Search Results (782)

Background. MiR-218 is a micro-RNA expressed in two isoforms (miR-218-1 and miR-218-2) in the brain and, within the mesencephalic area, it represents a specific regulator of differentiation and functional maturation of the dopamine-releasing neurons (DAn). Deletion of miR-218 isoforms within the midbrain alters the expression of synaptic mRNAs, the neuronal excitability of DAn of the substantia nigra pars compacta (SNpc), and their ability to release dopamine (DA) within the dorsal striatum. Objectives. Here we have investigated if miR-218 impacts the function of the DAn population adjacent to SNpc, the mesencephalic ventral tegmental area (VTA) innervating the nucleus accumbens (NAcc), and the medial prefrontal cortex. Methods. With the use of miR-218-1, miR-218-2, and double conditional knock-out mice (KO1, c-KO2, c-dKO), we performed electrophysiological recordings in VTA DAn to investigate firing activity, measurements of DA release in NAcc slices by constant potential amperometry (CPA), and in vivo behavioral analysis. Results. We find that KO1 VTA neurons display hyperexcitability in comparison with c-KO2, c-dKO, and wild type (WT) neurons. DA efflux in the NAcc core and shell is reduced in all single- and double-conditional KO striatal slices in comparison with controls. The KO1 mice display a tendency toward an anxiety-like trait, as revealed by the elevated plus maze test. Conclusions. Our data indicate that miR-218-1 is the isoform that mainly regulates VTA DA neuron excitability whereas both miR-218-1 and miR-218-2 impair DA release in the mesoaccumbens pathway. Full article

Aging of the central nervous system (CNS) involves widespread transcriptional and structural remodeling, prominently marked by synaptic loss, impaired neurogenesis, and glial dysfunction. While age-related gene expression changes have been documented for decades, recent genome-wide next-generation sequencing studies emphasize the importance of epigenetic mechanisms—such as DNA methylation and histone modification—in shaping these profiles. Notably, these modifications are potentially reversible, making them promising targets for therapeutic intervention. However, the mechanisms by which age-associated factors, such as inflammation and oxidative stress, orchestrate these epigenetic alterations across distinct CNS cell types remain poorly understood. In this review, we propose a framework for understanding how aging and neuroinflammation are regulated by epigenetic mechanisms, contributing to brain dysfunction and disease vulnerability. Full article

Traumatic brain injury (TBI) results in a cascade of neuropathological events, which can significantly disrupt synaptic integrity. This review explores the acute, subacute and chronic phases of synaptic dysfunction and loss in trauma which commence post-TBI, and their contribution to the subsequent neurological sequelae. Central to these disruptions is the loss of dendritic spines and impaired synaptic plasticity, which compromise neuronal connectivity and signal transmission. During the acute phase of TBI, mechanical injury triggers presynaptic glutamate secretion and Ca²⁺ ion-mediated excitotoxic injury, accompanied by cerebral edema, mitochondrial dysfunction and the loss of the mushroom-shaped architecture of the dendritic spines. The subacute phase is marked by continued glutamate excitotoxicity and GABAergic disruption, along with neuroinflammatory pathology and autophagy. In the chronic phase, long-term structural remodeling and reduced synaptic densities are evident. These chronic alterations underlie persistent cognitive and memory deficits, mood disturbances and the development of post-traumatic epilepsy. Understanding the phase-specific progression of TBI-related synaptic dysfunction is essential for targeted interventions. Novel therapeutic strategies primarily focus on how to effectively counter acute excitotoxicity and neuroinflammatory cascades. Future approaches may benefit from boosting synaptic repair and modulating neurotransmitter systems in a phase-specific manner, thereby mitigating the long-term impact of TBI on neuronal function. Full article

