Mitochondrial dysfunction and oxidative stress in Parkinson's disease

Role of iron in brain development, aging, and neurodegenerative diseases

It is now understood that iron crosses the blood-brain barrier via a complex metabolic regulatory network and participates in diverse critical biological processes within the central nervous system, including oxygen transport, energy metabolism, and the synthesis and catabolism of myelin and neurotransmitters. During brain development, iron is distributed throughout the brain, playing a pivotal role in key processes such as neuronal development, myelination, and neurotransmitter synthesis. In physiological aging, iron can selectively accumulate in specific brain regions, impacting cognitive function and leading to intracellular redox imbalance, mitochondrial dysfunction, and lipid peroxidation, thereby accelerating aging and associated pathologies. Furthermore, brain iron accumulation may be a primary contributor to neurodegenerative diseases such as Alzheimer's and Parkinson's diseases. Comprehending the role of iron in brain development, aging, and neurodegenerative diseases, utilizing iron-sensitive Magnetic Resonance Imaging (MRI) technology for timely detection or prediction of abnormal neurological states, and implementing appropriate interventions may be instrumental in preserving normal central nervous system function.

In situ dual-activated NIRF/PA carrier-free nanoprobe for diagnosis and treatment of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease threatening the life of millions people worldwide. Oxidative stress, mitochondrial dysfunction, and neuroinflammation are the pivotal causative elements of PD. Precise diagnosis enables timely monitoring initiation and progression of PD, thereby facilitating the formulation of customized and targeted treatment strategies. Optical imaging offers one alternative way for PD diagnosis. However, available diagnostic probes suffer from the inability to bypass the blood brain barrier (BBB). To accurately diagnose and effectively combat PD, there is an urgent need to develop an integrated diagnostic and therapeutic nanoprobe that can bypass the BBB and target the factors underlying degeneration of dopaminergic (DA) neurons. In present study, one integrated carrier-free nanoprobe HVCur-NPs towards those factors was designed and constructed. By modifying probe side chain with polypeptide, RVG29, we obtained brain-targeting HV-PEG-RVG29. It not only enables BBB penetration, but also produces near-infrared fluorescence (NIRF) and photoacoustic (PA) signals in cascade response to H2O2 and viscosity. The release of loaded curcumin (CUR) prevents oxidative stress, neuroinflammation and restore mitochondrial function so as to rescue PD phenotypes. In cellular PD model, HVCur-NPs generated NIRF/PA signals in response to elevated ROS and viscosity, and ameliorated cell apoptosis by eliminating ROS and restoring mitochondria function. Moreover, in mice PD model, HVCur-NPs realized in situ NIRF/PA imaging brain, and rescued DA neuron loss and restored the behavioral deficit of PD mice, without detectable biotoxicity. This carrier-free nanoprobe opens venues for integrated diagnosis and treatment of neurodegenerative diseases.

Platelet Extracellular Vesicles as Natural Delivery Vehicles for Mitochondrial Dysfunction Therapy?

Mitochondria are vital for energy production, metabolic regulation, and cellular signaling. Their dysfunction is strongly implicated in neurological, cardiovascular, and muscular degenerative diseases, where energy deficits and oxidative stress accelerate disease progression. Platelet extracellular vesicles (PEVs), once called "platelet dust", have emerged as promising agents for mitigating mitochondrial dysfunction. Like other extracellular vesicles (EVs), PEVs carry diverse molecular cargo and surface markers implicated in disease processes and therapeutic efficacy. Notably, they may possibly contain intact or partially functional mitochondrial components, making them tentatively attractive for targeting mitochondrial damage. Although direct research on PEVs-mediated mitochondrial rescue remains limited, current evidence suggests that PEVs can modulate diseases associated with mitochondrial dysfunction and potentially enhance mitochondrial health. This review explores the therapeutic potential of PEVs in neurodegenerative and cardiovascular disorders, highlighting their role in restoring mitochondrial health. By examining recent advancements in PEVs research, we aim to shed light on novel strategies for utilizing PEVs as therapeutic agents. Our goal is to underscore the importance of further fundamental and applied research into PEVs-based interventions, as innovative tools for combating a wide range of diseases linked to mitochondrial dysfunction.

Discovery of potential Leonurine-based therapeutic lead MJ210 attenuates Parkinson's disease pathogenesis via NF-κB and MAPK pathways: Mechanistic insights from in vitro and in vivo rotenone models

Parkinson's disease (PD) is a common neurodegenerative disease affecting motor and non-motor functions, with no effective treatment yet discovered. Neuroprotective compounds, both natural and synthetic, show promise but face challenges such as crossing the blood-brain barrier, limited serum stability, and higher toxicity. To tackle these obstacles, we have devised an innovative design strategy inspired by the neuroprotective properties of Leonurine, widely utilized in managing neurological disorders. Through rigorous screening of our compound library, we have identified a potent therapeutic molecule (MJ210) that exhibited remarkable efficacy in bolstering neuroprotection against rotenone-induced PD models, both in vitro and in vivo. Our findings revealed that administering MJ210 significantly increased neuronal survival in the SH-SY5Y model of PD. This was achieved by preventing apoptosis, reducing reactive oxygen species, mitigating mitochondrial dysfunction, and dampening neuroinflammation via ERK1/2-P38-JNK and P65-NFκB signaling pathways. In addition, MJ210 demonstrated remarkable neuroprotective abilities in vivo by significantly enhancing dopamine biosynthesis, alleviating motor dysfunction, improving balance and coordination, and reversing depression in rotenone-induced PD rats, even outperforming L-DOPA, the current gold standard treatment for PD. Therefore, MJ210 emerges as a significantly promising therapeutic candidate for PD, offering the potential for managing both the severity and progression of this disease.

New insights into pathogenisis and therapies of P2X7R in Parkinson's disease

Parkinson's disease (PD), a prevalent neurodegenerative disorder, is linked to genetics and environment, but its mechanisms remain unclear. Emerging evidence connects purinergic signaling-particularly ATP-sensitive P2X7 receptor (P2X7R)-to PD. P2X7R expression is elevated in PD patients, and its antagonist BBG mitigates 6-OHDA-induced dopaminergic neuron death. This review discusses P2X7R's structure, neural functions, PD-related mechanisms, and therapeutic potential as a targert.

Preventive effect of a garlic compound on astrocyte-mediated neuroinflammation in Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by dopaminergic neuron loss and resultant severe motor dysfunction. While current treatments primarily focus on maintaining dopamine levels, effective targeting of neuroinflammation, an important driver of disease progression, remains an unmet need. This study investigates the neuroprotective potential of BMDA (BMDA(N-benzyl-N-methyldecan-1-amine)), a natural compound derived from garlic with strong anti-inflammatory properties, using an MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine)-induced mouse model of PD. Behavioral assessments, immunohistochemistry, and dopamine analysis showed that BMDA effectively reduced neuroinflammation and preserved dopaminergic neurons. In vitro studies showed that BMDA significantly suppressed inflammatory markers and reduced astrocyte activation in MPP+-induced primary cultured astrocytes, and real-time PCR confirmed that BMDA attenuated proinflammatory cytokines and chemokines. Further mechanistic studies showed that BMDA inhibited the p-p65 and p-ERK signaling pathways, which underlie astrocyte-mediated neuroinflammation. These findings suggest that BMDA should be considered a therapeutic candidate for PD that targets neuroinflammation.

Liver fibrosis associated with more severe motor deficits in early Parkinson's disease

OBJECTIVE

To determine the impact of hepatic dysfunction on the motor manifestations of Parkinson's disease.

METHODS

We conducted a retrospective cohort study using data from the Parkinson's Progression Markers Initiative. Liver fibrosis was defined using the Fibrosis-4 score. Our primary outcome was the association of baseline Fibrosis-4 score with the Movement Disorders Society - Unified Parkinson's Disease Rating Scale (MDS-UPDRS) part III score. Additional outcomes were MDS-UPDRS part II, MDS-UPDRS part IV, Hoehn and Yahr stage, and levodopa equivalent daily dose. We used linear regression models to evaluate associations at baseline and 5 years after enrollment. We used linear mixed models to evaluate the association of liver fibrosis with the progression of motor dysfunction. Models were adjusted for demographics, comorbidities, alcohol use, time since Parkinson's disease diagnosis, levodopa equivalent daily dose, and genetic predisposition.

RESULTS

We included 360 people with Parkinson's disease with a mean age of 61.8 years (standard deviation 9.7) and 41.1 % women. There was a significant association between liver fibrosis and baseline MDS-UPDRS part III score (β=2.3, 95 % CI: 0.2, 4.5). Liver fibrosis was also correlated with higher interhemispheric signal asymmetry on DAT-SPECT scans in the anterior putamen (p < 0.05 by Wilcoxon rank sum test). There was no correlation with Fibrosis-4 score and any other motor assessment at baseline or after 5 years. Patients with elevated Fibrosis-4 scores had a slower rate of progression in MDS-UPDRS part III scores.

