Search Results (1,159)

Background/Objectives: Magnesium (Mg) is essential for neuronal maturation, yet its role in human cortical development remains poorly defined. Here, we investigated the effects of physiological (1 mM) and elevated (5 mM) concentrations of MgSO₄ and magnesium pidolate (MgPid) on human brain organoids co-cultured with an in vitro blood–brain barrier (BBB) model. Methods: Human brain organoids derived from induced pluripotent stem cells were co-cultured with an in vitro BBB system and treated for 4 days with either MgSO₄ or MgPid at physiological and elevated concentrations. Cortical organization was assessed by transmission electron microscopy and immunofluorescence analysis. Western blotting for neurotransmitter receptors and Mg transporters, quantification of intraorganoid Mg²⁺ levels, ELISA-based measurement of GABA and dopamine, and analysis of glutamate were performed. Results: High Mg exposure enhanced cortical stratification and neuronal organization, as shown by the localization of CTIP2 in the outermost layer and TBR2 in the inner layer, together with ultrastructural features consistent with advanced differentiation. Elevated Mg increased intraorganoid Mg²⁺ levels without altering Mg transporter abundance and selectively modulated neurotransmitter receptor expression: NMDA-R levels were reduced by MgPid, whereas GABA_A-R and GABA_B-R were upregulated, particularly in response to MgPid. Levels of glutamate, GABA, and dopamine remained unchanged. Conclusions: These findings identify Mg, especially in the form of MgPid, as a modulator of cortical architecture and inhibitory–excitatory receptor balance in human organoids, supporting its potential relevance for neurodevelopmental regulation and Mg-based therapeutic strategies. These results also support organoids as human-relevant, animal-free tools for neuroscience and neuropharmacological research. Full article

Zika virus (ZIKV) infection is associated with severe neurodevelopmental disorders. However, the molecular mechanisms involved in the imbalance of excitatory and inhibitory neurotransmitter systems remain poorly understood. In this study, we evaluated the expression of components of the GABA–glutamate system in neonatal BALB/c mice inoculated with ZIKV at 10 days post-infection (dpi). Analysis of GABA-A and NMDA receptors revealed widespread downregulation of GABA-A and NMDA receptor subunits in the cerebral cortex and cerebellum, except for the alpha-5 and epsilon GABA-A subunits, which were upregulated in the cerebellum. Infected mice also showed increased GABA immunoreactivity and glutamate loss. The enzymes involved in neurotransmitter synthesis or transport confirmed these findings when assessed by qRT-PCR or Western blot, revealing increased expression of GAD-65/67, accompanied by a loss of glutamate dehydrogenase (GLUD) in the cerebral cortex and cerebellum, along with decreased expression of the glutamate transporter (VGLUT) in the cerebral cortex. These findings suggest that GABA synthesis increases during ZIKV infection, creating a neurochemical environment that favors viral replication and contributes to the migration and synaptic defects observed in congenital Zika syndrome. Full article

Primary neuronal cultures from the brain are critical for investigating disease-specific cellular and molecular mechanisms in mouse models. Current methods for obtaining primary cultures require embryonic brains that are affected by embryonic lethality and genotypic characterization in severe disease models such as sickle cell disease (SCD). Furthermore, these neuronal cultures require about 14 days in vitro (DIVs) for neurite outgrowth to mature. We adapted and optimized a relatively simplified and reproducible method using brains from postnatal day 1 mouse pups for isolating and culturing hippocampal and cortical neurons. This approach produces viable neurons that attach, extend neurites, and express key synaptic markers by 7 DIV and also minimizes glial outgrowth. We successfully applied this approach to isolating and culturing hippocampal and cortical neurons from the brains of one-day-old (P1) pups of humanized transgenic homozygous BERK sickle cell and control mice. Morphological observations at 3, 7, and 14 DIVs demonstrated robust neuronal attachment, neurite outgrowth, and overall structural development in both male and female hippocampal and cortical neurons. Neurons in culture expressed key markers including neuronal nuclear protein (NeuN/Rbfox3), neurofilament 200 (NF200), microtubule-associated protein 2 (MAP2), vesicular glutamate transporter 1 (VGLUT1), postsynaptic density protein 95 (PSD 95), and glutamate N-methyl-D-aspartate receptor subunit 2B (GluN2B). Notably, male SCD hippocampal neurons evinced a higher density of PSD 95 puncta on dendritic spines compared to controls on 7 as well as 14 DIVs. Incubation of male hippocampal neurons in a sickle cell-like microenvironment with TNF-α and heme further increased the density of PSD 95 puncta and colocalization of GluN2B with PSD 95, supporting the utility of this culture system for examining disease-relevant structural and molecular responses. This optimized culture system provides a simplified and reproducible platform to investigate the mechanisms involving neuronal dysfunction in challenging mouse models of brain disorders. Full article

