Rotenone, paraquat, and Parkinson's disease

Neuronal regulated cell death in aging-related neurodegenerative diseases: key pathways and therapeutic potentials

Regulated cell death (such as apoptosis, necroptosis, pyroptosis, autophagy, cuproptosis, ferroptosis, disulfidptosis) involves complex signaling pathways and molecular effectors, and has been proven to be an important regulatory mechanism for regulating neuronal aging and death. However, excessive activation of regulated cell death may lead to the progression of aging-related diseases. This review summarizes recent advances in the understanding of seven forms of regulated cell death in age-related diseases. Notably, the newly identified ferroptosis and cuproptosis have been implicated in the risk of cognitive impairment and neurodegenerative diseases. These forms of cell death exacerbate disease progression by promoting inflammation, oxidative stress, and pathological protein aggregation. The review also provides an overview of key signaling pathways and crosstalk mechanisms among these regulated cell death forms, with a focus on ferroptosis, cuproptosis, and disulfidptosis. For instance, FDX1 directly induces cuproptosis by regulating copper ion valency and dihydrolipoamide S-acetyltransferase aggregation, while copper mediates glutathione peroxidase 4 degradation, enhancing ferroptosis sensitivity. Additionally, inhibiting the Xc- transport system to prevent ferroptosis can increase disulfide formation and shift the NADP + /NADPH ratio, transitioning ferroptosis to disulfidptosis. These insights help to uncover the potential connections among these novel regulated cell death forms and differentiate them from traditional regulated cell death mechanisms. In conclusion, identifying key targets and their crosstalk points among various regulated cell death pathways may aid in developing specific biomarkers to reverse the aging clock and treat age-related neurodegenerative conditions.

Neuronal effect of 0.3 % DMSO and the synergism between 0.3 % DMSO and loss function of UCH-L1 on Drosophila melanogaster model

Dimethyl sulfoxide (DMSO) is a polar aprotic solvent which is widely used in biological and medical studies and as a vehicle for pharmacological therapy. DMSO from 0.1 % to 0.5 %, particularly 0.3 % is commonly used as solvent to dissolve compounds when testing their effect on living cell, tissues including nerve cell. However, scientific data on the effects of DMSO on nervous system is limited. Here, we present our data of case study on investigation the effects of DMSO at 0.3 % concentration on nerve cell of Drosophila melanogaster model. We found that 0.3 % DMSO concentration had affected on the active zone and glutamate receptor. Notably, this study also revealed the synergistic effect of 0.3 % DMSO and loss function of dUCH (the homolog of Ubiquitin Carboxyl terminal Hydrolase -L1, UCH-L1 in D. melanogaster). This combination caused more serious abnormalities in synapse structure, particularly number of boutons on Neuromuscular Junction, NMJ. Furthermore, 0.3 % DMSO reduced the amount of ubiquitinylated protein aggregates in the indirect flight muscle of both normal and genectic defect fly model. Taken together, data in this sytudy indicated that 0.3 % DMSO caused the aberrant morphology of the synaptic structure and decreased the number of ubiquitinylated proteins in the indirect flight muscle of Drosophila. The data from the study contributed new evidence of the effects of DMSO on the nervous system. Signigicantly, this study revealed that DMSO affected on neuron cell at low concentration which widely used as pharmacological solvent.

α-Synuclein pathology and mitochondrial dysfunction: Toxic partners in Parkinson's disease

Two major neuropathological features of Parkinson's disease (PD) are α-synuclein Lewy pathology and mitochondrial dysfunction. Although both α-synuclein pathology and mitochondrial dysfunction may independently contribute to PD pathogenesis, the interaction between these two factors is not yet fully understood. In this review, we discuss the physiological functions of α-synuclein and mitochondrial homeostasis in neurons as well as the pathological defects that ensue when these functions are disturbed in PD. Recent studies have highlighted that dysfunctional mitochondria can become sequestered within Lewy bodies, and cell biology studies have suggested that α-synuclein can directly impair mitochondrial function. There are also PD cases caused by genetic or environmental perturbation of mitochondrial homeostasis. Together, these studies suggest that mitochondrial dysfunction may be a common pathway to neurodegeneration in PD, triggered by multiple insults. We review the literature surrounding the interaction between α-synuclein and mitochondria and highlight open questions in the field that may be explored to advance our understanding of PD and develop novel, disease-modifying therapies.

MEK1 inhibition ameliorates mitochondrial-dependent apoptosis induced by deltamethrin in mouse hippocampal neuron HT22 cells

Deltamethrin (DM), a widely used pyrethroid insecticide, has been increasingly recognized as a risk factor for neurodegeneration. However, the underlying mechanism is still far from clear. In this study, we investigated whether MEK1 is involved in DM-induced neurotoxicity and mediated mitochondrial-dependent apoptosis. In mouse hippocampal neuron HT22 cells model, DM (2,10,50 μM) dose-dependently increased apoptotic cells rate and impaired mitochondrial membrane potential (MMP), as well as significantly upregulated of apoptotic related proteins Bax, cytochrome c (Cyt-c) and Caspase-3 were observed. RNA-sequencing analysis further revealed that the MEK/ERK signal pathway was remarkably enriched and activated after DM exposure. In particularly, upregulation of MEK1, other than ERK1/2, was detected at both transcriptional and translational levels. Inhibition of MEK1 can effectively result in the recovery of mitochondrial morphology and MMP in DM-treated HT22 cells. And that further alleviated apoptosis by reversing the overexpression of Bax, Cyt-c and Caspase-3. Collectively, these findings demonstrate the critical role of MEK1 in regulating mitochondrial-dependent apoptosis induced by DM, providing a novel understanding of the neurotoxicity of DM.

The neurotoxicity of Paraquat and its degradation products on drosophila melanogaster

Photodegradation is a promising technique for remediating contaminated environmental matrices. It demonstrates significant potential in transforming organic contaminants into carbon dioxide, water, and inorganic anions through degradation reactions that involve transient oxidizing species, mainly hydroxyl radicals generated by ultraviolet (UV) irradiation. In this study, we investigated whether the photodegradation of Paraquat (PQ) with UV irradiation reduced its toxicity in Drosophila melanogaster. Our results indicate that ingesting PQ degradation products by larvae resulted in a low axial ratio (pupal volume). In the adults, it resulted in markedly diminished climbing ability in a time-dependent manner after 10 days of feeding. In addition, exposure of D. melanogaster to photodegradation of PQ reduced acetylcholinesterase and citrate synthase activities but improved oxidative stress, as evidenced by protein carbonyl, and lactate production. These results suggest that the photodegradation of PQ with UV irradiation produced PQ fragments with higher toxicity than PQ, while the precise mechanism of its action requires further investigation.

Introducing internal allocation factors for assessing aggregate pesticide exposure across multiple pathways and routes

In the health risk assessment of pesticides, methods for external exposure assessment have been well developed. However, quantifying the contribution of various exposure pathways or routes to internal dose remains challenging. This study introduced the internal allocation factor (IAF) for 319 pesticides to investigate the impact of different exposure pathways and routes on chemical distribution within the human body. The IAFs can be calculated from various exposure sources (or pathways), routes, and biological samples. Analysis of different exposure sources revealed that crop exposure generally had the lowest IAF in organs and tissues, indicating a high contribution to the internal dose. The median IAF values for crop exposure in blood, liver, lung, kidney, fat, and muscle were all around 1.05. For three exposure routes of soil pesticide, the results found that IAF values for oral and dermal exposure routes were significantly lower than those for inhalation exposure. When the pesticide concentrations in biological samples are known, IAF can be utilized to back-calculate the pesticide levels in other organs and tissues. The results show that under a single exposure route, the concentration factor varies greatly between organs or tissues due to differences in compositions of human tissues (e.g., water and lipid contents) and pesticide properties (e.g., hydrophilicity and lipophilicity).

The neurotoxicity of pesticides: Implications for Parkinson's disease

Parkinson's disease (PD) is the fastest-growing neurodegenerative disorder worldwide, and no effective cure is currently available. Neuropathologically, PD is characterized by the selective degeneration of dopaminergic neurons in the substantia nigra and by the accumulation of alpha-synuclein (aSyn)-rich proteinaceous inclusions within surviving neurons. As a multifactorial disorder, approximately 85 % of PD cases are sporadic with unknown etiology. Among the many risk factors implicated in PD, exposure to neurotoxic pesticides stands out as a significant contributor. While the effects of many are still uncharacterized, it has already been shown that rotenone, paraquat, maneb, and dieldrin affect critical cellular pathways, including mitochondrial and proteasomal dysfunction, aSyn aggregation, autophagy dysregulation, and disruption of dopamine metabolism. With the constant rise in pesticide usage to meet the demands of a growing human population, the risk of environmental contamination and subsequent PD development is also increasing. This review explores the molecular mechanisms by which pesticide exposure influences PD development, shedding light on their role in the pathogenesis of PD and highlighting the need for preventative measures and regulatory oversight to mitigate these risks.

