Search Results (1,056)

The ability of the neuropeptide oxytocin to affect glial cell function is receiving increasing attention. We previously reported that oxytocin at a low nanomolar concentration could inhibit both astrocytic Ca²⁺ signals and glutamate release. Here, we investigate the ability of oxytocin receptors to couple both inhibitory and stimulatory pathways in astrocytes, as already reported in neurons. We assessed the effects of oxytocin at concentrations ranging from low to high in the nanomolar range on intracellular Ca²⁺ signals and on the glutamate release in astrocyte processes freshly prepared from the striatum of adult rats. Our main findings are as follows: oxytocin could induce dual responses in astrocyte processes, namely the inhibition and facilitation of both Ca²⁺ signals and glutamate release; the inhibitory and the facilitatory response appeared dependent on activation of the G_i and the G_q pathway, respectively; both inhibitory and facilitatory responses were evoked at the same nanomolar oxytocin concentrations; and the biased agonists atosiban and carbetocin could duplicate oxytocin’s inhibitory and facilitatory response, respectively. In conclusion, due to the coupling of striatal astrocytic oxytocin receptors to different transduction pathways and the dual effects on Ca²⁺ signals and glutamate release, oxytocin could also play a crucial role in neuron–astrocyte bi-directional communication through a subtle regulation of striatal glutamatergic synapses. Therefore, astrocytic oxytocin receptors may offer pharmacological targets to regulate glutamatergic striatal transmission, which is potentially useful in neuropsychiatric disorders and in neurodegenerative diseases. Full article

Status epilepticus occurs when a seizure lasts more than five minutes or when multiple seizures occur with incomplete return to baseline. SE induces a myriad of pathological changes involving synaptic and extra-synaptic factors. The transition from a self-limiting seizure to a self-sustaining one is established by maladaptive receptor trafficking, whereby GABA_A receptors are progressively endocytosed while glutamatergic receptors (NMDA and AMPA) are transported to the synaptic membrane, causing excitotoxicity and alteration in glutamate-dependent downstream signaling. The subsequent influx of Ca²⁺ exposes neurons to increased levels of [Ca²⁺]i, which overwhelms mitochondrial buffering, resulting in irreversible mitochondrial membrane depolarization and mitochondrial injury. Oxidative stress resulting from mitochondrial leakage and increased production of reactive oxygen species activates the inflammasome and induces a damage-associated molecular pattern. Neuroinflammation perpetuates oxidative stress and exacerbates mitochondrial injury, thereby jeopardizing mitochondrial energy supply in a state of accelerated ATP consumption. Additionally, Ca²⁺ overload can directly damage neurons by activating enzymes involved in the breakdown of proteins, phospholipids, and nucleic acids. The cumulative effect of these effector pathways is neuronal injury and neuronal death. Surviving neurons undergo long-term alterations that serve as a substrate for epileptogenesis. This review highlights the multifaceted mechanisms underlying SE self-sustainability, pharmacoresistance, and subsequent epileptogenesis. 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/Objectives: Traumatic brain injury is one of the leading causes of death and disability. When traumatic brain injury is repeated over time, it can lead to the development of Chronic Traumatic Encephalopathy, a chronic neurodegenerative disease commonly observed in individuals who engage in contact sports or military personnel involved in activities with a high risk of repeated head trauma. At autopsy, the examination of the brain reveals regional atrophy, corresponding to high concentrations of glutamate receptors. Microscopically, the primary findings are the deposition of neurofibrillary tangles and neuropil threads. The aim of this study is to highlight the clinical and histopathological characteristics of Chronic Traumatic Encephalopathy, providing diagnostic support to forensic pathologists. Additionally, it seeks to aid in the differential diagnosis of similar conditions. Methods: A review of literature was conducted following the PRISMA criteria. Of 274 articles, 7 were selected. Results: According to these papers, most patients were male and exhibited neurological symptoms and neuropsychiatric impairments, and a proportion of them committed suicide or had aggressive behavior. Conclusions: Chronic Traumatic Encephalopathy remains largely underdiagnosed during life. The definitive diagnosis of Chronic Traumatic Encephalopathy is established post-mortem through the identification of pathognomonic tauopathy lesions. Early and accurate antemortem recognition, particularly in at-risk individuals, is highly valuable for its differentiation from other neurodegenerative conditions, thereby enabling appropriate clinical management and potential interventions. Full article