Background/Objectives: Bipolar disorder affects about 40 million people worldwide, and the greatest burden of the disease is associated with depressive episodes. About 25% of patients experience drug-resistant depression, in which standard treatment turns out to be insufficient, and monotherapy often does not bring full remission. Despite the use of second-generation antipsychotics, the effectiveness of therapy in TRBD remains limited, which necessitates rational polypharmacotherapy and augmentation strategies. The paper discusses the receptor mechanisms of drug combination, current therapeutic regimens and new interventions such as ketamine acting on the glutamate anergic system. The aim was to synthetically compare the efficacy and safety of available augmentation strategies and polypharmacotherapy. Methods: The material consists of published clinical, observational and randomized trials on pharmacotherapy of drug-resistant bipolar depression, including atypical neuroleptics, ketamine, pramipexole, modafinil, lamotrigine, celecoxib and memantine. The authors analyze receptor mechanisms, neurobiological data and clinical trial results, comparing them with current definitions of TRBD according to ISBD and CINP. Biomarker data, such as the Systemic Immune-Inflammation Index, and the results of neuroimaging and metabolomic studies were also used in the work. Results: The analysis showed that atypical neuroleptics showed limited efficacy and high rates of side effects, while ketamine has the fastest and most pronounced antidepressant effect with a low risk of phase change. Pramipexole has shown promise in terms of long-term efficacy, but its use reduces the high risk of induction of mania and impulse control disorders. Celecoxib as an anti-inflammatory therapy significantly increased response and remission rates compared to escitalopram alone, and memantine showed only an early, short-term antidepressant effect. The results highlight that TRBD requires targeted polypharmacotherapy, with the most promising directions being glutamatergic modulation and anti-inflammatory therapies. Conclusions: Drug-resistant bipolar depression requires a departure from classical monotherapy in favor of rational, mechanistically justified polypharmacotherapy, targeting complex monoaminergic, glutamatergic and neuroinflammatory disorders. Available data indicate that ketamine has the greatest clinical potential among the current strategies, characterized by a rapid onset of action and a favorable safety profile compared to atypical neuroleptics or dopamine agonists. Modulation of inflammatory processes with the use of celecoxib also has promising results, which highlights the importance of biomarkers and personalization of therapy. However, further, large, and well-designed studies are needed to unambiguously determine optimal treatment strategies for TRBD and to verify the effectiveness of new pharmacological interventions. Full article

