Beneficial effects of n-3 polyunsaturated fatty acids administration in a partial lesion model of Parkinson's disease: The role of glia and NRf2 regulation

The Effects and Mechanisms of n-3 and n-6 Polyunsaturated Fatty Acids in the Central Nervous System

The brain is rich in fatty acids (FAs), with polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (C22:6n-3, DHA) and arachidonic acid (C20:4n-6, ARA), and the former predominantly stored in the form of phosphatidylcholine, phosphatidyl ethanolamine (PE, diacyl and plasma phospholipid proform), and phosphatidylserine (PS), while the latter is mainly found in ethanolamine phosphoglycerides (EPG) and contributes to constitute most of phosphoglycerides. When required by the body, PUFAs are liberated from membrane phospholipids (either directly or via their metabolites, which are generated by a series of enzymatic reactions) to participate in various cerebral physiological processes. PUFAs and their derivatives play crucial roles in modulating numerous bodily functions, including neuronal signal transmission, neurogenesis, neuroinflammation, and glucose uptake in the brain, thereby sustaining fundamental brain function. Although PUFAs have been implicated in a spectrum of neurological disorders, including acute brain injury (TBI), multiple sclerosis (MS), and neurodegenerative diseases, their role in conditions such as depression, Alzheimer's disease (AD), and Parkinson's disease (PD) is particularly noteworthy. These disorders are closely linked to critical brain functions, including cognition, memory, and inflammatory processes. Given the substantial body of research elucidating the involvement of PUFAs in the pathogenesis and progression of these diseases, this review will specifically concentrate on their impact within these contexts.

Smoking, coffee intake, and Parkinson's disease: Potential protective mechanisms and components

Parkinson's disease (PD) is a common progressive neurodegenerative disease characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). Environmental and lifestyle factors, such as smoking and coffee drinking, have been associated with a decreased risk for PD. However, the biological mechanisms underlying protective effects on PD are still not fully understood. It has been suggested that non-nicotine components in cigarette smoke and non-caffeine components in coffee may contribute to this protective effect. The aim of this review was to explore candidate molecules and mechanisms behind the effects of smoking and coffee drinking on PD by integrating findings from previous studies. By cross-referencing an index of tobacco constituents and a list of coffee constituents with existing literature on natural compounds and their structural analogs that show inhibitory activities against monoamine oxidase B, catechol O-methyltransferase, and α-synuclein fibrillation, we have identified tobacco and coffee components that inhibit these targets. Furthermore, tobacco and coffee components potentially play roles in suppressing neuroinflammation, activating the Nrf2 pathway as natural activators, and altering the gut microbiome. This review suggests that the phenolic compounds from tobacco and coffee investigated may contribute to the low incidence of PD in smokers and coffee drinkers, showing moderate to strong potential as therapeutic interventions. The current review suggests that multifunctional molecules found in coffee and cigarette smoke may have potential neuroprotective effects, but none of the data indicates that multifunctionality is required for these effects. This review will deepen our understanding of how smoking and coffee drinking are linked to a reduced risk of PD and will also be important in elucidating the mechanisms underlying the protective effects of smoking and coffee drinking on PD.

Exceeding the Limits with Nutraceuticals: Looking Towards Parkinson's Disease and Frailty

One of the most pressing challenges facing society today is the rising prevalence of physical and cognitive frailty. This geriatric condition makes older adults more vulnerable to disability, illness, and a heightened risk of mortality. In this scenario, Parkinson's disease (PD) and geriatric frailty, which share several common characteristics, are becoming increasingly prevalent worldwide, underscoring the urgent need for innovative strategies. Nutraceuticals are naturally occurring bioactive compounds contained in foods, offering health benefits over and above essential nutrition. By examining the literature from the past decade, this review highlights how nutraceuticals can act as complementary therapies, addressing key processes, such as oxidative stress, inflammation, and neuroprotection. Notably, the antioxidant action of nutraceuticals appears particularly beneficial in regard to PD and geriatric frailty. For instance, antioxidant-rich nutraceuticals may mitigate the oxidative damage linked to levodopa therapy in PD, potentially reducing the side effects and enhancing treatment sustainability. Similarly, the antioxidant effects of nutraceuticals may amplify the benefits of physical activity, enhancing muscle function, cognitive health, and resilience, thereby reducing the risk of frailty. This review proposes a holistic approach integrating nutraceuticals with exercise, pharmacotherapy, and lifestyle adjustments. It promises to transform the management of ARD, prolong life, and improve the quality of life and well-being of older people.

Postmortem Fatty Acid Abnormalities in the Cerebellum of Patients with Essential Tremor

Fatty acids play many critical roles in brain function but have not been investigated in essential tremor (ET), a frequent movement disorder suspected to involve cerebellar dysfunction. Here, we report a postmortem comparative analysis of fatty acid profiles by gas chromatography in the cerebellar cortex from ET patients (n = 15), Parkinson's disease (PD) patients (n = 15) and Controls (n = 17). Phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI)/ phosphatidylserine (PS) were separated by thin-layer chromatography and analyzed separately. First, the total amounts of fatty acids retrieved from the cerebellar cortex were lower in ET patients compared with PD patients, including monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA). The diagnosis of ET was associated with lower cerebellar levels of saturated fatty acids (SFA) and PUFA (DHA and ARA) in the PE fraction specifically, but with a higher relative content of dihomo-γ-linolenic acid (DGLA; 20:3 ω-6) in the PC fraction. In contrast, a diagnosis of PD was associated with higher absolute concentrations of SFA, MUFA and ω-6 PUFA in the PI + PS fractions. However, relative PI + PS contents of ω-6 PUFA were lower in both PD and ET patients. Finally, linear regression analyses showed that the ω-3:ω-6 PUFA ratio was positively associated with age of death, but inversely associated with insoluble α-synuclein. Although it remains unclear how these FA changes in the cerebellum are implicated in ET or PD pathophysiology, they may be related to an ongoing neurodegenerative process or to dietary intake differences. The present findings provide a window of opportunity for lipid-based therapeutic nutritional intervention.

Omega-3 polyunsaturated fatty acids and Parkinson's disease: A systematic review of animal studies

Parkinson's disease (PD) is the second most common neurodegenerative disorder. The primary pathological features of PD include the presence of α-synuclein aggregates and Lewy bodies, mitochondrial dysfunction, oxidative stress, and neuroinflammation. Recently, omega-3 fatty acids (ω-3 PUFAs) have been under investigation as a preventive and/or therapeutic strategy for PD, primarily owing to their antioxidant and anti-inflammatory properties. Therefore, the objective of this study was to conduct a systematic review of the literature, focusing on studies that assessed the effects of ω-3 PUFAs in rodent models mimicking human PD. The search was performed using the terms "Parkinson's disease," "fish oil," "omega 3," "docosahexaenoic acid," and "eicosapentaenoic acid" across databases PUBMED, Web of Science, Science Direct, Scielo, and Google Scholar. Following analysis based on predefined inclusion and exclusion criteria, 39 studies were included. Considering behavioral parameters, pathological markers of the disease, quantification of ω-3 PUFAs in the brain, as well as anti-inflammatory, antioxidant, and anti-apoptotic effects, it can be observed that ω-3 PUFAs exhibit a potential neuroprotective effect in PD. In summary, this systematic review presents significant scientific evidence regarding the effects and mechanisms underlying the neuroprotective properties of ω-3 PUFAs, offering valuable insights for the development of future clinical investigations.

Fish oil supplementation, physical activity and risk of incident Parkinson's disease: results of longitudinal analysis from the UK Biobank

Objective

Evidence on the individual and combined relationship of physical activity (PA) and fish oil supplement use on the incidence of Parkinson's disease (PD) risk remains lacking.

Materials and methods

This UK population-based prospective cohort study, involving 385,275 UK Biobank participants, collected PA and fish oil supplement data via touchscreen questionnaires. Using Cox proportional hazards models and restricted cubic splines to examined the associations between use of fish oil supplements, PA and PD risk.

Results

During a median 12.52-year follow-up, 2,131 participants incident PD. Analysis showed that fish oil supplement users had a lower PD risk [hazard ratio (HR), 0.89; 95% confidence interval (CI), 0.82-0.98]. The adjusted HRs for the PD incidence were 0.96 (95% CI, 0.95-0.98) for total PA; 0.93 (95% CI, 0.90-0.96) for moderate PA; 0.95 (95% CI, 0.91-0.99) for vigorous PA and 0.93 (95% CI, 0.89-0.98) for walking activity. Significant interactions were found between fish oil supplement use and total PA (P for interaction = 0.011), moderate PA (P for interaction = 0.015), and walking activity (P for interaction = 0.029) in relation to PD incidence.

