The Sources of Reactive Oxygen Species and Its Possible Role in the Pathogenesis of Parkinson's Disease

Neuroprotective role of Carvacrol via Nrf2/HO-1/NLRP3 axis in Rotenone-induced PD mice model

Parkinson's disease (PD) is a multifactorial neurodegenerative disorder whose cause is unclear. Neuroinflammation is recognized as one of the major pathogenic mechanisms involved in the development and progression of PD. NLRP3 inflammasome is the most widely studied inflammatory mediator in various diseases including PD. Several phytoconstituents have shown neuroprotective role in PD. Carvacrol is a phenolic monoterpene commonly found in the essential oils derived from plants belonging to Lamiaceae family. It is well known for its anti-inflammatory and antioxidant properties and has been widely explored in several diseases. In this study, we explored the role of Carvacrol in suppressing neuroinflammation by regulating NLRP3 inflammasome through Nrf2/HO-1 axis and subsequently, inflammatory cytokines like IL-1β, IL-18 in Rotenone induced PD mice model. Three doses (25 mg/kg, 50 mg/kg, 100 mg/kg p.o.) of Carvacrol were administered to, respectively, three groups (LD, MD, HD), one hour after administration of Rotenone (1.5 mg/kg, i.p.), every day, for 21 days. Treatment with Carvacrol ameliorated the motor impairment caused by Rotenone. It alleviated neurotoxicity and reduced inflammatory cytokines. Further, Carvacrol also alleviated oxidative stress and increased antioxidant enzymes. From these results, we show that Carvacrol exerts neuroprotective effects in PD via anti-inflammatory and antioxidant mechanisms and could be a potential therapeutic option in PD.

Phospholipidomics in Clinical Trials for Brain Disorders: Advancing our Understanding and Therapeutic Potentials

Phospholipidomics is a specialized branch of lipidomics that focuses on the characterization and quantification of phospholipids. By using sensitive analytical techniques, phospholipidomics enables researchers to better understand the metabolism and activities of phospholipids in brain disorders such as Alzheimer's and Parkinson's diseases. In the brain, identifying specific phospholipid biomarkers can offer valuable insights into the underlying molecular features and biochemistry of these diseases through a variety of sensitive analytical techniques. Phospholipidomics has emerged as a promising tool in clinical studies, with immense potential to advance our knowledge of neurological diseases and enhance diagnosis and treatment options for patients. In the present review paper, we discussed numerous applications of phospholipidomics tools in clinical studies, with a particular focus on the neurological field. By exploring phospholipids' functions in neurological diseases and the potential of phospholipidomics in clinical research, we provided valuable insights that could aid researchers and clinicians in harnessing the full prospective of this innovative practice and improve patient outcomes by providing more potent treatments for neurological diseases.

GUCY2C signaling limits dopaminergic neuron vulnerability to toxic insults

Mitochondrial dysfunction and reactive oxygen species (ROS) accumulation within the substantia nigra pars compacta (SNpc) are central drivers of dopaminergic (DA) neuron death in Parkinson's disease (PD). Guanylyl cyclases and their second messenger cyclic (c)GMP support mitochondrial function, protecting against ROS and promoting cell survival in several tissues. However, the role of the guanylyl cyclase-cGMP axis in defining the vulnerability of DA neurons in the SNpc in PD remains unclear, in part due to the challenge of manipulating cGMP levels selectively in midbrain DA neurons. In that context, guanylyl cyclase C (GUCY2C), a receptor primarily expressed by intestinal epithelial cells, was discovered recently in midbrain DA neurons. Here, we demonstrate that GUCY2C promotes mitochondrial function, reducing oxidative stress and protecting DA neurons from degeneration in the 1-methyl-4-phenyl- 1,2,3,6-tetrahydropyridine (MPTP) mouse model. GUCY2C is overexpressed in the SNpc in PD patients and in mice treated with MPTP, possibly reflecting a protective response to oxidative stress. Moreover, cGMP signaling protects against oxidative stress, mitochondrial impairment, and cell death in cultured DA neurons. These observations reveal a previously unexpected role for the GUCY2C-cGMP signaling axis in controlling mitochondrial dysfunction and toxicity in SNpc DA neurons, highlighting the therapeutic potential of targeting DA neuron GUCY2C to prevent neurodegeneration in PD.

Oxidation of dopamine and related catechols in dopaminergic brain regions in Parkinson's disease and during ageing in non-Parkinsonian subjects

The present study was performed to examine if catechol oxidation is higher in brains from patients with Parkinson's disease compared to age-matched controls, and if catechol oxidation increases with age. Brain tissue from Parkinson patients and age-matched controls was examined for oxidation of dopamine, 3,4-dihydroxyphenylacetic acid (DOPAC) and 3,4-dihydroxyphenylalanine (DOPA) to corresponding quinones, by measurement of 5-S-cysteinyl-dopamine, 5-S-cysteinyl-DOPAC and 5-S-cysteinyl-DOPA. The cysteinyl catechols are assumed to be biomarkers for DA, DOPAC and DOPA autoxidation and part of the biosynthetic pathway of neuromelanin. The concentrations of the 5-S-cysteinyl catechols were lower, whereas the 5-S-cysteinyl-DA/DA and 5-S-cysteinyl-DOPAC/DOPAC ratios tended to be higher in the Parkinson group compared to controls, which was interpreted as a higher degree of oxidation. High 5-S-cysteinyl-DA/DA ratios were found in the substantia nigra of a sub-population of the Parkinson group. Based on 5-S-cysteinyl-DA/DA ratios, dopamine oxidation was found to increase statistically significantly with age in the caudate nucleus, and non-significantly in the substantia nigra. In conclusion, the occurrence of 5-S-cysteinyl-DA, 5-S-cysteinyl-DOPAC and 5-S-cysteinyl-DOPA was demonstrated in dopaminergic brain areas of humans, a tendency for higher oxidation of DA in the Parkinson group compared to controls was observed as well as a statistically significant increase in DA oxidation with age. Possibly, autoxidation of DA and other catechols are involved in both normal and pathological ageing of the brain. This study confirms one earlier but small study, as well as complements one study on non-PD cases and one study on both PD cases and controls on NM bound or integrated markers or catechols.

Diet-gut microbiome interaction and ferulic acid bioavailability: implications on neurodegenerative disorders

PURPOSE OF THE REVIEW

Ferulic acid (FA), which occurs naturally as the feruloylated sugar ester in grains, fruits, and vegetables, is critical for combating oxidative stress and alleviating neurodegenerative diseases resulting from free radical-generated protein aggregates in brain cells. However, FA cannot be absorbed in conjugated form. Therefore, strategies to improve the bioavailability of FA are gaining more importance. Ferulic acid esterases (FAE) of the gut microbiota are critical enzymes that facilitate FA release from feruloylated sugar ester conjugates and influence systemic health. This review provides insight into a nutrition-based approach to preventing neurodegenerative disorders such as Alzheimer's and Parkinson's by altering the diversity of FAE-producing gut microbiota.

RECENT FINDINGS

The human gut is a niche for a highly dense microbial population. Nutrient components and the quality of food shape the gut microbiota. Microbiota-diet-host interaction primarily involves an array of enzymes that hydrolyse complex polysaccharides and release covalently attached moieties, thereby increasing their bio-accessibility. Moreover, genes encoding polysaccharide degrading enzymes are substrate inducible, giving selective microorganisms a competitive advantage in scavenging nutrients. Nutraceutical therapy using specific food components holds promise as a prophylactic agent and as an adjunctive treatment strategy in neurotherapeutics, as it results in upregulation of polysaccharide utilisation loci containing fae genes in the gut microbiota, thereby increasing the release of FA and other antioxidant molecules and combat neurodegenerative processes.

Reactive oxygen species in biological systems: Pathways, associated diseases, and potential inhibitors-A review

Reactive oxygen species (ROS) are produced under normal physiological conditions and may have beneficial and harmful effects on biological systems. ROS are involved in many physiological processes such as differentiation, proliferation, necrosis, autophagy, and apoptosis by acting as signaling molecules or regulators of transcription factors. In this case, maintaining proper cellular ROS levels is known as redox homeostasis. Oxidative stress occurs because of the imbalance between the production of ROS and antioxidant defenses. Sources of ROS include the mitochondria, auto-oxidation of glucose, and enzymatic pathways such as nicotinamide adenine dinucleotide phosphate reduced (NAD[P]H) oxidase. The possible ROS pathways are NF-κB, MAPKs, PI3K-Akt, and the Keap1-Nrf2-ARE signaling pathway. This review covers the literature pertaining to the possible ROS pathways and strategies to inhibit them. Additionally, this review summarizes the literature related to finding ROS inhibitors.

