The nervous system has an absolute molecular species requirement for proper function

Cross-talk between bioactive lipid mediators and the unfolded protein response in ischemic stroke

Ischemic cerebral stroke is a severe medical condition that affects about 15 million people every year and is the second leading cause of death and disability globally. Ischemic stroke results in neuronal cell death and neurological impairment. Current therapies may not adequately address the deleterious metabolic changes and may increase neurological damage. Oxygen and nutrient depletion along with the tissue damage result in endoplasmic reticulum (ER) stress, including the Unfolded Protein Response (UPR), and neuroinflammation in the affected area and cause cell death in the lesion core. The spatio-temporal production of lipid mediators, either pro-inflammatory or pro-resolving, decides the course and outcome of stroke. The modulation of the UPR as well as the resolution of inflammation promotes post-stroke cellular viability and neuroprotection. However, studies about the interplay between the UPR and bioactive lipid mediators remain elusive and this review gives insights about the crosstalk between lipid mediators and the UPR in ischemic stroke. Overall, the treatment of ischemic stroke is often inadequate due to lack of effective drugs, thus, this review will provide novel therapeutical strategies that could promote the functional recovery from ischemic stroke.

Weight Change and Neuropsychiatric Symptoms in Alzheimer's Disease and Frontotemporal Dementia: Associations with Cognitive Decline

Weight changes, neuropsychiatric symptoms (NPS), and cognitive decline often coincide in Alzheimer's disease (AD) and frontotemporal dementia (FTD); however, the direction of their relationship remains unclear. This study aims to clarify the connection between weight changes, NPS, and cognition in AD and FTD. We found that cognitive decline was associated with decreased body mass index (BMI) in AD, while BMI gain was associated with increased conversion to FTD. Elevated NPS were associated with decreased BMI in AD and increased BMI in FTD. Identifying early changes in NPS and BMI may facilitate the detection of cognitive decline, providing an opportunity for early intervention.

Dietary Phospholipid-Bound Conjugated Linoleic Acid and Docosahexaenoic Acid Incorporation Into Fetal Liver and Brain Modulates Fatty Acid and N-Acylethanolamine Profiles

We evaluated whether maternal intake of conjugated linoleic acid (CLA) and docosahexaenoic acid (DHA) in the phospholipid (PL) form (CLA-DHA PL) affects maternal and fetal brain and liver fatty acids (FAs) profile and the biosynthesis of FA-derived bioactive lipid mediators N-acylethanolamines (NAEs) involved in several neurophysiological functions. We fed rat dams during the first 2/3 of their pregnancy a CLA-DHA PL diet containing PL-bound 0.5% CLA and 0.2% DHA. FA and NAE profiles were analyzed in maternal and fetal liver and brain by Liquid Chromatography diode array detector (LC-DAD) and MS/MS in line. We found that CLA and DHA crossed the placenta and were readily incorporated into the fetal liver and brain. CLA metabolites were also found abundantly in fetal tissues. Changes in the FA profile induced by the CLA-DHA PL diet influenced the biosynthesis of NAE derived from arachidonic acid (ARA; N-arachidonoylethanolamine, AEA) and from DHA (N-docosahexaenoylethanolamine, DHEA). The latter has been previously shown to promote synaptogenesis and neuritogenesis. The reduced tissue n6/n3 ratio was associated to a significant decrease of AEA levels in the fetal and maternal liver and an increase of DHEA in the fetal and maternal liver and in the fetal brain. Maternal dietary CLA-DHA PL by promptly modifying fetal brain FA metabolism, and thereby, increasing DHEA, might represent an effective nutritional strategy to promote neurite growth and synaptogenesis and protect the offspring from neurological and psychiatric disorders with neuroinflammatory and neurodegenerative basis during the critical prenatal period.

Late-Life Obesity Associated with Tau Pathology in Cognitively Normal Individuals: The CABLE Study

BACKGROUND

Existed evidence suggests that midlife obesity increases the risk of Alzheimer's disease (AD), while there is an inverse association between AD and obesity in late life. However, the underlying metabolic changes of AD pathological proteins attributed to obesity in two life stages were not clear.

OBJECTIVE

To investigate the associations of obesity types and obesity indices with AD biomarkers in cerebrospinal fluid (CSF) in different life stages.

METHODS

We recruited 1,051 cognitively normal individuals (61.94±10.29 years, 59.66%male) from the Chinese Alzheimer's Biomarker and LifestylE (CABLE) study with CSF detections for amyloid-β 42 (Aβ 42), total-tau (T-tau), and phosphorylated tau (P-tau). We utilized body mass index, waist circumference, waist-to-height ratio, and metabolic risk factors to determine human obesity types. Multiple linear models and interaction analyses were run to assess the impacts of obesity on AD biomarkers.

RESULTS

The metabolically unhealthy obesity or healthy obesity might exert a reduced tau pathology burden (p <  0.05). Individuals with overweight, general obesity, and central obesity presented lower levels of tau-related proteins in CSF than normal controls (p <  0.05). Specially, for late-life individuals, higher levels of obesity indices were associated with a lower load of tau pathology as measured by CSF T-tau and T-tau/Aβ 42 (p <  0.05). No similar significant associations were observed in midlife.

CONCLUSION

Collectively, late-life general and central obesity seems to be associated with the reduced load of tau pathology, which further consolidates the favorable influence of obesity in specific life courses for AD prevention.

On the Structure and Flip-flop of Free Docosahexaenoic Acid in a Model Human Brain Membrane

Among the omega-3 fatty acids, docosahexaenoic acid (DHA, sn22:6) is particularly vital in human brain cell membranes. There is considerable interest in DHA because low-level DHA has been associated with declined cognitive function and poor visual acuity. In this work, atomistic molecular dynamics simulations were used to investigate the effects of free protonated DHA (DHAP) in molar fractions of 0, 17, 30, and 38% in a realistic model of a healthy brain cell membrane comprising 26 lipid types. Numerous flip-flop events of DHAP were observed and categorized as successful or aborted. Novel use of the machine learning technique, density-based spatial clustering of applications with noise (DBSCAN), effectively identified flip-flop events by way of clustering. Our data show that increasing amounts of DHAP in the membrane disorder the bilayer packing, fluidize the membrane, and increase the rates of successful flip-flop from k = 0.2 μs^-1 (17% DHAP) to 0.8 μs^-1 (30% DHAP) and to 1.3 μs^-1 (38% DHAP). In addition, we also provided a detailed understanding of the flip-flop mechanism of DHAP across this complex membrane. Interestingly, we noted the role of hydrogen bonds in two distinct coordinated flip-flop phenomena between two DHAP molecules: double flip-flop and assisted flip-flop. Understanding the effects of various concentrations of DHAP on the dynamics within a lipid membrane and the resulting structural properties of the membrane are important when considering the use of DHAP as a dietary supplement or as a potential therapeutic.

Body mass index trajectories and the risk for Alzheimer's disease among older adults

The effect of body mass index (BMI) changes and variability on the risk for Alzheimer’s disease (AD) remains unclear. We analyzed 45,076 participants, whose BMI were measured on phase 1 (2002–2003), phase 2 (2004–2005), and phase 3 (2006–2007), of the Korean National Health Insurance Service-Health Screening Cohort. We evaluated the effect of 2- and 4-year BMI changes and BMI variability on the risk of AD using Cox regression models. In men, association between 2-year BMI changes, BMI variability, and the risk of AD was not significant. Risk of AD was higher in men whose BMI had decreased 10.1–15.0% over 4 years. In women, aHRs and 95% CIs for AD were 1.14 (1.02–1.29), 1.44 (1.17–1.79), and 1.51 (1.09–2.09) when 2-year BMI loss was 5.1–10.0%, 10.1–15.0%, and > 15.0%. The HRs for AD in women significantly increased when 4-year BMI loss was > 5.0%. The aHR and 95% CI for AD was 1.31 (1.17–1.46) in the 4th quartile of average successive variability (ASV) compared with the 1st quartile of ASV in women. BMI loss over 2- and 4-year period was associated with increased risk for AD, and risk increased in women with higher BMI variability. Appropriate body weight management is recommended to prevent AD.