Pregabalin (PGB) exerts its therapeutic effects by binding to the α₂δ auxiliary subunits of voltage-gated calcium channels and modulates synaptic transmission in the brain. However, its influence on cerebellar parallel fiber–Purkinje cell (PF–PC) synaptic transmission remains unclear. In the present study, we investigated the effects of PGB on PF–PC synaptic transmission using whole-cell patch-clamp recording, glutamate fluorescence imaging, immunohistochemistry, co-immunoprecipitation, Western blotting, and pharmacological approaches. Micro-application of PGB to the cerebellar molecular layer induced a concentration-dependent inhibition of PF–PC excitatory postsynaptic currents (EPSCs), accompanied by an increased paired-pulse ratio. The inhibitory effect of PGB on PF–PC EPSCs was abolished by extracellular blockade of N-methyl-D-aspartate receptors (NMDAR) or their GluN2A subtype, as well as by disruption of α₂δ-1–NMDAR complexes, but not by intracellular NMDAR inhibition. Glutamate sensor imaging further showed that PGB markedly reduced the fluorescence intensity of glutamate release evoked by PF stimulation. In the presence of tetrodotoxin (TTX) and a gamma-aminobutyric acid type A (GABAA) receptor antagonist, PGB reduced the frequency of miniature excitatory postsynaptic currents (mEPSCs) without affecting their amplitude. The PGB-induced reduction in mEPSC frequency was fully abolished by extracellular blockade of GluN2A-containing NMDARs or disruption of α₂δ-1–NMDAR complexes. Similarly, the inhibitory effects of PGB on PF–PC EPSCs and mEPSCs were eliminated by extracellular PKA inhibition, but not by intracellular protein kinase A (PKA) inhibition. Western blot analysis showed that PGB significantly increased PKA phosphorylation in the molecular layer of the cerebellar cortex. Immunoreactivity for GluN2A and α₂δ-1 subunits was colocalized within the molecular layer and abundantly distributed around the dendrites and somata of PCs. Co-immunoprecipitation further verified that α₂δ-1 was co-precipitated with GluN1 in cerebellar molecular layer tissue samples. The results indicate that PGB depresses glutamate release from parallel-fiber terminals in the mouse cerebellar cortex through the presynaptic α₂δ-1-coupled GluN2A-containing NMDAR/PKA signaling pathway, thereby attenuating PF–PC synaptic transmission. Full article

Amino acids are organic compounds that serve as the fundamental building blocks of proteins and are additionally responsible for a multitude of other biological functions. This review synthesizes recent evidence elucidating that amino acids function as vital players in nitrogen transport, stress defense, and perhaps most intriguingly as signaling molecules. For example, glutamate triggers calcium signals through GLR receptors to guide root growth and pollen tubes. Others, like proline and glutathione, protect cells from drought, salt, and oxidative damage. Aromatic and sulfur-containing amino acids also feed into the production of hormones (auxin, ethylene) and a wide range of defense compounds. Beyond metabolism, we highlighted how plants sense amino acid status via ancient sensors such as PII and the TOR pathway, which fine-tune growth and resource allocation. Understanding this hidden side of amino acids opens new doors for agriculture. We discussed how these insights could lead to smarter biostimulants, gene-edited crops with better nutrient efficiency, and nano-based delivery systems. In short, amino acids are not just food for plants—they are signals, shields, and switches that shape how plants grow and cope with stress. Full article

Oxytocin’s capacity to affect the glial cell functions is increasingly recognized. We previously reported that oxytocin could cause both excitation and inhibition of Ca²⁺ signals and glutamate release in the processes of adult rodent astrocytes. Our purpose here was to investigate oxytocin receptor expression and oxytocin effects in astrocytes. In primary cortical astrocytes, we assessed the presence of oxytocin receptors by confocal imaging, and the effects of oxytocin receptor activation on intracellular Ca²⁺ signals and glutamate release. We found that oxytocin receptors are expressed in both the soma and processes of astrocytes; oxytocin at nanomolar concentrations could induce dual responses in astrocytes, namely facilitation and inhibition of Ca²⁺ signals and glutamate release; the oxytocin facilitatory and inhibitory effects were duplicated by the biased agonists carbetocin and atosiban, respectively; and the facilitatory and the inhibitory effect were dependent on activation of a G_q and a G_i pathway, respectively. It is concluded that oxytocin effects in astrocytes could duplicate the effects in processes prepared from astrocytes matured in neuron-astrocyte networks, substantiating the use of astrocytes to study astrocytic oxytocin molecular signaling. Full article