Linking Heat Shock Protein 70 and Parkin in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease that affects millions of elderly people worldwide and is characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The precise mechanisms underlying the pathogenesis of PD are still not fully understood, but it is well accepted that the misfolding, aggregation, and abnormal degradation of proteins are the key causative factors of PD. Heat shock protein 70 (Hsp70) is a molecular chaperone that participates in the degradation of misfolded and aggregated proteins in living cells and organisms. Parkin, an E3 ubiquitin ligase, participates in the degradation of proteins via the proteasome pathway. Recent studies have indicated that both Hsp70 and Parkin play pivotal roles in PD pathogenesis. In this review, we focus on discussing how dysregulation of Hsp70 and Parkin leads to PD pathogenesis, the interaction between Hsp70 and Parkin in the context of PD and their therapeutic applications in PD.

Therapeutic Effects of Geranium Oil in MPTP-Induced Parkinsonian Mouse Model

Parkinson's disease (PD) is an incurable neurodegenerative disease characterized by motor and non-motor disabilities resulting from neuronal cell death in the substantia nigra and striatum. Microglial activation and oxidative stress are two of the primary mechanisms driving that neuronal death. Here, we evaluated the effects of geranium oil on 1-methyl-4-phenyl-1,2,3,6-tetra-hydropyridine (MPTP) mouse model for PD, on microglial activation, and oxidative stress. We demonstrate that oral treatment with geranium oil improved motor performance in this model. The therapeutic effects of geranium oil were observed as a significant increase in rotarod latency and distance among the mice treated with geranium oil, as compared to vehicle-treated MPTP mice. Geranium oil also prevented dopaminergic neuron death in the substantia nigra of the treated mice. These therapeutic effects can be partially attributed to the antioxidant and anti-inflammatory properties of geranium oil, which were observed as attenuated accumulation of reactive oxygen species and inhibition of the secretion of proinflammatory cytokines from geranium oil-treated activated microglial cells. A repeated-dose oral toxicity study showed that geranium oil is not toxic to mice. In light of that finding and since geranium oil is defined by the FDA as generally recognized as safe (GRAS), we do not foresee any toxicity problems in the future and suggest that geranium oil may be a safe and effective oral treatment for PD. Since the MPTP model is only one of the preclinical models for PD, further studies are needed to confirm that geranium oil can be used to prevent or treat PD.

From imbalance to impairment: the central role of reactive oxygen species in oxidative stress-induced disorders and therapeutic exploration

Increased production and buildup of reactive oxygen species (ROS) can lead to various health issues, including metabolic problems, cancers, and neurological conditions. Our bodies counteract ROS with biological antioxidants such as SOD, CAT, and GPx, which help prevent cellular damage. However, if there is an imbalance between ROS and these antioxidants, it can result in oxidative stress. This can cause genetic and epigenetic changes at the molecular level. This review delves into how ROS plays a role in disorders caused by oxidative stress. We also look at animal models used for researching ROS pathways. This study offers insights into the mechanism, pathology, epigenetic changes, and animal models to assist in drug development and disease understanding.

GUCY2C signaling limits dopaminergic neuron vulnerability to toxic insults

Mitochondrial dysfunction and reactive oxygen species (ROS) accumulation within the substantia nigra pars compacta (SNpc) are central drivers of dopaminergic (DA) neuron death in Parkinson's disease (PD). Guanylyl cyclases, and their second messengers cyclic (c)GMP, support mitochondrial function, protecting against ROS and promoting cell survival in a number of tissues. However, the role of the guanylyl cyclase-cGMP axis in defining the vulnerability of DA neurons in the SNpc in PD remains unclear, in part due to the challenge of manipulating cGMP levels selectively in midbrain DA neurons. In that context, guanylyl cyclase C (GUCY2C), a receptor primarily expressed by intestinal epithelial cells, was discovered recently in midbrain DA neurons. Here, we demonstrate that GUCY2C promotes mitochondrial function, reducing oxidative stress and protecting DA neurons from degeneration in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of neurodegeneration. GUCY2C is overexpressed in the SNpc in PD patients and in mice treated with MPTP, possibly reflecting a protective response to oxidative stress. Moreover, cGMP signaling protects against oxidative stress, mitochondrial impairment, and cell death in cultured DA neurons. These observations reveal a previously unexpected role for the GUCY2C-cGMP signaling axis in controlling mitochondrial dysfunction and toxicity in nigral DA neurons, highlighting the therapeutic potential of targeting DA neuron GUCY2C to prevent neurodegeneration in PD.

Loss of DJ-1 function contributes to Parkinson's disease pathogenesis in mice via RACK1-mediated PKC activation and MAO-B upregulation

Parkinson's disease (PD) is a common neurodegenerative motor disorder characterized by a dramatic reduction in pars compacta of substantia nigra dopaminergic neurons and striatal dopamine (DA) levels. Mutations or deletions in the PARK7/DJ-1 gene are associated with an early-onset familial form of PD. DJ-1 protein prevents neurodegeneration via its regulation of oxidative stress and mitochondrial function as well as its roles in transcription and signal transduction. In this study, we investigated how loss of DJ-1 function affected DA degradation, ROS generation and mitochondrial dysfunction in neuronal cells. We showed that loss of DJ-1 significantly increased the expression of monoamine oxidase (MAO)-B but not MAO-A in both neuronal cells and primary astrocytes. In DJ-1-knockout (KO) mice, MAO-B protein levels in the substantia nigra (SN) and striatal regions were significantly increased. We demonstrated that the induction of MAO-B expression by DJ-1 deficiency depended on early growth response 1 (EGR1) in N2a cells. By coimmunoprecipitation omics analysis, we found that DJ-1 interacted with receptor of activated protein C kinase 1 (RACK1), a scaffolding protein, and thus inhibited the activity of the PKC/JNK/AP-1/EGR1 cascade. The PKC inhibitor sotrastaurin or the JNK inhibitor SP600125 completely inhibited DJ-1 deficiency-induced EGR1 and MAO-B expression in N2a cells. Moreover, the MAO-B inhibitor rasagiline inhibited mitochondrial ROS generation and rescued neuronal cell death caused by DJ-1 deficiency, especially in response to MPTP stimulation in vitro and in vivo. These results suggest that DJ-1 exerts neuroprotective effects by inhibiting the expression of MAO-B distributed at the mitochondrial outer membrane, which mediates DA degradation, ROS generation and mitochondrial dysfunction. This study reveals a mechanistic link between DJ-1 and MAO-B expression and contributes to understanding the crosslinks among pathogenic factors, mitochondrial dysfunction and oxidative stress in PD pathogenesis.

Variants in PSMB9 and FGR differentially affect Parkinson's disease risk in GBA and LRRK2 mutation carriers

INTRODUCTION

Recent studies found an association between Parkinson's disease (PD) and alterations in the innate immune system. However, whether the involvement of this system in two of the known genetic forms of PD, GBA-PD and LRRK2-PD, and in patients who do not carry these mutations is different, is yet to be determined. We aimed to test if genetic variations in the innate immune genes are differentially associated with PD in these subgroups.

METHODS

Innate immune genes were identified and classified into sub-lists according to Reactome pathways. Whole-genome-sequencing (WGS) was performed on 201 unrelated Ashkenazi-Jewish (AJ) PD patients including 104 GBA-PD, 32 LRRK2-PD, and 65 non-carriers-PD (NC-PD). To identify genes with different burden between these subgroups of PD, gene-based Sequence kernel association optimal unified test (SKAT-O) analysis was performed on innate immune pathways. Candidate variants within the significant genes were further genotyped in a cohort of 1200 unrelated, consecutively recruited, AJ-PD patients, and to evaluate their association with PD-risk their allele frequencies were compared to AJ-non-neuro cases in gnomAD database, in a stratified and un-stratified manner.

RESULTS

SKAT-O analysis showed significantly different burden for PSMB9 (GBA-PD versus NC-PD) and FGR (GBA-PD versus LRRK2-PD). Two candidate variants in PSMB9 showed an association with GBA-PD-risk and NC-PD-risk while one FGR variant showed an association with LRRK2-PD-risk.

CONCLUSION

Our data supports differential involvement of innate immunity risk alleles in PD and emphasizes the differences between the GBA- and LRRK2-PD subgroups.