Conclusion

Both fish oil supplement use and PA were associated with a reduced risk of PD, and the effect of PA in reducing the risk of PD was more pronounced when fish oil supplement was used.

Metabolic Reprogramming in Gliocyte Post-cerebral Ischemia/ Reperfusion: From Pathophysiology to Therapeutic Potential

Ischemic stroke is a leading cause of disability and death worldwide. However, the clinical efficacy of recanalization therapy as a preferred option is significantly hindered by reperfusion injury. The transformation between different phenotypes of gliocytes is closely associated with cerebral ischemia/ reperfusion injury (CI/RI). Moreover, gliocyte polarization induces metabolic reprogramming, which refers to the shift in gliocyte phenotype and the overall transformation of the metabolic network to compensate for energy demand and building block requirements during CI/RI caused by hypoxia, energy deficiency, and oxidative stress. Within microglia, the pro-inflammatory phenotype exhibits upregulated glycolysis, pentose phosphate pathway, fatty acid synthesis, and glutamine synthesis, whereas the anti-inflammatory phenotype demonstrates enhanced mitochondrial oxidative phosphorylation and fatty acid oxidation. Reactive astrocytes display increased glycolysis but impaired glycogenolysis and reduced glutamate uptake after CI/RI. There is mounting evidence suggesting that manipulation of energy metabolism homeostasis can induce microglial cells and astrocytes to switch from neurotoxic to neuroprotective phenotypes. A comprehensive understanding of underlying mechanisms and manipulation strategies targeting metabolic pathways could potentially enable gliocytes to be reprogrammed toward beneficial functions while opening new therapeutic avenues for CI/RI treatment. This review provides an overview of current insights into metabolic reprogramming mechanisms in microglia and astrocytes within the pathophysiological context of CI/RI, along with potential pharmacological targets. Herein, we emphasize the potential of metabolic reprogramming of gliocytes as a therapeutic target for CI/RI and aim to offer a novel perspective in the treatment of CI/RI.

Brain-wide transcriptome-based metabolic alterations in Parkinson's disease: human inter-region and human-experimental model correlations

Alterations in brain metabolism are closely associated with the molecular hallmarks of Parkinson's disease (PD). A clear understanding of the main metabolic perturbations in PD is therefore important. Here, we retrospectively analysed the expression of metabolic genes from 34 PD-control post-mortem human brain transcriptome data comparisons from literature, spanning multiple brain regions. We found high metabolic correlations between the Substantia nigra (SN)- and cerebral cortex-derived tissues. Moreover, three clusters of PD patient cohorts were identified based on perturbed metabolic processes in the SN - each characterised by perturbations in (a) bile acid metabolism (b) omega-3 fatty acid metabolism, and (c) lipoic acid and androgen metabolism - metabolic themes not comprehensively addressed in PD. These perturbations were supported by concurrence between transcriptome and proteome changes in the expression patterns for CBR1, ECI2, BDH2, CYP27A1, ALDH1B1, ALDH9A1, ADH5, ALDH7A1, L1CAM, and PLXNB3 genes, providing a valuable resource for drug targeting and diagnosis. Also, we analysed 58 PD-control transcriptome data comparisons from in vivo/in vitro disease models and identified experimental PD models with significant correlations to matched human brain regions. Collectively, our findings suggest metabolic alterations in several brain regions, heterogeneity in metabolic alterations between study cohorts for the SN tissues and the need to optimize current experimental models to advance research on metabolic aspects of PD.

Repetitive transcranial magnetic stimulation alleviates glial activation through suppressing HMGB1/TLR4 pathway in a rat model of Parkinson's disease

BACKGROUND

Repetitive transcranial magnetic stimulation (rTMS) has been demonstrated to be effective in Parkinson's disease (PD), but whether rTMS treatment has a relieving effect on neuroinflammation remains to be investigated. In this article, we explored the effects of rTMS on forelimb use asymmetry and neuroinflammation-related mechanisms in a 6-hydroxydopamine (6-OHDA)-induced PD rat model.

METHODS AND RESULTS

Rats in the 6-OHDA+rTMS group received 10 Hz rTMS daily for 4 weeks. Behavioral tests (the cylinder test) were performed at the 3rd and 7th weeks after the operation. Astrocyte and microglia activation and protein levels of tyrosine hydroxylase(TH), high-mobility group box 1(HMGB1) and toll-like receptors 4(TLR4) were investigated by immunohistochemistry and Western blot analyses, respectively. After 4 weeks of treatment, forelimb use asymmetry was ameliorated in the 6-OHDA+rTMS group. Consistent with the behavioral tests, rTMS increased TH in the substantia nigra (SN) and the striatum of PD rats. High glial activation and HMGB1/TLR4 expression in the SN and the striatum were observed in the 6-OHDA group, while rTMS alleviated these changes.

CONCLUSIONS

This study showed that rTMS might be a promising method for alleviating neuroinflammation in PD rat models, and the effects might be mediated through the downregulation of the HMGB1/TLR4 pathway.

A review of studies on gut microbiota and levodopa metabolism

Parkinson's disease (PD) is the second most common neurodegenerative disease globally. Levodopa (L-dopa) has been the cornerstone for treating Parkinson's since the 1960s. However, complications such as "wearing-off" and dyskinesia inevitably appear with disease progression. With the further development of microbiomics in recent years, It has been recognized that gut microbiota plays a crucial role in Parkinson's disease pathogenesis. However, Little is known about the impact of gut microbiota in PD treatment, especially in levodopa metabolism. This review examines the possible mechanisms of gut microbiota, such as Helicobacter pylori, Enterobacter faecalis, and Clostridium sporogenes, affecting L-dopa absorption. Furthermore, we review the current status of gut microbiota intervention strategies, providing new insights into the treatment of PD.

Dietary intake of α-ketoglutarate ameliorates α-synuclein pathology in mouse models of Parkinson's disease

Parkinson's disease (PD) is a progressive movement disorder characterized by dopaminergic (DA) neuron degeneration and the existence of Lewy bodies formed by misfolded α-synuclein. Emerging evidence supports the benefits of dietary interventions in PD due to their safety and practicality. Previously, dietary intake of α-ketoglutarate (AKG) was proved to extend the lifespan of various species and protect mice from frailty. However, the mechanism of dietary AKG's effects in PD remains undetermined. In the present study, we report that an AKG-based diet significantly ameliorated α-synuclein pathology, and rescued DA neuron degeneration and impaired DA synapses in adeno-associated virus (AAV)-loaded human α-synuclein mice and transgenic A53T α-synuclein (A53T α-Syn) mice. Moreover, AKG diet increased nigral docosahexaenoic acid (DHA) levels and DHA supplementation reproduced the anti-α-synuclein effects in the PD mouse model. Our study reveals that AKG and DHA induced microglia to phagocytose and degrade α-synuclein via promoting C1q and suppressed pro-inflammatory reactions. Furthermore, results indicate that modulating gut polyunsaturated fatty acid metabolism and microbiota Lachnospiraceae_NK4A136_group in the gut-brain axis may underlie AKG's benefits in treating α-synucleinopathy in mice. Together, our findings propose that dietary intake of AKG is a feasible and promising therapeutic approach for PD.

Docosahexaenoic acid alleviates the excessive degradation of extracellular matrix in the nucleus pulposus by reducing the content of lncRNA NEAT1 to prevent the progression of intervertebral disc degeneration

The pathogenesis of intervertebral disc degeneration (IVDD), as a multifactorial disease, has not been fully elucidated. However, damage to the stress-bearing system in the intervertebral disc (IVD) mediated by the excessive decomposition of extracellular matrix (ECM) in nucleus pulposus (NP) cells caused by local stimulation is widely considered the core pathological process underlying IVDD. Docosahexaenoic acid (DHA) plays a protective role in various chronic diseases. However, whether it can have such effects in IVDD has not been clearly reported. In recent years, in-depth research on the role of long non-coding RNA (lncRNA) nuclear-enriched transcript 1 (NEAT1) in various diseases has continuously emerged, but such research in the field of IVD is not sufficient. In this study, tert-butyl hydroperoxide (TBHP) was used to induce oxidative stress in human NP cells and construct a cell model of excessive ECM decomposition in vitro. A plasmid over-expressing lncRNA NEAT1 was introduced into human NP cells to establish an NP cell model. For this specific experiment, Cell Counting Kit 8 was used to explore the timing and concentration of DHA and TBHP activity. A common gene chip platform was also used to select potential lncRNAs. Western blot and immunofluorescence assays were used to detect the expression of ECM-related proteins in NP cells in each group. Quantitative real-time polymerase chain reaction was used to detect the expression of lncRNA NEAT1 in NP cells in each group. On this basis, we proved that DHA alleviates excessive degradation of the ECM in NP cells in response to oxidative stress by reducing the content of lncRNA NEAT1. In conclusion, our study reveals the mechanism through which DHA relieves excessive ECM decomposition in NP cells and provides a potential new idea for the treatment of IVDD in clinical practice.