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder characterized by amyloid-β (Aβ) accumulation, synaptic dysfunction, and cognitive decline. Current pharmacological treatments provide only symptomatic relief without altering disease progression. Photobiomodulation therapy (PBMT), a light-based intervention, has shown neuroprotective potential, although its exact neurobiological mechanisms in AD pathogenesis remain obscure. In this study, we investigated the effects of PBMT using a 660 nm wavelength light-emitting diode (LED) in 5xFAD transgenic mouse, a well-established model of early-onset AD. Mice were subjected to once daily PBMT sessions over a defined treatment period and outcomes were assessed through immunohistochemical analysis of hippocampal regions (CA1, CA2, CA3, and dentate gyrus) alongside behavioral testing using the Y-maze spontaneous alternation task. PBMT significantly reduced Aβ plaque load across hippocampal regions, accompanied by improved preservation of neuronal morphology. Furthermore, PBMT significantly upregulated SIRT1 expression, a critical regulator of synaptic plasticity and memory processes. Behaviorally, PBMT-treated mice displayed enhanced spatial working memory compared with controls, indicating a functional benefit linked to the observed molecular and structural changes. These findings suggest that 660 nm PBMT attenuates hallmark AD pathology, promotes neuroprotective pathways, and improves cognition, highlighting its potential as a disease-modifying therapy that warrants further preclinical and clinical investigation. Full article

Astrocytes are the most common type of glial cell in the central nervous system (CNS). They have many different functions that go beyond just supporting other cells. Astrocytes were once thought of as passive parts of the CNS. However, now they are known to be active regulators of homeostasis and active participants in both neurodevelopmental and neurodegenerative processes. This article looks at the both sides of astrocytic function: how they safeguard synaptic integrity, ion and neurotransmitter balance, and blood-brain barrier (BBB) stability, as well as how astrocytes can become activated and participate in the immune response by releasing cytokines, upregulating interferons, and modulating the blood–brain barrier and inflammation disease condition. Astrocytes affect and influence neuronal function through the tripartite synapse, gliotransmission, and the glymphatic system. When someone is suffering from neurological disorders, reactive astrocytes become activated after being triggered by factors such as pro-inflammatory cytokines, chemokines, and inflammatory mediators, these reactive astrocytes, which have higher levels of glial fibrillary acidic protein (GFAP), can cause neuroinflammation, scar formation, and the loss of neurons. This review describes how astrocytes are involved in important CNS illnesses such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, amyotrophic lateral sclerosis, and ischemia. It also emphasizes how these cells can change from neuroprotective to neurotoxic states depending on the situation. Researchers look at important biochemical pathways, such as those involving toll-like receptors, GLP-1 receptors, and TREM2, to see if they can change how astrocytes respond. Astrocyte-derived substances, including BDNF, GDNF, and IL-10, are also essential for protecting and repairing neurons. Astrocytes interact with other CNS cells, especially microglia and endothelial cells, thereby altering the neuroimmune environment. Learning about the molecular processes that control astrocytic plasticity opens up new ways to treat glial dysfunction. This review focuses on the importance of astrocytes in the normal and abnormal functioning of the CNS, which has a significant impact on the development of neurotherapeutics that focus on glia. Full article

Microgravity exposure during spaceflight has been linked to cognitive impairments, including deficits in attention, executive function, and spatial memory. Both space missions and ground-based analogs—such as head-down bed rest, dry immersion, and hindlimb unloading—consistently demonstrate that altered gravity disrupts brain structure and neural plasticity. Neuroimaging data reveal significant changes in brain morphology, functional connectivity, and cerebrospinal fluid dynamics. At the cellular level, simulated microgravity impairs synaptic plasticity, alters dendritic spine architecture, and compromises neurotransmitter release. These changes are accompanied by dysregulation of neuroendocrine signaling, decreased expression of neurotrophic factors, and activation of oxidative stress and neuroinflammatory pathways. Molecular and omics-level analyses further point to mitochondrial dysfunction and disruptions in key signaling cascades governing synaptic integrity, energy metabolism, and neuronal survival. Despite these advances, discrepancies across studies—due to differences in models, durations, and endpoints—limit mechanistic clarity and translational relevance. Human data remain scarce, emphasizing the need for standardized, longitudinal, and multimodal investigations. This review provides an integrated synthesis of current evidence on the cognitive and neurobiological effects of microgravity, spanning behavioral, structural, cellular, and molecular domains. By identifying consistent patterns and unresolved questions, we highlight critical targets for future research and the development of effective neuroprotective strategies for long-duration space missions. Full article