Excitotoxicity is one of the factors that participates in neurodegeneration, impairing neuronal and glial cells’ function, and leading to the development of chronic neurodegenerative diseases. The main mechanism of action lies in the overstimulation of excitatory receptors, especially the NMDA (N-methyl-D-aspartic acid) receptor, by glutamate, which promotes a massive influx of Ca²⁺ that is not sufficiently buffered by the intracellular machinery, or not released by mechanisms such as Ca²⁺ ATPase and plasma membrane Ca²⁺/Na⁺ exchanger promoting, among other toxic effects, mitochondrial damage and an increase in reactive oxygen species (ROS). Notably, many cases reported of long COVID-19 describe significant brain alterations and neuropsychiatric disorders, including delirium, depression, etc., and patients required increased use of antidepressant or anxiolytic drugs, for example. In addition, emerging evidence links neurodegeneration as a potential long-term sequelae associated with an increased number of patients with cognitive disorders. This review analyzes data from the literature regarding brain alterations associated with post-COVID-19 syndrome and explores a potential link to the excitotoxicity pathways, due to its participation in neurodegeneration by homeostatic failure, and it is clearly present in various brain conditions, such as Alzheimer’s and Parkinson’s diseases. Full article

Dietary arachidonic acid (ARA) is essential for aquatic animal growth and health, but studies in bivalves are still limited. Here, microcapsule diets with increasing ARA concentrations (ARA1-6 groups: 0.35, 3.01, 5.25, 6.88, 8.69, and 10.27 mg g⁻¹ dry matter) were prepared by spray drying, and clam Sinonovacula constricta juveniles were fed these diets for 14 days. Results showed that dietary ARA concentrations did not significantly affect clams’ survival, weight gain, and shell length gain rates. The clams in the ARA6 group had significantly higher crude lipid content than those in the other microcapsule groups. The ARA concentrations in the clams increased with higher dietary ARA, while n-3 polyunsaturated fatty acids (PUFAs) and eicosapentaenoic acid (EPA) concentrations decreased. The mRNA levels of cyclooxygenase 2 and 5-lipoxygenase type 2 were significantly higher in the ARA5 and ARA6 groups compared to the ARA1 group. The mRNA levels of 5-lipoxygenase type 3, toll-like receptor 4, and nuclear factor-kappa b p50 (nfκb p50) were significantly higher in the ARA6 group compared to the ARA1 group. As dietary ARA concentrations increased, the mRNA levels of glutamate–cysteine ligase catalytic subunit and glutathione S-transferase, along with malondialdehyde (MDA) content, increased in the clams. Additionally, the superoxide dismutase and catalase activities in the ARA5 and ARA6 groups were significantly higher than those in the ARA1 and ARA2 groups. Clam ARA content, acting as a central node, showed very strong positive correlations with MDA and cyclooxygenase 2, and very strong negative correlations with EPA and the n-3/n-6 PUFA ratio. Our results revealed that high dietary ARA, while not affecting growth, reduced the n-3/n-6 PUFA ratio and induced a response characterized by the upregulation of NF-κB and Nrf2 pathway genes in S. constricta. Full article

Hepatocellular carcinoma (HCC) is the most common type of liver cancer that is mostly preceded by cirrhosis, with a high mortality rate. Therefore, diagnosis is critical in the early stages. In this study, we explored the liver expression of metabotropic glutamate receptor 3 (mGluR3), a group II mGluR, during the progression from fibrosis to cirrhosis and, ultimately, to HCC induced by diethylnitrosamine (DEN) in rats. We found that mRNA expression of mGluR3 (Grm3) was upregulated in HCC, while the protein level was significantly increased from the cirrhosis stage, and even more in HCC. Grm3 correlated with interleukin-6 (Il6) and transforming growth factor-β (Tgfb) mRNA expression. Furthermore, serum and intrahepatic glutamate concentrations were augmented in HCC. Immunohistochemical analysis revealed that mGluR3 is expressed in hepatocytes and non-parenchymal cells (endothelial cells and macrophages), and we observed a positive signal in the cytoplasmic membrane, cytoplasm, and nuclei of tumor and non-tumor cells. We confirmed that normal hepatocytes (C9 cell line) express low levels of mGluR3 protein and HCC-derived cells (HepG2) express high levels of this receptor. Using HepG2 cells, we observed that mGluR3 activation by glutamate and the group II-selective agonist LY354740 treatments were functional, as both inhibited cAMP generation induced by forskolin and increased cellular viability with no effect on dead cells. These results showed that mGluR3 is differentially expressed throughout the progression of liver pathologies, is associated with the inflammatory environment, and plays a role in HCC cell survival, with potential utility as an early biomarker and therapeutic target. Full article