Background/Objectives: Sepsis-induced cardiomyopathy (SIC) is a serious clinical disorder with a high death rate. Qifu decoction (QFD) is a renowned traditional Chinese medicine with documented pharmacological actions, such as anti-inflammatory, anti-oxidant and anti-apoptosis activities, and it has good therapeutic effects on cardiovascular diseases. This study aimed to reveal the cardioprotective effects and underlying mechanisms of QFD against SIC. Methods: Electrocardiography, histopathological examination, and biochemical indicator determination were carried out to investigate the cardioprotective effects of QFD in the treatment of LPS-induced SIC mice. Metabolomics and network pharmacology strategies were employed to preliminarily analyze and predict the mechanisms of QFD against SIC. Molecular docking and Western blot were further applied to validate the core targets and potential pathways for the treatment of SIC in in vitro and in vivo models. Results: It was found that QFD considerably enhanced cardiac function; attenuated myocardial injury; and reduced the serum levels of LDH, CK-MB, IL-1β, and TNF-α by 28.7%, 32.3%, 38.6%, and 36.7%, respectively. Metabolomic analysis showed that QFD could regulate seven metabolic pathways, namely, glutathione metabolism; alanine, aspartate, and glutamate metabolism; arachidonic acid metabolism; glycerophospholipid metabolism; purine metabolism; sphingolipid metabolism; and fatty acid metabolism. Network pharmacology suggested that the anti-SIC effect of QFD may be mediated through the TNF, toll-like receptor, NOD-like receptor, NF-κB, and PPAR signaling pathways. Additionally, 26 core targets were obtained. Molecular docking revealed that active ingredients such as formononetin, kaempferol, quercetin, and (R)-norcoclaurine in QFD had a high affinity for binding to PPARα and TLR4. Further Western blot validation indicated that QFD could regulate the protein levels of NLRP3, TLR4, NF-κB, IL-6, TNF-α, COX2, sPLA2, PPARα, CPT1B, and CPT2. Conclusions: This study demonstrates that QFD can alleviate SIC by suppressing the TLR4/NF-κB/NLRP3 inflammatory pathway and modulating impaired FAO through the activation of the PPARα/CPT pathway, highlighting QFD as a promising candidate drug for SIC treatment. Full article

This narrative review examines the effects of caffeine on brain health in older adults, with particular attention to its potential for dependence—an often-overlooked issue in geriatric care. Caffeine acts on central adenosine, dopamine, and glutamate systems, producing both stimulating and rewarding effects that can foster tolerance and habitual use. Age-related pharmacokinetic and pharmacodynamic changes prolong caffeine’s half-life and increase physiological sensitivity in the elderly. While moderate consumption may enhance alertness, attention, and possibly offer neuroprotective effects—especially in Parkinson’s disease and Lewy body dementia—excessive or prolonged use may lead to anxiety, sleep disturbances, and cognitive or motor impairment. Chronic exposure induces neuroadaptive changes, such as adenosine receptor down-regulation, resulting in tolerance and withdrawal symptoms, including headache, irritability, and fatigue. These symptoms, often mistaken for typical aging complaints, may reflect a substance use disorder yet remain under-recognized due to caffeine’s cultural acceptance. The review explores caffeine’s mixed role in neurological disorders, being beneficial in some and potentially harmful in others, such as restless legs syndrome and frontotemporal dementia. Given the variability in individual responses and the underestimated risk of dependence, personalized caffeine intake guidelines are warranted. Future research should focus on the long-term cognitive effects and the clinical significance of caffeine use disorder in older populations. 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

The vertebrate retina is a complex neural tissue composed of a repeating array of distinct cell types that communicate through specialized synaptic connections. The neurochemistry underlying these connections reveals the synaptic chemistry, including the neurotransmitters involved and their corresponding receptors. The basic pattern of communication is that the pathway from photoreceptors to bipolar cells to ganglion cells typically uses glutamate as the signaling transmitter, with three ionotropic and one metabotropic receptor types. In contrast, much of the lateral feedback, performed by horizontal cells and amacrine cells, uses the inhibitory neurotransmitter GABA, while other amacrine cells use glycine or dopamine. This review examines all of these neurotransmitter systems for each retinal cell type, along with how these systems process the visual signals transmitted to the lateral geniculate nucleus and the visual cortex. 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

Neuropathic pain is a persistent and exhausting condition which results from damage to the nervous system and is often accompanied by emotional and cognitive impairments. In this study, we investigated dynamic changes in pain-related behaviors over 8 weeks using a spared nerve injury (SNI) model in male C57Bl/6 mice. We examined behavioral outcomes in conjunction with glial activation, neurogenesis, and glutamatergic signaling in the hippocampus to elucidate the mechanisms underlying cognitive and affective alterations associated with chronic pain. Our findings demonstrate that SNI-induced neuropathic pain progressively increases anxiety-like behavior and impairs both working and long-term memory. These behavioral deficits are accompanied by significant activation of microglia and astrocytes, a reduction in hippocampal neurogenesis, and a decrease in the expression of NMDA and AMPA glutamate receptor subunits and the scaffolding protein PSD-95. Taken together, our results suggest that hippocampal neuroinflammation and associated synaptic dysfunction contribute to the affective and cognitive disturbances observed in chronic pain, providing insight into potential molecular targets for therapeutic intervention. Full article

