Search Results (292)

Impairment of axonal transport may contribute to the degeneration of dopaminergic (DAergic) neurons in the substantia nigra (SN), a key event in Parkinson’s disease (PD) pathogenesis. Due to the lack of early diagnosis, changes in axonal transport at the preclinical stage can only be studied in PD models. We assessed gene expression (RT-PCR after cell sorting) and protein levels (semiquantitative immunohistochemistry) of axonal transport-related proteins in SN DAergic neurons from mice in subchronic MPTP models of PD (preclinical and clinical stages) and controls. The proteins studied included α-tubulin (Tuba1a), β-tubulin (Tubb3), kinesin (Kif5b, Klc1), dynein (Dynll1, Dync1i1), dynactin (Dctn1), microtubule affinity-regulating kinase 1 (Mark1), and tau (Mapt). In the preclinical stage, Kif5b expression and Kif5B level were increased, possibly to compensatorily preserve anterograde transport. Dynll1 and Tuba1a were upregulated, whereas Dync1i1 and Mapt were downregulated, with no change in tubulin or tau protein levels. In the clinical stage, Klc1, Dync1i1, Dctn1, Mark1, and Mapt expression and Kif5B protein levels decreased. These data indicate that transcriptional alterations in axonal transport proteins precede protein-level changes in DAergic neurons. The upregulation of Kif5B in the preclinical stage suggests that axonal transport proteins may serve as potential early therapeutic targets in PD. Full article

Parkinson’s disease (PD) is characterized by progressive nigrostriatal degeneration and striatal dysfunction, yet its metabolic remodeling remains incompletely defined. Here, untargeted GC–MS metabolomics was used to investigate the effects of standardized Brazilian green propolis on the striatal metabolic profile in the 6-hydroxydopamine (6-OHDA) rat model. Discriminant metabolites, including suberic acid, gluconic acid, heptadecane, and tartaric acid, distinguished experimental groups, capturing key features of the metabolic response to dopaminergic injury and treatment. Suberic acid emerged as a prominently modulated metabolite, potentially linked to alterations in lipid catabolism associated with mitochondrial–peroxisomal pathways. Propolis treatment attenuated the elevation of suberic acid, accompanied by a reduction in gluconic acid levels, suggesting a metabolic profile linked to pathways involved in redox balance and glucose handling. Given previous reports identifying heptadecane as a hydrocarbon constituent of volatile propolis fractions, complementary GC-Q-TOF analyses demonstrated that heptadecane was absent from the administered extract, despite its consistent association with propolis-treated groups. Metabolic changes were accompanied by attenuation of nigrostriatal dopaminergic neurodegeneration and improved motor performance. Together, these findings delineate a striatal metabolic signature associated with Brazilian green propolis and identify suberic acid as a key metabolite linked to neuroprotection in experimental Parkinsonism. Full article

Parkinson’s disease (PD) is a neurodegenerative disorder characterized by the aggregation of Lewy bodies, composed of the protein α-synuclein, and the degeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta. The management of PD seeks to mitigate motor symptoms by substituting diminished endogenous dopamine; nevertheless, it does not halt disease progression. Various animal models have been employed to elucidate the etiology of PD and to discover disease-modifying treatments. Zebrafish serve as a PD model owing to their capacity for high-throughput screening. This review presents updates on the currently available zebrafish models of PD, encompassing both chemically induced and genetically based models, and discusses their advantages and limitations. This review also delineates numerous investigative strategies that utilize the zebrafish PD model and summarizes the findings of previous studies. Taken together, further studies, including the investigation of the regeneration mechanism of DA neurons, neurobehavioral testing of adult zebrafish reflecting PD-associated neurocognitive impairment, and a reliable gene-based model providing precise gene knockout and reproducibility, may assist in elucidating the critical pathways that trigger PD and its progression, alongside potential targets to hinder this progression. Full article

