Search Results (921)

Diabetic retinopathy (DR) is more than a capillary disorder. Diabetes affects neurons, glial cells, vascular cells, and immune signals within the retinal neurovascular unit (NVU). Retinal neurovascular coupling (NVC) is a useful functional marker of NVU integrity because it reflects the rise in local blood flow that follows neural activity. Many human flicker-light studies report smaller vessel dilation or weaker flow responses in diabetes. This finding can appear even in patients without clear fundus lesions. When NVC is reduced, retinal tissue may receive less oxygen. Lower oxygen delivery can raise oxidative stress and promote inflammation. These changes can then worsen vascular injury. This review describes key NVC pathways and diabetes-related NVU changes in Müller glia, astrocytes, microglia, pericytes, and endothelial cells. The review highlights sympathetic activation as a common stress signal. Pain, anxiety, perioperative stress, and sleep loss can increase sympathetic activity and circulating catecholamines. In the diabetic retina, vascular reserve is often limited. Under these conditions, catecholamines can increase mural cell constriction, reduce nitric oxide (NO)-dependent relaxation, and increase endothelial activation and barrier strain. These effects can shift the baseline state of glial and immune cells and further weaken NVC. The review also summarizes translational tools that can test these links. These tools include heart rate variability, standardized NVC protocols with diameter and flow measures, and retinal organoid and organ-on-a-chip platforms with controlled adrenergic exposure. The review discusses perioperative care packages that reduce stress responses, protect sleep, and manage glucose as practical ways to support retinal microcirculation. More longitudinal human studies are still needed. Retina-specific perioperative endpoints are also needed to clarify causality and to guide intervention trials. 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

Canine cognitive dysfunction (CCD) is a common age-related neurodegenerative disorder in dogs that shares several pathological and clinical features with human Alzheimer’s disease (AD). In both species, β-amyloid (Aβ) accumulates within the brain parenchyma and cerebral vessel walls and is associated with synaptic loss, oxidative stress, mitochondrial dysfunction, and chronic neuroinflammation, ultimately leading to progressive cognitive decline. Increasing evidence indicates that impairment of brain clearance mechanisms, particularly the glymphatic system, represents a central pathogenic mechanism in both CCD and AD. The glymphatic system is a glia-dependent perivascular network involved in the clearance of Aβ and other metabolic waste products from the brain. Its function declines with aging, vascular disease, and astrocytic alterations, including changes in aquaporin-4 distribution. Reduced glymphatic and periarterial drainage promotes the retention and aggregation of Aβ and tau proteins. Compared with AD, tau pathology in CCD is generally less extensive, supporting the interpretation of CCD as an Aβ-predominant condition and a partial pathological analog of Alzheimer’s disease. Clinically, CCD is characterized by a constellation of behavioral changes including, disorientation, altered social interactions, sleep–wake cycle disturbances, a loss of housetraining, changes in activity levels, and increased anxiety, commonly summarized by the DISHAA acronym. Overall, CCD represents a valuable spontaneous large-animal model for investigating neurodegenerative mechanisms and clearance-related therapeutic targets relevant to both veterinary and human medicine. Full article

In amyotrophic lateral sclerosis (ALS), a central event is the withdrawal of the motor nerve terminal from its target muscle. Whether this defect is driven by faults in the motor neuron or faults that originate within the muscle remains an area of investigation. In this review, we focus on the pathological abnormalities that are found in skeletal muscle, focusing, when possible, on human ALS, with support from ALS animal models. We begin with an overview of skeletal muscle, including a review of muscle fiber type, motor units and the neuromuscular synapse. Next, we provide a description of the clinical and biomarker changes that occur in the muscles of patients with ALS. We provide an extensive account of the histopathological changes that are evident in ALS muscle, such as fiber type grouping, muscle inflammation, protein misfolding, mitochondrial dysfunction, and alterations in neuromuscular junctions and muscle satellite cells. Our review then concludes with an update of metabolic and molecular–genetic changes that are found in ALS muscle. The evidence shows that muscle can be an additional target for therapy in ALS, in combination with therapies targeting neurons and glia within the central nervous system (CNS). Full article

