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

Mitochondrial dysfunctions in myalgic encephalomyelitis/chronic fatigue syndrome explained by activated immuno-inflammatory, oxidative and nitrosative stress pathways

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/cfs) is classified by the World Health Organization as a disorder of the central nervous system. ME/cfs is an neuro-immune disorder accompanied by chronic low-grade inflammation, increased levels of oxidative and nitrosative stress (O&NS), O&NS-mediated damage to fatty acids, DNA and proteins, autoimmune reactions directed against neoantigens and brain disorders. Mitochondrial dysfunctions have been found in ME/cfs, e.g. lowered ATP production, impaired oxidative phosphorylation and mitochondrial damage. This paper reviews the pathways that may explain mitochondrial dysfunctions in ME/cfs. Increased levels of pro-inflammatory cytokines, such as interleukin-1 and tumor necrosis factor-α, and elastase, and increased O&NS may inhibit mitochondrial respiration, decrease the activities of the electron transport chain and mitochondrial membrane potential, increase mitochondrial membrane permeability, interfere with ATP production and cause mitochondrial shutdown. The activated O&NS pathways may additionally lead to damage of mitochondrial DNA and membranes thus decreasing membrane fluidity. Lowered levels of antioxidants, zinc and coenzyme Q10, and ω3 polyunsaturated fatty acids in ME/cfs may further aggravate the activated immuno-inflammatory and O&NS pathways. Therefore, it may be concluded that immuno-inflammatory and O&NS pathways may play a role in the mitochondrial dysfunctions and consequently the bioenergetic abnormalities seen in patients with ME/cfs. Defects in ATP production and the electron transport complex, in turn, are associated with an elevated production of superoxide and hydrogen peroxide in mitochondria creating adaptive and synergistic damage. It is argued that mitochondrial dysfunctions, e.g. lowered ATP production, may play a role in the onset of ME/cfs symptoms, e.g. fatigue and post exertional malaise, and may explain in part the central metabolic abnormalities observed in ME/cfs, e.g. glucose hypometabolism and cerebral hypoperfusion.

Omega-3 fatty acids alter behavioral and oxidative stress parameters in animals subjected to fenproporex administration

Studies have consistently reported the participation of oxidative stress in bipolar disorder (BD). Evidences indicate that omega-3 (ω3) fatty acids play several important roles in brain development and functioning. Moreover, preclinical and clinical evidence suggests roles for ω3 fatty acids in BD. Considering these evidences, the present study aimed to investigate the effects of ω3 fatty acids on locomotor behavior and oxidative stress parameters (TBARS and protein carbonyl content) in brain of rats subjected to an animal model of mania induced by fenproporex. The fenproporex treatment increased locomotor behavior in saline-treated rats under reversion and prevention model, and ω3 fatty acids prevented fenproporex-related hyperactivity. Moreover, fenproporex increased protein carbonyls in the prefrontal cortex and cerebral cortex, and the administration of ω3 fatty acids reversed this effect. Lipid peroxidation products also are increased in prefrontal cortex, striatum, hippocampus and cerebral after fenproporex administration, but ω3 fatty acids reversed this damage only in the hippocampus. On the other hand, in the prevention model, fenproporex increased carbonyl content only in the cerebral cortex, and administration of ω3 fatty acids prevented this damage. Additionally, the administration of fenproporex resulted in a marked increased of TBARS in the prefrontal cortex, hippocampus, striatum and cerebral cortex, and prevent this damage in the prefrontal cortex, hippocampus and striatum. In conclusion, we are able to demonstrate that fenproporex-induced hyperlocomotion and damage through oxidative stress were prevented by ω3 fatty acids. Thus, the ω3 fatty acids may be important adjuvant therapy of bipolar disorder.

The omega-6/omega-3 ratio and dementia or cognitive decline: a systematic review on human studies and biological evidence

It has been suggested that the intake of certain fatty acids may influence the risk of dementia. However, current reviews have focused only on the therapeutic effects of omega-3 fatty acids, mostly as supplements. To date, the evidence for the relevance of the omega-6/omega-3 ratio has been neglected. Therefore, we searched the databases Alois, Medline, Biosis, Embase, Cochrane Central Register of Controlled Trials, and The Cochrane Database of Systematic Reviews for "essential fatty acids" and "dementia" and aimed to conduct a comprehensive review across study types. All studies that reported on the association between the n-6/n-3 ratio and dementia or cognitive decline were selected. In the 13 animal studies we examined, the dietary n-6/n-3 ratio was shown to affect brain composition, Alzheimer's disease pathology, and behavior. Our review of the 14 studies in humans that fulfilled the selection criteria (7 prospective studies, 3 cross-sectional studies, 1 controlled trial, 3 case-control studies) provided evidence, albeit limited, supporting an association between the n-6/n-3 ratio, cognitive decline, and incidence of dementia. This review supports growing evidence of a positive association between the dietary n-6/n-3 ratio and the risk of Alzheimer's disease.

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

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

Whole body synthesis rates of DHA from α-linolenic acid are greater than brain DHA accretion and uptake rates in adult rats

Docosahexaenoic acid (DHA) is important for brain function, however, the exact amount required for the brain is not agreed upon. While it is believed that the synthesis rate of DHA from α-linolenic acid (ALA) is low, how this synthesis rate compares with the amount of DHA required to maintain brain DHA levels is unknown. The objective of this work was to assess whether DHA synthesis from ALA is sufficient for the brain. To test this, rats consumed a diet low in n-3 PUFAs, or a diet containing ALA or DHA for 15 weeks. Over the 15 weeks, whole body and brain DHA accretion was measured, while at the end of the study, whole body DHA synthesis rates, brain gene expression, and DHA uptake rates were measured. Despite large differences in body DHA accretion, there was no difference in brain DHA accretion between rats fed ALA and DHA. In rats fed ALA, DHA synthesis and accretion was 100-fold higher than brain DHA accretion of rats fed DHA. Also, ALA-fed rats synthesized approximately 3-fold more DHA than the DHA uptake rate into the brain. This work indicates that DHA synthesis from ALA may be sufficient to supply the brain.

