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

N-3 Polyunsaturated Fatty Acids through the Lifespan: Implication for Psychopathology

OBJECTIVE

The impact of lifetime dietary habits and their role in physical, mental, and social well-being has been the focus of considerable recent research. Omega-3 polyunsaturated fatty acids as a dietary constituent have been under the spotlight for decades. Omega-3 polyunsaturated fatty acids constitute key regulating factors of neurotransmission, neurogenesis, and neuroinflammation and are thereby fundamental for development, functioning, and aging of the CNS. Of note is the fact that these processes are altered in various psychiatric disorders, including attention deficit hyperactivity disorder, depression, and Alzheimer's disease.

DESIGN

Relevant literature was identified through a search of MEDLINE via PubMed using the following words, "n-3 PUFAs," "EPA," and "DHA" in combination with "stress," "cognition," "ADHD," "anxiety," "depression," "bipolar disorder," "schizophrenia," and "Alzheimer." The principal focus was on the role of omega-3 polyunsaturated fatty acids throughout the lifespan and their implication for psychopathologies. Recommendations for future investigation on the potential clinical value of omega-3 polyunsaturated fatty acids were examined.

RESULTS

The inconsistent and inconclusive results from randomized clinical trials limits the usage of omega-3 polyunsaturated fatty acids in clinical practice. However, a body of literature demonstrates an inverse correlation between omega-3 polyunsaturated fatty acid levels and quality of life/ psychiatric diseases. Specifically, older healthy adults showing low habitual intake of omega-3 polyunsaturated fatty acids benefit most from consuming them, showing improved age-related cognitive decline.

CONCLUSIONS

Although further studies are required, there is an exciting and growing body of research suggesting that omega-3 polyunsaturated fatty acids may have a potential clinical value in the prevention and treatment of psychopathologies.

Dietary DHA and health: cognitive function ageing

DHA is a key nutritional n-3 PUFA and needs to be supplied by the human diet. DHA is found in significant amounts in the retinal and neuronal cell membranes due to its high fluidity. Indeed, DHA is selectively concentrated in the synaptic and retinal membranes. DHA is deemed to display anti-inflammatory properties and to reduce the risk of CVD. Consumption of larger amounts of DHA appears to reduce the risk of depression, bipolar disorder, schizophrenia and mood disorders. Conversely, it has been shown that loss of DHA from the nerve cell membrane leads to dysfunction of the central nervous system in the form of anxiety, irritability, susceptibility to stress, dyslexia, impaired memory and cognitive functions, and extended reaction times. DHA plays an important role in ensuring a healthy ageing, by thwarting macular degeneration, Alzheimer's disease, and other brain disorders at the same time as enhancing memory and strengthening neuroprotection in general. A reduced level of DHA is associated with cognitive decline during ageing. Different mechanisms for this fundamental DHA role have been put forward. Namely, neuroprotectin D1, a DHA derivative, may support brain cell survival and repair through neurotrophic, anti-apoptotic, and anti-inflammatory signalling. Many of the effects of DHA on the neurological system may be related to signalling connections, thus leading to the study of the related signalolipidomics. Therefore, the present review will focus on the influence of DHA deficiency upon ageing, with specific emphasis upon neurological disorders related to cognitive function and mental health.

Neuroprotective Effect of Several Phytochemicals and Its Potential Application in the Prevention of Neurodegenerative Diseases

The detrimental effects of oxidative stress and chronic neuroinflammation on neuronal cell death have been implicated in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD) and Parkinson's disease (PD). The nutritional neuroscience is quickly growing, and phytochemicals or phytobioactive compounds such as curcumin, resveratrol, propolis, ginsenoside, and ω-3 polyunsaturated fatty acids (PUFAs) have been extensively applied to potential therapeutic purposes for numerous neurodegenerative diseases for their anti-oxidative and anti-inflammatory effects. However, their administration as food supplements in the daily diet of the elderly is normally a voluntary and less-organized behavior, indicating the uncertainty of therapeutic effects in this sporadic population; specifically, the effective physiological dosages and the real positive effects in preserving brain health have not yet been fully elucidated. In this review, we collect several lines of evidence on these compounds, which constitute a major type of nutraceuticals and are widely integrated into the daily anti-aging caring of elderly patients, and discuss the underlying anti-oxidative and anti-inflammatory mechanisms of these phytochemicals. In conclusion, we highlight the implications of these compounds in the prevention and treatment of geriatric diseases, and of the potential supplementation procedures used as a dietary therapeutic program in clinical nursing services for patients with neurodegenerative diseases or for the elderly in certain communities, which we hope will lead to more beneficial health outcomes with respect to brain function, innate immunity, and gastrointestinal function, as well as more economic and social benefits.

Increased ω6-Containing Phospholipids and Primary ω6 Oxidation Products in the Brain Tissue of Rats on an ω3-Deficient Diet

Polyunsaturated fatty acyl (PUFA) chains in both the ω3 and ω6 series are essential for normal animal brain development, and cannot be interconverted to compensate for a dietary deficiency of one or the other. Paradoxically, a dietary ω3-PUFA deficiency leads to the accumulation of docosapentaenoate (DPA, 22:5ω6), an ω6-PUFA chain that is normally scarce in the brain. We applied a high-precision LC/MS method to characterize the distribution of DPA chains across phospholipid headgroup classes, the fatty acyl chains with which they were paired, and the extent to which they were oxidatively damaged in the cortical brain of rats on an ω3-deficient diet. Results indicate that dietary ω3-PUFA deficiency markedly increased the concentrations of phospholipids with DPA chains across all headgroup subclasses, including plasmalogen species. The concentrations of phospholipids containing docosahexaenoate chains (22:6ω3) decreased 20-25%, while the concentrations of phospholipids containing arachidonate chains (20:4ω6) did not change significantly. Although DPA chains are more saturated than DHA chains, a larger fraction of DPA chains were monohydroxylated, particularly among diacyl-phosphatidylethanolamines and plasmalogen phosphatidylethanolamines, suggesting that they were disproportionately subjected to oxidative stress. Differences in the pathological significance of ω3 and ω6 oxidation products suggest that greater oxidative damage among the ω6 PUFAs that increase in response to dietary ω3 deficiency may have pathological significance in Alzheimer's disease.