Conjugated Linoleic Acid and Brain Metabolism: A Possible Anti-Neuroinflammatory Role Mediated by PPARα Activation

Fatty acids play a crucial role in the brain as specific receptor ligands and as precursors of bioactive metabolites. Conjugated linoleic acid (CLA), a group of positional and geometric isomers of linoleic acid (LA, 18:2 n-6) present in meat and dairy products of ruminants and synthesized endogenously in non-ruminants and humans, has been shown to possess different nutritional properties associated with health benefits. Its ability to bind to peroxisome proliferator-activated receptor (PPAR) α, a nuclear receptor key regulator of fatty acid metabolism and inflammatory responses, partly mediates these beneficial effects. CLA is incorporated and metabolized into brain tissue where induces the biosynthesis of endogenous PPARα ligands palmitoylethanolamide (PEA) and oleoylethanolamide (OEA), likely through a positive feedback mechanism where PPARα activation sustains its own cellular effects through ligand biosynthesis. In addition to PPARα, PEA and OEA may as well bind to other receptors such as TRPV1, further extending CLA own anti-neuroinflammatory actions. Future studies are needed to investigate whether dietary CLA may exert anti-inflammatory activity, particularly in the setting of neurodegenerative diseases and neuropsychiatric disorders with a neuroinflammatory basis.

Participation of the nucleus accumbens dopaminergic system in the antidepressant-like actions of a diet rich in omega-3 polyunsaturated fatty acids

The beneficial effects of omega (ω)-3 polyunsaturated fatty acid (PUFA) supplementation on major depressive disorder have been actively studied, but the underlying mechanism remains unknown. The present study examined the involvement of the nucleus accumbens (NAc) dopaminergic systems in behavioral changes in mice fed a diet high in ω-3 PUFAs. Mice fed a diet containing about double the amount of ω-3 PUFAs (krill oil (KO) diet) exerted shorter immobility times in the forced swim test (FST) than mice fed a control diet, containing only α-linolenic acid (ALA) as ω-3 PUFAs. The shorter immobility times were observed in both male and female mice. A dopamine metabolite, 3,4-dihydroxyphenylacetic acid, increased in the NAc in male mice fed the KO diet when compared with those fed the control diet. In addition, dopamine, 3-methoxytyramine, and homovanillic acid increased in the NAc in female mice fed the KO diet. Notably, the effects of the KO diet on the immobility time in the FST were abolished by microinjection of sulpiride, an antagonist of D₂-like receptors, into the NAc. A similar microinjection of an antagonist selective for D₁-like receptors, SKF83566, also abolished the reduction in immobility in the FST. Moreover, we found that tyrosine hydroxylase-positive cells increased in the ventral tegmental area (VTA) in mice fed the KO diet. These results suggest that modulation of the VTA-NAc dopaminergic pathway is one of the mechanisms by which a KO diet rich in ω-3 PUFAs reduces the immobility behavior in the mouse FST.

Maternal fish consumption during pregnancy and smoking behavioural patterns

n-3 Highly unsaturated fatty acids (HUFA), are essential components of neuronal membranes and mediate a range of complex bioactive properties including gene expression, myelination, cell-signalling and dopaminergic function. Deficits in n-3 HUFA have been linked to increased risks for addictive disorders, thus we posited that lower fish consumption would be associated with greater risks for perinatal smoking among 9640 mothers enroled in the Avon Longitudinal Study of Parents and Children. We used univariable and multivariable regression models to examine relationships between self-reported prenatal dietary intakes of n-3 HUFA-rich foods (fish and shellfish) and maternal smoking; outcomes included cessation and the number of cigarettes smoked per d. Both before and during pregnancy, there was consistent evidence (P<0·001) of protective fish intake-smoking associations; relative to mothers reporting no fish consumption, those who reported some fish consumption (<340 g/week) and high fish consumption (340 g+/week) at 32 weeks of gestation showed lower likelihoods of smoking (adjusted P values <0·001). Respective OR for these relationships were 0·87 (95% CI 0·77, 0·97) and 0·73 (95% CI 0·61, 0·86). Although the prevalence of smoking diminished, from a high of 31·6% (pre-pregnancy) to a low of 18·7% (second trimester), the magnitude of fish intake-smoking associations remained stable following adjustment for confounders. These observations suggest that greater fish or n-3 HUFA consumption should be evaluated as an intervention to reduce or prevent smoking in randomised clinical trials.

Vegetarian diets and depressive symptoms among men

BACKGROUND

Vegetarian diets are associate with cardiovascular and other health benefits, but little is known about mental health benefits or risks.

AIMS

To determine whether self-identification of vegetarian dietary habits is associated with significant depressive symptoms in men.

METHOD

Self-report data from 9668 adult male partners of pregnant women in the Avon Longitudinal Study of Parents and Children (ALSPAC) included identification as vegetarian or vegan, dietary frequency data and the Edinburgh Post Natal Depression Scale (EPDS). Continuous and binary outcomes were assessed using multiple linear and logistic regression taking account of potential confounding variables including: age, marital status, employment status, housing tenure, number of children in the household, religion, family history of depression previous childhood psychiatric contact, cigarette and alcohol consumption.

RESULTS

Vegetarians [n = 350 (3.6% of sample)], had higher depression scores on average than non-vegetarians (mean difference 0.96 points [95%CI + 0.53, + 1.40]) and a greater risk for EPDS scores above 10 (adjusted OR = 1.67 [95% CI: 1.14,2.44]) than non-vegetarians after adjustment for potential confounding factors.

CONCLUSIONS

Vegetarian men have more depressive symptoms after adjustment for socio-demographic factors. Nutritional deficiencies (e.g. in cobalamin or iron) are a possible explanation for these findings, however reverse causation cannot be ruled out.

Phospholipase A2-Induced Remodeling Processes on Liquid-Ordered/Liquid-Disordered Membranes Containing Docosahexaenoic or Oleic Acid: A Comparison Study

Vesicle cycling, which is an important biological event, involves the interplay between membrane lipids and proteins, among which the enzyme phospholipase A2 (PLA2) plays a critical role. The capacity of PLA2 to trigger the budding and fission of liquid-ordered (L(o)) domains has been examined in palmitoyl-docosahexaenoylphosphatidylcholine (PDPC) and palmitoyl-oleoylphosphatidylcholine (POPC)/sphingomyelin/cholesterol membranes. They both exhibited a L(o)/liquid-disordered (L(d)) phase separation. We demonstrated that PLA2 was able to trigger budding in PDPC-containing vesicles but not POPC ones. The enzymatic activity, line tension, and elasticity of the membrane surrounding the L(o) domains are critical for budding. The higher line tension of Lo domains in PDPC mixtures was assigned to the greater difference in order parameters of the coexisting phases. The higher amount of lysophosphatidylcholine generated by PLA2 in the PDPC-containing mixtures led to a less-rigid membrane, compared to POPC. The more elastic L(d) membranes in PDPC mixtures exert a lower counteracting force against the L(o) domain bending.