Chronic stress induces mood disturbances, disrupts gut barrier function, and promotes low-grade systemic inflammation. This study assessed the therapeutic effects of atomoxetine (ATX), escitalopram (ESC), cannabidiol (CBD), and CBD-loaded lipid nanoparticles (CBD/LNP) in male rats exposed to repeated restraint stress. Stressed rats exhibited a 2.03-fold increase in interleukin-6 and a 1.89-fold increase in TNF-α, a 1.20-fold decrease in brain-derived neurotrophic factor, a 1.36-fold decrease in osteocalcin, accompanied by alterations in gut metabolites, particularly short-chain fatty acids (SCFAs; from 155.3 to 94.83 μmol/L), polyamines (from 273.6 to 192.4 μmol/L), and bile acids (BAs; from 21.19 to 14.53 μmol/L), compared with the control group. Protein analysis revealed gut barrier disruption and microglial/macrophage activation, accompanied by reduced synaptic plasticity. ATX improved gut permeability and reduced glial activation but did not restore osteocalcin. ESC provided neuroimmune benefits with limited and BA gut restoration and modulated the gut–brain axis and improved anxiety-like behaviors, partly by altering gut microbiota and metabolites. CBD and CBD/LNP treatment restored intestinal barrier function, as indicated by intestinal permeability in the range of 1.15–1.61-fold. These treatments also normalized bile acids (1.0–1.38-fold) and osteocalcin (1.0–1.28-fold) and significantly reduced glial activation (0.63–1.12-fold) as opposed to the non-treated stressed group. All treatments were found to be effective in correcting SCFA and polyamine levels. Histological analysis confirmed that CBD/LNP, ATX, and ESC ameliorated tissue alterations. These findings highlight CBD/LNP as a promising intervention for stress-induced gut–brain–bone axis disruption, supporting its potential as a therapeutic alternative through modulation of microbiota-driven gut–brain communication in stress-associated disorders. Full article

The global rise in high-fat diet (HFD) consumption and obesity has raised concerns about their long-term effects on brain health. This review addresses how HFDs, including ketogenic diets (KDs), influence the central nervous system (CNS) and may contribute to neurodegenerative processes. The findings show that prolonged HFD exposure is associated with altered brain metabolism, increased oxidative stress, neuroinflammation, and impaired synaptic plasticity, particularly in regions like the hippocampus and hypothalamus. These changes may affect cognitive function and accelerate neurodegenerative mechanisms linked to disorders such as Alzheimer’s and Parkinson’s disease. While certain types of KD appear to exert neuroprotective effects—such as improved motor outcomes in experimental Parkinson’s disease models—evidence remains inconsistent, and concerns about their long-term safety persist. This review emphasizes that the impact of high-fat nutrition on the CNS depends on fat type, exposure duration, and individual factors such as age and sex. Overall, further research is needed to distinguish between harmful and potentially therapeutic dietary fat patterns and to better understand their influence on brain health across the lifespan. Full article

Aging is accompanied by complex cellular and molecular changes that compromise CNS function. Among these, glial cells (astrocytes, microglia, and oligodendrocytes) play a central role in maintaining neural homeostasis, modulating synaptic activity, and supporting metabolic demands. Emerging evidence indicates that aging disrupts glial cell physiology through processes including mitochondrial dysfunction, impaired proteostasis, chronic low-grade inflammation, and altered intercellular signaling. These alterations contribute to synaptic decline, myelin degeneration, and persistent, low-grade inflammation of the CNS. This review synthesizes current knowledge on the bidirectional relationship between aging and glial cell dysfunction, highlighting how age-related systemic and CNS-specific factors exacerbate glial impairments and, in turn, accelerate neural deterioration. Finally, this study discusses some potential therapeutic strategies aimed at preserving or restoring glial function to promote CNS resilience in aging populations. Understanding this interplay offers critical opportunities for mitigating cognitive decline and improving quality of life in older adults. Full article

