Search Results (320)

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease affecting the joints, with neurogenic inflammation involving the nervous system being a hallmark of the condition. Treatments include medications such as disease-modifying antirheumatic drugs (DMARDs), corticosteroids, and biologics targeting inflammatory pathways. Yet, these treatments are not curative for RA. Heat Shock Proteins (HSPs) are molecular chaperones with immunoregulatory properties; however, their role is not yet fully understood, as these molecules may play a dual, pro- and anti-inflammatory role. In this study, we evaluated the protein expression levels of HSPs 27, 60, 70, and 90 in the synovial membrane and spinal cord of the RA rats’ model to determine their roles during the disease course, both on the neurological and immunological levels. Furthermore, HSP levels have been evaluated in the spinal cord of control and RA rats’ model after high and low doses of ketamine injection. Significant changes in Hsp60, 70, and 90 expression levels were observed only in the spinal cord of RA rats. We demonstrated that blocking N-methyl-D-aspartate receptors with ketamine can modulate spinal cord HSPs expression in RA rats and subsequently impact neurogenic inflammation and adult neurogenesis. This suggests that HSPs may be a promising target for RA treatment due to their complex immunomodulatory effects and potential interactions with the nervous system. Further research is needed to explore their therapeutic potential and develop effective interventions for RA. Full article

Schizophrenia (SZ) is a severe mental disorder associated with an array of symptoms characterized as positive, negative and cognitive dysfunctions. While SZ is a multifaceted disorder affecting several regions of the brain, altered thalamocortical systems have emerged as a leading contributor to SZ. Specifically, it has been shown that: (1) the thalamus is functionally disconnected from the prefrontal cortex (PFC) in SZ; (2) neural activity and blood flow to the PFC are greatly diminished in SZ (hypofrontality); and (3) delta oscillations are abnormally present in the PFC during the waking state in SZ. We suggest that the abnormal delta oscillations drive the other PFC signs of SZ. Specifically, decreases in energy required to maintain delta, would initiate the reduced PFC perfusion of SZ (hypofrontality), and contribute to the ‘mismatched’ thalamic and PFC activity of SZ. As SZ involves glutamate (NMDAR) hypofunction and dopamine hyperfunction, both NMDAR antagonists and dopamine agonists produce marked increases in delta oscillations in nucleus reuniens (RE) of the thalamus and its target structures, including the PFC. This would suggest that RE is a primary source for the elicitation of PFC delta activity, and the presence of delta during waking (together with associated signs) would indicate that the prefrontal cortex is disabled (or non-functional) in schizophrenia. Full article

Background/Objectives: Stroke is the second leading cause of death worldwide. There is an unmet need to manage stroke pathophysiology, including L-glutamate (L-Glu)-mediated neurotoxicity. The acai berry (Euterpe sp.) contains phytochemicals with potentially nutraceutical content. The aim of this study was to assess the ability of acai berry extracts to counter L-Glu neurotoxicity using human differentiated TE671 cells. Methods: The cytotoxicity of L-Glu and acai berry extracts was quantified using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Mitochondrial function was examined by a quantitation of cellular ATP levels, the maintenance of the mitochondrial membrane potential (MMP), and the production of reactive oxygen species (ROS). Whole-cell patch-clamp recordings monitored the activation of N-methyl-D-aspartate receptors (NMDARs). Candidate phytochemicals from acai berry extracts were modeled in silico for NMDAR binding. Results: L-Glu significantly reduced cell viability, ATP levels, the MMP, and increased cellular ROS. Generally, acai berry extracts alone were not cytotoxic, although high concentrations were detrimental to ATP production, maintenance of the MMP, and elevated ROS levels. Whole-cell patch-clamp recordings revealed that the combined addition of 300 µM L-Glu and 10 µM glycine activated currents in differentiated TE671 cells, consistent with triggering NMDAR activity. Acai berry extracts ameliorated the L-Glu-induced cytotoxicity, mitochondrial dysfunction, elevated ROS levels, and limited the NMDAR-mediated excitotoxicity (p < 0.001–0.0001). Several virtual ligands from acai berry extracts exhibited high-affinity NMDAR binding (arginine, 2,5-dihydroxybenzoic acid, threonine, protocatechuic acid, and histidine) as possible candidate receptor antagonists. Conclusions: Acai berry phytochemicals could be exploited to reduce the L-Glu-induced neurotoxicity often observed in stroke and other neurodegenerative diseases. Full article

