, which may have implications in certain disorders of the nervous system.

Nutritional aspects modulating brain development and the responses to stress in early neonatal life

Nutrition is one of the critical factors insuring adequate growth and development in all species. In particular, brain development is sensitive to specific nutrient intake such as proteins and lipids, which are important for cell membrane formation and myelinization. Carbohydrate intake insures adequate short-term energy supply, but has important effects on the activity of the hypothalamic-pituitary-adrenal (HPA) axis to regulate stress responsiveness. This review focuses on the effects of carbohydrates and fat on the activity of the HPA axis as well as other brain-related functions such as pain modulation, neuropeptide and neurotransmitters release, and some aspects related to cognitive functions. The role of leptin, DHA and AA as mediators of the effects of fat on the brain is discussed.

(n-3) polyunsaturated fatty acid deficiency reduces the expression of both isoforms of the brain glucose transporter GLUT1 in rats

The altered neuron activity of rats deficient in (n-3) PUFAs may be due in part to a decrease in brain glucose utilization and glucose transport. We measured the glucose transporter protein GLUT1 isoforms at the blood-brain barrier (55-kDa) and in astrocytes (45-kDa) by Western immunoblotting and their mRNA by real time RT-PCR analysis in the cerebral cortex of adult male rats fed diets lacking (n-3) fatty acids (1st generation). The neuron glucose transporter GLUT3 was also assayed. The fatty acids in the phosphatidylcholine (PC), ethanolamine phosphoglycerolipid (EPG), and phosphatidylserine (PS) fractions of isolated microvessels and homogenates of the cerebral cortex were determined. The levels of (n-6) PUFAs [mainly arachidonic acid, 20:4(n-6)] in the phospholipid fractions of microvessels were higher and the levels of (n-3) PUFAs [mainly docosahexaenoic acid, 22:6(n-3)] were lower than in cerebral cortex homogenates. The microvessels and cortex of rats fed the (n-3) PUFA-deficient diet had 50% of the control 22:6(n-3) contents; 22:6(n-3) was replaced by 22:5(n-6). The 55-kDa GLUT1 immunoreactivity in (n-3) PUFA-deficient microvessels was decreased (down 25%, P < 0.01), as was the 45 kDa-GLUT1 in the homogenate (down 30%, P < 0.01). But the amount of immunoreactivity of GLUT3 did not change. The amount of GLUT1 mRNA was not affected by the (n-3) PUFA-deficient diet. These results suggest that the decreased glucose utilization in the cerebral cortex of (n-3) PUFA-deficient rats is due to reduced amounts of the 2 isoforms of GLUT1, indicating post-transcriptional regulation of GLUT1 synthesis.

Impact of haloperidol and risperidone on gene expression profile in the rat cortex

Despite the clinical efficacy of the most thoroughly studied conventional neuroleptic agent haloperidol, and the atypical antipsychotic risperidone is well established, little information is available on their molecular effects. Recent advances in high-density DNA microarray techniques allow the possibility to analyze thousands of genes simultaneously for their differential gene expression patterns in various biological processes, and to determine mechanisms of drug action. The aim of this series of experiments was to gain experience in antipsychotic gene-expression profiling and characterize (in the parlance of genomics) the "antipsychotic transcriptome." In this prospective animal study, broad-scale gene expression profiles were characterized for brains of rats treated with antipsychotics and compared with those of sham controls. We used DNA microarrays containing 8000 sequences to measure the expression patterns of multiple genes in rat fronto-temporo-parietal cortex after intraperitoneal treatment with haloperidol or risperidone. A number of transcripts were differentially expressed between control and treated samples, of which only 36 and 89 were found to significantly differ in expression as a result of exposure to haloperidol or risperidone, respectively (P<0.05). Acutely, 13 genes were more highly expressed and 15 transcripts were found to be significantly less abundant, whereas chronically nine genes were up-regulated and none of them was repressed in haloperidol-treated cortices. Risperidone acutely induced 43 and repressed 46 genes, and chronically over-expressed 6 and down-regulated 11 transcripts. Selected genes were assayed by real-time PCR, then normalized to beta-actin. These assays confirmed the significance of the array results for all transcripts tested. Despite their differing receptor affinity and selectivity, our findings indicate that haloperidol and risperidone interfere with cell survival, neural plasticity, signal transduction, ionic homeostasis and metabolism in a similar manner.

Cholesterol and cholesterol plus DHA diet-induced gene expression and fatty acid changes in mouse eye and brain

Both cholesterol and polyunsaturated fatty acid (PUFA) metabolism play an important role in retinal and brain development and function. Dietary intake of cholesterol is accompanied with higher risk of heart disease and was suggested to have a role in the pathogenesis of Alzheimer's disease, while dietary PUFAs were reported to act in an opposite way. The same phenomena could be seen in case of inflammation. These effects are mainly realized through gene expression changes. In the present study, the effects of dietary cholesterol and the combination of cholesterol and fish oil were analyzed on the modulation of fatty acid composition and gene expression in the brain and in the eye. At the transcription level, specific changes could be detected in both tissues among transcription factor genes coding for sterol regulatory element binding proteins, retinoid X receptors and peroxisome proliferator-activated receptors, and different fatty acid binding protein genes by using quantitative real-time PCR. In the eye, cholesterol diet attenuated the positive effects of fish oil on inflammatory gene expression as the combined diet resulted in increased RNAm level of phospholipase A-2, inducible nitric oxide synthase, TNF-alpha, COX-1, COX-2 and cytokine, ICAM-1. This induction was absent in the brain. Complex changes could be also recorded in the fatty acid composition of lipids extracted from eye and brain tissue due to the dietary intervention. One of the most interesting changes was the reduced level of docosahexaenoic acid by cholesterol in the eye. Our results on fatty acid composition and gene expression changes may open up new alleys in understanding the complex roles of cholesterol and PUFAs in normal and pathological visual and brain function.