Parkinson’s disease (PD) is a neurodegenerative disorder of the central nervous system with a complex pathogenesis. Current conventional medicines are predominantly symptomatic treatments, which fail to reverse neuronal degeneration and often induce severe motor complications following long-term administration. In this context, the advantages of the multi-target holistic regulation provided by traditional Chinese medicine have become increasingly prominent. As the core active ingredients of Panax ginseng, ginsenosides can penetrate the blood–brain barrier and exhibit broad neuroprotective prospects in PD treatment. This article systematically reviews the neuroprotective mechanisms of different configurations of ginsenosides—mainly including protopanaxadiol (PPD) and protopanaxatriol (PPT) saponins—against PD. Studies indicate that PPD-type saponins (e.g., Rb1, Rg3, Rd) excel in directly inhibiting the abnormal aggregation of α-synuclein (α-syn), reducing oxidative stress, and preventing neuronal apoptosis. Conversely, PPT-type saponins (e.g., Rg1, Re) demonstrate significant advantages in suppressing microglia-mediated neuroinflammation, improving mitophagy, and regulating lipid metabolism networks. Furthermore, this review highlights a novel intervention strategy utilizing ginsenosides based on antioxidation and iron metabolism regulation. By maintaining the homeostasis of iron transport proteins such as DMT1 (Divalent Metal Transporter 1) and FPN1 (Ferroportin 1), and activating the Nrf2/xCT/GPX4 signaling axis, these compounds effectively block the vicious cycle of “iron deposition-oxidative stress-lipid peroxidation (LPO),” thereby inhibiting ferroptosis in dopaminergic neurons. In summary, structurally diverse ginsenosides exhibit distinct characteristics in targeting the core pathological events of PD. The scientific combination of ginsenoside monomers with different mechanisms in the future holds promise for constructing a comprehensive multi-target neuroprotective network, providing a solid theoretical foundation for novel ginsenoside-based combination therapies against PD. Full article

The relationship between stress and Parkinson’s disease is regarded as complex and multifaceted, although a direct causal link has not yet been conclusively proven. One prevailing hypothesis is based on the activation of the hypothalamic–pituitary–adrenal (HPA) axis and the consequent elevation of glucocorticoid levels. Prolonged exposure to these hormones may exacerbate oxidative stress, thereby rendering the dopaminergic neurons within the brain’s subcortical structures more susceptible to degeneration. Furthermore, stress may intensify neuroinflammation through the activation of microglia—a mechanism that could constitute a significant factor in the pathogenesis of Parkinson’s disease. Another important concept concerns the direct interaction of stressors with the dopaminergic system. Physiological and psychological stress can alter dopaminergic transmission by affecting both the synthesis and release of dopamine, as well as the sensitivity of dopamine receptors. Severe or chronic stress may contribute to the disruption of dopaminergic mechanisms and accelerate the onset of clinical symptoms in predisposed individuals. Furthermore, many researchers draw attention to the role of stress-induced aggregation of α-synuclein—a key protein implicated in the pathogenesis of Parkinson’s disease. Clinical data suggest a highly probable link between post-traumatic stress disorder and an increased risk of developing Parkinson’s disease, although these findings remain inconclusive. It is possible that stress acts not as a primary cause, but rather as a modifying factor that interacts with genetic predisposition, accelerating or triggering neurodegenerative processes. The aim of our narrative review was to examine these concepts and discuss possible directions for future research into the interaction between stress and Parkinson’s disease. Full article