Autoimmune encephalitis (AE) is an autoantibody-mediated central nervous system disorder with diverse neuropsychiatric and neurological manifestations, and should be considered in the differential diagnosis of acute and subacute neurological or psychiatric syndromes. In this retrospective study, we analyzed 65 patients: 54 with AE (47 antibody-positive, seven antibody-negative) and 11 antibody-positive without AE. The most frequently detected antibodies targeted N-methyl-D-aspartate receptor (NMDAR), leucine-rich glioma-inactivated protein 1 (LGI1), and contactin-associated protein-like 2 (CASPR2)—key synaptic and axonal membrane proteins involved in excitatory neurotransmission, neuronal signaling, and synaptic plasticity. Clinical presentations were heterogeneous, ranging from common neuropsychiatric, cognitive, and seizure manifestations to atypical brainstem or cerebellar features. Symptom distribution analysis further demonstrated distinct patterns among Ab-positive AE, Ab-negative AE, and Ab-positive non-AE groups, with specific symptom–antibody associations providing potential diagnostic clues. Diagnostic complexity was underscored by unusual age at onset, overlap with multiple sclerosis, cases preceded by herpes labialis, and dual-antibody detection. A subset of antibody-positive patients had alternative diagnoses, highlighting the need for careful clinical correlation and cautious interpretation of antibody results. These findings illustrate the diagnostic challenges and broad clinical spectrum of AE, emphasizing the importance of integrating serological, clinical, and imaging data to improve diagnostic accuracy and guide management. Full article

Background: Shentong Zhuyu Decoction (STZYD) is a traditional Chinese medicine formula that has shown promise in alleviating neuropathic pain (NPP), yet its central mechanisms remain unclear. Methods: We investigated the STZYD effects on NPP using network pharmacology, in vivo assays, and analytical chemistry, focusing on molecular pathways and GABAergic neuronal modulation. Results: Network pharmacology revealed 254 potential STZYD targets enriched in calcium signaling and GABAergic synapse pathways, especially the NMDAR-2B/CaMKII/CREB axis. High-dose STZYD (1.25 g·mL⁻¹) and ifenprodil (6 mg·kg⁻¹) reversed hyperalgesia and anxiety-like behaviors in spared nerve injury (SNI) mice, and microdialysis showed that STZYD and ifenprodil reduced the glutamate, D-serine, aspartate, glycine, and gamma-aminobutyric acid levels in the interpeduncular nucleus (IPN). Immunofluorescence and fiber photometry showed reduced c-Fos expression and suppressed GCaMP signals in IPN GABAergic neurons, with chemogenetic experiments confirming their role in pain modulation. Multimodal molecular biology experiments demonstrated that STZYD and ifenprodil significantly downregulated the GluN2B, p-CaMKII, and p-CREB expressions within the IPN. We identified 145 constituents in STZYD through high-resolution mass spectrometry analysis, among which 40 were absorbed into plasma and 7 were able to cross the blood–brain barrier and accumulate in the IPN. Molecular docking revealed the strong binding of licoricesaponin K2 and senkyunolide F to NMDAR-2B. Conclusions: STZYD exerts dose-dependent antinociceptive effects by modulating IPN GABAergic neuronal activity through the inhibition of the NMDAR-2B-mediated CaMKII/CREB pathway. Full article