Background/Objectives: Glutamatergic neurotransmission is essential for the normal functioning of the retina. Photoreceptor to bipolar and bipolar to ganglion cell signaling is mediated by L-glutamate, which is stored in and released from vesicular glutamate transporter 1 (VGLUT1) containing synaptic vesicles. VGLUT1 is expressed postnatally, P2 onwards, and is required for the glutamatergic retinal wave observed between P10 and P12 in the developing mouse retina. P9–P13 postnatal age is critical for retinal development as VGLUT1 expressing ribbon synapses activate in the outer and inner plexiform layers, and rod/cone mediated visual signaling commences in that period. Although it has been hypothesized that glutamatergic extrinsic signaling drives cell cycle exit and initiates cellular differentiation in the developing retina, it is not clear whether intracellular, synaptic, or extrasynaptic vesicular glutamate release contributes to this process. Recent studies have attempted to decipher VGLUT’s role in retinal development. Here, we investigate the potential effect of genetic loss of VGLUT1 on early postnatal histogenesis and development of retinal neural circuitry. Methods: We employed immunohistochemistry and electrophysiology to ascertain the density of glutamatergic, cholinergic, and dopaminergic cells, spontaneous retinal activity, and light responses in VGLUT1 null retina, and contrasted them with wildtype (WT) and melanopsin null retina. Results: We have demonstrated here that VGLUT1 null retina shows signs of age dependent retinal degeneration, similar to other transgenic mice models with dysfunctional photoreceptor to bipolar cell synapses. The loss of VGLUT1 specifically alters glutamatergic cell density and morphological maturation of retinal ganglion cells. Moreover, VGLUT2 expression is lost in the majority of VGLUT2 cones in the absence of VGLUT1 coexpression, except when VGLUT2 coexpresses transiently with VGLUT3 in these cones, or when VGLUT1 null mice are dark reared. Conclusions: We present the first evidence that synaptic or extrasynaptic postnatal glutamate release from VGLUT1 containing vesicles impacts histogenesis of glutamatergic cells, pruning of retinal ganglion cell dendrites and VGLUT2 expression in cones. Full article

Background and Objective: Humanized models of Alzheimer’s disease (AD) provide valuable tools for investigating the mechanisms of this neurodegenerative disorder, the leading cause of dementia. These models enable the study of AD progression and the potential disease-modifying properties of drugs or dietary nutrients delivered through nutrition. Here, we examine molecular markers of metabolic and synaptic dysfunction in the hippocampus of 6-month-old 3×Tg-AD mice and assess whether a dietary insulin sensitizer can delay synaptic decline. Methods: First we characterized the molecular phenotype of 3×Tg-AD at 12 months using shotgun proteomics and phosphoproteomics to assess metabolic and synaptic changes in the hippocampus. Then, we characterized the effects of early daily oral D-chiro-inositol (DCI, Gyneos^®) for three months, starting at 3 months of age, to test restoration of insulin signaling and glutamatergic synaptic markers. To this end we evaluated a) insulin signaling pathway components (insulin receptor, IRS1, PI3K, AKT, GSK3β) at mRNA, protein, and phosphorylation levels, and b) the expression of glutamate receptors (mGluR5, GluR1, GluR2, NMDAR1, NMDAR2A, NMDAR2B). Sex effects were explored. Results: 12-month 3×Tg-AD mice exhibit metabolic and synaptic dysfunction in the hippocampus, with phosphoproteomic changes suggesting altered glutamatergic synapses. At 6 months, disruptions in insulin signaling were evident, including altered expression and phosphorylation of insulin pathway components, and changes in glutamate receptor subunits. Early DCI treatment largely reversed these alterations. Several effects showed sex dependency. Conclusions: Early insulin-sensitizing intervention via DCI can restore insulin signaling and counteract hippocampal synaptic impairments in this AD model, supporting the potential for nutrient-based strategies to delay synaptic decline. Sex differences underscore the need to tailor therapeutic approaches in modifying AD progression. Full article

Neurogranin (NRGN), a synaptic protein essential for plasticity and memory function, is gaining recognition as a promising biomarker for mild traumatic brain injury (mTBI). This systematic review brings together findings from six studies that measured neurogranin levels in biofluids—including serum, cerebrospinal fluid (CSF), plasma, and exosomes—during both the acute and chronic phases following injury. In the acute phase of mTBI, elevated levels of neurogranin were consistently observed in serum samples, suggesting its potential as a diagnostic marker. These increases appear to reflect immediate synaptic disturbances caused by injury. In contrast, studies focusing on the chronic phase reported a decrease in exosomal neurogranin levels, pointing to ongoing synaptic dysfunction well after the initial trauma. This temporal shift in neurogranin expression highlights its dual utility—both as an early indicator of injury and as a longer-term marker of synaptic integrity. However, interpreting these findings is not straightforward. The studies varied considerably in terms of sample type, timing of measurements, and control for potential confounding factors such as physical activity. Such variability makes direct comparisons difficult and may influence the outcomes observed. Additionally, none of the studies included proteoform-specific analyses of neurogranin, an omission that limits our understanding of the molecular changes underlying mTBI-related synaptic alterations. Due to heterogeneity across study designs and outcome measures, a meta-analysis could not be performed. Instead, a narrative synthesis was conducted, revealing consistent patterns in neurogranin dynamics over time and underscoring the influence of biofluid selection on measured outcomes. Overall, the current evidence supports neurogranin’s potential as both a diagnostic and mechanistic biomarker for mTBI. Yet, to fully realize its clinical utility, future research must prioritize standardized protocols, the inclusion of proteoform profiling, and rigorous longitudinal validation studies. Full article