The ontological categorization of the cellular elements of the brain was proposed over a century ago by Santiago Ramón y Cajal (neurons, astroglia) and Pío del Río-Hortega (oligodendroglia, microglia). It combines histochemical observations of morphology with allied inferences about the specialized functions and origins (ectoderm or mesoderm) of each cellular element. This ontology shapes modern neuroscience, with the main non-neuronal cells—astroglia, oligodendroglia and microglia—viewed as having distinct primary roles relating respectively to the metabolic support, myelination and immunoprotection of neurons, the information signaling cells. Yet contemporary techniques, ranging from electrophysiology to single-cell transcriptomics and ultrahigh resolution spectroscopy, are revealing intersecting molecular profiles and functional capacities of these cell groups, for example metabolic support, neuroimmune and signaling functions in oligodendroglia. Here we identify discrepancies in current glial paradigms, from empirical, evolutionary and pragmatic perspectives. We suggest a subset of small, iron-rich glial cells, usually with few processes, often viewed as oligodendroglia with myelin-related primary functions, instead have iron-related primary functions that are central to all aspects of brain activity. We call these ‘ferriglia’. We discuss implications for pathogenesis across the spectrum of neuropsychiatric and neurological disorders, including neurodegenerative conditions such as Alzheimer’s disease and other less common cognitive, movement and neurobehavioral disorders, stroke and cerebrovascular disease, glioblastoma and other brain cancers and neuroimmune conditions. We also briefly address the question of where ferriglia may reside within existing glial compartments and lineages, implications for the ontological classification of other glial cells, and research challenges that must be overcome going forward. Full article

Background/Objectives: Evidence indicates that aberrant glutamate transporter function and expression are linked to the pathophysiology of comorbid major depressive disorder (MDD) and pain. We have previously reported that cefepime (CFP) attenuates lipopolysaccharide (LPS)-evoked pain and depression by regulating hyperglutamatergic activity in male mice. However, the effects of CFP on LPS-evoked pain, depression-related anxiety, and cognitive impairment in female mice regarding sex-specific glial mechanisms remain unknown. Methods: Using behavioral paradigms, we evaluated the therapeutic potential of CFP in mitigating LPS-evoked pain, depression-related anxiety, and cognitive impairment in female mice. Furthermore, we used Western blot analysis to examine the effects of CFP on ionized calcium-binding adaptor molecule 1 (Iba-1) and glutamate transporter 1 (GLT-1) protein levels in the prefrontal cortex (PFC) and hippocampus (HPC). We also measured tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) concentrations in the HPC and PFC after CFP treatment using ELISA. Results: Pretreatment with CFP significantly increased the mechanical threshold and withdrawal latency in female mice. Additionally, systemic treatment with CFP markedly reduced immobility during the forced swim and tail suspension tests. Moreover, pretreatment with CFP remarkably augmented the open arm time during elevated plus maze test and spontaneous alternation between arms during Y-maze test. Western blot analysis indicated that systemic administration of CFP significantly reversed the downregulation of astroglial GLT-1 expression and reduced the microglial Iba-1 protein levels in the HPC and PFC. Furthermore, pretreatment with CFP significantly attenuated the LPS-evoked increase in the production of pro-inflammatory cytokines in the HPC and PFC. Conclusions: These results represent the novel inaugural report of a combined pain-MDD phenotype in female mice. The findings imply that positive glutamate transporter modulator CFP could be a novel treatment for comorbid pain and MDD in female patient population. Full article