Parkinson’s disease (PD) is a progressive neurological disorder that affects movement, causing symptoms such as tremors, stiffness, slowness, and balance problems due to the degeneration of dopamine-producing neurons in the brain. Nowadays there is no cure for PD. Alpha synuclein (α-syn) aggregates, which are a hallmark of PD, are known to induce microglial activation, specifically the detrimental M1 microglial phenotype, which contributes to neuroinflammation and disease progression. Cannabinoid receptor 2 (CB₂R) activation has been shown to counteract neuroinflammation. CB₂R is able to interact with N-methyl-D-aspartate (NMDA) receptors (NMDAR), which has also attracted attention in PD research due to its role in excitotoxicity. Here we aimed to study the interaction between CB₂R and NMDAR in a PD context in rat tissue. We observed that α-syn fibrils alter CB₂R activation and CB₂R-NMDAR heteromerization in a heterologous expression system. Furthermore, activation of CB₂R counteracted NMDAR signaling. In microglia, α-syn fibrils decreased CB₂R-NMDAR heteromer expression while increasing CB₂R signaling. Importantly, CB₂R activation counteracted the α-syn fibrils-induced increase in M1-activated microglia, while it favored the polarization of microglia to the beneficial M2 phenotype. These results reinforce the idea of using cannabinoids for treating PD, as they provide not only the anti-inflammatory effects of cannabinoids but also counteract the detrimental increase in NMDAR signaling present in this disease. 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

The Hebbian type of spike timing-dependent plasticity (STDP) with long-term potentiation and depression (LTP and LTD) plays a crucial role at layer 4 (L4) to L2/3 synapses in deprivation-induced map plasticity. In addition, plasticity at the L2/3 horizontal connection is suggested to play an additional role in map plasticity, especially for “spared whisker response potentiation.” Unimodal STDP with only LTP, or all-LTP STDP drives circuit formation at thalamocortical, as well as L4-L2/3 synapse before the critical period. Here, we first show that the L2/3 horizontal connections exhibit all-LTP STDP when axons are extending during synapse formation before the critical period. LTP-STDP induced by pre-post timing was mediated by NMDA-R because APV blocked the induction. In addition, PKA signaling was involved because PKI 6-22 blocked the induction. However, LTP-STDP induced by post-pre timing was not mediated by NMDA-R, because APV could not block its induction. Nevertheless, PKA signaling was also involved in its induction because PKI 6-22 blocked the induction. Our finding indicates that PKA signaling plays an important role in all-LTP STDP during synaptic formation at the L2/3-L2/3 connection between neighboring columns with a distinct source of Ca²⁺ influx in the developing mouse barrel cortex. Full article

Temporal lobe epilepsy (TLE) remains pharmacoresistant in 30–40% of patients. Peroxisome proliferator-activated receptor alpha (PPARα) agonists like fenofibrate exhibit anti-inflammatory and neuroprotective properties, but their region-specific effects during epileptogenesis and on behavioral comorbidities are unknown. We investigated fenofibrate (100 mg/kg, 7 days) in the lithium-pilocarpine rat model during the latent phase. Fenofibrate (1) reduced anxiety-like behaviors and improved exploratory deficits; (2) decreased plasma short-chain fatty acids (butyric, pentanoic, hexanoic acids); (3) exerted region-specific modulation of glutamate receptors: restored N-methyl-D-aspartate receptor (NMDAR)/α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) subunit gene expression in temporal cortex but failed to reverse and further exacerbated the downregulation of AMPAR subunits in the dorsal hippocampus; (4) prevented the upregulation of cortical neuroinflammation markers (reduced Nlrp3, Il1rn); and (5) enhanced the A2 astrocyte marker Ptx3 in the hippocampus while reducing the M2 microglial marker Arg1 in the temporal cortex. No effects on astrogliosis (Gfap), microgliosis (Aif1), or trophic factors (Bdnf, Tgfb1) were observed. This first comprehensive study demonstrates that fenofibrate differentially modulates neuroinflammation and synaptic plasticity across brain regions during epileptogenesis, providing behavioral benefits but highlighting potential hippocampal drawbacks. Its PPARα-mediated actions support further investigation as a complementary strategy for TLE, pending optimization of dosing/timing to mitigate regional disparities. Full article

