Behavioral, neuromorphological, and neurobiochemical effects induced by omega-3 fatty acids following basal forebrain cholinergic depletion in aged mice

The role of olive oil and its constituents in mental health: a scoping review

Mounting evidence suggests that the Mediterranean diet has a beneficial effect on mental health. It has been hypothesised that this effect is mediated by a variety of foods, nutrients and constituents; however, there is a need for research elucidating which of these components contribute to the therapeutic effect. This scoping review sought to systematically search for and synthesise the research on olive oil and its constituents and their impact on mental health, including the presence or absence of a mental illness or the severity or progression of symptoms. PubMed and OVID MEDLINE databases were searched. The following article types were eligible for inclusion: human experimental and observational studies, animal and preclinical studies. Abstracts were screened in duplicate, and data were extracted using a piloted template. Data were analysed qualitatively to assess trends and gaps for further study. The PubMed and OVID MEDLINE search yielded 544 and 152 results, respectively. After full-text screening, forty-nine studies were eligible for inclusion, including seventeen human experimental, eighteen observational and fourteen animal studies. Of these, thirteen human and four animal studies used olive oil as a comparator. Observational studies reported inconsistent results, specifically five reporting higher rates of mental illness, eight reporting lower and five reporting no association with higher olive oil intake. All human experimental studies and nine of ten animal studies that assess olive oil as an intervention reported an improvement of anxiety or depression symptoms. Olive oil may benefit mental health outcomes. However, more experimental research is needed.

Omega-3 Polyunsaturated Fatty Acids in Depression

Omega-3 polyunsaturated fatty acids have received considerable attention in the field of mental health, in particular regarding the treatment of depression. This review presents an overview of current research on the role of omega-3 fatty acids in the prevention and treatment of depressive disorders. The existing body of evidence demonstrates that omega-3 fatty acids, in particular eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), have antidepressant effects that can be attributed to their modulation of neuroinflammation, neurotransmitter function, and neuroplasticity. Nevertheless, clinical trials of omega-3 supplementation have yielded inconsistent results. Some studies have demonstrated significant reductions in depressive symptoms following omega-3 treatment, whereas others have shown minimal to no beneficial impact. A range of factors, encompassing dosage, the ratio of EPA to DHA, and baseline nutritional status, have been identified as having a potential impact on the noted results. Furthermore, it has been suggested that omega-3 fatty acids may act as an adjunctive treatment for those undergoing antidepressant treatment. Notwithstanding these encouraging findings, discrepancies in study designs and variability in individual responses underscore the necessity of further research in order to establish uniform, standardized guidelines for the use of omega-3 fatty acids in the management of depressive disorders.

Essential role of p21Waf1/Cip1 in the modulation of post-traumatic hippocampal Neural Stem Cells response

BACKGROUND

Traumatic Brain Injury (TBI) represents one of the main causes of brain damage in young people and the elderly population with a very high rate of psycho-physical disability and death. TBI is characterized by extensive cell death, tissue damage and neuro-inflammation with a symptomatology that varies depending on the severity of the trauma from memory loss to a state of irreversible coma and death. Recently, preclinical studies on mouse models have demonstrated that the post-traumatic adult Neural Stem/Progenitor cells response could represent an excellent model to shed light on the neuro-reparative role of adult neurogenesis following damage. The cyclin-dependent kinase inhibitor p21Waf1/Cip1 plays a pivotal role in modulating the quiescence/activation balance of adult Neural Stem Cells (aNSCs) and in restraining the proliferation progression of progenitor cells. Based on these considerations, the aim of this work is to evaluate how the conditional ablation of p21Waf1/Cip1 in the aNSCS can alter the adult hippocampal neurogenesis in physiological and post-traumatic conditions.