Differential expression and regulatory roles of FABP5 and FABP7 in oligodendrocyte lineage cells

Fatty-acid-binding proteins (FABPs) are key intracellular molecules involved in the uptake, transportation and storage of fatty acids and in the mediation of signal transduction and gene transcription. However, little is known regarding their expression and function in the oligodendrocyte lineage. We evaluate the in vivo and in vitro expression of FABP5 and FABP7 in oligodendrocyte lineage cells in the cortex and corpus callosum of adult mice, mixed cortical culture and oligosphere culture by immunofluorescent counter-staining with major oligodendrocyte lineage markers. In all settings, FABP7 expression was detected in NG2(+)/PDGFRα(+) oligodendrocyte progenitor cells (OPCs) that did not express FABP5. FABP5 was detected in mature CC1(+)/MBP(+) oligodendrocytes that did not express FABP7. Analysis of cultured OPCs showed a significant decrease in the population of FABP7-knockout (KO) OPCs and their BrdU uptake compared with wild-type (WT) OPCs. Upon incubation of OPCs in oligodendrocyte differentiation medium, a significantly lower percentage of FABP7-KO OPCs differentiated into O4(+) oligodendrocytes. The percentage of mature MBP(+) oligodendrocytes relative to whole O4(+)/MBP(+) oligodendrocytes was significantly lower in FABP7-KO and FABP5-KO than in WT cell populations. The percentage of terminally mature oligodendrocytes with membrane sheet morphology was significantly lower in FABP5-KO compared with WT cell populations. Thus, FABP7 and FABP5 are differentially expressed in oligodendrocyte lineage cells and regulate their proliferation and/or differentiation. Our findings suggest the involvement of FABP7 and FABP5 in the pathophysiology of demyelinating disorders, neuropsychiatric disorder and glioma, conditions in which OPCs/oligodendrocytes play central roles.

Omega-3 polyunsaturated fatty acid (PUFA) status in major depressive disorder with comorbid anxiety disorders

BACKGROUND

Although lower levels of omega-3 polyunsaturated fatty acids (PUFAs) are found in major depressive disorder, less is known about PUFA status and anxiety disorders.

METHOD

Medication-free participants with DSM-IV-defined major depressive disorder (MDD), with (n = 18) and without (n = 41) comorbid DSM-IV anxiety disorders, and healthy volunteers (n = 62) were recruited from October 2006 to May 2010 for mood disorder studies at the New York State Psychiatric Institute. Participants were 18-73 years of age (mean age, 35.8 ± 12.6 years). Depression and anxiety severity was assessed using depression and anxiety subscales from the 17-item Hamilton Depression Rating Scale. Plasma PUFAs eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) and the ratio of arachidonic acid (AA; 22:4n-6) to EPA (AA:EPA) were quantified. This secondary analysis employed analysis of variance with a priori planned contrasts to test for diagnostic group differences in log-transformed PUFA levels (logDHA, logEPA, and logAA:EPA).

RESULTS

Plasma levels of logDHA (F(2,118) = 4.923, P = .009), logEPA (F(2,118) = 6.442, P = .002), and logAA:EPA (F(2,118) = 3.806, P = .025) differed across groups. Participants with MDD had lower logDHA (t(118) = 2.324, P = .022) and logEPA (t(118) = 3.175, P = .002) levels and higher logAA:EPA levels (t(118) = -2.099, P = .038) compared with healthy volunteers. Lower logDHA (t(118) = 2.692, P = .008) and logEPA (t(118) = 2.524, P = .013) levels and higher logAA:EPA levels (t(118) = -2.322, P = .022) distinguished anxious from nonanxious MDD. Depression severity was not associated with PUFA plasma levels; however, anxiety severity across the entire sample correlated negatively with logDHA (r(p) = -0.22, P = .015) and logEPA (r(p) = -0.25, P = .005) levels and positively with logAA:EPA levels (r(p) = 0.18, P = .043).

CONCLUSIONS

The presence and severity of comorbid anxiety were associated with the lowest EPA and DHA levels. Further studies are needed to elucidate whether omega-3 PUFA supplementation may preferentially alleviate MDD with more severe anxiety.

Perturbations in blood phosphatidylcholine and sphingomyelin Fatty Acid composition in a sample population of cigarette smokers

Docosahexaenoic (DHA) and arachidonic acids (AA) are polyunsaturated fatty acids (PUFAs), major components of brain tissue and neural systems, and the precursors of a number of biologically active metabolites with functions in inflammation resolution, neuroprotection and other actions. As PUFAs are highly susceptible to peroxidation, we hypothesised whether cigarette smokers would present altered PUFAs levels in plasma and erythrocyte phospholipids. Adult males from Indian, Sri-Lankan or Bangladeshi genetic backgrounds who reported smoking between 20 and 60 cigarettes per week were recruited. The control group consisted of matched non-smokers. A blood sample was taken, plasma and erythrocyte total lipids were extracted, phospholipids were separated by thin layer chromatography, and the fatty acid content analysed by gas chromatography. In smokers, dihomo-gamma-linolenic acid, the AA precursor, was significantly reduced in plasma and erythrocyte phosphatidylcholine. AA and DHA were significantly reduced in erythrocyte sphingomyelin. Relatively short term smoking has affected the fatty acid composition of plasma and erythrocyte phospholipids with functions in neural tissue composition, cell signalling, cell growth, intracellular trafficking, neuroprotection and inflammation, in a relatively young population. As lipid peroxidation is pivotal in the pathogenesis of atherosclerosis and neurodegenerative diseases such as Alzheimer disease, early effects of smoking may be relevant for the development of such conditions.