ECHS1-NOX4 interaction suppresses rotenone-induced dopaminergic neurotoxicity through inhibition of mitochondrial ROS production

BACKGROUND

Parkinson's disease (PD) is the most common neurodegenerative movement disorder with uncleared mechanisms. Short-chain enoyl-CoA hydratase 1 (ECHS1) is a mitochondrial enzyme critical for the β-oxidation of fatty acids and ATP production. This study aims to explore the roles of ECHS1 in PD by using rotenone-induced experimental PD models.

METHODS

To evaluate the role of ECHS1 in rotenone-induced dopaminergic neurodegeneration, adeno-associated virus (AAV)-ECHS1 was stereotactically injected into the substantia nigra region of mice to overexpress ECHS1. Motor function of mice among groups was detected by rotarod test and gait analysis. Neurodegeneration, mitochondrial dysfunction and apoptosis were determined by immunohistochemistry, immunofluorescence staining, Western blot or kits, respectively.

RESULTS

The expression and activity of ECHS1 were decreased in PD mice and positive correlations between ECHS1 reduction and dopaminergic neurodegeneration were observed. Overexpression of ECHS1 by AAV delivery attenuated loss of dopaminergic neuron and motor deficits in PD mice. Mechanistically, ECHS1 attenuated rotenone-induced mitochondrial swelling and loss of cristae as well as decrease of ATP production, mitochondrial membrane potential, complex I/IV activities and oxygen consumption rate (OCR). Mitochondrial ROS (mtROS)-targeted antioxidant mito-TEMPO prevented ECHS1 silence-mediated mitochondrial dysfunction. Furthermore, we found that ECHS1 interacted with NADPH oxidase 4 (NOX4), resulting in decrease of NOX4 activation and subsequent reduction of mtROS production and mitochondrial dysfunction. Finally, inhibition of NOX4 by GLX351322 or mtROS production by mito-TEMPO greatly reduced ECHS1 silence-mediated apoptosis in rotenone-treated SH-SY5Y cells.

CONCLUSIONS

ECHS1 counteracted dopaminergic neurodegeneration through inhibition of mtROS and restoration of mitochondrial function via interaction with NOX4. Given the central role of mitochondrial dysfunction in PD pathogenesis, elucidating the role of ECHS1 holds great promise for uncovering novel therapeutic targets.

The relationship between serum GDF15 levels and non-motor symptoms in Parkinson's disease

OBJECTIVES

The primary aim was to investigate the relationship between serum growth differentiation factor-15 (GDF15) levels and non-motor symptom (NMS) in Parkinson's disease (PD) patients. The secondary aim was to explore the diagnostic value of GDF15 for specific NMS.

METHODS

A total of 102 PD patients were enrolled in this study, including 47 males and 55 females. Doctors collected the clinical and demographic information of patients and detected the level of serum GDF15. Next, linear univariate and multivariate linear regression analyses were used to assess the correlation between GDF15 and NMS. Receiver operating characteristic curve analysis was performed to determine the optimal cut-off value of GDF15 and evaluate its diagnostic value.

RESULTS

In PD patients, there was no significant difference in serum GDF15 levels between males and females (p = 0.831). Age of PD onset, pesticide use, depression, sexual dysfunction, Epworth Sleepiness Scale (ESS) and Hamilton Depression Scale (HAMD) were associated with serum GDF15. Serum GDF15 was negatively correlated with HAMD, depression and sexual dysfunction and positively correlated with ESS. Each 10 pg/ml increase in serum GDF15 levels was associated with a 4% lower risk of depression and a 5% lower risk of sexual dysfunction. Notably, serum GDF15 may be a biomarker for distinguishing depression and sexual dysfunction in PD patients.

CONCLUSION

Elevated serum GDF15 reduced the risk of PD with depression and sexual dysfunction. Serum GDF15 may be a biomarker for distinguishing depression and sexual dysfunction in PD patients.

Proximity to Golf Courses and Risk of Parkinson Disease

Importance

The role of pesticide exposure from golf courses in Parkinson disease (PD) risk remains unclear.

Objective

To assess whether proximity to golf courses is associated with increased PD risk and to use information on groundwater vulnerability and municipal well locations to investigate drinking water contamination as a potential route of exposure.

Design, Setting, and Participants

This case-control study included patients with incident PD and matched controls from the Rochester Epidemiology Project from 1991 to 2015. Data were analyzed between June and August 2024.

Exposures

Distance to golf courses, living in water service areas with a golf course, living in water service areas in vulnerable groundwater regions, living in water service areas with shallow municipal wells, and living in water service areas with a municipal well on a golf course.

Main Outcome and Measures

Risk of incident PD. All models adjusted for age, sex, race and ethnicity, year of index, median household income, and urban or rural category.

Results

A total of 419 incident PD cases were identified (median [IQR] age, 73 [65-80] years; 257 male [61.3%]) with 5113 matched controls (median [IQR] age, 72 [65-79] years; 3043 male [59.5%]; 4504 White [88.1%]). After adjusting for patient demographics and neighborhood characteristics, living within 1 mile of a golf course was associated with 126% increased odds of developing PD compared with individuals living more than 6 miles away from a golf course (adjusted odds ratio [aOR], 2.26; 95% CI, 1.09-4.70). Individuals living within water service areas with a golf course had nearly double the odds of PD compared with individuals in water service areas without golf courses (aOR, 1.96; 95% CI, 1.20-3.23) and 49% greater odds compared with individuals with private wells (aOR, 1.49; 95% CI, 1.05-2.13). Additionally, individuals living in water service areas with a golf course in vulnerable groundwater regions had 82% greater odds of developing PD compared with those in nonvulnerable groundwater regions (aOR, 1.82; 95% CI, 1.09-3.03).

Conclusions and Relevance

In this population-based case-control study, the greatest risk of PD was found within 1 to 3 miles of a golf course and risk generally decreased with distance. Associations with the largest effect sizes were in water service areas with a golf course and in vulnerable ground water regions.

Construction of a toxicity pathway from activation of the TLR4/NF-κB/NLRP3 axis to Parkinson's disease-like non-motor symptoms in mice

Bipyridyl herbicides, like paraquat, are among the most widely used herbicides worldwide. Although the lungs are the main target organ for acute exposure to paraquat, chronic exposure to paraquat is thought to induce neurotoxicity and is one of the environmental risk factors for neurodegenerative diseases. In the last two decades, as paraquat has been banned in some regions, diquat has gradually become its replacement. However, systematic studies of environmental factor-induced neurodegenerative diseases are incomplete, and information on threats and risk assessment is still insufficient. The aim of this study was to investigate the association between bipyridine herbicides and sporadic Parkinson's disease. Among them, we refer to the concept of Adverse Outcome Pathway (AOP), integrate, analyse and propose the toxicity pathway similar to AOP. It provides ideas for us to conduct traditional toxicological studies. As a result, the present study reveals that bipyridine herbicide exposure causes neuronal pyrocytosis in locus coeruleus through activation of the TLR4/NF-κB/NLRP3 axis, resulting in the development of Parkinson's disease-like non-motor symptoms in mice.

Mitochondrial complex I deficiency occurs in skeletal muscle of a subgroup of individuals with Parkinson's disease

BACKGROUND

Widespread neuronal mitochondrial complex I (CI) deficiency was recently reported to be a characteristic in a subgroup of individuals with idiopathic Parkinson's disease (PD). Here, we sought to determine whether a CI-deficient subgroup could be discerned using clinically accessible muscle biopsies. We further hypothesized that the inconsistency of previous findings of mitochondrial respiratory impairment in PD muscle may be due to interindividual variation, with respiratory deficiency only occurring in a subgroup of cases.

METHODS

Using a cross-sectional design, vastus lateralis needle biopsies were collected from 83 individuals with PD and 29 neurologically healthy controls and analyzed by immunohistochemistry for CI and complex IV (CIV), cytochrome c oxidase/succinate dehydrogenase (COX/SDH) histochemistry, and spectrophotometric activity assays of complexes I-IV. Mitochondrial DNA (mtDNA) copy number, deletions, and point variation were analyzed in single muscle fibers and bulk biopsy samples.

RESULTS

We show that PD muscle exhibits reduced CI activity at the group level, with 9% of cases falling below two standard deviations of the control group. In contrast, the activities of CII-CIV are not significantly different between the PD and control groups. No quantitative change of CI or CIV is detected, and the observed functional CI deficiency is not associated with mtDNA abnormalities.

CONCLUSIONS

Our findings support the existence of a PD subpopulation characterized by CI pathology in skeletal muscle and suggest that stratification by extra-neural mitochondrial dysfunction may be informative for selecting individuals for clinical trials.