Perinatal omega-3 polyunsaturated fatty acid supply modifies brain zinc homeostasis during adulthood

Dietary omega-3 polyunsaturated fatty acid (PUFA) influences the expression of a number of genes in the brain. Zinc transporter (ZnT) 3 has been identified as a putative transporter of zinc into synaptic vesicles of neurons and is found in brain areas such as hippocampus and cortex. Neuronal zinc is involved in the formation of amyloid plaques, a major characteristic of Alzheimer's disease. The present study evaluated the influence of dietary omega-3 PUFA on the expression of the ZnT3 gene in the brains of adult male Sprague-Dawley rats. The rats were raised and/or maintained on a control (CON) diet that contained omega-3 PUFA or a diet deficient (DEF) in omega-3 PUFA. ZnT3 gene expression was analyzed by using real-time PCR, free zinc in brain tissue was determined by zinquin staining, and total zinc concentrations in plasma and cerebrospinal fluid were determined by atomic absorption spectrophotometry. Compared with CON-raised animals, DEF-raised animals had increased expression of ZnT3 in the brain that was associated with an increased level of free zinc in the hippocampus. In addition, compared with CON-raised animals, DEF-raised animals had decreased plasma zinc level. No difference in cerebrospinal fluid zinc level was observed. The results suggest that overexpression of ZnT3 due to a perinatal omega-3 PUFA deficiency caused abnormal zinc metabolism in the brain. Conceivably, the influence of dietary omega-3 PUFA on brain zinc metabolism could explain the observation made in population studies that the consumption of fish is associated with a reduced risk of dementia and Alzheimer's disease.

Does perinatal omega-3 polyunsaturated fatty acid deficiency increase appetite signaling?

OBJECTIVE

To investigate the effect of maternal dietary omega-3 polyunsaturated fatty acid (PUFA) deficiency and repletion on food appetite signaling.

RESEARCH METHODS AND PROCEDURES

Sprague-Dawley rat dams were maintained on diets either supplemented with (CON) or deficient in (DEF) omega-3 PUFA. All offspring were raised on the maternal diet until weaning. After weaning, two groups remained on the respective maternal diet (CON and DEF groups), whereas a third group, born of dams fed the DEF diet, were switched to the CON diet (REC). Experiments on food intake began when the male rats reached 16 weeks of age. Food intake was stimulated either by a period of food restriction, by blocking glucose utilization (by 2-deoxyglucose injection), or by blocking beta-oxidation of fatty acids (by beta-mercaptoacetate injection).

RESULTS

DEF animals consumed more than CON animals in response to all stimuli, with the greatest difference (1.9-fold) demonstrated following administration of 2-deoxyglucose. REC animals also consumed more than CON animals in response to food restriction and 2-deoxyglucose but not to beta-mercaptoacetate.

DISCUSSION

These findings indicate that supply of omega-3 PUFA, particularly during the perinatal period, plays a role in the normal development of mechanisms controlling food intake, especially glucoprivic (i.e. reduced glucose availability) appetite signaling. Dietary repletion of omega-3 PUFA from 3 weeks of age restored intake responses to fatty acid metabolite signaling but did not reverse those in response to food restriction or glucoprivic stimuli.

Chronic administration of docosahexaenoic acid ameliorates the impairment of spatial cognition learning ability in amyloid beta-infused rats

We investigated whether administration of docosahexaenoic acid (DHA), a major (n-3) fatty acid of the brain, ameliorates the impairment of learning ability in an animal model of Alzheimer's disease (AD), rats infused with amyloid-beta (Abeta) peptide (1-40) into the cerebral ventricle. Inbred 3rd generation male rats (20 wk old) fed a fish oil-deficient diet were randomly divided into 4 groups: a vehicle group, an Abeta peptide-infused group (Abeta group), a DHA group, and an Abeta + DHA group. A mini-osmotic pump filled with Abeta peptide or vehicle was implanted in the rats, and they were tested for learning ability-related reference and working memory in an 8-arm radial maze. The rats were then orally fed DHA dissolved in 5% gum Arabic solution at 300 mg/(kg . d) (DHA and Abeta + DHA groups) or vehicle alone (vehicle and Abeta groups) and tested again for learning ability. DHA administered for 12 wk significantly reduced the increase in the number of reference and working memory errors in the Abeta-infused rats, and increased both the cortico-hippocampal level of DHA and the molar ratio of DHA/arachidonic acid, suggesting an amelioration of the impaired spatial cognition learning ability. Furthermore, DHA suppressed the increases in the levels of lipid peroxide and reactive oxygen species in the cerebral cortex and the hippocampus of Abeta-infused rats, suggesting that DHA increases antioxidative defenses. DHA is thus a possible therapeutic agent for ameliorating learning deficiencies due to Alzheimer's disease.

