The protective effect of dietary eicosapentaenoic acid against impairment of spatial cognition learning ability in rats infused with amyloid beta(1-40)

The Neuropharmacological Evaluation of Seaweed: A Potential Therapeutic Source

The most common neurodegenerative diseases (NDDs), such as Alzheimer's disease (AD) and Parkinson's disease (PD), are the seventh leading cause of mortality and morbidity in developed countries. Clinical observations of NDD patients are characterized by a progressive loss of neurons in the brain along with memory decline. The common pathological hallmarks of NDDs include oxidative stress, the dysregulation of calcium, protein aggregation, a defective protein clearance system, mitochondrial dysfunction, neuroinflammation, neuronal apoptosis, and damage to cholinergic neurons. Therefore, managing this pathology requires screening drugs with different pathological targets, and suitable drugs for slowing the progression or prevention of NDDs remain to be discovered. Among the pharmacological strategies used to manage NDDs, natural drugs represent a promising therapeutic strategy. This review discusses the neuroprotective potential of seaweed and its bioactive compounds, and safety issues, which may provide several beneficial insights that warrant further investigation.

Lipid Peroxidation of the Docosahexaenoic Acid/Arachidonic Acid Ratio Relating to the Social Behaviors of Individuals with Autism Spectrum Disorder: The Relationship with Ferroptosis

Polyunsaturated fatty acids (PUFAs) undergo lipid peroxidation and conversion into malondialdehyde (MDA). MDA reacts with acetaldehyde to form malondialdehyde-modified low-density lipoprotein (MDA-LDL). We studied unsettled issues in the association between MDA-LDL and the pathophysiology of ASD in 18 individuals with autism spectrum disorders (ASD) and eight age-matched controls. Social behaviors were assessed using the social responsiveness scale (SRS). To overcome the problem of using small samples, adaptive Lasso was used to enhance the interpretability accuracy, and a coefficient of variation was used for variable selections. Plasma levels of the MDA-LDL levels (91.00 ± 16.70 vs. 74.50 ± 18.88) and the DHA/arachidonic acid (ARA) ratio (0.57 ± 0.16 vs. 0.37 ± 0.07) were significantly higher and the superoxide dismutase levels were significantly lower in the ASD group than those in the control group. Total SRS scores in the ASD group were significantly higher than those in the control group. The unbeneficial DHA/ARA ratio induced ferroptosis via lipid peroxidation. Multiple linear regression analysis and adaptive Lasso revealed an association of the DHA/ARA ratio with total SRS scores and increased MDA-LDL levels in plasma, resulting in neuronal deficiencies. This unbeneficial DHA/ARA-ratio-induced ferroptosis contributes to autistic social behaviors and is available for therapy.

Investigating Owner Use of Dietary Supplements in Dogs with Canine Cognitive Dysfunction

Canine cognitive dysfunction (CCD) is becoming increasingly recognized in veterinary medicine, as dogs live longer and with CCD being highly prevalent among the elderly dog population. Various studies have shown that diet and dietary supplementation can positively influence the clinical signs of CCD, especially if given at an early stage. The aim of this study was to investigate owner use of dietary supplements (DSs) in dogs with age-related behavioral changes. An observational study based on an online questionnaire for owners of dogs with age-related behavioral changes was performed. Out of a total of 394 owners who completed the survey, after noticing age-related behavioral changes, over half of the dogs received DSs (54%), whereas only 8% reported changing their dog's base diet. The most used DS was fish oil (48%). The use of DSs should be discussed with and monitored by veterinary surgeons since many geriatric patients have multi-morbidities, may have specific nutritional requirements and receive multi-faceted medications.

Neuroprotective Effect of Stearidonic Acid on Amyloid β-Induced Neurotoxicity in Rat Hippocampal Cells

Dietary intake of omega-3 fatty acids found in fish has been reported to reduce the risk of Alzheimer's Disease (AD). Stearidonic acid (SDA), a plant-based omega-3 fatty acid, has been targeted as a potential surrogate for fish-based fatty acids. However, its role in neuronal degeneration is unknown. This study was designed to evaluate effects of SDA on Amyloid-β(A-β)-induced neurotoxicity in rat hippocampal cells. Results showed that SDA effectively converted to eicosapentaenoic acid (EPA) in hippocampal cells. Aβ-induced apoptosis in H19-7 cells was protected by SDA pretreatment as evidenced by its regulation on the expression of relevant pro- and anti-apoptotic genes, as well as the inhibition on caspase activation. SDA also protected H19-7 cells from Aβ-induced oxidative stress by regulating the expression of relevant pro- and anti-oxidative genes, as well as the improvement in activity of catalase. As for Aβ/LPS-induced neuronal inflammation, SDA pretreatment reduced the release of IL-1β and TNFα. Further, we found that the anti-Aβ effect of SDA involves its inhibition on the expression of amyloid precursor protein and the regulation on MAPK signaling. These results demonstrated that SDAs have neuroprotective effect in Aβ-induced H19-7 hippocampal cells. This beneficial effect of SDA was attributed to its antiapoptotic, antioxidant, and anti-inflammatory properties.

Lipids and brain inflammation in APOE4-associated dementia

PURPOSE OF REVIEW

To highlight recent developments in studying mechanisms by which the apolipoprotein E4 (APOE4) allele affects the metabolism of brain lipids and predisposes the brain to inflammation and Alzheimer's disease (AD) dementia.

RECENT FINDINGS

APOE4 activates Ca2+ dependent phospholipase A2 (cPLA2) leading to changes in arachidonic acid (AA), eicosapentaenoic acid and docosahexaenoic acid signaling cascades in the brain. Among these changes, the increased conversion of AA to eicosanoids associates with sustained and unresolved chronic brain inflammation. The effects of APOE4 on the brain differ by age, disease stage, nutritional status and can be uncovered by brain imaging studies of brain fatty acid uptake. Reducing cPLA2 expression in the dementia brain presents a viable strategy that awaits to be tested.

SUMMARY

Fatty acid brain imaging techniques can clarify how changes to brain polyunsaturated fatty acid metabolism during the various phases of AD and guide the development of small molecules to mitigate brain inflammation.