Toward therapeutic targets for SCA3: Insight into the role of Machado-Joseph disease protein ataxin-3 in misfolded proteins clearance

Machado-Joseph disease (MJD, also known as spinocerebellar ataxia type 3, SCA3), an autosomal dominant neurological disorder, is caused by an abnormal expanded polyglutamine (polyQ) repeat in the ataxin-3 protein. The length of the expanded polyQ stretch correlates positively with the severity of the disease and inversely with the age at onset. To date, we cannot fully explain the mechanism underlying neurobiological abnormalities of this disease. Yet, accumulating reports have demonstrated the functions of ataxin-3 protein in the chaperone system, ubiquitin-proteasome system, and aggregation-autophagy, all of which suggest a role of ataxin-3 in the clearance of misfolded proteins. Notably, the SCA3 pathogenic form of ataxin-3 (ataxin-3(exp)) impairs the misfolded protein clearance via mechanisms that are either dependent or independent of its deubiquitinase (DUB) activity, resulting in the accumulation of misfolded proteins and the progressive loss of neurons in SCA3. Some drugs, which have been used as activators/inducers in the chaperone system, ubiquitin-proteasome system, and aggregation-autophagy, have been demonstrated to be efficacious in the relief of neurodegeneration diseases like Huntington's disease (HD), Parkinson's (PD), Alzheimer's (AD) as well as SCA3 in animal models and clinical trials, putting misfolded protein clearance on the list of potential therapeutic targets. Here, we undertake a comprehensive review of the progress in understanding the physiological functions of ataxin-3 in misfolded protein clearance and how the polyQ expansion impairs misfolded protein clearance. We then detail the preclinical studies targeting the elimination of misfolded proteins for SCA3 treatment. We close with future considerations for translating these pre-clinical results into therapies for SCA3 patients.

Modulation of fear memory by dietary polyunsaturated fatty acids via cannabinoid receptors

Although the underlying mechanism remains unknown, several studies have suggested benefits of n-3 long-chain polyunsaturated fatty acid (PUFA) for patients with anxiety disorders. Elevated fear is thought to contribute to the pathogenesis of particular anxiety disorders. The aim of the present study was to evaluate whether the dietary n-3 to n-6 PUFA (3:6) ratio influences fear memory. For this purpose, the effects of various dietary 3:6 ratios on fear memory were examined in mice using contextual fear conditioning, and the effects of these diets on central synaptic transmission were examined to elucidate the mechanism of action of PUFA. We found that fear memory correlated negatively with dietary, serum, and brain 3:6 ratios in mice. The low fear memory in mice fed a high 3:6 ratio diet was increased by the cannabinoid CB1 receptor antagonist rimonabant, reaching a level seen in mice fed a low 3:6 ratio diet. The agonist sensitivity of CB1 receptor was enhanced in the basolateral nucleus of the amygdala (BLA) of mice fed a high 3:6 ratio diet, compared with that of mice fed a low 3:6 ratio diet. Similar enhancement was induced by pharmacological expulsion of cholesterol in the neuronal membrane of brain slices from mice fed a low 3:6 ratio diet. CB1 receptor-mediated short-term synaptic plasticity was facilitated in pyramidal neurons of the BLA in mice fed a high 3:6 ratio diet. These results suggest that the ratio of n-3 to n-6 PUFA is a factor regulating fear memory via cannabinoid CB1 receptors.

Conversion of α-linolenic acid to long-chain omega-3 fatty acid derivatives and alterations of HDL density subfractions and plasma lipids with dietary polyunsaturated fatty acids in Monk parrots (Myiopsitta monachus)

The effect of α-linolenic acid from a flaxseed (FLX)-enriched diet on plasma lipid and fatty acid metabolism and possible atherosclerosis risk factors was studied in Monk parrots (Myiopsitta monachus). Twenty-four Monk parrots were randomly assigned to diets containing either 10% ground SUNs or 10% ground FLXs. Feed intake was calculated daily. Blood samples, body condition scores and body weights were obtained at -5 weeks, day 0, 7, 14, 28, 42 and 70. Plasma samples were analysed for total cholesterol, free cholesterol, triacylglycerols and lipoproteins. Phospholipid subfraction fatty acid profiles were determined. By day 70, the FLX group had significantly higher plasma phospholipid fatty acids including 18:3n-3 (α-linolenic acid), 20:5n-3 (eicosapentaenoic acid) and 22:6n-3 (docosahexaenoic acid). The sunflower group had significantly higher plasma phospholipid levels of 20:4n-6 (arachidonic acid). By day 70, the high-density lipoprotein (HDL) peak shifted resulting in significantly different HDL peak densities between the two experimental groups (1.097 g/ml FLX group and 1.095 g/ml SUN group, p = 0.028). The plasma fatty acid results indicate that Monk parrots can readily convert α-linolenic acid to the long-chain omega-3 derivatives including docosahexaenoic acid and reduce 20:4n-6 accumulation in plasma phospholipids. The reason for a shift in the HDL peak density is unknown at this time.

Umbilical cord PUFA are determined by maternal and child fatty acid desaturase (FADS) genetic variants in the Avon Longitudinal Study of Parents and Children (ALSPAC)

Fetal supply with long-chain PUFA (LC-PUFA) during pregnancy is important for brain growth and visual and cognitive development and is provided by materno-fetal placental transfer. We recently showed that maternal fatty acid desaturase (FADS) genotypes modulate the amounts of LC-PUFA in maternal blood. Whether FADS genotypes influence the amounts of umbilical cord fatty acids has not been investigated until now. The aim of the present study was to investigate the influence of maternal and child FADS genotypes on the amounts of LC-PUFA in umbilical cord venous plasma as an indicator of fetal fatty acid supply during pregnancy. A total of eleven cord plasma n-6 and n-3 fatty acids were analysed for association with seventeen FADS gene cluster SNP in over 2000 mothers and children from the Avon Longitudinal Study of Parents and Children. In a multivariable analysis, the maternal genotype effect was adjusted for the child genotype and vice versa to estimate which of the two has the stronger influence on cord plasma fatty acids. Both maternal and child FADS genotypes and haplotypes influenced amounts of cord plasma LC-PUFA and fatty acid ratios. Specifically, most analysed maternal SNP were associated with cord plasma levels of the precursor n-6 PUFA, whereas the child genotypes were mainly associated with more highly desaturated n-6 LC-PUFA. This first study on FADS genotypes and cord fatty acids suggests that fetal LC-PUFA status is determined to some extent by fetal fatty acid conversion. Associations of particular haplotypes suggest specific effects of SNP rs498793 and rs968567 on fatty acid metabolism.

Weight loss and Alzheimer's disease: temporal and aetiologic connections

The intermediate and advanced stages of Alzheimer's disease (AD) are frequently associated with weight loss (WL), but WL may even precede the onset of cognitive symptoms. This review focuses on the possible aetiologic and temporal relationships between AD and WL. When WL occurs some years before any signs of cognitive impairment, it may be a risk factor for dementia due to deficiency of several micronutrients, such as vitamins and essential fatty acids, and consequent oxidative tissue damage. The leptin reduction associated with WL may also facilitate cognitive decline. The mechanisms potentially inducing WL in AD include lower energy intake, higher resting energy expenditure, exaggerated physical activity, or combinations of these factors. A hypermetabolic state has been observed in animals with AD, but has not been confirmed in human subjects. This latter mechanism could involve amyloid assemblies that apparently increase the circulating cytokine levels and proton leakage in mitochondria. WL may be caused by patients’ increased physical activity as they develop abnormal motor behaviour (restlessness and agitation) and waste energy while trying to perform daily activities. During the course of AD, patients usually find it increasingly difficult to eat, so they ingest less food. AD-related neurodegeneration also affects brain regions involved in regulating appetite. The caregiver has an important role in ensuring an adequate food intake and controlling behavioural disturbances. In conclusion, WL is closely linked to AD, making periodic nutritional assessments and appropriate dietary measures important aspects of an AD patient's treatment.