Metal oxides are the most widely used material for the resistive switching layer of memristors. Nevertheless, the majority of oxide-based memristors exhibit binary switching, restricting the emulation of neuronal synaptic behaviors. In this paper, the shift from digital-to-analog switching behavior is achieved by inserting an Al₂O₃ layer atop Zr-doped HfO₂. The TiN/Al₂O₃/HZO/W/Si device exhibits long resistance state retention time and consistency. In addition, by applying a varying voltage, the device exhibits up to 20 continuous resistance states, which is highly significant for high-density storage. Upon the application of a programmable pulse signal, the device’s conductance undergoes continual alteration, reflecting long-term potentiation (LTP) and long-term depression (LTD) synaptic characteristics. The conduction mechanism of the device is studied through physical model fitting and schematic diagrams. Full article

Liquid–liquid phase separation (LLPS) in cell biology has revolutionized our understanding of how cells organize biochemical reactions and structures through dynamic, membraneless organelles (MLOs). In neurons, LLPS-driven processes are particularly important for regulating synaptic plasticity, RNA metabolism, and responses to environmental stressors. Over the past decade, LLPS has gained increasing attention in neurobiology as a framework to interpret altered synaptic functions in various neurodevelopmental disorders (NDDs). These diseases comprise a diverse spectrum of clinical and pathological symptoms (e.g., global developmental delay, impaired cognitive and mental functions, as well as social withdrawal). Recent studies have highlighted how mutations in proteins containing intrinsically disordered regions (IDRs)—key drivers of LLPS—can alter condensate properties, resulting in persistent or defective MLO formation. These aberrant assemblies may disrupt RNA transport, splicing, and translation in developing neurons, thereby contributing to disorder pathology. IDRs are known to be enriched in membraneless components, such as stress granules, nuclear paraspeckles, and P-bodies, where they play crucial role in the formation, maintenance, and function of protein–RNA networks. This review explores the role of stress-induced MLOs in the nervous system, the molecular principles governing their formation, and how their dysfunction bridges the gap between environmental stress responses and neurodevelopmental impairment. Full article

Opioid-use disorder (OUD) poses a growing global health crisis, with chronic opioid exposure linked not only to addiction but also to enduring neurological impairments. While traditional research has focused primarily on neuronal alterations, emerging evidence underscores the pivotal role of astrocytes, abundant glial cells in the central nervous system, and their secreted extracellular vesicles (EVs) in opioid-mediated neuropathology. This review delineates the mechanistic roles of astrocytes and astrocyte-derived EVs (ADEVs) across a spectrum of opioids, including morphine, heroin, fentanyl, codeine, tramadol, buprenorphine, and methadone. Opioids disrupt astrocytic homeostasis by impairing glutamate regulation, altering the redox balance, and activating pro-inflammatory signaling pathways. In response, astrocytes release EVs enriched with neurotoxic cargo, including amyloidogenic proteins, cytokines, microRNAs, and long non-coding RNAs, that propagate neuroinflammation, compromise blood–brain barrier (BBB) integrity, and exacerbate synaptic dysfunction. Preclinical models and in vitro studies reveal drug-specific astrocytic responses and ADEV profiles, implicating these vesicles in modulating microglial function, neuroimmune signaling, and neuronal viability. Notably, morphine-induced ADEVs promote amyloidosis and inflammatory signaling, while heroin and fentanyl affect glutamatergic and inflammasome pathways. Even opioids used in therapy, such as buprenorphine and methadone, alter astrocyte morphology and EV cargo, particularly during neurodevelopment. Collectively, these findings advance a neuro-glial paradigm for understanding opioid-induced brain injury and highlight ADEVs as both biomarkers and mediators of neuropathology. Targeting astrocyte-EV signaling pathways represents a promising therapeutic avenue to mitigate long-term neurological consequences of opioid exposure and improve outcomes in OUD. Full article