Neuroprotection of Tropical Fruit Juice Mixture via the Reduction of iNOS Expression and CRH Level in β-Amyloid-Induced Rats Model of Alzheimer's Disease

This study aimed to determine the effects of tropical fruit juice mixture (pomegranate, white guava, and Roselle) on biochemical, behavioral, and histopathological changes of β-amyloid- (Aβ-) induced rats. Formulation 8 (F8) of tropical fruit juice mixture was chosen for this present study due to its high phenolic content and antioxidant capacity. Forty Wistar male rats were divided into five groups: dPBS (sham-operated control), dAβ (Aβ control), JPBS (F8 and PBS), JAβ (F8 and Aβ), and IBFAβ (ibuprofen and Aβ). F8 (5 ml/kg BW), and ibuprofen (10 ml/kg BW) was given orally daily for four weeks before the intracerebroventricular infusion of Aβ for two weeks. Histological analysis and neuronal count of hippocampus tissue in the Cornu Ammonis (CA1) region showed that supplementation with F8 was able to prevent Aβ-induced tissue damage and neuronal shrinkage. However, no significant difference in locomotor activity and novel object recognition (NOR) percentage was detected among different groups at day 7 and day 14 following Aβ infusion. Only effect of time differences (main effect of day) was observed at day 7 as compared to day 14, where reduction in locomotor activity and NOR percentage was observed in all groups, with F (1, 7) = 6.940, p < 0.05 and F (1, 7) = 7.152, p < 0.05, respectively. Besides, the MDA level of the JAβ group was significantly lower (p < 0.01) than that of the dPBS group. However, no significant changes in SOD activity were detected among different groups. Significant reduction in plasma CRH level (p < 0.05) and iNOS expression (p < 0.01) in the brain was detected in the JAβ group as compared to the dAβ group. Hence, our current findings suggest that the tropical fruit juice mixture (F8) has the potential to protect the rats from Aβ-induced neurotoxicity in brain hippocampus tissue possibly via its antioxidant properties and the suppression of iNOS expression and CRH production.

Eicosapentaenoic Acid-Enriched Phosphatidylcholine Mitigated Aβ1-42-Induced Neurotoxicity via Autophagy-Inflammasome Pathway

Recent studies indicated that neuroinflammation contributes to the exacerbation of Alzheimer's disease (AD) and plays an important role in AD. The NOD-like receptor protein 3 (NLRP3) inflammasome, which is an important component of innate immune system, is associated with a wide range of human central nervous system disorders, including AD. Most of the studies focus on the protective effects of docosahexaenoic acid (DHA) in AD, but eicosapentaenoic acid (EPA) has rarely been involved. Here, we investigate the effects of EPA in the forms of phosphatidylcholine (EPA-PC) and ethyl esters (EPA-EE) in improving Aβ1-42-induced neurotoxicity. The spatial memory ability and the biochemical changes in the hippocampus were measured, including glial cell activation, tumor necrosis factor α production, NLRP3 inflammasome activation, and autophagic flux. The present results showed that the AD rats were significantly protected from spatial memory loss by the supplementation (EPA + DHA = 60 mg/kg, i.g., 20 days) of EPA-PC, while EPA-EE showed no significant benefit. Further mechanism studies suggested that EPA-PC could inhibit Aβ-induced neurotoxicity by alleviating NLRP3 inflammasome activation and enhancing autophagy. These findings indicate that EPA could improve cognitive deficiency in Aβ1-42-induced AD rats via autophagic inflammasomal pathway and the bioactivity differs in its molecular form.

Effects of porcine brain hydrolysate on impairment of cognitive learning ability in amyloid β(1-40) -infused rats

This study assessed whether administering porcine brain hydrolysate (PBH) ameliorates the impairment of spatial cognition learning ability in amyloid β (Aβ)-infused rats. PBH was prepared using organic solvents (i.e., acetone and ethanol). Enzyme hydrolysates were derived from these PBH and the sequence of the Aβ peptide for infusion was selected. The results indicated the PBH, in particular EP (porcine brain extract with ethanol and protease N), demonstrated the potentials to reduce damage of neurodegenerative disorders in vitro and in vivo. The principal findings of this study indicate that PBH has prolyl endopeptidase inhibitory activity in vitro. Moreover, administering EP to Aβ(1-40)-infused rats significantly improves their performance on reference, spatial performance, and working memory tests during water maze tasks; concurrent proportional decreases are also observed in malondialdehyde levels, acetylcholinesterase (AChE) activity, and Aβ accumulation levels in brain tissues. The PBH was suggested to ameliorate learning deficits associated with Alzheimer's disease by inhibition of lipid peroxidation in the brain of Aβ infused rat.

A comparative study of eicosapentaenoic acid enriched phosphatidylcholine and ethyl ester in improving cognitive deficiency in Alzheimer's disease model rats

Molecular mechanisms of EPA-PC and EPA-EE in improving Aβ-induced cognitive deficiency in rats.

Geniposide attenuates Aβ25–35-induced neurotoxicity via the TLR4/NF-κB pathway in HT22 cells

Alzheimer's disease (AD), a neurodegenerative disorder, is marked by the accumulation of amyloid-β (Aβ) and neuroinflammation which promote the development of AD. Geniposide, the main ingredient isolated from Chinese herbal medicine Gardenia jasminoides Ellis, has a variety of pharmacological functions such as anti-apoptosis and anti-inflammatory activity. Hence, we estimated the inflammatory cytotoxicity caused by Aβ_25–35 and the neuroprotective effects of geniposide in HT22 cells. In this research, following incubation with Aβ_25–35 (40 μM, 24 h) in HT22 cells, the methylthiazolyl tetrazolium (MTT) and lactate dehydrogenase (LDH) release assays showed that the cell survival rate was significantly decreased. In contrast, the reactive oxygen species (ROS) assay indicated that Aβ_25–35 enhanced ROS accumulation and apoptosis showed in both hoechst 33342 staining and annexin V-FITC/PI double staining. And then, immunofluorescence test revealed that Aβ_25–35 promoted p65 to transfer into the nucleus indicating p65 was activated by Aβ_25–35. Moreover, western blot analysis proved that Aβ_25–35 increased the expression of nitric oxide species (iNOS), tumor necrosis factor-α (TNF-α), cyclooxygenase-2 (COX-2) and interleukin-1β (IL-1β). Simultaneously, Aβ_25–35 also promoted the expression of toll-like receptor 4 (TLR4), p-p65 and p-IκB-α accompanied with the increase in the level of beta-secretase 1 (BACE1) and caspase-3 which further supported Aβ_25–35 induced apoptosis and inflammation. Fortunately, this up-regulation was reversed by geniposide. In conclusion, our data suggest that geniposide can alleviate Aβ_25–35-induced inflammatory response to protect neurons, which is possibly involved with the inhibition of the TLR4/NF-κB pathway in HT22 cells. Geniposide may be the latent treatment for AD induced by neuroinflammation and apoptosis.