Environmental exposures and familial background alter the induction of neuropathology and inflammation after SARS-CoV-2 infection

Post-infection sequela of several viruses have been linked with Parkinson's disease (PD). Here, we investigated whether mice infected with SARS-CoV-2 alone or in combination with two putative Parkinsonian toxins, MPTP and paraquat, increased the susceptibility to develop Parkinsonian pathology. We also examined if G2019S LRRK2 mice had any change in sensitivity to SARS-CoV-2 as well as if vaccination against this virus altered any neuropathology. Infection with WA-1/2020 or Omicron B1.1.529 strains sensitized both WT and G2019S LRRK2 mice to the neuropathological effects of a subtoxic exposure to MPTP, but not paraquat. These neuropathologies were rescued in WT mice vaccinated with mRNA- or protein-based SARS-CoV-2 vaccines. However, G2019S LRRK2 mutant mice were only protected with the protein-based vaccine. These results highlight the role of both environmental exposures and familial background on the development of Parkinsonian pathology secondary to viral infection and the benefit of vaccines in reducing these risks.

Mitochondrial stress disassembles nuclear architecture through proteolytic activation of PKCδ and Lamin B1 phosphorylation in neuronal cells: implications for pathogenesis of age-related neurodegenerative diseases

Mitochondrial dysfunction and oxidative stress are central to the pathogenesis of neurodegenerative diseases, including Parkinson's, Alzheimer's and Huntington's diseases. Neurons, particularly dopaminergic (DAergic) ones, are highly vulnerable to mitochondrial stress; however, the cellular and molecular mechanisms underlying this vulnerability remain poorly understood. Previously, we demonstrated that protein kinase C delta (PKCδ) is highly expressed in DAergic neurons and mediates apoptotic cell death during neurotoxic stress via caspase-3-mediated proteolytic activation. Herein, we further uncovered a key downstream molecular event of PKCδ signaling following mitochondrial dysfunction that governs neuronal cell death by dissembling nuclear architecture. Exposing N27 DAergic cells to the mitochondrial complex-1 inhibitor tebufenpyrad (Tebu) induced PKCδ phosphorylation at the T505 activation loop accompanied by caspase-3-dependent proteolytic activation. High-resolution 3D confocal microscopy revealed that proteolytically activated cleaved PKCδ translocates to the nucleus, colocalizing with Lamin B1. Electron microscopy also visualized nuclear membrane damage in Tebu-treated N27 cells. In silico analyses identified threonine site on Lamin B1 (T575) as a phosphorylation site of PKCδ. Interestingly, N27 DAergic cells stably expressing a PKCδ cleavage-resistant mutant failed to induce nuclear damage, PKCδ activation, and Lamin B1 phosphorylation. Furthermore, CRISPR/Cas9-based stable knockdown of PKCδ greatly attenuated Tebu-induced Lamin B1 phosphorylation. Also, studies using the Lamin B1T575G phosphorylation mutant and PKCδ-ΔNLS-overexpressing N27 cells showed that PKCδ activation and translocation to the nuclear membrane are essential for phosphorylating Lamin B1 at T575 to induce nuclear membrane damage during Tebu insult. Additionally, Tebu failed to induce Lamin B1 damage and Lamin B1 phosphorylation in organotypic midbrain slices cultured from PKCδ-/- mouse pups. Postmortem analyses of PD brains revealed significantly higher PKCδ activation, Lamin B1 phosphorylation, and Lamin B1 loss in nigral DAergic neurons compared to age-matched healthy controls, demonstrating the translational relevance of these findings. Collectively, our data reveal that PKCδ functions as a Lamin B1 kinase to disassemble the nuclear membrane during mitochondrial stress-induced neuronal death. This mechanistic insight may have important implications for the etiology of age-related neurodegenerative diseases resulting from mitochondrial dysfunction as well as for the development of novel treatment strategies.

Substantia nigra and blood gene signatures and biomarkers for Parkinson's disease from integrated multicenter microarray-based transcriptomic analyses

Background

Parkinson's disease (PD) is a complex, common neurodegenerative disorder with unclear etiology. The pathogenic hallmark is the death of dopaminergic neurons in the substantia nigra. PD diagnosis depends on clinical manifestation of symptoms but is lack of effective biomarker.

Methods

Available human microarray-based transcriptomic datasets of the substantia nigra and blood were acquired for PD cases and controls. Robust rank aggregation and Weighted Gene Co-expression Network analysis were performed to identify gene signatures in substantia nigra and blood of PD. An overlapping analysis and validation in an independent cohort were followed to identify PD blood biomarkers.

Results

Eight datasets of substantia nigra and 3 datasets of blood were retrieved, which comprised 150 substantia nigra and 571 blood samples. Integrated differentially expressed genes (DEG) and module analyses showed that the substantia nigra gene signature in PD comprised 170 key genes, mainly involved in dopaminergic synapse, neuroactive ligand-receptor interaction, calcium signaling pathway, and Parkinson disease. The blood gene signature had only 65 DEGs, but with no robust co-expression module identified. Two genes, LRRN3 and TUBB2A, were both downregulated in the substantia nigra and blood of PD. But only TUBB2A was validated in the blood of independent cohort and showed a capacity of PD prediction.

Conclusion

The present study identified PD-associated gene signatures of the substantia nigra and blood, and demonstrated that the reduced expression of TUBB2A in the blood is promising to predict PD. Our findings provide novel insight into the mechanisms underlying PD pathophysiology and the development of PD biomarkers.

Global, regional and national temporal trends in Parkinson's disease incidence, disability-adjusted life year rates in middle-aged and older adults: a cross-national inequality analysis and Bayesian age-period-cohort analysis based on the global burden of disease 2021

BACKGROUND

Parkinson's disease (PD) ranks as the second most prevalent neurodegenerative disorder; however, its epidemiological characteristics among middle-aged and older adults at global, regional, and national levels remain inadequately documented.

METHODS

This study assessed temporal trends in PD among middle-aged and older adults by extracting incidence rates, disability-adjusted life year (DALY) rates, and corresponding age-specific rates (ASRs) from the Global Burden of Disease (GBD) database spanning 1990 to 2021. Estimated annual percentage change (EAPC) was employed to analyze trends over the past 30 years. The slope index of inequality (SII) and concentration index (CI) were utilized to evaluate disparities in the burden of PD across various countries. Additionally, Bayesian age-period-cohort (BAPC) modeling was applied to project DALY figures for the next 15 years.

RESULTS

In 2021, the global incidence and DALY rates for middle-aged and older adults with PD stood at 79.68 and 477.50 cases per 100,000 population, respectively. Both incidence and DALY rates have exhibited an upward trajectory over the past 32 years, with EAPCs of 1.2 (95% UI: 1.1-1.3) and 0.6 (95% UI: 0.5-0.7), respectively. Among the five sociodemographic index (SDI) regions, the high-middle SDI region reported the highest incidence and DALY rates for PD in 2021, at 93.93 and 512.29 cases per 100,000 population, respectively. A positive correlation was observed between the SDI and age-specific incidence rate (ASIR) as well as age-specific DALY rate (ASDR). Disparities in the burden of PD among middle-aged and older adults, associated with SDI, are on the rise and are primarily concentrated in high SDI countries. It is projected that the global incidence and DALY rates for middle-aged and older adults with PD will experience significant increases over the next 15 years.

CONCLUSIONS

The global burden of PD among middle-aged and older adults has markedly escalated over the past 32 years, particularly in high-middle SDI regions. These findings underscore the necessity for the development of effective interventions and public health policies, contributing to the attainment of the sustainable development goals established by the World Health Organization (WHO).

Gluten and its relationship with inflammation and Parkinson's Disease: A literature review

Parkinson's Disease is a neurodegenerative central nervous system (CNS) disease that primarily affects the dopaminergic cells of the Substantia Nigra in the midbrain and causes a diverse array of symptoms, including dystonia, a loss of balance, difficulty initiating movements, akinesia, muscle spasms, and tremors. It has long been known that environmental and commercial compounds are linked to an increased risk of Parkinson's Disease. Of importance, gluten, a complex polysaccharide, has been hypothesized to cause some of the symptoms related to Parkinson's Disease. It is hypothesized that gluten causes a chronic inflammatory state which may lead to plaque formation and neuronal cell death in the substantia nigra, alongside the symptoms of Parkinson's Disease. This literature review hopes to explore the relationship gluten has as an inflammatory molecule and its role in the production and prolongation of the disease processes in Parkinson's Disease.

Rotenone induced acute miRNA alterations in extracellular vesicles produce mitochondrial dysfunction and cell death

How extracellular vesicles (EVs) may contribute to mechanisms of primary intracellular pathogenesis in Parkinson's disease (PD) remains unknown. To critically advance our understanding of how EVs influence early-stage PD pathogenesis, we tested the hypothesis that rats acutely exposed to the PD neurotoxin rotenone would produce differential miRNAs in CSF/serum-derived EVs and that such modulation would be responsible for PD-relevant functional alterations in recipient neuronal cells. We discovered that acute rotenone treatment produced significant and specific serum miRNA alterations. Primary midbrain neurons treated with serum EVs from rotenone-exposed rats produced oxidative stress, mitochondrial toxicity, and cell loss in neuronal culture. These mechanisms were dependent on miR-30a-5p and miR-484. Thus, this study has elucidated that differential expression of miRNAs in circulating EVs from serum/CSF of rats is a potential early diagnostic marker for PD, and that the modulation of cellular functions and viability due to extracellular vesicles determines the pathological fate.