Dietary omega-3 fatty acids normalize BDNF levels, reduce oxidative damage, and counteract learning disability after traumatic brain injury in rats

Omega-3 fatty acids (i.e., docosahexaenoic acid; DHA) regulate signal transduction and gene expression, and protect neurons from death. In this study we examined the capacity of dietary omega3 fatty acids supplementation to help the brain to cope with the effects of traumatic injury. Rats were fed a regular diet or an experimental diet supplemented with omega-3 fatty acids, for 4 weeks before a mild fluid percussion injury (FPI) was performed. FPI increased oxidative stress, and impaired learning ability in the Morris water maze. This type of lesion also reduced levels of brain-derived neurotrophic factor (BDNF), synapsin I, and cAMP responsive element-binding protein (CREB). It is known that BDNF facilitates synaptic transmission and learning ability by modulating synapsin I and CREB. Supplementation of omega-3 fatty acids in the diet counteracted all of the studied effects of FPI, that is, normalized levels of BDNF and associated synapsin I and CREB, reduced oxidative damage, and counteracted learning disability. The reduction of oxidative stress indicates a benevolent effect of this diet on mechanisms that maintain neuronal function and plasticity. These results imply that omega-3 enriched dietary supplements can provide protection against reduced plasticity and impaired learning ability after traumatic brain injury.

Primary aminophospholipids in the external layer of liposomes protect their component polyunsaturated fatty acids from 2,2'-azobis(2-amidinopropane)- dihydrochloride-mediated lipid peroxidation

We showed in our previous study that docosahexaenoic acid-rich phosphatidylethanolamine in the external layer of small-size liposomes, as a model for biomembranes, protected its docosahexaenoic acid from 2,2'-azobis(2-amidinopropane)dihydrochloride- (AAPH-) mediated lipid peroxidation in vitro. Besides phosphatidylethanolamine, both phosphatidylserine and an alkenyl-acyl analogue of phosphatidylethanolamine, phosphatidylethanolamine plasmalogen, are reported to possess characteristic antioxidant activities. However, there are few reports about the relationship between the protective activity of phosphatidylethanolamine plasmalogen and/or phosphatidylserine against lipid peroxidation and their distribution in a phospholipid bilayer. Furthermore, it is unclear whether phosphatidylethanolamine plasmalogen and/or phosphatidylserine protect their component polyunsaturated fatty acids (PUFAs) from lipid peroxidation. In the present study, we examined the relationship between the transbilayer distribution of aminophospholipids, such as phosphatidylethanolamine rich in arachidonic acid, phosphatidylethanolamine plasmalogen, and phosphatidylserine, and the oxidative stability of their component PUFAs. The transbilayer distribution of these aminophospholipids in liposomes was modulated by coexisting phosphatidylcholine bearing two types of acyl chain: dipalmitoyl or dioleoyl. The amounts of these primary aminophospholipids in the external layer became significantly higher in liposomes containing dioleoylphosphatidylcholine than in those containing dipalmitoylphosphatidylcholine. Phosphatidylethanolamine rich in arachidonic acid, phosphatidylethanolamine plasmalogen or phosphatidylserine in the external layer of liposomes, as well as external docosahexaenoic acid-rich phosphatidylethanolamine, were able to protect their component PUFAs from AAPH-mediated lipid peroxidation.

Altered response to mirtazapine on gene expression profile of lymphocytes from Alzheimer's patients

Antidepressants are widely used in the treatment of mood disorders associated with dementia, however little information is available on their effect at the molecular level. We have demonstrated that gene expression profiles of lymphocytes from patients with Alzheimer dementia differ from that seen with controls, with alpha(2)-adrenoceptor being the most highly repressed transcript. To address this issue in light of antidepressant treatment, we used lymphocytes derived from Alzheimer patients and control individuals to assess the impact of mirtazapine, the novel antidepressant with alpha(2)-adrenoceptor antagonistic activities, on gene expression using a cDNA microarray representing 3200 distinct human genes. Sequences that are differentially regulated after treatment with mirtazapine were identified and categorized based on similarities in biological functions. This analysis revealed that selected biological processes, including protein metabolism, cytoskeleton integrity, immune response, cellular plasticity, and neurotransmission, are involved in early phases of administration of this antidepressant. In addition, although it was possible to identify common targets, the expression profiles of Alzheimer lymphocytes differed mainly in their magnitude from those seen with controls. These results confirm the usefulness of the gene array approach for studying Alzheimer-specific changes in the periphery and suggest that the expression of genes of Alzheimer lymphocytes is modulated differently by mirtazapine, which correlates with the pathology.

Parallel expression of αIIbβ3 and αvβ3 integrins in human melanoma cells upregulates bFGF expression and promotes their angiogenic phenotype