CONCLUSION

In people with Parkinson's disease, the presence of comorbid liver fibrosis was associated with more severe motor dysfunction early, but not later, within their disease course.

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.

Identification and Validation of Oxidative Stress-Related Hub Genes in Parkinson's Disease

Accumulating evidence suggests that oxidative stress plays a crucial role in the pathogenesis of Parkinson's disease (PD). The aims of this study were to identify oxidative stress-related hub genes, validate them through the construction of a diagnostic model, explore their interactions with miRNAs and transcription factors (TFs) and predict potential drug targets. Differentially expressed genes (DEGs) in the substantia nigra of PD patients were identified by analyzing a combination of datasets selected from the GEO database, including GSE7621, GSE20141, GSE49036, and GSE20163. The candidate genes associated with oxidative stress were screened by determining the overlap among the DEGs, oxidative stress-related genes (OSGs) and genes in key modules with the highest cor values identified via weighted gene coexpression network analysis (WGCNA). The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were used to perform functional enrichment analysis of these candidate genes. The hub genes were identified via protein-protein interaction (PPI) analysis, and receiver operating characteristic (ROC) curves were constructed to assess the diagnostic value of each hub gene. Then, a diagnostic model was constructed via least absolute shrinkage and selection operator (LASSO) regression with the hub genes identified above, and the model was further validated in external validation datasets (GSE20292 and GSE20164). Gene-miRNA and gene-TF regulatory networks were predicted via the miRNet database, whereas candidate drugs were predicted via the Drug-Gene Interaction database. After analysis of the intersection of the 7975 DEGs, 434 OSGs, and 3582 genes identified through WGCNA, 76 candidate genes were identified. A total of 9 hub genes (JUN, KEAP1, SRC, GPX5, MMP9, TXN, MAPK3, GPX2, and IL1A) were identified via PPI and ROC curve analyses. A diagnostic model with the ability to reliably predict PD on the basis of the identified hub genes (AUC = 0.925) was constructed. Further analysis of these 9 genes revealed 64 targeted miRNAs, 35 TFs in regulatory networks and 86 potential therapeutic agents. Nine hub genes related to oxidative stress in the pathogenesis of PD were identified. These genes show strong diagnostic performance and could serve as therapeutic targets. These findings might facilitate the development of promising candidate biomarkers and potential disease-modifying therapies for PD.

SIRT3-Mediated Deacetylation of DRP1K711 Prevents Mitochondrial Dysfunction in Parkinson's Disease

Dysregulation of mitochondrial dynamics is a key contributor to the pathogenesis of Parkinson's disease (PD). Aberrant mitochondrial fission induced by dynamin-related protein 1 (DRP1) causes mitochondrial dysfunction in dopaminergic (DA) neurons. However, the mechanism of DRP1 activation and its role in PD progression remain unclear. In this study, Mass spectrometry analysis is performed and identified a significant increased DRP1 acetylation at lysine residue 711 (K711) in the mitochondria under oxidative stress. Enhanced DRP1K711 acetylation facilitated DRP1 oligomerization, thereby exacerbating mitochondrial fragmentation and compromising the mitochondrial function. DRP1K711 acetylation also affects mitochondrial DRP1 recruitment and fission independent of canonical S616 phosphorylation. Further analysis reveals the critical role of sirtuin (SIRT)-3 in deacetylating DRP1K711, thereby regulating mitochondrial dynamics and function. SIRT3 agonists significantly inhibit DRP1K711 acetylation, rescue DA neuronal loss, and improve motor function in a PD mouse model. Conversely, selective knockout of SIRT3 in DA neurons exacerbates DRP1K711 acetylation, leading to increased DA neuronal damage, neuronal death, and worsened motor dysfunction. Notably, this study identifies a novel mechanism involving aberrant SIRT3-mediated DRP1 acetylation at K711 as a key driver of mitochondrial dysfunction and DA neuronal death in PD, revealing a potential target for PD treatment.

Mitochondrial Dysfunction as a Pathogenesis and Therapeutic Strategy for Metabolic-Dysfunction-Associated Steatotic Liver Disease

Metabolic-dysfunction-associated steatotic liver disease (MASLD) has emerged as a significant public health concern, attributed to its increasing prevalence and correlation with metabolic disorders, including obesity and type 2 diabetes. Recent research has highlighted that mitochondrial dysfunction can result in the accumulation of lipids in non-adipose tissues, as well as increased oxidative stress and inflammation. These factors are crucial in advancing the progression of MASLD. Despite advances in the understanding of MASLD pathophysiology, challenges remain in identifying effective therapeutic strategies targeting mitochondrial dysfunction. This review aims to consolidate current knowledge on how mitochondrial imbalance affects the development and progression of MASLD, while addressing existing research gaps and potential avenues for future research. This review was conducted after a systematic search of comprehensive academic databases such as PubMed, Embase, and Web of Science to gather information on mitochondrial dysfunction as well as mitochondrial-based treatments for MASLD.

Neuroprotective Activities of Sertraline, Tiagabine, and Bicifadine with Autophagy-Inducing Potentials in a 6-Hydroxidopamine-Treated Parkinson's Disease Cell Model

Parkinson's disease (PD) is one of neurodegenerative diseases characterized by the progressive loss of dopaminergic neurons in the substantia nigra. The development of a neuroprotective therapy is crucial for mitigating features and progression of PD. Since autophagy induction has recently emerged as a promising neuroprotective strategy, this study aimed to identify autophagy-inducing compounds and evaluate their neuroprotective activity. Among 3,200 compounds consisting of FDA-approved drugs or are under active development, 547 compounds targeting neurological diseases were filtered in, and three compounds (sertraline, tiagabine and bicifadine) were finally identified to exhibit the autophagy-inducing activity and also demonstrated the autophagy-dependent neuroprotective action by inhibiting the mammalian target of rapamycin (mTOR) in 6-hydroxydopamine (6-OHDA)-induced neurotoxicity in PC12 cells. Furthermore, the analysis of neurochemical changes suggested that the ability of those compounds to restore the quantity of cellular neurotransmitters such as betaine, 5-hydroxyindoleacetic acid and kynurenine might be linked to their neuroprotective function. In conclusion, compounds like sertraline, tiagabine, and bicifadine that have the ability to induce autophagy and inhibit mTOR might be repurposed as PD treatment to protect the neuronal cells.

Biomimetic Nanoparticles Enhance Recovery of Movement Disorders in Parkinson's Disease by Improving Microglial Mitochondrial Homeostasis and Suppressing Neuroinflammation

Neuroinflammation is a key risk factor for cognitive impairment, and microglia are the main drivers. Metformin has been shown to suppress inflammation and reduce microglial activation, protecting neurons from damage. However, its clinical efficacy is limited by low bioavailability and metabolic challenges, especially in terms of precise delivery to specific targets. To overcome this problem, we developed biomimetic microglial nanoparticles (MePN@BM) to enhance the targeted delivery and bioavailability of metformin. Through homologous targeting, the delivery efficiency of drugs in the inflammatory site of Parkinson's disease was enhanced to improve the therapeutic effect. The results showed that MePN@BM effectively delivers metformin to the brain, promotes autophagy, restores mitochondrial membrane potential, and reduces oxidative stress. In a Parkinson's disease (PD) mouse model, MePN@BM improved motor function, repaired dopaminergic neurons, and cleared α-synuclein aggregates. Notably, transcriptome analysis revealed enriched inflammation-related pathways, and immunofluorescence showed that PD mice treated with MePN@BM had higher levels of anti-inflammatory factors and lower levels of pro-inflammatory factors. Therefore, it provides a promising strategy for the treatment of inflammation-mediated motor dysfunction.

Reduced composite dietary antioxidant index increases the risk of Parkinson's disease and all-cause mortality in Parkinson's disease patients: evidence from the NHANES database

Background

This study aimed to investigate the relationship between the Composite Dietary Antioxidant Index (CDAI) and the prevalence of Parkinson's disease (PD), as well as to explore its relationship with all-cause mortality risk in PD patients.

Methods

Data from the National Health and Nutrition Examination Survey (NHANES) database spanning from 2007 to 2018 were used, including 119,609 participants. After excluding individuals aged <18 years, those with incomplete follow-up data, and those missing critical variables such as CDAI and covariates, the final cohort consisted of 34,133 participants. Participants were categorized into a PD group (510 individuals) and a non-PD group (33,623 individuals). The CDAI values were calculated, and participants were divided into three groups based on the tertile distribution of their CDAI scores: Q1 (CDAI < -1.07), Q2 (-1.07 to 1.74), and Q3 (CDAI >1.74). Weighted logistic regression and weighted Cox regression analyses were employed to evaluate the associations between CDAI and the prevalence of PD, as well as between CDAI and all-cause mortality risk. Restricted cubic spline regression analysis was used to further elucidate the precise relationship between CDAI and outcome events.

