Search Results (362)

The circadian rhythm is an internal timing system formed by the body’s adaptation to the Earth’s rotation, which helps maintain homeostasis by regulating physiological, metabolic, and behavioral activities. The gut microbiota (GM), the largest microbial ecosystem in the human body, exhibits a bidirectional regulatory relationship with the host circadian clock. Emerging evidence indicates that circadian rhythm disruption (CRD) is linked to disturbances in the diurnal oscillations and compositional balance of the GM, accompanied by reduced short-chain fatty acid levels, increased lipopolysaccharide leakage, and altered tryptophan metabolism. These microbial abnormalities may be involved in anxiety-like behaviors through three major pathways: neuroendocrine (hyperactivation of the HPA axis), immune (microglia-mediated neuroinflammation), and neurotransmitter (imbalance of the serotonergic and dopaminergic systems). Conversely, microbial metabolites such as butyrate and secondary bile acids may reciprocally regulate peripheral clock gene expression, forming a complex “circadian rhythm–GM–anxiety” interaction network. This review summarizes the molecular basis of circadian–GM interactions, potential GM-mediated mechanisms linking CRD with anxiety, and emerging intervention strategies including chrononutrition (time-restricted feeding, sequential nutrient intake), microbiota-targeted therapies (probiotics/prebiotics, fecal microbiota transplantation), and light therapy and melatonin supplementation. Future directions should focus on cell-specific mechanisms using single-cell and spatial transcriptomics, developing personalized interventions that integrate chronotype and microbiome profiling, and conducting large-scale randomized controlled trials to facilitate clinical translation. This review provides a framework for understanding the integrative role of circadian biology and gut microbiota in anxiety and may help develop precision intervention paradigms. Full article

Background/Objectives. Parkinson’s disease (PD) is a multifactorial neurodegenerative disorder characterized by dopaminergic neuron loss, α-synuclein pathology, neuroinflammation, and cognitive decline. Synaptamide (N-Docosahexaenoylethanolamine (DHEA)) is an endogenous lipid mediator with documented anti-inflammatory and neurogenic properties, but its effects in PD models remain unexplored. This study aimed to evaluate the neuroprotective potential of synaptamide in a subchronic MPTP-induced mouse model of PD. Methods. Male C57BL/6 mice received MPTP (30 mg/kg/day, i.p., 5 days) with or without synaptamide (10 mg/kg/day, s.c., 13 days). Behavioral tests (open field, Y-maze, elevated plus maze, novel object recognition (NOR)) were performed, followed by immunohistochemical analysis of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra, and Western blotting for α-synuclein, p-α-synuclein, TH, and IL1β in brain homogenates and serum. In vitro Neuro-2a cells were co-treated with MPP⁺ (100 µM) and synaptamide (0.1–10 µM) for cytotoxicity assessment (MTS assay). Results. Synaptamide (10 µM) significantly attenuated MPP⁺-induced cytotoxicity in Neuro-2a cells. In vivo, MPTP caused a marked loss of TH⁺-neurons in the substantia nigra, which was prevented by synaptamide treatment. Importantly, this subchronic MPTP model recapitulates early biochemical alterations (e.g., α-synuclein phosphorylation at Ser129) rather than mature Lewy body pathology, a limitation that should be considered when interpreting these findings. Although no motor deficits or anxiety-like behavior were observed, the NOR test revealed MPTP-induced long-term memory impairment, which was fully restored by synaptamide. Conclusions. These findings suggest that synaptamide may exert effects on pathological processes associated with PD, warranting further investigation into its potential role in combination or supportive therapy for this disease. Full article