(-)Epigallocatechin-3-gallate prevents the reserpine-induced impairment of short-term social memory in rats

Reserpine has been confirmed to induce cognitive dysfunction and increase brain neural oxidative stress. Green tea catechins, particularly (-)epigallocatechin-3-gallate (EGCG), have strong antioxidative properties and can protect against numerous oxidative damages. In this study, we examined the possible protective effects of EGCG on reserpine-induced impairment of short-term memory in rats. Reserpine (1 mg/kg, intraperitoneal)-induced memory impairment was assessed using the social recognition task method; locomotor activity and the olfactory discrimination ability were not altered as measured by an open-field test and an olfactory discrimination test, respectively. EGCG treatment (100 and 300 mg/kg, intraperitoneal, for 7 days, starting 6 days before the reserpine injection) could improve the worsened social memory of reserpine-treated rats. Also, EGCG treatment reduced reserpine-induced lipid peroxidation and enhanced the antioxidation power in the hippocampi of reserpine-treated rats. These results suggest a protective effect of EGCG in treating reserpine-induced impairment of memory, most probably through its powerful antioxidative activities. Accordingly, EGCG may hold a clinically relevant value in preventing reserpine-induced cognitive dysfunction.

Omega 3 Fatty Acids: Novel Neurotherapeutic Targets for Cognitive Dysfunction in Mood Disorders and Schizophrenia?

An increasing body of evidences from preclinical as well as epidemiological and clinical studies suggest a potential beneficial role of dietary intake of omega-3 fatty acids for cognitive functioning. In this narrative review, we will summarize and discuss recent findings from epidemiological, interventional and experimental studies linking dietary consumption of omega-3 fatty acids to cognitive function in healthy adults. Furthermore, affective disorders and schizophrenia (SZ) are characterized by cognitive dysfunction encompassing several domains. Cognitive dysfunction is closely related to impaired functioning and quality of life across these conditions. Therefore, the current review focues on the potential influence of omega-3 fatty acids on cognition in SZ and affective disorders. In sum, current data predominantly from mechanistic models and animal studies suggest that adjunctive omega-3 fatty acid supplementation could lead to improved cognitive functioning in SZ and affective disorders. However, besides its translational promise, evidence for clinical benefits in humans has been mixed. Notwithstanding evidences indicate that adjunctive omega-3 fatty acids may have benefit for affective symptoms in both unipolar and bipolar depression, to date no randomized controlled trial had evaluated omega-3 as cognitive enhancer for mood disorders, while a single published controlled trial suggested no therapeutic benefit for cognitive improvement in SZ. Considering the pleiotropic mechanisms of action of omega-3 fatty acids, the design of well-designed controlled trials of omega-3 supplementation as a novel, domain-specific, target for cognitive impairment in SZ and affective disorders is warranted.

Lutein protects against ischemia/reperfusion injury in rat skeletal muscle by modulating oxidative stress and inflammation

BACKGROUND

Lutein is an antioxidant compound with potential biological effects. The present study investigated the protective role of Lutein against I/R injury in skeletal muscle.

METHODS

Animals were divided into three groups. Group I - sham operated; Group II- IR injury- Hind limb ischemia was induced by clamping the common femoral artery and vein. After 4 h of ischemia, the clamp was removed and the animals underwent 2 h of reperfusion. Group III-Lutein + IR injury- Rats with Lutein treatment received intraperitoneal injection 1 h before reperfusion. The skeletal tissues were analyzed for oxidative stress parameters (reactive oxygen species, protein carbonylation and sulfhydryls, lipid peroxidation). Antioxidant status was determined by evaluating Nrf-2 levels and antioxidant enzyme activities. The inflammatory mechanism was determined through NF-κB and COX-2 expressions. Pro-inflammatory cytokines were determined by ELISA.

RESULTS

The results showed that Lutein treatment significantly decreased the oxidative stress by reducing reactive oxygen species, protein carbonylation and sulphydryls, lipid peroxidation. Further, the levels of Nrf-2 and antioxidant status was significantly declined during IR injury compared to sham operated rats. Lutein treatment reduced the oxidative stress by enhancing Nrf-2 levels and antioxidant status. Skeletal IR injury enhanced the inflammatory signaling by up regulating NF-κB, COX-2 and various pro-inflammatory cytokines. NF-κB, COX-2 expressions were down regulated by Lutein treatment.

CONCLUSION

The study shows that Lutein protects against skeletal IR injury by down regulating oxidative stress and inflammatory mechanisms.

Plumbagin Mediates Cardioprotection Against Myocardial Ischemia/Reperfusion Injury Through Nrf-2 Signaling

Background

Plumbagin is a potent antioxidant with anti-inflammatory and anti-carcinogenic action. Myocardial ischemia/reperfusion injury results in organ damage through oxidative stress and inflammatory mechanisms. In this study, we analyzed the potential role of plumbagin against myocardial I/R injury in Wistar rats.

Material/Methods

Oxidative stress was measured through ROS, lipid peroxide content, and antioxidant enzyme activities. The expression of redox signaling and inflammatory proteins was analyzed through Western blotting. Inflammatory cytokine expressions were determined through ELISA.

Results

Oxidative stress status was reduced by plumbagin by decreasing ROS and lipid peroxide levels in rats with myocardial I/R (MI/R) injury. Plumbagin regulated redox imbalance induced by I/R injury by modulating the transcription factors NF-κB and Nrf-2. Further, downstream targets of NF-κB (COX-2, iNOS) and Nrf-2 (HO-1, NQO1 and GST) expression were significantly downregulated by plumbagin treatment. Pro-inflammatory cytokine expressions were significantly abrogated by plumbagin treatment.

Conclusions

This study shows the protective role of plumbagin against myocardial I/R injury by regulating antioxidant and inflammatory mechanisms.

Eicosapentaenoic acid and docosahexaenoic acid increase the degradation of amyloid-β by affecting insulin-degrading enzyme

Omega-3 polyunsaturated fatty acids (PUFAs) have been proposed to be highly beneficial in Alzheimer's disease (AD). AD pathology is closely linked to an overproduction and accumulation of amyloid-β (Aβ) peptides as extracellular senile plaques in the brain. Total Aβ levels are not only dependent on its production by proteolytic processing of the amyloid precursor protein (APP), but also on Aβ-clearance mechanisms, including Aβ-degrading enzymes. Here we show that the omega-3 PUFAs eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) increase Aβ-degradation by affecting insulin-degrading enzyme (IDE), the major Aβ-degrading enzyme secreted into the extracellular space of neuronal and microglial cells. The identification of the molecular mechanisms revealed that EPA directly increases IDE enzyme activity and elevates gene expression of IDE. DHA also directly stimulates IDE enzyme activity and affects IDE sorting by increasing exosome release of IDE, resulting in enhanced Aβ-degradation in the extracellular milieu. Apart from the known positive effect of DHA in reducing Aβ production, EPA and DHA might ameliorate AD pathology by increasing Aβ turnover.