Alzheimer's disease (AD), a neurodegenerative disorder, is marked by the accumulation of amyloid-β (Aβ) and neuroinflammation which promote the development of AD.

Probiotics improve insulin resistance status in an experimental model of Alzheimer's disease

Background: Nowadays, Alzheimer's disease (AD) is considered as Type 3 diabetes in which insulin resistance is the common cause of both diseases. Disruption of insulin signaling cascade and insulin resistance can induce AD; and central insulin resistance causes systemic alterations in serum insulin, FBS levels, and lipid profile. Studies have shown that probiotics (Lactobacillus and Bifidobacterium species) can be used as a nutritional approach to improve these metabolic changes. We assessed the probiotic effect (4 species of Lactobacillus and Bifidobacterium) on insulin resistance biomarkers in an experimental model of AD. Methods: A total of 60 rats were divided into 5 groups: (1) a control group without surgical and dietary intervention; (2) a controlprobiotics group receiving probiotics for 8 weeks, but not receiving any surgical intervention; (3) a group receiving a sham operation in which PBS was injected intrahippocampus but without dietary intervention; (4) an Alzheimer group for which Amyloid-ß (Aß) 1- 42 was injected intrahippocampus but without dietary intervention; (5) and an Alzheimer-probiotics group for which Aß1-42 was injected intrahippocampus and given 2g probiotics for 8 weeks. The FBS levels and lipid profile were measured by a calorimetric method, insulin levels were detected by an ELISA kit, and HOMA-IR was calculated using a formula. ANOVA (one way analysis of variance followed by Bonferroni comparisons post hoc) was used to compare all the variables between groups. Results: Serum glucose, insulin levels, and HOMA-IR index increased in the Alzheimer group compared to the control (p<0.001), while probiotics decreased only insulin level and HOMA-IR index in AP group compared to Alzheimer group (p<0.001). Also, TG levels increased in the Alzheimer group (p<0.001), but no significant difference was detected between Alzheimer and Alzheimerprobiotics group. Conclusion: It seems that probiotics play an effective role in controlling glycemic status of Alzheimer's disease.

Omega-3 fatty acids revert high-fat diet-induced neuroinflammation but not recognition memory impairment in rats

Neuroinflammation is a consequence of overeating and may predispose to the development of cognitive decline and neurological disorders. This study aimed to evaluate the impact of omega-3 supplementation on memory and neuroinflammatory markers in rats fed a high-fat diet. Male Wistar rats were divided into four groups: standard diet (SD); standard diet + omega-3 (SD + O); high fat diet (HFD); and high fat diet + omega-3 (HFD + O). Diet administration was performed for 20 weeks and omega-3 supplementation started at the 16th week. HFD significantly increased body weight, while omega-3 supplementation did not modify the total weight gain. However, animals from the HFD + O group showed a lower level of visceral fat along with an improvement in insulin sensitivity following HFD. Thus, our results demonstrate a beneficial metabolic role of omega-3 following HFD. On the other hand, HFD animals presented an impairment in object recognition memory, which was not recovered by omega-3. In addition, there was an increase in GFAP-positive cells in the cerebral cortex of the HFD group, showing that omega-3 supplementation can be effective to decrease astrogliosis. However, no differences in GFAP number of cells were found in the hippocampus. We also demonstrated a significant increase in gene expression of pro-inflammatory cytokines IL-6 and TNF-α in cerebral cortex of the HFD group, reinforcing the anti-inflammatory role of this family of fatty acids. In summary, omega-3 supplementation was not sufficient to reverse the memory deficit caused by HFD, although it played an important role in reducing the neuroinflammatory profile. Therefore, omega-3 fatty acids may play an important role in the central nervous system, preventing the progression of neuroinflammation in obesity.

Neuroprotective effects of low fat-protein diet in the P301L mouse model of tauopathy

Tauopathies are a class of neurodegenerative diseases associated with the pathological aggregation of tau protein in the human brain. Although numerous studies in mouse models of Alzheimer disease (AD) have shown a correlation among diet, beta-amyloid and AD onset, little is known about the impact of diet on Tau. We investigated whether a low fat-protein diet (LFPD) may improve lifespan, cognitive and locomotor activity in P301L-tg mouse model of tauopathy. Our data indicate that LFPD has a beneficial effect on these parameters. Tg mice fed with standard diet shown a decrease in body weight, food intake and survival rate if compared to wild type animals. In contrast, LFPD counteracted weight loss, increased mortality and ameliorated cognitive and locomotor performances in tg mice. LFPD also reduced the abnormal accumulation of agglomerates of P-Tau (pathological features of tauopathies) and the expression of apoptotic markers (i.e., TUNEL immunopositive neurons) in the prefrontal cerebral cortex and hippocampus of P301L-tg mice. Interestingly, some of these effects are sex-dependent. For instance, tg females, but not males, fed with LFPD had a significant increase of body weight and a reduction of P-Tau agglomerates compared to tg fed with standard diet. These changes correlated with a more pronounced improvement of cognition and locomotor activity in females than in male tg fed with LFPD. Altogether, these results suggest a sex dependent neuroprotective effect of LFPD in P301L-tg mice, suggesting that lifestyle intervention strategies may be clinically relevant for delaying the onset of cognitive impairment and dementia, especially in females.