Approximately 30% of patients with tremor-dominant Parkinson’s disease (PD) have rest tremor that persists despite optimal dopaminergic therapy. When deep brain stimulation and focused ultrasound are unavailable or declined, the therapeutic options narrow. Botulinum toxin (BoNT) offers a targeted, titratable, reversible approach, but whether a peripheral neuromuscular blocking agent makes sense for a centrally generated tremor is a legitimate question that deserves a direct answer. This narrative critical review appraises what is currently known across PD and non-PD tremor conditions, defines the technical requirements for safe and effective injection, and provides a practical framework for patient selection and clinical management. The PD-specific literature rests on a single positive double-blind randomized controlled trial of 30 patients; all remaining data are open-label or extrapolated from other tremor conditions, and this narrative synthesis combines heterogeneous conditions, outcome scales, and toxin protocols. A recurring technical observation is that, in the available trials, individualized, EMG-guided injection has been associated with substantially lower rates of hand weakness than fixed-dose injection (reported reductions from roughly 30–70% to below 15%) while maintaining tremor reduction, although the degree of benefit and weakness risk vary with the tremor syndrome, injected muscles, baseline impairment, dose, and guidance method. The careful patient selection this approach requires helps the individual clinician and patient achieve tremor relief, but it departs from the unselected real-world PD population and introduces selection bias that makes a large, statistically representative cohort difficult to assemble. In well-selected patients at centers with the appropriate expertise, BoNT may be a clinically useful option, but routine adoption is not yet supported. Full article

We analyze data indicating that a set of currently marketed FDA/EMA-approved drugs used to treat parkinsonism, extrapyramidal side effects of antipsychotic drugs, or overactive bladder may have the potential to slow the growth of glioblastoma; diffuse midline glioma, H3K27-altered (DMG); and a particular form of DMG growing in the pons of children, diffuse intrinsic pontine glioma (DIPG). These gliomas are typically associated with poor prognosis. Clinical trials evaluating conventional chemotherapeutic drugs have failed to improve DIPG survival. Our analysis of the biochemistry and physiology of DMG and DIPG concludes that neuronal acetylcholinergic agonisms at muscarinic receptors M1 and M3 on primitive oligodendrocyte precursor cells (OPCs) are trophic, growth-stimulating factors in DMG/DIPG growth. A set of muscarinic receptor inhibitors—benztropine, biperiden, and trihexyphenidyl—is used clinically to treat Parkinson’s disease or the parkinsonian side effects from antipsychotic medicines. Another muscarinic inhibitor, oxybutynin, is used to treat overactive bladder. All four drugs may impose dose-related side effects inherent to muscarinic receptor inhibition, such as xerostomia, asthenia, and mild cognitive impairment. We recount the evidence for the inhibition of OPC proliferation and migration mediated by these four M1/M3 inhibitors and report details on the rationale for selecting oxybutynin as the primary candidate for adjuvant therapy in DMG/DIPG. We chose oxybutynin as the first choice to study in DMG and DIPG compared to other antimuscarinic drugs based on its (i) high brain-tissue concentration, (ii) relatively stronger M3 inhibition, (iii) lower side-effect propensity than scopolamine, (iv) wide availability, and (v) the absence of H1 antihistamine or dopaminergic effects. Given the rapidly fatal nature of DMG and DIPG, the potential of oxybutynin for growth slowing may outweigh the associated risks and mild side-effect burdens. Full article