Previous studies indicated that transfection of the platelet integrin alphaIIbbeta3 into human melanoma cells expressing integrin alphavbeta3 promoted their in vivo (but not in vitro) growth and cell survival. To reveal the underlying pathomechanism, we have analyzed the angiogenic phenotype of alphaIIbbeta3 integrin-transduced human melanoma cells expressing integrin alphavbeta3. Upon heterotopic or orthotopic (intracutaneous) injections into SCID mice, the alphaIIbbeta3 integrin-overexpressing clones, ESL, ESH, 19L and 19H, grew more rapidly than the mock transfectant (alphavbeta3 expressing) clone, 3.1P. Morphometry demonstrated an increased intratumoral microvessel density in 19L and 19H tumors compared to 3.1P. Immunocytochemistry and flow cytometry indicated that vascular endothelial growth factor (VEGF) is constitutively expressed in the majority of the cells of both the mock and the alphaIIbbeta3 integrin-transfected clones. However, the mock transfectant clone, 3.1P, did not express basic fibroblast growth factor (bFGF) at protein level (<1%), unlike the alphaIIbbeta3 integrin-transfected clones, 19L and 19H, (33.9 and 84.1%, respectively). Quantitative PCR analysis of 6 related human melanoma clones with various levels of alphaIIbbeta3 integrin expressions revealed a correlation between the alphaIIb protein and bFGF mRNA expressions. Furthermore, cDNA microarray analysis of the 19H cells revealed 12 downregulated and 36 upregulated genes [among them 3 upregulated vasculogenic mimicry-genes (CD34, endothelin receptor B, Prostaglandin I-2 synthase)] when compared to 3.1P cells. The altered bFGF expression may be influenced by integrin-linked signaling, since bbeta3-endonexin is upregulated in alphaIIbbeta3-transfected cells and tyrosine kinase inhibitors downregulate bFGF both at mRNA and protein levels. We propose here that the illegitimate expression of alphaIIbbeta3 integrin in human melanoma cells already expressing alphavbeta3 integrin may alter their in vivo growth properties due to the modulation of their angiogenic phenotype.

Omega-3 Fatty Acids in the Treatment of Psychiatric Disorders

The importance of omega-3 fatty acids for physical health is now well recognised and there is increasing evidence that omega-3 fatty acids may also be important to mental health. The two main omega-3 fatty acids in fish oil, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have important biological functions in the CNS. DHA is a major structural component of neuronal membranes, and changing the fatty acid composition of neuronal membranes leads to functional changes in the activity of receptors and other proteins embedded in the membrane phospholipid. EPA has important physiological functions that can affect neuronal activity. Epidemiological studies indicate an association between depression and low dietary intake of omega-3 fatty acids, and biochemical studies have shown reduced levels of omega-3 fatty acids in red blood cell membranes in both depressive and schizophrenic patients. Five of six double-blind, placebo-controlled trials in schizophrenia, and four of six such trials in depression, have reported therapeutic benefit from omega-3 fatty acids in either the primary or secondary statistical analysis, particularly when EPA is added on to existing psychotropic medication. Individual clinical trials have suggested benefits of EPA treatment in borderline personality disorder and of combined omega-3 and omega-6 fatty acid treatment for attention-deficit hyperactivity disorder. The evidence to date supports the adjunctive use of omega-3 fatty acids in the management of treatment unresponsive depression and schizophrenia. As these conditions are associated with increased risk of coronary heart disease and diabetes mellitus, omega-3 fatty acids should also benefit the physical state of these patients. However, as the clinical research evidence is preliminary, large, and definitive randomised controlled trials similar to those required for the licensing of any new pharmacological treatment are needed.

Statin treatment alters serum n-3 and n-6 fatty acids in hypercholesterolemic patients

Statins are highly effective cholesterol-lowering drugs but may have broader effects on metabolism. This investigation examined effects of simvastatin on serum levels of n-6 and n-3 polyunsaturated fatty acids (PUFAs). Subjects were 106 healthy adults with hypercholesterolemia randomly assigned to receive placebo or 40 mg simvastatin daily for 24 weeks. Serum fatty acids were analyzed by gas chromatography. Total fatty acid concentration fell 22% in subjects receiving simvastatin (P<.001), with similar declines across most fatty acids. However, concentrations of arachidonic acid (AA, 20:4n-6), eicosapentanoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) were unchanged. Relative percentages of linoleic acid (LA, 18:2n-6) and alpha-linolenic acid (LNA, 18:3n-3), decreased while AA and DHA increased (P's < or = .007). In addition, simvastatin increased the AA:EPA ratio from 15.5 to 18.8 (P<.01), and tended to increase the AA:DHA ratio (P=.053). Thus, simvastatin lowered serum fatty acid concentrations while also altering the relative percentages of important PUFAs.

The effect of citalopram on gene expression profile of Alzheimer lymphocytes

Antidepressants are widely used in the treatment of mood disorders associated with dementia, however little information is available on their effect at the molecular level. In certain neurodegenerative disorders, such as in Alzheimer's disease, lymphocytes have been used to assess mirror changes that thought to occur in the brain. Gene expression profiles of lymphocytes from Alzheimer patients have been shown to differ from that seen with controls. To address this issue in light of antidepressant treatment, we used lymphocytes derived from Alzheimer's disease patients and control individuals to assess the impact of the selective serotonine reuptake inhibitor citalopram on gene expression using a cDNA microarray representing 3200 distinct human genes. Sequences that are differentially regulated after treatment with citalopram were identified and categorized based on similarities in biological functions. This analysis revealed that the overexpression of genes in control and Alzheimer white blood cells by citalopram are implicated in cell survival. Apart from this, citalopram did not markedly alter genes involved in other molecular functions in control cells. In contrast, alteration of genes implicated in ionic currents, cell-adhesion, immune mechanism, and adrenergic functions, were also observed in Alzheimer lymphocytes. The expression of genes of Alzheimer lymphocytes by citalopram is modulated differently which may correlate with the pathology.