The effect of maternal omega-3 (n-3) LCPUFA supplementation during pregnancy on early childhood cognitive and visual development: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Maternal fish consumption during pregnancy has been positively associated with cognitive and visual abilities in the offspring, leading to the hypothesis that maternal omega-3 (n-3) long-chain PUFA (LCPUFA) supplementation improves children's neurologic and visual development.

OBJECTIVE

The objective was to evaluate the effect of maternal omega-3 LCPUFA supplementation in pregnancy on neurologic and visual development in the offspring.

DESIGN

Five electronic databases were searched. Human randomized controlled trials that supplemented the maternal diet with omega-3 LCPUFAs during pregnancy, or pregnancy and lactation, and that assessed either neurologic or visual development of the offspring were included. Trial quality was assessed, and the results of eligible trials were compared in meta-analyses.

RESULTS

Eleven RCTs involving 5272 participants were included in the review. Most trials had methodologic limitations. No differences in standardized psychometric test scores for cognitive, language, or motor development were observed between the LCPUFA-supplemented and control groups, except for cognitive scores in 2-5-y-old children, in whom supplementation resulted in higher Developmental Standard Scores (mean difference: 3.92; 95% CI: 0.77, 7.08; n = 156; P = 0.01). However, this effect was from 2 trials with a high risk of bias. Because of the variety of visual assessments and age ranges, it was not possible to combine studies with visual outcomes in a meta-analysis, although 6 of the 8 assessments in 5 trials reported no difference between the supplemented and control groups.

CONCLUSION

The evidence does not conclusively support or refute that omega-3 LCPUFA supplementation in pregnancy improves cognitive or visual development.

ω-3 fatty acid eicosapentaenoic acid attenuates MPP+-induced neurodegeneration in fully differentiated human SH-SY5Y and primary mesencephalic cells

Eicosapentaenoic acid (EPA), a neuroactive omega-3 fatty acid, has been demonstrated to exert neuroprotective effects in experimental models of Parkinson's disease (PD), but the cellular mechanisms of protection are unknown. Here, we studied the effects of EPA in fully differentiated human SH-SY5Y cells and primary mesencephalic neurons treated with MPP(+) . In both in-vitro models of PD, EPA attenuated an MPP(+) -induced reduction in cell viability. EPA also prevented the presence of electron-dense cytoplasmic inclusions in SH-SY5Y cells. Then, possible mechanisms of the neuroprotection were studied. In primary neurons, EPA attenuated an MPP(+) -induced increase in Tyrosine-related kinase B (TrkB) receptors. In SH-SY5Y cells, EPA down-regulated reactive oxygen species and nitric oxide. This antioxidant effect of EPA may have been mediated by its inhibition of neuronal NADPH oxidase and cyclo-oxygenase-2 (COX-2), as MPP(+) increased the expression of these enzymes. Furthermore, EPA prevented an increase in cytosolic phospholipase A2 (cPLA2), an enzyme linked with COX-2 in the potentially pro-inflammatory arachidonic acid cascade. Lastly, EPA attenuated an increase in the bax:bcl-2 ratio, and cytochrome c release. However, EPA did not prevent mitochondrial enlargement or a decrease in mitochondrial membrane potential. This study demonstrated cellular mechanisms by which EPA provided neuroprotective effects in experimental PD.

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

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

A quantum theory for the irreplaceable role of docosahexaenoic acid in neural cell signalling throughout evolution

Six hundred million years ago, the fossil record displays the sudden appearance of intracellular detail and the 32 phyla. The "Cambrian Explosion" marks the onset of dominant aerobic life. Fossil intracellular structures are so similar to extant organisms that they were likely made with similar membrane lipids and proteins, which together provided for organisation and specialisation. While amino acids could be synthesised over 4 billion years ago, only oxidative metabolism allows for the synthesis of highly unsaturated fatty acids, thus producing novel lipid molecular species for specialised cell membranes. Docosahexaenoic acid (DHA) provided the core for the development of the photoreceptor, and conversion of photons into electricity stimulated the evolution of the nervous system and brain. Since then, DHA has been conserved as the principle acyl component of photoreceptor synaptic and neuronal signalling membranes in the cephalopods, fish, amphibian, reptiles, birds, mammals and humans. This extreme conservation in electrical signalling membranes despite great genomic change suggests it was DHA dictating to DNA rather than the generally accepted other way around. We offer a theoretical explanation based on the quantum mechanical properties of DHA for such extreme conservation. The unique molecular structure of DHA allows for quantum transfer and communication of π-electrons, which explains the precise depolarisation of retinal membranes and the cohesive, organised neural signalling which characterises higher intelligence.