Natural Bioactive Molecules as Neuromedicines for the Treatment/Prevention of Neurodegenerative Diseases

The brain is vulnerable to different types of stresses, particularly oxidative stress as a result of oxygen requirements/utilization in the body. Large amounts of unsaturated fatty acids present in the brain increase this vulnerability. Neurodegenerative diseases (NDDs) are brain disorders that are characterized by the gradual loss of specific neurons and are attributed to broad evidence of cell-level oxidative stress. The accurate characterization of neurological disorders relies on several parameters along with genetics and environmental risk factors, making therapies less efficient to fight NDDs. On the way to tackle oxidative damage and discover efficient and safe therapies, bioactives are at the edge of NDD science. Naturally occurring bioactive compounds such as polyphenols, carotenoids, essential fatty acids, phytosterols, essential oils, etc. are particularly of interest owing to their potent antioxidant and anti-inflammatory activities, and they offer lots of brain-health-promoting features. This Review focuses on probing the neuroefficacy and bioefficacy of bioactives and their role in supporting relatively low antioxidative and low regenerative capacities of the brain, neurogenesis, neuroprotection, and ameliorating/treating NDDs.

Targeting NRF2-KEAP1 axis by Omega-3 fatty acids and their derivatives: Emerging opportunities against aging and diseases

The transcription factor NRF2 and its endogenous inhibitor KEAP1 play a crucial role in the maintenance of cellular redox homeostasis by regulating the gene expression of diverse networks of antioxidant, anti-inflammatory, and detoxification enzymes. Therefore, activation of NRF2 provides cytoprotection against numerous pathologies, including age-related diseases. An age-associated loss of NRF2 function may be a key driving force behind the aging phenotype. Recently, numerous NRF2 inducers have been identified and some of them are promising candidates to restore NRF2 transcriptional activity during aging. Emerging evidence indicates that omega-3 (n-3) polyunsaturated fatty acids (PUFAs) and their electrophilic derivatives may trigger a protective response via NRF2 activation, rescuing or maintaining cellular redox homeostasis. In this review, we provide an overview of the NRF2-KEAP1 system and its dysregulation in aging cells. We also summarize current studies on the modulatory role of n-3 PUFAs as potential agents to prevent multiple chronic diseases and restore the age-related impairment of NRF2 function.

Harnessing the Therapeutic Potential of the Nrf2/Bach1 Signaling Pathway in Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative movement disorder characterized by a progressive loss of dopaminergic neurons in the substantia nigra pars compacta. Although a complex interplay of multiple environmental and genetic factors has been implicated, the etiology of neuronal death in PD remains unresolved. Various mechanisms of neuronal degeneration in PD have been proposed, including oxidative stress, mitochondrial dysfunction, neuroinflammation, α-synuclein proteostasis, disruption of calcium homeostasis, and other cell death pathways. While many drugs individually targeting these pathways have shown promise in preclinical PD models, this promise has not yet translated into neuroprotective therapies in human PD. This has consequently spurred efforts to identify alternative targets with multipronged therapeutic approaches. A promising therapeutic target that could modulate multiple etiological pathways involves drug-induced activation of a coordinated genetic program regulated by the transcription factor, nuclear factor E2-related factor 2 (Nrf2). Nrf2 regulates the transcription of over 250 genes, creating a multifaceted network that integrates cellular activities by expressing cytoprotective genes, promoting the resolution of inflammation, restoring redox and protein homeostasis, stimulating energy metabolism, and facilitating repair. However, FDA-approved electrophilic Nrf2 activators cause irreversible alkylation of cysteine residues in various cellular proteins resulting in side effects. We propose that the transcriptional repressor of BTB and CNC homology 1 (Bach1), which antagonizes Nrf2, could serve as a promising complementary target for the activation of both Nrf2-dependent and Nrf2-independent neuroprotective pathways. This review presents the current knowledge on the Nrf2/Bach1 signaling pathway, its role in various cellular processes, and the benefits of simultaneously inhibiting Bach1 and stabilizing Nrf2 using non-electrophilic small molecules as a novel therapeutic approach for PD.

Effects of Aging and Disease Conditions in Brain of Tumor-Bearing Mice: Evaluation of Purine DNA Damages and Fatty Acid Pool Changes

The consequences of aging and disease conditions in tissues involve reactive oxygen species (ROS) and related molecular alterations of different cellular compartments. We compared a murine model of immunodeficient (SCID) xenografted young (4 weeks old) and old (17 weeks old) mice with corresponding controls without tumor implantation and carried out a compositional evaluation of brain tissue for changes in parallel DNA and lipids compartments. DNA damage was measured by four purine 5',8-cyclo-2'-deoxynucleosides, 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG), and 8-oxo-7,8-dihydro-2'-deoxyadenosine (8-oxo-dA). In brain lipids, the twelve most representative fatty acid levels, which were mostly obtained from the transformation of glycerophospholipids, were followed up during the aging and disease progressions. The progressive DNA damage due to age and tumoral conditions was confirmed by raised levels of 5'S-cdG and 5'S-cdA. In the brain, the remodeling involved a diminution of palmitic acid accompanied by an increase in arachidonic acid, along both age and tumor progressions, causing increases in the unsaturation index, the peroxidation index, and total TFA as indicators of increased oxidative and free radical reactivity. Our results contribute to the ongoing debate on the central role of DNA and genome instability in the aging process, and on the need for a holistic vision, which implies choosing the best biomarkers for such monitoring. Furthermore, our data highlight brain tissue for its lipid remodeling response and inflammatory signaling, which seem to prevail over the effects of DNA damage.

Dual effect of TAT functionalized DHAH lipid nanoparticles with neurotrophic factors in human BBB and microglia cultures

Background

Neurodegenerative diseases (NDs) are an accelerating global health problem. Nevertheless, the stronghold of the brain- the blood–brain barrier (BBB) prevents drug penetrance and dwindles effective treatments. Therefore, it is crucial to identify Trojan horse-like drug carriers that can effectively cross the blood–brain barrier and reach the brain tissue. We have previously developed polyunsaturated fatty acids (PUFA)-based nanostructured lipid carriers (NLC), namely DHAH-NLC. These carriers are modulated with BBB-permeating compounds such as chitosan (CS) and trans-activating transcriptional activator (TAT) from HIV-1 that can entrap neurotrophic factors (NTF) serving as nanocarriers for NDs treatment. Moreover, microglia are suggested as a key causative factor of the undergoing neuroinflammation of NDs. In this work, we used in vitro models to investigate whether DHAH-NLCs can enter the brain via the BBB and investigate the therapeutic effect of NTF-containing DHAH-NLC and DHAH-NLC itself on lipopolysaccharide-challenged microglia.

Methods

We employed human induced pluripotent stem cell-derived brain microvascular endothelial cells (BMECs) to capitalize on the in vivo-like TEER of this BBB model and quantitatively assessed the permeability of DHAH-NLCs. We also used the HMC3 microglia cell line to assess the therapeutic effect of NTF-containing DHAH-NLC upon LPS challenge.

Results

TAT-functionalized DHAH-NLCs successfully crossed the in vitro BBB model, which exhibited high transendothelial electrical resistance (TEER) values (≈3000 Ω*cm²). Specifically, the TAT-functionalized DHAH-NLCs showed a permeability of up to 0.4% of the dose. Furthermore, using human microglia (HMC3), we demonstrate that DHAH-NLCs successfully counteracted the inflammatory response in our cultures after LPS challenge. Moreover, the encapsulation of glial cell-derived neurotrophic factor (GNDF)-containing DHAH-NLCs (DHAH-NLC-GNDF) activated the Nrf2/HO-1 pathway, suggesting the triggering of the endogenous anti-oxidative system present in microglia.

Conclusions

Overall, this work shows that the TAT-functionalized DHAH-NLCs can cross the BBB, modulate immune responses, and serve as cargo carriers for growth factors; thus, constituting an attractive and promising novel drug delivery approach for the transport of therapeutics through the BBB into the brain.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-022-00315-1.