Results

CDAI values were significantly lower in the PD group compared to the non-PD group. After adjusting for age, sex, comorbid conditions (hypertension and diabetes), blood lipid and glucose levels, a reduction in CDAI was associated with an increased risk of PD (Q3 vs. Q1, OR = 0.72, p = 0.035). In patients with PD, a decrease in CDAI was significantly associated with a higher risk of all-cause mortality (Q3 vs. Q1, HR = 0.53, p = 0.018). This association was particularly pronounced in those over 60 years old, smokers, and those with hypertension. Restricted cubic spline regression analysis identified CDAI <0.471 as a risk factor for PD, and CDAI <0.527 as a risk factor for all-cause mortality in PD patients.

Conclusion

CDAI reduction is an independent risk factor for both PD risk in the general population and all-cause mortality in PD patients, with amplified predictive power in older adults, smokers, and hypertensive individuals. Our findings support developing personalized antioxidant-enhancing nutritional interventions for both high-risk populations with suboptimal CDAI and established PD patients.

Environmental Factors Exacerbate Parkinsonian Phenotypes in an Asian-Specific Knock-In LRRK2 Risk Variant in Mice

Parkinson's disease (PD) is a neurodegenerative disorder affecting nearly 10 million people worldwide, and for which no cure is currently known. Mutations in the Leucine-Rich Repeat Kinase 2 (LRRK2) gene, age, as well as environmental factors such as neurotoxin exposure and stress, are known to increase the risk of developing the disease in humans. To investigate the role of a specific Asian variant of the LRRK2 gene to induce susceptibility to stress and trigger PD phenotypes with time, knock-in (KI) mice bearing the human LRRK2 R1628P risk variant have been generated and studied from 2 to 16 months of age in the presence (or absence) of stress insults, including neurotoxin injections and chronic mild stress applied at 3 months of age. Pathophysiological and behavioural phenotypes have been measured at different ages and primary neurons and fibroblast cells were cultured from the KI mouse line and treated with H2O2 to study susceptibility towards oxidative stress in vitro. KI mice displayed specific PD features and these phenotypes were aggravated by environmental stresses. In particular, KI mice developed locomotion impairment and increased constipation. In addition, dopamine-related proteins were dysregulated in KI mice brains: Dopamine transporter (DAT) was decreased in the midbrain and striatum and dopamine levels were increased. Primary fibroblast cells and cortical neurons from KI mice also displayed increased susceptibility to oxidative stress. Therefore, the LRRK2 R1628P KI mice are an excellent model to study the progressive development of PD.

The interplay between α-synuclein aggregation and necroptosis in Parkinson's disease: a spatiotemporal perspective

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by the death of dopaminergic neurons and the aggregation of alpha-synuclein (α-Syn). It presents with prominent motor symptoms, and by the time of diagnosis, a significant number of neurons have already been lost. Current medications can only alleviate symptoms but cannot halt disease progression. Studies have confirmed that both dopaminergic neuronal loss and α-Syn aggregation are associated with necroptosis mechanisms. Necroptosis, a regulated form of cell death, has been recognized as an underexplored hotspot in PD pathogenesis research. In this review, we propose a spatiotemporal model of PD progression, highlighting the interactions between α-Syn aggregation, mitochondrial dysfunction, oxidative stress, neuroinflammation and necroptosis. These processes not only drive motor symptoms but also contribute to early non-motor symptoms, offering insights into potential diagnostic markers. Finally, we touch upon the therapeutic potential of necroptosis inhibition in enhancing current PD treatments, such as L-Dopa. This review aims to provide a new perspective on the pathogenesis of PD and to identify avenues for the development of more effective therapeutic strategies.

Fucoxanthinol Mitigates the Cytotoxic Effect of Chlorpyrifos and MPTP on the Dopaminergic Differentiation of SH-SY5Y Human Neuroblastoma Cells

This study investigates the neuroprotective effects of fucoxanthinol (FXL) against the toxic activities of two compounds known to induce neurotoxic effects in humans and animals. MPTP (1-methyl- 4-phenyl- 1,2,3,6-tetrahydropyridine) induces Parkinson's disease (PD)-like phenotypes by inhibiting mitochondrial complex I in dopaminergic neurons. Chlorpyrifos (CPF), another neurotoxic agent, is associated with acute and long-term neurotoxicity primarily through acetylcholinesterase (AChE) inhibition. FXL demonstrated the ability to reverse the neurotoxic effects of CPF and MPTP in SH-SY5Y dopaminergic neuronal cell models. Treatment with FXL enhances mitochondrial function in SH-SY5Y cells exposed to CPF and MPTP, as demonstrated by increased levels of Adenosine triphosphate (ATP), mitochondrial membrane potential (MMP), mitochondrial complexes activities, and oxygen consumption rates, pyruvate dehydrogenase (PDH) activities, and mitophagy pathways. This improvement highlights FXL's ability to counteract the mitochondrial dysfunction induced by these neurotoxic agents. Additionally, FXL reduces oxidative damage and enhances cell viability. At the molecular level, the neuroprotective effects were also associated with the modulation of apoptotic cell markers, including Bcl- 2 and the oxidative damage markers. Molecular docking data further support the outcomes of our in vitro studies. Multivariable analysis highlights the neuroprotective effects of FXL. These findings indicate the potential of FXL to mitigate CPF- and MPTP-induced neurotoxicity, suggesting its promise as a therapeutic agent for managing neuronal damage observe in PD.

Protective effects of harpagoside on mitochondrial functions in rotenone‑induced cell models of Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease. Currently, no radical treatment is available for this disease. Harpagoside is a proposed neuroprotective iridoid active ingredient that can be derived from Scrophulariae buergeriana, Scrophularia striata and Harpagophytum procumbens. The present study aimed to investigate the effects of harpagoside on mitochondrial functions in rotenone-induced cell models of Parkinson's disease (PD). Neuro-2A (N2A) cells were treated with rotenone to establish in vitro cell models of PD. Cell viability and survival were measured using a Cell Counting Kit-8 assay. Biochemical assays with spectrophotometry were used to measure complex I activity, mitochondrial swelling and caspase 3 activity. The cell survival rate was first found to be significantly decreased by rotenone (20 nmol/l) treatment. However, intervention with harpagoside (10 µmol/l) was found to increase the cell survival rate of rotenone-induced N2A cell models differentiated with 1 mmol/l of dibutyryl-cAMP. At ≥0.1 µmol/l concentration, harpagoside significantly alleviated rotenone-induced mitochondrial swelling, whereas at 1 µmol/l it significantly counteracted the inhibitory effects of rotenone on complex I activity. At 10 µmol/l harpagoside significantly inhibited rotenone-induced caspase 3 activation. These results suggest that harpagoside has the potential to protect mitochondrial functions against rotenone-induced injury in N2A cell models of PD.

Retinal changes detected by diffuse reflectance spectroscopy in parkinsonian monkeys

Significance

Parkinson's disease (PD) is diagnosed when 50% neurodegeneration has occurred. The retina could provide biomarkers that would allow for earlier diagnosis. Retinal spectroscopy is a technique that could be used to find such biomarkers.

Aim

We aimed to find new diagnostic biomarkers for PD following detailed spectral examinations of the retina.

Approach

The newly developed Zilia Ocular device was used to perform spectrometric scans of the optic nerve head (ONH) and the retina of four cynomolgus monkeys (Macaca fascicularis) before and after the administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), a neurotoxin used to produce the gold-standard animal model of PD. From the spectrometric data, the blood oximetry was calculated, and the diffuse reflectance spectra (DRS) were analyzed to find variations between the two experimental conditions. Post-mortem analyses were also performed on the retina of the four parkinsonian monkeys and four additional control animals.

Results

The analysis of the DRS indicated a lower slope between the 480- and 525-nm wavelengths in both the ONH and the retina. Post-mortem measurements of the retinal layer thicknesses showed that the outer nuclear layer was significantly thinner in MPTP-intoxicated monkeys, compared with controls. Altogether, these results indicate that MPTP altered the optical properties of the ONH and the retina and show that these variations might be explained by MPTP-induced structural changes in the eye fundus, as observed post-mortem.

Conclusions

Overall, our results indicate that spectroscopy could be used as a noninvasive method to detect changes in the retina that occur in PD and that such changes could represent retinal biomarkers for improved diagnosis.