Phenolic compounds from the flowers of Rosa hugonis Hemsl. and their neuroprotective effects

The fragrant flowers of Rosa hugonis Hemsl. Contain abundant valuable rose oil and carotenoids. However, phytochemical investigation of this resource rich in phenolics with neuroprotective activity in vitro has been rarely reported. Purification of the 70% ethanol extracts from the flowers of R. hugonis by various chromatographic methods resulted in the isolation and characterization of five undescribed acylated flavonoid glycosides (Hugonisflavonoid A-E) together with forty known phenolics. The chemical structures of the undescribed compounds were elucidated by extensive analysis of their spectroscopic data and chemical methods. All the isolates were found from R. hugonis for the first time and evaluated for their neuroprotective effects on 6-OHDA induced injury in PC12 cells. Seventeen compounds displayed remarkable protective effects at concentrations of 10 μM. Hugonisflavonoid E can reduce excessive reactive oxygen species and up-regulate mRNA expression levels of superoxide dismutase 1 and catalase. Additionally, hugonisflavonoid E activated the phosphorylated proteins such as PDK1, Akt and GSk-3β. These findings suggested that R. hugonis could be a potential source for neuroprotective agents.

Anti-oxidative and anti-neuroinflammatory role of Necrostatin-1s and docosahexaenoic acid in RIP-1-mediated neurotoxicity in MPTP-induced Parkinson's disease model

Parkinson's disease (PD) is a neuromuscular ailment that affects people in their later years and causes both motor and non-motor deficits. Receptor-interacting protein-1 (RIP-1) is a critical participant in necroptotic cell death, possibly through an oxidant-antioxidant imbalance and cytokine cascade activation in PD pathogenesis. The present study examined the role of RIP-1-mediated necroptosis and neuroinflammation in the MPTP-induced PD mouse model, as well as their protection by Necrostatin-1s (an RIP signalling inhibitor), antioxidant DHA and their functional interaction. BALB/c mice were given acute MPTP therapy (4 injections of 15 mg/kg i.p. at 2-h intervals) on day 1. After MPTP intoxication, Necrostatin-1s (Nec-1s; 8 mg/kg/day, i.p.) and DHA (300 mg/kg/day, p.o.) treatments were given once daily for 7 days. The Nec-1s treatment prevented MPTP-induced behavioural, biochemical and neurochemical alterations, and the addition of DHA increases Nec-1s' neuroprotective impact. In addition, Nec-1s and DHA significantly improve the survival of TH-positive dopaminergic neurons and lower expression levels of the inflammatory cytokines, IL-1β and TNF-α. Furthermore, Nec-1s dramatically reduced RIP-1 expression, whereas DHA had little effect. Our research raises the possibility that neuroinflammatory signalling and acute MPTP-induced necroptosis are both mediated by TNFR1-driven RIP-1 activity. In this study, RIP-1 ablation through Nec-1s and the addition of DHA showed a reduction in the levels of pro-inflammatory and oxidative markers, as well as protection from MPTP-driven dopaminergic degeneration and neurobehavioural changes, suggesting potential therapeutic applications. For a better understanding, additional research about the mechanism(s) behind Nec-1s and DHA is required.

<em>Brassica oleracea</em> var. italica extract reducing free radicals and inflammation initiated by an exposure to cigarette smoke

Introduction: Herbal extracts are often administered to cigarette smokers to prevent excessive free radicals. These include Brassica oleracea var. Italica, known to contain high antioxidant flavonoids and selenium micronutrients. Therefore, this study aims to determine the efficacy of Brassica oleracea var extract. italica in reducing the free radicals and inflammation present in experimental animals exposed to cigarette smoke. Design and Methods: This research was conducted based on an experimental method using a randomized controlled trial (RCT) for 21 days. The animals used were divided into six groups (negative control, positive control, and four treatments). Particularly, the positive control and treatment groups were exposed to cigarette smoke for 2 minutes, twice a day, at 50 PPM CO levels. The treatment groups were administered the extract at different doses (0.5 ml; 0.75 ml; 1 ml; 1.25 ml), before assessing the blood level of malondialdehyde and C-Reactive Protein. Result: The results showed the tendency for exposure to smoke to increase the number of free radicals and stimulate inflammation responses in the body (P<0,05). In addition, a strong correlation between variables was established (p=0.000; r=0.713). Conclusions: Broccoli extracts (Brassica oleracea L. var. Italica) administration has the potential to cause a decline in the two aspects, including free radicals and inflammation responses resulting from exposure to cigarette smoke.  

Neuroprotective role of chloroquine via modulation of autophagy and neuroinflammation in MPTP-induced Parkinson's disease

Parkinson's disease (PD) is a neuro-motor ailment that strikes adults in their older life and results in both motor and non-motor impairments. In neuronal and glial cells, PD has recently been linked to a dysregulated autophagic system and cerebral inflammation. Chloroquine (CQ), an anti-malarial drug, has been demonstrated to suppress autophagy in a variety of diseases, including cerebral ischemia, Alzheimer's disease (AD), and Traumatic brain injury (TBI), while its involvement in PD is still unclear. BALB/c mice were randomly allocated to one of four groups: 1-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP), CQ treatment with or without MPTP, or control. The CQ treatment group received CQ (intraperitoneally, 8 mg/kg body weight) after 1 h of MPTP induction on day 1, and it lasted for 7 days. CQ therapy preserves dopamine levels stable, inhibits tyrosine hydroxylase (TH) positive dopaminergic cell death, and lowers oxidative stress. CQ reduces the behavioural, motor, and cognitive deficits caused by MPTP after injury. Furthermore, CQ therapy slowed aberrant neuronal autophagy (microtubule-associated protein-1 light chain 3B; LC3B & Beclin1) and lowered expression levels of the inflammatory cytokines interleukin 1 (IL-1β) and tumour necrosis factor (TNF-α) in the mice brain. In addition, CQ's antioxidant and anti-inflammatory effects were also tested in MPTP-mediated cell death in PC12 cells, demonstrating that CQ has a neurorestorative impact by successfully rescuing MPTP-induced ROS generation and cell loss. Our findings show that CQ's can help to prevent dopaminergic degeneration and improve neurological function after MPTP intoxication by lowering the harmful effects of neuronal autophagy and cerebral inflammation.

The Importance of Dietary Antioxidants on Oxidative Stress, Meat and Milk Production, and Their Preservative Aspects in Farm Animals: Antioxidant Action, Animal Health, and Product Quality-Invited Review

The biological effects of oxidative stress and associated free radicals on farm animal performance, productivity, and product quality may be managed via dietary interventions-specifically, the provision of feeds, supplements, and forages rich in antioxidants. To optimize this approach, it is important first to understand the development of free radicals and their contributions to oxidative stress in tissue systems of farm animals or the human body. The interactions between prooxidants and antioxidants will impact redox homeostasis and, therefore, the well-being of farm animals. The impact of free radical formation on the oxidation of lipids, proteins, DNA, and biologically important macromolecules will likewise impact animal performance, meat and milk quality, nutritional value, and longevity. Dietary antioxidants, endogenous antioxidants, and metal-binding proteins contribute to the 'antioxidant defenses' that control free radical formation within the biological systems. Different bioactive compounds of varying antioxidant potential and bio-accessibility may be sourced from tailored feeding systems. Informed and successful provision of dietary antioxidants can help alleviate oxidative stress. However, knowledge pertaining to farm animals, their unique biological systems, and the applications of novel feeds, specialized forages, bioactive compounds, etc., must be established. This review summarized current research to direct future studies towards more effective controls for free radical formation/oxidative stress in farm animals so that productivity and quality of meat and milk can be optimized.

ATH434 Rescues Pre-motor Hyposmia in a Mouse Model of Parkinsonism

Hyposmia is a prevalent prodromal feature of Parkinson's disease (PD), though the neuropathology that underlies this symptom is poorly understood. Unlike the substantia nigra, the status of metal homeostasis in the olfactory bulbs has not been characterized in PD. Given the increasing interest in metal modulation as a therapeutic avenue in PD, we sought to investigate bulbar metals and the effect of AT434 (formerly PBT434) an orally bioavailable, small molecule modulator of metal homeostasis on hyposmia in a mouse model of parkinsonism (the tau knockout (tau-/-) mouse). 5.5 (pre-hyposmia) and 13.5-month-old (pre-motor) mice were dosed with ATH434 (30 mg/kg/day, oral gavage) for 6 weeks. Animals then underwent behavioral analysis for olfactory and motor phenotypes. The olfactory bulbs and the substantia nigra were then collected and analyzed for metal content, synaptic markers, and dopaminergic cell number. ATH434 was able to prevent the development of hyposmia in young tau-/- mice, which coincided with a reduction in bulbar iron and copper levels, an increase in synaptophysin, and a reduction in soluble α-synuclein. ATH434 was able to prevent the development of motor impairment in aged tau-/- mice, which coincided with a reduction in iron levels and reduced neurodegeneration in the substantia nigra. These data implicate metal dyshomeostasis in parkinsonian olfactory deficits, and champion a potential clinical benefit of ATH434 in both prodromal and clinical stages of PD.