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.

Proximate composition and fatty acid analysis of Lablab purpureus (L.) legume seed: implicates to both protein and essential fatty acid supplementation

The high mortality rate in Bangladesh is related to poverty, which results in protein malnutrition, essential fatty acid deficiency and lacks in adequate vitamins, minerals and calorie. Exploring new food items with improved dietary nutrition factors may, therefore, help to decrease the mortality rate in the poor countries like Bangladesh. Accordingly, the present study was a proximate composition and fatty acid analysis of L. purpureus seed—a legume seed which is given no careful attention locally, though it might be a good source of valuable nutrition factors for both animals and humans. The purpose of the study was, therefore, to generate awareness that L. purpureus could also act as a good source of food components essential for good health. Proximate analysis revealed that the seed powder contained 8.47 ± 0.52% moisture; 3.50 ± 0.0.07% ash; 1.02 ± 0.06% total fat; 23.95 ± 0.15% total protein; 1.21 ± 0.16% total dietary fiber; 61.86 ± 0.70% total carbohydrate and 352.4 ± 2.66 kcal/100 g energy. Phytic acid content (%) was 1.014 ± 0.048. Major fatty acid composition (%): the essential fatty acid linoleic acid (C18:2, ω-6) was 9.50 ± 0.68, while the linolenic acid (C18:3, ω-3) was 1.95 ± 0.18. Palmitic acid (C16:0), stearic acid (C18:0) and oleic acid (C18:1) were, respectively, 2.96 ± 0.19, 0.77 ± 0.04 and 1.10 ± 0.06. Lignoceric acid (C24:0) was 0.11 ± 0.007%. Monounsaturated palmitoleic acid (0.006 ± 0.0), docosapentaenoic acid (DPA, C22:5, ω-3) and nervonic acid (0.002 ± 0.0) were present in trace amounts. Arachidonic acid (AA, C20:4, ω-6), eicosapentaenoic acid (C20:5, ω-3), and docosahexaenoic acid (C22:6, ω-3) were not detected. The fatty acid profile, thus, suggests that essential omega-6 fatty acid linoleic acid (C18:3, ω-6) and omega-3 linolenic acid (C18:3, ω-3) were the major polyunsaturated fatty acids (PUFA) present in L. purpureus seed. In addition, the seed contained high amount of proteins. Finally, these results suggest that L. purpureus seed could be used as a good source of quality food components, including protein and essential fatty acids.

Omega-3 Polyunsaturated Fatty Acids and Oxylipins in Neuroinflammation and Management of Alzheimer Disease

Alzheimer disease (AD) is becoming one of the most prevalent neurodegenerative conditions worldwide. Although the disease progression is becoming better understood, current medical interventions can only ameliorate some of the symptoms but cannot slow disease progression. Neuroinflammation plays an important role in the advancement of this disorder, and n-3 (ω-3) polyunsaturated fatty acids (PUFAs) are involved in both the reduction in and resolution of inflammation. These effects may be mediated by the anti-inflammatory and proresolving effects of bioactive lipid mediators (oxylipins) derived from n-3 PUFAs [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] in fish oil. Although interventions have generally used fish oil containing both EPA and DHA, several studies that used either EPA or DHA alone or specific oxylipins derived from these fatty acids indicate that they have distinct effects. Both DHA and EPA can reduce neuroinflammation and cognitive decline, but EPA positively influences mood disorders, whereas DHA maintains normal brain structure. Fewer studies with a plant-derived n-3 PUFA, α-linolenic acid, suggest that other n-3 PUFAs and their oxylipins also may positively affect AD. Further research identifying the unique anti-inflammatory and proresolving properties of oxylipins from individual n-3 PUFAs will enable the discovery of novel disease-management strategies in AD.

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.

Omega-3 Fatty Acids: Possible Neuroprotective Mechanisms in the Model of Global Ischemia in Rats

Background. Omega-3 (ω3) administration was shown to protect against hypoxic-ischemic injury. The objectives were to study the neuroprotective effects of ω3, in a model of global ischemia. Methods. Male Wistar rats were subjected to carotid occlusion (30 min), followed by reperfusion. The groups were SO, untreated ischemic and ischemic treated rats with ω3 (5 and 10 mg/kg, 7 days). The SO and untreated ischemic animals were orally treated with 1% cremophor and, 1 h after the last administration, they were behaviorally tested and euthanized for neurochemical (DA, DOPAC, and NE determinations), histological (Fluoro jade staining), and immunohistochemical (TNF-alpha, COX-2 and iNOS) evaluations. The data were analyzed by ANOVA and Newman-Keuls as the post hoc test. Results. Ischemia increased the locomotor activity and rearing behavior that were partly reversed by ω3. Ischemia decreased striatal DA and DOPAC contents and increased NE contents, effects reversed by ω3. This drug protected hippocampal neuron degeneration, as observed by Fluoro-Jade staining, and the increased immunostainings for TNF-alpha, COX-2, and iNOS were partly or totally blocked by ω3. Conclusion. This study showed a neuroprotective effect of ω3, in great part due to its anti-inflammatory properties, stimulating translational studies focusing on its use in clinic for stroke managing.

Dietary DHA supplementation causes selective changes in phospholipids from different brain regions in both wild type mice and the Tg2576 mouse model of Alzheimer's disease

Alzheimer's disease (AD) is of major concern in ageing populations and we have used the Tg2576 mouse model to understand connections between brain lipids and amyloid pathology. Because dietary docosahexaenoic acid (DHA) has been identified as beneficial, we compared mice fed with a DHA-supplemented diet to those on a nutritionally-sufficient diet. Major phospholipids from cortex, hippocampus and cerebellum were separated and analysed. Each phosphoglyceride had a characteristic fatty acid composition which was similar in cortex and hippocampus but different in the cerebellum. The biggest changes on DHA-supplementation were within ethanolamine phospholipids which, together with phosphatidylserine, had the highest proportions of DHA. Reciprocal alterations in DHA and arachidonate were found. The main diet-induced alterations were found in ethanolamine phospholipids, (and included their ether derivatives), as were the changes observed due to genotype. Tg mice appeared more sensitive to diet with generally lower DHA percentages when on the standard diet and higher relative proportions of DHA when the diet was supplemented. All four major phosphoglycerides analysed showed age-dependent decreases in polyunsaturated fatty acid contents. These data provide, for the first time, a detailed evaluation of phospholipids in different brain areas previously shown to be relevant to behaviour in the Tg2576 mouse model for AD. The lipid changes observed with genotype are consistent with the subtle alterations found in AD patients, especially for the ethanolamine phospholipid molecular species. They also emphasise the contrasting changes in fatty acid content induced by DHA supplementation within individual phospholipid classes.