Dietary Crude Lecithin Increases Systemic Availability of Dietary Docosahexaenoic Acid with Combined Intake in Rats

Crude lecithin, a mixture of mainly phospholipids, potentially helps to increase the systemic availability of dietary omega-3 polyunsaturated fatty acids (n-3 PUFA), such as docosahexaenoic acid (DHA). Nevertheless, no clear data exist on the effects of prolonged combined dietary supplementation of DHA and lecithin on RBC and plasma PUFA levels. In the current experiments, levels of DHA and choline, two dietary ingredients that enhance neuronal membrane formation and function, were determined in plasma and red blood cells (RBC) from rats after dietary supplementation of DHA-containing oils with and without concomitant dietary supplementation of crude lecithin for 2–3 weeks. The aim was to provide experimental evidence for the hypothesized additive effects of dietary lecithin (not containing any DHA) on top of dietary DHA on PUFA levels in plasma and RBC. Dietary supplementation of DHA-containing oils, either as vegetable algae oil or as fish oil, increased DHA, eicosapentaenoic acid (EPA), and total n-3 PUFA, and decreased total omega-6 PUFA levels in plasma and RBC, while dietary lecithin supplementation alone did not affect these levels. However, combined dietary supplementation of DHA and lecithin increased the changes induced by DHA supplementation alone. Animals receiving a lecithin-containing diet also had a higher plasma free choline concentration as compared to controls. In conclusion, dietary DHA-containing oils and crude lecithin have synergistic effects on increasing plasma and RBC n-3 PUFA levels, including DHA and EPA. By increasing the systemic availability of dietary DHA, dietary lecithin may increase the efficacy of DHA supplementation when their intake is combined.

The pleiotropic effects of omega-3 docosahexaenoic acid on the hallmarks of Alzheimer's disease

Among omega-3 polyunsaturated fatty acids (PUFAs), docosahexaenoic acid (DHA, 22:6n-3) is important for adequate brain development and cognition. DHA is highly concentrated in the brain and plays an essential role in brain functioning. DHA, one of the major constituents in fish fats, readily crosses the blood-brain barrier from blood to the brain. Its critical role was further supported by its reduced levels in the brain of Alzheimer's disease (AD) patients. This agrees with a potential role of DHA in memory, learning and cognitive processes. Since there is yet no cure for dementia such as AD, there is growing interest in the role of DHA-supplemented diet in the prevention of AD pathogenesis. Accordingly, animal, epidemiological, preclinical and clinical studies indicated that DHA has neuroprotective effects in a number of neurodegenerative conditions including AD. The beneficial effects of this key omega-3 fatty acid supplementation may depend on the stage of disease progression, other dietary mediators and the apolipoprotein ApoE genotype. Herein, our review investigates, from animal and cell culture studies, the molecular mechanisms involved in the neuroprotective potential of DHA with emphasis on AD.

Nitric oxide pathway activity modulation alters the protective effects of (-)Epigallocatechin-3-gallate on reserpine-induced impairment in rats

Reserpine (RES) has been reported to increase the brain's neural oxidative stress and cause cognitive dysfunction. Having powerful antioxidative properties, green tea catechins, especially (-)epigallocatechin-3-gallate (EGCG), are able to protect against many oxidative injuries. In this study, we examined the protecting properties of EGCG on RES-induced impairment of short-term memory in three-month-old male Wistar rats. RES (1mg/kg i.p.) induced memory impairment (p<0.001) as evaluated by the social recognition task. EGCG treatment (100mg/kg i.p. for 7days, starting 6days before RES injection) was able to improve the impaired memory caused by RES. RES treatment increased the nitric oxide (NO) level and lipid peroxidation (LPO) production, and decreased the antioxidation power in hippocampi. EGCG treatment was able to counteract the RES-induced NO level and LPO production, as well as enhanced the hippocampal antioxidation power in RES-treated rats. In order to examine the implication of NO pathway activity in RES treatment, either NO precursor (L-arginine; L-A) or NO synthase inhibitor (L-NAME; L-N) was co-pretreated with EGCG; NO precursor treatment eliminated the protective effect of EGCG, in contrast to that NO synthase inhibitor treatment significantly increased the EGCG effects on cognitive and biochemical protection in RES-treated rats. These results suggested that the NO pathway was implicated, at least in part, in the RES-induced impairment, as well as in the protective effect of EGCG in treating RES-induced impairment of memory. The above evidence provides a clinically relevant value for EGCG in preventing RES-induced cognitive dysfunction.

Beneficial effects of dietary docosahexaenoic acid intervention on cognitive function and mental health of the oldest elderly in Japanese care facilities and nursing homes

AIM

We examined the effects of the administration of docosahexaenoic acid (DHA)-enriched meals on cognitive function in the oldest elderly with cognitive impairment, such as dementia, living in nursing homes, and on the improvement in caregiver burden at aging agencies.

METHODS

Participants in elderly care facilities and nursing homes (n = 75; 88.5 ± 0.6 years) were randomized in active and placebo groups. The active group had family-style meals containing an additional 1720 mg of docosahexaenoic acid per day for 12 months. At baseline, and after 6 and 12 months of intervention, cognitive function was assessed using Hasegawa's Dementia Scale-Revised and the Mini-Mental State Examination; mental health condition was assessed with the Apathy scale and the Zung Self-Rating Depression Scale; caregiver burden was evaluated using Zarit Burden Interview scores; and participants' serum biochemical factors were measured.

RESULTS

The participants were suggested to have dementia. After 12 months, the mean change in Mini-Mental State Examination subitem "Registration" score from baseline to month 12 showed a tendency to be greater in the active group than that in the placebo group. Mean changes in the Apathy scale from baseline to month 12 were less, and the changes in the Zung Self-Rating Depression Scale and the total Zarit Burden Interview scores showed a tendency to be lower in the active group than in the placebo group, respectively.

CONCLUSION

These results suggest that docosahexaenoic acid-enriched meals protect against age-related cognitive decline, and also improve apathy and caregiver burden for the oldest-elderly Japanese with cognitive impairment, such as dementia. Geriatr Gerontol Int 2017; 17: 330-337.