Global trends and projections of Parkinson's disease incidence: a 30-year analysis using GBD 2021 data

BACKGROUND AND OBJECTIVES

Parkinson's disease (PD) is a neurodegenerative disorder marked by the progressive loss of dopaminergic neurons, leading to motor dysfunction and non-motor symptoms like cognitive decline and depression. With the aging global population, PD incidence is anticipated to rise, especially in regions with rapidly growing elderly populations. This study leverages Global Burden of Disease (GBD) 2021 data to analyze the burden of PD by region, sex, and age group, examining trends from 1992 to 2021 and projecting the future burden to 2030.

METHODS

Data from the GBD 2021 database for the years 1992-2021 were analyzed to assess age-standardized incidence rates (ASIR) and mortality of PD across socio-demographic index (SDI) regions, sex, and age groups. The Age-Period-Cohort (APC) model was used to explore temporal trends, while the Bayesian Age-Period-Cohort (BAPC) model projected future PD burden from 2022 to 2030.

RESULTS

From 1992 to 2021, global PD cases increased from 450,000 to 1.34 million, with crude incidence rates rising from 8.19 to 16.92 per 100,000 and ASIR from 11.54 to 15.63 per 100,000, indicating an annual net drift of 1.11% (95% CI 1.06%-1.17%), reflecting a growing burden driven by an aging population. All SDI regions saw a growth in PD burden, with the highest increases in middle- and high-middle-SDI regions, where male incidence was notably higher than female. Incidence rates escalated sharply in individuals aged 60 and older, peaking in those aged 85 and above. Projections suggest that by 2030, global PD cases will reach 1.93 million, with an ASIR of 27 per 100,000.

DISCUSSION

The findings highlight a sustained global increase in PD burden, particularly in middle- and high-income regions and among men. In low-SDI areas, PD burden may be underestimated due to limited healthcare access and diagnostic challenges. These results stress the urgent need for health policies focused on elderly populations, especially men, and call for effective prevention and intervention strategies to mitigate the future impact of PD.

Mitochondria-targeted nanovesicles for ursodeoxycholic acid delivery to combat neurodegeneration by ameliorating mitochondrial dysfunction

Mitochondria are pivotal in sustaining oxidative balance and metabolic activity within neurons. It is well-established that mitochondrial dysfunction constitutes a fundamental pathogenic mechanism in neurodegeneration, especially in the context of Parkinson's disease (PD), this represents a promising target for therapeutic intervention. Ursodeoxycholic acid (UDCA), a clinical drug used for liver disease, possesses antioxidant and mitochondrial repair properties. Recently, it has gained attention as a potential therapeutic option for treating various neurodegenerative diseases. However, multiple barriers, including the blood-brain barrier (BBB) and cellular/mitochondrial membranes, significantly hinder the efficient delivery of therapeutic agents to the damaged neuronal mitochondria. Macrophage-derived nanovesicles (NVs), which can traverse the BBB in response to brain inflammation signals, have demonstrated promising tools for brain drug delivery. Nevertheless, natural nanovesicles inherently lack the ability to specifically target mitochondria. Herein, artificial NVs are loaded with UDCA and then functionalized with triphenylphosphonium (TPP) molecules, denoted as UDCA-NVs-TPP. These nanovesicles specifically accumulate in damaged neuronal mitochondria, reduce oxidative stress, and enhance ATP production by 42.62%, thereby alleviating neurotoxicity induced by 1-methyl-4-phenylpyridinium (MPP+). Furthermore, UDCA-loaded NVs modified with TPP successfully cross the BBB and accumulate in the striatum of PD mice. These nanoparticles significantly improve PD symptoms, as demonstrated by a 48.56% reduction in pole climb time, a 59.09% increase in hanging ability, and the restoration of tyrosine hydroxylase levels to normal, achieving remarkable therapeutic efficacy. Our work highlights the immense potential of these potent UDCA-loaded, mitochondria-targeting nanovesicles for efficient treatment of PD and other central neurodegenerative diseases.

Toxin-Induced Animal Models of Parkinson's Disease

The debilitating motor symptoms of Parkinson's disease (PD) result primarily from the degenerative nigrostriatal dopaminergic pathway. To elucidate pathogenic mechanisms and evaluate therapeutic strategies for PD, numerous animal models have been developed. Understanding the strengths and limitations of these models can significantly impact the choice of model, experimental design, and data interpretation. Herein, we systematically review the literature over the past decade. Some models no longer serve the purpose of PD models. The primary objectives of this review are: First, to assist new investigators in navigating through available animal models and making appropriate selections based on the objective of the study. Emphasis will be placed on common toxin-induced murine models. And second, to provide an overview of basic technical requirements for assessing the nigrostriatal pathway's pathology, structure, and function.

Glutathione S-transferase: A keystone in Parkinson's disease pathogenesis and therapy

Parkinson's disease is a progressive neurodegenerative disorder that predominantly affects motor function due to the loss of dopaminergic neurons in the substantia nigra. It presents significant challenges, impacting millions worldwide with symptoms such as tremors, rigidity, bradykinesia, and postural instability, leading to decreased quality of life and increased morbidity. The pathogenesis of Parkinson's disease is multifaceted, involving complex interactions between genetic susceptibility, environmental factors, and aging, with oxidative stress playing a central role in neuronal degeneration. Glutathione S-Transferase enzymes are critical in the cellular defense mechanism against oxidative stress, catalysing the conjugation of the antioxidant glutathione to various toxic compounds, thereby facilitating their detoxification. Recent research underscores the importance of Glutathione S-Transferase in the pathophysiology of Parkinson's disease, revealing that genetic polymorphisms in Glutathione S-Transferase genes influence the risk and progression of the disease. These genetic variations can affect the enzymatic activity of Glutathione S-Transferase, thereby modulating an individual's capacity to detoxify reactive oxygen species and xenobiotics, which are implicated in Parkinson's disease neuropathological processes. Moreover, biochemical studies have elucidated the role of Glutathione S-Transferase in not only maintaining cellular redox balance but also in modulating various cellular signalling pathways, highlighting its neuroprotective potential. From a therapeutic perspective, targeting Glutathione S-Transferase pathways offers promising avenues for the development of novel treatments aimed at enhancing neuroprotection and mitigating disease progression. This review explores the evident and hypothesized roles of Glutathione S-Transferase in Parkinson's disease, providing a comprehensive overview of its importance and potential as a target for therapeutic intervention.

Aging, cellular senescence and Parkinson's disease

Parkinson's disease (PD) is the most common neurodegenerative movement disorder, affecting 1-2% of people over age 65. The risk of developing PD dramatically increases with advanced age, indicating that aging is likely a driving factor in PD neuropathogenesis. Several age-associated biological changes are also hallmarks of PD neuropathology, including mitochondrial dysfunction, oxidative stress, and neuroinflammation. Accumulation of senescent cells is an important feature of aging that contributes to age-related diseases. How age-related cellular senescence affects brain health and whether this phenomenon contributes to neuropathogenesis in PD is not yet fully understood. In this review, we highlight hallmarks of aging, including mitochondrial dysfunction, loss of proteostasis, genomic instability and telomere attrition in relation to well established PD neuropathological pathways. We then discuss the hallmarks of cellular senescence in the context of neuroscience and review studies that directly examine cellular senescence in PD. Studying senescence in PD presents challenges and holds promise for advancing our understanding of disease mechanisms, which could contribute to the development of effective disease-modifying therapeutics. Targeting senescent cells or modulating the senescence-associated secretory phenotype (SASP) in PD requires a comprehensive understanding of the complex relationship between PD pathogenesis and cellular senescence.

Oxidative Stress in Brain Function

Oxidative stress (OS) is an important factor in the pathophysiology of numerous neurodegenerative disorders, such as Parkinson's disease, multiple sclerosis, cerebrovascular pathology or Alzheimer's disease. OS also significantly influences progression among the various neurodegenerative disorders. The imbalance between the formation of reactive oxygen species (ROS) and the body's capacity to neutralize these toxic byproducts renders the brain susceptible to oxidative injury. Increased amounts of ROS can result in cellular malfunction, apoptosis and neurodegeneration. They also represent a substantial factor in mitochondrial dysfunction, a defining characteristic of neurodegenerative disorders. Comprehending the fundamental mechanisms of OS and its interactions with mitochondrial function, neuroinflammation and cellular protective pathways becomes essential for formulating targeted therapeutics to maintain brain health and reduce the impacts of neurodegeneration. We address recent highlights on the role of OS in brain function in terms of significance for neuronal health and the progression of neurodegenerative disorders.

