Search Results (121)

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

γ-aminobutyric acid (GABA), the primary inhibitory neurotransmitter in the central nervous system (CNS), regulates neuronal excitability, synaptic plasticity, and oscillatory activity essential for cognition, emotion, and behavior. Disruptions in GABAergic signaling are increasingly recognized as key contributors to a range of neurodevelopmental disorders (NDDs), including schizophrenia (SZ), autism spectrum disorder (ASD), major depressive disorder (MDD), bipolar disorder (BD), and intellectual disability (ID). In this review, we analyze the data available from the literature concerning the components of the GABA pathway. We describe the main steps of GABA metabolism, including GABA synthesis and release, GABA receptors neurotransmission, GABA reuptake and catabolism, and evaluate their involvement in the pathogenesis of neurodevelopmental disorders. We suggest the possibility of existence of so far undescribed mechanisms which maintain the concentrations of GABA at a relatively physiological level when the function of glutamic acid decarboxylases is compromised by mutations. Searching for these mechanisms could be important for better understanding neurodevelopment and could give a clue for future searches for new therapeutic approaches for treating or alleviating the symptoms of BD and SZ. We also argue that the metabolic stage of the GABA pathway has only a minor direct effect on GABA signaling and rather causes clinical effects due to accumulation of neurotoxic byproducts. Full article

Fear memory is a critical adaptive process that enables organisms to avoid potential threats and survive in complex environments. Traditionally viewed as a neuronal phenomenon, emerging evidence has demonstrated that astrocytes play a fundamental role in fear memory acquisition, consolidation, extinction, and retrieval across the distributed neural network encompassing the amygdala, hippocampus, and prefrontal cortex. This review presents recent advances in our understanding of the molecular mechanisms by which astrocytes modulate fear memory processing within the tripartite circuit. We examine how astrocytes contribute to synaptic plasticity, neurotransmitter regulation, metabolic support, and intercellular communication during the different phases of fear memory processing. Particular emphasis is placed on the region-specific functions of astrocytes, their dynamic interactions with neurons, and their therapeutic implications for treating fear-related disorders such as post-traumatic stress disorder (PTSD) and anxiety disorders. The integration of cutting-edge technologies, including spatial transcriptomics, optogenetics, and chemogenetics, has revealed sophisticated astrocyte–neuron communication mechanisms that challenge the traditional neuron-centric view of memory processing. Full article

The growing prevalence of mental health issues and cognitive impairment poses a significant challenge to global public health. Conditions such as depression, anxiety, neurodegenerative diseases, and stress-related cognitive dysfunction are becoming more common, while conventional pharmacotherapies are often limited by suboptimal efficacy, adverse side effects, and concerns about long-term use. Against this backdrop, neurophytochemistry—the study of plant-derived bioactive compounds—has emerged as a promising area of research. This review explores the potential of selected phytochemicals to support mental well-being and cognitive function via various molecular mechanisms. Compounds such as apigenin, hesperidin, and epigallocatechin gallate have been shown to have a significant impact on key regulatory pathways. These include enhancing neurogenesis via brain-derived neurotrophic factor, modulating neurotransmitter systems (such as GABA and serotonin), and attenuating oxidative stress and neuroinflammation. The therapeutic relevance of these compounds is discussed in the context of depression, anxiety, Alzheimer’s disease, Parkinson’s disease, and stress-related cognitive dysfunction, often referred to as ‘brain fog’. This review synthesizes evidence published between 2010 and 2025 from several scientific databases, including PubMed, Scopus, Web of Science, and Embase. Preliminary evidence from in vitro studies and animal models indicates that neurophytochemicals could enhance synaptic plasticity, protect neurons from oxidative damage, and modulate inflammatory pathways, particularly those involving NF-κB and the Nrf2/ARE antioxidant response. In addition, early human clinical trials have shown that phytochemical supplementation can lead to improvements in mood regulation, stress response, and cognitive performance. Furthermore, emerging evidence suggests that the gut–brain axis plays a key role in mediating the effects of phytochemicals. Several compounds have been found to modulate the composition of gut microbiota in ways that could enhance the function of the central nervous system. While the initial results are encouraging, more high-quality clinical trials and mechanistic studies are required to validate these findings, optimize dosage regimens, and guarantee the safety and efficacy of long-term use. Thus, neurophytochemicals represent a promising integrative approach to alleviating the increasing burden of mental and cognitive disorders through naturally derived therapeutic strategies. Full article