Oxidative Stress and Emergence of Psychosis

Treatment and prevention strategies for schizophrenia require knowledge about the mechanisms involved in the psychotic transition. Increasing evidence suggests a redox imbalance in schizophrenia patients. This narrative review presents an overview of the scientific literature regarding blood oxidative stress markers’ evolution in the early stages of psychosis and chronic patients. Studies investigating peripheral levels of oxidative stress in schizophrenia patients, first episode of psychosis or UHR individuals were considered. A total of 76 peer-reviewed articles published from 1991 to 2022 on PubMed and EMBASE were included. Schizophrenia patients present with increased levels of oxidative damage to lipids in the blood, and decreased levels of non-enzymatic antioxidants. Genetic studies provide evidence for altered antioxidant functions in patients. Antioxidant blood levels are decreased before psychosis onset and blood levels of oxidative stress correlate with symptoms severity in patients. Finally, adjunct treatment of antipsychotics with the antioxidant N-acetyl cysteine appears to be effective in schizophrenia patients. Further studies are required to assess its efficacy as a prevention strategy. Redox imbalance might contribute to the pathophysiology of emerging psychosis and could serve as a therapeutic target for preventive or adjunctive therapies, as well as biomarkers of disease progression.

Apolipoprotein A-I mimetic peptides (ApoAI MP) improve oxidative stress and inflammatory responses in Parkinson’s disease mice

Purpose: Parkinson’s disease (PD) is closely associated with oxidative stress and inflammatory situation. Apolipoprotein A-I mimetic peptides (ApoAI MP) have antioxidant and anti-inflammatory properties. We aimed to study the therapeutic effect of ApoAI MP on PD mice, and to explore the related mechanisms.

Methods: PD mice were induced by using 1-methyl-4-phenyl-1,2,3,6-tetrathydropyridine (MPTP). The model mice were treated with different concentrations of ApoAI MP. The open-field behavioral test assesses the total distance moved, the rest time, and the number of crossings and Rota-rod was used to evaluate motor coordination. Oxidative stress was identified by measuring the levels of superoxide dismutase (SOD), catalase (CAT), glutathionperoxidase (GSH-Px), malondialdehyde, ROS and H2O2. Inflammatory situation was analyzed by measuring the levels of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6). Meanwhile, the scavenging activities of ApoAI MP for ABTS, DPPH, hydroxyl radical and superoxide anion, and the effects of the peptide on neurotransmitters were evaluated.

Results: PD model establishment increased oxidative stress and inflammatory status by increasing the concentrations of ROS and H2O2 production, and the levels of TNF-α, IL-1β and IL-6 (p &lt; 0.05). ApoAI MP intervention improved PD symptoms by reducing the total moved distance and the number of passes (p &lt; 0.01), and the falling times from Rota-rod, and increasing rest time (p &lt; 0.05). ApoAI MP increased antioxidant properties by increasing the activities of SOD, CAT and GSH-Px, and reducing MDA concentration (p &lt; 0.05). ApoAI MP addition reduced oxidative stress by scavenging ABTS, DPPH, hydroxyl radicals and superoxide anion and reducing the concentrations of ROS and H2O2 production (p &lt; 0.05). ApoAI MP treatment increased anti-inflammatory capacities by reducing the concentrations of TNF-α, IL-1β and IL-6 (p &lt; 0.05). HPLC analysis showed that the peptide treatment improved neurotransmitters.

Conclusion: ApoAI MP can improve the behavioral performance of PD mice by improving antioxidant and anti-inflammatory capacities.

The Hidden Notes of Redox Balance in Neurodegenerative Diseases

Reactive oxygen species (ROS) are versatile molecules that, even if produced in the background of many biological processes and responses, possess pleiotropic roles categorized in two interactive yet opposite domains. In particular, ROS can either function as signaling molecules that shape physiological cell functions, or act as deleterious end products of unbalanced redox reactions. Indeed, cellular redox status needs to be tightly regulated to ensure proper cellular functioning, and either excessive ROS accumulation or the dysfunction of antioxidant systems can perturb the redox homeostasis, leading to supraphysiological concentrations of ROS and potentially harmful outcomes. Therefore, whether ROS would act as signaling molecules or as detrimental factors strictly relies on a dynamic equilibrium between free radical production and scavenging resources. Of notice, the mammalian brain is particularly vulnerable to ROS-mediated toxicity, because it possesses relatively poor antioxidant defenses to cope with the redox burden imposed by the elevated oxygen consumption rate and metabolic activity. Many features of neurodegenerative diseases can in fact be traced back to causes of oxidative stress, which may influence both the onset and progression of brain demise. This review focuses on the description of the dual roles of ROS as double-edge sword in both physiological and pathological settings, with reference to Alzheimer's and Parkinson's diseases.

Relative quantification of sulfenic acids in plasma proteins using differential labelling and mass spectrometry coupled with 473 nm photo-dissociation analysis: A multiplexed approach applied to an Alzheimer's disease cohort

Cysteine (Cys) is subject to a variety of reversible post-translational modifications such as formation of sulfenic acid (Cys-SOH). If this modification is often involved in normal biological activities, it can also be the result of oxidative damage. Indeed, oxidative stress yields abnormal cysteine oxidations that affect protein function and structure and can lead to neurodegenerative diseases. In a context of population ageing, validation of novel biomarkers for detection of neurodegenerative diseases is important. However, Cys-SOH proteins investigation in large human cohorts is challenging due to their low abundance and lability under endogenous conditions. To improve the detection specificity towards the oxidized protein subpopulation, we developed a method that makes use of a mass spectrometer coupled with visible laser induced dissociation (LID) to add a stringent optical specificity to the mass selectivity. Since peptides do not naturally absorb in the visible range, this approach relies on the proper chemical derivatization of Cys-SOH with a chromophore functionalized with a cyclohexanedione. To compensate for the significant variability in total protein expression within the samples and any experimental bias, a normalizing strategy using free thiol (Cys-SH) cysteine peptides derivatized with a maleimide chromophore as internal references was used. Thanks to the differential tagging, oxidative ratios were then obtained for 69 Cys-containing peptides from 19 proteins tracked by parallel reaction monitoring (PRM) LID, in a cohort of 49 human plasma samples from Alzheimer disease (AD) patients. A statistical analysis indicated that, for the proteins monitored, the Cys oxidative ratio does not correlate with the diagnosis of AD. Nevertheless, the PRM-LID method allows the unbiased, sensitive and robust relative quantification of Cys oxidation within cohorts of samples.

Dose Dependent Effects of Breynia cernua Against the Paraquat Induced Parkinsonism like Symptoms in Animals' Model: In Vitro, In Vivo and Mechanistic Studies

The aims and objectives of the study were to evaluate the antiParkinson's (PD) potential of B cernua (BCE). B cernua (Poir.) Müll. Arg. (B cernua) is a member of the Phyllanthaceae family. HPLC revealed the presence of various phytochemicals. Study was conducted for 40 days. After PD induction by paraquat behavioural studies were carried out. Biochemical parameters such as DPPH, NO-scavenging, Ferrous reducing power, MDA, GSH, CAT, SOD, acetylcholinesterase (AChE), neurotransmitter estimation and TNF-α and IL-6 levels were determined. DPPH, NO-scavenging and Ferrous reducing power assays showed 78.02%, 48.05% and 71.45% inhibitions, respectively. There was significant improvement in motor functions and coordination in a dose-dependent manner (50 < 250 < 500 mg/kg) in PD rat model. Biochemical markers; SOD, CAT, GPx and GSH showed significant restoration (P < .001) while MDA showed significant decrease (P < .05). The AChE level was significantly reduced (P < .05) at 500 mg/kg while neurotransmitters were significantly improved (P < .001) in a dose-dependent fashion. The ELISA results showed significant (P < .001) down-regulation of IL-6 and TNF-α level. In conclusion, it is suggested that BCE has the potential to reduce the symptoms of PD.

Neuronal-Immune Cell Units in Allergic Inflammation in the Nose

Immune cells and immune-derived molecules, endocrine glands and hormones, the nervous system and neuro molecules form the combined tridirectional neuroimmune network, which plays a significant role in the communication pathways and regulation at the level of the whole organism and local levels, in both healthy persons and patients with allergic rhinitis based on an allergic inflammatory process. This review focuses on a new research paradigm devoted to neuronal-immune cell units, which are involved in allergic inflammation in the nose and neuroimmune control of the nasal mucociliary immunologically active epithelial barrier. The categorization, cellular sources of neurotransmitters and neuropeptides, and their prevalent profiles in constituting allergen tolerance maintenance or its breakdown are discussed. Novel data on the functional structure of the nasal epithelium based on a transcriptomic technology, single-cell RNA-sequencing results, are considered in terms of neuroimmune regulation. Notably, the research of pathogenesis and therapy for atopic allergic diseases, including recently identified local forms, from the viewpoint of the tridirectional interaction of the neuroimmune network and discrete neuronal-immune cell units is at the cutting-edge.