Background/Objectives: Imaging of both cardiac sympathetic denervation and nigrostriatal dopaminergic degeneration can support the diagnosis of Parkinson’s disease (PD). However, their temporal relationship and combined diagnostic value remain unclear. This review addresses (1) whether nigrostriatal degeneration and cardiac sympathetic denervation are correlated in PD and (2) the comparative and combined diagnostic accuracy of striatal dopaminergic and cardiac sympathetic imaging in PD. Methods: We searched PubMed (October 2025) for studies assessing both a striatal dopaminergic and a cardiac sympathetic imaging biomarker in the same PD cohort, supplemented by citation chaining. Diagnostic accuracy studies were evaluated using QUADAS-2. Results: Nineteen studies met the inclusion criteria. Ten studies examined within-subject associations; six reported significant correlations ranging from weak to strong (ρ ~0.2–0.8). Two studies observed a significant correlation for the akinetic-rigid subtype but not for the tremor-dominant subtype of PD. Ten studies compared diagnostic accuracies, five of which used pre-defined thresholds and consistently found higher sensitivity for [¹²³I]FP-CIT SPECT (78–100%) compared to [¹²³I]MIBG scintigraphy (65–82%), but higher specificity for [¹²³I]MIBG (range 75–100%) than for [¹²³I]FP-CIT (range 11–73%). Adding [¹²³I]MIBG scintigraphy to [¹²³I]FP-CIT SPECT generally increased specificity but had inconsistent effects on overall accuracy. QUADAS-2 revealed substantial risks of patient selection bias, data-driven thresholds, and limited blinding. Conclusions: Reported correlations between nigrostriatal dopaminergic degeneration and cardiac sympathetic denervation in PD are inconsistent, likely reflecting both methodological heterogeneity and real variation between phenotypes. There may be a stronger correlation in the akinetic-rigid phenotype. Dopaminergic imaging is more sensitive in early PD, while cardiac sympathetic imaging is more specific for differentiating PD from atypical Parkinsonian syndromes. However, study designs greatly restrict the generalizability of reported diagnostic accuracies. Full article

Progressive supranuclear palsy-Richardson’s syndrome (PSP-RS) is a primary 4R tauopathy in which early axonal dysfunction may precede overt neurodegeneration; however, the mechanisms linking Tau dysregulation to cytoskeletal vulnerability remain poorly defined. Here, we generated induced pluripotent stem cell (iPSC)-derived midbrain dopaminergic neurons from individuals with sporadic PSP-RS and matched healthy controls and performed integrated transcriptomic and proteomic analyses. PSP-RS neurons exhibited coordinated suppression of dopaminergic and synaptic programs alongside activation of cytoskeletal remodeling and stress-related pathways. These changes were accompanied by increased Tau phosphorylation, neurofilament accumulation, and structural alterations of the axonal compartment, consistent with an early axonopathic phenotype. Notably, mechanistic target of rapamycin (mTOR) signaling significantly increased. Pharmacological inhibition of mTOR reduced Tau phosphorylation and neurofilament levels, indicating that mTOR activity contributes to the maintenance of cytoskeletal imbalance. In conclusion, our findings support a model in which early cytoskeletal dysfunction in PSP-RS arises from the convergence of Tau dysregulation, impaired structural homeostasis, and altered signaling pathways. Rather than acting as a primary driver, mTOR appears to function as a pathogenic amplifier that sustains axonal stress. This study provides a human cellular framework to investigate early axonopathic mechanisms in sporadic PSP-RS. Full article

Neurovascular coupling (NVC) maintains appropriate cerebral blood flow (CBF) in response to neuronal activity, and its disturbance, known as neurovascular uncoupling (NVU), is increasingly recognised as a major contributor to neurodegenerative disease. Alzheimer’s disease (AD) NVU is caused by Aβ buildup, tau pathology, endothelial dysfunction, and persistent neuroinflammation, leading to poor CBF control and blood–brain barrier (BBB) disintegration. Parkinson’s disease (PD) is characterised by α-synuclein aggregation, oxidative stress, mitochondrial dysfunction, and dopaminergic neuronal loss, all of which impede cerebrovascular regulation. These disease-specific mechanisms interact via similar vascular pathways, establishing NVU as a critical connection between neuronal degeneration and cerebrovascular dysfunction. This study highlights the critical role of NVU in neurodegeneration by investigating shared and disease-specific processes in AD and PD. Tau pathology disturbs vascular regulation in AD, whereas dopaminergic neuron loss impairs cerebrovascular control in PD. Both Aβ and α-synuclein are linked to endothelial dysfunction and oxidative stress, albeit originating in different pathologies. Comparative analysis reveals distinct vascular abnormalities in each condition, as well as shared processes such as inflammation and BBB disruption. The study also covers developments in biomarker discovery and neuroimaging techniques that allow for exact characterisation of NVU, facilitating early diagnosis and treatments. In addition, lifestyle changes and pharmacological treatments for oxidative stress and endothelial injury are being examined. This study highlights the significance of NVU as a fundamental pathogenic mechanism, underscoring its importance for comprehending disease development and formulating novel therapeutic strategies. Full article