Responses to n-3 fatty acid (LCPUFA) supplementation of gestating gilts, and lactating and weaned sows

Feeding n-3 long-chain polyunsaturated fatty acids (LCPUFA) to gilts or sows has shown different responses to litter growth, pre-weaning mortality and subsequent reproductive performance of the sow. Two hypotheses were tested: (1) that feeding a marine oil-based supplement rich in protected n-3 LCPUFAs to gilts in established gestation would improve the growth performance of their litters; and (2) that continued feeding of the supplement during lactation and after weaning would offset the negative effects of lactational catabolism induced, using an established experimental model involving feed restriction of lactating primiparous sows. A total of 117 primiparous sows were pair-matched at day 60 of gestation by weight, and when possible, litter of origin, and were allocated to be either control sows (CON) fed standard gestation and lactation diets, or treated sows (LCPUFA) fed the standard diets supplemented with 84 g/day of a n-3 LCPUFA rich supplement, from day 60 of first gestation, through a 21-day lactation, and until euthanasia at day 30 of their second gestation. All sows were feed restricted during the last 7 days of lactation to induce catabolism, providing a background challenge against which to determine beneficial effects of n-3 LCPUFA supplementation on subsequent reproduction. In the absence of an effect on litter size or birth weight, n-3 LCPUFA tended to improve piglet BW gain from birth until 34 days after weaning (P = 0.06), while increasing pre-weaning mortality (P = 0.05). It did not affect energy utilization by the sow during lactation, thus not improving the catabolic state of the sows. Supplementation from weaning until day 30 of second gestation did not have an effect on embryonic weight, ovulation rate or early embryonic survival, but did increase corpora lutea (CL) weight (P = 0.001). Eicosapentaenoic acid and docosahexaenoic acid (DHA) levels were increased in sow serum and CL (P < 0.001), whereas only DHA levels increased in embryos (P < 0.01). In conclusion, feeding n-3 LCPUFA to gilts tended to improve litter growth, but did not have an effect on overall subsequent reproductive performance.

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

BACKGROUND

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

RESULTS

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

CONCLUSION

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

Fetal and neonatal levels of omega-3: effects on neurodevelopment, nutrition, and growth

Nutrition in pregnancy, during lactation, childhood, and later stages has a fundamental influence on overall development. There is a growing research interest on the role of key dietary nutrients in fetal health. Omega-3 polyunsaturated fatty acids (n-3 LCPUFAs) play an important role in brain development and function. Evidence from animal models of dietary n-3 LCPUFAs deficiency suggests that these fatty acids promote early brain development and regulate behavioral and neurochemical aspects related to mood disorders (stress responses, depression, and aggression and growth, memory, and cognitive functions). Preclinical and clinical studies suggest the role of n-3 LCPUFAs on neurodevelopment and growth. n-3 LCPUFAs may be an effective adjunctive factor for neural development, growth, and cognitive development, but further large-scale, well-controlled trials and preclinical studies are needed to examine its clinical mechanisms and possible benefits. The present paper discusses the use of n-3 LCPUFAs during different developmental stages and the investigation of different sources of consumption. The paper summarizes the role of n-3 LCPUFAs levels during critical periods and their effects on the children's neurodevelopment, nutrition, and growth.

Differential vulnerability of substantia nigra and corpus striatum to oxidative insult induced by reduced dietary levels of essential fatty acids

Oxidative stress (OS) has been implicated in the etiology of certain neurodegenerative disorders. Some of these disorders have been associated with unbalanced levels of essential fatty acids (EFA). The response of certain brain regions to OS, however, is not uniform and a selective vulnerability or resilience can occur. In our previous study on rat brains, we observed that a two-generation EFA dietary restriction reduced the number and size of dopaminergic neurons in the substantia nigra (SN) rostro-dorso-medial. To understand whether OS contributes to this effect, we assessed the status of lipid peroxidation (LP) and anti-oxidant markers in both SN and corpus striatum (CS) of rats submitted to this dietary treatment for one (F1) or two (F2) generations. Wistar rats were raised from conception on control or experimental diets containing adequate or reduced levels of linoleic and α-linolenic fatty acids, respectively. LP was measured using the thiobarbituric acid reaction method (TBARS) and the total superoxide dismutase (t-SOD) and catalase (CAT) enzymatic activities were assessed. The experimental diet significantly reduced the docosahexaenoic acid (DHA) levels of SN phospholipids in the F1 (~28%) and F2 (~50%) groups. In F1 adult animals of the experimental group there was no LP in both SN and CS. Consistently, there was a significant increase in the t-SOD activity (p < 0.01) in both regions. In EF2 young animals, degeneration in dopaminergic and non-dopaminergic neurons and a significant increase in LP (p < 0.01) and decrease in the CAT activity (p < 0.001) were detected in the SN, while no inter-group difference was found for these parameters in the CS. Conversely, a significant increase in t-SOD activity (p < 0.05) was detected in the CS of the experimental group compared to the control. The results show that unbalanced EFA dietary levels reduce the redox balance in the SN and reveal mechanisms of resilience in the CS under this stressful condition.

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

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

Clinical and biochemical validation of two endophenotypes of schizophrenia defined by levels of polyunsaturated fatty acids in red blood cells

BACKGROUND

Polyunsaturated fatty acids (PUFAs) are bimodally distributed in acute schizophrenia, suggesting two endophenotypes. We intended to characterize these endophenotypes clinically. Our a priori hypothesis was that low PUFA patients have more negative symptoms.

PATIENTS AND METHODS

Patients (aged 18-39) with schizophrenia, schizoaffective or schizophreniform disorders were recruited at hospital admission during an acute episode. The baseline Positive and Negative Syndrome Scale, vital signs and biochemical variables were measured in 97 patients with available RBC PUFA levels. Adjustment for multiple testing was not performed.