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.

Long-term omega-3 supplementation modulates behavior, hippocampal fatty acid concentration, neuronal progenitor proliferation and central TNF-α expression in 7 month old unchallenged mice

Dietary polyunsaturated fatty acid (PUFA) manipulation is being investigated as a potential therapeutic supplement to reduce the risk of developing age-related cognitive decline (ARCD). Animal studies suggest that high omega (Ω)-3 and low Ω-6 dietary content reduces cognitive decline by decreasing central nervous system (CNS) inflammation and modifying neuroimmune activity. However, no previous studies have investigated the long term effects of Ω-3 and Ω-6 dietary levels in healthy aging mice leaving the important question about the preventive effects of Ω-3 and Ω-6 on behavior and underlying molecular pathways unaddressed. We aimed to investigate the efficacy of long-term Ω-3 and Ω-6 PUFA dietary supplementation in mature adult C57BL/6 mice. We measured the effect of low, medium, and high Ω-3:Ω-6 dietary ratio, given from the age of 3–7 months, on anxiety and cognition-like behavior, hippocampal tissue expression of TNF-α, markers of neuronal progenitor proliferation and gliogenesis and serum cytokine concentration. Our results show that a higher Ω-3:Ω-6 PUFA diet ratio increased hippocampal PUFA, increased anxiety, improved hippocampal dependent spatial memory and reduced hippocampal TNF-α levels compared to a low Ω-3:Ω-6 diet. Furthermore, serum TNF-α concentration was reduced in the higher Ω-3:Ω-6 PUFA ratio supplementation group while expression of the neuronal progenitor proliferation markers KI67 and doublecortin (DCX) was increased in the dentate gyrus as opposed to the low Ω-3:Ω-6 group. Conversely, Ω-3:Ω-6 dietary PUFA ratio had no significant effect on astrocyte or microglia number or cell death in the dentate gyrus. These results suggest that supplementation of PUFAs may delay aging effects on cognitive function in unchallenged mature adult C57BL/6 mice. This effect is possibly induced by increasing neuronal progenitor proliferation and reducing TNF-α.

Genistein antagonizes inflammatory damage induced by β-amyloid peptide in microglia through TLR4 and NF-κB

OBJECTIVES

Microglia activation and neuroinflammation have been associated with the pathogenesis of neurodegenerative disorders such as Alzheimer's disease (AD). Toll-like receptor 4 (TLR4) and nuclear factor (NF)-κB-mediated signal pathways exert key modulating roles in the inflammatory processes. The aim of the present study was to investigate whether genistein (Gen) has a neuroprotective effect against inflammatory damage induced by β-amyloid peptide25-35 (Aβ25-35) through the TLR4 and NF-κB-mediated signal pathways.

METHODS

BV-2 microglia cells were preincubated with Gen for 2 h and then treated with 25 μM Aβ25-35 for another 24 h. The expression of inflammatory mediators, TLR4 and NF-κB and the activity of NF-κB were measured.

RESULTS

The results showed that Gen could attenuate the cytotoxicity and inflammatory damage induced by Aβ25-35. Gen also significantly reversed Aβ25-35-induced up-regulation of TLR4 and NF-κB expression and the DNA binding and transcriptional activities of NF-κB.

CONCLUSION

These results indicated that Gen could alleviate the inflammation caused by Aβ25-35 treatment, which might be associated with the regulation of the TLR4/NF-κB signal pathway.

Effects of Krill-derived phospholipid-enriched n-3 fatty acids on Ca(2+) regulation system in cerebral arteries from ovariectomized rats

AIMS

To investigate the effects of n-3 polyunsaturated fatty acids on cerebral circulation, ovariectomized (OVX) rats were administered with phospholipids in krill oil (KPL) or triglycerides in fish oil (FTG); effects on the Ca(2+) regulating system in their basilar artery (BA) were then analyzed.

MAIN METHODS

The rats were divided into 4 groups: control, OVX, OVX given KPL (OVXP), and OVX given FTG (OVXT) orally, daily for 2weeks. Time dependent relaxation (TDR) of contractile response to 5HT in BA was determined myographically, Na(+)/Ca(2+) exchanger (NCX) 1 mRNA expression was determined by real time PCR, and nucleotides were analyzed by HPLC.

KEY FINDINGS

The level of TDR in OVX that was significantly lower in the control was inhibited by l-NAME and indomethacin; TEA inhibited TDR totally in the control but only partly in OVXP and OVXT. Relaxation induced by the addition of 5mM KCl to the BA pre-contracted with 5-HT was inhibited by TEA in the controls, OVXP and OVXT, but not in OVX. Overexpression of NCX1 mRNA in the BA from OVX was significantly inhibited by FTG. The ratio of ADP/ATP in cerebral arteries from OVX was significantly inhibited by KPL and FTG. Levels of triglyceride and arachidonic acid in the plasma of OVX increased, but were significantly inhibited by KPL and FTG.

SIGNIFICANCE

Ovarian dysfunction affects Ca(2+) activated-, ATP-sensitive-K(+) channels and NCX1, which play crucial roles in the autoregulation of cerebral blood flow. Also, KPL may become as good a supplement as FTG for postmenopausal women.