Chronic pain is a complex and persistent condition involving sustained nociceptive input, maladaptive neuroplastic changes, and neuroimmune interactions. Central to its pathophysiology is the dysregulation of neuromodulatory signaling pathways, including neurotransmitters (e.g., dopamine, serotonin, norepinephrine), neuropeptides (e.g., substance P, CGRP), and neurotrophic factors (e.g., BDNF), which modulate both central and peripheral sensitization mechanisms. In disorders such as fibromyalgia, altered monoaminergic transmission has been implicated in the attenuation of descending inhibitory control, thereby enhancing pain perception and reducing responsiveness to conventional therapies. Concurrently, neuroinflammation, driven by glial cell activation and cytokine release, further exacerbates neuronal excitability and reinforces maladaptive signaling loops. Recent technological advances, including transcriptomic profiling, functional neuroimaging, and single-cell RNA sequencing, have provided new insights into patient-specific patterns of neuromodulatory dysfunction, highlighting potential biomarkers for disease stratification and therapeutic targeting. These developments support the hypothesis that dysregulated neuromodulatory circuits not only underlie diverse chronic pain phenotypes but may also serve as intervention points for precision medicine. This narrative review synthesizes current evidence on the roles of neuromodulatory systems in chronic pain, focusing on synaptic plasticity, nociceptor sensitization, and neuroimmune crosstalk. By integrating preclinical findings with clinical observations, we propose a mechanistic framework for understanding pain chronification and guiding future therapeutic strategies. Harnessing neuromodulatory targets, whether pharmacologically or via neuromodulation technologies, could offer more personalized and effective approaches to chronic pain management. Full article

This narrative review explores the intricate relationship between the plasminogen activator system (PAS), comprising urokinase-type plasminogen activator (uPA) and tissue-type plasminogen activator (tPA), and a range of neuropsychiatric disorders, including depression and anxiety. By synthesizing existing preclinical and clinical evidence, we clarify the roles of uPA and tPA in the pathogenesis and potential treatments of these conditions. This narrative review emphasizes their involvement in modulating neuronal plasticity, synaptic remodeling, and neurotransmitter systems, which are pivotal in maintaining brain function and behavior. Additionally, this review highlights key mechanisms by which these activators influence the neurobiological processes underlying mood and cognitive dysfunction. Critical analysis identifies areas of consensus, such as the role of plasminogen activators in neuroinflammation and stress responses, while also addressing gaps and controversies in the literature. The findings underscore the therapeutic potential of targeting the uPA/tPA system for innovative interventions. By offering a nuanced understanding of their contributions to mood disorders, this review aims to inspire future research toward developing novel, mechanism-based treatment strategies that harness the PAS’ capacity to restore neural homeostasis and improve patient outcomes. Full article

Crowding stress is an inevitable stressor in intensive farming, yet its underlying mechanisms are still obscure, severely hindering the aquaculture industry’s healthy development. As the primary sensory and regulatory organ for stressors, the brain plays a crucial role in stress responses. In this study, the effect of crowding stress on the telencephalon (Tel) and hypothalamus (Hy) has been explored using RNA sequencing. After four weeks of crowding stress, neuroinflammation-related genes were significantly induced in both the Tel and Hy. Additionally, cell fate-related processes were markedly altered. Neurogenesis-related pathways, including the Wnt and Hedgehog signaling pathways, were significantly enriched in both regions. The apoptosis-related genes (caspase3, p53) were predominantly downregulated in the Tel (log₂Fold Change: −1.27 and −0.71, respectively), while ferroptosis-related genes (ho1, ncoa4) were specifically activated in the Hy (log₂Fold Change: 1.15 and 0.73, respectively). The synaptic plasticity-related genes (prkcg, cacna1d) were significantly downregulated in both the Tel (log₂Fold Change: −1.78 and −0.88) and Hy (log₂Fold Change: −1.99 and −1.52). Furthermore, neurotransmitter synthesis (γ-aminobutyric acid (GABA) and serotonin (5-HT)) was disrupted in the Tel, whereas growth-related hormone gene expression was markedly altered in the Hy. These findings provide novel insights into the neurobiological mechanisms of chronic crowding stress in fish, laying a foundation for developing brain-targeted strategies to enhance welfare and mitigate stress in intensive largemouth bass farming. Full article