Temporal changes in cerebral antioxidant enzyme activities after ischemia and reperfusion in a rat focal brain ischemia model: effect of dietary fish oil

This study investigated the neuroprotective effects of dietary supplementation of fish oil on both brain infarction and the activities of antioxidant enzymes. Male Sprague-Dawley rats (4-weeks old) were divided into two groups and received either a regular diet (RD) or a fish-oil-supplemented diet (FOD) for 6 weeks prior to middle cerebral artery (MCA) occlusion. The infarction volume of the brain was calculated using image analysis after staining. Antioxidant enzymes were measured before ischemia (BI), after 2 h of ischemia (AI) and after 24 h (24hR), 48 h (48hR) and after 7 days (7dR) of reperfusion. The infarction volume of the brain was significantly smaller in the FOD group than in the RD group after 24 h of reperfusion (p<0.05). Before ischemia, the levels of lipid peroxide and the glutathione peroxidase (GPx) activity were higher in the FOD group than in the RD group. During reperfusion, the catalase (CAT) activity in the FOD group remained at the preischemia level until after 48 h of reperfusion, while those in the RD group did not. The Mn-superoxide dismutase (SOD) activity and GPx activity were higher in the FOD group than in the RD group only after 2 h of ischemia. In the fatty acid analysis, the ratio of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) were higher in the FOD group than in the RD group (p<0.05). Our results demonstrate that supplementing the diet with fish oil could decrease the cerebral infarction volume following ischemia and reperfusion (I/R) partly by working directly as an antioxidant and partly by modulating antioxidant enzyme activities.

Effects of dietary omega-3 polyunsaturated fatty acids on brain gene expression

Polyunsaturated fatty acids (PUFA) are essential structural components of the central nervous system. Their role in controlling learning and memory has been well documented. A nutrigenomic approach with high-density microarrays was used to reveal brain gene-expression changes in response to different PUFA-enriched diets in rats. In aged rats fed throughout life with PUFA-enriched diets, genes with altered expressions included transthyretin, alpha-synuclein, and calmodulins, which play important roles in synaptic plasticity and learning. The effect of perinatal omega-3 PUFA supply on gene expression later in life also was studied. Several genes showed similar changes in expression in rats fed omega-3-deficient diets in the perinatal period, regardless of whether they or their mothers were fed omega-3 PUFA-sufficient diets after giving birth. In this experiment, among the down-regulated genes were a kainate glutamate receptor and a DEAD-box polypeptide. Among the up-regulated genes were a chemokine-like factor, a tumor necrosis factor receptor, and cytochrome c. The possible involvement of the genes with altered expression attributable to different diets in different brain regions in young and aged rats and the possible mode of regulatory action of PUFA also are discussed. We conclude that PUFA-enriched diets lead to significant changes in expression of several genes in the central nervous tissue, and these effects appear to be mainly independent of their effects on membrane composition. The direct effects of PUFA on transcriptional modulators, the downstream developmentally and tissue-specifically activated elements might be one of the clues to understanding the beneficial effects of the omega-3 PUFA on the nervous system.

Serotoninergic neurotransmission is affected by n-3 polyunsaturated fatty acids in the rat

We explored the effects of chronic alpha-linolenic acid dietary deficiency on serotoninergic neurotransmission. In vivo synaptic serotonin (5-HT) levels were studied in basal and pharmacologically stimulated conditions using intracerebral microdialysis in the hippocampus of awake 2-month-old rats. We also studied the effects of reversion of the deficient diet on fatty acid composition and serotoninergic neurotransmission. A balanced (control) diet was supplied to deficient rats at different stages of development, i.e. from birth, 7, 14 or 21 days of age. We demonstrated that chronic n-3 polyunsaturated fatty acid dietary deficiency induced changes in the synaptic levels of 5-HT both in basal conditions and after pharmacological stimulation with fenfluramine. Higher levels of basal 5-HT release and lower levels of 5-HT-stimulated release were found in deficient than in control rats. These neurochemical modifications were reversed by supply of the balanced diet provided at birth or during the first 2 weeks of life through the maternal milk, whereas they persisted if the balanced diet was given from weaning (at 3 weeks of age). This suggests that provision of essential fatty acids is durably able to affect brain function and that this is related to the developmental stage during which the deficiency occurs.

A placebo-controlled cross-over trial of adjunctive EPA in OCD

Several clinical studies showed beneficial effects of omega-3 fatty acids in major affective disorders, including resistant depression. Some antidepressants are also effective, albeit less so, in obsessive-compulsive disorder (OCD). We therefore undertook a preliminary placebo-controlled cross-over trial of adjunctive eicosapentaenoic acid (EPA) in OCD. Eleven patients with current obsessive-compulsive disorder, who were on a stable maximally tolerated dose of SSRI with no further improvement over at least the last two months, were recruited. Subjects were randomly allocated to begin 6 weeks of placebo (2 g liquid paraffin per day) followed by 6 weeks of 2 g of EPA or EPA followed by placebo. Patients continued their prior SSRIs at the same dose. Assessments were performed with the Yale-Brown Obsessive-Compulsive Scale (YBOCS), and the Hamilton Rating Scales for depression (HAM-D) and anxiety (HAM-A). There were no effects of order of treatment. Time had a main effect of YBOCS scores; mean scores declined from 26.0 (+/-5) to 17.6 (+/-6) by week 6 on placebo and to 18.5 (+/-4) on EPA. There were no effects on HAM-D and HAM-A. No clinically relevant side effects were reported. The results of this study suggest that adjunctive EPA is ineffective against OCD.