The dopamine D₃ receptor (D₃R) has long been considered a secondary target in the treatment of Parkinson’s disease (PD), with therapeutic strategies primarily focused on D₂ receptor–mediated motor control. However, accumulating evidence now supports D₃R as a functionally distinct dopaminergic receptor subtype with specific relevance to non-motor symptom domains and dopaminergic signaling under hypodopaminergic conditions. Recent advances in high-resolution structural biology have elucidated the molecular basis of D₃R/D₂R discrimination, revealing how subtle residue-level and microstructural differences within a conserved G protein–coupled receptor framework shape ligand recognition and receptor activation. In parallel, the emergence of ligand-dependent biased signaling has refined current understanding of D₃R pharmacology. Selected ligands can preferentially engage Gα_i/o-mediated pathways while limiting β-arrestin recruitment and associated regulatory processes, providing a mechanistic rationale for more stable modulation of mesolimbic dopaminergic circuits involved in affective and motivational regulation. Beyond symptomatic modulation, preclinical studies suggest that D₃R signaling may influence neuronal resilience, synaptic plasticity, and adaptive responses to dopaminergic injury; however, such effects remain experimental and have not been demonstrated in clinical PD. This review integrates recent structural, signaling, and functional insights into D₃R biology, with particular emphasis on biased agonism and emerging therapeutic concepts. Although D₃R-targeted strategies do not currently represent disease-modifying interventions, they offer a rational framework for the development of next-generation dopaminergic therapies aimed at improving precision, tolerability, and long-term signaling stability in Parkinson’s disease. Full article

Cell replacement therapy is a promising investigational approach for Parkinson’s disease (PD), a neurodegenerative disorder characterized by progressive loss of dopaminergic neurons in the substantia nigra. Although current PD therapies provide symptomatic relief, none halt or reverse disease progression. Early transplantation studies using fetal dopaminergic neurons provided proof of concept for PD cell replacement, with recent efforts focusing on pluripotent stem cell-derived dopaminergic progenitors that are now entering clinical testing. These strategies face challenges, however, including immune compatibility, tumorigenic risk, and the need for controlled differentiation and functional integration. Multi-lineage differentiating stress-enduring (Muse) cells are endogenous, non-tumorigenic pluripotent-like stem cells that home to sites of tissue injury and differentiate in response to the host microenvironment. A targeted literature search of PubMed and Scopus, however, did not identify prior reviews specifically addressing Muse cells in the context of PD, highlighting a gap in the literature. Here, we examine current limitations of established cell-replacement approaches and consider whether Muse cells may represent a mechanistically distinct cell source. Early clinical studies of Muse cell therapy in stroke and amyotrophic lateral sclerosis suggest an encouraging safety profile and preliminary signals of potential therapeutic benefit, although these findings are based on small, early-stage trials and require confirmation. The evidence supporting Muse cell therapy in PD is currently limited to a single preclinical animal study, supported by mechanistic in vitro findings and indirect evidence from other neurologic disease models; therefore, its relevance to PD remains to be established, and current evidence is insufficient to support conclusions regarding clinical efficacy. Together, these observations provide a rationale for further targeted preclinical investigation and support the systematic evaluation of Muse cells as a mechanistically distinct candidate for regenerative therapy in PD. Full article

The use of substances that modulate mitochondrial dynamics in cells of nervous tissue represents a new direction in targeted therapy for neurodegeneration. The aim of this study was to evaluate the effect of mitochondrial division inhibitor-1 (Mdivi-1) on neurons and microgliocytes of the substantia nigra under conditions of partial damage to the dopaminergic system. This study was conducted using the 6-hydroxydopamine model of parkinsonism in rats; a separate experimental group of animals received Mdivi-1 intraperitoneally at a dose of 20 mg/kg for 5 days. The intensity of immunofluorescence staining for Tomm20, MTCO1, pDrp1, and Mfn2 was evaluated in neurons of the substantia nigra, and microglial activation was morphologically assessed. It was found that unilateral administration of 6-OHDA led to pro-inflammatory changes in microglia and changes in mitochondrial markers of neurons on the side of the substantia nigra contralateral to the toxin injection. Mdivi-1 did not affect the damage and mitochondrial proteins of neurons in pars compacta of the substantia nigra; however, it changed mitochondrial markers in nervous cells of the pars reticulata. The use of Mdivi-1 to address abnormal processes in neurodegeneration requires additional studies that include a differential assessment of its effects on various cell types. Full article