Novel promising therapeutics against chronic neuroinflammation and neurodegeneration in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder, characterized by deposition of amyloid plaques and neurofibrillary tangles, as well as microglial and astroglial activation, and, finally, leading to neuronal dysfunction and death. Current treatments for AD primarily focus on enhancement of cholinergic transmission. However, these treatments are only symptomatic, and no disease-modifying drug is available for the treatment of AD patients. This review will provide an overview of the antioxidant, anti-inflammatory, anti-amyloidogenic, neuroprotective, and cognition-enhancing effects of a variety of nutraceuticals including curcumin, apigenin, docosahexaenoic acid, epigallocatechin gallate, α-lipoic acid and resveratrol and their potential for AD prevention and treatment. We suggest that therapeutic use of these compounds might lead to a safe strategy to delay the onset of AD or slow down its progression. The continuing investigation of the potential of these substances is necessary as they are promising compounds to yield a possible remedy for this pervasive disease.

Chronic Arachidonic Acid Administration Decreases Docosahexaenoic Acid- and Eicosapentaenoic Acid-Derived Metabolites in Kidneys of Aged Rats

Arachidonic acid (ARA) metabolites produced by cyclo-oxygenase and lipoxygenase are important mediators maintaining physiological renal function. However, the effects of exogenous ARA on kidney function in vivo remain unknown. This study examined the effects of long-term oral ARA administration on normal renal function as well as inflammation and oxidative stress in aged rats. In addition, we measured levels of renal eicosanoids and docosanoids using liquid chromatography–tandem mass spectrometry. Control or ARA oil (240 mg/kg body weight/day) was orally administered to 21-month-old Wistar rats for 13 weeks. Levels of plasma creatinine, blood urea nitrogen, inflammatory and anti-inflammatory cytokines, reactive oxygen species, and lipid peroxidation were not significantly different between the two groups. The ARA concentration in the plasma, kidney, and liver increased in the ARA-administered group. In addition, levels of free-form ARA, prostaglandin E₂, and 12- and 15-hydroxyeicosatetraenoic acid increased in the ARA-administered group, whereas renal concentration of docosahexaenoic acid and eicosapentaenoic acid decreased in the ARA-administered group. Levels of docosahexaenoic acid-derived protectin D1, eicosapentaenoic acid-derived 5-, and 18-hydroxyeicosapentaenoic acids, and resolvin E2 and E3 decreased in the ARA-administered group. Our results indicate that long-term ARA administration led to no serious adverse reactions under normal conditions and to a decrease in anti-inflammatory docosahexaenoic acid- and eicosapentaenoic acid-derived metabolites in the kidneys of aged rats. These results indicate that there is a possibility of ARA administration having a reducing anti-inflammatory effect on the kidney.

Long-Term Dietary Alpha-Linolenic Acid Supplement Alleviates Cognitive Impairment Correlate with Activating Hippocampal CREB Signaling in Natural Aging Rats

Alpha-linolenic acid (ALA) is a major precursor of the essential n-3 polyunsaturated fatty acid (PUFA), whose deficiency alters the structure and function of membranes and induces cerebral dysfunctions. The major purpose of this study was to investigate the protective effect of prolonged ALA intake on cognitive function during natural aging. Female Sprague-Dawley rats aged 6 months were chronically treated with ALA and/or lard per day for 12 months. Regular diet-treated rats, both young and old (4 and 18 months old, respectively) served as controls. Rats fed on regular diet during aging showed memory deficits in Morris water maze, which were further exacerbated by lard intake. However, supplementation with ALA for 12 months dose-dependently improved the performance in spatial working memory tasks. Memory performance correlated well with the activation of cAMP response element-binding protein (CREB) and increases in both levels of brain-derived neurotrophic factor (BDNF) and its specific receptor tyrosine kinase B (TrkB) phosphorylation in the hippocampus. Further study identified that hippocampal extracellular signal-related kinase (ERK) and Akt rather than calcium calmodulin kinase IV (CaMKIV) and protein kinase A (PKA), the upstream signalings of CREB, were also activated by ALA supplement. Moreover, memory improvement was accompanied with alterations of hippocampal synaptic structure and number, suggestive of enhancement in synaptic plasticity. Together, these results suggest that long-term dietary intake of ALA enhances CREB/BDNF/TrkB pathway through the activation of ERK and Akt signalings in hippocampus, which contributes to its ameliorative effects on cognitive deficits in natural aging.

Light, lipids and photoreceptor survival: live or let die?

Due to its constant exposure to light and its high oxygen consumption the retina is highly sensitive to oxidative damage, which is a common factor in inducing the death of photoreceptors after light damage or in inherited retinal degenerations. The high content of docosahexaenoic acid (DHA), the major polyunsaturated fatty acid in the retina, has been suggested to contribute to this sensitivity. DHA is crucial for developing and preserving normal visual function. However, further roles of DHA in the retina are still controversial. Current data support that it can tilt the scale either towards degeneration or survival of retinal cells. DHA peroxidation products can be deleterious to the retina and might lead to retinal degeneration. However, DHA has also been shown to act as, or to be the source of, a survival molecule that protects photoreceptors and retinal pigment epithelium cells from oxidative damage. We have established that DHA protects photoreceptors from oxidative stress-induced apoptosis and promotes their differentiation in vitro. DHA activates the retinoid X receptor (RXR) and the ERK/MAPK pathway, thus regulating the expression of anti and pro-apoptotic proteins. It also orchestrates a diversity of signaling pathways, modulating enzymatic pathways that control the sphingolipid metabolism and activate antioxidant defense mechanisms to promote photoreceptor survival and development. A deeper comprehension of DHA signaling pathways and context-dependent behavior is required to understand its dual functions in retinal physiology.

Carnosol protects against spinal cord injury through Nrf-2 upregulation

BACKGROUND

Carnosol is an ortho-diphenolic diterpene with excellent antioxidant potential. The present study was designed to identify the protective role of carnosol against spinal cord injury (SCI)-induced oxidative stress and inflammation in Wistar rats.

METHODS

In the present study, oxidative stress status was determined through estimating total antioxidant capacity, total oxidant status, lipid peroxide content, protein carbonyl and sulfhydryl levels, reactive oxygen species (ROS), antioxidant status (superoxide-dismutase, catalase, glutathione, glutathione peroxidase, glutathione-S-transferase). Inflammatory effects were determined by analyzing the expression of NF-κB and COX-2 through Western blot analysis. Further, carnosol-mediated redox homeostasis was analyzed by determining p-AKT and Nrf-2 levels.