The zebrafish (Danio rerio) is a widely used model for studying retinal regeneration. In adults, light-induced retinal damage (LIRD) serves as an environmental phototoxic stressor that induces photoreceptor degeneration and regenerative responses, whereas larval models remain comparatively underexplored. In this study, we validate a larval LIRD paradigm as a versatile system for studying acute phototoxic injury and early regeneration-associated transcriptomic responses. Using high-throughput RNA sequencing, we profiled retinal transcriptional changes 48 h post-LIRD and complemented these findings with targeted pharmacological modulation of redox signaling. Larval LIRD induced robust activation of canonical apoptotic and regeneration-associated pathways, recapitulating key features of adult LIRD models while engaging previously underexplored gene-regulatory networks. Among these, pathways related to oxidative stress responses, antioxidant enzymes, and oxygen metabolism were prominently regulated. Functional attenuation of oxidative stress using the N-acetylcysteine reduced phototoxic injury-induced apoptosis and proliferation, while inflammatory markers remained largely unaffected. Conversely, subtoxic intra-retinal hydrogen peroxide exposure was sufficient to induce proliferative markers without eliciting apoptosis response. At the signaling level, modulation of oxidative stress influenced components of growth-associated signaling pathways activated during early injury response. Together, these findings support a role for oxidative stress as a key component of early injury-associated signaling in larval retinal regeneration. This study integrates histological, transcriptomic, and pharmacological analyses to interrogate early regenerative programs and provides a comprehensive transcriptomic resource for exploring redox-associated mechanisms in retinal injury and repair. Full article

Neuroinflammation mediated by reactive microglia, the immune cells of the brain, contributes to numerous neuropathologies. Damage-associated molecular patterns (DAMPs), released from stressed or damaged cells, are implicated in neuroinflammation. Succinate, a tricarboxylic acid cycle intermediate, can accumulate intracellularly and be released into the extracellular space where it may function as a DAMP-like molecule. However, its specific roles in central nervous system (CNS) neuroimmune responses, particularly when acting extracellularly, remain largely unexplored. This study utilizes cell membrane-impermeable disodium succinate to model extracellular action and cell-permeable diethyl succinate to assess the intracellular activity of this metabolite in cell culture models. We demonstrate that extracellular disodium succinate significantly reduces the secretion of pro-inflammatory cytokines tumor necrosis factor-α (TNF) and interleukin (IL)-6, and lowers neurotoxic and phagocytic activities of immune-stimulated BV-2 murine microglia. It also rescues lipopolysaccharide (LPS)-induced decreases in mitochondrial respiration in human peripheral blood mononuclear cells (PBMCs) used as microglia models, which correlates with its actions on phagocytosis. In contrast, while intracellular diethyl succinate reduces TNF and IL-6 secretion, it does not reduce BV-2 microglia toxicity towards murine NSC-34 neuronal cells, indicating location-dependent effects. These results support extracellular succinate as a novel CNS DAMP with a predominantly anti-inflammatory action on microglia. Full article

Background: The principal glial cells of the retina, Müller glia, play a central role in retinal regeneration in teleost fish and have recently attracted attention as potential sources of neuronal regeneration in mammals. Objectives: In this study, we examined whether SV40-immortalized rat Müller glia could be directed toward neuronal differentiation using a non-genetic approach with defined culture conditions. Methods: Comprehensive transcriptomic profiling by RNA sequencing indicated that changes in culture medium alone could induce transcriptional reprogramming toward a neuronal lineage. Results: Specifically, expression of Müller glia-related genes decreased, while a subset of photoreceptor-related transcription factors and specific genes showed altered expression, suggesting early-stage induction toward a photoreceptor-like fate. This finding suggests that even immortalized cells may exhibit activation of neuronal genes through non-genetic culture interventions. Gene set enrichment analysis further revealed upregulation of pathways related to the synaptic vesicle cycle, metabolic activation, oxidative stress defense, and lysosomal function, consistent with initiation of neuronal differentiation. Conversely, pathways associated with cell cycle regulation and stemness signaling were downregulated, reflecting a transition from a proliferative to a differentiation-prone state. Collectively, these results provide preliminary molecular markers for early neuronal induction and potential targets for chemical screening. Conclusions: Importantly, this strategy enables neuronal-like differentiation of Müller glia without genetic manipulation, offering a safe and cost-effective platform. Overall, our findings may support the development of in vitro models for retinal neuroregeneration and facilitate research toward regenerative therapies for retinal disorders. Full article