Background: Impulse control disorders (ICDs) are a common non-motor complication in Parkinson’s disease (PD) patients with multiple negative consequences for the individual and caregivers. Although ICDs are strongly linked to dopaminergic therapy, particularly dopamine agonists, only a percentage of patients develop these behaviors, suggesting the involvement of additional susceptibility factors, including genetic variability. This review aims to analyze current knowledge on the genetic background of ICDs. Methods: A literature search was conducted in the PubMed and Scopus databases for peer-reviewed research regarding the role of genetics in ICDs, published in the English language from 1996 to 2026. References of the selected articles for possible additional articles were also screened in order to include most of the key recent evidence. Genes that are involved in the dopaminergic system play a central role in ICD susceptibility, although the findings in studies are often inconsistent and not replicated. Moreover, variants in genes related to the glutamatergic (e.g., GRIN2B), serotonergic (e.g., HTR2A and TPH2), and opioid systems (e.g., OPRK1 and OPRM1) have been implicated, supporting a multi-system contribution to ICD pathophysiology. Conclusions: Early recognition of genetic factors that increase susceptibility to ICDs in PD patients is awaited to increase diagnostic accuracy and expedite individualized treatment. Full article

Parkinson’s disease (PD) involves oxidative stress, proteotoxic aggregation, and neurotransmitter dysfunction, yet current therapies remain largely symptomatic. This study investigated whether Jujube polysaccharides (ZJP), a food-derived polysaccharide, confer neuroprotective and anti-aging benefits in Caenorhabditis elegans. ZJP was characterized for physicochemical features, antioxidant capacity, and in vivo safety. Effects were evaluated in wild-type N2 and PD models by measuring lifespan, locomotion, pharyngeal pumping, chemotaxis, α-syn::YFP fluorescence intensity, dopaminergic neuron integrity, adenosine triphosphate (ATP), reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), and lipofuscin. Stress resilience was assessed under heat (37 °C) and H₂O₂ exposure. RT-qPCR profiled genes related to stress responses and neurotransmission. ZJP showed no detectable toxicity at tested doses. ZJP extended mean lifespan in N2 (10.3–14.1%) and NL5901 (9.1%), improved locomotion, pharyngeal pumping, and chemotaxis, reduced lipofuscin (26.8–50.6%), and increased survival under heat (23.6%) and oxidative stress (38.1%). In PD models, ZJP reduced α-syn::YFP fluorescence by up to 54.9%, protected dopaminergic neurons, and increased ATP. It also lowered ROS and MDA levels while raising SOD and CAT activities. Gene expression changes were associated with enhanced oxidative stress resistance and with altered expression of genes involved in SKN-1/DAF-16-related stress-response signaling. These findings provide preliminary evidence that ZJP may promote longevity, stress resilience, and neuroprotection in C. elegans models of PD, supporting its potential as a candidate for further investigation in neuroprotection. Full article

The hypothesis that Group A beta-haemolytic Streptococcus (GAS) triggers an autoimmune cascade targeting basal ganglia dopaminergic circuits—producing obsessive–compulsive disorder (OCD), tic disorders, or chorea depending on the receptor subtype involved—is biologically compelling and supported by emerging molecular evidence. Yet PANDAS has remained a diagnostic conundrum since its original description in 1998, with ongoing uncertainty surrounding diagnostic criteria, the interpretation of streptococcal serology, and the distinction from primary neurodevelopmental disorders. This study aimed to review the diagnostic challenges of PANDAS, with focus on streptococcal serology interpretation, advances in dopamine receptor autoantibody biology, the genetic epidemiology of primary tic disorders, and the differential diagnosis of acute neuropsychiatric presentations in children. A structured narrative review was conducted using PubMed, MEDLINE, EMBASE, and the Cochrane Library for publications from 1998 to early 2025 addressing PANDAS, PANS, streptococcal antibodies, childhood movement disorders, autoimmune encephalitis, and the genetics of tic disorders. No currently available biomarker—including ASO, anti-DNase B, anti-basal-ganglia antibodies, or the Cunningham Panel—has demonstrated adequate individual-level diagnostic accuracy for PANDAS. Emerging molecular evidence identifies anti-D1R autoantibodies, acting via G protein-and beta-arrestin-mediated signalling, as candidate biomarkers for PANDAS/PANS neuropsychiatric phenotypes, and anti-D2R autoantibodies for Sydenham chorea movement phenotypes; independent replication in unselected populations is required. Primary tic disorders carry heritability estimates of 50–80% and first-degree familial risk ratios of approximately 18-fold in large population-based cohorts. Prospective blinded studies have not demonstrated a consistent population-level association between GAS infections and tic or OCD exacerbations: PANDAS and PANS remain diagnoses of exclusion. The high background prevalence of both GAS exposure and primary neurodevelopmental disorders in overlapping paediatric age ranges creates conditions for incidental temporal co-occurrence. In the absence of validated molecular biomarkers, diagnostic imprecision carries direct clinical consequences: children may be exposed to treatments with significant risk profiles—including IVIG, plasma exchange, and prolonged antibiotic prophylaxis—while evidence-based therapies are delayed. A stepwise diagnostic approach incorporating the full differential diagnosis is both an epistemological and a patient safety imperative. 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