Exploring patterns of multimorbidity in South Korea using exploratory factor analysis and non negative matrix factorization

The increasing prevalence of multimorbidity and the co-occurrence of multiple chronic diseases presents a measurable challenge to public health, impacting healthcare strategies and planning. This study aimed to explore disease patterns and temporal clustering using data from South Korea's National Health Insurance Service, spanning 2002-2019. The dataset included approximately 1 million individuals, focusing on those with at least two chronic diseases while excluding individuals who died within five years of follow-up. We analyzed 126 non-communicable diseases, considering only those with a prevalence above 1%, and applied a wash-out period to determine incidence. Exploratory factor analysis (EFA) and non-negative matrix factorization (NMF) were used to identify disease clustering over time. Participants were divided into four groups: men and women in their 50 s and 60 s. EFA identified five patterns in men in their 50 s and seven in their 60 s, while four patterns emerged in women in their 50 s and five in their 60 s. NMF identified 10 clusters for men in their 50 s, 15 in their 60 s, and 16 clusters for women in both age groups. Our study confirms established comorbidity patterns and reveals previously unrecognized clusters, providing data-driven insights into multimorbidity mechanisms and supporting evidence-based healthcare strategies.

Identification of Key Active Constituents in Eucommia ulmoides Oliv. Leaves Against Parkinson's Disease and the Alleviative Effects via 4E-BP1 Up-Regulation

Parkinson's disease (PD) is the second most common progressive neurodegenerative disorder, affecting an increasing number of older adults. Despite extensive research, a definitive cure remains elusive. Eucommia ulmoides Oliv. leaves (EUOL) have been reported to exhibit protective effects on neurodegenerative diseases, however, their efficacy, key active constituents, and pharmacological mechanisms are not yet understood. This study aims to explore the optimal constituents of EUOL regarding anti-PD activity and its underlying mechanisms. Using a zebrafish PD model, we found that the 30% ethanol fraction extract (EF) of EUOL significantly relieved MPTP-induced locomotor impairments, increased the length of dopaminergic neurons, inhibited the loss of neuronal vasculature, and regulated the misexpression of autophagy-related genes (α-syn, lc3b, p62, and atg7). Assays of key regulators involved in PD further verified the potential of the 30% EF against PD in the cellular PD model. Reverse phase protein array (RPPA) analysis revealed that 30% EF exerted anti-PD activity by activating 4E-BP1, which was confirmed by Western blotting. Phytochemical analysis indicated that cryptochlorogenic acid, chlorogenic acid, asperuloside, caffeic acid, and asperulosidic acid are the main components of the 30% EF. Molecular docking and surface plasmon resonance (SPR) indicated that the main components of the 30% EF exhibited favorable binding interactions with 4E-BP1, further highlighting the roles of 4E-BP1 in this process. Accordingly, these components were observed to ameliorate PD-like behaviors in the zebrafish model. Overall, this study revealed that the 30% EF is the key active constituent of EUOL, which had considerable ameliorative effects on PD by up-regulating 4E-BP1. This suggests that EUOL could serve as a promising candidate for the development of novel functional foods aimed at supporting PD treatment.

Sitagliptin attenuates L-dopa-induced dyskinesia by regulating mitochondrial proteins and neuronal activity in a 6-OHDA-induced mouse model of Parkinson's disease

L-dopa-induced dyskinesia (LID) is an incapacitating complication of long-term administration of L-dopa therapy that commonly affects patients with Parkinson's disease (PD) due to the widespread use of the causative drug. Herein, we investigated the therapeutic potential of sitagliptin, a drug used to treat type 2 diabetes mellitus, to treat LID. 6-hydroxydopamine (6-OHDA) was unilaterally injected into the left side of the substantia nigra pas compacta to induce a mouse model of PD. After four weeks of 6-OHDA induction, L-dopa was administered with or without sitagliptin for 11 consecutive days. LID was monitored using abnormal involuntary movement (AIM) scoring, conducted on days 5 and 10 of L-dopa treatment. Comparative proteomic analysis was performed on the 6-OHDA-lesioned striatum by comparing groups treated with vehicle + L-dopa and sitagliptin + L-dopa. Sitagliptin combined with L-dopa significantly attenuated AIM scores in 6-OHDA-lesioned mice. Proteomic analysis following sitagliptin treatment showed an increase in proteins involved in mitochondrial function regulation and a decrease in proteins associated with cytoskeleton function regulation. Changes in the expression of Ndufb2, a subunit of NADH: ubiquinone oxidoreductase (complex I), and Arc, an immediate early gene (IEG), which showed the most significant increase and decrease, respectively, were validated using western blotting and RT-PCR analysis. These findings suggest that sitagliptin may have therapeutic potential by enhancing mitochondrial functions and suppressing neuronal activity in the striatum, thereby mitigating the incapacitating complications associated with long-term L-dopa use in patients with PD.

Neurotoxic Effects of Atrazine on Dopaminergic System via miRNAs and Energy-Sensing Pathways

Atrazine (ATR, 2-chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine) is a globally prevalent herbicide known to induce dopaminergic neurotoxicity at high concentrations. MicroRNAs (miRNAs), pivotal in regulating gene expression post-transcriptionally, play essential roles in neuronal differentiation, proliferation, and apoptosis. This study investigates the effects of ATR on the dopaminergic system and behavioral responses in rats, with a particular focus on critical dopaminergic proteins such as tyrosine hydroxylase (TH), nuclear receptor related-1 protein (NURR1), and α-synuclein. The results reveal that ATR exposure significantly reduces the expression of TH and NURR1, while elevating levels of α-synuclein. Through miRNA sequencing and proteomic analysis, we identify alterations in miRNA and protein profiles that are intricately linked to the development of the dopaminergic system. Notably, treatment with ATR results in a marked increase in AMPK levels concurrent with a decrease in miR-322-5p. The differentially expressed genes associated with ATR exposure primarily influence the dopaminergic system by engaging in critical pathways such as AMPK, mTOR, autophagy, FoxO, and HIPPO. This study underscores the neurotoxic impact of ATR on the dopaminergic system via miRNA regulatory mechanisms and energy-sensing pathways, including AMPK and SIRT1, providing a molecular foundation for developing strategies to prevent and treat neurotoxicity induced by ATR exposure.

Characterization and neurotherapeutic evaluation of venom polypeptides identified from Vespa magnifica: The role of Mastoparan-M in Parkinson's disease intervention

ETHNOPHARMACOLOGICAL RELEVANCE

Parkinson's disease (PD) is a common neurodegenerative disorder in the elderly, characterized by the loss of dopaminergic neurons in the substantia nigra and the formation of Lewy bodies. Hufeng Jiu from Vespa magnifica Smith, a traditional remedy used by the Chinese Jingpo minority, is documented in the Pharmacopoeia of China (2020) for treating rheumatic arthritis. Notably, recent research suggests that components of wasp venom (WV) from Vespa magnifica Smith, particularly polypeptides such as Mastoparan-M (Mast-M) and Vespakinin-M, may have potential therapeutic effects for neurological disorders. However, the specific polypeptide components of WV and their therapeutic effects on PD models remain insufficiently understood.

AIM OF THE STUDY

This study aims to characterize the neuroactive polypeptides in Vespa magnifica Smith venom and investigate the therapeutic potential of Mast-M for PD.

MATERIALS AND METHODS

Neuroactive polypeptides in WV were identified using LC/MS, and Mast-M derived from venom of Vespa magnifica Smith was verified with HPLC. The neuroprotective effects of WV and its peptides were assessed using the CCK-8 assay in 1-methyl-4- phenylpyridinium (MPP+)-induced SH-SY5Y human neuroblastoma cells. Mast-M was identified as a potent antagonist against MPP+-induced neurotoxicity. The toxicity, hemolytic activity, and blood-brain-barrier (BBB) permeability of Mast-M were evaluated in mice, and its therapeutic effects were assessed in an MPTP-induced PD mouse model, focusing on motor function and tyrosine hydroxylase (TH) levels. Additionally, Mast-M's impact on mitochondrial membrane potential (MMP), autophagy, and the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR) signling pathway was investigated.

RESULTS

A total of 1007 peptides were identified in the WV, including 187 UniProtKB unreviewed, with 185 predicted to be BBB-permeability. Our results show that Mast-M exhibits a time-dependent distribution in mice, initially localizing in the peritoneal region and subsequently accumulating in the brain, liver, and kidney. Cellular uptake studies reveal that Mast-M penetrates cell membranes and accumulates intracellularly over time. In the MPP+-induced neurotoxicity model using SH-SY5Y cells, Mast-M significantly enhances cell viability and MMP. In vivo safety assessments indicate that Mast-M is well-tolerated at doses up to 100 μg/kg, with no significant toxicological effects observed. However, higher doses induce hepatic distress, necessitating dose optimization. Hemolysis was absent at concentrations ≤37 μg/mL, with an EC50 for hemolytic activity of 197 μg/mL. In MPTP-induced PD models, Mast-M partially ameliorates motor deficits and preserves TH expression in dopaminergic neurons, supporting its neuroprotective role. Mechanistically, Mast-M activates autophagic pathways, as evidenced by the upregulation of autophagy-related protein LC3 in MPP+-challenged SH-SY5Y cells. Furthermore, Mast-M promotes mitophagy and mitochondrial biogenesis, modulating the AMPK/mTOR signaling axis to facilitate mitochondrial turnover.