Serum fatty acid profile in subjects with irritable bowel syndrome

OBJECTIVE

Irritable bowel syndrome (IBS) is a fluctuating disorder of the gastrointestinal tract, characterized by abdominal pain and change in bowel habit. We wanted to investigate subjects with IBS for signs of disturbed intestinal absorption of fatty acids, as reflected in serum composition.

MATERIAL AND METHODS

Serum samples were obtained from 32 adults with IBS, and from 59 controls. Serum fatty acids were analyzed by capillary gas-liquid chromatography.

RESULTS

Especially the proportions of arachidonic acid (20:4 n-6) and the long-chain polyunsaturated fatty acids of the n-3 family docosapentaenoic acid (22:5 n-3) and docosahexaenoic acid (22:6 n-3) were decreased in subjects with IBS. The proportions of unsaturated and monounsaturated fatty acids were generally increased in IBS compared to controls.

CONCLUSIONS

Although organic disease has been ruled out in patients with IBS, they presented signs of inadequate supply of long-chain fatty acids. Supplementation with n-3 fatty acids may be implicated.

Conjugated double bonds in lipid bilayers: a molecular dynamics simulation study

Conjugated linoleic acids (CLA) are found naturally in dairy products. Two isomers of CLA, that differ only in the location of cis and trans double bonds, are found to have distinct and different biological effects. The cis 9 trans 11 (C9T11) isomer is attributed to have the anti-carcinogenic effects, while the trans 10 cis 12 (T10C12) isomer is believed to be responsible for the anti-obesity effects. Since dietary CLA are incorporated into membrane phospholipids, we have used Molecular Dynamics (MD) simulations to investigate the comparative effects of the two isomers on lipid bilayer structure. Specifically, simulations of phosphatidylcholine lipid bilayers in which the sn-2 chains contained one of the two isomers of CLA were performed. Force field parameters for the torsional potential of double bonds were obtained from ab initio calculations. From the MD trajectories we calculated and compared structural properties of the two lipid bilayers, including areas per molecule, density profiles, thickness of bilayers, tilt angle of tail chains, order parameters profiles, radial distribution function (RDF) and lateral pressure profiles. The main differences found between bilayers of the two CLA isomers, are (1) the order parameter profile for C9T11 has a dip in the middle of sn-2 chain while the profile for T10C12 has a deeper dip close to terminal of sn-2 chain, and (2) the lateral pressure profiles show differences between the two isomers. Our simulation results reveal localized physical structural differences between bilayers of the two CLA isomers that may contribute to different biological effects through differential interactions with membrane proteins or cholesterol.

Effect of sex and dietary fat intake on the fatty acid composition of phospholipids and triacylglycerol in rat heart

Variations in the fatty acid composition of lipids in the heart alter its function and susceptibility to ischaemic injury. We investigated the effect of sex and dietary fat intake on the fatty acid composition of phospholipids and triacylglycerol in rat heart. Rats were fed either 40 or 100g/kg fat (9:1 lard:soybean oil) from weaning until day 105. There were significant interactive effects of sex and fat intake on the proportions of fatty acids in heart phospholipids, dependent on phospholipid classes. 20:4n-6, but not 22:6n-3, was higher in phospholipids in females than males fed a low, but not a high, fat diet. There was no effect of sex on the composition of triacylglycerol. These findings suggest that sex is an important factor in determining the incorporation of dietary fatty acids into cardiac lipids. This may have implications for sex differences in susceptibility to heart disease.

The Δ4-desaturation pathway for DHA biosynthesis is operative in the human species: differences between normal controls and children with the Zellweger syndrome

Background

Docosahexaenoic acid (DHA, 22:6ω3) is a fundamental component of cell membranes, especially in the brain and retina. In the experimental animal, DHA deficiency leads to suboptimal neurological performance and visual deficiencies. Children with the Zellweger syndrome (ZS) have a profound DHA deficiency and symptoms that can be attributed to their extremely low DHA levels. These children seem to have a metabolic defect in DHA biosynthesis, which has never been totally elucidated. Treatment with DHA ethyl ester greatly improves these patients, but if we could normalize their endogenous DHA production we could get additional benefits. We examined whether DHA biosynthesis by Δ4-desaturation could be enhanced in the human species by transfecting the enzyme, and if this could normalize the DHA levels in cells from ZS patients.

Results

We showed that the Δ4-desaturase gene (Fad4) from Thraustochytrium sp, which can be expressed by heterologous transfection in other plant and yeast cells, can also be transfected into human lymphocytes, and that it expresses the enzyme (FAD4, Δ4-desaturase) by producing DHA from direct Δ4-desaturation of 22:5ω3. We also found that the other substrate for Δ4-desaturase, 22:4ω6, was parallely desaturated to 22:5ω6.

Conclusions

The present "in vitro" study demonstrates that Δ4-desaturase can be transfected into human cells and synthesize DHA (as well as 22:5ω6, DPA) from 22:5ω3 and 22:4ω6, respectively, by putative Δ4-desaturation. Even if this pathway may not be the physiological route for DHA biosynthesis "in vivo", the present study opens new perspectives for the treatment of patients within the ZS spectrum.

Serum fatty acid profile in celiac disease patients before and after a gluten-free diet

OBJECTIVE

Celiac disease (CD) is characterized by villous atrophy with crypt hyperplasia and inflammation of the small intestinal mucosa leading to disturbed epithelial transport. In untreated CD, fat malabsorption can occur. The aim of this study was to investigate the profile of serum fatty acids in newly detected CD before and after treatment with a gluten-free diet.

MATERIAL AND METHODS

Serum samples were obtained from 50 adults with active CD showing small-bowel mucosal villous atrophy, from the same patients in remission after treatment with a gluten-free diet, and from 59 controls. Serum fatty acids were analyzed by capillary gas-liquid chromatography.

RESULTS

Especially the proportions of arachidonic acid (20:4 n-6) and the long-chain polyunsaturated fatty acids of the n-3 family docosapentaenoic acid (22:5 n-3) and docosahexaenoic acid (22:6 n-3) were decreased in subjects with active CD. Serum levels of these fatty acids increased during remission, but still remained significantly lower than control values. Levels of unsaturated and monounsaturated fatty acids were generally increased in subjects with CD compared with those in controls.

CONCLUSIONS

In patients with CD, determination of serum fatty acid composition can be considered if the dietary history or symptoms suggest an inadequate supply of long-chain fatty acids.

n-3, but not n-6 lipid particle uptake requires cell surface anchoring

Omega-3 (n-3) fatty acids are emerging as bioactive agents protective against cardiovascular disease. However, their cellular delivery pathways are poorly defined. Here we questioned whether the uptake of n-3 triglyceride-rich particles (TGRP) is mediated by cell surface proteoglycans (PG) using LDL receptor (LDLR)+/+ and LDLR-/- cell models. LDLR+/+ but not LDLR-/- cells showed higher n-6 over n-3 TGRP uptake. Removal of cell surface proteins and receptors by pronase markedly enhanced the uptake of n-3 but not n-6 TGRP. Lactoferrin blockage of apoE-mediated pathways decreased the uptake of n-6 TGRP by up to 85% (p<0.05) but had insignificant effect on n-3 TGRP uptake. PG removal by sodium chlorate in LDLR+/+ cells substantially reduced n-3 TGRP uptake but had little effect on n-6 TGRP uptake. Thus, while n-6 TGRP uptake is preferentially mediated by LDLR-dependent pathways, the uptake of n-3 TGRP depends more on PG and non-LDLR cell surface anchoring.