Potential treatment of Parkinson's disease with omega-3 polyunsaturated fatty acids

Parkinson's disease (PD) is characterized by dysfunction of the nigrostriatal system, loss of dopamine neurons and intracellular aggregation of α-synuclein. Recently, both clinical and experimental studies have reported that neuroinflammation and oxidative stress markedly contribute to the etiology of PD. Current clinical pharmacotherapies only temporarily relieve the symptoms of PD, accompanied by many side effects. Hence, searching for natural anti-inflammatory, anti-oxidative and neuroprotective agents has received great attention. Polyunsaturated fatty acids (PUFAs), especially omega (n)-3, are essential lipid nutrients in the human diet and important components of cell membranes. Together by competing with the production of n-6 PUFAs, the precursors of inflammatory mediators, n-3 PUFAs can inhibit microglial activity and neuroinflammation, protect astrocyte function to produce neurotrophins, thereby normalizing neurotransmission and improving neurodegeneration. Thus, with regard to the hypotheses of PD, our and other's recent studies have demonstrated that n-3 PUFAs may improve PD by inhibiting proinflammatory cytokine release, promoting neurotrophic factor expression, recovering mitochondrial function and membrane fluidity, decreasing the levels of oxidant production, maintaining α-synuclein proteostasis, calcium homeostasis, axonal transport, and reducing endoplasmic reticulum stress. This review mainly introduces and analyzes the effect of n-3 PUFA treatments on PD-related behavioral and neuropathological abnormalities in clinical patients and different cellular and animal models of PD. Finally, the limitations and future work in n-3 PUFAs anti-PD area are discussed.

Fundamentals of Membrane Lipid Replacement: A Natural Medicine Approach to Repairing Cellular Membranes and Reducing Fatigue, Pain, and Other Symptoms While Restoring Function in Chronic Illnesses and Aging

Membrane Lipid Replacement (MLR) uses natural membrane lipid supplements to safely replace damaged, oxidized lipids in membranes in order to restore membrane function, decrease symptoms and improve health. Oral MLR supplements contain mixtures of cell membrane glycerolphospholipids, fatty acids, and other lipids, and can be used to replace and remove damaged cellular and intracellular membrane lipids. Membrane injury, caused mainly by oxidative damage, occurs in essentially all chronic and acute medical conditions, including cancer and degenerative diseases, and in normal processes, such as aging and development. After ingestion, the protected MLR glycerolphospholipids and other lipids are dispersed, absorbed, and internalized in the small intestines, where they can be partitioned into circulating lipoproteins, globules, liposomes, micelles, membranes, and other carriers and transported in the lymphatics and blood circulation to tissues and cellular sites where they are taken in by cells and partitioned into various cellular membranes. Once inside cells, the glycerolphospholipids and other lipids are transferred to various intracellular membranes by lipid carriers, globules, liposomes, chylomicrons, or by direct membrane-membrane interactions. The entire process appears to be driven by 'bulk flow' or mass action principles, where surplus concentrations of replacement lipids can stimulate the natural exchange and removal of damaged membrane lipids while the replacement lipids undergo further enzymatic alterations. Clinical studies have demonstrated the advantages of MLR in restoring membrane and organelle function and reducing fatigue, pain, and other symptoms in chronic illness and aging patients.

Effect of Docosahexaenoic Acid (DHA) at the Enteric Level in a Synucleinopathy Mouse Model

The aggregation of alpha-synuclein protein (αSyn) is a hallmark of Parkinson’s disease (PD). Considerable evidence suggests that PD involves an early aggregation of αSyn in the enteric nervous system (ENS), spreading to the brain. While it has previously been reported that omega-3 polyunsaturated fatty acids (ω-3 PUFA) acts as neuroprotective agents in the brain in murine models of PD, their effect in the ENS remains undefined. Here, we studied the effect of dietary supplementation with docosahexaenoic acid (DHA, an ω-3 PUFA), on the ENS, with a particular focus on enteric dopaminergic (DAergic) neurons. Thy1-αSyn mice, which overexpress human αSyn, were fed ad libitum with a control diet, a low ω-3 PUFA diet or a diet supplemented with microencapsulated DHA and then compared with wild-type littermates. Our data indicate that Thy1-αSyn mice showed a lower density of enteric dopaminergic neurons compared with non-transgenic animals. This decrease was prevented by dietary DHA. Although we found that DHA reduced microgliosis in the striatum, we did not observe any evidence of peripheral inflammation. However, we showed that dietary intake of DHA promoted a build-up of ω-3 PUFA-derived endocannabinoid (eCB)-like mediators in plasma and an increase in glucagon-like peptide-1 (GLP-1) and the redox regulator, Nrf2 in the ENS. Taken together, our results suggest that DHA exerts neuroprotection of enteric DAergic neurons in the Thy1-αSyn mice, possibly through alterations in eCB-like mediators, GLP-1 and Nrf2.

Lipids in Pathophysiology and Development of the Membrane Lipid Therapy: New Bioactive Lipids

Membranes are mainly composed of a lipid bilayer and proteins, constituting a checkpoint for the entry and passage of signals and other molecules. Their composition can be modulated by diet, pathophysiological processes, and nutritional/pharmaceutical interventions. In addition to their use as an energy source, lipids have important structural and functional roles, e.g., fatty acyl moieties in phospholipids have distinct impacts on human health depending on their saturation, carbon length, and isometry. These and other membrane lipids have quite specific effects on the lipid bilayer structure, which regulates the interaction with signaling proteins. Alterations to lipids have been associated with important diseases, and, consequently, normalization of these alterations or regulatory interventions that control membrane lipid composition have therapeutic potential. This approach, termed membrane lipid therapy or membrane lipid replacement, has emerged as a novel technology platform for nutraceutical interventions and drug discovery. Several clinical trials and therapeutic products have validated this technology based on the understanding of membrane structure and function. The present review analyzes the molecular basis of this innovative approach, describing how membrane lipid composition and structure affects protein-lipid interactions, cell signaling, disease, and therapy (e.g., fatigue and cardiovascular, neurodegenerative, tumor, infectious diseases).

NRF2 Activation and Downstream Effects: Focus on Parkinson's Disease and Brain Angiotensin

Reactive oxygen species (ROS) are signalling molecules used to regulate cellular metabolism and homeostasis. However, excessive ROS production causes oxidative stress, one of the main mechanisms associated with the origin and progression of neurodegenerative disorders such as Parkinson's disease. NRF2 (Nuclear Factor-Erythroid 2 Like 2) is a transcription factor that orchestrates the cellular response to oxidative stress. The regulation of NRF2 signalling has been shown to be a promising strategy to modulate the progression of the neurodegeneration associated to Parkinson's disease. The NRF2 pathway has been shown to be affected in patients with this disease, and activation of NRF2 has neuroprotective effects in preclinical models, demonstrating the therapeutic potential of this pathway. In this review, we highlight recent advances regarding the regulation of NRF2, including the effect of Angiotensin II as an endogenous signalling molecule able to regulate ROS production and oxidative stress in dopaminergic neurons. The genes regulated and the downstream effects of activation, with special focus on Kruppel Like Factor 9 (KLF9) transcription factor, provide clues about the mechanisms involved in the neurodegenerative process as well as future therapeutic approaches.

The neuromicrobiology of Parkinson's disease: A unifying theory

Recent evidence confirms that PD is indeed a multifactorial disease with different aetiologies and prodromal symptomatology that likely depend on the initial trigger. New players with important roles as triggers, facilitators and aggravators of the PD neurodegenerative process have re-emerged in the last few years, the microbes. Having evolved in association with humans for ages, microbes and their products are now seen as fundamental regulators of human physiology with disturbances in their balance being increasingly accepted to have a relevant impact on the progression of disease in general and on PD in particular. In this review, we comprehensively address early studies that have directly or indirectly linked bacteria or other infectious agents to the onset and progression of PD, from the earliest suspects to the most recent culprits, the gut microbiota. The quest for effective treatments to arrest PD progression must inevitably address the different interactions between microbiota and human cells, and naturally consider the gut-brain axis. The comprehensive characterization of such mechanisms will help design innovative bacteriotherapeutic approaches to selectively shape the gut microbiota profile ultimately to halt PD progression. The present review describes our current understanding of the role of microorganisms and their endosymbiotic relatives, the mitochondria, in inducing, facilitating, or aggravating PD pathogenesis.

Dietary intake and plasma levels of polyunsaturated fatty acids in early-stage Parkinson's disease

Polyunsaturated fatty acids (PUFA) are important for neuronal function and may contribute to the development of neurodegenerative diseases. Here, we investigated the correlation between dietary intake and plasma concentrations of PUFA and their associations with clinical severity in early-stage Parkinson’s disease (PD). In a case–control study with 38 patients with PD and 33 controls, we assessed dietary intake using food frequency questionnaires and simultaneously measured the plasma levels of five PUFA. No differences were observed in dietary total energy and lipid intake, including PUFA, between patients with PD and controls. However, α-linolenic acid (ALA), linoleic acid (LA), and arachidonic acid (AA) plasma levels were lower in patients with PD. The association between dietary intake and plasma PUFA concentrations was not significant in patients with PD. ALA and LA plasma levels were inversely correlated with motor severity in patients with PD, while docosahexaenoic acid and AA plasma levels were positively correlated with non-motor symptoms after controlling for age and sex.