Docosahexaenoic acid in the diet: its importance in maintenance and restoration of neural membrane function

The central nervous system has the second highest concentration of lipids after adipose tissue. Long chain fatty acids, particularly arachidonic acid and docosahexaenoic acid, are integral components of neural membrane phospholipids. Alterations in neural membrane phospholipid components cannot only influence crucial intracellular and intercellular signaling but also alter many membrane physical properties such as fluidity, phase transition temperature, bilayer thickness, and lateral domains. A deficiency of docosahexaenoic acid markedly affects neurotransmission, membrane-bound enzyme and ion channel activities, gene expression, intensity of inflammation, and immunity and synaptic plasticity. Docosahexaenoic acid deficiency is associated with normal aging, Alzheimer disease, hyperactivity, schizophrenia, and peroxisomal disorders. Although the molecular mechanism of docosahexaenoic acid involvement in the disorders remains unknown, the supplementation of docosahexaenoic acid in the diet restores gene expression and modulates neurotransmission. Also, improvements are seen in signal transduction processes associated with behavioral deficits, learning activity, peroxisomal disorders, and psychotic changes in schizophrenia, depression, hyperactivity, stroke, and Alzheimer disease.

Polyunsaturated fatty acids and gene expression

PURPOSE OF REVIEW

This review focuses on the effect(s) of n-3 polyunsaturated fatty acids on gene transcription as determined by data generated using cDNA microarrays. Introduced within the past decade, this methodology allows detection of the expression of thousands of genes simultaneously and, hence, is a potentially powerful tool for studying the regulation of physiological mechanisms that are triggered or inhibited by nutrients.

RECENT FINDINGS

Recent data generated with cDNA microarrays not only confirm the effects of n-3 polyunsaturated fatty acids on regulation of lipolytic and lipogenic gene expression as determined by more traditional methods but also emphasize the tissue specificity of this regulation. cDNA microarray experiments also have expanded our understanding of the role of n-3 polyunsaturated fatty acids in regulation of expression of genes involved in many other pathways. These include: oxidative stress response and antioxidant capacity; cell proliferation; cell growth and apoptosis; cell signaling and cell transduction.

SUMMARY

The cDNA microarray studies published to date show clearly that n-3 polyunsaturated fatty acids, usually provided as fish oil, modulate expression of a number of genes with such broad functions as DNA binding, transcriptional regulation, transport, cell adhesion, cell proliferation, and membrane localization. These effects, in turn, may significantly modify cell function, development and/or maturation.

Cholesterol diet-induced hyperlipidemia influences gene expression pattern of rat hearts: a DNA microarray study

To profile gene expression patterns involved in the direct myocardial effect of cholesterol-enriched diet-induced hyperlipidemia, we monitored global gene expression changes by DNA microarray analysis of 3200 genes in rat hearts. Twenty-six genes exhibited significant up-regulation and 25 showed down-regulation in hearts of rats fed a 2% cholesterol-enriched diet for 8 weeks as compared to age-matched controls. The expression changes of 12 selected genes were also assessed by real-time quantitative polymerase chain reaction. Genes with altered expression in the heart due to hyperlipidemia included procollagen type III, cofilin/destrin, tensin, transcription repressor p66, synaptic vesicle protein 2B, Hsp86, chaperonin subunit 5epsilon, metallothionein, glutathione S-transferase, protein kinase C inhibitor, ATP synthase subunit c, creatine kinase, chloride intracellular channel 4, NADH oxidoreductase and dehydrogenase, fibronectin receptor beta chain, CD81 antigen, farnesyltransferase, calreticulin, disintegrin, p120 catenin, Smad7, etc. Although some of these genes have been suspected to be related to cardiovascular diseases, none of the genes has been previously shown to be involved in the mechanism of the cardiac effect of hyperlipidemia.

Dietary ethyl-eicosapentaenoic acid but not soybean oil reverses central interleukin-1-induced changes in behavior, corticosterone and immune response in rats

Omega (n)-3 and n-6 fatty acids are important membrane components of neurons and immune cells, and related to psychiatric and inflammatory diseases. Increased ratio of n-6/n-3 in the blood has been reported in depressed patients and in students following stress exposure. The n-3 fatty acid, eicosapentaenoic acid (ethyl-EPA) suppresses inflammation and has antidepressant properties. Interleukin (IL)-1beta can stimulate corticosterone secretion, induce anxiety and stress-like behavior and inflammatory responses. This study was to evaluate the effect of diets enriched with coconut oil, ethyl-EPA and soybean oil on central IL-1beta induced stress and anxiety-like behavior, induced changes in the concentration of prostaglandin (PG) E2 and corticosterone and the release of IL-10. Groups of rats were fed with either 5% coconut oil (as control diet), 0.2% EPA with 4.8% coconut oil or 1% EPA with 4% coconut oil and 5% soybean oil for 7 weeks. The central administration of IL-1beta induced sickness, stress and anxiety-like behavior as indicated by a reduction in body weight, decreased time spent, and the number of entries, into the open arms of the elevated plus maze and decreased exploration and entry into the central zone of the "open field" apparatus. IL-1beta also increased PGE2 and corticosterone concentrations and decreased the release of IL-10 from leucocytes. Food enriched with ethyl-EPA but not soybean oil, significantly attenuated most of these changes. These results demonstrate that ethyl-EPA has anti-inflammatory, anti-stress and anti-anxiety effects in rats.