CONCLUSION

Mast-M emerges as a promising therapeutic candidate for PD, capable of crossing the BBB, enhancing autophagy, and providing neuroprotection in PD models. Further studies are warranted to optimize dosing and elucidate its full therapeutic potential.

Tau association with synaptic mitochondria coincides with energetic dysfunction and excitatory synapse loss in the P301S tauopathy mouse model

Neurodegenerative Tauopathies are a part of several neurological disorders and aging-related diseases including, but not limited to, Alzheimer's Disease, Frontotemporal Dementia with Parkinsonism, and Chronic Traumatic Encephalopathy. The major hallmarks present in these conditions include Tau pathology (composed of hyperphosphorylated Tau tangles) and synaptic loss. in vivo studies linking Tau pathology and mitochondrial alterations at the synapse, an avenue that could lead to synaptic loss, remain predominantly scarce. For this reason, using 3-month-old wild-type and human mutant Tau P301S transgenic mice, we investigated the association of Tau with mitochondria, synaptosome bioenergetics, and characterized excitatory synaptic loss across hippocampal regions (Dentate Gyrus, perisomatic CA3, and perisomatic CA1) and in the parietal cortex. We found a significant loss of excitatory synapses in the parietal cortex and hippocampal Dentate Gyrus (DG) of Tau P301S mice. Furthermore, we found that Tau (total and disease-relevant phosphorylated Tau) associates with both the non-synaptic and synaptic mitochondria of Tau P301S mice and this coincided with synaptic mitochondrial dysfunction. The findings presented here suggest that Tau associates with mitochondria at the synapse, leading to synaptic mitochondrial dysfunction, and likely contributing to synaptic loss.

Adenine Nucleotide Translocase 1 Promotes Functional Integrity of Mitochondria via Activating DDIT3-CytC Pathway and Intensifying Actin Filament Structures

Adenine nucleotide translocase 1 (ANT1), involved in exchanging ATP and ADP across the mitochondrial inner membrane, is downregulated in mouse brains with Parkinsonian variations. To further explore the role of ANT1 in neuronal cells, an intensive investigation was conducted by introducing overexpressed ANT1 and ANT1 mutant at Asn177 into neuroblastoma SH-SY5Y cells treated with MPP+. Consequently, ANT1 was found to be involved in maintaining mitochondrial functions by attenuating ROS levels and ameliorating a long-lasting mPTPs opening and aberrant mitochondrial membrane potential (△Ψm) induced by MPP+. RNA-Seq analysis revealed that the processes including respiration, mitochondrial transporting, mitochondrial organization and apoptosis were highly facilitated in response to ANT1 supplement under MPP+ treatment. Additionally, ANT1 enrichment promoted a clearance of the damaged cells via activating the DDIT3-CytC-related pathway and resulted in an intensified structure of actin microfilaments. However, ANT1 mutant served as a causative factor, since it led to mitochondrial dysfunction via promoting a long-lasting mPTPs opening, inactivating DDIT3-CytC-related pathway and strongly impairing actin microfilaments. These observations are helpful to improve the understanding of the role of ANT1 in regulating mitochondrial functions in neuronal cells and to explore a potential therapeutic implication of ANT1 for Parkinson's disease as a promising target.

SIRT1 Alleviates Oxidative Stress-Induced Mitochondrial Dysfunction and Mitochondria-Associated Membrane Dysregulation in Stress Urinary Incontinence

The pathogenesis of stress urinary incontinence (SUI), a condition common in women, remains to be fully elucidated. This study revealed that the incidence of SUI is associated with mitochondrial homeostasis dysregulation following oxidative stress in the fibrous connective tissue of the pelvic floor. SIRT1 is an essential factor for maintaining mitochondrial homeostasis; however, its potential role and mechanism of action in SUI pathogenesis remain unclear. Both in vitro and in vivo, we observed that oxidative stress reduced SIRT1 expression to inhibit the PGC-1α/NRF1/TFAM and PINK1/Parkin signalling pathways, eliciting impairment of mitochondrial biogenesis and mitophagy in L929 cells and SUI mice. Decreased SIRT1 levels induced endoplasmic reticulum (ER) stress and altered the structure of mitochondria-associated membranes (MAMs), disrupting ER-mitochondrial calcium homeostasis and exacerbting ROS accumulation. SIRT1 activation can restore mitochondrial function and the structure of MAMs and alleviate ER stress in fibroblasts, promoting anterior vaginal wall repair and improving urodynamic parameters in the SUI model. Our findings provide novel insights into the role and associated mechanism of SIRT1 in ameliorating oxidative stress-induced mitochondrial dysfunction in fibroblasts of the anterior vaginal wall and propose SIRT1 as a potential therapeutic target for SUI.

Gut microbiota: A new window for the prevention and treatment of neuropsychiatric disease

Under normal physiological conditions, gut microbiota and host mutually coexist. They play key roles in maintaining intestinal barrier integrity, absorption, and metabolism, as well as promoting the development of the central nervous system (CNS) and emotional regulation. The dysregulation of gut microbiota homeostasis has attracted significant research interest, specifically in its impact on neurological and psychiatric disorders. Recent studies have highlighted the important role of the gut- brain axis in conditions including Alzheimer's Disease (AD), Parkinson's Disease (PD), and depression. This review aims to elucidate the regulatory mechanisms by which gut microbiota affect the progression of CNS disorders via the gut-brain axis. Additionally, we discuss the current research landscape, identify gaps, and propose future directions for microbial interventions against these diseases. Finally, we provide a theoretical reference for clinical treatment strategies and drug development for AD, PD, and depression.

Single-cell analysis of CD14+CD16+ monocytes identifies a subpopulation with an enhanced migratory and inflammatory phenotype

Monocytes in the central nervous system (CNS) play a pivotal role in surveillance and homeostasis, and can exacerbate pathogenic processes during injury, infection, or inflammation. CD14+CD16+ monocytes exhibit diverse functions and contribute to neuroinflammatory diseases, including HIV-associated neurocognitive impairment (HIV-NCI). Analysis of human CD14+CD16+ monocytes matured in vitro by single-cell RNA sequencing identified a heterogenous population of nine clusters. Ingenuity pathway analysis of differentially expressed genes in each cluster identified increased migratory and inflammatory pathways for a group of clusters, which we termed Group 1 monocytes. Group 1 monocytes, distinguished by increased ALCAM, CD52, CD63, and SDC2, exhibited gene expression signatures implicated in CNS inflammatory diseases, produced higher levels of CXCL12, IL-1Ra, IL-6, IL-10, TNFα, and ROS, and preferentially transmigrated across a human in vitro blood-brain barrier model. Thus, Group 1 cells within the CD14+CD16+ monocyte subset are likely to be major contributors to neuroinflammatory diseases.

Targeting the ClpP-αSynuclein Interaction with a Decoy Peptide to Mitigate Neuropathology in Parkinson's Disease Models

Parkinson's disease (PD), the most prevalent neurodegenerative movement disorder, is characterized by the progressive loss of dopaminergic (DA) neurons and the accumulation of α-synuclein (αSyn)-rich inclusions. Despite advances in understanding PD pathophysiology, disease-modifying therapies remain elusive, underscoring gaps in our knowledge of its underlying mechanisms. Mitochondria are key targets of αSyn toxicity, and growing evidence suggests that αSyn-mitochondrial interactions contribute to PD progression. Our recent findings identify mitochondrial protease ClpP as a crucial regulator of αSyn pathology, with pathological αSyn binding to and impairing ClpP function, thereby exacerbating mitochondrial impairment and neurodegeneration. To disrupt this deleterious interaction, we developed a decoy peptide, CS2, which directly binds to the non-amyloid-β component (NAC) domain of αSyn, preventing its association with ClpP. CS2 treatment effectively mitigated αSyn toxicity in an αSyn-stable neuronal cell line, primary cortical neurons inoculated with αSyn pre-formed fibrils (PFFs), and DA neurons derived from PD patient-induced pluripotent stem cells (iPSCs). Notably, subcutaneous administration of CS2 in transgenic mThy1-hSNCA PD mice rescued cognitive and motor deficits while reducing αSyn aggregation and neuropathology. These findings establish the ClpP-αSyn interaction as a druggable target in PD and position CS2 as a promising therapeutic candidate for PD and other αSyn-associated neurodegenerative disorders.