RESULTS

SCI resulted in a significant increase in oxidative stress status through increased ROS generation, total oxidant levels, lipid peroxide content, protein carbonyl and sulfhydryl levels. The antioxidant status in SCI rats was significantly reduced, indicating imbalance in redox status. In addition, the expression of NF-κB and COX-2 was significantly upregulated, while p-AKT and Nrf-2 levels were downregulated in SCI rats. However, treatment with carnosol showed a significant enhancement in the antioxidant status with concomitant decline in oxidative stress parameters. Further, carnosol treatment regulated the key proteins in inflammation and redox status through significant downregulation of NF-κB and COX-2 levels and upregulation of p-AKT and Nrf-2 expression.

CONCLUSION

Thus, the present study shows for the first time on the protective role of carnosol against SCI-induced oxidative stress and inflammation through modulating NF-κB, COX-2 and Nrf-2 levels in Wistar rats.

Attenuation of lead neurotoxicity by supplementation of polyunsaturated fatty acid in Wistar rats

BACKGROUND

Among various types of polyunsaturated fatty acid (PUFA), omega-3 fatty acids play a crucial role in development and function of the brain. This study was undertaken to investigate the possible neuroprotective efficacy of omega-3 fatty acid on lead-induced neurotoxicity in rats.

MATERIAL AND METHODS

The experiment was carried out on 32 male Wistar rats divided into four groups. The first group (control) was treated with distilled water and second group with lead acetate at the doses of 3 mg/kg b.wt. (body weight)/oral, whereas third and fourth groups were simultaneously treated with lead acetate (3 mg/kg b.wt.) plus omega-3 fatty acid (300 mg/kg b.wt./oral) and lead acetate (3 mg/kg b.wt.) plus vitamin E (100 mg/kg b.wt./oral), respectively, for a period of 90 days. Their biochemical and histopathological investigations have been carried out.

RESULTS

The level of lead was markedly elevated in brain (4.71-fold) and blood (5.65-fold), also increased levels of ROS, GSH, LPO with concomitant reduction in the activities of delta-ALAD, CAT, SOD, and GPx. In addition, lead-induced brain damage was indicated by histopathological changes. Omega-3 fatty acid resulted in marked improvement in most of the biochemical parameters as well as histopathological changes in rats. The results obtained were compared with vitamin E as the standard antioxidant agents.

DISCUSSION

Omega-3 fatty acid significantly (P < 0.05) decreased the effect of lead-induced brain damage as well as biochemical changes similar to that of standard drug, vitamin E. So, our result suggested that omega-3 fatty acid may play a protective role in lead-induced neurotoxicity and associated human health risk.

Effect of long-term administration of arachidonic acid on n-3 fatty acid deficient mice

The effect of long-term oral administration of arachidonic acid (ARA, 240 mg/kg/day) on brain function was assessed for mice maintained on an n-3 fatty acid adequate or deficient diet. The administration of ARA for 13 weeks resulted in an elevation of spontaneous motor activity, or the tendency thereof, in both the n-3 fatty acid adequate and deficient groups. However, the n-3 fatty acid deficient mice that were administered with ARA revealed marked deterioration in motor function in a motor coordination test. In the experiment to investigate changes over time, the motor activity of the ARA-administered group continued to increase mildly in n-3 deficient mice, although that of the control group showed a decrease involving habituation for both diet groups from the second week. The fatty acid composition of the brain at the end of the behavioral experiments indicated an increase in the levels of ARA and other n-6 fatty acids, as well as a decrease in the levels of docosahexaenoic acid. These results suggest that long-term administration of ARA causes an increase of futile spontaneous motor activity and the diminution of motor function by aggravation of n-3 fatty acid deficiency.

(-) Epigallocatechin-3-gallate attenuates reserpine-induced orofacial dyskinesia and oxidative stress in rat striatum

Reserpine-induced orofacial dyskinesia (OD) has been used for decades as an animal model for human tardive dyskinesia (TD) because both of them have pathophysiology strongly associated with striatal oxidative stress. Green tea catechins, especially (-) epigallocatechin-3-gallate (EGCG), have potent antioxidative effects and are able to protect against various oxidative injuries. In this study, we examined the potential protective effects of EGCG on reserpine-induced behavioral and neurochemical dysfunction in rats. Reserpine treatment (1mg/kgs.c. one injection every other day, three injections total) induced significant increases (p<0.001) in the frequency of vacuous chewing movement (VCM) and tongue protrusion (TP) as well as the duration of facial twitching (FT). EGCG treatment (100mg/kgi.p. for 11days, starting 7days before the reserpine injections) was able to prevent most of the reserpine-induced OD. Also, EGCG treatment was able to reduce the reserpine-induced lipid peroxidation (LPO) production, and enhances the antioxidation power in the striatum of reserpine-treated rats. The above results indicate that EGCG has a protective role against reserpine-induced OD, probably via its powerful antioxidative properties. Thus, EGCG may possible have a clinically relevant therapeutic effect in preventing, delaying or even treating TD.

Dietary factors in the etiology of Parkinson's disease

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

Impact of DHA on metabolic diseases from womb to tomb

Long chain polyunsaturated fatty acids (LC-PUFAs) are important mediators in improving and maintaining human health over the total lifespan. One topic we especially focus on in this review is omega-3 LC-PUFA docosahexaenoic acid (DHA). Adequate DHA levels are essential during neurodevelopment and, in addition, beneficial in cognitive processes throughout life. We review the impact of DHA on societal relevant metabolic diseases such as cardiovascular diseases, obesity, and diabetes mellitus type 2 (T2DM). All of these are risk factors for cognitive decline and dementia in later life. DHA supplementation is associated with a reduced incidence of both stroke and atherosclerosis, lower bodyweight and decreased T2DM prevalence. These findings are discussed in the light of different stages in the human life cycle: childhood, adolescence, adulthood and in later life. From this review, it can be concluded that DHA supplementation is able to inhibit pathologies like obesity and cardiovascular disease. DHA could be a dietary protector against these metabolic diseases during a person’s entire lifespan. However, supplementation of DHA in combination with other dietary factors is also effective. The efficacy of DHA depends on its dose as well as on the duration of supplementation, sex, and age.

n-3 fatty acids effectively improve the reference memory-related learning ability associated with increased brain docosahexaenoic acid-derived docosanoids in aged rats