N-methyl-D-aspartate receptors (NMDARs) are ionotropic glutamate channels that play a pivotal role in brain development and the regulation of learning and memory processes. De novo pathogenic variants in four genes encoding NMDA receptor subunits (GRIN1, GRIN2A, GRIN2B, and GRIN2D) have been implicated in a broad spectrum of neurodevelopmental disorders, including developmental delay, intellectual disability, autism spectrum disorders, epilepsy, and movement disorders. Mutations in the GRIN1 and GRIN2B genes, which encode the GluN1 and GluN2B subunits, respectively, are strongly associated with malformations of cortical development, including diffuse dysgyria, bilateral polymicrogyria, hippocampal dysplasia, corpus callosum hypoplasia, and other findings such as ventricular enlargement and basal ganglia abnormalities. Conversely, GRIN2A mutations are associated with heterogeneous and less specific neuroimaging patterns. We reviewed the existing literature on the neuroradiological features associated with GRIN gene mutations, also providing pictorial representations from our patient cohort. The analysis revealed a more consistent association of malformations of cortical development with GRIN1 and GRIN2B variants, likely reflecting the critical role of these genes in neuronal migration and proper development of cortical structures. In comparison, GRIN2A mutations are associated with milder brain abnormalities. An integrated assessment of neuroimaging patterns and GRIN gene variants provides valuable insights for differential diagnosis and supports targeted genetic screening in patients presenting with epileptic encephalopathy, global developmental delay, and autism spectrum disorders. Full article

Cardiotonic steroids (CTS), including the endogenous compound ouabain, modulate neuronal Na/K-ATPase (NKA) activity in a concentration-dependent manner, affecting neuronal survival and function. While high concentrations of ouabain are neurotoxic, endogenous levels of 0.1–1 nM exert neuroprotective effects and influence intracellular signaling. However, the effects of physiologically relevant ouabain concentrations on excitatory synaptic transmission remain unclear. In this study, we examined how 1 nM ouabain affects synaptic responses in rat hippocampal CA1 neurons. Using whole-cell patch-clamp recordings of evoked excitatory postsynaptic currents (EPSCs) and extracellular recordings of field excitatory postsynaptic potentials (fEPSPs), we found that ouabain enhances excitatory synaptic transmission, increasing EPSC amplitude and fEPSP slope by 35–50%. This effect was independent of NMDA receptor (NMDAR) activity. Ouabain reduced the magnitude of NMDAR-dependent long-term potentiation (LTP), but still augmented fEPSPs when applied after LTP induction. This implies separate additive mechanisms. These observations exhibit that ouabain, at concentrations corresponding to endogenous levels, facilitates basal excitatory synaptic transmission while partially suppressing LTP. We propose that ouabain exerts dual modulatory effects in hippocampal networks via distinct synaptic mechanisms. Full article

Forty per cent of major depression patients are resistant to antidepressant medication. Thus, it is necessary to search for alternative treatments. Melatonin (N-acetyl-5-hydroxytryptamine) enhances neurogenesis and neuronal survival in the adult mouse hippocampal dentate gyrus. Additionally, melatonin stimulates the activity of Ca²⁺/Calmodulin-dependent Kinase II (CaMKII), promoting dendrite formation and neurogenic processes in human olfactory neuronal precursors and rat organotypic cultures. Similarly, ketamine, an N-methyl-D-aspartate receptor (NMDAR) antagonist, modulates CaMKII activity. Importantly, co-treatment of low doses of ketamine (10⁻⁷ M) in combination with melatonin (10⁻⁷ M) produces additive effects on neurogenic responses in olfactory neuronal precursors. Importantly, enhanced neurogenic responses are produced by conventional antidepressants like ISSRs. The goal of this study was to investigate whether hippocampal CaMKII participates in the signaling pathway elicited by combining doses of melatonin with ketamine acutely administered to mice, 30 min before being subjected to the forced swimming test. The results showed that melatonin, in conjunction with ketamine, significantly enhances CaMKII activation and changes its subcellular distribution in the dentate gyrus of the hippocampus. Remarkably, melatonin causes nuclear translocation of the active form of CaMKII. Luzindole, a non-selective MT₁ and MT₂ receptor antagonist, abolished these effects, suggesting that CaMKII is downstream of the melatonin receptor pathway that causes the antidepressant-like effects. These findings provide molecular insights into the combined effects of melatonin and ketamine on neuronal plasticity-related signaling pathways and pave the way for combating depression using combination therapy. Full article