Considerations regarding neuropsychiatric nutritional requirements for intakes of omega-3 highly unsaturated fatty acids

BACKGROUND

Adverse neurodevelopmental and neuropsychiatric outcomes have been established as signs of nutrient deficiencies and may be applicable to insufficient dietary intakes of omega-3 highly unsaturated fatty acids (n-3 HUFAs).

OBJECTIVE

Consider if statistical definitions for Daily Reference Intakes can be applied to n-3 HUFAs intakes during pregnancy for maternal and neurodevelopmental deficiencies.

DESIGN

Data were prospectively collected from women during pregnancy and children up to age 8 years participating in the Avon Longitudinal Study of Parents and Children (ALSPAC). Statistical analyses took social and lifestyle factors into account.

RESULTS

During pregnancy, n-3 HUFA intakes from seafood that putatively meet statistical definitions of an estimated average requirement ranged from 0.05 to 0.06 en% (111-139 mg/d/2000 Cal) for suboptimal fine motor control at 42 m and 0.065-0.08 en% (114-181 mg/d/2000 Cal) for suboptimal verbal IQ at age 8 years and 0.18-0.22 en% (389-486 mg/d/2000 Cal) for maternal depression at 32 weeks. Intakes of n-3 ranging from 0.2 to 0.41 en% (445-917 mg/d/2000 Cal) prevented both increased risk of maternal depression and adverse neurodevelopmental outcomes for children among 97.5% of the population. No upper limit for safety was found.

CONCLUSION

During pregnancy, a n-3 HUFA intake of 0.40 en% (900 mg/d/2000 Cal) from seafood is likely to meet the nutritional requirements for 97.5% of the mothers and children of this population. These considerations do not constitute DRI's for docosahexaenoic acid and n-3 HUFAs, but may contribute to their formulation.

Uncoupling of interleukin-6 from its signalling pathway by dietary n-3-polyunsaturated fatty acid deprivation alters sickness behaviour in mice

Sickness behaviour is an adaptive behavioural response to the activation of the innate immune system. It is mediated by brain cytokine production and action, especially interleukin-6 (IL-6). Polyunsaturated fatty acids (PUFA) are essential fatty acids that are highly incorporated in brain cell membranes and display immunomodulating properties. We hypothesized that a decrease in n-3 (also known as omega3) PUFA brain level by dietary means impacts on lipopolysaccharide (LPS)-induced IL-6 production and sickness behaviour. Our results show that mice exposed throughout life to a diet containing n-3 PUFA (n-3/n-6 diet) display a decrease in social interaction that does not occur in mice submitted to a diet devoid of n-3 PUFA (n-6 diet). LPS induced high IL-6 plasma levels as well as expression of IL-6 mRNA in the hippocampus and cFos mRNA in the brainstem of mice fed either diet, indicating intact immune-to-brain communication. However, STAT3 and STAT1 activation, a hallmark of the IL-6 signalling pathway, was lower in the hippocampus of LPS-treated n-6 mice than n-3/n-6 mice. In addition, LPS did not reduce social interaction in IL-6-knockout (IL-6-KO) mice and failed to induce STAT3 activation in the brain of IL-6-KO mice. Altogether, these findings point to alteration in brain STAT3 as a key mechanism for the lack of effect of LPS on social interaction in mice fed with the n-6 PUFA diet. The relative deficiency of Western diets in n-3 PUFA could impact on behavioural aspects of the host response to infection.

Methotrexate-induced alterations in beta-oxidation correlate with cognitive abilities in children with acute lymphoblastic leukemia

Treatment advances, including central nervous system (CNS) treatment with methotrexate, have led to significant gains in disease-free survival from childhood acute lymphoblastic leukemia (ALL). However, methotrexate has been associated with neurological problems such as declines in cognitive and academic abilities. The purpose of this study was to investigate methotrexate-induced changes in beta-oxidation in children with ALL receiving methotrexate for CNS treatment. Specific aims were to investigate effects of methotrexate on beta-oxidation of the two most prevalent fatty acids (palmitic acid and stearic acid) in cerebrospinal fluid (CSF) samples and correlate the ratio of monounsaturation to saturation of these fatty acids with cognitive and academic abilities. The sample included 12 females and 14 males with low-risk (n = 7), standard-risk ( n = 13), or high-risk (n = 6) ALL. Mean age at diagnosis was 94.1 months (SD = 34.4). CSF samples were obtained in conjunction with diagnostic lumbar punctures; subsequent samples were obtained prior to intrathecal methotrexate administration during the induction, consolidation, and continuation phases of treatment. Fatty acids were analyzed by gas chromatography. Results showed a significant increase in the ratio of monounsaturation to saturation of both fatty acids, which was greatest during the most intensive phase of treatment. Ratios of monounsaturated to saturated fatty acids were negatively correlated with full-scale IQ, verbal IQ, and math calculations. Findings suggest that methotrexate alters beta-oxidation and that the resulting increase in fatty acid monounsaturation is related to declines in some domains of cognitive ability.

Seasonal acclimatization of brain lipidome in a eurythermal fish (Carassius carassius) is mainly determined by temperature

Crucian carp ( Carassius carassius) is an excellent vertebrate model for studies on temperature adaptation in biological excitable membranes, since the species can tolerate temperatures from 0 to +36°C. To determine how temperature affects the lipid composition of brain, the fish were acclimated for 4 wk at +30, +16, or +4°C in the laboratory, or seasonally acclimatized individuals were captured from the wild throughout the year (temperature = +1 to +23°C), and the brain glycerophospholipid and sphingolipid compositions were analyzed in detail by electrospray-ionization mass spectrometry. Numerous significant temperature-related changes were found in the molecular species composition of the membrane lipids. The most notable and novel finding was a large (∼3-fold) increase of the di-22:6n-3 phosphatidylserine and phosphatidylethanolamine species in the cold. Since the increase of 22:6n-3 in the total fatty acyl pool of the brain was small, the formation of di-22:6n-3 aminophospholipid species appears to be a specific adaptation to low temperature. Such highly unsaturated species could be needed to maintain adequate membrane fluidity in the vicinity of transporters and other integral membrane proteins. Plasmalogens increased somewhat at higher temperatures, possibly to protect membranes against oxidation. The modifications of brain lipidome during the 4-wk laboratory acclimation were, in many respects, similar to those found in the wild, which indicates that the seasonal changes observed in the wild are temperature dependent rather than induced by other environmental factors.

Docosahexaenoic acid domains: the ultimate non-raft membrane domain

What distinguishes polyunsaturated fatty acids (PUFAs) from less unsaturated fatty acids is the presence of a repeating =CH-CH(2)-CH= unit that produces an extremely flexible structure rapidly isomerizing through conformational states. Docosahexaenoic acid (DHA) with 6 double bonds is the most extreme example. The focus of this review is the profound impact that the high disorder of DHA has on its interaction with cholesterol when the PUFA is incorporated into membrane phospholipids. Results from a battery of biophysical techniques are described. They demonstrate an aversion of DHA for the sterol that drives the lateral segregation of DHA-containing phospholipids into liquid disordered (l(d)) domains that are depleted in cholesterol. These domains are compositionally and organizationally the antithesis of lipid rafts, the much-studied liquid ordered (l(o)) domain that is enriched in predominantly saturated sphingolipids and cholesterol. We hypothesize that the introduction of DHA-rich domains into the plasma membrane where they coexist with lipid rafts is the origin, in part, of the astonishing diversity of health benefits that accrue from dietary consumption of DHA. According to our model, changes in the conformation of signaling proteins when they move between these disparate domains have the potential to modulate cell function.