The 5-HT1F Receptor Agonist Lasmiditan improves Cognition and Ameliorates Associated Cortico-Hippocampal Pathology in Aging Parkinsonian Mice

While the etiopathology of Parkinson's disease (PD) is complex, mitochondrial dysfunction is established to have a central role. Thus, mitochondria have emerged as targets of therapeutic interventions aiming to slow or modify PD progression. We have previously identified serotonergic 5-HT1F receptors as novel mediators of mitochondrial biogenesis (MB) - the process of producing new mitochondria. Given this, here, we assessed the therapeutic potential of the FDA-approved 5-HT1F receptor agonist, lasmiditan, in a chronic progressive PD model (Thy1-aSyn 'line 61' mice). It was observed that systemic lasmiditan exhibited robust brain penetration and reversed cognitive deficits in young (4-5.5 months old) Thy1-aSyn mice (1mg/kg, every other day). Anxiety-like behavior was also improved while motor function remained unaffected. These behavioral changes were associated with enhanced MB and mitochondrial function, paired with reduced alpha-synuclein aggregation particularly in cortico-hippocampal regions. Furthermore, in older (10-11.5 months old) mice, although the effects were milder, daily lasmiditan administration increased MB and bettered cognitive abilities. In essence, these findings indicate that repurposing lasmiditan could be a potent strategy to address PD-related cognitive decline.

Glycolytic pathways: The hidden regulators in Parkinson's disease

Parkinson's disease (PD) is a widespread neurodegenerative condition [1]; however, its association with glycolysis, specifically the activity of genes related to glycolysis, has not yet been explored. We downloaded 3 datasets related to PD from the GEO database and identified the glycolytic genes related to PD. Subsequently, GO and KEGG enrichment analyses were conducted. We constructed a PD diagnosis model using the SVM algorithm for differentially expressed glycolysis-related genes and verified the model with LASSO regression analysis. Next, we constructed a regulatory network of genes that were differentially expressed with respect to glycolysis. Finally, the amount of immune cell infiltration was analyzed in PD samples, and the correlation between differential genes and immune cells was calculated. A total of 64 differentially expressed glycolytic genes associated with PD were screened. Then, a GO analysis was conducted, followed by KEGG and GASE enrichment analyses. Within the established PD diagnostic model, 26 genes that were differentially expressed and linked to glycolysis showed strong statistical significance. After further screening, a diagnostic model for PD including seven key genes was established. Further analysis showed that ABHD5 most strongly correlated with neutrophils (r = 0.507). The key gene SMAD3 was strongly negatively associated with gamma delta T cells (r = -0.488). This research offered a theoretical foundation for the association between glycolysis and PD. Seven glycolytic genes were identified as significantly linked to PD and warrant additional research.

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.

Unraveling the role of Nrf2 in dopaminergic neurons: a review of oxidative stress and mitochondrial dysfunction in Parkinson's disease

Nuclear factor erythroid 2-related factor 2 (Nrf2) is an essential transcriptional factor, involved in the regulation of countenance of various anti-oxidant enzymes and cytoprotective genes that respond to mitochondrial dysfunctions, oxidative stress, and neuroinflammation, thus potentially contributing to several neurodegenerative diseases (NDDs), including Parkison's disease (PD). PD is the second most prevalent progressive NDD, characterized by gradual neuronal death in substantia nigra pars compacta (SNpc), depletion of dopamine level, and a wide range of motor symptoms, including bradykinesia, tremor, tingling, and muscle fatigue. The etiopathology of PD is caused by multifactorial intertwined with the onset and progression of the disease. In this context, Nrf2 exhibits neuroprotective action by preserving dopaminergic neurons in the striatum and retarding the disease progression; thus, Nrf2 activation plays a crucial role in PD. Additionally, Nrf2 binds with the antioxidant response element, which is located in the promoter region of most of the genes that are responsible for coding antioxidant enzymes. Moreover, protein kinase C (PKC) mitogen-activated protein kinase (MAPK), and phosphatidylinositol 3-kinase (PI3K) are also involved in the regulation of Keap1 pathway-mediated Nrf2 activation. As Nrf2 revealed its defensive and protective role in the central nervous system (CNS), it is gaining enough interest in treating PD. The treatments that are currently available are intended to alleviate the symptoms of PD; however, they are unable to halt the progression and severity of the disease. Therefore, in this review we delve deeper into various molecular mechanisms associated with oxidative stress, mitochondrial dysfunction, and neuroinflammation in PD. Additionally, we elaborated on the substantial role that NRF2 plays in mitigating these adverse effects and its potential as a therapeutic target.

The emerging role of oxygen redox in pathological progression of disorders

Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington disease, pose serious threats to human health, leading to substantial economic burdens on society and families. Despite extensive research, the underlying mechanisms driving these diseases remain incompletely understood, impeding effective diagnosis and treatment. In recent years, growing evidence has highlighted the crucial role of oxidative stress in the pathogenesis of various neurodegenerative diseases. However, there is still a lack of comprehensive reviews that systematically summarize the impact of mitochondrial oxidative stress on neurodegenerative diseases. This review aims to address this gap by summarizing the molecular mechanisms by which mitochondrial oxidative stress promotes the initiation and progression of neurodegenerative disorders. Furthermore, it discusses the potential of antioxidant-based therapeutic strategies for the treatment of these diseases. By shedding light on the role of mitochondrial oxidative stress in neurodegenerative diseases, this review not only serves as a valuable reference for further research on the disease mechanisms, but also offers novel perspectives for the treatment of these disorders.

1,4-dihydroxy-2-naphthoic acid prevents 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced motor function deficits

Parkinson's disease (PD), characterized by death of dopaminergic neurons in the substantia nigra, is the second most prevalent progressive neurodegenerative disease. However, the etiology of PD is largely elusive. This study employed the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) rodent model to examine the effectiveness of 1,4-dihydroxy-2-naphthoic acid (1,4-DHNA), an aryl hydrocarbon receptor (AhR) active gut bacteria-derived metabolite, in mitigating MPTP's motoric deficits, and the role of AhR in mediating these effects. Male C57BL/6 mice were fed daily with vehicle, 20 mg/kg 1,4-DHNA, or AhR-inactive isomer 3,7-DHNA, for 3 weeks before administration of 80 mg/kg MPTP or vehicle. Four weeks later, mice were assessed for motoric functions. Both 1,4-DHNA and 3,7-DHNA prevented MPTP-induced deficits in the motor pole test and in the adhesive strip removal test. Additionally, 1,4-DHNA improved balance beam performance and completely prevented MPTP-induced reduction in stride length. In contrast, 3,7-DHNA, an AhR-inactive compound, did not improve balance beam performance and had only a partial effect on stride length. This study suggests that natural metabolites of gut microbiota, such as 1,4-DHNA, could be beneficial to counteract the development of motor deficits observed in PD. Thus, this study further supports the hypothesis that pathological and mitigating processes in the gut could play an essential role in PD development. Moreover, this indicates that 1,4-DHNA's ability to combat various motor deficits is likely mediated via multiple underlying molecular mechanisms. Specifically, AhR is involved, at least partially, in control of gait and bradykinesia, but it likely does not mediate the effects on fine motor skills.

Oxidative stress and mitochondrial impairment: Key drivers in neurodegenerative disorders

Mitochondrial dysfunction and oxidative stress are critical factors in the pathogenesis of neurodegenerative diseases. The complex interplay between these factors exacerbates neuronal damage and accelerates disease progression. In neurodegenerative diseases, mitochondrial dysfunction impairs ATP production and promotes the generation of reactive oxygen species (ROS). The accumulation of ROS further damages mitochondrial DNA, proteins, and lipids, creating a vicious cycle of oxidative stress and mitochondrial impairment. This review aims to elucidate the mechanisms by which mitochondrial dysfunction and oxidative stress lead to neurodegeneration, and to highlight potential therapeutic targets to mitigate their harmful effects.

Mitochondrial Dysfunction in Neurodegenerative Diseases: Mechanisms and Corresponding Therapeutic Strategies

Neurodegenerative disease (ND) refers to the progressive loss and morphological abnormalities of neurons in the central nervous system (CNS) or peripheral nervous system (PNS). Examples of neurodegenerative diseases include Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). Recent studies have shown that mitochondria play a broad role in cell signaling, immune response, and metabolic regulation. For example, mitochondrial dysfunction is closely associated with the onset and progression of a variety of diseases, including ND, cardiovascular diseases, diabetes, and cancer. The dysfunction of energy metabolism, imbalance of mitochondrial dynamics, or abnormal mitophagy can lead to the imbalance of mitochondrial homeostasis, which can induce pathological reactions such as oxidative stress, apoptosis, and inflammation, damage the nervous system, and participate in the occurrence and development of degenerative nervous system diseases such as AD, PD, and ALS. In this paper, the latest research progress of this subject is detailed. The mechanisms of oxidative stress, mitochondrial homeostasis, and mitophagy-mediated ND are reviewed from the perspectives of β-amyloid (Aβ) accumulation, dopamine neuron damage, and superoxide dismutase 1 (SOD1) mutation. Based on the mechanism research, new ideas and methods for the treatment and prevention of ND are proposed.