A Nurr1 Agonist Derived from the Natural Ligand DHI Induces Neuroprotective Gene Expression

The dopamine metabolite 5,6-dihydroxyindole (DHI) has been discovered as a natural Nurr1 ligand with potential biological relevance and is an attractive lead for Nurr1 modulator development but exhibits chemical reactivity and weak potency. We have systematically explored the SAR of 5-chloroindole-6-carboxamide as a DHI mimetic scaffold and identified the first high-affinity (Kd 0.08-0.12 μM) ligands of the DHI binding site of Nurr1. An optimized Nurr1 agonist of this scaffold endowed with favorable physicochemical properties, high selectivity, and low toxicity emerges as a chemical tool to explore the biological impact of Nurr1 activation via the DHI binding site. Treatment of neuronal cells with this compound mediated enhanced expression of Nurr1-regulated neuroprotective genes like brain-derived neurotrophic factor (BDNF), supporting the great potential of Nurr1 activation in neurodegeneration.

Motor and Non-Motor Effects of Acute MPTP in Adult Zebrafish: Insights into Parkinson's Disease

Parkinson's disease (PD), the second most common neurodegenerative disorder, is characterized by the progressive loss of dopaminergic neurons in the substantia nigra pars compacta, leading to motor and non-motor symptoms. The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) has been extensively used in different animal species to develop chemical models of PD. This study aimed to evaluate the effects of acute exposure to MPTP (3 × 150 mg/kg, intraperitoneally) on adult zebrafish by assessing the neurochemical, transcriptional, and motor changes associated with PD pathogenesis. MPTP treatment resulted in a significant decrease in brain catecholamines, including dopamine, norepinephrine, and normetanephrine. Additionally, a trend towards decreased levels of dopamine precursors (tyrosine and L-DOPA) and degradation products (3-MT and DOPAC) was also observed, although these changes were not statistically significant. Gene expression analysis showed the downregulation of dbh, while the expression of other genes involved in catecholamine metabolism (th1, th2, mao, comtb) and transport (slc6a3 and slc18a2) remained unaltered, suggesting a lack of dopaminergic neuron degeneration. Behavioral assessments revealed that MPTP-exposed zebrafish exhibited reduced motor activity, consistent with the observed decrease in dopamine levels. In contrast, the kinematic parameters of sharp turning were unaffected. A significant impairment in the sensorimotor gating of the ASR was detected in the MPTP-treated fish, consistent with psychosis. Despite dopamine depletion and behavioral impairments, the absence of neurodegeneration and some hallmark PD motor symptoms suggests limitations in the validity of this model for fully recapitulating PD pathology. Further studies are needed to refine the use of MPTP in zebrafish PD models.

Mitochondrial Dysfunction in Neurodegenerative Diseases

Mitochondrial dysfunction represents a pivotal characteristic of numerous neurodegenerative disorders, including Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. These conditions, distinguished by unique clinical and pathological features, exhibit shared pathways leading to neuronal damage, all of which are closely associated with mitochondrial dysfunction. The high metabolic requirements of neurons make even minor mitochondrial deficiencies highly impactful, driving oxidative stress, energy deficits, and aberrant protein processing. Growing evidence from genetic, biochemical, and cellular investigations associates impaired electron transport chain activity and disrupted quality-control mechanisms, such as mitophagy, with the initial phases of disease progression. Furthermore, the overproduction of reactive oxygen species and persistent neuroinflammation can establish feedforward cycles that exacerbate neuronal deterioration. Recent clinical research has increasingly focused on interventions aimed at enhancing mitochondrial resilience-through antioxidants, small molecules that modulate the balance of mitochondrial fusion and fission, or gene-based therapeutic strategies. Concurrently, initiatives to identify dependable mitochondrial biomarkers seek to detect pathological changes prior to the manifestation of overt symptoms. By integrating the current body of knowledge, this review emphasizes the critical role of preserving mitochondrial homeostasis as a viable therapeutic approach. It also addresses the complexities of translating these findings into clinical practice and underscores the potential of innovative strategies designed to delay or potentially halt neurodegenerative processes.

Parkinson disease-associated toxic exposures selectively up-regulate vesicular glutamate transporter vGlut2 in a model of human cortical neurons

Parkinson disease (PD) is the second most common neurodegenerative disease, characterized by both motor and cognitive features. Motor symptoms primarily involve midbrain dopaminergic neurons, while cognitive dysfunction involves cortical neurons. Environmental factors are important contributors to PD risk. In rodents, rare midbrain dopaminergic neurons that coexpress the vesicular glutamate transporter 2 (vGlut2) are resistant to various toxins that induce dopaminergic neurodegeneration. However, it is unclear how, and with what degree of specificity, cortical glutamatergic neurons respond to PD-associated exposures with respect to vGlut2. Here, we found that vGlut2 in stem cell-derived human cortical-like glutamatergic neurons was up-regulated in a highly specific manner to certain PD-related chemicals, such as rotenone, but not others, such as paraquat. Further, exposure to recombinant preformed fibrils of alpha-synuclein (αS), a protein accumulating in PD, also increased vGlut2, while fibrils from non-PD-related proteins did not. This effect did not involve templated aggregation of endogenous αS. Finally, the knockdown of vGlut2 sensitized cortical neurons to rotenone, supporting a functional role in resilience. Thus, up-regulation of vGlut2 occurs in a highly selective manner in response to specific PD-associated exposures in a model of cortical glutamatergic neurons, a key cell type for understanding PD dementia.

A highly sensitive electrochemical sensor based on poly(3-aminobenzoic acid)/graphene oxide-gold nanoparticles modified screen printed carbon electrode for paraquat detection

Herein, a modified screen printed carbon electrode (SPCE) based on a composite material, graphene oxide-gold nanoparticles (GO-AuNPs), and poly(3-aminobenzoic acid)(P3ABA) for the detection of paraquat (PQ) is introduced. The modified electrode was fabricated by drop casting of the GO-AuNPs, followed by electropolymerization of 3-aminobenzoic acid to achieve SPCE/GO-AuNPs/P3ABA. The morphology and microstructural characteristics of the modified electrodes were revealed by scanning electron microscopy (SEM) for each step of modification. The composite GO-AuNPs can provide high surface area and enhance electroconductivity of the electrode. In addition, the presence of negatively charged P3ABA notably improved PQ adsorption and electron transfer rate, which stimulate redox reaction on the modified electrode, thus improving the sensitivity of PQ analysis. The SPCE/GO-AuNPs/P3ABA offered a wide linear range of PQ determination (10-9-10-4 mol/L) and low limit of detection (LOD) of 0.45 × 10-9 mol/L or 0.116 µg/L, which is far below international safety regulations. The modified electrode showed minimum interference effect with percent recovery ranging from 96.5% to 116.1% after addition of other herbicides, pesticides, metal ions, and additives. The stability of the SPCE/GO-AuNPs/P3ABA was evaluated, and the results indicated negligible changes in the detection signal over 9 weeks. Moreover, this modified electrode was successfully implemented for PQ analysis in both natural and tapped water with high accuracy.

Environmental Risk Factors for Parkinson's Disease: A Critical Review and Policy Implications

The age-standardized prevalence of Parkinson's disease (PD) has increased substantially over the years and is expected to increase further. This emphasizes the need to identify modifiable risk factors of PD, which could form a logical entry point for the prevention of PD. The World Health Organization (WHO) has recommended reducing exposure to specific environmental factors that have been reported to be associated with PD, in particular pesticides, trichloroethylene (TCE), and air pollution. In this review we critically evaluate the epidemiological and biological evidence on the associations of these factors with PD and review evidence on whether these putative associations are causal. We conclude that when considered in isolation, it is difficult to determine whether these associations are causal, in large part because of the decades-long lag between relevant exposures and the incidence of manifest PD. However, when considered in tandem with evidence from complementary research lines (such as animal models), it is increasingly likely that these associations reflect harmful causal effects. Fundamentally, whilst we highlight some evidence gaps that require further attention, we believe the current evidence base is sufficiently strong enough to support our call for stronger policy action. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Metallothionein II treatment mitigates rotenone-induced neurodegeneration in zebrafish models of Parkinson's disease

Introduction

Parkinson's disease (PD) is a common neurodegenerative disorder primarily affecting motor function due to progressive loss of dopaminergic neurons in the substantia nigra. Current therapies offer symptomatic relief but fail to halt disease progression, highlighting the need for novel therapeutic strategies. This study explores the neuroprotective potential of exogenous human metallothionein 2 (hMT2) peptide in a rotenone-induced PD zebrafish model.

Methods

Adult zebrafish were divided into four groups: control, rotenone-treated, hMT2 pre-treatment, and hMT2 co-treatment. PD model was established by exposing zebrafish to 5 µg/L rotenone water for 28 days. hMT2 (0.2 µg) was administered intracranially either one day before or seven days after rotenone exposure.

Results

The novel tank test demonstrated that rotenone exposure significantly impaired locomotor activity (p < 0.05) and increased anxiety-like behavior (p < 0.001). Additionally, PD model zebrafish exhibited reduced dopamine levels, decreased dopaminergic neuron population, elevated oxidative stress, heightened inflammatory response and mitochondrial dysfunction. Treatment with hMT2, especially in the co-treatment group, ameliorated these deficits by restoring locomotor activity, dopamine levels, and dopaminergic neuron counts while reducing oxidative stress and inflammation, and improving mitochondrial function.