Sex, but not maternal protein or folic acid intake, determines the fatty acid composition of hepatic phospholipids, but not of triacylglycerol, in adult rats

The aim of the study was to investigate whether the protein and folic acid content of the maternal diet and the sex of the offspring alter the polyunsaturated fatty acid content of hepatic phospholipids and triacylglycerol (TAG). Pregnant rats were fed diets containing 18% or 9% protein with either 1 or 5mg/kg folic acid. Maternal diet did not alter hepatic lipid composition in the adult offspring. Data from each maternal dietary group were combined and reanalysed. The proportion of 18:0, 20:4n-6 and 22:6n-3 in liver phospholipids was higher in females than in males, while hepatic TAG composition did not differ between sexes. Delta5 Desaturase expression was higher in females than in males. Neither Delta5 nor Delta6 desaturase expression was related to polyunsaturated fatty acid concentrations. These results suggest that sex differences in liver phospholipid fatty acid composition may reflect primary differences in the specificity of phospholipid biosynthesis.

Probing phospholipid dynamics by electrospray ionisation mass spectrometry

Recent advances in electrospray ionisation mass spectrometry (ESI-MS) have greatly facilitated the analysis of phospholipid molecular species in a growing diversity of biological and clinical settings. The combination of ESI-MS and metabolic labelling employing substrates labelled with stable isotopes is especially exciting, permitting studies of phospholipid synthesis and turnover in vivo. This review will first describe the methodology involved and will then detail dynamic lipidomic studies that have applied the stable isotope incorporation approach. Finally, it will summarise the increasing number of studies that have used ESI-MS to characterise structural and signalling phospholipid molecular species in development and disease.

Omega-3 fatty acids and rodent behavior

This paper reviews the role of the n-3 fatty acids in the regulation of cognitive functions, locomotor and exploratory activity and emotional status in rodents. There are disparate data on the performance of n-3 fatty acid deficient animals in the open field test and elevated plus maze. Results obtained in our laboratory indicated slower habituation to the open field in deficient mice, which affects total locomotor and exploratory parameters. We also observed no change in plus maze performance of deficient mice under low-stress but elevated anxiety under high-stress conditions. There is some evidence of elevated aggression and increased immobility time in the forced swimming test caused by n-3 fatty acid deficiency in rodents. Effects of n-3 fatty acid deficiency and supplementation on learning in several tests such as the Morris water maze, two odor olfactory discriminations, radial arm maze performance and avoidance tasks are reviewed in detail. There is some evidence of an enhanced vulnerability to stress of n-3 fatty acid deficient animals and this factor can influence performance in a variety of tests. Thus, behavioral tasks that involve a higher level of stress may better differentiate behavioral effects related to brain docosahexaenoic acid (DHA) status. It is suggested that a fruitful area for future investigations of functional alterations related to brain DHA status will be the delineation of the factors underlying changes in performance in behavioral tasks. The possible role of non-cognitive factors like emotionality and attention in the impaired performance of n-3 fatty acid deficient animals also requires further investigation.

Polyunsaturated fatty acid supplementation stimulates differentiation of oligodendroglia cells

Dietary polyunsaturated fatty acids (PUFAs) have been postulated as alternative supportive treatment for multiple sclerosis, since they may promote myelin repair. We set out to study the effect of supplementation with n-3 and n-6 PUFAs on OLN-93 oligodendroglia and rat primary oligodendrocyte differentiation in vitro. It appeared that OLN-93 cells actively incorporate and metabolise the supplemented PUFAs in their cell membrane. The effect of PUFAs on OLN-93 differentiation was further assessed by morphological and Western blot evaluation of markers of oligodendroglia differentiation: 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP), zonula occludens-1 (ZO-1) and myelin-associated glycoprotein (MAG). Supplementation of the OLN-93 cells with n-3 and n-6 PUFAs increased the degree of differentiation determined by morphological analysis. Moreover, CNP protein expression was significantly increased by gamma-linolenic acid (GLA, 18:3n-6) supplementation. In accordance with the OLN-93 results, studies with rat primary oligodendrocytes, a more advanced model of cell differentiation, showed GLA supplementation to promote oligodendrocyte differentiation. Following GLA supplementation, increased numbers of proteolipid protein (PLP)-positive oligodendrocytes and increased myelin sheet formation was observed during differentiation of primary oligodendrocytes. Moreover, increased CNP, and enhanced PLP and myelin basic protein expression were found after GLA administration. These studies provide support for the dietary supplementation of specific PUFAs to support oligodendrocyte differentiation and function.

A diet enriched with the omega-3 fatty acid docosahexaenoic acid reduces amyloid burden in an aged Alzheimer mouse model

Epidemiological studies suggest that increased intake of the omega-3 (n-3) polyunsaturated fatty acid (PUFA) docosahexaenoic acid (DHA) is associated with reduced risk of Alzheimer's disease (AD). DHA levels are lower in serum and brains of AD patients, which could result from low dietary intake and/or PUFA oxidation. Because effects of DHA on Alzheimer pathogenesis, particularly on amyloidosis, are unknown, we used the APPsw (Tg2576) transgenic mouse model to evaluate the impact of dietary DHA on amyloid precursor protein (APP) processing and amyloid burden. Aged animals (17-19 months old) were placed in one of three groups until 22.5 months of age: control (0.09% DHA), low-DHA (0%), or high-DHA (0.6%) chow. beta-Amyloid (Abeta) ELISA of the detergent-insoluble extract of cortical homogenates showed that DHA-enriched diets significantly reduced total Abeta by >70% when compared with low-DHA or control chow diets. Dietary DHA also decreased Abeta42 levels below those seen with control chow. Image analysis of brain sections with an antibody against Abeta (amino acids 1-13) revealed that overall plaque burden was significantly reduced by 40.3%, with the largest reductions (40-50%) in the hippocampus and parietal cortex. DHA modulated APP processing by decreasing both alpha- and beta-APP C-terminal fragment products and full-length APP. BACE1 (beta-secretase activity of the beta-site APP-cleaving enzyme), ApoE (apolipoprotein E), and transthyretin gene expression were unchanged with the high-DHA diet. Together, these results suggest that dietary DHA could be protective against beta-amyloid production, accumulation, and potential downstream toxicity.

Translocation of Ethanolamine Phosphoglyceride is Required for Initiation of Apoptotic Death in OLN-93 Oligodendroglial Cells

The possible interplay between extracellular signal-regulated protein kinase (ERK) activation and ethanolamine phosphoglycerides (PG) membrane bilayer translocation following oxidative stress (OS) (0.5 mM H2O2/0.05 mM Fe2+), was examined in oligodendroglia, OLN93, cells with altered plasma membrane PG composition. Cells supplemented with 50 microM docosahexaenoic acid (DHA, 22:6n3) to increase the number of potential double bond targets for OS in ethanolamine-PG (EPG) were compared to cells with diminished content of EPG, attained by the addition of 0.5 mM N,N-dimethylethanolamine (dEa). After 30 min OS, EPG translocation accompanied by sustained ERK activation and nuclear translocation culminating in apoptosis was found in DHA-supplemented cells in contrast to no EPG translocation, a brief ERK activation, but no nuclear translocation, and no cell death in DHA/dEa-supplemented cells. DHA/dEa-supplemented cells pretreated with the protein-tyrosine phosphatases inhibitor Na3VO4 followed by OS, although expressing a sustained ERK activation and nuclear translocation, failed to show apoptosis and lacked EPG translocation. In DHA-supplemented cells U0126, a MEK inhibitor, prevented ERK activation and EPG translocation and protected from cell death. These findings most likely indicate that ERK activation is an indispensable component for the signaling cascades leading to EPG translocation but only activation of the latter is leading to OS-induced apoptotic cell death.