A Critical Review of Zebrafish Models of Parkinson's Disease

A wide variety of human diseases have been modelled in zebrafish, including various types of cancer, cardiovascular diseases and neurodegenerative diseases like Alzheimer’s and Parkinson’s. Recent reviews have summarized the currently available zebrafish models of Parkinson’s Disease, which include gene-based, chemically induced and chemogenetic ablation models. The present review updates the literature, critically evaluates each of the available models of Parkinson’s Disease in zebrafish and compares them with similar models in invertebrates and mammals to determine their advantages and disadvantages. We examine gene-based models, including ones linked to Early-Onset Parkinson’s Disease: PARKIN, PINK1, DJ-1, and SNCA; but we also examine LRRK2, which is linked to Late-Onset Parkinson’s Disease. We evaluate chemically induced models like MPTP, 6-OHDA, rotenone and paraquat, as well as chemogenetic ablation models like metronidazole-nitroreductase. The article also reviews the unique advantages of zebrafish, including the abundance of behavioural assays available to researchers and the efficiency of high-throughput screens. This offers a rare opportunity for assessing the potential therapeutic efficacy of pharmacological interventions. Zebrafish also are very amenable to genetic manipulation using a wide variety of techniques, which can be combined with an array of advanced microscopic imaging methods to enable in vivo visualization of cells and tissue. Taken together, these factors place zebrafish on the forefront of research as a versatile model for investigating disease states. The end goal of this review is to determine the benefits of using zebrafish in comparison to utilising other animals and to consider the limitations of zebrafish for investigating human disease.

Diverse and Complementary Effects of Ghrelin and Obestatin

Ghrelin and obestatin are two “sibling proteins” encoded by the same preproghrelin gene but possess an array of diverse and complex functions. While there are ample literature documenting ghrelin’s functions, the roles of obestatin are less clear and controversial. Ghrelin and obestatin have been perceived to be antagonistic initially; however, recent studies challenge this dogma. While they have opposing effects in some systems, they function synergistically in other systems, with many functions remaining debatable. In this review, we discuss their functional relationship under three “C” categories, namely complex, complementary, and contradictory. Their functions in food intake, weight regulation, hydration, gastrointestinal motility, inflammation, and insulin secretion are complex. Their functions in pancreatic beta cells, cardiovascular, muscle, neuroprotection, cancer, and digestive system are complementary. Their functions in white adipose tissue, thermogenesis, and sleep regulation are contradictory. Overall, this review accumulates the multifaceted functions of ghrelin and obestatin under both physiological and pathological conditions, with the intent of contributing to a better understanding of these two important gut hormones.

The Protective Effect of a Unique Mix of Polyphenols and Micronutrients against Neurodegeneration Induced by an In Vitro Model of Parkinson’s Disease

Parkinson’s disease (PD) is second-most common disabling neurological disorder worldwide, and unfortunately, there is not yet a definitive way to prevent it. Polyphenols have been widely shown protective efficacy against various PD symptoms. However, data on their effect on physio-pathological mechanisms underlying this disease are still lacking. In the present work, we evaluated the activity of a mixture of polyphenols and micronutrients, named A5⁺, in the murine neuroblastoma cell line N1E115 treated with 6-Hydroxydopamine (6-OHDA), an established neurotoxic stimulus used to induce an in vitro PD model. We demonstrate that a pretreatment of these cells with A5⁺ causes significant reduction of inflammation, resulting in a decrease in pro-inflammatory cytokines (IFN-γ, IL-6, TNF-α, and CXCL1), a reduction in ROS production and activation of extracellular signal-regulated kinases (ERK)1/2, and a decrease in apoptotic mechanisms with the related increase in cell viability. Intriguingly, A5⁺ treatment promoted cellular differentiation into dopaminergic neurons, as evident by the enhancement in the expression of tyrosine hydroxylase, a well-established dopaminergic neuronal marker. Overall, these results demonstrate the synergic and innovative efficacy of A5⁺ mixture against PD cellular pathological processes, although further studies are needed to clarify the mechanisms underlying its beneficial effect.

Pathophysiology of Lipid Droplets in Neuroglia

In recent years, increasing evidence regarding the functional importance of lipid droplets (LDs), cytoplasmic storage organelles in the central nervous system (CNS), has emerged. Although not abundantly present in the CNS under normal conditions in adulthood, LDs accumulate in the CNS during development and aging, as well as in some neurologic disorders. LDs are actively involved in cellular lipid turnover and stress response. By regulating the storage of excess fatty acids, cholesterol, and ceramides in addition to their subsequent release in response to cell needs and/or environmental stressors, LDs are involved in energy production, in the synthesis of membranes and signaling molecules, and in the protection of cells against lipotoxicity and free radicals. Accumulation of LDs in the CNS appears predominantly in neuroglia (astrocytes, microglia, oligodendrocytes, ependymal cells), which provide trophic, metabolic, and immune support to neuronal networks. Here we review the most recent findings on the characteristics and functions of LDs in neuroglia, focusing on astrocytes, the key homeostasis-providing cells in the CNS. We discuss the molecular mechanisms affecting LD turnover in neuroglia under stress and how this may protect neural cell function. We also highlight the role (and potential contribution) of neuroglial LDs in aging and in neurologic disorders.

An Interactive Review on the Role of Tocotrienols in the Neurodegenerative Disorders

Neurodegenerative disorders, such as Parkinson's and Alzheimer's disease, are claimed to be of major concern causing a significant disease burden worldwide. Oxidative stress, mitochondrial dysfunction and nerve damage are the main reasons for the emergence of these diseases. The formation of reactive oxygen species (ROS) is the common chemical molecule that is formed from all these three interdependent mechanisms which is highly reactive toward the neuronal cells. For these reasons, the administration of tocotrienols (T3s), which is a potent antioxidant, is proven to cater to this problem, through in vitro and in vivo investigations. Interestingly, their therapeutic potentials are not only limited to antioxidant property but also to being able to reverse the neuronal damage and act as a shield for mitochondria dysfunction. Thereby, T3s prevents the damage to the neurons. In regards to this statement, in this review, we focused on summarizing and discussing the potential therapeutic role of T3s on Alzheimer's and Parkinson's diseases, and their protective mechanisms based on evidence from the in vitro and in vivo studies. However, there is no clinical trial conducted to prove the efficacy of T3s for Alzheimer's and Parkinson's subjects. As such, the therapeutic role of T3s for these neurodegenerative disorders is still under debate.

Influence of fruit-based beverages on efficacy of Lacticaseibacillus rhamnosus GG (Lactobacillus rhamnosus GG) against DSS-induced intestinal inflammation

Different lines of evidences from clinical, epidemiological and biochemical studies have established that optimal nutrition including probiotic and fruit phenolics can mitigate the risk and morbidity associated with some chronic diseases. The basis for this observation is the potential synergies that may exist between probiotic strains and different bioactive components of food matrices. This study was conceptualized to compare the efficiency of a probiotic strain in two different fruit matrices. Two fruits, viz., sea buckthorn (Hippophae rhamnoides) (SBT) and apples (Malus pumila) (APJ) were chosen and the anti-inflammatory effects of L. rhamnosus GG (ATCC 53103) (LR) fortified in SBT and APJ were analysed against dextran sulphate sodium (DSS) induced colitis in zebrafish (Danio rerio). The results showed that administration of probiotic (LR) fortified, malt supplemented SBT beverage (SBT + M + LR) had better restorative potential on the intestinal barrier function and mucosal damage, in comparison to LR fortified, malt supplemented APJ beverage (APJ + M + LR). SBT + M + LR demonstrated adequate anti-oxidant potential by enhancing the CAT, SOD, GPx and GSH activities, impaired due to DSS administration. The increase in the expressions of toll like receptor (TLR)-2, TLR-4 and TLR-5 induced by DSS were significantly inhibited by SBT + M + LR administration. Gene expression of pro-inflammatory markers, (NF-κB, TNF-α, IL-1β, IL-6, IL-8, CCL20, MPO and MMP9) were attenuated by SBT + M + LR treatment in intestinal tissues of DSS-treated zebrafishes. Notably, SBT + M + LR increased the expression of anti-inflammatory cytokine, IL-10. The study provides evidence that specific interactions between fruit matrix and probiotic strain can provide adjunct therapeutic strategy to manage intestinal inflammation.