Obesity resulting from melanocortin-4 receptor (MC4R) dysfunction is characterized by combined metabolic dysregulation and maladaptive reward-related behaviors that limit the durability of existing therapies. The endocannabinoid system is a central regulator of appetite, lipid metabolism, and reward processing; however, first-generation cannabinoid receptor 1 (CB1) antagonists were limited by adverse neuropsychiatric effects. SKNY-1 is an orally active tetrahydrocannabivarin (THCV) analog designed to engage pathway-biased CB1 signaling, modulate cannabinoid receptor 2 (CB2), and selectively inhibit monoamine oxidase B (MAO-B), with the objective of addressing both metabolic and behavioral components of obesity while minimizing central nervous system liability through biased CB1 signaling, CB2 modulation, and potential complementary MAO-B inhibition. Here, we integrated in vitro pharmacological profiling of SKNY-1 with in vivo evaluation in an adult mc4r(G894C) zebrafish model exhibiting obesity-associated metabolic and reward-related phenotypes. In vitro, SKNY-1 displayed low-potency modulation of CB1 cyclic AMP signaling (EC₅₀ ~30 µM) but more potent antagonism of the CB1 β-arrestin pathway (IC₅₀ ~6 µM), consistent with differential CB1 pathway modulation. SKNY-1 acted as a CB2 partial agonist (EC₅₀ ~0.1 µM), with antagonist activity emerging at higher concentrations, and selectively inhibited MAO-B at low affinity with no activity against MAO-A. In vivo, mc4r(G894C) zebrafish mutants exhibited dyslipidemia, hepatic triglyceride accumulation, altered appetite-regulatory gene expression, increased metabolic rate, and enhanced compulsive high-calorie feeding and nicotine-seeking behaviors. Oral administration of SKNY-1 for six days produced dose-dependent effects. Both doses normalized total cholesterol and low-density lipoprotein levels and reduced hepatic triglycerides toward wild-type values without affecting circulating triglycerides. The higher dose (200 ng per fish per day) induced significant body weight reduction while preserving body density and attenuated reward-associated feeding and nicotine-seeking behaviors. The lower dose (20 ng per fish per day) more effectively normalized the leptin a-to-ghrelin expression ratio. Collectively, these findings demonstrate that SKNY-1 engages integrated endocannabinoid and potential dopaminergic mechanisms to improve metabolic parameters and attenuate maladaptive reward-related behaviors in an MC4R-deficient vertebrate model, supporting its further translational investigation for obesity complicated by compulsive eating and substance-seeking behaviors. Full article