Discussion

These results suggest that hMT2 exhibited neuroprotective effect in the PD model zebrafish. These findings support the potential of MT as a therapeutic agent for PD.

Nanotechnology in Parkinson's Disease: overcoming drug delivery challenges and enhancing therapeutic outcomes

The global prevalence of Parkinson's Disease (PD) is on the rise, driven by an ageing population and ongoing environmental conditions. To gain a better understanding of PD pathogenesis, it is essential to consider its relationship with the ageing process, as ageing stands out as the most significant risk factor for this neurodegenerative condition. PD risk factors encompass genetic predisposition, exposure to environmental toxins, and lifestyle influences, collectively increasing the chance of PD development. Moreover, early and precise PD diagnosis remains elusive, relying on clinical assessments, neuroimaging techniques, and emerging biomarkers. Conventional management of PD involves dopaminergic medications and surgical interventions, but these treatments often become less effective over time and do not address disease treatment. Challenges persist due to the blood-brain barrier's (BBB) impermeability, hindering drug delivery. Recent advancements in nanotechnology offer promising novel approaches for PD management. Various drug delivery systems (DDS), including nanosized polymers, lipid-based carriers, and nanoparticles (such as metal/metal oxide, protein, and carbonaceous particles), aim to enhance drug and gene delivery. These modifications seek to improve BBB permeability, ultimately benefiting PD patients. This review underscores the critical role of ageing in PD development and explores how age-related neuronal decline contributes to substantia nigra loss and PD manifestation in susceptible individuals. The review also highlights the advancements and ongoing challenges in nanotechnology-based therapies for PD.

The Protective Effect of Docosahexaenoic Acid on Mitochondria in SH-SY5Y Model of Rotenone-Induced Toxicity

Background: Polyunsaturated fatty acids in particular omega-3 fatty acids, such as docosahexaenoic acid (DHA), are essential nutrients and components of the plasma membrane. They are involved in various processes, including synaptic development, functionality, integrity, and plasticity, and are therefore thought to have general neuroprotective properties. Considerable research evidence further supports the beneficial effects of omega-3 fatty acids, specifically on mitochondria, through their antioxidant and anti-apoptotic properties, making them an attractive addition in treatment options for neurodegenerative disorders in which mitochondrial alterations are commonly observed. However, precise information on the underlying protective mechanisms is still lacking. Methods: We utilized the most common neuronal cell line (SH-SY5Y) and induced mitochondrial oxidative stress through the addition of rotenone. To study the potential protective effect of DHA, the cells were additionally pre-treated with DHA prior to rotenone administration. By combining SILAC labeling, mitochondria enrichment, and subsequent proteomic analyses, we aimed to determine the capacity of DHA to alleviate mitochondrial oxidative stress in vitro and further shed light on the molecular mechanisms contributing to the proposed neuroprotective effect. Results: We confirmed a reduced cell viability and an increased abundance of reactive oxygen species upon rotenone treatment, DHA pre-treatment was shown to decrease said species. Additionally proteomic analysis revealed an increased expression of mitochondrial proteins in DHA pre-treated cells. Conclusions: With our study, we were able to define a potential compensatory mechanism by which the inhibition of complex I is overcome by an increased activity of the fatty acid beta oxidation in response to DHA.

Investigating Parkinson's disease risk across farming activities using data mining and large-scale administrative health data

The risk of Parkinson's disease (PD) associated with farming has received considerable attention, in particular for pesticide exposure. However, data on PD risk associated with specific farming activities is lacking. We aimed to explore whether specific farming activities exhibited a higher risk of PD than others among the entire French farm manager (FM) population. A secondary analysis of real-world administrative insurance claim data and electronic health/medical records (TRACTOR project) was conducted to estimate PD risk for 26 farming activities using data mining. PD cases were identified through chronic disease declarations and antiparkinsonian drug claims. There were 8845 PD cases among 1,088,561 FMs. The highest-risk group included FMs engaged in pig farming, cattle farming, truck farming, fruit arboriculture, and crop farming, with mean hazard ratios (HRs) ranging from 1.22 to 1.67. The lowest-risk group included all activities involving horses and small animals, as well as gardening, landscaping and reforestation companies (mean HRs: 0.48-0.81). Our findings represent a preliminary work that suggests the potential involvement of occupational risk factors related to farming in PD onset and development. Future research focusing on farmers engaged in high-risk farming activities will allow to uncover potential occupational factors by better characterizing the farming exposome, which could improve PD surveillance among farmers.

Modeling of Parkinson's Disease in Different Models

Parkinson's Disease (PD) is a progressive disorder worldwide and its etiology remains unidentified. Over the last few decades, animal models of PD have been extensively utilized to explore the development and mechanisms of this neurodegenerative condition. Toxic and transgenic animal models for PD possess unique characteristics and constraints, necessitating careful consideration when selecting the appropriate model for research purposes. Animal models have played a significant role in uncovering the causes and development of PD, including its cellular and molecular processes. These models suggest that the disorder arises from intricate interplays between genetic predispositions and environmental influences. Every model possesses its unique set of strengths and weaknesses. This review provides a critical examination of animal models for PD and compares them with the features observed in the human manifestation of the disease.

Study on the mechanism of brain injury caused by acute diquat poisoning based on metabolomics

Brain injury following acute diquat poisoning has become increasingly common in moderate to severe cases, with unclear pathogenesis and high mortality. To investigate this, we conducted metabolomics on brain tissue from poisoned rats, combined with clinical biochemical and pathological analyses. In the high-dose group, 24 metabolites showed significant differences compared to the control group: 18 were upregulated, including cytosine, sedoheptulose-7-phosphate, indole, 3-dehydroshikimate, etc.; 6 were downregulated, including 6-phosphogluconic acid, 3-hydroxybenzoic acid, dAMP, etc. In the low-dose group, 10 metabolites showed significant differences: 4 were upregulated, including pentamidine, γ-tocotrienol, benzoylecgonine, etc.; and 6 were downregulated, including dAMP, glutathione, 3-hydroxybenzoic acid, etc. Enrichment analysis identified two key pathways-phenylalanine, tyrosine, and tryptophan biosynthesis, and the pentose phosphate pathway-as involved in brain injury. ROC analysis of six differential metabolites showed that sedoheptulose-7-phosphate, (2R)-2-hydroxy-3-(phosphonatooxy)propanoate, and 3-hydroxybenzoic acid had AUC values above 0.8. These findings suggest that these three metabolites demonstrate strong diagnostic potential for brain injury induced by diquat poisoning. Correlation analysis linked these biomarkers to clinical indicators such as neutrophil count and the eutrophil to lymphocyte ratio, supporting their relevance. This study provides insights into the mechanisms and biomarkers of diquat-induced brain injury, offering a foundation for future treatment and rapid detection.

Pyroptosis mediated by Parkin-NLRP3 negative feedback loop contributed to Parkinson's disease induced by rotenone

Rotenone remains an efficient pesticide used extensively in agriculture, leading to neurotoxicity and the increase of the prevalence of Parkinson's disease (PD). Previous studies indicated that Parkin, a neurohomeostasis regulatory factor, and NOD-like receptor protein 3 (NLRP3), a core factor driving the inflammatory response, interacted with each other, which affected neuroinflammation occurrence. However, whether rotenone accelerated PD progression via Parkin-NLRP3 loop and the specific mechanisms were still unclear. Here, a novel negative feedback mechanism of Parkin-NLRP3 that regulated PD caused by rotenone was certified. Rotenone treatment induced neurodegeneration in vitro- and vivo-models. The activation of NLRP3 inflammasome and Parkin was increased and decreased, respectively, and the expression of pyroptosis related proteins was up-regulated, because of the addition of rotenone. Notably, the overexpression of Parkin promoted NLRP3 ubiquitination, which down regulated pyroptosis mediated by NLRP3, protected mitochondrial function as well as preventing neurodegeneration. Additionally, the NLRP3 inhibitor MCC950 restored the activation of Parkin and down regulated pyroptosis mediated by NLRP3 in rotenone-induced PD. It was revealed that the Parkin-NLRP3 negative feedback loop participated in rotenone-induced PD by regulating pyroptosis, representing a new idea for the prevention and treatment of neurodegenerative diseases.