Impact of the apelin/APJ axis in the pathogenesis of Parkinson's disease with therapeutic potential

The pathogenesis of Parkinson's disease (PD) remains elusive. There is still no available disease-modifying strategy against PD, whose management is mainly symptomatic. A growing amount of preclinical evidence shows that a complex interplay between autophagy dysregulation, mitochondrial impairment, endoplasmic reticulum stress, oxidative stress, and excessive neuroinflammation underlies PD pathogenesis. Identifying key molecules linking these pathological cellular processes may substantially aid in our deeper understanding of PD pathophysiology and the development of novel effective therapeutic approaches. Emerging preclinical evidence indicates that apelin, an endogenous neuropeptide acting as a ligand of the orphan G protein-coupled receptor APJ, may play a key neuroprotective role in PD pathogenesis, via inhibition of apoptosis and dopaminergic neuronal loss, autophagy enhancement, antioxidant effects, endoplasmic reticulum stress suppression, as well as prevention of synaptic dysregulation in the striatum, excessive neuroinflammation, and glutamate-induced excitotoxicity. Underlying signaling pathways involve phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin, extracellular signal-regulated kinase 1/2, and inositol requiring kinase 1α/XBP1/C/EBP homologous protein. Herein, we discuss the role of apelin/APJ axis and associated molecular mechanisms on the pathogenesis of PD in vitro and in vivo and provide evidence for its challenging therapeutic potential.

Elovl5 Expression in the Central Nervous System of the Adult Mouse

ELOVL5 (Elongase of Very-Long Fatty Acid 5) gene encodes for an enzyme that elongates long chain fatty acids, with a marked preference for polyunsaturated molecules. In particular, it plays an essential role in the elongation of omega-3 and omega-6 fatty acids, precursors for long-chain polyunsaturated fatty acids (PUFAs). Mutations of ELOVL5 cause the spino-cerebellar ataxia type 38 (SCA38), a rare autosomal neurological disease characterized by gait abnormality, dysarthria, dysphagia, hyposmia and peripheral neuropathy, conditions well represented by a mouse model with a targeted deletion of this gene (Elovl5^–/– mice). However, the expression pattern of this enzyme in neuronal and glial cells of the central nervous system (CNS) is still uninvestigated. This work is aimed at filling this gap of knowledge by taking advantage of an Elovl5-reporter mouse line and immunofluorescence analyses on adult mouse CNS sections and glial cell primary cultures. Notably, Elovl5 appears expressed in a region- and cell type-specific manner. Abundant Elovl5-positive cells were found in the cerebellum, brainstem, and primary and accessory olfactory regions, where mitral cells show the most prominent expression. Hippocampal pyramidal cells of CA2/CA3 where also moderately labeled, while in the rest of the telencephalon Elovl5 expression was high in regions related to motor control. Analysis of primary glial cell cultures revealed Elovl5 expression in oligodendroglial cells at various maturation steps and in microglia, while astrocytes showed a heterogeneous in vivo expression of Elovl5. The elucidation of Elovl5 CNS distribution provides relevant information to understand the physiological functions of this enzyme and its PUFA products, whose unbalance is known to be involved in many pathological conditions.

Dietary nutrition for neurological disease therapy: Current status and future directions

Adequate food intake and relative abundance of dietary nutrients have undisputed effects on the brain function. There is now substantial evidence that dietary nutrition aids in the prevention and remediation of neurologic symptoms in diverse pathological conditions. The newly described influences of dietary factors on the alterations of mitochondrial dysfunction, epigenetic modification and neuroinflammation are important mechanisms that are responsible for the action of nutrients on the brain health. In this review, we discuss the state of evidence supporting that distinct dietary interventions including dietary supplement and dietary restriction have the ability to tackle neurological disorders using Alzheimer's disease, Parkinson's disease, stroke, epilepsy, traumatic brain injury, amyotrophic lateral sclerosis, Huntington's disease and multiple sclerosis as examples. Additionally, it is also highlighting that diverse potential mechanisms such as metabolic control, epigenetic modification, neuroinflammation and gut-brain axis are of utmost importance for nutrient supply to the risk of neurologic condition and therapeutic response. Finally, we also highlight the novel concept that dietary nutrient intervention reshapes metabolism-epigenetics-immunity cycle to remediate brain dysfunction. Targeting metabolism-epigenetics-immunity network will delineate a new blueprint for combating neurological weaknesses.

N-3 PUFA Prevent Oxidative Stress in a Rat Model of Beta-Amyloid-Induced Toxicity

Polyunsaturated fatty acids (PUFA) are involved in brain disorders associated to amyloid beta (Aβ) toxicity for which oxidative stress, neurochemical dysfunctions, and neuroinflammation are underlying mechanisms. Here, mechanisms through which lifelong exposure to n-3 PUFA-enriched or n-6/n-3 balanced diets could elicit a protective role in a rat model of Aβ-induced toxicity were investigated. To this aim, we quantified hippocampal reactive oxygen species (ROS) amount, 8-hydroxy-2'-deoxyguanosine and interleukin-10 levels, NADPH oxidase (NOX) 1, NOX2, superoxide dismutase 1, and glutathione contents, as well as plasmatic malondialdehyde. Moreover, in the same experimental groups, we assessed tryptophan, serotonin, and its turnover, kynurenine, and noradrenaline amounts. Results showed increased hippocampal ROS and NOX2 levels, serotonin turnover, kynurenine, and noradrenaline contents in Aβ-treated rats. Both n-6/n-3 balanced and n-3 PUFA enriched diets reduced ROS production, NOX1 and malondialdehyde levels, serotonin turnover, and kynurenine amount in Aβ-injected rats, while increasing NOX2, superoxide dismutase 1, and serotonin contents. No differences in plasmatic coenzyme Q10, reduced glutathione (GSH) and tryptophan levels were detected among different experimental groups, whereas GSH + oxidized glutathione (GSSG) levels were increased in sham animals fed with n-3 PUFA enriched diet and in Aβ-treated rats exposed to both n-6/n-3 balanced and n-3 enriched diets. In addition, Aβ-induced decrease of interleukin-10 levels was prevented by n-6/n-3 PUFA balanced diet. N-3 PUFA enriched diet further increased interleukin-10 and 8-hydroxy-2'-deoxyguanosine levels. In conclusion, our data highlight the possible neuroprotective role of n-3 PUFA in perturbation of oxidative equilibrium induced by Aβ-administration.

New Avenues for Parkinson's Disease Therapeutics: Disease-Modifying Strategies Based on the Gut Microbiota

Parkinson's disease (PD) is a multifactorial neurodegenerative disorder that currently affects 1% of the population over the age of 60 years, and for which no disease-modifying treatments exist. Neurodegeneration and neuropathology in different brain areas are manifested as both motor and non-motor symptoms in patients. Recent interest in the gut-brain axis has led to increasing research into the gut microbiota changes in PD patients and their impact on disease pathophysiology. As evidence is piling up on the effects of gut microbiota in disease development and progression, another front of action has opened up in relation to the potential usage of microbiota-based therapeutic strategies in treating gastrointestinal alterations and possibly also motor symptoms in PD. This review provides status on the different strategies that are in the front line (i.e., antibiotics; probiotics; prebiotics; synbiotics; dietary interventions; fecal microbiota transplantation, live biotherapeutic products), and discusses the opportunities and challenges the field of microbiome research in PD is facing.

DHA attenuated Japanese Encephalitis virus infection-induced neuroinflammation and neuronal cell death in cultured rat Neuron/glia

Japanese Encephalitis Virus (JEV) is a neurotropic virus and its Central Nervous System (CNS) infection causes fatal encephalitis with high mortality and morbidity. Microglial activation and consequences of bystander damage appear to be the dominant mechanisms for Japanese Encephalitis and complications. Docosahexaenoic acid (DHA), an essential fatty acid and a major component of brain cell membranes, possesses additional biological activities, including anti-apoptosis, anti-inflammation, and neuroprotection. Through this study, we have provided experimental evidence showing the anti-inflammatory, neuroprotective, and anti-viral effects of DHA against JEV infection in rat Neuron/glia cultures. By Neuron/glia and Neuron cultures, DHA protected against neuronal cell death upon JEV infection and reduced JEV amplification. In Neuron/glia and Microglia cultures, the effects of DHA were accompanied by the downregulation of pro-inflammatory M1 microglia, upregulation of anti-inflammatory M2 microglia, and reduction of neurotoxic cytokine expression, which could be attributed to its interference in the Toll-Like Receptor (TLR), Mitogen-Activated Protein Kinase (MAPK), and Interferon/Janus Kinase/Signal Transducers and Activators of Transcription (Stat), along with the NF-κB, AP-1, and c-AMP Response Element Binding Protein (CREB) controlled transcriptional programs. Parallel anti-inflammatory effects against JEV infection were duplicated by G Protein-Coupled Receptor (GPR120) and GPR40 agonists and a reversal of DHA-mediated anti-inflammation was seen in the presence of GPR120 antagonist, while the GPR40 was less effectiveness. Since increasing evidence indicates its neuroprotection against neurodegenerative diseases, DHA is a proposed anti-inflammatory and neuroprotective candidate for the treatment of neuroinflammation-accompanied viral pathogenesis such as Japanese Encephalitis.