Restless legs syndrome (RLS) is a common yet underrecognized neurological disorder characterized by uncomfortable sensations and an irresistible urge to move he legs, typically following a circadian pattern. RLS frequently co-occurs with various other neurological diseases, raising questions about shared mechanisms and clinical consequences. This review synthesizes evidence on the prevalence, outcomes, and pathophysiology of RLS in various neurological disorders, including Parkinson’s disease, multiple sclerosis, migraine, dementia, stroke, epilepsy, and peripheral neuropathy. In Parkinson’s disease, RLS is linked to disease progression and dopaminergic therapy. In stroke and multiple sclerosis, RLS is associated with structural lesions at specific locations, such as the pons or spinal cord. In epilepsy, RLS is associated with refractory or nocturnal seizures. In neuropathies, disruption of small sensory fibers may contribute to RLS symptoms. In dementia, RLS adds diagnostic complexity. Overlapping mechanisms between RLS and its neurological comorbidities include altered sensorimotor processing, brainstem and spinal circuitry, and sleep/arousal regulation. RLS in neurological conditions often worsens sleep quality, mood, and fatigue, and contributes to reduced quality of life and worse outcomes. Future research should prioritize longitudinal designs, standardized diagnostic approaches, and mechanistically driven studies to clarify relationships between RLS and these neurological comorbidities. Full article

Hair follicles (HFs) are highly accessible mini-organs that house diverse somatic and stem cell populations with broad therapeutic potential. In this study, we investigate the untapped utility of plucked HFs as a non-invasive tissue source for regenerative medicine. We demonstrate the successful isolation and expansion of keratinocytes and mesenchymal stem cells (MSCs) from plucked follicles using an enzyme-free explant culture method. HF-derived keratinocytes retained their epithelial identity and were efficiently reprogrammed into induced pluripotent stem cells (iPSCs). These iPSCs were further directed toward definitive endoderm and pancreatic progenitor fates, confirming their robust autologous regenerative capacity. Flow cytometric analysis of HF-MSCs validated a characteristic mesenchymal profile, and these cells exhibited classical trilineage plasticity alongside the ability to differentiate into dopaminergic neural progenitors. Furthermore, proteomic and vesicular characterization of the autologous HF secretome (aHFS) revealed a rich enrichment of regenerative cytokines and exosomes. The aHFS demonstrated potent wound-healing bioactivity in vitro. Collectively, these findings establish the plucked hair follicle as a highly practical, scalable source for both cell-based and cell-free therapies, highlighting the clinical value of early-stage follicular biobanking for personalized medicine. Full article

Neurodegenerative disorders, including Parkinson’s disease (PD), are largely treated with symptomatic therapies, underscoring the need for strategies that target underlying disease mechanisms. Glucagon-like peptide-1 (GLP-1) and its receptor (GLP-1R), a class B G protein-coupled receptor best known for metabolic regulation, have attracted interest due to the increasing evidence of central nervous system (CNS) actions. This review synthesises mechanistic, preclinical, and clinical evidence examining GLP-1R signalling in PD and related neurodegenerative contexts. We integrate findings from cellular and animal models with early-phase clinical studies of GLP-1 receptor agonists (GLP-1RAs). Across experimental systems, GLP-1R activation engages conserved intracellular pathways—cAMP/PKA, PI3K/Akt, and ERK—that regulate mitochondrial function, oxidative stress, autophagy-lysosomal dynamics, and inflammatory signalling. In PD-relevant models, these pathways intersect with key pathogenic features, including α-synuclein accumulation, dopaminergic neuron vulnerability, and glial reactivity. Clinical studies to date demonstrate acceptable safety and tolerability, alongside biomarker evidence of central pathway engagement and variable effects on motor and non-motor outcomes. However, uncertainties remain regarding CNS target engagement, peripheral versus CNS mechanisms, and disease-stage dependence. Overall, the current evidence positions GLP-1R signalling as a biologically plausible therapeutic pathway in PD that warrants further mechanistic clarification and rigorous evaluation in ongoing and future clinical trials. Full article