All Roads Lead to Rome: Different Molecular Players Converge to Common Toxic Pathways in Neurodegeneration

Multiple neurodegenerative diseases (NDDs) such as Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS) and Huntington’s disease (HD) are being suggested to have common cellular and molecular pathological mechanisms, characterized mainly by protein misfolding and aggregation. These large inclusions, most likely, represent an end stage of a molecular cascade; however, the soluble misfolded proteins, which take part in earlier steps of this cascade, are the more toxic players. These pathological proteins, which characterize each specific disease, lead to the selective vulnerability of different neurons, likely resulting from a combination of different intracellular mechanisms, including mitochondrial dysfunction, ER stress, proteasome inhibition, excitotoxicity, oxidative damage, defects in nucleocytoplasmic transport, defective axonal transport and neuroinflammation. Damage within these neurons is enhanced by damage from the nonneuronal cells, via inflammatory processes that accelerate the progression of these diseases. In this review, while acknowledging the hallmark proteins which characterize the most common NDDs; we place specific focus on the common overlapping mechanisms leading to disease pathology despite these different molecular players and discuss how this convergence may occur, with the ultimate hope that therapies effective in one disease may successfully translate to another.

Identifying the Effects of Reactive Oxygen Species on Mitochondrial Dynamics and Cytoskeleton Stability in Dictyostelium discoideum

Defects in mitochondrial dynamics, fission, fusion, and motility have been implicated in the pathogenesis of multiple neurodegenerative diseases, including Parkinson's disease, Alzheimer's disease, Huntington's disease, and Charcot-Marie-Tooth disease. Another key feature of neurodegeneration is the increase in reactive oxygen species (ROS). Previous work has shown that the cytoskeleton, in particular the microtubules, and ROS generated by rotenone significantly regulate mitochondrial dynamics in Dictyostelium discoideum. The goal of this project is to study the effects of ROS on mitochondrial dynamics within our model organism D. discoideum to further understand the underlying issues that are the root of neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. We chose three likely ROS inducers, cumene hydroperoxide, hydroxylamine hydrochloride, and Antimycin A. Our work demonstrates that alteration of the microtubule cytoskeleton is not required to alter dynamics in response to ROS and there is no easy way to predict how mitochondrial dynamics will be altered based on which ROS generator is used. This research contributes to the better understanding of the cellular mechanisms that induce the pathogenesis of incurable neurodegenerative diseases with the hope that it will translate into developing new and more effective treatments for patients afflicted by them.

Activation of Nrf2 by methylene blue is associated with the neuroprotection against MPP+ induced toxicity via ameliorating oxidative stress and mitochondrial dysfunction

The neuropathological hallmark of Parkinson's disease (PD) is the preferential loss of dopaminergic neurons in the substantia nigra and presence of Lewy bodies in the dying neurons. Though specific molecular mechanisms for the neurodegeneration remains to be clarified, mitochondrial dysfunction and increased oxidative stress are major players associated with PD pathogenesis and these pathogenic mechanisms can be reproduced in cells and animals by application of various neurotoxins such as MPP⁺. In this study, we attempted to determine the neuroprotective effects of methylene blue (MB) against 1-methyl-4-phenylpyridinium (MPP⁺)-induced neurotoxicity, and to elucidate its action mechanism. We observed that MB attenuated MPP⁺-induced apoptotic cell death in SH-SY5Y cells and the mescencephalic dopaminergic neurons. In addition, MB protected the cells against MPP⁺-induced oxidative stress and mitochondrial dysfunction as evidenced by restoration of mitochondrial complex I activity and ATP levels, and attenuation of oxidative stress. Moreover, we demonstrated that MB induced antioxidant molecules, and activated Nrf2 pathway through AKT activation. These results indicate that MB protects the neurons from MPP⁺-induced toxicity through activation of antioxidant system, thereby reducing the oxidative stress and mitochondrial impairment, implying the potential use of MB in the treatment of neurodegenerative diseases such as PD.

Hypoxia Signaling in Parkinson's Disease: There Is Use in Asking "What HIF?"

Hypoxia is a condition characterized by insufficient tissue oxygenation, which results in impaired oxidative energy production. A reduction in cellular oxygen levels induces the stabilization of hypoxia inducible factor α (HIF-1α), master regulator of the molecular response to hypoxia, involved in maintaining cellular homeostasis and driving hypoxic adaptation through the control of gene expression. Due to its high energy requirement, the brain is particularly vulnerable to oxygen shortage. Thus, hypoxic injury can cause significant metabolic changes in neural cell populations, which are associated with neurodegeneration. Recent evidence suggests that regulating HIF-1α may ameliorate the cellular damage in neurodegenerative diseases. Indeed, the hypoxia/HIF-1α signaling pathway has been associated to several processes linked to Parkinson's disease (PD) including gene mutations, risk factors and molecular pathways such as mitochondrial dysfunction, oxidative stress and protein degradation impairment. This review will explore the impact of hypoxia and HIF-1α signaling on these specific molecular pathways that influence PD development and will evaluate different novel neuroprotective strategies involving HIF-1α stabilization.

Oxidative-Signaling in Neural Stem Cell-Mediated Plasticity: Implications for Neurodegenerative Diseases

The adult mammalian brain is capable of generating new neurons from existing neural stem cells (NSCs) in a process called adult neurogenesis. This process, which is critical for sustaining cognition and mental health in the mature brain, can be severely hampered with ageing and different neurological disorders. Recently, it is believed that the beneficial effects of NSCs in the injured brain relies not only on their potential to differentiate and integrate into the preexisting network, but also on their secreted molecules. In fact, further insight into adult NSC function is being gained, pointing to these cells as powerful endogenous "factories" that produce and secrete a large range of bioactive molecules with therapeutic properties. Beyond anti-inflammatory, neurogenic and neurotrophic effects, NSC-derived secretome has antioxidant proprieties that prevent mitochondrial dysfunction and rescue recipient cells from oxidative damage. This is particularly important in neurodegenerative contexts, where oxidative stress and mitochondrial dysfunction play a significant role. In this review, we discuss the current knowledge and the therapeutic opportunities of NSC secretome for neurodegenerative diseases with a particular focus on mitochondria and its oxidative state.

AMPA induced cognitive impairment in rats: Establishing the role of endoplasmic reticulum stress inhibitor, 4-PBA

Glutamate excitotoxicity and endoplasmic reticulum (ER) recently have been found to be instrumental in the pathogenesis of various neurodegenerative diseases. However, the paucity of literature deciphering the inter-linkage among glutamate receptors, behavioral alterations, and ER demands thorough exploration. Reckoning the aforesaid concerns, a prospective study was outlined to delineate the influence of ER stress inhibition via 4-phenylbutyric acid (PBA) on α-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) excitotoxicity-induced behavioral aspects and possible ER stress-glutamate linkage. Male SD rats were randomly divided into four groups namely sham (surgical control+vehicle, group 1), AMPA-induced excitotoxic group 2 receive a single intra-hippocampal injection of 10 mM AMPA, group 3 received AMPA along with PBA (i.p, 100 mg/kg body weight) for 15 days, and group 4 received PBA alone. Behavioral analyses were performed prior to the sacrifice of animals and hippocampus was extracted thereafter for further analysis. AMPA-induced excitotoxicity exhibited significant impairment of locomotion as well as cognitive functions. The levels of neurotransmitters such as dopamine, homo vanillic acid (HVA), norepinephrine, and serotonin were reduced accompanied by reduced expression of GLUR1 and GLUR4 (glutamate receptor) as well as loss of neurons in different layers of hippocampus. ER stress markers were upregulated upon AMPA excitotoxicity. However, chemical chaperone PBA supplementation remarkably mitigated the behavioral alterations along with expression of glutamate and ER stress intermediates/markers in AMPA excitotoxic animals. Therefore, the present exploration convincingly emphasizes the significance of ER stress and its inhibition via PBA in combating cognitive impairment as well as improving locomotion in excitotoxic animals.

Ceramide Metabolism and Parkinson's Disease-Therapeutic Targets

Ceramide is a bioactive sphingolipid involved in numerous cellular processes. In addition to being the precursor of complex sphingolipids, ceramides can act as second messengers, especially when they are generated at the plasma membrane of cells. Its metabolic dysfunction may lead to or be a consequence of an underlying disease. Recent reports on transcriptomics and electrospray ionization mass spectrometry analysis have demonstrated the variation of specific levels of sphingolipids and enzymes involved in their metabolism in different neurodegenerative diseases. In the present review, we highlight the most relevant discoveries related to ceramide and neurodegeneration, with a special focus on Parkinson's disease.