Soybean isoflavone ameliorates β-amyloid 1-42-induced learning and memory deficit in rats by protecting synaptic structure and function

This research aims to investigate whether soybean isoflavone (SIF) could alleviate the learning and memory deficit induced by β-amyloid peptides 1-42 (Aβ 1-42) by protecting the synapses of rats. Adult male Wistar rats were randomly allocated to the following groups: (1) control group; (2) Aβ 1-42 group; (3) SIF group; (4) SIF + Aβ 1-42 group (SIF pretreatment group) according to body weight. The 80 mg/kg/day of SIF was administered orally by gavage to the rats in SIF and SIF+Aβ 1-42 groups. Aβ 1-42 was injected into the lateral cerebral ventricle of rats in Aβ 1-42 and SIF+Aβ 1-42 groups. The ability of learning and memory, ultramicrostructure of hippocampal synapses, and expression of synaptic related proteins were investigated. The Morris water maze results showed the escape latency and total distance were decreased in the rats of SIF pretreatment group compared to the rats in Aβ1-42 group. Furthermore, SIF pretreatment could alleviate the synaptic structural damage and antagonize the down-regulation expressions of below proteins induced by Aβ1-42: (1) mRNA and protein of the synaptophysin and postsynaptic density protein 95 (PSD-95); (2) protein of calmodulin (CaM), Ca(2+) /calmodulin-dependent protein kinase II (CaMK II), and cAMP response element binding protein (CREB); (3) phosphorylation levels of CaMK II and CREB (pCAMK II, pCREB). These results suggested that SIF pretreatment could ameliorate the impairment of learning and memory ability in rats induced by Aβ 1-42, and its mechanism might be associated with the protection of synaptic plasticity by improving the synaptic structure and regulating the synaptic related proteins.

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.

Dietary supplementation with resveratrol and/or docosahexaenoic acid alters hippocampal gene expression in adult C57Bl/6 mice

The hippocampus is an important brain structure for multiple cognitive functions, including memory formation. It is particularly sensitive to insults, such as stress, ischemia, and aging; all of these can affect hippocampal and therefore cognitive function. To understand the potential of diet for the preservation of hippocampal function, we investigated the effects of dietary supplementation with resveratrol (RES) or docosahexaenoic acid (DHA), or their combination, on hippocampal gene expression in adult C57BL/6 mice. Animals in the supplemented group received either 50 mg/kg/day of RES or DHA, while the combination group received 50 mg/kg/day of each supplement. Dietary supplements were mixed with the AIN93G diet, and supplementation lasted 6 weeks. The control group received AIN93G diet alone for the same period. At the end of the experiment, the hippocampi were processed for genome-wide gene expression and pathway analyses. Most of the genes that were significantly altered were associated with inflammatory responses as determined by pathway analysis. RES-supplemented animals showed decreased expression of IL-6 (P=.001), MAPKapk2 (P=.015), and increased expression for PI3KR2 (P=.034) and Wnt7a (P=.004) expression. DHA-supplemented animals showed a decreased IL-6 (P=.003) and an increased Wnt7a (P=.003) expression. Animals on the combination diet showed a decreased IL-6 (P=.005) and Apolipoprotien E (ApoE) (P=.035) expression. Our findings demonstrate that hippocampal gene expression is significantly altered by all three dietary supplementation regimes. Moreover, our analysis indicates that RES and DHA likely exert their beneficial effects through antiinflammatory mechanisms.

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 polyunsaturated Fatty acids enhance neuronal differentiation in cultured rat neural stem cells

Polyunsaturated fatty acids (PUFAs) can induce neurogenesis and recovery from brain diseases. However, the exact mechanisms of the beneficial effects of PUFAs have not been conclusively described. We recently reported that docosahexaenoic acid (DHA) induced neuronal differentiation by decreasing Hes1 expression and increasing p27^kip1 expression, which causes cell cycle arrest in neural stem cells (NSCs). In the present study, we examined the effect of eicosapentaenoic acid (EPA) and arachidonic acid (AA) on differentiation, expression of basic helix-loop-helix transcription factors (Hes1, Hes6, and NeuroD), and the cell cycle of cultured NSCs. EPA also increased mRNA levels of Hes1, an inhibitor of neuronal differentiation, Hes6, an inhibitor of Hes1, NeuroD, and Map2 mRNA and Tuj-1-positive cells (a neuronal marker), indicating that EPA induced neuronal differentiation. EPA increased the mRNA levels of p21^cip1 and p27^kip1, a cyclin-dependent kinase inhibitor, which indicated that EPA induced cell cycle arrest. Treatment with AA decreased Hes1 mRNA but did not affect NeuroD and Map2 mRNA levels. Furthermore, AA did not affect the number of Tuj-1-positive cells or cell cycle progression. These results indicated that EPA could be involved in neuronal differentiation by mechanisms alternative to those of DHA, whereas AA did not affect neuronal differentiation in NSCs.

Soy isoflavone attenuates brain mitochondrial oxidative stress induced by β-amyloid peptides 1-42 injection in lateral cerebral ventricle

The aim of this study is to investigate whether soy isoflavone (SIF) reduces oxidative stress and improves the antioxidant ability in mitochondria of rat brain damaged by injection of beta-amyloid peptides 1-42 (Aβ1-42). Forty Wistar rats were randomly divided into control, Aβ1-42, SIF + Aβ1-42, and SIF groups according to body weight. The rats in the SIF + Aβ1-42 group and SIF group were intragastrically administered SIF suspension in 0.5% CMC-Na for 28 days, whereas the rats in control group and Aβ1-42 group were administered the same volume of 0.5% CMC-Na. On day 14, the rats in the Aβ1-42 group and SIF + Aβ1-42 group were injected with Aβ1-42 into the lateral cerebral ventricle with physiological saline. The rat brains were then sampled, and brain mitochondria were isolated. After this, the mitochondrial membrane potential (MMP) and mitochondrial redox state were measured. The contents of brain nuclear factor E2-related factor (Nrf2) and heme oxygenase-1 (HO-1) protein in brain tissue were quantitated by Western blot. The results showed that SIF maintained the MMP, elevated the reduced glutathione/oxidized glutathione (GSH/GSSG) ratio, and increased glutathione peroxidase (GPx) and manganese superoxide dismutase (MnSOD) protein expression in brain mitochondria. Additionally, SIF reversed the Aβ1-42-induced downregulation of the protein expression of Nrf2 and HO-1 in brain tissue. These results indicated that SIF could alleviate the oxidative damage and maintain the redox imbalance in brain mitochondria damaged by Aβ1-42. This might result from regulation of the Nrf2/HO-1 pathway.