Sensorineural hearing loss (SNHL) can result from genetic mutations, excessive noise exposure, ototoxic drugs, and aging. Glutamate excitotoxicity is one of the underlying mechanisms of SNHL. However, the specific roles of different glutamate receptor subtypes in normal signaling and excitotoxic damage remain unclear. Addressing these questions requires relevant experimental models. This review compares existing protocols for the isolation and cultivation of primary spiral ganglion cells. It also evaluates the utility of this model for studying glutamatergic transmission and glutamate-induced excitotoxicity. A literature search was conducted in PubMed, Scopus, Google Scholar, and Web of Science. We identified 16 relevant English-language articles published since 1990, when the model was first used to study glutamatergic signaling. Our analysis reveals significant heterogeneity in spiral ganglion cell isolation protocols and culture conditions. We highlight major differences in glutamate concentrations and exposure times used to model excitotoxicity. The most significant limitation of this model is the loss of the native microenvironment of auditory neurons, including their dendritic and axonal contacts. Nevertheless, primary spiral ganglion cells serve as a suitable in vitro model for investigating auditory neuron function and pathology. The number of neurons and neurite length serve as reliable indicators of otoprotective effects under conditions of glutamate excitotoxicity. Based on an analysis of the key stages of primary SGC culture establishment, this study proposes approaches to overcome limitations and improve the practice of using this model. A better understanding of the function of glutamate receptors of SGNs and the mechanisms behind glutamate excitotoxicity could help us to develop new treatments for SNHL. This review serves as a practical guide for researchers implementing or optimizing primary SGC cultures. Full article

Breast cancer brain metastasis (BCBM) affects up to 30% of patients with metastatic disease and carries a median survival of only 4–18 months. Emerging evidence reveals that BCBM cells are not passive survivors, but active participants that hijack core neurotransmitter networks, GABA (gamma-aminobutyric acid) and glutamate, to fuel their growth. BCBM, particularly triple-negative breast cancer (TNBC), frequently switch to a GABAergic mode utilizing brain-derived GABA as an oncometabolite. In parallel, BCBM cells can also form direct synapses with neurons, tapping into excitatory input through glutamatergic receptors to drive tumor cell proliferation and survival. Concurrently, reprogrammed astrocytes establish gap junctions, secrete growth factors, and provide metabolic support. Together, tumor cells, neurons, and astrocytes form a pathological partnership locked in feedback loops sustaining metastatic progression. This review focuses on the unique mechanisms employed by distinct breast cancer subtypes and maps the metastatic progression from pre-metastatic to mature brain metastatic niche formation of BCBM. We highlight opportunities to repurpose neurological drugs to disrupt these communication axes. Full article

Tumor-associated Tie2-expressing monocytes/macrophages (TEMs) have been implicated in promoting angiogenesis and metastasis in colorectal cancer (CRC), yet the molecular mechanisms linking TEMs infiltration to tumor metastasis and progression remain incompletely defined. This study investigated the distribution of TEMs in CRC and their association with gene expression profiles, microvessel density (MVD), and clinical outcomes. Immunohistochemistry on 30 formalin-fixed paraffin-embedded (FFPE) primary CRC samples revealed that TEMs, which characteristically express tyrosine kinase with immunoglobulin and epidermal growth factor homology domains 2 (Tie2) receptor and CD14, preferentially localize to perivascular regions and are associated with higher histological grade, tumor size, lymph node metastasis, and increased MVD. However, Tie2⁻/CD14⁺ macrophages and CD68⁺ tumor-associated macrophages (TAMs) showed uniform stromal distribution. Gene set enrichment analysis (GSEA) of in silico transcriptomic datasets of metastatic CRC (mCRC) identified enrichment of pathways related to cell–cell recognition, calcium signaling, transcription regulation, and metalloexopeptidase activity in Tie2⁺/CD14⁺ tumors. Subsequent qRT-PCR validation on FFPE primary CRC samples confirmed significant upregulation of C-C chemokine receptor 7 (CCR7), platelet-derived growth factor A (PDGFRA), CBP/p300-interacting transactivator with glutamic acid/aspartic acid-rich carboxyl-terminal domain 2 (CITED2), and carboxypeptidase E (CPE) in TEMs⁺ regions. Notably, angiopoietin1 (Ang1), but not angiopoietin2 (Ang2), was significantly elevated in TEMs⁺ primary tumors. Kaplan–Meier analysis on 1336 CRC patients indicated that high expression of CITED2, CPE, and Ang2 is associated with reduced overall survival. Collectively, these findings suggest that TEM infiltration is linked to transcriptional regulation, biological processes, and enzymatic programs in CRC, potentially contributing to tumor progression and poor prognosis, and highlight CCR7, PDGFRA, CITED2, CPE, and Ang1 as candidate biomarkers for further mechanistic exploration. Full article