Maternal dietary 22 : 6n-3 is more effective than 18 : 3n-3 in increasing the 22 : 6n-3 content in phospholipids of glial cells from neonatal rat brain

One of the debates in infant nutrition concerns whether dietary 18 : 3n-3 (linolenic acid) can provide for the accretion of 22 : 6n-3 (docosahexaenoic acid, DHA) in neonatal tissues. The objective of the present study was to determine whether low or high 18 : 3n-3 v. preformed 22 : 6n-3 in the maternal diet enabled a similar 22 : 6n-3 content in the phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI) and phosphatidylserine (PS) of glial cells from whole brain (cerebrum and cerebellum) of 2-week-old rat pups. At parturition, the dams were fed semi-purified diets containing either increasing amounts of 18 : 3n-3 (18 : 2n-6 to 18 : 3n-3 fatty acid ratio of 7.8 : 1, 4.4 : 1 or 1 : 1), preformed DHA, or preformed 20 : 4n-6 (arachidonic acid)+DHA. During the first 2 weeks of life, the rat pups from the respective dams received only their dam's milk. The fatty acid composition of the pups' stomach contents (dam's milk) and phospholipids from glial cells were quantified. The 20 : 4n-6 and 22 : 6n-3 content in the stomach from rat pups at 2 weeks of age reflected the fatty acid composition of the dam's diet. The 20 : 4n-6 content of PE and PS in the glial cells was unaffected by maternal diet treatments. Preformed 22 : 6n-3 in the maternal diet increased the 22 : 6n-3 content of glial cell PE and PS compared with maternal diets providing an 18 : 2n-6 to 18 : 3 n-3 fatty acid ratio of 7.8 : 1, 4.4 : 1 or 1 : 1 (P<0.0001). There was no significant difference in the 20 : 4n-6 and 22 : 6n-3 content of glial cell PC and PI among maternal diet treatments. It was concluded that maternal dietary 22 : 6n-3 is more effective than low or high levels of maternal dietary 18 : 3n-3 at increasing the 22 : 6n-3 content in PE and PS of glial cells from the whole brain of rat pups at 2 weeks of age. The findings from the present study have important implications for human infants fed infant formulas that are devoid of 22 : 6n-3.

Effects of docosahexaenoic acid on the survival and neurite outgrowth of rat cortical neurons in primary cultures

Effects of docosahexaenoic acid (DHA) on survival and neurite outgrowth were investigated in primary cultures of rat cortical neurons. Cell cultures were prepared from cortex on embryonic day 18 (E-18) for treatment with a series of DHA concentrations (12.5, 25, 50, 75, 100 and 200 microM). Docosahexaenoic acid (25-50 microM) significantly enhanced neuronal viability, but lower concentration of DHA (12.5 microM) did not show an obvious effect. In contrast, higher concentrations of DHA (100-200 microM) exerted the significant opposite effects by decreasing neuronal viability. Furthermore, treatment with 25 microM DHA significantly prevented the neurons from death after different culture days in vitro (DIV). Moreover, measurements from the cultures exposed to 25 microM DHA immediately after plating showed significant increases in the percentage of cells with neurites, the mean number of neurite branches, the total neuritic length per cell and the length of the longest neurite in each cell after 24 and 48 h in vitro (HIV). The DHA-treated neurons had greater growth-associated protein-43 (GAP-43) immunoactivity and higher phosphatidylserine (PS) and phosphatidylethanolamine (PE) contents, but lower phosphatidylcholine (PC) content than control neurons. The significant increased DHA contents were also observed in both PE and PS in the treated neurons. These findings suggest that optimal DHA (25 microM) may have positive effects on the survival and the neurite outgrowth of the cultured fetal rat cortical neurons, and the effects probably are related to DHA-stimulating neuron-specific protein synthesis and its enhancing the discrete phospholipid (PL) content through enrichment of DHA in the PL species.

Omega-3 fatty acids: molecular approaches to optimal biological outcomes

PURPOSE OF REVIEW

This review discusses recent advances in delineating basic mechanisms underlying the beneficial effects of omega-3 fatty acids on health and on disease.

RECENT FINDINGS

While a substantial number of studies have delineated many differences between the biological effects of saturated versus polyunsaturated fatty acids, less is known about the long-chain omega-3 fatty acids commonly present in certain fish oils. In this review, we focus on recent studies relating to basic mechanisms whereby omega-3 fatty acids modulate cellular pathways to exert beneficial effects on promoting health and decreasing risks of certain diseases. We will use, as examples, conditions of the cardiovascular, neurological, and immunological systems as well as diabetes and cancer, and then discuss basic regulatory pathways.

SUMMARY

Omega-3 fatty acids are major regulators of multiple molecular pathways, altering many areas of cellular and organ function, metabolism and gene expression. Generally, these regulatory events lead to "positive" endpoints relating to health and disease.

Increasing homicide rates and linoleic acid consumption among five western countries, 1961–2000

Clinical intervention trials and animal studies indicate that increasing dietary intakes of long chain n-3 FA or reducing linoleic acid intake may reduce aggressive and violent behaviors. Here we examine if economic measures of greater n-6 consumption across time and countries correlate with greater risk of homicide. Linoleic acid available for human consumption was calculated from World Health Organization disappearance data for 12 major seed oils in the food supply for the years 1961 to 2000 in Argentina, Australia, Canada, the United Kingdom, and the United States (US). Homicide mortality rates, adjusted for age, were obtained from the central judicial authority of each country. Apparent linoleic acid intake from seed oil sources ranged from 0.29 en% (percentage of daily food energy) (Australia 1962) to 8.3 en% (US 1990s). Greater apparent consumption of linoleic acid correlated with higher rates of homicide mortality over a 20-fold range (0.51-10.2/100,000) across countries and time in an exponential growth regression model (r = 0.94, F = 567, P < 0.00001). Within each country, correlations between greater linoleic acid disappearance and homicide mortality over time were significant in linear regression models. Randomized controlled trials are needed to determine if reducing high intakes of linoleic acid by seed oils with alternative compositions can reduce the risk of violent behaviors. These dietary interventions merit exploration as relatively cost-effective measures for reducing the pandemic of violence in Western societies, just as dietary interventions are reducing cardiovascular mortality. Low linoleate diets may prevent behavioral maladies that correctional institutions, social service programs, and mental health providers intend to treat.

Half-lives of docosahexaenoic acid in rat brain phospholipids are prolonged by 15 weeks of nutritional deprivation of n-3 polyunsaturated fatty acids

Male rat pups (21 days old) were placed on a diet deficient in n-3 polyunsaturated fatty acids (PUFAs) or on an n-3 PUFA adequate diet containing alpha-linolenic acid (alpha-LNA; 18 : 3n-3). After 15 weeks on a diet, [4,5-3H]docosahexaenoic acid (DHA; 22 : 6n-3) was injected into the right lateral cerebral ventricle, and the rats were killed at fixed times over a period of 60 days. Compared with the adequate diet, 15 weeks of n-3 PUFA deprivation reduced plasma DHA by 89% and brain DHA by 37%; these DHA concentrations did not change thereafter. In the n-3 PUFA adequate rats, DHA loss half-lives, calculated by plotting log10 (DHA radioactivity) against time after tracer injection, equaled 33 days in total brain phospholipid, 23 days in phosphatidylcholine, 32 days in phosphatidylethanolamine, 24 days in phosphatidylinositol and 58 days in phosphatidylserine; all had a decay slope significantly greater than 0 (p < 0.05). In the n-3 PUFA deprived rats, these half-lives were prolonged twofold or greater, and calculated rates of DHA loss from brain, Jout, were reduced. Mechanisms must exist in the adult rat brain to minimize DHA metabolic loss, and to do so even more effectively in the face of reduced n-3 PUFA availability for only 15 weeks.