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'.

Pattern recognition receptors involved in the inflammatory attenuating effects of soybean isoflavone in β-amyloid peptides 1-42 treated rats

Pattern recognition receptors (PRRs) play important roles in the inflammatory responses to Alzheimer's disease (AD). Our previous study indicated that soybean isoflavone (SIF) exhibited anti-inflammatory effect in rats treated by β-amyloid peptides1-42 (Aβ1-42). In present study, we further detected the effects of SIF against inflammation caused by Aβ1-42 treatment in rats. Serum inflammatory mediators and neurotrophic factors including transforming growth factor-β (TGF-β), inducible nitric oxide synthase (iNOS), brain-derived neurotrophic factor (BDNF) and S100β were detected by enzyme-like immunosorbent assay (ELISA). Reverse transcription-polymerase chain reaction (RT-PCR) and western blot methods were applied for detecting mRNA and protein expression of interleukin-1β (IL-1β), iNOS, tumor necrosis factor-α (TNF-α), TGF-β, BDNF, S100β, myeloid differentiation factor88 (Myd88), Toll-like receptor2 (TLR2), formyl peptide receptors (FPRs), inhibitor κB kinase (IKK) and inhibitor κB-α (IκB-α) in rat's brain tissue. Our results indicated that SIF could reduce the production of IL-1β, TNF-α and iNOS induced by Aβ1-42 in serum and brain of rats. SIF also significantly reversed Aβ1-42-induced up-regulation of TLR2, FPR, Myd88, IKK and decreased IκB-α mRNA and protein expressions in rats. These results suggested that TLR2 and FPR might involve in the inflammatory process induced by Aβ1-42 treatment, and SIF was an efficiency compound in reversing the inflammation caused by Aβ1-42 treatment.

Cis-9,trans-11-conjugated linoleic acid promotes neuronal differentiation through regulation of Hes6 mRNA and cell cycle in cultured neural stem cells

Conjugated linoleic acids (CLAs) are positional and geometrical isomers of linoleic acid (LA). Cis-9,trans-11-CLA (CLA), the main isomer of CLAs in foods derived from ruminants, has several beneficial effects for humans and animals; however, its effects on the central nervous system are largely unknown. In this study, we investigated the effects of LA and CLA on neuronal differentiation of neural stem cells (NSCs). NSCs cultured with or without LA and CLA were assessed by immunofluorescence staining, mRNA measurement of basic helix-loop-helix transcription factors and cyclin-dependent kinase inhibitors by real-time PCR, BrdU incorporation analysis and flow cytometry analysis. In NSCs treated with CLA, the number of Tuj-1-positive cells (neurons) and the mRNA expression levels of Hes6, MAP2, p21(cip1) and p27(kip1) increased, while the proportion of S-phase cells decreased; compared with the control, no change was demonstrated in NSCs treated with LA. These results suggest that CLA promotes neuronal differentiation by increasing, in part, the expression of Hes6 mRNA and by activating p21(cip1) and p27(kip1) to arrest cell cycle.

Soybean isoflavone alleviates β-amyloid 1-42 induced inflammatory response to improve learning and memory ability by down regulation of Toll-like receptor 4 expression and nuclear factor-κB activity in rats

β-amyloid 1-42 (Aβ1-42)-induced learning and memory impairment in rats is believed to be associated with inflammation. Cytokine production is a key pathologic event in the progression of inflammatory processes. In this rat study, soybean isoflavones (SIF) was used to investigate it's protective effects on inflammation caused by β-amyloid 1-42 (Aβ1-42), which is associated with learning and memory impairment in Alzheimer disease. We characterized the learning and memory ability. cytokine profiles of circulating interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α) in the serum and the expression of Toll like receptor4 (TLR4) and nuclear factor-κB p65 (NF-κB p65) mRNA and protein in the brain tissue following intracerebroventricular administration of Aβ1-42 by miniosmotic pump for 14 days. The results showed that functional deficits of learning and memory in SIF treatment groups were significantly improved compared to the control group without SIF treatment in water maze test. The serum IL-1β and TNF-α level were significantly increased, and the expressions of TLR4 and NF-κB p65 mRNA and protein in the brain were up-regulated, indicating inflammation response was initiated following administration of Aβ1-42. After intragastric pre-treatment with SIF, inflammatory cytokines was significantly reduced and also SIF reversed the Aβ1-42 induced up-regulation of TLR4 and NF-κB p65 mRNA and protein expression in the brain and expression of NF-κB p65 in nuclei. These results suggested that SIF reduced the cytokine cascade and inflammatory response induced by Aβ1-42 which could result in the improvement of spatial learning and memory ability impairment in the rats.

The polyunsaturated fatty acids, EPA and DPA exert a protective effect in the hippocampus of the aged rat

Age is characterized by deficits in synaptic function identified by decreased performance of aged animals in spatial learning tasks and reduced ability of animals to sustain long term potentiation (LTP). Several cellular and molecular events are correlated with these deficits, many of which are indicative of age-related neuroinflammatory and oxidative cell stress. It is significant that agents which decrease microglial activation are commonly associated with restoration of function. We set out to examine whether the n-3 polyunsaturated fatty acid docosapentaenoic acid (DPA), which is a metabolite of eicosapentaenoic acid (EPA), could modulate the age-related increase in microglial activation and the associated increase in oxidative changes and therefore impact on synaptic function in aged rats. We demonstrate that docosapentaenoic acid possesses neurorestorative effects and is capable of downregulating microglial activation. The data show that it also decreases the coupled activation of sphingomyelinase and caspase 3, probably because of its ability to decrease age-related oxidative changes, and consequently attenuates the age-related decrease in spatial learning and long-term potentiation.