RIPK1 inhibitor ameliorates the MPP+/MPTP-induced Parkinson's disease through the ASK1/JNK signalling pathway

Receptor-interacting protein kinase 1 (RIPK1) is up-regulated in patients with neurodegenerative diseases. Our study aimed to explore the underlying mechanisms that involved in the neurotoxic function of RIPK1 in Parkinson's disease (PD). MPP+/MPTP-induced PD cellular and mice models were used in this study. The results showed that RIPK1 was high expressed and activated in MPP+-treated SH-SY5Y cells and MPTP-induced PD mice. Overexpression of RIPK1 facilitated cell apoptosis, necrosis, inflammation response, ROS production and mitochondrial dysfunction in MPP+- treated SH-SY5Y cells, while the RIPK1 inhibitor Nec-1s has an opposite effect. In addition, the Apoptosis-signaling kinase-1 (ASK1)/c-Jun N-terminal kinase (JNK) signalling pathway was activated during the overexpression of RIPK1, and inhibiting the ASK1/JNK signal by the ASK1 inhibitor partially reversed the decline of cell viability, the increase of cell apoptosis, necrosis and inflammation induced by RIPK1 overexpression in MPP+-treated SH-SY5Y cells. Further studies suggested that the inhibition of RIPK1 by Nec-1s largely alleviated the behavioural impairment in PD mice. Hence, our study indicated that the RIPK1 inhibitor Nec-1s has neuroprotective effects against PD through inactivating the ASK1/JNK signalling pathway.

Targeting S100B Protein as a Surrogate Biomarker and its Role in Various Neurological Disorders

Neurological disorders (ND) are the central nervous system (CNS) related complications originated by enhanced oxidative stress, mitochondrial failure and overexpression of proteins like S100B. S100B is a helix-loop-helix protein with the calcium-binding domain associated with various neurological disorders through activation of the MAPK pathway, increased NF-kB expression resulting in cell survival, proliferation and gene up-regulation. S100B protein plays a crucial role in Alzheimer's disease, Parkinson's disease, multiple sclerosis, Schizophrenia and epilepsy because the high expression of this protein directly targets astrocytes and promotes neuroinflammation. Under stressful conditions, S100B produces toxic effects mediated through receptor for advanced glycation end products (AGE) binding. S100B also mediates neuroprotection, minimizes microgliosis and reduces the expression of tumor necrosis factor (TNF-alpha) but that are concentration- dependent mechanisms. Increased level of S100B is useful for assessing the release of inflammatory markers, nitric oxide and excitotoxicity dependent neuronal loss. The present review summarizes the role of S100B in various neurological disorders and potential therapeutic measures to reduce the prevalence of neurological disorders.

Quantitative Proteomic Analysis of Primitive Neural Stem Cells from LRRK2 G2019S-Associated Parkinson's Disease Patient-Derived iPSCs

Parkinson's disease (PD) is a common neurodegenerative disease, causing movement defects. The incidence of PD is constantly increasing and this disease is still incurable. Thus, understanding PD pathophysiology would be pivotal for the development of PD therapy, and various PD models have thus been already developed. Through recent advances in reprogramming techniques, a primitive neural stem cell (pNSC) derived from PD patient induced pluripotent stem cells (iPSCs) could be potentially used as a reproducible and reliable experimental system to analyze the effect of the leucine-rich repeat kinase 2 G2019S mutation (LK2GS) in neural cells. Here, we investigated the advantages of such a model system through quantitative proteomic analysis of pNSCs from normal control iPSCs and familial PD patient iPSCs harboring LK2GS. We confirmed that the expression of molecules known to be involved in PD pathogenesis, such as oxidative stress-, cell adhesion-, and cytoskeleton-related proteins, were altered in the LK2GS pNSC. In addition, we showed that down-regulation of Ku80, which was found in the proteomic analysis with LK2GS pNSCs, resulted in apoptosis induced by DNA damage response. Taken together, we suggest that pNSCs from PD iPSCs could provide a reliable and useful model system to study PD. Moreover, the highly expandable pNSC is suitable for multi-omics approaches to understand PD pathologies and discover therapeutic targets for PD.

Role of Oxidative Stress and Neuroinflammation in Attention-Deficit/Hyperactivity Disorder

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder of childhood. Although abnormalities in several brain regions and disturbances of the catecholaminergic pathway have been demonstrated, the pathophysiology of ADHD is not completely understood, but as a multifactorial disorder, has been associated with an increase in oxidative stress and neuroinflammation. This review presents an overview of factors that increase oxidative stress and neuroinflammation. The imbalance between oxidants and antioxidants and also the treatment with medications are two factors that can increase oxidative damage, whereas the comorbidity between ADHD and inflammatory disorders, altered immune response, genetic and environmental associations, and polymorphisms in inflammatory-related genes can increase neuroinflammation. Evidence of an association with these factors has become valuable for research on ADHD. Such evidence opens up new intervention routes for the use of natural products as antioxidants that could have potential as a treatment against oxidative stress and neuroinflammation in ADHD.

Apoptosis, Induced by Human α-Synuclein in Yeast, Can Occur Independent of Functional Mitochondria

Human α-synuclein expression in baker’s yeast reportedly induces mitochondria-dependent apoptosis. Surprisingly, we find that, under de-repressing conditions of the inducible MET25/GAL1 promoters, yeast cells expressing chromosomally-integrated copies of the human α-synuclein gene are not killed, but spontaneously form respiration-deficient rho-minus (ρ⁻) petites. Although yeast cells can undergo cell death (apoptosis) from loss of mitochondrial function, they can also survive without functional mitochondria. Such cells are referred to as ρ⁰ or ρ⁻ petites. This study reports that minimal expression of human α-synuclein in yeast, from MET25/GAL1 promoter, gives rise to ρ⁻ petites. Interestingly, the full expression of α-synuclein, from the same promoters, in α-synuclein-triggered ρ⁻ petites and also in ρ⁰ petites (produced by treating ρ⁺ cells with the mutagen ethidium bromide) initiates apoptosis. The percentages of petites increase with increasing α-synuclein gene copy-number. ρ⁻ petites expressing α-synuclein from fully-induced MET25/GAL1 promoters exhibit increased ROS levels, loss of mitochondrial membrane potential, and nuclear DNA fragmentation, with increasing copies of α-synuclein. Our results indicate that, for the first time in yeast, α-synuclein-triggered apoptosis can occur independently of functional mitochondria. The observation that α-synuclein naturally forms petites and that they can undergo apoptosis may have important implications in understanding the pathogenesis of Parkinson’s disease.

Neuroprotective Effects of Cryptotanshinone in a Direct Reprogramming Model of Parkinson's Disease

Parkinson’s disease (PD) is a well-known age-related neurodegenerative disease. Considering the vital importance of disease modeling based on reprogramming technology, we adopted direct reprogramming to human-induced neuronal progenitor cells (hiNPCs) for in vitro assessment of potential therapeutics. In this study, we investigated the neuroprotective effects of cryptotanshinone (CTN), which has been reported to have antioxidant properties, through PD patient-derived hiNPCs (PD-iNPCs) model with induced oxidative stress and cell death by the proteasome inhibitor MG132. A cytotoxicity assay showed that CTN possesses anti-apoptotic properties in PD-hiNPCs. CTN treatment significantly reduced cellular apoptosis through mitochondrial restoration, such as the reduction in mitochondrial reactive oxygen species and increments of mitochondrial membrane potential. These effects of CTN are mediated via the nuclear factor erythroid 2-related factor 2 (NRF2) pathway in PD-hiNPCs. Consequently, CTN could be a potential antioxidant reagent for preventing disease-related pathological phenotypes of PD.