Essential fatty acids in Huntington's disease

Huntington's disease is an inherited neurodegenerative disorder due to a mutation in exon 1 of the Huntingtin gene that encodes a stretch of polyglutamine (polyQ) residues close to the N-terminus of the huntingtin protein. Aggregated polyQ residues are highly toxic to the neuronal cells when they enter the cell nucleus. The mechanisms by which aggregated polyQ induces neurodegeneration include the binding of abnormal huntingtin to cyclic adenosine monophosphate response element binding protein, which hampers its ability to turn on transcription of other genes; mutant huntingtin binding to the active site on the cyclic adenosine monophosphate response element binding protein, which is essential for its acetyltransferase activity and, hence, the drugs that inhibit histone deacetylase arrest polyQ-dependent neurodegeneration; and/or disrupting the ubiquitin-proteasome system. Transgenic R6/1 mice that incorporate a human genomic fragment containing promoter elements exon 1 and a portion of intron 2 of the huntingtin gene responsible for Huntington's disease develop late-onset neurologic deficits in a manner similar to the motor abnormalities of Huntington's disease and show increased survival rates and decreased neurologic deficits when supplemented with essential fatty acids throughout life. A randomized, placebo-controlled, double-blind study has shown that highly unsaturated fatty acids are beneficial to patients with Huntington's disease. These results raise the possibility that unsaturated fatty acids may prevent or arrest polyQ aggregation, inhibit histone deacetylase, and/or activate the ubiquitin-proteasome system. In view of the encouraging results with essential fatty acids in Huntington's disease, it is proposed that their possible use in other neurodegenerative conditions need to be explored.

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.

Docosahexaenoic acid: membrane properties of a unique fatty acid

Docosahexaenoic acid (DHA) with 22-carbons and 6 double bonds is the extreme example of an omega-3 polyunsaturated fatty acid (PUFA). DHA has strong medical implications since its dietary presence has been positively linked to the prevention of numerous human afflictions including cancer and heart disease. The PUFA, moreover, is essential to neurological function. It is remarkable that one simple molecule has been reported to affect so many seemingly unrelated biological processes. Although details of a molecular mode of action remain elusive, DHA must be acting at a fundamental level common to many tissues that is related to the high degree of conformational flexibility that the multiple double bonds have been identified to confer. One likely target for DHA action is at the cell membrane where the fatty acid is known to readily incorporate into membrane phospholipids. Once esterified into phospholipids DHA has been demonstrated to significantly alter many basic properties of membranes including acyl chain order and "fluidity", phase behavior, elastic compressibility, permeability, fusion, flip-flop and protein activity. It is concluded that DHA's interaction with other membrane lipids, particularly cholesterol, may play a prominent role in modulating the local structure and function of cell membranes.

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.

Neuroprotective effect of developmental docosahexaenoic acid supplement against excitotoxic brain damage in infant rats

Long-chain polyunsaturated fatty acid (LC-PUFA) composition of neural membranes is a key factor for brain development, in chemical communication of neurons and probably also their survival in response to injury. Viability of cholinergic neurons was tested during brain development following dietary supplementation of fish oil LC-PUFAs (docosahexaenoic acid [DHA], eicosapentaenoic acid, arachidonic acid) in the food of mother rats. Excitotoxic injury was introduced by N-methyl-D,L-aspartate (NMDA) injection into the cholinergic nucleus basalis magnocellularis of 14-day-old rats. The degree of loss of cholinergic cell bodies, and the extend of axonal and dendritic disintegration were measured following immunocytochemical staining of cell bodies and dendrites for choline acetyltransferase and p75 low-affinity neurotrophin receptor and by histochemical staining of acetylcholinesterase-positive fibres in the parietal neocortex. The impact of different feeding regimens on fatty acid composition of neural membrane phospholipids was also assayed at 12 days of age. Supplementation of LC-PUFAs resulted in a resistance against NMDA-induced excitotoxic degeneration of cholinergic neurones in the infant rats. More cholinergic cells survived, the dendritic involution of surviving neurons in the penumbra region decreased, and the degeneration of axons at the superficial layers of parietal neocortex also attenuated after supplementing LC-PUFAs. A marked increment in DHA content in all types of phospholipids was obtained in the forebrain neuronal membrane fraction of supplemented rats. It is concluded that fish oil LC-PUFAs, first of all DHA, is responsible for the neuroprotective action on developing cholinergic neurons against glutamate cytotoxicity.

Effects of unsaturated fatty acids and triacylglycerols on phosphatidylethanolamine membrane structure

Lipid intake in diet regulates the membrane lipid composition, which in turn controls activities of membrane proteins. There is evidence that fatty acids (FAs) and triacylglycerols (TGs) can alter the phospholipid (PL) mesomorphism. However, the molecular mechanisms involved are not fully understood. This study focuses on the effect of the unsaturation degree of the C-18 FAs, oleic acid (OA), linoleic acid and linolenic acid, and their TGs, triolein (TO), trilinolein, and trilinolenin, on the structural properties of phosphoethanolamine PLs. By means of X-ray diffraction and 31P-NMR spectroscopy, it is shown that both types of molecules stabilize the HII phase in 1,2-dielaidoyl-sn-glycero-3-phosphoethanolamine (DEPE) liposomes. Several structural factors are considered to explain the correlation between the FA unsaturation degree and the onset temperature of the HII phase. It is proposed that TGs could act as lateral spacers between polar DEPE groups, providing an increase in the effective surface area per lipid molecule that would account for the structural parameters of the HII phase. Fluorescence polarization data indicated a fluidification effect of OA on the lamellar phase. TO increased the viscosity of the hydrophobic core with a high effect on the HII phase.

Effect of reduced maternal protein intake in pregnancy in the rat on the fatty acid composition of brain, liver, plasma, heart and lung phospholipids of the offspring after weaning

Reduced protein intake during pregnancy decreased maternal hepatic and plasma docosahexaenoic acid concentrations and impaired docosahexaenoic acid accumulation into fetal brain in the rat. The present study investigated whether restriction of maternal protein intake during pregnancy in the rat alters membrane phospholipid fatty acid composition in the offspring after weaning. Female rats (six per group) were mated and fed diets containing either 180 or 90 g protein/kg throughout pregnancy. Mothers were transferred to standard chow after delivery and the litters reduced to eight pups. Weaning was at 28 d and pups were killed 5 to 6 d later. Tissue weights or membrane total phosphatidylcholine (PC) and phosphatidylethanolamine (PE) concentrations in the offspring did not differ between dietary groups. There were significant differences between the 180 and 90 g/kg groups in liver, brain, lung and heart fatty acid composition that differed between tissues and phospholipid classes. For example, docosahexaenoic and arachidonic acid concentrations were 23 and 10 % lower respectively in hepatic PC, but not PE, in the 90 g/kg group. In brain, docosahexaenoic acid concentration was 17 % lower in PC, but not PE, while arachidonic acid content was 21 % greater in PE but unchanged in PC. The greatest differences were in unsaturated fatty acids, which suggests alterations to desaturase activities and/or the specificity of phospholipid biosynthesis. These results suggest that restricted maternal protein intake during pregnancy results in persistent alterations to membrane fatty acid content.