RESULTS

The median Negative Subscale score was higher (p=0.04) in the low PUFA (25 points, n=30) than in the high PUFA group (19 points, n=67). Among 95 patients with measurements of serum triglycerides, hypertriglyceridaemia was more prevalent (p=0.009) among low PUFA patients (66%) than high PUFA patients (36%). PUFA modified the effect of antipsychotics on triglycerides (p=0.046). Serum glucose and mean corpuscular haemoglobin were higher (p=0.03, 0.001, respectively) in low PUFA than in high PUFA patients. Low PUFA men were heavier (p=0.04) than high PUFA men.

CONCLUSIONS

During an acute episode of schizophrenia, patients with low RBC PUFA have more negative symptoms and more metabolic and haematological abnormalities than those with high PUFA. This indicates that PUFA levels define two clinically distinct endophenotypes of the disorder.

Nutritional n-3 polyunsaturated fatty acids deficiency alters cannabinoid receptor signaling pathway in the brain and associated anxiety-like behavior in mice

N-3 polyunsaturated fatty acids (PUFAs) cannot be synthesized de novo in mammals and need to be provided by dietary means. In the brain, the main n-3 PUFA is docosahexaenoic acid (DHA), which is a key component of neuronal membranes. A low dietary level of DHA has been associated with increased risk of developing neuropsychiatric diseases; however, the mechanisms involved remain to be determined. In this study, we found that long-term exposure to an n-3 deficient diet decreases the level of DHA in the brain and impairs the cannabinoid receptor signaling pathway in mood-controlling structures. In n-3 deficient mice, the effect of the cannabinoid agonist WIN55,212-2 in an anxiety-like behavior test was abolished. In addition, the cannabinoid receptor signaling pathways were altered in the prefrontal cortex and the hypothalamus. Consequently, our data suggest that behavioral changes linked to an n-3 dietary deficiency are due to an alteration in the endocannabinoid system in specific brain areas.

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

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

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

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

Transthyretin and the brain re-visited: is neuronal synthesis of transthyretin protective in Alzheimer's disease?

Since the mid-1990's a trickle of publications from scattered independent laboratories have presented data suggesting that the systemic amyloid precursor transthyretin (TTR) could interact with the amyloidogenic β-amyloid (Aβ) peptide of Alzheimer's disease (AD). The notion that one amyloid precursor could actually inhibit amyloid fibril formation by another seemed quite far-fetched. Further it seemed clear that within the CNS, TTR was only produced in choroid plexus epithelial cells, not in neurons. The most enthusiastic of the authors proclaimed that TTR sequestered Aβ in vivo resulting in a lowered TTR level in the cerebrospinal fluid (CSF) of AD patients and that the relationship was salutary. More circumspect investigators merely showed in vitro interaction between the two molecules. A single in vivo study in Caenorhabditis elegans suggested that wild type human TTR could suppress the abnormalities seen when Aβ was expressed in the muscle cells of the worm. Subsequent studies in human Aβ transgenic mice, including those from our laboratory, also suggested that the interaction reduced the Aβ deposition phenotype. We have reviewed the literature analyzing the relationship including recent data examining potential mechanisms that could explain the effect. We have proposed a model which is consistent with most of the published data and current notions of AD pathogenesis and can serve as a hypothesis which can be tested.

Hypothalamic gene expression in ω-3 PUFA-deficient male rats before, and following, development of hypertension

Dietary deficiency of ω-3 fatty acids (ω-3 DEF) produces hypertension in later life. This study examined the effect of ω-3 DEF on blood pressure and hypothalamic gene expression in young rats, before the development of hypertension, and in older rats following the onset of hypertension. Animals were fed experimental diets that were deficient in ω-3 fatty acids, sufficient in short-chain ω-3 fatty acids or sufficient in short- and long-chain ω-3 fatty acids, from the prenatal period until 10 or 36 weeks-of-age. There was no difference in blood pressure between groups at 10 weeks-of-age; however, at 36 weeks-of-age ω-3 DEF animals were hypertensive in relation to sufficient groups. At 10 weeks, expression of angiotensin-II(1A) receptors and dopamine D(3) receptors were significantly increased in the hypothalamic tissue of ω-3 DEF animals. In contrast, at 36 weeks, α(2a) and β(1) adrenergic receptor expression was significantly reduced in the ω-3 DEF group. Brain docosahexaenoic acid was significantly lower in ω-3 DEF group compared with sufficient groups. This study demonstrates that dietary ω-3 DEF causes changes both in the expression of key genes involved in central blood pressure regulation and in blood pressure. The data may indicate that hypertension resulting from ω-3 DEF is mediated by the central adrenergic system.

Identification of novel mammalian phospholipids containing threonine, aspartate, and glutamate as the base moiety

In this study, we showed the occurrence of phosphatidyl-L-threonine (PThr), phosphatidyl-L-aspartate (PAsp), and phosphatidyl-L-glutamate (PGlu) in rat brain. Analyses using an HPLC-ESI-MS and an amino acid analyzer showed the presence of L-threonine, L-aspartate, and L-glutamate in the acid-hydrolysates of phospholipids from porcine cerebrum, rat cerebrum, and rat liver. Results of ESI-MS/MS analyses with neutral loss scanning and product ion scanning suggest the presence of PThr-(18:0, 18:1), PThr-(18:0, 22:6), PAsp-(18:0, 18:1), PAsp-(18:0, 22:6), PGlu-(18:0, 18:1), and PGlu-(18:0, 22:6) in rat brain. This is the first study to identify 2 novel phospholipids, PAsp and PGlu, with a carboxylate-phosphate anhydride bond, in living organisms.