Role of polyunsaturated fatty acids in ischemic stroke - A perspective of specialized pro-resolving mediators

Polyunsaturated fatty acids (PUFAs) have been proposed as beneficial for cardiovascular health. However, results from both epidemiological studies and clinical trials have been inconsistent, whereas most of the animal studies showed promising benefits of PUFAs in the prevention and treatment of ischemic stroke. In recent years, it has become clear that PUFAs are metabolized into various types of bioactive derivatives, including the specialized pro-resolving mediators (SPMs). SPMs exert multiple biofunctions, such as to limit excessive inflammatory responses, regulate lipid metabolism and immune cell functions, decrease production of pro-inflammatory factors, increase anti-inflammatory mediators, as well as to promote tissue repair and homeostasis. Inflammation has been recognised as a key contributor to the pathophysiology of acute ischemic stroke. Owing to their potent pro-resolving actions, SPMs are potential for development of novel anti-stroke therapy. In this review, we will summarize current knowledge of epidemiological studies, basic research and clinical trials concerning PUFAs in stroke prevention and treatment, with special attention to SPMs as the unsung heroes behind PUFAs.

Dopaminergic denervation impairs cortical motor and associative/limbic information processing through the basal ganglia and its modulation by the CB1 receptor

The basal ganglia (BG) are involved in cognitive/motivational functions in addition to movement control. Thus, BG segregated circuits, the sensorimotor (SM) and medial prefrontal (mPF) circuits, process different functional domains, such as motor and cognitive/motivational behaviours, respectively. With a high presence in the BG, the CB1 cannabinoid receptor modulates BG circuits. Furthermore, dopamine (DA), one of the principal neurotransmitters in the BG, also plays a key role in circuit functionality. Taking into account the interaction between DA and the endocannabinoid system at the BG level, we investigated the functioning of BG circuits and their modulation by the CB1 receptor under DA-depleted conditions. We performed single-unit extracellular recordings of substantia nigra pars reticulata (SNr) neurons with simultaneous cortical stimulation in sham and 6-hydroxydopamine (6-OHDA)-lesioned rats, together with immunohistochemical assays. We showed that DA loss alters cortico-nigral information processing in both circuits, with a predominant transmission through the hyperdirect pathway in the SM circuit and an increased transmission through the direct pathway in the mPF circuit. Moreover, although DA denervation does not change CB1 receptor density, it impairs its functionality, leading to a lack of modulation. These data highlight an abnormal transfer of information through the associative/limbic domains after DA denervation that may be related to the non-motor symptoms manifested by Parkinson's disease patients.

Contribution of DHA diols (19,20-DHDP) produced by cytochrome P450s and soluble epoxide hydrolase to the beneficial effects of DHA supplementation in the brains of rotenone-induced rat models of Parkinson's disease

Docosahexaenoic acid (DHA) has been shown to have neuroprotective effects in Parkinson's disease, but the underlying mechanism has not been fully elucidated. DHA is metabolized to DHA epoxides (EDPs) and hydroxides by cytochrome P450s (P450s), and EDPs are further hydroxylated to the corresponding diols, dihydroxydocosapentaenoic acids (DHDPs) by soluble epoxide hydrolase (sEH). In the present study, we investigated the roles of these DHA metabolites in the beneficial effects of DHA supplementation on a rotenone-induced rat model of Parkinson's disease. Metabolite analysis by LC-MS revealed that CYP2A1, 2C11, 2C13, 2C23, and 2E1 contributed to the formation of EDPs, and these P450s and sEH were expressed in the rat brain. We found that DHA supplementation in rats improved the motor dysfunction induced by rotenone. In addition, DHA reversed the decrease in tyrosine hydroxylase and the increase in lipid peroxidation generated by rotenone in the striatum. DHA supplementation also induced mRNA expression of antioxidant genes, such as sod1 and catalase, and Nrf2 protein expression in the striatum. However, these effects of DHA supplementation were eliminated by cosupplementation with the sEH inhibitor TPPU. Supplementation with DHA increased the amount of 19,20-DHDP in the rat brain, while the amount of EDPs was not significantly increased. In addition, TPPU suppressed the increase in DHDPs and increased EDPs in the brain. In PC12 cells, 19,20-DHDP increased the mRNA levels of sod1 and catalase along with Nrf2 induction. This study suggests that DHA metabolites-DHDPs generated by P450s and sEH-have an important role in improving rotenone-induced Parkinson's disease.

Oxidative Stress in Parkinson's Disease: Potential Benefits of Antioxidant Supplementation

Parkinson's disease (PD) occurs in approximately 1% of the population over 65 years of age and has become increasingly more common with advances in age. The number of individuals older than 60 years has been increasing in modern societies, as well as life expectancy in developing countries; therefore, PD may pose an impact on the economic, social, and health structures of these countries. Oxidative stress is highlighted as an important factor in the genesis of PD, involving several enzymes and signaling molecules in the underlying mechanisms of the disease. This review presents updated data on the involvement of oxidative stress in the disease, as well as the use of antioxidant supplements in its therapy.

Nanostructured Lipid Carriers Made of Ω-3 Polyunsaturated Fatty Acids: In Vitro Evaluation of Emerging Nanocarriers to Treat Neurodegenerative Diseases

Neurodegenerative diseases (ND) are one of the main problems of public health systems in the 21st century. The rise of nanotechnology-based drug delivery systems (DDS) has become in an emerging approach to target and treat these disorders related to the central nervous system (CNS). Among others, the use of nanostructured lipid carriers (NLCs) has increased in the last few years. Up to today, most of the developed NLCs have been made of a mixture of solid and liquid lipids without any active role in preventing or treating diseases. In this study, we successfully developed NLCs made of a functional lipid, such as the hydroxylated derivate of docohexaenoic acid (DHAH), named DHAH-NLCs. The newly developed nanocarriers were around 100 nm in size, with a polydispersity index (PDI) value of <0.3, and they exhibited positive zeta potential due to the successful chitosan (CS) and TAT coating. DHAH-NLCs were shown to be safe in both dopaminergic and microglia primary cell cultures. Moreover, they exhibited neuroprotective effects in dopaminergic neuron cell cultures after exposition to 6-hydroxydopamine hydrochloride (6-OHDA) neurotoxin and decreased the proinflammatory cytokine levels in microglia primary cell cultures after lipopolysaccharide (LPS) stimuli. The levels of the three tested cytokines, IL-6, IL-1β and TNF-α were decreased almost to control levels after the treatment with DHAH-NLCs. Taken together, these data suggest the suitability of DHAH-NLCs to attaining enhanced and synergistic effects for the treatment of NDs.

Gut Microbiota and Metabolome Alterations Associated with Parkinson's Disease

To our knowledge, this is one of the few studies thus far that correlates the composition of the gut microbiota with the direct analysis of fecal metabolites in patients with Parkinson’s disease. Overall, our data highlight microbiota modifications correlated with numerous fecal metabolites. This suggests that Parkinson’s disease is associated with gut dysregulation that involves a synergistic relationship between gut microbes and several bacterial metabolites favoring altered homeostasis. Interestingly, a reduction of short-chain fatty acid (SCFA)-producing bacteria influenced the shape of the metabolomics profile, affecting several metabolites with potential protective effects in the Parkinson group. On the other hand, the extensive impact that intestinal dysbiosis has at the level of numerous metabolic pathways could encourage the identification of specific biomarkers for the diagnosis and treatment of Parkinson’s disease, also in light of the effect that specific drugs have on the composition of the intestinal microbiota.