We investigated whether a highly purified eicosapentaenoic acid (EPA) and a concentrated n-3 fatty acid formulation (prescription TAK-085) containing EPA and docosahexaenoic acid (DHA) ethyl ester could improve the learning ability of aged rats and whether this specific outcome had any relation with the brain levels of EPA-derived eicosanoids and DHA-derived docosanoids. The rats were tested for reference memory errors (RMEs) and working memory errors (WMEs) in an eight-arm radial maze. Fatty acid compositions were analyzed by GC, whereas brain eicosanoid/docosanoids were measured by LC-ESI-MS-MS-based analysis. The levels of lipid peroxides (LPOs) were measured by thiobarbituric acid reactive substances. The administration of TAK-085 at 300 mg·kg⁻¹day⁻¹ for 17 weeks reduced the number of RMEs in aged rats compared with that in the control rats. Both TAK-085 and EPA administration increased plasma EPA and DHA levels in aged rats, with concurrent increases in DHA and decreases in arachidonic acid in the corticohippocampal brain tissues. TAK-085 administration significantly increased the formation of EPA-derived 5-HETE and DHA-derived 7-, 10-, and 17-HDoHE, PD1, RvD1, and RvD2. ARA-derived PGE2, PGD2, and PGF2α significantly decreased in TAK-085-treated rats. DHA-derived mediators demonstrated a significantly negative correlation with the number of RMEs, whereas EPA-derived mediators did not exhibit any relationship. Furthermore, compared with the control rats, the levels of LPO in the plasma, cerebral cortex, and hippocampus were significantly reduced in TAK-085-treated rats. The findings of the present study suggest that long-term EPA+DHA administration may be a possible preventative strategy against age-related cognitive decline.

Protective effects of Vitamin C against spinal cord injury-induced renal damage through suppression of NF-κB and proinflammatory cytokines

Spinal cord injury [SCI] leads to complex cellular and molecular interactions which affects various organ systems. The present study focused on determining the protection offered by Vitamin C against spinal injury-induced kidney damage in wistar rats. The experimental protocol was performed with three groups; Sham, SCI and Vitamin C [20 mg/kg/bw] followed by SCI. The kidney tissue was investigated for oxidative stress parameters [reactive oxygen species, protein carbonyl, sulphydryl content, thiobarbituric acid reactive species [TBARS], and myeloperoxidase activity] and antioxidant status [glutathione, superoxide dismutase, catalase, glutathione peroxidase, glutathione-S-transferase activity]. Further, inflammation studies were performed by analyzing expression of NF-κB, cycloxygenase-2, iNOS through western blot analysis and inflammatory cytokines by TNF-α and IL-1β levels. The present study shows clear evidence that Vitamin C treatment abrogated spinal injury-induced oxidative stress and inflammatory responses and enhanced the antioxidant status. Thus, the protection offered by Vitamin C against spinal cord injury-induced kidney damage is attributed to its anti-oxidant and anti-inflammatory effects.

Maternal omega-3 fatty acid supplementation on vitamin B12 rich diet improves brain omega-3 fatty acids, neurotrophins and cognition in the Wistar rat offspring

INTRODUCTION

The consequences of wide spread vegetarianism due to low vitamin B12 on brain development and functioning is gaining importance. However, there are no studies which have evaluated exclusively vitamin B12 supplementation during pregnancy on brain growth. A series of our animal studies have documented adverse effects of maternal micronutrient imbalance on brain neurotrophins and its amelioration by omega-3 fatty acids. Therefore, the present study investigated the effect of maternal supplementation with vitamin B12 alone and B12 plus omega-3 fatty acid on pup brain fatty acids and neurotrophins at birth and 3 mo of age.

METHODS AND RESULTS

Pregnant Wistar rats and their male offspring were assigned to 3 dietary groups: Control (normal vitamin B12 (25 μg/kg), vitamin B12 supplemented (BS) (50 μg/kg), vitamin B12 supplemented with omega-3 fatty acid (BSO) till 3 month of age. Maternal vitamin B12 supplementation (BS) increased brain BDNF (protein and mRNA) and DHA levels in pups at birth and in the hippocampus at 3 month of age (BDNF only). These effects were further enhanced by omega-3 fatty acid supplementation to vitamin B12 supplemented group. The spatial memory performance was found to be enhanced in BSO group which was characterised by less number of errors in radial eight arm maze.

CONCLUSION

Our results indicate that a combination of omega-3 fatty acid and vitamin B12 enriched diet may exert beneficial effects on synaptic plasticity and cognition, which may prove beneficial for mental health, particularly in preventing neurocognitive disorders.

Effects of omega-3 on behavioral and biochemical parameters in rats submitted to chronic mild stress

Major depression is a heterogeneous psychiatric disorder whose pathophysiology is not clearly established yet. Some studies have shown that oxidative stress and mitochondrial dysfunction are involved in the development of major depression. Since most depressed patients do not achieve complete remission of symptoms, new therapeutic alternatives are needed and omega-3 has been highlighted in this scenario. Therefore, we have investigated the effects of omega-3 on behavioral and biochemical parameters in rats submitted to chronic mild stress (CMS). Male Wistar rats were submitted to CMS for 40 days. After the CMS period, we administered a 500 mg/kg dose of omega-3 orally, once a day, for 7 days. The animals submitted to CMS presented anhedonia, had no significant weight gain, presented increased levels of lipid peroxidation and protein carbonylation, and inhibition of complex I and IV activities of the mitochondrial respiratory chain. The treatment with omega-3 did not reverse anhedonia; however, it reversed weight change, increased lipid peroxidation and protein carbonylation levels, and partially reversed the inhibition of mitochondrial respiratory chain complexes. The findings support studies that state that major depression is associated with mitochondrial dysfunction and oxidative stress, and that omega-3 supplementation could reverse some of these changes, probably due to its antioxidant properties.

Supplemental substances derived from foods as adjunctive therapeutic agents for treatment of neurodegenerative diseases and disorders

Neurodegenerative disorders and diseases (NDDs) that are either chronically acquired or triggered by a singular detrimental event are a rapidly growing cause of disability and/or death. In recent times, there have been major advancements in our understanding of various neurodegenerative disease states that have revealed common pathologic features or mechanisms. The many mechanistic parallels discovered between various neurodegenerative diseases suggest that a single therapeutic approach may be used to treat multiple disease conditions. Of late, natural compounds and supplemental substances have become an increasingly attractive option to treat NDDs because there is growing evidence that these nutritional constituents have potential adjunctive therapeutic effects (be it protective or restorative) on various neurodegenerative diseases. Here we review relevant experimental and clinical data on supplemental substances (i.e., curcuminoids, rosmarinic acid, resveratrol, acetyl-L-carnitine, and ω-3 (n-3) polyunsaturated fatty acids) that have demonstrated encouraging therapeutic effects on chronic diseases, such as Alzheimer's disease and neurodegeneration resulting from acute adverse events, such as traumatic brain injury.