LncRNA HOTAIR promotes MPP+-induced neuronal injury in Parkinson's disease by regulating the miR-874-5p/ATG10 axis

Parkinson's disease (PD) is a neurodegenerative disease caused by the loss of dopaminergic neurons. Long non-coding RNAs (lncRNAs) play an important role in many neurological diseases, including PD. This study aimed to investigate the role of lncRNA HOX transcript antisense RNA (HOTAIR) in PD pathogenesis and its potential mechanism. SK-N-SH cells were exposed to 1-methyl-4-phenylpyridinium (MPP⁺) to mimic PD model in vitro. The levels of HOTAIR, miR-874-5p and autophagy-related 10 (ATG10) were determined by quantitative real-time polymerase chain reaction (qRT-PCR) or western blot assay. Cell viability and apoptosis were assessed by Cell Counting Kit-8 (CCK-8) assay and flow cytometry. The expression of apoptosis-related proteins was measured by western blot. The levels of neuroinflammation-related factors were detected by enzyme-linked immunosorbent assay (ELISA). Commercial kits was used to monitor lactate dehydrogenase (LDH) activity, reactive oxygen (ROS) generation and superoxide dismutase (SOD) activity. The interaction among HOTAIR, miR-874-5p and ATG10 were verified by dual-luciferase reporter assay or RNA immunoprecipitation (RIP) assay. HOTAIR and ATG10 were up-regulated, and miR-874-5p was down-regulated in dose- and time-dependent manners in MPP⁺-treated SK-N-SH cells. HOTAIR knockdown reduced MPP⁺-induced neuronal damage. HOTAIR aggrandized MPP⁺-triggered neuronal injury by sponging miR-874-5p. Also, miR-874-5p attenuated MPP⁺-triggered neuronal damage by targeting ATG10. Moreover, HOTAIR regulated ATG10 expression via sponging miR-874-5p. HOTAIR promoted MPP⁺-induced neuronal injury via modulating the miR-874-5p/ATG10 axis in SK-N-SH cells.

Control of Reactive Oxygen Species for the Prevention of Parkinson's Disease: The Possible Application of Flavonoids

Oxidative stress reflects an imbalance between the production of reactive oxygen species (ROS) and antioxidant defense systems, and it can be associated with the pathogenesis and progression of neurodegenerative diseases such as multiple sclerosis, stroke, and Parkinson's disease (PD). The application of antioxidants, which can defend against oxidative stress, is able to detoxify the reactive intermediates and prevent neurodegeneration resulting from excessive ROS production. There are many reports showing that numerous flavonoids, a large group of natural phenolic compounds, can act as antioxidants and the application of flavonoids has beneficial effects in the adult brain. For instance, it is well known that the long-term consumption of the green tea-derived flavonoids catechin and epigallocatechin gallate (EGCG) can attenuate the onset of PD. Also, flavonoids such as ampelopsin and pinocembrin can inhibit mitochondrial dysfunction and neuronal death through the regulation of gene expression of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. Additionally, it is well established that many flavonoids exhibit anti-apoptosis and anti-inflammatory effects through cellular signaling pathways, such as those involving (ERK), glycogen synthase kinase-3β (GSK-3β), and (Akt), resulting in neuroprotection. In this review article, we have described the oxidative stress involved in PD and explained the therapeutic potential of flavonoids to protect the nigrostriatal DA system, which may be useful to prevent PD.

In Vivo Cognitive-Enhancing, Ex Vivo Malondialdehyde-Lowering Activities and Phytochemical Profiles of Aqueous and Methanolic Stem Bark Extracts of Piliostigma thonningii (Schum.)

Cognitive impairment (CI) is among the leading causes of disability in humans. It is estimated that over 35.6 million people are suffering from Alzheimer's disease- (AD-) associated cognitive deficits globally with these statistics projected to rise over 115.4 million by the year 2050. There is no specific etiology for this cognitive impairment; however, various contributing factors including advancing age (>60 years old), oxidative stress, cerebral injuries, infections, neurologic disorders, and cancer have been implicated. Despite various attempts to manage CI, no curative medicines are yet available. The current drugs used to manage symptoms of AD-associated CI including Donepezil and Rivastigmine among others are only palliative rather than therapeutic. Furthermore, these agents have been associated with undesirable side effects. This calls for alternative and complementary approaches aimed at either preventing or reverting AD-related CI in a curative way without causing adverse events. It is estimated that over 80% of the world's population utilize herbal medicines for basic healthcare as it is considered safe, affordable, and easily accessible as opposed to conventional healthcare. Various parts of P. thonningii are used in traditional medicine to manage various conditions including CI. However, empirical and scientific data to validate these uses is lacking. In this study, the Morris water maze (MWM) experiment was adopted to evaluate the cognitive-enhancing effects of the studied plant extracts. The malondialdehyde (MDA) profiles in the brains of experimental mice were determined using the thiobarbituric acid reactive substances (TBARS) test. Moreover, qualitative phytochemical profiling of the studied plant extracts was performed using standard procedures. The results showed remarkable cognitive-enhancing activities which were reflected in significantly shorter transfer latencies, navigation distances, longer time spent in platform quadrant, and lower MDA levels compared with those recorded for the negative control mice (p < 0.05). Phytochemical screening of the studied plant extracts revealed the presence of antioxidant phytocompounds, which may have played key roles in the extracts' potency. Based on the findings herein, P. thonningii extracts, especially the aqueous ones have a promising potential for the management of AD-associated CI. Further studies aimed at isolating and characterizing specific active compounds for CI from P. thonningii are recommended. Additionally, specific mode(s) of action of active principles should be elucidated. Moreover, toxicity studies should be done on the studied plant extracts to ascertain their safety.

In Vitro Antioxidant Activities of the Aqueous and Methanolic Stem Bark Extracts of Piliostigma thonningii (Schum.)

Oxidative stress has been recognized as a key driver of many ailments affecting humankind. Free radicals attack biologically important biomolecules, impairing their functioning, thereby initiating and exacerbating diseases. As a comeback, antioxidant therapies have been proposed as novel approaches to ameliorating oxidative stress-associated diseases including chronic ones. Antioxidants are thought to employ multifaceted and multitargeted mechanisms that either restore oxidative homeostasis or prevent free radical buildup in the body, which overwhelm the endogenous defenses. Plants have been used for many ages across time to manage human diseases, and have a host of antioxidant phytocompounds. Piliostigma thonningii is traditionally used for the management of inflammation, malaria fever, rheumatism, and insanity, among other diseases caused by a disturbed redox state in the body. In this study, in vitro antioxidant activities of the methanolic and aqueous stem bark extracts of P. thonningii were evaluated using the in vitro antilipid peroxidation, the 1,1-diphenyl-2-picryhydrazyl (DPPH) free radical scavenging, and the ferric reducing antioxidant power assay methods. The obtained results revealed remarkable antioxidant activities of the studied plant extracts as evidenced by the low IC50 and EC50 values. These antioxidant activities could be due to the presence of antioxidant phytochemicals like flavonoids, carotenoids, tannins, and phenols, among others. Therefore, the therapeutic potency of this plant could be due to its antioxidant properties. This study recommends in vivo antioxidant efficacy testing of the studied plant extracts, as well as isolation and characterization of bioactive antioxidant compounds that are potent against oxidative stress.

Minocycline Protects against Rotenone-Induced Neurotoxicity Correlating with Upregulation of Nurr1 in a Parkinson's Disease Rat Model

The aim of this study was to investigate the effect of minocycline in rats with rotenone-induced Parkinson's disease (PD). The open field test was performed to determine the motor ability of the rats. Double immunofluorescence staining was used to detect the expression of tyrosine hydroxylase (TH) and Nurr1 in the substantia nigra (SN) of rats. The relative protein levels of TH, Nurr1, and the total- and phosphorylated-cAMP-response element binding protein (CREB) were determined by western blot analysis. The production of reactive oxygen species (ROS) and nitric oxide (NO) was detected by commercial kits. After exposure to rotenone for 28 days, rats exhibited decreased ambulation and rearing frequency and prolonged immobility time with loss of TH positive neurons in the SN. The phosphorylation levels of CREB and Nurr1 expression decreased significantly accompanied with the release of ROS and NO. Minocycline alleviated the motor deficits of rats lesioned by rotenone and elevated the expression of TH, as well as suppressing the release of ROS and NO in the SN. That was in line with the elevated phosphorylation levels of CREB and Nurr1 expression. In conclusion, our present study showed minocycline protected against neurotoxicity in a rotenone-induced rat model of PD, which was correlated with upregulation of Nurr1.

The Role of Mitochondria in Reactive Oxygen Species Generation and Its Implications for Neurodegenerative Diseases

Mitochondria are dynamic cellular organelles that consistently migrate, fuse, and divide to modulate their number, size, and shape. In addition, they produce ATP, reactive oxygen species, and also have a biological role in antioxidant activities and Ca²⁺ buffering. Mitochondria are thought to play a crucial biological role in most neurodegenerative disorders. Neurons, being high-energy-demanding cells, are closely related to the maintenance, dynamics, and functions of mitochondria. Thus, impairment of mitochondrial activities is associated with neurodegenerative diseases, pointing to the significance of mitochondrial functions in normal cell physiology. In recent years, considerable progress has been made in our knowledge of mitochondrial functions, which has raised interest in defining the involvement of mitochondrial dysfunction in neurodegenerative diseases. Here, we summarize the existing knowledge of the mitochondrial function in reactive oxygen species generation and its involvement in the development of neurodegenerative diseases.