Adenylyl cyclases (ACs) are key regulators of cyclic adenosine monophosphate (cAMP) signaling—a pathway critical for neuroregeneration, synaptic plasticity, and neuronal survival. In both the central and peripheral nervous systems, injury-induced activation of ACs promotes axonal outgrowth and functional recovery through the stimulation of protein kinase A (PKA), exchange proteins directly activated by cAMP (Epac), and cAMP-response element-binding protein (CREB). Among the various AC isoforms, calcium-sensitive AC1, AC8, and AC5, as well as bicarbonate-responsive soluble AC (sAC), have emerged as crucial mediators of neuroplasticity and axon regeneration. These isoforms coordinate diverse cellular responses—including gene transcription, cytoskeletal remodeling, and neurotransmitter release—to metabolic, synaptic, and injury-related signals. Dysregulation of AC activity has been implicated in the pathophysiology of neurodegenerative diseases such as Parkinson’s disease, Alzheimer’s disease, and amyotrophic lateral sclerosis, as well as in chronic pain syndromes. Pharmacological modulation of cAMP levels through AC activation, phosphodiesterase (PDE) inhibition, or pituitary adenylyl cyclase-activating polypeptide (PACAP) receptor signaling has shown therapeutic promise in preclinical models by enhancing neurogenesis, remyelination, and synaptic repair. Conversely, targeted inhibition of specific AC isoforms, particularly AC1, has demonstrated efficacy in reducing maladaptive plasticity and neuropathic pain. This review highlights the diverse roles of ACs in neuronal function and injury response and discusses emerging strategies for their therapeutic targeting. Full article

Astrocytes are the most abundant glial cells in the brain. They play critical roles in synapse formation and function, neurotransmitter release and uptake, the production of trophic factors, and energy supply for neuronal survival. In addition to producing proteases for amyloid-β degradation, astrocytes express various receptors, transporters, gliotransmitters, and other molecules that enable them to sense and respond to external signals. They are also implicated in amyloid-β clearance. In Alzheimer’s disease, excessive accumulation of amyloid-β induces the polarization of astrocytes into the A1 phenotype, promoting the release of inflammatory cytokines and mitochondrial reactive oxygen species, leading to alterations in astrocytic functions. Under such conditions, gliotransmitter release, glutamate neurotransmission, AMPA receptor trafficking, and both Hebbian and non-Hebbian forms of synaptic plasticity—biological activities essential for synaptic functions—are compromised. Moreover, astrocytes are essential for learning, memory, and synaptic plasticity, and alterations in their function are associated with memory deficits in Alzheimer’s disease. This review provides an overview of the current understanding of the defects in astrocytes that lead to altered synaptic functions, neuronal structural plasticity, and memory deficits in Alzheimer’s disease. Full article

Electroconvulsive therapy (ECT) remains one of the most effective interventions for treatment-resistant psychiatric disorders, particularly major depressive disorder and bipolar disorder. Despite extensive clinical and preclinical investigations, the precise neurobiological mechanisms underlying ECT’s therapeutic effects are not fully understood. This review explores the molecular and cellular pathways involved in ECT, emphasizing its impact on neurotrophic signaling, oxidative stress, apoptosis, and neuroplasticity. Evidence suggests that ECT modulates brain-derived neurotrophic factor and other neurotrophic factors, promoting synaptic plasticity and neuronal survival. Additionally, ECT influences the hypothalamic–pituitary–adrenal axis, reduces neuroinflammation, and alters neurotransmitter systems, contributing to its antidepressant effects. Recent findings also highlight the role of mitochondrial function and oxidative stress regulation in ECT-induced neural adaptation. By synthesizing current molecular insights, this review provides a comprehensive perspective on the neurobiological mechanisms of ECT, offering potential directions for future research and therapeutic advancements in brain stimulation. Full article

Despite its significance, hysteresis remains underrepresented in mainstream models of plasticity. In this work, we propose a novel framework that explicitly models hysteresis in simple one- and two-neuron models. Our models capture key feedback-dependent phenomena such as bistability, multistability, periodicity, quasi-periodicity, and chaos, offering a more accurate and general representation of neural adaptation. This opens the door to new insights in computational neuroscience and neuromorphic system design. Synaptic weights change in several contexts or mechanisms including, Bienenstock–Cooper–Munro (BCM) synaptic modification, where synaptic changes depend on the level of post-synaptic activity; homeostatic plasticity, where all of a neuron synapses simultaneously scale up or down to maintain stability; metaplasticity, or plasticity of plasticity; neuromodulation, where neurotransmitters influence synaptic weights; developmental processes, where synaptic connections are actively formed, pruned and refined; disease or injury; for example, neurological conditions can induce maladaptive synaptic changes; spike-time dependent plasticity (STDP), where changes depend on the precise timing of pre- and postsynaptic spikes; and structural plasticity, where changes in dendritic spines and axonal boutons can alter synaptic strength. The ability of synapses and neurons to change in response to activity is fundamental to learning, memory formation, and cognitive adaptation. This paper presents simple continuous and discrete neuro-modules with adapting feedback synapses which in turn are subject to feedback. The dynamics of continuous periodically driven Hopfield neural networks with adapting synapses have been investigated since the 1990s in terms of periodicity and chaotic behaviors. For the first time, one- and two-neuron models are considered as parameters are varied using a feedback mechanism which more accurately represents real-world simulation, as explained earlier. It is shown that these models are history dependent. A simple discrete two-neuron model with adapting feedback synapses is analyzed in terms of stability and bifurcation diagrams are plotted as parameters are increased and decreased. This work has the potential to improve learning algorithms, increase understanding of neural memory formation, and inform neuromorphic engineering research. Full article