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

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

Transfer of omega-3 fatty acids across the blood-brain barrier after dietary supplementation with a docosahexaenoic acid-rich omega-3 fatty acid preparation in patients with Alzheimer's disease: the OmegAD study

OBJECTIVE

Little is known about the transfer of essential fatty acids (FAs) across the human blood-brain barrier (BBB) in adulthood. In this study, we investigated whether oral supplementation with omega-3 (n-3) FAs would change the FA profile of the cerebrospinal fluid (CSF).

METHODS

A total of 33 patients (18 receiving the n-3 FA supplement and 15 receiving placebo) were included in the study. These patients were participants in the double-blind, placebo-controlled randomized OmegAD study in which 204 patients with mild Alzheimer's disease (AD) received 2.3 g n-3 FA [high in docosahexaenoic acid (DHA)] or placebo daily for 6 months. CSF FA levels were related to changes in plasma FA and to CSF biomarkers of AD and inflammation.

RESULTS

At 6 months, the n-3 FA supplement group displayed significant increases in CSF (and plasma) eicosapentaenoic acid (EPA), DHA and total n-3 FA levels (P < 0.01), whereas no changes were observed in the placebo group. Changes in CSF and plasma levels of EPA and n-3 docosapentaenoic acid were strongly correlated, in contrast to those of DHA. Changes in DHA levels in CSF were inversely correlated with CSF levels of total and phosphorylated tau, and directly correlated with soluble interleukin-1 receptor type II. Thus, the more DHA increased in CSF, the greater the change in CSF AD/inflammatory biomarkers.

CONCLUSIONS

Oral supplementation with n-3 FAs conferred changes in the n-3 FA profile in CSF, suggesting transfer of these FAs across the BBB in adults.

Neuroprotective properties of the marine carotenoid astaxanthin and omega-3 fatty acids, and perspectives for the natural combination of both in krill oil

The consumption of marine fishes and general seafood has long been recommended by several medical authorities as a long-term nutritional intervention to preserve mental health, hinder neurodegenerative processes, and sustain cognitive capacities in humans. Most of the neurological benefits provided by frequent seafood consumption comes from adequate uptake of omega-3 and omega-6 polyunsaturated fatty acids, n-3/n-6 PUFAs, and antioxidants. Optimal n-3/n-6 PUFAs ratios allow efficient inflammatory responses that prevent the initiation and progression of many neurological disorders. Moreover, interesting in vivo and clinical studies with the marine antioxidant carotenoid astaxanthin (present in salmon, shrimp, and lobster) have shown promising results against free radical-promoted neurodegenerative processes and cognition loss. This review presents the state-of-the-art applications of n-3/n-6 PUFAs and astaxanthin as nutraceuticals against neurodegenerative diseases associated with exacerbated oxidative stress in CNS. The fundamental “neurohormesis” principle is discussed throughout this paper. Finally, new perspectives for the application of a natural combination of the aforementioned anti-inflammatory and antioxidant agents (found in krill oil) are also presented herewith.

The emerging role of nutrition in Parkinson's disease

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease in ageing individuals. It is now clear that genetic susceptibility and environmental factors play a role in disease etiology and progression. Because environmental factors are involved with the majority of the cases of PD, it is important to understand the role nutrition plays in both neuroprotection and neurodegeneration. Recent epidemiological studies have revealed the promise of some nutrients in reducing the risk of PD. In contrast, other nutrients may be involved with the etiology of neurodegeneration or exacerbate disease progression. This review summarizes the studies that have addressed these issues and describes in detail the nutrients and their putative mechanisms of action in PD.

The influences of parental diet and vitamin E intake on the embryonic zebrafish transcriptome

The composition of the typical commercial diet fed to zebrafish can dramatically vary. By utilizing defined diets we sought to answer two questions: 1) How does the embryonic zebrafish transcriptome change when the parental adults are fed a commercial lab diet compared with a sufficient, defined diet (E+)? 2) Does a vitamin E-deficient parental diet (E-) further change the embryonic transcriptome? We conducted a global gene expression study using embryos from zebrafish fed a commercial (Lab), an E+ or an E- diet. To capture differentially expressed transcripts prior to onset of overt malformations observed in E- embryos at 48h post-fertilization (hpf), embryos were collected from each group at 36hpf. Lab embryos differentially expressed (p<0.01) 946 transcripts compared with the E+ embryos, and 2656 transcripts compared with the E- embryos. The differences in protein, fat and micronutrient intakes in zebrafish fed the Lab compared with the E+ diet demonstrate that despite overt morphologic consistency, significant differences in gene expression occurred. Moreover, functional analysis of the significant transcripts in the E- embryos suggested perturbed energy metabolism, leading to overt malformations and mortality. Thus, these findings demonstrate that parental zebrafish diet has a direct impact on the embryonic transcriptome.

Metabotyping of docosahexaenoic acid - treated Alzheimer's disease cell model

Background

Despite the significant amount of work being carried out to investigate the therapeutic potential of docosahexaenoic acid (DHA) in Alzheimer’s disease (AD), the mechanism by which DHA affects amyloid-β precursor protein (AβPP)-induced metabolic changes has not been studied.

Objective

To elucidate the metabolic phenotypes (metabotypes) associated with DHA therapy via metabonomic profiling of an AD cell model using gas chromatography time-of-flight mass spectrometry (GC/TOFMS).

Methods

The lysate and supernatant samples of CHO-wt and CHO-AβPP₆₉₅ cells treated with DHA and vehicle control were collected and prepared for GC/TOFMS metabonomics profiling. The metabolic profiles were analyzed by multivariate data analysis techniques using SIMCA-P+ software.

Results

Both principal component analysis and subsequent partial least squares discriminant analysis revealed distinct metabolites associated with the DHA-treated and control groups. A list of statistically significant marker metabolites that characterized the metabotypes associated with DHA treatment was further identified. Increased levels of succinic acid, citric acid, malic acid and glycine and decreased levels of zymosterol, cholestadiene and arachidonic acid correlated with DHA treatment effect. DHA levels were also found to be increased upon treatment.

Conclusion

Our study shows that DHA plays a role in mitigating AβPP-induced impairment in energy metabolism and inflammation by acting on tricarboxylic acid cycle, cholesterol biosynthesis pathway and fatty acid metabolism. The perturbations of these metabolic pathways by DHA in CHO-wt and CHO-AβPP₆₉₅ cells shed further mechanistic insights on its neuroprotective actions.