Background: We recently reported sex-dependent impairment in cognitive functions in male and female mice exposed for 24 h, 48 h or 15 days to 2G hypergravity (HG). Methods: In the present study, we investigated brain functional correlates by analyzing synaptic activity and plasticity in the CA1 area of the hippocampus in both genders of mice previously exposed to 2G for the same duration. This was assessed by electrophysiological extracellular recordings in ex vivo slice preparations. Results: Basal synaptic transmission and glutamate release were unchanged regardless of HG duration. However, plasticity was altered in a sex- and time-specific manner. In males, long-term potentiation (LTP) induced by strong high-frequency stimulation and NMDA receptor (NMDAr) activation was reduced by 26% after 24 h of exposure but recovered at later timepoints. This deficit was reversed by D-serine or glycine, suggesting decreased activation at the NMDAr co-agonist site. In females, LTP deficits (23%) were found only after 15 days following mild theta burst stimulation and were not reversed by D-serine. Long-term depression (LTD) was unaffected in both sexes. Conclusions: This study highlights, for the first time, sex-dependent divergence in the CA1 hippocampal plasticity timeline following 2G exposure. The synaptic changes depend on exposure duration and the stimulation protocol and could underlie the previously observed cognitive deficits. Full article

Background: The N-methyl-d-aspartate receptor (NMDA-R) is a glutamate ionotropic receptor in the brain that is crucial for synaptic plasticity, which underlies learning and memory formation. Dysfunction of NMDA receptors is implicated in various neurological diseases due to their roles in both normal cognition and excitotoxicity. However, their dynamics are challenging to capture accurately due to their high complexity and non-linear behavior. Methods: This article presents the elaboration and calibration of experimentally constrained computational models of GluN1/GluN2A NMDA-R dynamics: (1) a nine-state kinetic model optimized to replicate experimental data and (2) a computationally efficient look-up table model capable of replicating the dynamics of the nine-state kinetic model with a highly reduced footprint. Determination of the kinetic model’s parameter values was performed using the particle swarm optimization algorithm. The optimized kinetic model was then used to generate a rich input–output dataset to train the look-up table synapse model and estimate its coefficients. Results: Optimization produced a kinetic model capable of accurately reproducing experimentally found results such as frequency-dependent potentiation and the temporal response due to synaptic release of glutamate. Furthermore, the look-up table synapse model was able to closely mimic the dynamics of the optimized kinetic model. Conclusions: The results obtained with both models indicate that they constitute accurate alternatives for faithfully reproducing the dynamics of NMDA-Rs. High computational efficiency is also achieved with the use of the look-up table synapse model, making this implementation an ideal option for inclusion in large-scale neuronal models. Full article

Glutamate and dopamine receptors play a crucial role in regulating synaptic plasticity throughout the sleep–wake cycle. These receptors form various heterocomplexes in synaptic areas; however, the role of this protein interactome in sleep–wake cycles remains unclear. Co-immunoprecipitation experiments were conducted to observe the complexation of the NMDA glutamate receptor (NMDAR) subunits GluN2A and GluN2B, metabotropic glutamate receptors mGluR1/5, and dopamine receptors (D1R and D2R) with the scaffold protein Homer in the synaptic membranes of the hippocampus after six hours of sleep deprivation (SD) in rats. Our findings indicate that the level of Homer in the GluN2A/mGluR1/D1R interactome decreased during SD, while the content of Homer remained unchanged in the GluN2B/mGluR1/D2R heterocomplex. Moreover, Homer immunoprecipitated a reduced amount of inositol trisphosphate receptor (IP3R) in the microsomal and synaptic fractions, confirming the dissociation of the ternary supercomplex Homer/mGluR1/IP3R during SD. Additionally, our findings indicate that SD increases the synaptic content of the AMPA receptor (AMPAR) subunit GluA1. Unlike AMPAR, NMDAR subunits in synaptic membranes do not undergo significant changes. Furthermore, the G-to-F actin ratio decreases during SD. Changes in the assembly of actin filaments occur due to the dephosphorylation of cofilin. These results suggest that SD causes the dissociation of the GluN2A/mGluR1/D1R/Homer/IP3R heterocomplex in synaptic and endoplasmic membranes. Full article