Alzheimer’s disease (AD) is a neurodegenerative condition characterized by considerable cognitive decline and functional impairment, primarily due to the progressive alteration of neurons, microglia, and astrocytes. Pathological manifestations of AD include the loss of synaptic plasticity, reduction in synaptic strength by amyloid-beta, aggregation, and neurotoxicity from tau protein post-translational modifications, all contributing to the disruption of neural networks. Despite its current pharmacological treatment for AD, different approaches to treat such disease are being developed, from a microbiome perspective. The microbiome encompasses a diverse microorganism, including beneficial bacteria that create a positive impact to diminish AD pathogenesis. Growing evidence suggests that probiotic, prebiotic, synbiotic, and postbiotics can positively modulate the gut–brain axis, reducing systemic inflammation, restoring neurotransmitter balance, and improving gut health, thereby possibly mitigating AD pathogenesis. Moreover, there is paraprobiotics as the most recently developed biotherapeutic with beneficial effects. This review explores the correlation between AD and gut–brain axis as a novel biotherapeutic target. The underlying mechanism of the microbiota–gut–brain axis in AD is examined. Novel insights into the current applications as potential treatment and its limitations are highlighted. Full article

Stress and sleep share a reciprocal relationship, where chronic stress often leads to sleep disturbances that worsen neurodegenerative and psychiatric conditions. Non-neuronal cells, particularly astrocytes and microglia, play critical roles in the brain’s response to stress and the regulation of sleep. Astrocytes influence sleep architecture by regulating adenosine signaling and glymphatic clearance, both of which can be disrupted by chronic stress, leading to reduced restorative sleep. Microglia, activated under stress conditions, drive neuroinflammatory processes that further impair sleep and exacerbate brain dysfunction. Additionally, the gut–brain axis mediates interactions between stress, sleep, and inflammation, with microbial metabolites influencing neural pathways. Many of these effects converge on the disruption of synaptic processes, such as neurotransmitter balance, synaptic plasticity, and pruning, which in turn contribute to the pathophysiology of neurodegenerative and psychiatric disorders. This review explores how these cellular and systemic mechanisms contribute to stress-induced sleep disturbances and their implications for neurodegenerative and psychiatric disorders, offering insights into potential therapeutic strategies targeting non-neuronal cells and the gut–brain axis. Full article

Schizophrenia is a chronic and severe psychiatric disorder affecting approximately 1% of the global population, characterized by disrupted synaptic plasticity and brain connectivity. While substantial evidence supports its classification as a neurodevelopmental disorder, non-canonical neurodegenerative features have also been reported, with increasing attention given to astrocytic dysfunction. Overall, in this study, we explore the role of astrocytes as a structural and functional link between neurodevelopment and neurodegeneration in schizophrenia. Specifically, we examine how astrocytes contribute to forming an aberrant substrate during early neurodevelopment, potentially predisposing individuals to later neurodegeneration. Astrocytes regulate neurotransmitter homeostasis and synaptic plasticity, influencing early vulnerability and disease progression through their involvement in Ca²⁺ signaling and dopamine–glutamate interaction—key pathways implicated in schizophrenia pathophysiology. Astrocytes differentiate via nuclear factor I-A, Sox9, and Notch pathways, occurring within a neuronal environment that may already be compromised in the early stages due to the genetic factors associated with the ‘two-hits’ model of schizophrenia. As a result, astrocytes may contribute to the development of an altered neural matrix, disrupting neuronal signaling, exacerbating the dopamine–glutamate imbalance, and causing excessive synaptic pruning and demyelination. These processes may underlie both the core symptoms of schizophrenia and the increased susceptibility to cognitive decline—clinically resembling neurodegeneration but driven by a distinct, poorly understood molecular substrate. Finally, astrocytes are emerging as potential pharmacological targets for antipsychotics such as clozapine, which may modulate their function by regulating glutamate clearance, redox balance, and synaptic remodeling. Full article