Background and Objectives: Parkinson’s disease (PD) entails the progressive degeneration of dopaminergic neurons in the substantia nigra (SN), accompanied by α-synuclein (α-syn)-enriched Lewy bodies. ITGA7 mediates cell–extracellular matrix adhesion and modulates apoptosis, though its involvement in PD pathogenesis warrants further investigation. Although acupuncture demonstrates neuroprotective effects in PD models, its precise molecular mechanisms remain incompletely understood; therefore, in this study, we explored the relationship between ITGA7 and α-synuclein expression in an MPTP-induced PD mouse model to determine the association between LR3/GB34 acupuncture-induced changes in α-synuclein levels and ITGA7 modulation. Materials and Methods: In the in vivo model, MPTP-induced PD mice underwent immunohistochemistry, immunofluorescence, and Western blotting to assess ITGA7, α-synuclein, and TH levels in the SN and striatal tissues following LR3/GB34 acupuncture. In parallel, for the in vitro mechanistic study, SH-SY5Y neuroblastoma cells treated with MPP⁺ and transfected with ITGA7-siRNA were utilized to examine the involvement of apoptosis-related signaling pathways. Results: In the in vivo model, MPTP administration downregulated ITGA7 and upregulated α-synuclein in SN tissues. Similarly, in vitro exposure of SH-SY5Y cells to MPP⁺ yielded comparable results, revealing an inverse correlation between ITGA7 and α-synuclein. LR3/GB34 acupuncture treatment in the mouse model significantly increased ITGA7 and TH expression while reducing α-synuclein accumulation. To further understand the specific role of ITGA7 observed in these animal findings, we silenced ITGA7 in the MPP⁺-treated cellular model. ITGA7 silencing exacerbated the neurotoxic effects, leading to further TH downregulation, α-synuclein upregulation, Bcl-2 reduction, and Bax/Bcl-2 ratio elevation. Conclusions: Collectively, the histological preservation of dopaminergic neurons following LR3/GB34 acupuncture in the PD mouse model appears to be linked to ITGA7 upregulation. Furthermore, our in vitro findings implicate ITGA7 in the regulation of apoptosis-related signaling cascades, supporting its potential role in mitigating α-synuclein pathology. Full article

Background: Parkinson’s disease (PD) is characterized by progressive degeneration of dopaminergic neurons in the substantia nigra pars compacta, accompanied by neuromelanin loss. Neuromelanin-sensitive magnetic resonance imaging (NM-MRI) enables in vivo visualization of these changes; however, its diagnostic and clinical utility remains incompletely defined. This study evaluated the feasibility, reliability, and biological sensitivity of semi-automated NM-MRI–based substantia nigra volumetry in PD. Methods: In this prospective case–control study, 50 participants (25 PD patients and 25 healthy controls) underwent 3T NM-sensitive MRI using a high-resolution T1-weighted spin-echo sequence. Semi-automated segmentation of hyperintense substantia nigra regions was performed using Mango v3.5.1, with intracranial volume normalization derived from FreeSurfer v7.3. Four participants were excluded due to motion artifacts, yielding a final cohort of 46 subjects. Clinical assessment included the Unified Parkinson’s Disease Rating Scale (UPDRS) Part III and Hoehn and Yahr (H&Y) staging. Group comparisons, receiver operating characteristic (ROC) analysis, and reliability testing using intraclass correlation coefficients (ICC) were performed. Results: Corrected substantia nigra volume was significantly reduced in PD patients compared with controls (18% reduction; p = 0.039, Mann–Whitney U test). Semi-automated measurements demonstrated excellent agreement with manual segmentation (ICC = 0.945). ROC analysis showed moderate discriminative performance for corrected volume (AUC = 0.700; sensitivity 68.4%, specificity 74.1%). No significant correlation was observed between corrected substantia nigra volume and UPDRS-III motor scores, while a trend toward lower SNc volume was observed with advancing H&Y stage. Conclusions: Semi-automated NM-MRI volumetry detects biologically meaningful substantia nigra volume loss in early-stage Parkinson’s disease with high measurement reliability. However, diagnostic performance was moderate and insufficient for standalone clinical diagnosis or motor severity prediction. These findings support the role of NM-MRI as a complementary imaging marker within multimodal diagnostic and research frameworks rather than as an independent diagnostic tool. Full article