The role of the gut microbiota and the nicotinate/nicotinamide pathway in rotenone-induced neurotoxicity

Rotenone is a natural compound from plants. It is widely used in pesticides because of highly toxic to insects and fish. However, lots of research has reported that rotenone has neurotoxic effects in humans. It is confirmed there is a correlation between rotenone exposure and Parkinson's disease (PD). Therefore, the role of gut microbiota and related metabolic pathways was investigated in rotenone-induced neurotoxicity. The results showed that the abundance of gut microbiota changed significantly. The differential metabolites were enriched in the nicotinate and nicotinamide metabolism pathways, which had the greatest impact on the entire metabolic system. The contents of acetic acid and butyric acid in intestinal tissues decreased significantly. Additionally, Interleukin-6 (IL-6), Tumor necrosis factor alpha (TNF-α) and vasoactive intestinal peptide (VIP) were significantly up-regulated, while gastrin (GAS) and Ghrelin were significantly down-regulated. Expression of intestinal tight junction protein was significantly reduced. Moreover, nicotinamide adenine dinucleotide (NAD+), a the product of the nicotinate/nicotinamide pathways, decreased significantly. And the expression levels of nicotinamide phosphoribosyl transferase (NAMPT) and Solute Carrier Family 25 Member 51 (SLC25A51) also reduced significantly. Therefore, gut microbiota was influenced obviously in rats exposed to rotenone, leading to a decrease of acetic acid and butyric acid contents, which might in turn affect the change of intestinal barrier permeability and induce inflammatory reactions. Meanwhile, the nicotinate/nicotinamide metabolic pathways might play an important role in rats exposed to rotenone.

Rotenone exposure causes features of Parkinson`s disease pathology linked with muscle atrophy in developing zebrafish embryo

Parkinson's disease (PD) is associated with both genetic and environmental factors; however, sporadic forms of PD account for > 90 % of cases, and PD prevalence has doubled in the past 25 years. Depending on the importance of the environmental factors, various neurotoxins are used to induce PD both in vivo and in vitro. Unlike other neurodegenerative diseases, PD can be induced in vivo using specific neurotoxic chemicals. However, no chemically induced PD model is available because of the sporadic nature of PD. Rotenone is a pesticide that accelerates the induction of PD and exhibits the highest toxicity in fish, unlike other pesticides. Therefore, in this study, we aimed to establish a model exhibiting PD pathologies such as dysfunction of DArgic neuron, aggregation of ɑ-synuclein, and behavioral abnormalities, which are known features of PD pathology, by rotenone exposure at an environmentally relevant concentration (30 nM) in developing zebrafish embryos. Our results provide direct evidence for the association between PD and muscle degeneration by confirming rotenone-induced muscle atrophy. Therefore, we conclude that the rotenone-induced model presents non-motor and motor defects with extensive studies related to muscle atrophy.

Environmental exposures and familial background alter the induction of neuropathology and inflammation after SARS-CoV-2 infection

Basal ganglia disease has been reported as a post-infection sequela of several viruses, with documentation of this phenomenon from the H1N1 Spanish flu to the recent COVID-19 (SARS-CoV-2) pandemic. SARS-CoV-2 infection leads to multisystem deficits, including those affecting the nervous system. Here, we investigated whether a SARS-CoV-2 infection alone increases the susceptibility to develop parkinsonian phenotypes in C57BL/6J mice expressing the human ACE2 receptor, or in addition to two well-known toxin exposures, MPTP and paraquat. Additionally, we examined mice carrying a G2019S mutation in the LRRK2 gene. We also examined if vaccination with either an mRNA- or protein-based vaccine can alter any observed neuropathology. We find that the infection with the WA-1/2020 (alpha) or omicron B1.1.529 strains in ACE2 and G2019S LRRK2 mice both synergize with a subtoxic exposure to the mitochondrial toxin MPTP to induce neurodegeneration and neuroinflammation in the substantia nigra. This synergy appears toxin-dependent since we do not observe this following exposure to the direct redox-inducing compound paraquat. This synergistic neurodegeneration and neuroinflammation is rescued in WT mice that were vaccinated using either mRNA- and protein- based vaccines directed against the Spike protein of the SARS-CoV-2 virus. However, in the G2019S LRRK2 mutant mice, we find that only the protein-based vaccine but not the mRNA- based vaccine resulted in a rescue of the SARS-CoV-2 mediated neuropathology. Taken together, our results highlight the role of both environmental exposures and familial background on the development of parkinsonian pathology secondary to viral infection and the benefit of vaccines in reducing these risks.

Environmental and occupational exposure to organochlorine pesticides associated with Parkinson's disease risk: A systematic review and meta-analysis based on epidemiological evidence

OBJECTIVES

The purpose of this study was to analyze the association between environmental and occupational organochlorine pesticides (OCPs) exposure and Parkinson's disease (PD) risk.

STUDY DESIGN

Systematic review and meta-analysis.

METHODS

A comprehensive search of articles before March 18, 2024, was conducted through PubMed, Cochrane, Embase, Medlin and Web of Science databases, and the relevant data were expressed as odds ratios (OR) and 95 % confidence intervals (CI). Newcastle-Ottawa Scale (NOS) was used to evaluate literature quality. STATA (Version 11.0) was used for analysis.

RESULTS

This meta-analysis included 17 case-control studies. The results showed that OCPs exposure increased PD risk, including seven blood sample assessment exposure (BOCPs) studies (OR = 1.54, 95 % CI = 1.32-1.79) and 10 indirect assessment exposure (IOCPs) studies (OR = 1.19, 95 % CI = 1.04-1.35). Location subgroup analysis showed that OCPs was positively associated with PD risk in Asia, while there was no statistical significance in North America and Europe. The IOCPs functional subclasses subgroup results suggested that organochlorine insecticides were significantly associated with PD risk (OR = 1.18, 95%CI = 1.03-1.37). Study time may be a factor of high heterogeneity in BOCPs. In addition, BOCPs (OR = 1.49, 95%CI = 1.28-1.74) and IOCPs (OR = 1.10, 95%CI = 0.95-1.26) showed different results with PD risk.

CONCLUSIONS

Study suggests that OCPs exposure may be a risk factor for PD, but there may be location and OCPs type differences.

The role of sirtuin 1 in ageing and neurodegenerative disease: A molecular perspective

Sirtuin 1 (SIRT1), an NAD+-dependent deacetylase, has emerged as a key regulator of cellular processes linked to ageing and neurodegeneration. SIRT1 modulates various signalling pathways, including those involved in autophagy, oxidative stress, and mitochondrial function, which are critical in the pathogenesis of neurodegenerative diseases. This review explores the therapeutic potential of SIRT1 in several neurodegenerative disorders, including Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and Amyotrophic Lateral Sclerosis (ALS). Preclinical studies have demonstrated that SIRT1 activators, such as resveratrol, SRT1720, and SRT2104, can alleviate disease symptoms by reducing oxidative stress, enhancing autophagic flux, and promoting neuronal survival. Ongoing clinical trials are evaluating the efficacy of these SIRT1 activators, providing hope for future therapeutic strategies targeting SIRT1 in neurodegenerative diseases. This review explores the role of SIRT1 in ageing and neurodegenerative diseases, with a particular focus on its molecular mechanisms, therapeutic potential, and clinical applications.

Ferulic acid mitigated rotenone toxicity -Evoked Parkinson in rat model by featuring apoptosis, oxidative stress, and neuroinflammation signaling

Over time, Parkinson disease (PD) develops as a neurological illness. The goal of this study was to see whether ferulic acid has any neuroprotective benefits on the cerebellum of rats that have Parkinson's disease brought on by rotenone poisoning. A total of twenty-four male albino rats, in good condition, weighed between 200 and 250 g and nine to ten weeks old, were employed in the investigation. The control group received 1 ml of sunflower oil intraperitoneally (i.p.) each day. Rats' motor performance was considerably worse when given rotenone than it was in the control group. Rats given Ferulic Acid (FA) showed a substantial drop in the amount of glutathione (GSH) in the cerebellum. Moreover, the injection of FA resulted in a significant reduction in the optical density (OD) of the immune-positive reaction for α-synuclein, and the area percentage of BCL-2 and NF-kB immunological positive response. FA therapy, surprisingly, enhanced the OD of TH immunopositive response and apoptotic regulators (BCL2) in the cerebellum. Furthermore, FA boosted BCL2 expression, confirming the antiapoptotic effects of FA. Based on these results, FA is probably a good candidate to treat neurodegenerative diseases brought on by long-term exposure to rotenone.

Nuclear pore and nucleocytoplasmic transport impairment in oxidative stress-induced neurodegeneration: relevance to molecular mechanisms in Pathogenesis of Parkinson's and other related neurodegenerative diseases

Nuclear pore complexes (NPCs) are embedded in the nuclear envelope and facilitate the exchange of macromolecules between the nucleus and cytoplasm in eukaryotic cells. The dysfunction of the NPC and nuclear transport plays a significant role in aging and the pathogenesis of various neurodegenerative diseases. Common features among these neurodegenerative diseases, including Parkinson's disease (PD), encompass mitochondrial dysfunction, oxidative stress and the accumulation of insoluble protein aggregates in specific brain regions. The susceptibility of dopaminergic neurons to mitochondrial stress underscores the pivotal role of mitochondria in PD progression. Disruptions in mitochondrial-nuclear communication are exacerbated by aging and α-synuclein-induced oxidative stress in PD. The precise mechanisms underlying mitochondrial impairment-induced neurodegeneration in PD are still unclear. Evidence suggests that perturbations in dopaminergic neuronal nuclei are linked to PD-related neurodegeneration. These perturbations involve structural damage to the nuclear envelope and mislocalization of pivotal transcription factors, potentially driven by oxidative stress or α-synuclein pathology. The presence of protein aggregates, pathogenic mutations, and ongoing oxidative stress can exacerbate the dysfunction of NPCs, yet this mechanism remains understudied in the context of oxidative stress-induced PD. This review summarizes the link between mitochondrial dysfunction and dopaminergic neurodegeneration and outlines the current evidence for nuclear envelope and nuclear transport abnormalities in PD, particularly in oxidative stress. We highlight the potential role of nuclear pore and nucleocytoplasmic transport dysfunction in PD and stress the importance of systematically investigating NPC components in PD.