Parkinson’s disease is a neurodegenerative disorder characterized by the accumulation of intracellular aggregates of misfolded alpha-synuclein along the cerebral axis. Several studies report the association between intestinal dysbiosis and Parkinson’s disease, although a cause-effect relationship remains to be established. Herein, the gut microbiota composition of 64 Italian patients with Parkinson’s disease and 51 controls was determined using a next-generation sequencing approach. A real metagenomics shape based on gas chromatography-mass spectrometry was also investigated. The most significant changes within the Parkinson’s disease group highlighted a reduction in bacterial taxa, which are linked to anti-inflammatory/neuroprotective effects, particularly in the Lachnospiraceae family and key members, such as Butyrivibrio, Pseudobutyrivibrio, Coprococcus, and Blautia. The direct evaluation of fecal metabolites revealed changes in several classes of metabolites. Changes were seen in lipids (linoleic acid, oleic acid, succinic acid, and sebacic acid), vitamins (pantothenic acid and nicotinic acid), amino acids (isoleucine, leucine, phenylalanine, glutamic acid, and pyroglutamic acid) and other organic compounds (cadaverine, ethanolamine, and hydroxy propionic acid). Most modified metabolites strongly correlated with the abundance of members belonging to the Lachnospiraceae family, suggesting that these gut bacteria correlate with altered metabolism rates in Parkinson’s disease.

IMPORTANCE To our knowledge, this is one of the few studies thus far that correlates the composition of the gut microbiota with the direct analysis of fecal metabolites in patients with Parkinson’s disease. Overall, our data highlight microbiota modifications correlated with numerous fecal metabolites. This suggests that Parkinson’s disease is associated with gut dysregulation that involves a synergistic relationship between gut microbes and several bacterial metabolites favoring altered homeostasis. Interestingly, a reduction of short-chain fatty acid (SCFA)-producing bacteria influenced the shape of the metabolomics profile, affecting several metabolites with potential protective effects in the Parkinson group. On the other hand, the extensive impact that intestinal dysbiosis has at the level of numerous metabolic pathways could encourage the identification of specific biomarkers for the diagnosis and treatment of Parkinson’s disease, also in light of the effect that specific drugs have on the composition of the intestinal microbiota.

Foods with Potential Prooxidant and Antioxidant Effects Involved in Parkinson's Disease

Oxidative stress plays a fundamental role in the pathogenesis of Parkinson's disease (PD). Oxidative stress appears to be responsible for the gradual dysfunction that manifests via numerous cellular pathways throughout PD progression. This review will describe the prooxidant effect of excessive consumption of processed food. Processed meat can affect health due to its high sodium content, advanced lipid oxidation end-products, cholesterol, and free fatty acids. During cooking, lipids can react with proteins to form advanced end-products of lipid oxidation. Excessive consumption of different types of carbohydrates is a risk factor for PD. The antioxidant effects of some foods in the regular diet provide an inconclusive interpretation of the environment's mechanisms with the modulation of oxidation stress-induced PD. Some antioxidant molecules are known whose primary mechanism is the neuroprotective effect. The melatonin mechanism consists of neutralizing reactive oxygen species (ROS) and inducing antioxidant enzyme's expression and activity. N-acetylcysteine protects against the development of PD by restoring levels of brain glutathione. The balanced administration of vitamin B3, ascorbic acid, vitamin D and the intake of caffeine every day seem beneficial for brain health in PD. Excessive chocolate intake could have adverse effects in PD patients. The findings reported to date do not provide clear benefits for a possible efficient therapeutic intervention by consuming the nutrients that are consumed regularly.

β-Asarone Exerts Antioxidative Effects on H2O2-Stimulated PC12 Cells by Activating Nrf2/HO-1 Pathway

Oxidative stress-mediated neuron damage is considered an important contributor to the pathogenesis and development of neurodegenerative diseases. Although β-asarone is widely known for its neuroprotective pharmacological properties, the exact mechanism of β-asarone against oxidative stress has not been fully elucidated. The aim of the present study was to investigate underlying mechanisms of β-asarone against oxidative damage in PC12 cells. Our results demonstrated that the treatment of β-asarone significantly alleviated the reduction in cell viability and the excessive accumulation of lactate dehydrogenase (LDH), malondialdehyde (MDA) and reactive oxygen species (ROS) by increasing the activity of superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH). Moreover, β-asarone pretreatment also activated nuclear factor 2 erythroid-related factor 2 (Nrf2) and its downstream target heme oxygenase-1 (HO-1), which was involved in quenching reactive oxygen to inhibit oxidative stress. Furthermore, when silenced by Nrf2 siRNA, the protective effect of β-asarone was reduced and the oxidative stress induced by H2O2 was enhanced. In conclusion, our findings revealed that β-asarone could reduce oxidative stress via activating Nrf2/HO-1 pathway in PC12 cells, highlighting the potential therapeutic role of β-asarone in neurodegenerative diseases.

Nutraceuticals Targeting Generation and Oxidant Activity of Peroxynitrite May Aid Prevention and Control of Parkinson's Disease

Parkinson's disease (PD) is a chronic low-grade inflammatory process in which activated microglia generate cytotoxic factors-most prominently peroxynitrite-which induce the death and dysfunction of neighboring dopaminergic neurons. Dying neurons then release damage-associated molecular pattern proteins such as high mobility group box 1 which act on microglia via a range of receptors to amplify microglial activation. Since peroxynitrite is a key mediator in this process, it is proposed that nutraceutical measures which either suppress microglial production of peroxynitrite, or which promote the scavenging of peroxynitrite-derived oxidants, should have value for the prevention and control of PD. Peroxynitrite production can be quelled by suppressing activation of microglial NADPH oxidase-the source of its precursor superoxide-or by down-regulating the signaling pathways that promote microglial expression of inducible nitric oxide synthase (iNOS). Phycocyanobilin of spirulina, ferulic acid, long-chain omega-3 fatty acids, good vitamin D status, promotion of hydrogen sulfide production with taurine and N-acetylcysteine, caffeine, epigallocatechin-gallate, butyrogenic dietary fiber, and probiotics may have potential for blunting microglial iNOS induction. Scavenging of peroxynitrite-derived radicals may be amplified with supplemental zinc or inosine. Astaxanthin has potential for protecting the mitochondrial respiratory chain from peroxynitrite and environmental mitochondrial toxins. Healthful programs of nutraceutical supplementation may prove to be useful and feasible in the primary prevention or slow progression of pre-existing PD. Since damage to the mitochondria in dopaminergic neurons by environmental toxins is suspected to play a role in triggering the self-sustaining inflammation that drives PD pathogenesis, there is also reason to suspect that plant-based diets of modest protein content, and possibly a corn-rich diet high in spermidine, might provide protection from PD by boosting protective mitophagy and thereby aiding efficient mitochondrial function. Low-protein diets can also promote a more even response to levodopa therapy.

Beneficial effects of an algal oil rich in ω-3 polyunsaturated fatty acids on locomotor function and D2 dopamine receptor in haloperidol-induced parkinsonism

INTRODUCTION

Parkinson's disease (PD) is a chronic neurological disorder whose pathogenesis involves the loss of dopaminergic neurons and dopamine terminals, formation of Lewy bodies, and microgliosis. Its treatment includes dopamine-based drugs with limited results and adverse effects. Additionally, some neuroleptic drugs used for mental disorders produce side effects referred to as parkinsonism. Dietary interventions with ω-3 polyunsaturated fatty acids (ω-3 PUFA) have attracted attention since they play a key role in most of the processes associated with PD etiology.

OBJECTIVE

The purpose of our work was to investigate the effects of an ω-3 PUFA rich algal oil on locomotive alterations induced by haloperidol and D₂ receptor protein and gene expression in Wistar rats.

METHODOLOGY

Pre- and co-supplementation of algal oil (300 mg of ω-3 FA/kg/day for six weeks) and haloperidol (1.5 mg/kg/day for two weeks) were evaluated.

RESULTS

Haloperidol provoked locomotive alterations in the Open Field Test and a 43% diminution in D₂ receptor in brain membranes; in pre-supplemented rats a 93% increase in D₂ receptor protein expression and a partial maintenance of locomotory performance were observed, while in co-supplemented rats D₂ receptor protein expression was maintained as in control rats, although locomotive behavior was found diminished as in haloperidol rats.

CONCLUSIONS

These results confirm the beneficial effects of ω-3 PUFA over locomotory alterations and as neuroprotective and neurorestorative compounds and demonstrates a stimulatory action on D₂ receptor presence, as a mechanism by which these fatty acids participate in brain health.