METHODS

We designed a novel conditional p21Waf1/Cip1 knock-out mouse model, in which the deletion of p21Waf1/Cip1 (referred as p21) is temporally controlled and occurs in Nestin-positive aNSCs, following administration of Tamoxifen. This mouse model (referred as p21 cKO mice) was subjected to Controlled Cortical Impact to analyze how the deletion of p21 could influence the post-traumatic neurogenic response within the hippocampal niche.

RESULTS

The data demonstrates that the conditional deletion of p21 in the aNSCs induces a strong increase in activation of aNSCs as well as proliferation and differentiation of neural progenitors in the adult dentate gyrus of the hippocampus, resulting in an enhancement of neurogenesis and the hippocampal-dependent working memory. However, following traumatic brain injury, the increased neurogenic response of aNSCs in p21 cKO mice leads to a fast depletion of the aNSCs pool, followed by declined neurogenesis and impaired hippocampal functionality.

CONCLUSIONS

These data demonstrate for the first time a fundamental role of p21 in modulating the post-traumatic hippocampal neurogenic response, by the regulation of the proliferative and differentiative steps of aNSCs/progenitor populations after brain damage.

Omega-3 polyunsaturated fatty acids supplementation improves memory in first-diagnosed, drug-naïve patients with depression: Secondary analysis of data from a randomized controlled trial

INTRODUCTION

Cognitive impairments are found in most patients with major depressive disorder (MDD). It is believed that low Omega-3 polyunsaturated fatty acids (n-3 PUFAs) level raise the risk of anxiety, depressive symptoms and cognition dysfunction. Since our previous research has found n-3 PUFAs supplementation improves anxiety in MDD, this study was to further explore the effectiveness on cognitive impairment among depressed patients.

METHODS

A total of 72 venlafaxine treated outpatients with first-diagnosed, drug-naïve depression were enrolled. Daily n-3 PUFAs supplementation (2.4 g/d of fish oil, including 1440 mg eicosapentaenoic acid and 960 mg of docosahexaenoic acid) or placebo was used for 12 weeks. Cognitive function, measure by repeatable battery for the assessment of neuropsychological status ([RBANS]) scores, was compared over time.

RESULTS

Immediate memory, delayed memory and RBANS total scores were significant higher in both groups at week 4 and week 12 compared with baseline. Both groups exhibited improvement on attention scores at week 12. No significant differences were observed comparing n-3 PUFAs with placebo groups in the improvement of total RBANS scores and other subscales except in the change of immediate memory at both week 4 and week 12 (p < 0.05).

LIMITATIONS

Sample size was relatively low. Moreover, multiple ethnic populations and the income of patients should be considered. Lastly, we used raw scores instead of the standardized scores of RBANS.

CONCLUSION

N-3 PUFAs supplementation yielded a small but statistically significant improvement on immediate memory in first-diagnosed, drug-naïve depressed patients. While, antidepressant treatment resulted in significant improvement of cognitive function.

FALCON systematically interrogates free fatty acid biology and identifies a novel mediator of lipotoxicity

Cellular exposure to free fatty acids (FFAs) is implicated in the pathogenesis of obesity-associated diseases. However, there are no scalable approaches to comprehensively assess the diverse FFAs circulating in human plasma. Furthermore, assessing how FFA-mediated processes interact with genetic risk for disease remains elusive. Here, we report the design and implementation of fatty acid library for comprehensive ontologies (FALCON), an unbiased, scalable, and multimodal interrogation of 61 structurally diverse FFAs. We identified a subset of lipotoxic monounsaturated fatty acids associated with decreased membrane fluidity. Furthermore, we prioritized genes that reflect the combined effects of harmful FFA exposure and genetic risk for type 2 diabetes (T2D). We found that c-MAF-inducing protein (CMIP) protects cells from FFA exposure by modulating Akt signaling. In sum, FALCON empowers the study of fundamental FFA biology and offers an integrative approach to identify much needed targets for diverse diseases associated with disordered FFA metabolism.