Human-Induced Pluripotent Stem Cell-Derived Neural Organoids as a Novel In Vitro Platform for Developmental Neurotoxicity Assessment

There has been a recent drive to replace in vivo studies with in vitro studies in the field of toxicity testing. Therefore, instead of conventional animal or planar cell culture models, there is an urgent need for in vitro systems whose conditions can be strictly controlled, including cell-cell interactions and sensitivity to low doses of chemicals. Neural organoids generated from human-induced pluripotent stem cells (iPSCs) are a promising in vitro platform for modeling human brain development. In this study, we developed a new tool based on various iPSCs to study and predict chemical-induced toxicity in humans. The model displayed several neurodevelopmental features and showed good reproducibility, comparable to that of previously published models. The results revealed that basic fibroblast growth factor plays a key role in the formation of the embryoid body, as well as complex neural networks and higher-order structures such as layered stacking. Using organoid models, pesticide toxicities were assessed. Cells treated with low concentrations of rotenone underwent apoptosis to a greater extent than those treated with high concentrations of rotenone. Morphological changes associated with the development of neural progenitor cells were observed after exposure to low doses of chlorpyrifos. These findings suggest that the neuronal organoids developed in this study mimic the developmental processes occurring in the brain and nerves and are a useful tool for evaluating drug efficacy, safety, and toxicity.

14-3-3 phosphorylation inhibits 14-3-3θ's ability to regulate LRRK2 kinase activity and toxicity

LRRK2 mutations are among the most common genetic causes for Parkinson's disease (PD), and toxicity is associated with increased kinase activity. 14-3-3 proteins are key interactors that regulate LRRK2 kinase activity. Phosphorylation of the 14-3-3θ isoform at S232 is dramatically increased in human PD brains. Here we investigate the impact of 14-3-3θ phosphorylation on its ability to regulate LRRK2 kinase activity. Both wildtype and the non-phosphorylatable S232A 14-3-3θ mutant reduced the kinase activity of wildtype and G2019S LRRK2, whereas the phosphomimetic S232D 14-3-3θ mutant had minimal effects on LRRK2 kinase activity, as determined by measuring autophosphorylation at S1292 and T1503 and Rab10 phosphorylation. However, wildtype and both 14-3-3θ mutants similarly reduced the kinase activity of the R1441G LRRK2 mutant. 14-3-3θ phosphorylation did not promote global dissociation with LRRK2, as determined by co-immunoprecipitation and proximal ligation assays. 14-3-3s interact with LRRK2 at several phosphorylated serine/threonine sites, including T2524 in the C-terminal helix, which can fold back to regulate the kinase domain. Interaction between 14-3-3θ and phosphorylated T2524 LRRK2 was important for 14-3-3θ's ability to regulate kinase activity, as wildtype and S232A 14-3-3θ failed to reduce the kinase activity of G2019S/T2524A LRRK2. Finally, we found that the S232D mutation failed to protect against G2019S LRRK2-induced neurite shortening in primary cultures, while the S232A mutation was protective. We conclude that 14-3-3θ phosphorylation destabilizes the interaction of 14-3-3θ with LRRK2 at T2524, which consequently promotes LRRK2 kinase activity and toxicity.

Genetically encoded fluorescent reporter for polyamines

Polyamines are abundant and evolutionarily conserved metabolites that are essential for life. Dietary polyamine supplementation extends life-span and health-span. Dysregulation of polyamine homeostasis is linked to Parkinson's disease and cancer, driving interest in therapeutically targeting this pathway. However, measuring cellular polyamine levels, which vary across cell types and states, remains challenging. We introduce a first-in-class genetically encoded polyamine reporter for real-time measurement of polyamine concentrations in single living cells. This reporter utilizes the polyamine-responsive ribosomal frameshift motif from the OAZ1 gene. We demonstrate broad applicability of this approach and reveal dynamic changes in polyamine levels in response to genetic and pharmacological perturbations. Using this reporter, we conducted a genome-wide CRISPR screen and uncovered an unexpected link between mitochondrial respiration and polyamine import, which are both risk factors for Parkinson's disease. By offering a new lens to examine polyamine biology, this reporter may advance our understanding of these ubiquitous metabolites and accelerate therapy development.

INTERSPECIES ORGANOIDS REVEAL HUMAN-SPECIFIC MOLECULAR FEATURES OF DOPAMINERGIC NEURON DEVELOPMENT AND VULNERABILITY

The disproportionate expansion of telencephalic structures during human evolution involved tradeoffs that imposed greater connectivity and metabolic demands on midbrain dopaminergic neurons. Despite the central role of dopaminergic neurons in human-enriched disorders, molecular specializations associated with human-specific features and vulnerabilities of the dopaminergic system remain unexplored. Here, we establish a phylogeny-in-a-dish approach to examine gene regulatory evolution by differentiating pools of human, chimpanzee, orangutan, and macaque pluripotent stem cells into ventral midbrain organoids capable of forming long-range projections, spontaneous activity, and dopamine release. We identify human-specific gene expression changes related to axonal transport of mitochondria and reactive oxygen species buffering and candidate cis- and trans-regulatory mechanisms underlying gene expression divergence. Our findings are consistent with a model of evolved neuroprotection in response to tradeoffs related to brain expansion and could contribute to the discovery of therapeutic targets and strategies for treating disorders involving the dopaminergic system.

The Role of Microglia and Astrocytes in the Pathomechanism of Neuroinflammation in Parkinson's Disease-Focus on Alpha-Synuclein

Glial cells, including astrocytes and microglia, are pivotal in maintaining central nervous system (CNS) homeostasis and responding to pathological insults. This review elucidates the complex immunomodulatory functions of glial cells, with a particular focus on their involvement in inflammation cascades initiated by the accumulation of alpha-synuclein (α-syn), a hallmark of Parkinson's disease (PD). Deriving insights from studies on both sporadic and familial forms of PD, as well as animal models of PD, we explore how glial cells contribute to the progression of inflammation triggered by α-syn aggregation. Additionally, we analyze the interplay between glial cells and the blood-brain barrier (BBB), highlighting the role of these cells in maintaining BBB integrity and permeability in the context of PD pathology. Furthermore, we delve into the potential activation of repair and neuroprotective mechanisms mediated by glial cells amidst α-syn-induced neuroinflammation. By integrating information on sporadic and familial PD, as well as BBB dynamics, this review aims to deepen our understanding of the multifaceted interactions between glial cells, α-syn pathology, and CNS inflammation, thereby offering valuable insights into therapeutic strategies for PD and related neurodegenerative disorders.

Disease Burden of Parkinson's Disease in Asia and Its 34 Countries and Territories from 1990 to 2021: Findings from the Global Burden of Disease Study 2021

INTRODUCTION

The increasing global population and aging have made Parkinson's disease (PD) a significant public health concern. Comprehensive evaluations of PD burden trends in Asian subregions and countries are lacking. This study investigated PD burden in Asia from 1990 to 2021, categorized by age, sex, and region.

METHODS

Data from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2021 were analyzed to assess the incidence, prevalence, mortality, and disability-adjusted life years (DALYs) across five Asian subregions and 34 countries/territories, using joinpoint regression, decomposition analysis, frontier analysis, and Bayesian models to examine changes, influencing factors, and predict future trends.

RESULTS

In 2021, the age-standardized PD incidence and prevalence in Asia were higher than the global average, particularly in East Asia (24.16 and 243.46/100,000, respectively). From 1990 to 2021, the incidence of PD in Asia rose by 198.01%, its prevalence rose by 284.35%, mortality rose by 111.27%, and DALY rose by 144.45%. Males consistently presented a greater PD burden than females did, with a growing sex gap over time. PD burden increased with age, especially among those aged 65 years and older. Population aging was the primary driver of new PD cases, and increasing etiological factors led to more patients. Inequalities in the PD burden have increased between high- and low-income areas, with low-income regions being more affected. By 2036, PD incidence is projected to increase in all subregions except the high-income Asia-Pacific region, with males experiencing a higher rate of increase.

CONCLUSION

The PD burden in Asia has significantly increased over the past three decades, particularly in middle-aged and elderly males, middle- and low-SDI countries, and individuals already suffering from PD. The increasing incidence and aging population necessitate the reallocation of medical resources, improved chronic disease management systems, stronger public health interventions, and sustainable development efforts. Research into etiological factors, pathogenesis, early diagnosis, preventive interventions, and regional management is critical.