2-dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione protects against MPP+-induced neurotoxicity by ameliorating oxidative stress, apoptosis and autophagy in SH-SY5Y cells

2-dodecyl-6-methoxycyclohexa-2,5-diene-1,4-dione (DMDD) is a cyclohexanedione compound extracted from the roots of Averrhoa carambola L. Several studies have documented its beneficial effects on diabetes, Alzheimer's disease, and cancer. However, its potential neuroprotective effects on Parkinson's disease (PD) have not yet been explored. The present study aimed to investigate the protective effects and underlying mechanisms of DMDD in a cellular model of PD. In this study, SH-SY5Y cells were incubated with or without DMDD following intoxication with the parkinsonian neurotoxin 1-methyl-4-phenylpyridine (MPP+). Cell viability and apoptosis were evaluated using 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2 H-tetrazolium (MTS) assay and Hoechst 33,342 staining, respectively. The mitochondrial membrane potential (Δψm) was assessed through the JC-10 assay. The activities of superoxide dismutase (SOD) and the levels of reactive oxygen species (ROS) were measured using WST-8 and DCFH-DA assays. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were performed to explore significant biological processes and pathways influenced by DMDD. Molecular docking was employed to predict the domains of potential protein targets interacting with DMDD. Western blotting was subsequently conducted to determine the protein expression levels of TH, Nrf2, Bax, Bcl-2, Caspase-3, Beclin-1, PARP, LC3-II, LC3-I, p-PI3K, PI3K, p-mTOR and mTOR. Our study showed that DMDD treatment significantly increased cell viability and reduced apoptosis in MPP+-treated SH-SY5Y cells. In addition, DMDD treatment reversed the loss of TH expression and Δψm in MPP+-exposed SH-SY5Y cells. Moreover, DMDD treatment reduced MPP+-induced ROS production by promoting SOD activity. Additionally, compared with those in the MPP+ group, the protein expression levels of Beclin-1, Caspase-3, and PARP and the LC3II/I ratio were significantly decreased, whereas the protein expression levels of Nrf2 and the Bcl-2/Bax, p-PI3K/PI3K, and p-mTOR/mTOR ratios were significantly increased in the DMDD-treated group. In conclusion, DMDD protects against MPP+-induced cytotoxicity by mitigating oxidative stress, apoptosis, and autophagy. PI3K/mTOR signaling at least partly mediates the cytoprotective effect of DMDD.

A Narrative Review: Relationship Between Glycemic Variability and Emerging Complications of Diabetes Mellitus

A growing body of evidence emphasizes the role of glycemic variability (GV) in the development of conventional diabetes-related complications. Furthermore, advancements in diabetes management and increased life expectancy have led to the emergence of new complications, such as cancer, liver disease, fractures, infections, and cognitive dysfunction. GV is considered to exacerbate oxidative stress and inflammation, acting as a major mechanism underlying these complications. However, few reviews have synthesized the association between GV and these emerging complications or examined their underlying mechanisms. Hence, this narrative review provides a comprehensive discussion of the burden, risks, and mechanisms of GV in these complications, offering further evidence supporting GV as a potential therapeutic target for diabetes management.

Mitochondrial microRNAs: Key Drivers in Unraveling Neurodegenerative Diseases

MicroRNAs (miRNAs) are a class of small non-coding RNAs (ncRNAs) crucial for regulating gene expression at the post-transcriptional level. Recent evidence has shown that miRNAs are also found in mitochondria, organelles that produce energy in the cell. These mitochondrial miRNAs, also known as mitomiRs, are essential for regulating mitochondrial function and metabolism. MitomiRs can originate from the nucleus, following traditional miRNA biogenesis pathways, or potentially from mitochondrial DNA, allowing them to directly affect gene expression and cellular energy dynamics within the mitochondrion. While miRNAs have been extensively investigated, the function and involvement of mitomiRs in the development of neurodegenerative disorders like Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis remain to be elucidated. This review aims to discuss findings on the role of mitomiRs in such diseases and their potential as therapeutic targets, as well as to highlight future research directions.

Pharmacodynamic Mechanisms of Cicadae Periostracum in Parkinson's Disease: A Metabolomics-Based Study

Cicadae Periostracum (CP) is a traditional Chinese animal-derived medicine with the potential to treat Parkinson's disease (PD). This study aims to explore the pharmacodynamic mechanisms of CP against PD-based on metabolomics technology and provide a theoretical basis for developing new anti-PD medicine. First, MPP+-induced SH-SY5Y cells were used to evaluate the anti-PD activity of CP. In the animal study, an MPTP-induced PD mouse model was employed to assess CP's therapeutic effects. Immunofluorescence (IF) staining and Western blotting (WB) were used to evaluate its neuroprotective activity on neurons. A Serum metabolomics analysis was conducted to examine CP's regulatory effects on metabolites and to identify vital metabolic pathways. Finally, cellular experiments were performed to validate the critical pathways. Cellular activity experiments demonstrated that CP mitigates MPP+-induced SH-SY5Y cytotoxicity, inhibits apoptosis, and restores mitochondrial homeostasis. Animal experiments revealed that CP significantly alleviates dyskinesia in PD mice, enhances motor performance, and restores neuronal integrity while reducing α-synuclein (α-syn) aggregation in the striatum (STR), showing its strong anti-PD effect. Metabolomic analysis revealed that CP can significantly improve the metabolic disorders of ten biomarkers that are mainly involved in amino acid metabolism and fatty acid β-oxidation and are closely related to oxidative stress pathways. Finally, pathway verification was performed, and the results show that CP exerted neuroprotective effects against PD through the dual signaling pathways of Bcl-2/Bax/Caspase-3 and Nrf2/HO-1. This study provides a comprehensive strategy for elucidating the mechanisms by which CP exerts its therapeutic effects against PD, highlighting its potential in developing anti-PD drugs.

New insights on the regulators and inhibitors of RhoA-ROCK signalling in Parkinson's disease

A multifaceted and widely prevalent neurodegenerative disease, Parkinson's disease (PD) is typified by the loss of dopaminergic neurons in the midbrain. The discovery of novel treatment(s) that can reverse or halt the course of the disease progression along with identifying the most reliable biomarker(s) in PD remains the crucial concern. RhoA in its active state has been demonstrated to interact with three distinct domains located in the central coiled-coil region of ROCK. RhoA appears to activate effectors most frequently by breaking the intramolecular autoinhibitory connections, which releases functional domains from the effector protein. Additionally, RhoA is highly expressed in the nervous system and it acts as a central molecule for its several downstream effector proteins in multiple signalling pathways both in neurons and glial cells. Mitochondrial dysfunction, vesicle transport malfunction and aggregation of α-Synuclein, a presynaptic neuronal protein genetically and neuropathologically associated with PD. While the RhoA-ROCK signalling pathway appears to have a significant role in PD symptoms, suggesting it could be a promising target for therapeutic interventions. Thus, this review article addresses the potential involvement of the RhoA-ROCK signalling system in the pathophysiology of neurodegenerative illnesses, with an emphasis on its biology and function. We also provide an overview of the state of research on RhoA regulation and its downstream biological activities, focusing on the role of RhoA signalling in neurodegenerative illnesses and the potential benefits of RhoA inhibition as a treatment for neurodegeneration.

Trans-sodium crocetinate ameliorates Parkinson-like disease caused by bisphenol A through inhibition of apoptosis and reduction of α-synuclein in rats

Objectives

Trans-sodium crocetinate (TSC) is one of the crocetin derivations that is more soluble and stable than crocetin and its cis form. It easily crosses the blood-brain barrier. TSC has neuroprotective effects. Bisphenol A (BPA) is an endocrine-mimicking compound that induces Parkinson-like disease by impacting the dopaminergic system. In this research, the effects of TSCs on BPA-induced Parkinson-like symptoms via behavioral and molecular assays have been investigated.

Materials and Methods

Male Wistar rats received BPA (75 mg/kg, gavage), TSC (10, 20, and 40 mg/kg), and levodopa (L-dopa) (10 mg/kg) via intraperitoneal injection (IP) for 28 days. Parkinsonian-like motor features were evaluated using bar test, rotarod, and open field experiments. Malondialdehyde (MDA) and glutathione (GSH) levels were also measured as the most important indicators of oxidative stress. Western blotting was performed for the molecular assays of alpha-synuclein (α-syn), Bcl-2, Bax, caspase-3, Beclin, and LC3 I/II proteins.