FALCON systematically interrogates free fatty acid biology and identifies a novel mediator of lipotoxicity

Cellular exposure to free fatty acids (FFA) is implicated in the pathogenesis of obesity-associated diseases. However, studies to date have assumed that a few select FFAs are representative of broad structural categories, and there are no scalable approaches to comprehensively assess the biological processes induced by exposure to diverse FFAs circulating in human plasma. Furthermore, assessing how these FFA- mediated processes interact with genetic risk for disease remains elusive. Here we report the design and implementation of FALCON (Fatty Acid Library for Comprehensive ONtologies) as an unbiased, scalable and multimodal interrogation of 61 structurally diverse FFAs. We identified a subset of lipotoxic monounsaturated fatty acids (MUFAs) with a distinct lipidomic profile associated with decreased membrane fluidity. Furthermore, we developed a new approach to prioritize genes that reflect the combined effects of exposure to harmful FFAs and genetic risk for type 2 diabetes (T2D). Importantly, we found that c-MAF inducing protein (CMIP) protects cells from exposure to FFAs by modulating Akt signaling and we validated the role of CMIP in human pancreatic beta cells. In sum, FALCON empowers the study of fundamental FFA biology and offers an integrative approach to identify much needed targets for diverse diseases associated with disordered FFA metabolism.

Highlights

FALCON (Fatty Acid Library for Comprehensive ONtologies) enables multimodal profiling of 61 free fatty acids (FFAs) to reveal 5 FFA clusters with distinct biological effectsFALCON is applicable to many and diverse cell typesA subset of monounsaturated FAs (MUFAs) equally or more toxic than canonical lipotoxic saturated FAs (SFAs) leads to decreased membrane fluidityNew approach prioritizes genes that represent the combined effects of environmental (FFA) exposure and genetic risk for diseaseC-Maf inducing protein (CMIP) is identified as a suppressor of FFA-induced lipotoxicity via Akt-mediated signaling.

Ameliorative effects of bromelain on aluminum-induced Alzheimer's disease in rats through modulation of TXNIP pathway

Alzheimer's disease (AD) is known as "type 3 diabetes". As thioredoxin binding protein (TXNIP) has been shown to be involved in brain insulin resistance, the present study evaluated the roles of TXNIP, phospho-insulin receptor substrate 1 (P-IRS-1), and phosphatidyl inositol-3 kinase (PI3K) in the pathogenesis of AD. The potential ameliorative effect of bromelain compared to donepezil was evaluated in an aluminum chloride (AlCl3)-induced AD in rats. Behavioral tests demonstrated similar improvements in exploratory activity, cognitive and spatial memory functions, anxiety, and depression levels between rats treated with bromelain and donepezil. Donepezil was superior to bromelain in improving locomotor activity. Histopathological examinations demonstrated neuronal degeneration in the AlCl3 group that was almost normalized by bromelain and donepezil. Moreover, there was deposition of amyloid plaques in the AlCl3 group that was improved by bromelain and donepezil. Acetylcholine esterase levels were significantly increased in rats treated with AlCl3 group and significantly decreased in rats treated with bromelain and donepezil. Furthermore, AlCl3 group showed a significantly increased TXNIP and P-IRS1 and a significantly reduced PI3K levels. These effects were ameliorated by bromelain and donepezil treatment. The present study demonstrates a previously unreported modulatory effect of bromelain on the TXNIP/P-IRS-1/PI3K axis in AD model.

An SPM-Enriched Marine Oil Supplement Shifted Microglia Polarization toward M2, Ameliorating Retinal Degeneration in rd10 Mice