Docosahexaenoic acid protects motor function and increases dopamine synthesis in a rat model of Parkinson's disease via mechanisms associated with increased protein kinase activity in the striatum

Parkinson's disease (PD) is a devastating neurodegenerative disease that leads to motor deficits and selective destruction of nigrostriatal dopaminergic neurons. PD is typically treated by dopamine replacement agents; however, dopamine replacement loses effectiveness in the later stages of the disease. Here, we describe the neuroprotective effects of the omega-3 fatty acid docosahexaenoic acid (DHA) in the medial forebrain bundle 6-hydroxydopamine (6-OHDA) model of advanced-stage PD in rats. We show that daily administration of DHA protects against core symptoms of PD, including deficits in postural stability, gait integrity, and dopamine neurochemistry in motor areas of the striatum. Our results also demonstrate that DHA increases striatal dopamine synthesis via phosphorylation of the rate-limiting catecholamine synthesizing enzyme tyrosine hydroxylase, in a manner dependent on the second messenger-linked protein kinases PKA and PKC. We also show that DHA specifically reverses dopamine loss in the nigrostriatal pathway, with no effect in the mesolimbic or mesocortical pathways. This suggests that DHA is unlikely to produce pharmacotherapeutic or adverse effects that depend on dopamine pathways other than the nigrostriatal pathway. To our knowledge, previous reports have not examined the effects of DHA in such an advanced-stage model, documented that the dopamine synthesizing effects of DHA in vivo are mediated through the activation of protein kinases and regulation of TH activity, or demonstrated specificity to the nigrostriatal pathway. These novel findings corroborate the beneficial effects of omega-3 fatty acids seen in PD patients and suggest that DHA provides a novel means of protecting patients for dopamine neurodegeneration.

The effects of Mediterranean diet on severity of disease and serum Total Antioxidant Capacity (TAC) in patients with Parkinson's disease: a single center, randomized controlled trial

Background: Parkinson's disease (PD) as one of the most common neurodegenerative disorders may be affected by healthy dietary pattern. The aim of this study was to investigate the effects of the Mediterranean Diet (MeD) on serum Total Antioxidant Capacity (TAC) and disease severity in PD patients.Materials & Methods: In this single-center randomized clinical trial, patients with idiopathic PD (n = 80) were selected randomly allocated to either MeD or control group (Iranian traditional diet); an individualized dietary plan based on the MeD was designed. Serum TAC and the motor & non-motor disease aspects using the Unified Parkinson's Disease Rating Scale (UPDRS) were evaluated in two groups. Statistical Analysis of data was performed using SPSS 24.Results: 70 PD patients with a mean age of 58.96 ± 8.7 and UDPRS of 41.66 ± 20.19 were analyzed in this study. MeD significantly increased serum TAC (P < 0.001). UPDRS score was also lowered in MeD group (P < 0.05).Conclusions: Mediterranean diet seems to have some benefits in PD. as well, TAC levels can also be affected by MeD. Anyway, further studies are needed to confirm the mentioned outcomes.Trial registration: Iranian Registry of Clinical Trials identifier: IRCT20141108019853N4.

Modification of the content of n-3 highly unsaturated fatty acid, chemical composition, and lipid nutritional indices in the meat of grass carp (Ctenopharyngodon idella) fed alfalfa (Medicago sativa) pellets

A 120-d feeding trial was conducted to determine the effect of alfalfa (Medicago sativa) feeding on growth and chemical composition, fatty acid content, and nutritional and lipid indices of the meat of grass carp (Ctenopharyngodon idella). Two experimental diets were used: alfalfa pellet (AP) diet and artificial grain diet (GD). Final weight, feed conversion rate, and protein efficiency ratio were significantly greater in the GD group (P < 0.05). However, no differences in the length and condition factor were observed. The composition of the meat differed between treatments. The protein content was significantly greater in the AP group (P < 0.05), while the lipid and cholesterol contents were significantly greater in the GD group (P < 0.05). A greater proportion of saturated, n-6 polyunsaturated, and n-6 highly unsaturated fatty acids was obtained in the GD group. The AP group accumulated a greater concentration of eicosapentaenoic (EPA), docosapentaenoic (DPA), and docosahexaenoic (DHA) acids (P < 0.05). The fatty acid composition of the meat determined a significant decrease in the thrombogenicity index and saturation index (S/P) in the AP group (P < 0.05). The Elongase index was greater in the GD group (P < 0.05). In contrast, the AP group had a greater index of Δ9 Desaturase and Δ5 + Δ6 Desaturase for n-3 and n-6 fatty acids (P < 0.05). These results suggest that alfalfa feeding decreases the growth of C. idella but improves the quality of meat by increasing the protein, EPA, and DHA contents. It also reduces cholesterol content and improves nutritional indices.

The Implications for Cells of the Lipid Switches Driven by Protein-Membrane Interactions and the Development of Membrane Lipid Therapy

The cell membrane contains a variety of receptors that interact with signaling molecules. However, agonist-receptor interactions not always activate a signaling cascade. Amphitropic membrane proteins are required for signal propagation upon ligand-induced receptor activation. These proteins localize to the plasma membrane or internal compartments; however, they are only activated by ligand-receptor complexes when both come into physical contact in membranes. These interactions enable signal propagation. Thus, signals may not propagate into the cell if peripheral proteins do not co-localize with receptors even in the presence of messengers. As the translocation of an amphitropic protein greatly depends on the membrane's lipid composition, regulation of the lipid bilayer emerges as a novel therapeutic strategy. Some of the signals controlled by proteins non-permanently bound to membranes produce dramatic changes in the cell's physiology. Indeed, changes in membrane lipids induce translocation of dozens of peripheral signaling proteins from or to the plasma membrane, which controls how cells behave. We called these changes "lipid switches", as they alter the cell's status (e.g., proliferation, differentiation, death, etc.) in response to the modulation of membrane lipids. Indeed, this discovery enables therapeutic interventions that modify the bilayer's lipids, an approach known as membrane-lipid therapy (MLT) or melitherapy.

2-Hydroxy-Docosahexaenoic Acid Is Converted Into Heneicosapentaenoic Acid via α-Oxidation: Implications for Alzheimer's Disease Therapy

Alzheimer’s disease (AD) is a neurodegenerative disease with as yet no efficient therapies, the pathophysiology of which is still largely unclear. Many drugs and therapies have been designed and developed in the past decade to stop or slow down this neurodegenerative process, although none has successfully terminated a phase-III clinical trial in humans. Most therapies have been inspired by the amyloid cascade hypothesis, which has more recently come under question due to the almost complete failure of clinical trials of anti-amyloid/tau therapies to date. To shift the perspective for the design of new AD therapies, membrane lipid therapy has been tested, which assumes that brain lipid alterations lie upstream in the pathophysiology of AD. A hydroxylated derivative of docosahexaenoic acid was used, 2-hydroxy-docosahexaenoic acid (DHA-H), which has been tested in a number of animal models and has shown efficacy against hallmarks of AD pathology. Here, for the first time, DHA-H is shown to undergo α-oxidation to generate the heneicosapentaenoic acid (HPA, C21:5, n-3) metabolite, an odd-chain omega-3 polyunsaturated fatty acid that accumulates in cell cultures, mouse blood plasma and brain tissue upon DHA-H treatment, reaching higher concentrations than those of DHA-H itself. Interestingly, DHA-H does not share metabolic routes with its natural analog DHA (C22:6, n-3) but rather, DHA-H and DHA accumulate distinctly, both having different effects on cell fatty acid composition. This is partly explained because DHA-H α-hydroxyl group provokes steric hindrance on fatty acid carbon 1, which in turn leads to diminished incorporation into cell lipids and accumulation as free fatty acid in cell membranes. Finally, DHA-H administration to mice elevated the brain HPA levels, which was directly and positively correlated with cognitive spatial scores in AD mice, apparently in the absence of DHA-H and without any significant change in brain DHA levels. Thus, the evidence presented in this work suggest that the metabolic conversion of DHA-H into HPA could represent a key event in the therapeutic effects of DHA-H against AD.

Resolution of Inflammation in Neurodegenerative Diseases: The Role of Resolvins

Acute inflammation has been described as a reactive dynamic process, promoted by the secretion of proinflammatory mediators, including lipid molecules like leukotrienes and prostaglandins, and counterbalanced by proresolving mediators including omega-3 polyunsaturated fatty-acid- (PUFA-) derived molecules. The switch from the initiation to the resolution phase of acute inflammatory response is crucial for tissue homeostasis, whereas the failure to resolve early inflammation by specialized proresolving mediators leads to chronic inflammation and tissue damage. Among PUFA-derived proresolving mediators, different eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) derivatives have been described, namely, resolvins (resolution phase interaction products), which exert their anti-inflammatory and immune-regulatory activities through specific G-protein-coupled receptors. In recent years, compelling evidence has shown that impairment of resolution of inflammation is a crucial pathogenic hallmark in different neurodegenerative disorders, including Alzheimer's disease and Parkinson's disease. This review summarizes current knowledge on the role of resolvins in resolution of inflammation and highlights available evidence showing the neuroprotective potential of EPA- and DHA-derived resolvins (E-series and D-series resolvins, respectively) in neurodegenerative diseases.