Mechanisms of n-3 fatty acid-mediated development and maintenance of learning memory performance

Docosahexaenoic acid (DHA, 22:6n-3) is specifically enriched in the brain and mainly anchored in the neuronal membrane, where it is involved in the maintenance of normal neurological function. Most DHA accumulation in the brain takes place during brain development in the perinatal period. However, hippocampal DHA levels decrease with age and in the brain disorder Alzheimer's disease (AD), and this decrease is associated with reduced hippocampal-dependent spatial learning memory ability. A potential mechanism is proposed by which the n-3 fatty acids DHA and eicosapentaenoic acid (20:5n-3) aid the development and maintenance of spatial learning memory performance. The developing brain or hippocampal neurons can synthesize and take up DHA and incorporate it into membrane phospholipids, especially phosphatidylethanolamine, resulting in enhanced neurite outgrowth, synaptogenesis and neurogenesis. Exposure to n-3 fatty acids enhances synaptic plasticity by increasing long-term potentiation and synaptic protein expression to increase the dendritic spine density, number of c-Fos-positive neurons and neurogenesis in the hippocampus for learning memory processing. In aged rats, n-3 fatty acid supplementation reverses age-related changes and maintains learning memory performance. n-3 fatty acids have anti-oxidative stress, anti-inflammation, and anti-apoptosis effects, leading to neuron protection in the aged, damaged, and AD brain. Retinoid signaling may be involved in the effects of DHA on learning memory performance. Estrogen has similar effects to n-3 fatty acids on hippocampal function. It would be interesting to know if there is any interaction between DHA and estrogen so as to provide a better strategy for the development and maintenance of learning memory.

Are omega-3 fatty acids options for prevention and treatment of cognitive decline and dementia?

PURPOSE OF REVIEW

To report recent data on the potential role of omega-3 fatty acids (n-3 FA) found in oily fish, especially docosahexaenoic acid (DHA), to prevent and treat cognitive decline and Alzheimer's disease.

RECENT FINDINGS

Observational studies still provide conflicting results, in which the majority indicate beneficial effects on cognition, both when assessed as a continuous variable or as incident dementia, mainly Alzheimer's disease. Experimental studies have demonstrated potentially ameliorating effects of eicosapentaenoic acid (EPA) and DHA on amyloid fragment formation, signal transduction including upregulation of the apolipoprotein receptor SorLA, as well as on angiogenesis. The role of EPA and DHA metabolites on Alzheimer's disease pathology is under investigation. Recently, three randomized intervention studies, with duration up to 6 months have been reported. In contrast to a small study from Taiwan, no positive overall effects were reported from the Swedish OmegAD Study or from a Dutch study, although post hoc analyses indicate that selected individuals with mild forms of Alzheimer's disease or cognitive decline may respond to treatment.

SUMMARY

No firm conclusions can be drawn. Based on epidemiological data, fish including oily fish could be advised as part of a balanced diet for public health purpose, although the evidence for better cognition is only fairly consistent. It is unlikely that n-3 FA will emerge as a treatment option in general for improving cognitive function in patients with Alzheimer's disease. n-3 FA, especially DHA, may turn out as an adjuvant therapy in selected cases. Further long-term intervention studies on individuals with mild cognitive reductions are awaited.

Small molecule beta-amyloid inhibitors that stabilize protofibrillar structures in vitro improve cognition and pathology in a mouse model of Alzheimer's disease

Beta-amyloid (Abeta) peptides are thought to play a major role in the pathogenesis of Alzheimer's disease. Compounds that disrupt the kinetic pathways of Abeta aggregation may be useful in elucidating the role of oligomeric, protofibrillar and fibrillar Abeta in the etiology of the disease. We have previously reported that scyllo-inositol inhibits Abeta(42) fibril formation but the mechanism(s) by which this occurs has not been investigated in detail. Using a series of scyllo-inositol derivatives in which one or two hydroxyl groups were replaced with hydrogen, chlorine or methoxy substituents, we examined the role of hydrogen bonding and hydrophobicity in the structure-function relationship of scyllo-inositol-Abeta binding. We report here that all scyllo-inositol derivatives demonstrated reduced effectiveness in preventing Abeta(42) fibrillization compared with scyllo-inositol, suggesting that scyllo-inositol interacts with Abeta(42) via key hydrogen bonds that are formed by all hydroxyl groups. Increasing the hydrophobicity of scyllo-inositol by the addition of two methoxy groups (1,4-di-O-methyl-scyllo-inositol) produced a derivative that stabilized Abeta(42) protofibrils in vitro. Prophylactic administration of 1,4-di-O-methyl-scyllo-inositol to TgCRND8 mice attenuated spatial memory impairments and significantly decreased cerebral amyloid pathology. These results suggest that Abeta aggregation can be targeted at multiple points along the kinetic pathway for the improvement of Alzheimer's disease-like pathology.

Reductions of acetylcholine release and nerve growth factor expression are correlated with memory impairment induced by interleukin-1beta administrations: effects of omega-3 fatty acid EPA treatment

Interleukin (IL)-1beta may play an important role in Alzheimer's disease. However, the relationships between glucocorticoids and acetylcholine (ACh), and between neurotrophins and ACh in IL-1-induced memory deficits are unknown. While ethyl-eicosapentaenoate (E-EPA) has recently been reported to reduce inflammation and improve memory, cholinergic and neurotrophic mechanisms by which E-EPA improves memory is unclear. This study evaluated: (i) the correlation between ACh release and memory impairment; (ii) the effect of glucocorticoids on ACh release; (iii) the relationship between nerve growth factor (NGF) and inflammation; and (iv) the effects of E-EPA treatment on IL-1beta-induced changes. Intracerebroventricular IL-1beta administrations produced a significant reduction in hippocampal ACh release in rats fed control diet, which was partially attenuated by mifepristone (RU 486) and completely blocked by IL-1 receptor antagonist. In eight-arm radial maze, significantly less ACh release was correlated with the memory deficits after IL-1beta administrations. mRNA expression of hippocampal NGF was lower, whereas IL-1beta was higher when compared with controls. E-EPA treatment significantly improved the memory, which was correlated with normalizing ACh release, and expressions of NGF and IL-1beta. This study revealed important mechanisms by which IL-1beta impairs, while E-EPA improves memory through IL-1-glucocorticoid-ACh release and IL-1-NGF-ACh release pathways.