Retinitis pigmentosa (RP) is the most common inherited retinal dystrophy causing progressive vision loss. It is accompanied by chronic and sustained inflammation, including M1 microglia activation. This study evaluated the effect of an essential fatty acid (EFA) supplement containing specialized pro-resolving mediators (SPMs), on retinal degeneration and microglia activation in rd10 mice, a model of RP, as well as on LPS-stimulated BV2 cells. The EFA supplement was orally administered to mice from postnatal day (P)9 to P18. At P18, the electrical activity of the retina was examined by electroretinography (ERG) and innate behavior in response to light were measured. Retinal degeneration was studied via histology including the TUNEL assay and microglia immunolabeling. Microglia polarization (M1/M2) was assessed by flow cytometry, qPCR, ELISA and histology. Redox status was analyzed by measuring antioxidant enzymes and markers of oxidative damage. Interestingly, the EFA supplement ameliorated retinal dysfunction and degeneration by improving ERG recording and sensitivity to light, and reducing photoreceptor cell loss. The EFA supplement reduced inflammation and microglia activation attenuating M1 markers as well as inducing a shift to the M2 phenotype in rd10 mouse retinas and LPS-stimulated BV2 cells. It also reduced oxidative stress markers of lipid peroxidation and carbonylation. These findings could open up new therapeutic opportunities based on resolving inflammation with oral supplementation with SPMs such as the EFA supplement.

Analysis of the Sequence Preference of Saporin by Deep Sequencing

Ribosome-inactivating proteins (RIPs) are RNA:adenosine glycosidases that inactivate eukaryotic ribosomes by depurinating the sarcin-ricin loop (SRL) in 28S rRNA. The GAGA sequence at the top of the SRL or at the top of a hairpin loop is assumed to be their target motif. Saporin is a RIP widely used to develop immunotoxins for research and medical applications, but its sequence specificity has not been investigated. Here, we combine the conventional aniline cleavage assay for depurinated nucleic acids with high-throughput sequencing to study sequence-specific depurination of oligonucleotides caused by saporin. Our data reveal the sequence preference of saporin for different substrates and show that the GAGA motif is not efficiently targeted by this protein, neither in RNA nor in DNA. Instead, a preference of saporin for certain hairpin DNAs was observed. The observed sequence-specific activity of saporin may be relevant to antiviral or apoptosis-inducing effects of RIPs. The developed method could also be useful for studying the sequence specificity of depurination by other RIPs or enzymes.

Possible antidepressant mechanisms of omega-3 polyunsaturated fatty acids acting on the central nervous system

Omega-3 polyunsaturated fatty acids (PUFAs) can play important roles in maintaining mental health and resistance to stress, and omega-3 PUFAs supplementation can display beneficial effects on both the prevention and treatment of depressive disorders. Although the underlying mechanisms are still unclear, accumulated evidence indicates that omega-3 PUFAs can exhibit pleiotropic effects on the neural structure and function. Thus, they play fundamental roles in brain activities involved in the mood regulation. Since depressive symptoms have been assumed to be of central origin, this review aims to summarize the recently published studies to identify the potential neurobiological mechanisms underlying the anti-depressant effects of omega-3 PUFAs. These include that of (1) anti-neuroinflammatory; (2) hypothalamus-pituitary-adrenal (HPA) axis; (3) anti-oxidative stress; (4) anti-neurodegeneration; (5) neuroplasticity and synaptic plasticity; and (6) modulation of neurotransmitter systems. Despite many lines of evidence have hinted that these mechanisms may co-exist and work in concert to produce anti-depressive effects, the potentially multiple sites of action of omega-3 PUFAs need to be fully established. We also discussed the limitations of current studies and suggest future directions for preclinical and translational research in this field.

Cannabinoid Receptors and Glial Response Following a Basal Forebrain Cholinergic Lesion