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

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

Therapeutic use of omega-3 fatty acids in bipolar disorder

Bipolar disorder (BD) is a severe, chronic affective disorder, associated with significant disability, morbidity and premature mortality. Omega-3 polyunsaturated fatty acids (PUFAs) play several important roles in brain development and functioning. Evidence from animal models of dietary omega-3 (n-3) PUFA deficiency suggest that these fatty acids are relevant to promote brain development and to regulate behavioral and neurochemical aspects related to mood disorders, such as stress responses, depression and aggression, as well as dopaminergic content and function. Preclinical and clinical evidence suggests roles for PUFAs in BD. n-3 PUFAs seem to be an effective adjunctive treatment for unipolar and bipolar depression, but further large-scale, well-controlled trials are needed to examine its clinical utility in BD. The use of n-3 as a mood stabilizer among BD patients is discussed here. This article summarizes the molecular pathways related to the role of n-3 as a neuroprotective and neurogenic agent, with a specific focus on BDNF. It is proposed that the n-3-BDNF association is involved in the pathophysiology of BD and represents a promising target for developing a novel class of rationally devised therapies.

FABP7 expression in normal and stab-injured brain cortex and its role in astrocyte proliferation

Reactive gliosis, in which astrocytes as well as other types of glial cells undergo massive proliferation, is a common hallmark of all brain pathologies. Brain-type fatty acid-binding protein (FABP7) is abundantly expressed in neural stem cells and astrocytes of developing brain, suggesting its role in differentiation and/or proliferation of glial cells through regulation of lipid metabolism and/or signaling. However, the role of FABP7 in proliferation of glial cells during reactive gliosis is unknown. In this study, we examined the expression of FABP7 in mouse cortical stab injury model and also the phenotype of FABP7-KO mice in glial cell proliferation. Western blotting showed that FABP7 expression was increased significantly in the injured cortex compared with the contralateral side. By immunohistochemistry, FABP7 was localized to GFAP⁺ astrocytes (21% of FABP7⁺ cells) and NG2⁺ oligodendrocyte progenitor cells (62%) in the normal cortex. In the injured cortex there was no change in the population of FABP7⁺/NG2⁺ cells, while there was a significant increase in FABP7⁺/GFAP⁺ cells. In the stab-injured cortex of FABP7-KO mice there was decrease in the total number of reactive astrocytes and in the number of BrdU⁺ astrocytes compared with wild-type mice. Primary cultured astrocytes from FABP7-KO mice also showed a significant decrease in proliferation and omega-3 fatty acid incorporation compared with wild-type astrocytes. Overall, these data suggest that FABP7 is involved in the proliferation of astrocytes by controlling cellular fatty acid homeostasis.

Impact of ω-3 fatty acids in Parkinson's disease

Current epidemiological, preclinical and clinical data suggest that omega-3 polyunsaturated fatty acids (n-3 PUFAs) may constitute therapeutic strategy for several disorders of the central nervous system, including Parkinson's disease (PD). PD is a neurodegenerative disorder primarily characterized by motor symptoms but which also includes several other pathological features such as autonomic system failures, mood disorders, and cognitive deficits. Current pharmacological options for the disease are limited to symptom management and their long-term use leads to important side effects. In this review, we discuss the evidence for the effects of n-3 PUFAs in PD both from an epidemiological perspective as well as in light of data gathered on various pathological features of the disease. Effects of n-3 PUFAs on the dopaminergic system, α-synucleinopathy, their possible mechanisms of action as well as their therapeutic potential for PD patients are also reviewed. n-3 PUFAs are inexpensive, readily transferable to the clinical setting and their use could represent a neuroprotective strategy or a disease-modifying option to delay the appearance of symptoms. It could also be beneficial as a symptomatologic treatment or serve as an add-on therapy to current pharmacological approaches. Review of the current literature as well as the undertaking of future clinical trials will shed light on these possibilities.

Association between plasma metabolites and gene expression profiles in five porcine endocrine tissues

Background

Endocrine tissues play a fundamental role in maintaining homeostasis of plasma metabolites such as non-esterified fatty acids and glucose, the levels of which reflect the energy balance or the health status of animals. However, the relationship between the transcriptome of endocrine tissues and plasma metabolites has been poorly studied.

Methods

We determined the blood levels of 12 plasma metabolites in 27 pigs belonging to five breeds, each breed consisting of both females and males. The transcriptome of five endocrine tissues i.e. hypothalamus, adenohypophysis, thyroid gland, gonads and backfat tissues from 16 out of the 27 pigs was also determined. Sex and breed effects on the 12 plasma metabolites were investigated and associations between genes expressed in the five endocrine tissues and the 12 plasma metabolites measured were analyzed. A probeset was defined as a quantitative trait transcript (QTT) when its association with a particular metabolic trait achieved a nominal P value < 0.01.

Results

A larger than expected number of QTT was found for non-esterified fatty acids and alanine aminotransferase in at least two tissues. The associations were highly tissue-specific. The QTT within the tissues were divided into co-expression network modules enriched for genes in Kyoto Encyclopedia of Genes and Genomes or gene ontology categories that are related to the physiological functions of the corresponding tissues. We also explored a multi-tissue co-expression network using QTT for non-esterified fatty acids from the five tissues and found that a module, enriched in hypothalamus QTT, was positioned at the centre of the entire multi-tissue network.

Conclusions

These results emphasize the relationships between endocrine tissues and plasma metabolites in terms of gene expression. Highly tissue-specific association patterns suggest that candidate genes or gene pathways should be investigated in the context of specific tissues.