Fish consumption, blood docosahexaenoic acid and chronic diseases in Chinese rural populations

The Chinese traditional diet is low in fat. However, there is regional variability in the amount, type of fat consumed and the pattern of chronic diseases. An epidemiological survey of 65 rural counties in China (6500 subjects) was conducted in the 1980s. We have re-examined the red blood cell fatty acid and antioxidant composition, with fish consumption. Fish consumption correlated significantly with the levels of docosahexaenoic acid (DHA) in red blood cells (RBC) (r=0.640, P<0.001), selenium (r=0.467, P<0.001) and glutathione peroxidase (r=0.333, P<0.01) in plasma. The proportion of DHA in RBC was inversely associated with total plasma triglyceride concentrations. A strong inverse correlation between DHA in RBC and cardiovascular disease (CVD) was found. The strongest correlation was the combination of DHA and oleic acid. RBC docosahexaenoic acid itself also correlated negatively and significantly with most chronic diseases and appeared to be more protective than either eicosapentaenoic or the omega3 docosapenataenoic acids. These results demonstrate the protective nature of fish consumption and DHA, found in high fat Western diets, operates at a low level of fat. This finding suggests the protective effect of fish consumption as validated by red cell DHA is universal. The protective effect is, therefore, most likely to be due to the fundamental properties of docosahexaenoic acid in cell function.

Stimulation of myelin proteolipid protein gene expression by eicosapentaenoic acid in C6 glioma cells

In this study, the role of exogenous fatty acids in the regulation of proteolipid protein (PLP) gene expression was investigated using the following model culture system: C6 glioma cells expressing the green-fluorescent protein (eGFP) driven by different segments of PLP promoter. Eicosapentanoic acid (EPA; 20:5 n-3), but not arachidonic acid (AA; 20:4 n-6), induced a significant increase in medium fluorescence intensity (MFI) determined by fluorescence-activated cell sorting (FACS). The induction of PLP promoter was time-dependent showing maximal activity between 24 and 48 h after EPA exposure. PLP promoter activation was dependent on fatty acid concentration, with maximum activation at 200 microM. Northern blot analysis confirmed the fluorescence data in C6 cells incubated with EPA. Furthermore, this treatment increased the adenylyl cyclase-cyclic AMP (cAMP) levels and the mitogen-activated protein kinase (MAPK) activation in C6 cells. PLP promoter activity was inhibited by pre-treatment with H89 (protein kinase A (PKA) inhibitor), but not with PD98059 (MAPK inhibitor), suggesting that EPA stimulates the expression of PLP via cAMP-mediated pathways.

Polyunsaturated Fatty Acids in Human Milk

The n-6 and n-3 fatty acids are essential dietary nutrients required for optimal growth and development, particularly of the brain and retina. Large amounts of the n-3 fatty acid docosahexaenoic acid (DHA) is accumulated in the brain grey matter and the visual elements of the retina during development, and reduced DHA in these tissues can result in decreased visual and psychomotor development. Although the possible importance of differences in n-6 and n-3 fatty acids, particularly DHA, between human milk and infant formulas has been the subject of intense clinical research, the variability in the essential fatty acid content of milk within and among different populations of women and implications of this to infant growth and development have received much less attention. Considerable research has shown that the DHA content of the maternal diet is the most important determinant of the amount of DHA secreted in milk, and thus the dietary intake of the breastfed infant. The DHA content of human milk varies over 10-fold, being lowest in women with no intake of DHA and highest in women with high intakes of DHA, which is found predominantly in fatty fish. The requirement for n-3 fatty acids, and the balance of n-6 and n-3 fatty acids for optimal growth and development of the brain and retina, and long-term minimization of risk of chronic disease remains as one of the most important questions in infant nutrition. Dietary recommendations to modifying dietary fat with the aim of reducing risk of chronic disease, including obesity and cardiovascular disease in adults, need to consider that when followed by pregnant women, these recommendations can have a marked effect on the amount and balance of n-6 and n-3 fatty acids secreted in milk.

Impaired expression of acyl-CoA-synthetase 5 in epithelial tumors of the small intestine

Fatty acids are implicated in tumorigenesis, but data are limited concerning endogenous fatty acid metabolism of tumor cells in adenomas and adenocarcinomas of the small intestine. The recently cloned human acyl-CoA-synthetase 5 (ACS5) is predominantly found in the small intestine and represents a key enzyme in providing cytosolic acyl-CoA thioesters. Protein synthesis and mRNA expression of ACS5 were studied in human intestinal tissues using different methods, including a newly established monoclonal antibody. In the healthy small intestine, expression of ACS5 was restricted to the villus surface epithelium but was not detectable in enterocytes lining crypts. ACS5 protein and mRNA were progressively diminished in epithelial cells of adenomas and adenocarcinomas of the small intestine. In conclusion, altered expression of ACS5 is probably related to the adenoma-carcinoma sequence of small intestinal epithelial tumors due to an impaired acyl-CoA thioester synthesis.