Prescription n-3 fatty acids, but not eicosapentaenoic acid alone, improve reference memory-related learning ability by increasing brain-derived neurotrophic factor levels in SHR.Cg-Lepr(cp)/NDmcr rats, a metabolic syndrome model

Metabolic syndrome is implicated in the decline of cognitive ability. We investigated whether the prescription n-3 fatty acid administration improves cognitive learning ability in SHR.Cg-Lepr(cp)/NDmcr (SHR-cp) rats, a metabolic syndrome model, in comparison with administration of eicosapentaenoic acid (EPA, C20:5, n-3) alone. Administration of TAK-085 [highly purified and concentrated n-3 fatty acid formulation containing EPA ethyl ester and docosahexaenoic acid (DHA, C22:6, n-3) ethyl ester] at 300 mg/kg body weight per day for 13 weeks reduced the number of reference memory-related errors in SHR-cp rats, but EPA alone had no effect, suggesting that long-term TAK-085 administration improves cognitive learning ability in a rat model of metabolic syndrome. However, the working memory-related errors were not affected in either of the rat groups. TAK-085 and EPA administration increased plasma EPA and DHA levels of SHR-cp rats, associating with an increase in EPA and DHA in the cerebral cortex. The TAK-085 administration decreased the lipid peroxide levels and reactive oxygen species in the cerebral cortex and hippocampus of SHR-cp rats, suggesting that TAK-085 increases antioxidative defenses. Its administration also increased the brain-derived neurotrophic factor levels in the cortical and hippocampal tissues of TAK-085-administered rats. The present study suggests that long-term TAK-085 administration is a possible therapeutic strategy for protecting against metabolic syndrome-induced learning decline.

Experimental evidence of ω-3 polyunsaturated fatty acid modulation of inflammatory cytokines and bioactive lipid mediators: their potential role in inflammatory, neurodegenerative, and neoplastic diseases

A large body of evidence has emerged over the past years to show the critical role played by inflammation in the pathogenesis of several diseases including some cardiovascular, neoplastic, and neurodegenerative diseases, previously not considered inflammation-related. The anti-inflammatory action of ω-3 polyunsaturated fatty acids (PUFAs), as well as their potential healthy effects against the development and progression of the same diseases, has been widely studied by our and others' laboratories. As a result, a rethinking is taking place on the possible mechanisms underlying the beneficial effects of ω-3 PUFAs against these disorders, and, in particular, on the influence that they may exert on the molecular pathways involved in inflammatory process, including the production of inflammatory cytokines and lipid mediators active in the resolving phase of inflammation. In the present review we will summarize and discuss the current knowledge regarding the modulating effects of ω-3 PUFAs on the production of inflammatory cytokines and proresolving or protective lipid mediators in the context of inflammatory, metabolic, neurodegenerative, and neoplastic diseases.

Omega-3 fatty acids and brain resistance to ageing and stress: body of evidence and possible mechanisms

The increasing life expectancy in the populations of rich countries raises the pressing question of how the elderly can maintain their cognitive function. Cognitive decline is characterised by the loss of short-term memory due to a progressive impairment of the underlying brain cell processes. Age-related brain damage has many causes, some of which may be influenced by diet. An optimal diet may therefore be a practical way of delaying the onset of age-related cognitive decline. Nutritional investigations indicate that the ω-3 poyunsaturated fatty acid (PUFA) content of western diets is too low to provide the brain with an optimal supply of docosahexaenoic acid (DHA), the main ω-3 PUFA in cell membranes. Insufficient brain DHA has been associated with memory impairment, emotional disturbances and altered brain processes in rodents. Human studies suggest that an adequate dietary intake of ω-3 PUFA can slow the age-related cognitive decline and may also protect against the risk of senile dementia. However, despite the many studies in this domain, the beneficial impact of ω-3 PUFA on brain function has only recently been linked to specific mechanisms. This review examines the hypothesis that an optimal brain DHA status, conferred by an adequate ω-3 PUFA intake, limits age-related brain damage by optimizing endogenous brain repair mechanisms. Our analysis of the abundant literature indicates that an adequate amount of DHA in the brain may limit the impact of stress, an important age-aggravating factor, and influences the neuronal and astroglial functions that govern and protect synaptic transmission. This transmission, particularly glutamatergic neurotransmission in the hippocampus, underlies memory formation. The brain DHA status also influences neurogenesis, nested in the hippocampus, which helps maintain cognitive function throughout life. Although there are still gaps in our knowledge of the way ω-3 PUFA act, the mechanistic studies reviewed here indicate that ω-3 PUFA may be a promising tool for preventing age-related brain deterioration.

Enhanced neuroprotective effect of fish oil in combination with quercetin against 3-nitropropionic acid induced oxidative stress in rat brain

While the beneficial effects of fish oil (FO) supplements on the central nervous system function are well established, few findings have led to the hypothesis that long term n-3 polyunsaturated fatty acid (n-3 PUFA) supplements at higher doses render the membranes more susceptible to lipid peroxidation. Hence recent studies suggest the use of dietary antioxidants as adjuncts with n-3 fatty acids to effectively improve the clinical outcome in neurological disorders. In the present investigation, we examined the hypothesis, if enrichment of FO with quercetin (a natural flavonoid) can provide a higher degree of neuroprotection and tested the same in a 3-nitropropionic acid (NPA) rat model. Growing male rats administered with NPA (25 mg/kg bw/d, i.p. 4 days) were provided either with FO (2 mL/kg bw), or Q (25mg/kg bw) or FO+Q for 14 days. NPA elicited marked oxidative stress in brain (striatum and cerebellum) as evidenced by significantly enhanced ROS, malondialdehyde, protein carbonyls and nitric oxide levels. Although varying degree of protection was evident among FO or Q groups, complete normalization of oxidative markers ensued only among FO+Q rats. Further, FO+Q combination completely normalized the elevated acetylcholinesterase activity and protected against NPA-induced mitochondrial dysfunctions. NPA induced depletion of dopamine levels was restored among all groups. Interestingly, NPA induced motor deficits were significantly improved among FO+Q rats. However, further studies are necessary to understand the mechanism/s by which FO enrichment with Q provides higher degree of protection. Nevertheless, our findings clearly suggest that the use of natural phytochemicals with moderate doses of FO may provide better neuroprotection and higher therapeutic advantage in the prevention or treatment of neurodegenerative diseases like Huntington's disease.