Alpha-synuclein (αSyn) is one of the most abundant proteins in the nervous system and is currently associated with devastating synucleinopathies, yet its biology extends far beyond this. In this review, we suggest that αSyn-driven disease emerges within specific neural circuits through the combined effects of cell-type-specific roles, subcellular environments, post-translational modifications (PTMs), and co-pathology. These interacting and additive dimensions, rather than αSyn alone, generate the pathological diversity, shaping whether pathology manifests as Parkinson’s disease (PD), Parkinson’s disease dementia (PDD), dementia with Lewy bodies (DLB), multiple system atrophy (MSA), or mixed dementia phenotypes. We integrate recent advances on the physiological roles of αSyn in neurons and glia (astrocytes, oligodendrocytes, and microglia), its compartment-dependent (e.g., synaptic and nuclear) functions, and the molecular transitions (e.g., mediated by pS129) that convert functional assemblies into pathogenic conformers. Building on this foundation, we outline mechanisms through which these factors contribute to disease-specific vulnerability, progression, and clinical heterogeneity. Finally, we highlight how this multidimensional perspective on αSyn biology can inform the development of next-generation biomarkers that support precision therapies across distinct disorders. Full article

Chronic neuroinflammation is increasingly implicated in the progression of neurodegenerative diseases, yet the mechanisms linking metabolic stress, innate immune activation, and neuronal vulnerability remain incompletely defined. Retinitis pigmentosa (RP), despite its genetic heterogeneity, exhibits convergent inflammatory and metabolic alterations during disease progression, providing a useful model for studying immune-mediated neurodegeneration. This review summarizes current evidence from experimental models of retinal degeneration and human retinal studies to examine how sustained neuroinflammation is established in RP. We focus on the coordinated roles of retinal microglia and Müller glia in sensing photoreceptor stress and shaping the inflammatory microenvironment. Microglia are activated early in disease and contribute to progression through inflammatory signaling, phagoptosis, metabolic adaptation, and inflammasome-associated pathways. Müller glia, in turn, modulate metabolic homeostasis and propagate inflammatory signals across retinal layers. We also discuss how stress-responsive regulatory pathways, including p53-associated signaling, influence redox balance, iron handling, and inflammatory persistence without acting as primary apoptotic drivers. Together, these findings support a model in which chronic immunometabolic dysregulation contributes to retinal degeneration and highlight inflammation-related processes as potential targets for mutation-independent therapeutic strategies. Full article

Background: Posttraumatic stress disorder (PTSD) is a mental illness in which central stress-regulating regions, including locus coeruleus (LC) and paraventricular nucleus of hypothalamus (PVN), play key roles. Clonidine, a central sympatholytic drug, can inhibit LC activity and reduce PTSD-related symptoms, suggesting noradrenergic involvement. Glia-driven immune mechanisms may link LC activity to PVN responses. Since TRPA1 ion channel is implicated in both neuroinflammation and stress adaptation, we aimed to determine whether its presence modulates the function of brain structures contributing to PTSD-related alteration in central stress adaptation. Methods: Foot shock PTSD model was applied to Trpa1 wild-type (WT) and knockout (KO) mice, and outcomes were assessed four weeks later. Immunohistochemistry was used to evaluate tyrosine hydroxylase (TH) levels in the LC and glial activation in the PVN. Behavioral effects of clonidine and circulating corticosterone levels were also examined. Results: Stress increased LC/TH immunoreactivity and PVN glial activation. Trpa1 deletion exaggerated LC/TH responses but reduced PVN astrocyte activation. Clonidine increased freezing and decreased jumping (a hyperarousal marker). KO mice showed enhanced jumping and did not respond to clonidine. Corticosterone levels remained unchanged. Conclusions: TRPA1 may support stress adaptation in PTSD by regulating LC noradrenergic output and PVN neuroinflammation, independently of α₂-adrenergic signaling. Full article