Results

Our analyses indicated that treatment with TSC at high dose reduces MDA levels and protects GSH reserves. TSC can also increase anti-apoptotic Bcl-2 and decrease pro-apoptotic Bax and caspase-3 proteins. While it does not affect autophagy markers, TSC decreased α-syn protein expression, reduced the catalepsy time, and improved the time spent staying on the rotating bar and the locomotor activity.

Conclusion

Overall, TSC likely ameliorates BPA-mediated Parkinson' s-like symptoms by suppressing oxidative stress inhibition. This leads to reduced α-syn expression, which ultimately results in apoptosis inductions. Therefore, TSC can serve as a promising exploratory target for future research aimed at controlling Parkinson's disease.

Does photobiomodulation alter mitochondrial dynamics?

Mitochondrial dysfunction is one of the leading causes of disease development. Dysfunctional mitochondria limit energy production, increase reactive oxygen species generation, and trigger apoptotic signals. Photobiomodulation is a noninvasive, nonthermal technique involving the application of monochromatic light with low energy density, inducing non-thermal photochemical effects at the cellular level, and it has been used due to its therapeutic potential. This review focuses on the mitochondrial dynamic's role in various diseases, evaluating the possible therapeutic role of low-power lasers (LPL) and light-emitting diodes (LED). Studies increasingly support that mitochondrial dysfunction is correlated with severe neurodegenerative diseases such as Parkinson's, Huntington's, Alzheimer's, and Charcot-Marie-Tooth diseases. Furthermore, a disturbance in mitofusin activity is also associated with metabolic disorders, including obesity and type 2 diabetes. The effects of PBM on mitochondrial dynamics have been observed in cells using a human fibroblast cell line and in vivo models of brain injury, diabetes, spinal cord injury, Alzheimer's disease, and skin injury. Thus, new therapies aiming to improve mitochondrial dynamics are clinically relevant. Several studies have demonstrated that LPL and LED can be important therapies to improve health conditions when there is dysfunction in mitochondrial dynamics.

Roflumilast-loaded nanostructured lipid carriers attenuate oxidative stress and neuroinflammation in Parkinson's disease model

Parkinson's disease (PD) is a progressive neurodegenerative disorder with limited symptomatic treatment options. Targeting phosphodiesterase 4 (PDE4) has shown a promising result in several preclinical studies. In our study, we aim to repurpose US FDA-approved PDE4 inhibitor for PD. Through in-silico study, we identified roflumilast (ROF) as the potential candidate targeting PDE4B2. In Drosophila PD expressing the A30P mutant α-synuclein model, ROF exhibited anti-PD effects as indicated by negative geotaxis and antioxidant activities. Given the low brain distribution of ROF (<50%) at clinical doses, incorporation into nanostructured lipid carriers (NLCs) was carried out to enhanced blood-brain barrier permeability. In vitro release studies indicated sustained ROF release from NLCs (≈75%) over 24 h. Single-dose oral toxicity studies reported no mortality or toxicity signs. ROF-loaded NLCs significantly alleviated behavioural deficits, increased antioxidant parameters (p < 0.05), and reduced TNF-α and IL-6 levels (p < 0.5) in the striatum compared to pure ROF. ROF-loaded NLCs demonstrated potential anti-PD effects with high efficacy than pure ROF. Our study suggests that nanostructured lipid carriers (NLCs) can be a promising drug delivery system to overcome limitations associated with poor brain bioavailability of lipophilic drugs like ROF for PD treatment. Further investigation related to brain occupancy and underlying mechanisms of our formulation is warranted to confirm and strengthen our current findings.

Roles of endoplasmic reticulum stress and activating transcription factors in Alzheimer's disease and Parkinson's disease

Endoplasmic reticulum (ER) is a crucial organelle associated with cellular homeostasis. Accumulation of improperly folded proteins results in ER stress, accompanied by the reaction involving triggering unfolded protein response (UPR). The UPR is mediated through ER membrane-associated sensors, such as protein kinase-like ER kinase (PERK), inositol-requiring transmembrane kinase/endoribonuclease 1α, and activating transcription factor 6 (ATF6). Prolonged stress triggers cell apoptotic reaction, resulting in cell death. Neuronal cells are especially susceptible to protein misfolding. Notably, ER and UPR malfunctions are linked to many neurodegenerative diseases, such as Alzheimer's disease (AD) and Parkinson's disease (PD), delineated by accumulation of misfolded proteins. Notably, ATF family members play key roles in AD and PD pathogenesis. However, the connection between ER stress, UPR, and neuropathology is not yet fully understood. Here, we discuss our present knowledge of the association between ER stress, the UPR, and neurodegeneration in AD and PD. We also discuss the roles of ATF family members in AD and PD pathogenesis. Moreover, we provide a mechanistic clarification of how disease-related molecules affect ER protein homeostasis and explore recent findings that connect the UPR to neuronal plasticity.

Oxidative stress and inflammation in the pathogenesis of neurological disorders: Mechanisms and implications

Neuroprotection is a proactive approach to safeguarding the nervous system, including the brain, spinal cord, and peripheral nerves, by preventing or limiting damage to nerve cells and other components. It primarily defends the central nervous system against injury from acute and progressive neurodegenerative disorders. Oxidative stress, an imbalance between the body's natural defense mechanisms and the generation of reactive oxygen species, is crucial in developing neurological disorders. Due to its high metabolic rate and oxygen consumption, the brain is particularly vulnerable to oxidative stress. Excessive ROS damages the essential biomolecules, leading to cellular malfunction and neurodegeneration. Several neurological disorders, including Alzheimer's, Parkinson's, Amyotrophic lateral sclerosis, multiple sclerosis, and ischemic stroke, are associated with oxidative stress. Understanding the impact of oxidative stress in these conditions is crucial for developing new treatment methods. Researchers are exploring using antioxidants and other molecules to mitigate oxidative stress, aiming to prevent or slow down the progression of brain diseases. By understanding the intricate interplay between oxidative stress and neurological disorders, scientists hope to pave the way for innovative therapeutic and preventive approaches, ultimately improving individuals' living standards.

ATAD1 Regulates Neuronal Development and Synapse Formation Through Tuning Mitochondrial Function

Mitochondrial function is essential for synaptic function. ATAD1, an AAA+ protease involved in mitochondrial quality control, governs fission-fusion dynamics within the organelle. However, the distribution and functional role of ATAD1 in neurons remain poorly understood. In this study, we demonstrate that ATAD1 is primarily localized to mitochondria in dendrites and, to a lesser extent, in spines in cultured hippocampal neurons. We found that ATAD1 deficiency disrupts the mitochondrial fission-fusion balance, resulting in mitochondrial fragmentation. This deficiency also impairs dendritic branching, hinders dendritic spine maturation, and reduces glutamatergic synaptic transmission in hippocampal neuron. To further investigate the underlying mechanism, we employed an ATP hydrolysis-deficient mutant of ATAD1 to rescue the neuronal deficits associated with ATAD1 loss. We discovered that the synaptic deficits are independent of the mitochondrial morphology changes but rely on its ATP hydrolysis. Furthermore, we show that ATAD1 loss leads to impaired mitochondrial function, including decreased ATP production, impaired membrane potential, and elevated oxidative stress. In conclusion, our results provide evidence that ATAD1 is crucial for maintaining mitochondrial function and regulating neurodevelopment and synaptic function.

The therapeutic potential of glycyrrhizic acid and its metabolites in neurodegenerative diseases: Evidence from animal models

Neurodegenerative diseases, mostly occurring in the elderly population, are the significant cause of disability and death worldwide. The pathogenesis of neurodegenerative diseases is still largely unknown yet, although they have been continuously explored. Thus, there is still a lack of safe, effective, and low side effect drugs in clinical practice for the treatment of neurodegenerative diseases. Pieces of accumulating evidence have demonstrated that licorice played neuroprotective roles in various neurodegenerative diseases. In the past two decades, increasing studies have indicated that glycyrrhizic acid (GL), the main active ingredient from traditional Chinese medicine licorice (widely used in the food industry) and a triterpenoid saponin with multiple pharmacological effects (such as anti-oxidant, anti-inflammatory, and immune regulation), and its metabolites (glycyrrhetinic acid and carbenoxolone) play a neuroprotective role in a range of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Huntington's disease and epilepsy. This review will elaborate on the multiple neuroprotective mechanisms of GL and its metabolites in this series of diseases, aiming to provide a basis for further research on these protective drugs for neurodegenerative diseases and their clinical application. In summary, GL may be a promising candidate drug for the therapy of neurodegenerative diseases.