Marine omega-3 fatty acids and mood disorders--linking the sea and the soul. 'Food for Thought' I

OBJECTIVE

While there has long been interest in any nutritional contribution to the onset and treatment of mood disorders, there has been increasing scientific evaluation of several candidate nutritional and dietary factors in recent years. In this inaugural study of our 'Food for Thought' series, we will overview the evidence for any role of omega-3 fatty acids (FA) in regulating mood.

METHOD

Relevant literature was identified through online database searches and cross-referencing.

RESULTS

Plausible mechanisms exist by which omega-3 FA may influence neuronal function and mood. Cross-sectional studies demonstrate an association between omega-3 fatty acid deficiency and both depressive and bipolar disorders. Studies investigating the efficacy of omega-3 fatty acid supplementation for mood disorders have however provided inconsistent results. The proportion of treatment studies showing a significant advantage of omega-3 supplementation has dropped over the last 5 years. However, the vast heterogeneity of the trials in terms of constituent omega-3 FAs, dose and length of treatment makes comparisons of these studies difficult.

CONCLUSION

More research is required before omega-3 supplementation can be firmly recommended as an effective treatment for mood disorders. Whereas increased omega-3 FA intake may alleviate depressive symptoms, there is little evidence of any benefit for mania.

Retinoid x receptor gamma is implicated in docosahexaenoic acid modulation of despair behaviors and working memory in mice

BACKGROUND

Omega-3 polyunsaturated fatty acids, including docosahexaenoic acid (DHA), have antidepressant and promnemonic functions. The mechanisms of such activities are still elusive and may involve retinoid X receptors (RXRs), transcription factors known to bind DHA in vitro.

METHODS

Promnemonic and antidespair activities of acute DHA treatment were tested in BALBcByJ mice using spontaneous alternation and forced swim test, respectively. The involvement of retinoid receptors in such DHA activities was investigated using RXR and/or retinoic acid receptor (RAR) agonists to mimic DHA activities or a synthetic pan-RXR antagonist to block them. Involvement of RXR isotypes was analyzed using the same tasks and delayed nonmatch to place for working memory in RXRγ knockout mice.

RESULTS

Docosahexaenoic acid decreased despair behavior and improved working memory in BALBcByJ mice. Such effects were suppressed by co-treatment with BR1211, a pan-RXR antagonist, whereas a pan-RXR agonist, UVI2108, mimicked DHA activities. Retinoic acid (RA), a natural ligand of RXRs, also reduced despair behavior and improved working memory and such activities did not require activation of RARs, as RA effects were abolished by co-treatment with BR1211 and they were not reproduced by TTNPB, a pan-RAR agonist. The RXRγ knockout mice displayed increased despair and deficits in working memory, which were insensitive to DHA and pan-RXR agonist treatments, whereas DHA or UVI2108 reversed these deficits in RXRγ heterozygous mice.

CONCLUSIONS

Our data suggest that RXRs are a converging point in mediating DHA and RA modulations of despair behavior and working memory and that RXRγ is the predominant RXR isotype in these regulations.

Docosahexaenoic acid: brain accretion and roles in neuroprotection after brain hypoxia and ischemia

PURPOSE OF REVIEW

With important effects on neuronal lipid composition, neurochemical signaling and cerebrovascular pathobiology, docosahexaenoic acid (DHA), a n-3 polyunsaturated fatty acid, may emerge as a neuroprotective agent against cerebrovascular disease. This paper examines pathways for DHA accretion in brain and evidence for possible roles of DHA in prophylactic and therapeutic approaches for cerebrovascular disease.

RECENT FINDINGS

DHA is a major n-3 fatty acid in the mammalian central nervous system and enhances synaptic activities in neuronal cells. DHA can be obtained through diet or to a limited extent via conversion from its precursor, α-linolenic acid (α-LNA). DHA attenuates brain necrosis after hypoxic ischemic injury, principally by modulating membrane biophysical properties and maintaining integrity in functions between presynaptic and postsynaptic areas, resulting in better stabilizing intracellular ion balance in hypoxic-ischemic insult. Additionally, DHA alleviates brain apoptosis, by inducing antiapoptotic activities such as decreasing responses to reactive oxygen species, upregulating antiapoptotic protein expression, downregulating apoptotic protein expression, and maintaining mitochondrial integrity and function.

SUMMARY

DHA in brain relates to a number of efficient delivery and accretion pathways. In animal models DHA renders neuroprotection after hypoxic-ischemic injury by regulating multiple molecular pathways and gene expression.

Effects of maternal malnutrition and postnatal nutritional rehabilitation on brain fatty acids, learning, and memory

Undernutrition still affects mothers and children in developing countries and thus remains the major focus of nutritional intervention efforts. Neuronal development, which classically includes neurogenesis, migration, maturation, and synapse refinement, begins in utero and continues into the early postnatal period. These processes are not only genetically regulated but also clearly susceptible to environmental manipulation. Dietary deprivation during early life is known to have adverse effects on brain anatomy, physiology, and biochemistry, and may even lead to permanent brain damage. Although all nutrients are important for the structural development of the central nervous system, lipids such as long-chain polyunsaturated fatty acids, especially docosahexaenoic acid (22:6 n-3) and arachidonic acid (20:4 n-6), are important for normal brain development. The purpose of this literature review is to examine how early undernutrition involving a deficiency in long-chain polyunsaturated fatty acids can affect brain development and function and produce deficits in spatial cognitive learning ability.