Kynurenic acid (KYNA), a metabolite of the L-kynurenine pathway of L-tryptophan degradation, is an endogenous blocker of glutamate ionotropic excitatory amino acid (EAA) receptors and nicotinic acetylcholine receptors (nAChRs). KYNA plays a significant role in various neuropsychiatric disorders and the aging process. Some researchers have suggested that KYNA may contribute to memory impairment. In this study, we examined the impact of L-kynurenine (a KYNA substrate) and the anti-dementia drugs D-cycloserine and Cerebrolysin on kynurenine aminotransferase (KAT) activity, an enzyme forming KYNA, in liver homogenates of Helix pomatia snails. Furthermore, a memory model was established using these snails, wherein tentacle shortening served as an indicator of learning activity. In vitro experiments on Helix pomatia demonstrated the significant impact of L-kynurenine and anti-dementia drugs on KYNA synthesis. KYNA levels increased significantly in the presence of L-kynurenine in liver homogenate. However, KYNA formation decreased when anti-dementia drugs, including Cerebrolysin or D-cycloserine, were administered to the snails’ liver homogenate. L-kynurenine has been shown to impair the learning process in vivo in snails, but an anti-dementia drug has been demonstrated to reverse this effect. Significant inhibition of tentacle lowering was observed in response to L-kynurenine treatment, which corresponded with elevated KYNA levels in the central nervous system. Administering D-cycloserine or Cerebrolysin alongside L-kynurenine reversed its effects. The Helix pomatia memory model is a valuable tool for studying learning and memory formation in various conditions and in the presence of different pharmacological agents. A drug or natural extract that blocks KYNA synthesis has the ability to increase tentacle lowering and could be considered an anti-dementia agent. Furthermore, this metabolite may also protect against aging and delay damage to the central nervous system related to memory. Full article

Polysialic acid (PSA), a highly negatively charged glycan attached mainly to the neural cell adhesion molecule (NCAM), is emerging as a critical but underrecognized extracellular regulator of glutamatergic neurotransmission. While previous literature has focused on PSA’s developmental roles, increasing evidence indicates that PSA–NCAM also contributes to synaptic plasticity mechanisms in the mature brain. This review integrates evidence from structural biophysics, single-channel electrophysiology, and disease models to explain how PSA modulates glutamate receptor gating to control learning and memory. We synthesize findings from biochemical reconstitution, electrophysiological recordings, and in vivo studies to show that PSA can modulate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor open probability, burst duration, and cooperative gating without affecting conductance, thereby promoting long-term potentiation. Conversely, PSA selectively suppresses GluN2B-containing extrasynaptic N-methyl D-Aspartate (NMDA) receptor activity by lowering open probability and calcium influx, maintaining an optimal balance between potentiation and depression while providing neuroprotection. Disruption of PSA–NCAM signaling in developmental and disease models, including prenatal cannabinoid exposure and neurodegeneration, produces cognitive deficits reversible by PSA restoration. Notably, much of the current evidence derives from in vitro systems, with relatively few studies conducted in vivo, and studies employing PSA mimetics mostly, which should be considered when interpreting physiological relevance. Collectively, the available evidence suggests that PSA functions as an extracellular modulator linking synaptic glycans to glutamate receptor regulation and plasticity related signaling pathways, highlighting the potential importance of extracellular glycan mechanisms in the control of synaptic function. Full article