Ionotropic glutamate receptors—including N-methyl-d-aspartate (NMDA), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), and kainate receptors—play a pivotal role in excitatory signaling in the central nervous system (CNS), which is particularly important for learning and memory processes. Among them, AMPA and kainate receptors (known as ‘non-NMDA’ receptors) have gained increasing attention as therapeutic targets for various CNS disorders. Positive allosteric modulators (PAMs) of these receptors enhance their activity without directly activating them, offering a promising strategy to fine-tune glutamatergic signaling with potentially fewer side effects compared to orthosteric agonists. This review presents a comprehensive overview of recent advances in the development of AMPA and kainate receptor PAMs. We classify the most relevant modulators into main chemotype groups and discuss their binding modes, structure–activity relationships, and efficacy as determined through in vitro and in vivo studies. Additionally, we provide an overview of AMPA receptor PAMs that have entered into clinical trials over the past few decades. The increasing interest in kainate receptor PAMs is also mentioned, underlining their emerging role in future neuropharmacological strategies. Full article

Glutamate is one of the major naturally occurring non-essential amino acids. The aim of this review is to provide a comprehensive analysis of the role of glutamate as a key metabolite in the metabolism of plant and animal organisms. Its role in nutrition and neurotransmission has intrigued researchers for many years. In both plants and animals, glutamate primarily exists in a monoanionic form characterised by unique physical and chemical properties. In plants, it is involved in the glutamine synthetase/glutamate synthase (GS/GOGAT) cycle, while in animals, it plays a role in the glutamine/glutamate cycle, which is closely related to the urea cycle. Glutamate is also closely linked to the Krebs cycle in both groups of organisms through α-ketoglutarate. Glutamate is essential in both biosynthetic and catabolic pathways and participates in numerous physiological processes in plants and animals. Animals acquire glutamate from food, while plants acquire it from the soil; however, both also synthesise it de novo. Once present in the body, it is transported across cell membranes by specific transporters driven by ionic gradients (a mechanism known as secondary active transport). It is involved in cellular and systemic signalling pathways by interacting with ionotropic and metabotropic receptors. Additionally, glutamate is an important ‘building block’ of many proteins, including storage proteins. It also occurs in the form of monosodium glutamate (MSG), a flavour enhancer that is widely used but often criticised. Due to its important role in metabolism and signalling, the significance of glutamate in nutrition and its impact on human health are vital areas of research in food biochemistry. These investigations contribute to the development of nutritious food products and the design of effective pharmaceuticals. In this paper, we also address unresolved questions in glutamate research and consider its practical applications. Full article

Kernicterus spectrum disorder is the permanent and highly disabling neurologic sequel of neonatal exposure to hyperbilirubinemia, presenting, among other symptoms, variable and untreatable motor disabilities. To search for potential biomolecular explanations, we used a Gunn rat colony exhibiting spontaneous hyperbilirubinemia and a large variability of motor deficits on a beam-walking test. Histological and microscopic analyses confirmed worsening damage in the cerebellum (Cll; hypoplasia, increased death of neurons, and disrupted astroglial structures) and parietal motor cortex (hCtx; increased cell sufferance and astrogliosis). Clustering and network analyses of transcriptomic data reveal rearrangement of the physiological expression patterns and signaling pathways associated with bilirubin neurotoxicity. Bilirubin content among hyperbilirubinemic (jj) animals is overlapped, which suggests that the amount of bilirubin challenge does not fully explain the tissue, transcriptomic, proteomic, and neurobehavioral alterations. The expression of nine genes involved in key postnatal brain development processes is permanently altered in a phenotype-dependent manner. Among them, Grm1, a metabotropic glutamatergic receptor involved in glutamate neurotoxicity, is consistently downregulated in both brain regions both at the transcriptomic and proteomic levels. Our results support the role of Grm1 and glutamate as biomolecular markers of ongoing bilirubin neurotoxicity, suggesting the possibility to improve diagnosis by ¹H-MR spectroscopy. Full article

Delta-9-tetrahydrocannabinol (THC) is a psychoactive element of Cannabis sativa and affects the human cannabinoid system through its receptors, CB1R and CB2R. CB1R was found in several brain areas, including the hippocampal formation (HF), and it is responsible for most THC side effects. We investigated THC’s effects in the HF of female Wistar rats to assess changes in its neurotransmission. Female Wister rats (n = 20) were gonadectomized under anesthesia at 8 weeks old. Afterwards, they received estradiol benzoate (EB) and/or THC. Immunohistochemistry was performed to assess the expression of the cholinergic receptor alpha 7 subunit (CHRNA7), the vesicular acetylcholine transporter (VAChT), the vesicular glutamate transporter (VGLUT), the gamma-aminobutyric acid type A receptor (GABRA), the CB1 receptor, and estradiol receptor alpha (EBα). In the HF, the expression of CHRNA7 was increased by EB and by THC in the Oil groups but decreased by THC in the EB groups. The same is true for VGLUT expression in the DG and hilum and for GABRA expression in the hilum. The expression of VAChT and CB1 is reduced by EB, while the concomitant administration of THC increases it. GAD expression is reduced by EB administration in CA1, CA3, and DG. Our results may help with decision-making regarding the prescription of low doses of THC as a therapeutical approach. Full article