The neurobiology of lipid metabolism in autism spectrum disorders

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

Brain fuel metabolism, aging, and Alzheimer's disease

Lower brain glucose metabolism is present before the onset of clinically measurable cognitive decline in two groups of people at risk of Alzheimer's disease--carriers of apolipoprotein E4, and in those with a maternal family history of AD. Supported by emerging evidence from in vitro and animal studies, these reports suggest that brain hypometabolism may precede and therefore contribute to the neuropathologic cascade leading to cognitive decline in AD. The reason brain hypometabolism develops is unclear but may include defects in brain glucose transport, disrupted glycolysis, and/or impaired mitochondrial function. Methodologic issues presently preclude knowing with certainty whether or not aging in the absence of cognitive impairment is necessarily associated with lower brain glucose metabolism. Nevertheless, aging appears to increase the risk of deteriorating systemic control of glucose utilization, which, in turn, may increase the risk of declining brain glucose uptake, at least in some brain regions. A contributing role of deteriorating glucose availability to or metabolism by the brain in AD does not exclude the opposite effect, i.e., that neurodegenerative processes in AD further decrease brain glucose metabolism because of reduced synaptic functionality and hence reduced energy needs, thereby completing a vicious cycle. Strategies to reduce the risk of AD by breaking this cycle should aim to (1) improve insulin sensitivity by improving systemic glucose utilization, or (2) bypass deteriorating brain glucose metabolism using approaches that safely induce mild, sustainable ketonemia.

Differential expression of FABP 3, 5, 7 in infantile and adult monkey cerebellum

To clarify the involvement of fatty acid binding proteins (FABPs) in cerebellar development and function, we explored the distribution of three brain-expressed FABPs, FABP 3, 5 and 7, by comparing three animal groups--infantile, normal and postischemic adult monkeys. Immunoblotting analysis revealed intense expression of FABP 3 and 7, but not of FABP5, in the control and postischemic adult cerebellum. The protein levels of FABP7, but not of FABP 3 or 5, gradually increased until 2 weeks after the insult. Immunohistochemical analysis showed that cerebellar FABP3-positive cells were Purkinje cells and Bergmann glia. FABP5-positive cells were found only in the postischemic cerebellum, and were identified as activated microglia. Interestingly, in the infantile cerebellum, both the granule cell progenitors in the external granular layer (EGL) and the oligodendrocyte progenitors in the internal granular layer (IGL) expressed FABP5. In the adult cerebellum, FABP7 was expressed in Purkinje cells and basket interneurons, while in the infantile cerebellum it was also found in Bergmann glia. These results showed differential expression of FABPs in cerebellar neuronal and glial cell types; FABP 3 and 7 were predominantly expressed in normal cerebellum, FABP5 after ischemic injury, while FABP 3, 5 and 7 were expressed during cerebellar development.

Omega-3 and omega-6 fatty acids suppress ER- and oxidative stress in cultured neurons and neuronal progenitor cells from mice lacking PPT1

Reactive oxygen species (ROS) damage brain lipids, carbohydrates, proteins, as well as DNA and may contribute to neurodegeneration. We previously reported that ER- and oxidative stress cause neuronal apoptosis in infantile neuronal ceroid lipofuscinosis (INCL), a lethal neurodegenerative storage disease, caused by palmitoyl-protein thioesterase-1 (PPT1) deficiency. Polyunsaturated fatty acids (PUFA) are essential components of cell membrane phospholipids in the brain and excessive ROS may cause oxidative damage of PUFA leading to neuronal death. Using cultured neurons and neuroprogenitor cells from mice lacking Ppt1, which mimic INCL, we demonstrate that Ppt1-deficient neurons and neuroprogenitor cells contain high levels of ROS, which may cause peroxidation of PUFA and render them incapable of providing protection against oxidative stress. We tested whether treatment of these cells with omega-3 or omega-6 PUFA protects the neurons and neuroprogenitor cells from oxidative stress and suppress apoptosis. We report here that both omega-3 and omega-6 fatty acids protect the Ppt1-deficient cells from ER- as well as oxidative stress and suppress apoptosis. Our results suggest that PUFA supplementation may have neuroprotective effects in INCL.

Hypertension induced by omega-3 polyunsaturated fatty acid deficiency is alleviated by alpha-linolenic acid regardless of dietary source

Omega-3 polyunsaturated fatty acid deficiency, particularly during the prenatal period, can cause hypertension in later life. This study examined the effect of different sources of alpha-linolenic acid (canola oil or flaxseed oil) in the prevention of hypertension and other metabolic symptoms induced by an omega-3 fatty acid-deficient diet. Dams were provided one of three experimental diets from 1 week before mating. Diets were either deficient (10% safflower oil-DEF) or sufficient (7% safflower oil+3% flaxseed oil-SUF-F; or 10% canola oil-SUF-C) in omega-3 fatty acids. The male offspring were continued on the maternal diet from weaning for the duration of the study. Body weight, ingestive behaviors, blood pressure, body composition, metabolic rate, plasma leptin and brain fatty acids were all assessed. The DEF animals were hypertensive at 24 weeks of age compared with SUF-F or SUF-C animals; this was not evident at 12 weeks. These results suggest that different sources of ALA are effective in preventing hypertension related to omega-3 fatty acid deficiency. However, there were other marked differences between the DEF and, in particular, the SUF-C phenotype including lowered body weight, adiposity, leptin and food intake in SUF-C animals. SUF-F animals also had lower, but less marked reductions in adiposity and leptin compared with DEF animals. The differences observed between DEF, SUF-F and SUF-C phenotypes indicate that body fat and leptin may be involved in omega-3 fatty acid deficiency hypertension.