T-cell intracellular antigen 1 (TIA1) is a multifunctional RNA-binding protein (RBP) belonging to the RNA recognition motif (RRM) family. Under steady-state conditions, it is predominantly localized in the nucleus and highly expressed in the nervous system, where it regulates neuronal and glial functions. TIA1 modulates mRNA splicing, stability, and translation and promotes stress granule (SG) assembly under cellular stress. Recent studies indicate that the spatiotemporal dynamics of TIA1 in neurodegenerative contexts influence disease progression by regulating inflammatory responses, apoptosis, and related pathways. This review discusses the molecular structure and functions of TIA1, focusing on its expression in neurons and glia, as well as its implications in neurodegenerative disorders and stroke. The findings highlight TIA1 as a promising target for novel neuroprotective therapeutic strategies. Full article

Satellite glial cells (SGCs) in sensory ganglia are increasingly recognized as active regulators of neuronal excitability and inflammatory signaling involved in pain conditions. In craniofacial and orofacial pain, trigeminal SGCs exhibit stimulus-dependent responses that develop over time and contribute to disease-related plasticity. Additionally, advances in experimental modeling, computational analysis, and data integration have fueled interest in “digital twins” as tools for hypothesis generation and decision support in biomedicine. However, most current biomedical applications are loosely defined and rarely explicitly address glial biology. Here, we propose a digital twin-inspired framework focused on trigeminal satellite glial cells to combine stimulus-response experiments with computational state modeling. Instead of claiming a fully developed digital twin, we describe a hybrid experimental–computational approach where glial activation states are inferred from measurable outputs, iteratively refined, and used to explore what-if scenarios related to pain mechanisms and treatments. These scenarios are intended to guide experimental design and hypothesis prioritization rather than to generate clinical predictions. We detail how this framework could enhance understanding of underlying mechanisms, prioritize potential interventions, and align with New Approach Methodologies (NAMs) and the 3Rs by reducing exploratory animal use. We also discuss key limitations, including biological simplification, uncertainty, and translational challenges. By viewing glial systems as dynamic, updateable entities rather than static readouts, this approach offers a practical and ethically grounded pathway toward more integrated research on craniofacial pain. Full article

Phantom limb pain (PLP) is a frequent and often persistent consequence of limb amputation, characterized by pain perceived in the absent limb. Despite decades of research, its biological basis remains incompletely understood, and available treatments often provide inconsistent relief. This reflects the complex and heterogeneous nature of phantom limb pain, which cannot be explained by a single anatomical site or pathological process. Current evidence suggests that phantom limb pain emerges from the interaction of changes occurring at multiple levels of the nervous system. Peripheral nerve injury associated with amputation induces molecular and cellular alterations that may influence early nociceptive signaling. These changes can interact with adaptive and maladaptive responses within the spinal cord, including altered synaptic transmission and neuron–glia interactions, which may facilitate sustained amplification of pain-related signals. At supraspinal levels, long-term adaptations within distributed neural networks involved in sensory, motor, and affective processing may contribute to the persistence of pain perceptions in the absence of ongoing peripheral input. Immune-related signaling and long-term regulation of gene expression further modulate these processes and may contribute to inter-individual variability. In this narrative review, we synthesize current experimental and clinical evidence addressing the molecular and cellular processes associated with phantom limb pain following lower limb amputation. Findings are integrated across peripheral, spinal, and supraspinal levels, with consideration of immune-related and regulatory influences. By highlighting areas of convergence, uncertainty, and existing knowledge gaps, this review aims to provide a coherent biological framework that may support future experimental and translational research in this challenging field. Full article