Dopaminergic neurodegeneration is a hallmark of Parkinson’s disease (PD), and environmental contaminants have been implicated in disrupting dopaminergic pathways. However, practical in vivo workflows for rapid, standardized, and accessible assessment of dopaminergic neurotoxicity remain limited. In this study, we built on our laboratory’s established high-throughput framework and implemented a high-content imaging workflow to quantify DA neurodegeneration in Caenorhabditis elegans following exposure to representative per- and polyfluoroalkyl substances (PFAS). We evaluated the neurotoxic effects of perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonic acid (PFHxS), perfluorohexanoic acid (PFHxA), and three PFAS mixtures with environmentally relevant component ratios. Functional relevance was assessed using dopamine-dependent behavioral endpoints, including basal slowing response (BSR) and area-restricted search (ARS). PFOS exhibited the greatest potency, followed by PFHxS, PFHxA, and PFOA, based on morphological degeneration and benchmark concentration modeling. Structural neuronal damage was significantly associated with behavioral impairment. Under mixture conditions, neurotoxicity was more strongly associated with PFOS molar fraction than with total PFAS concentration (ΣPFAS), suggesting a composition-dependent toxicity profile. Collectively, these findings establish a scalable in vivo framework for assessing PFAS-induced dopaminergic neurotoxicity and support the potential use of this platform for screening environmental pollutants with dopaminergic neurotoxic potential. Full article

Parkinson’s disease (PD) is characterized by the progressive degeneration of dopaminergic neurons and the accumulation of α-synuclein-rich inclusions, largely resulting from impaired protein clearance mechanisms. Copper is an essential redox-active metal in the central nervous system (CNS), but alterations in its homeostasis can promote oxidative stress, mitochondrial dysfunction, and proteostatic failure. In vitro studies indicate that copper can promote α-synuclein misfolding, enhance oxidative stress, and interfere with both the ubiquitin–proteasome system (UPS) and the autophagy–lysosome pathway (ALP). In this review, we critically evaluate mechanistic evidence from cellular models, integrating available animal and clinical data to assess the biological significance of copper-mediated impairment of α-synuclein clearance. We highlight the current research, identify methodological limitations, and discuss whether copper imbalance acts as a primary pathogenic trigger or as a disease-modifying amplifier of proteostatic failure. Furthermore, we consider the translational implications of selectively modulating intracellular copper pools as a therapeutic strategy in PD. Finally, we will highlight unresolved issues, methodological limitations, and emerging targeted therapeutic prospects. Full article