Perinatal biochemistry and physiology of long-chain polyunsaturated fatty acids

Docosahexaenoic acid (DHA) and arachidonic acid (ARA) are important structural components of the central nervous system. These fatty acids are transferred across the placenta, are present in human milk, and are accumulated in the brain and retina during fetal and infant development. The high concentrations of DHA in the retina and of DHA and ARA in brain gray matter suggests that these fatty acids have important roles in retinal and neural function. Animal studies have shown that depletion of DHA from the retina and brain results in reduced visual function and learning deficits. The latter effects may be explained by changes in the membrane bilayer that alter membrane-associated receptors and signal transduction systems, ion channel activity, or direct effects on gene expression. DHA can be formed in the liver from alpha linolenic acid, but it is unclear if the rate of DHA synthesis in humans is sufficient to support optimal brain and retinal development. Although there is no evidence that the ability to form ARA from linoleic acid is limiting, supplementation with DHA reduces tissue ARA, possibly creating a conditional need for ARA in infants with a dietary intake of DHA. The amount of DHA in human milk varies widely and is positively correlated with visual and language development in breast-fed infants. Advances in understanding essential fatty acid requirements will benefit from intervention studies that use functionally relevant tests to probe the deficiency or adequacy of physiologically important pools of DHA and ARA in developing infants.

Modification by docosahexaenoic acid of age-induced alterations in gene expression and molecular composition of rat brain phospholipids

Advanced age is associated with reduced brain levels of long-chain polyunsaturated fatty acids, arachidonic acid (AA) and docosahexaenoic acid (DHA). Memory impairment is also a common phenomenon in this age. Two-year-old, essential fatty acid-sufficient rats were fed with fish oil (11% DHA) for 1 month, and fatty acid as well as molecular composition of the major phospholipids, phosphatidylcholine and phosphatidylethanolamine (PE), was compared with that of 2-month-old rats on the same diet. DHA but not AA was significantly reduced in brains of old rats but was restored to the level of young rats when they received rat chow fortified with fish oil. This effect was pronounced with diacyl 18:0/22:6 PE species, whereas levels of 18:1/22:6 and 16:0/22:6 remained unchanged in all of the three PE subclasses. Fish oil reduced the AA in the old rat brains, diacyl and alkenylacyl 18:0/20:4 PE being most affected. Phosphatidylcholines gave less pronounced response. Six genes were up-regulated, whereas no significant changes were observed in brains of old rats receiving fish oil for 1 month. None of them except synuclein in young rat brains could be related to mental functions. Old rats on the fish-oil diet did not perform better in Morris water maze test than the control ones. A 10% increase in levels of diacyl 18:0/22:6 PE in young rat brains resulted in a significant improvement of learning capacity. The results are interpreted in terms of the roles of different phospholipid molecular species in cognitive functions coupled with differential responsiveness of the genetic machinery of neurons to n-3 polyunsaturated fatty acids.

Branched-chain Ketoacyl Dehydrogenase Deficiency: Maple Syrup Disease

Classic maple syrup disease can be managed to allow a benign neonatal course, normal growth, and low hospitalization rates. The majority of affected infants that are prospectively managed have good neurodevelopmental outcome; however, acute metabolic intoxication and neurologic deterioration can develop rapidly at any age. Each episode is associated with a risk for cerebral edema, cerebrovascular compromise, and brain herniation. High plasma leucine and, possibly, alpha-ketoisocaproate are the principal neurotoxins in maple syrup disease. Plasma levels rise rapidly in association with net protein catabolism provoked by common infections and injuries. Transient periods of maple syrup disease encephalopathy appear fully reversible, leaving no clinically detectable neurologic sequelae. In contrast, prolonged amino acid imbalance, particularly if occurring during the critical period of brain development, leads to neuronal hypoplasia, a paucity of synapses, and undermyelination. Stagnated maturation and inadequate nutritional maintenance of brain structure have lifelong neurologic and behavioral consequences. Core elements of effective long-term therapy include screening and identification of asymptomatic newborns, frequent plasma amino acid monitoring, careful attention to branched-chain amino acid nurtriture, prevention of cerebral essential amino acid deficiencies, adequate provision of essential omega-3 class fatty acids and micronutrients deficient in commercial formulas, methods for home monitoring of metabolic control, and a commitment to lifelong therapy. Recognizing the risk for acute leucine intoxication depends on anticipating effects of common childhood infection and physiologic stresses on whole body protein turnover. Successful management of metabolic decompensation is based on the use of home sick-day regimens, rapid availability of branched-chain amino acid-free hyperalimentation solutions for hospitalized children, prevention of hyponatremia in patients with leucinosis, and frequent adjustments of intravenous therapies guided by plasma amino acid levels and indices of metabolic and clinical response.

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

Rats were fed from conception till adulthood either with normal rat chow with a linoleic (LA) to linolenic acid (LNA) ratio of 8.2:1 or a rat chow supplemented with a mixture of perilla and soy bean oil giving a ratio of LA to LNA of 4.7:1. Fat content of the feed was 5%. Fatty acid and molecular species composition of ethanolamine phosphoglyceride was determined. Effect of this diet on gene expression was also studied. There was an accumulation of docosahexaenoic (DHA) and arachidonic acids (AA) in brains of the experimental animals. Changes in the ratio sn-1 saturated, sn-2 docosahexaenoic to sn-1 monounsaturated, sn-2 docosahexaenoic were observed. Twenty genes were found overexpressed in response to the 4.7:1 mixture diet and four were found down-regulated compared to normal rat chow. Among them were the genes related to energy household, lipid metabolism and respiration. The degree of up-regulation exceeded that observed with perilla with a ratio of LA to LNA 8.2:1 [Proc. Natl. Acad. Sci. U. S. A. 99 (2002) 2619]. It was concluded that brain sensitively reacts to the fatty acid composition of the diet. It was suggested that alteration in membrane architecture and function coupled with alterations in gene expression profiles may contribute to the observed beneficial impact of n-3 type polyunsaturated fatty acids on cognitive functions.