The endocannabinoid system modulates learning, memory, and neuroinflammatory processes, playing a key role in neurodegeneration, including Alzheimer's disease (AD). Previous results in a rat lesion model of AD showed modulation of endocannabinoid receptor activity in the basalo-cortical pathway following a specific lesion of basal forebrain cholinergic neurons (BFCNs), indicating that the glial neuroinflammatory response accompanying the lesion is related to endocannabinoid signaling. In this study, 7 days after the lesion, decreased astrocyte and increased microglia immunoreactivities (GFAP and Iba-1) were observed, indicating microglia-mediated neuroinflammation. Using autoradiographic studies, the density and functional coupling to G-proteins of endocannabinoid receptor subtypes were studied in tissue sections from different brain areas where microglia density increased, using CB1 and CB2 selective agonists and antagonists. In the presence of the specific CB1 receptor antagonist, SR141716A, [3H]CP55,940 binding (receptor density) was completely blocked in a dose-dependent manner, while the selective CB2 receptor antagonist, SR144528, inhibited binding to 25%, at best. [35S]GTPγS autoradiography (receptor coupling to Gi/0-proteins) evoked by CP55,940 (CB1/CB2 agonist) and HU308 (more selective for CB2) was abolished by SR141716A in all areas, while SR144528 blocked up to 51.8% of the coupling to Gi/0-proteins evoked by CP55,940 restricted to the nucleus basalis magnocellularis. Together, these results demonstrate that there are increased microglia and decreased astrocyte immunoreactivities 1 week after a specific deletion of BFCNs, which projects to cortical areas, where the CB1 receptor coupling to Gi/0-proteins is upregulated. However, at the lesion site, the area with the highest neuroinflammatory response, there is also a limited contribution of CB2.

Effects of Dietary n-3 LCPUFA Supplementation on the Hippocampus of Aging Female Mice: Impact on Memory, Lipid Raft-Associated Glutamatergic Receptors and Neuroinflammation

Long-chain polyunsaturated fatty acids (LCPUFA), essential molecules whose precursors must be dietary supplied, are highly represented in the brain contributing to numerous neuronal processes. Recent findings have demonstrated that LCPUFA are represented in lipid raft microstructures, where they favor molecular interactions of signaling complexes underlying neuronal functionality. During aging, the brain lipid composition changes affecting the lipid rafts' integrity and protein signaling, which may induce memory detriment. We investigated the effect of a n-3 LCPUFA-enriched diet on the cognitive function of 6- and 15-months-old female mice. Likewise, we explored the impact of dietary n-3 LCPUFAs on hippocampal lipid rafts, and their potential correlation with aging-induced neuroinflammation. Our results demonstrate that n-3 LCPUFA supplementation improves spatial and recognition memory and restores the expression of glutamate and estrogen receptors in the hippocampal lipid rafts of aged mice to similar profiles than young ones. Additionally, the n-3 LCPUFA-enriched diet stabilized the lipid composition of the old mice's hippocampal lipid rafts to the levels of young ones and reduced the aged-induced neuroinflammatory markers. Hence, we propose that n-3 LCPUFA supplementation leads to beneficial cognitive performance by "rejuvenating" the lipid raft microenvironment that stabilizes the integrity and interactions of memory protein players embedded in these microdomains.

A comparative study of the effects of phosphatidylserine rich in DHA and EPA on Aβ-induced Alzheimer's disease using cell models

Alzheimer's disease (AD) is an age-dependent, irreversible neurodegenerative disease, and one of the pathological features is amyloid-β (Aβ) deposition. Previous studies have shown that phosphatidylserine (PS) enriched with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) exhibited significant effects in preventing and alleviating the progress of AD. However, no studies have focused on the differences in the preventive effects on AD between EPA-PS and DHA-PS. Here, the effects of EPA-PS and DHA-PS on Aβ production, Aβ-induced neurotoxicity and Aβ clearance have been studied. The results show that DHA-PS significantly reduced Aβ production in CHO-APP/PS1 cells compared to EPA-PS. Moreover, both EPA-PS and DHA-PS significantly protected the primary hippocampal neurons against Aβ-induced toxicity by inhibiting the mitochondrial-dependent apoptotic pathway and phosphorylation of JNK and p38. Compared to DHA-PS, EPA-PS administration significantly improved the Aβ phagocytic capacity of BV2 cells. In addition, EPA-PS and DHA-PS significantly promoted the neurite outgrowth of primary hippocampal neurons. These findings might provide dietary guidance for the prevention of AD as well as a reference for the development of related functional foods.