Alzheimer’s disease (AD), the leading cause of global dementia, is a multifactorial process that goes beyond the accumulation of β-amyloid (Aβ) plaques and tau protein tangles, including glia cell-mediated neuroinflammation, vascular dysfunction, metabolic alterations, and synaptic loss. Its complex etiology also involves oxidative stress and mitochondrial dysfunction. Multiple neurotransmitter systems involved in the pathogenesis and the various cognitive and non-cognitive symptoms of AD are thus altered. The cholinergic system, historically the first to be associated with AD, suffers early degeneration and loss of neurons/receptors, correlating with cognitive impairment. The glutamatergic system, the main excitatory system, exhibits excitotoxicity due to increased extracellular glutamate and alterations in NMDA/AMPA receptor distribution, exacerbating neuronal damage. The GABAergic system, the main inhibitor, shows alterations in parvalbumin-positive interneurons, leading to hyperexcitability and dysfunction of neuronal networks. Monoaminergic systems (serotonergic, dopaminergic and noradrenergic) undergo early degeneration in key nuclei such as the raphe and locus coeruleus, contributing to the apathy, depression and sleep disturbances characteristic of AD. Other less explored systems, such as histaminergic and purinergic, are also crucial in cognitive modulation and neuroinflammation. The endocannabinoid system acts as a master modulator with neuroprotective and anti-inflammatory effects. These systems do not operate in isolation; their complex interactions generate pathological circuits that amplify neuronal dysfunction. The limited efficacy of current therapies, which are primarily symptomatic, highlights the need for multimodal approaches that may transform AD treatment toward personalized and more effective interventions. Full article

Background: Chronic cocaine exposure is increasingly associated with persistent brain alterations, yet it remains unclear whether these changes reflect reversible neuroadaptation, accelerated brain ageing, or a degeneration-like trajectory in a vulnerable subgroup. This Perspective proposes a neuroprogressive vulnerability framework—referred to as cocaine-specific encephalopathy/cerebropathy only in a heuristic sense—to organise heterogeneous evidence without implying a distinct neurodegenerative disease entity. Methods: We conducted a structured, critical synthesis of peer-reviewed human and preclinical literature (PubMed, Scopus, Web of Science; inception to December 2025), integrating neuroimaging (MRI/DTI/fMRI/PET/SPECT), neuropathology/post-mortem findings, neurochemical and molecular mechanisms, and neuropsychological outcomes, with explicit attention to confounders (polysubstance use, psychiatric and medical comorbidity, HIV, vascular risk, abstinence duration). Results: Convergent evidence supports a multi-hit vulnerability model in which chronic stimulant exposure may weaken neural resilience through dopaminergic dysregulation, oxidative stress, mitochondrial dysfunction, neuroinflammatory signalling, and putative α-synuclein–related mechanisms. Human imaging studies consistently implicate fronto–striato–limbic circuits and suggest possible cerebellar involvement, but findings are heterogeneous and often cross-sectional; direct evidence of progressive neuronal loss or disease-defining proteinopathies attributable to cocaine remains limited. Conclusions: Rather than asserting cocaine-induced classic neurodegeneration, we outline an exploratory framework in which chronic cocaine exposure may increase susceptibility to neuroprogressive impairment in a subset of biologically vulnerable individuals. Longitudinal multimodal studies combining advanced imaging, biomarkers, and phenotypic stratification are needed to clarify causality, temporal progression, and reversibility with sustained abstinence. Full article

The pathogenesis of Parkinson’s disease (PD) is characterized by progressive degeneration of nigrostriatal dopaminergic signaling, resulting in motor dysfunction. Although monoamine oxidase (MAO) inhibitors are clinically used in PD, their long-term efficacy and safety remain limited. In the present study, three novel N-benzylpyrrolidine derivatives (3e, 3f, and 3i), previously identified as dual MAO-A/B inhibitors in silico and in vitro, were pharmacologically evaluated in an acute 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of PD. The compounds were administered intraperitoneally starting 2 days prior to MPTP exposure and continuing for 6 days thereafter. Repeated administration of the compounds did not alter striatal dopamine (DA) levels under basal conditions, indicating no detectable modulation of dopaminergic tone in vivo. All three derivatives ameliorated MPTP-induced motor deficits. Compounds 3f and 3i improved motor function without detectable changes in striatal DA levels, whereas compound 3e partially restored striatal DA levels, similar to the positive control. In addition, compound-specific alterations in hippocampal pro-inflammatory cytokines were observed, including increased levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) following 3e administration. Together, these findings provide in vivo pharmacological characterization of novel MAO-targeting derivatives and reveal differential behavioral, neurochemical, and cytokine profiles among the tested compounds, supporting further mechanistic investigation. Full article