Search Results (315)

One major challenge in cellular neuroscience is to elucidate how the accurate alignment of presynaptic release sites with postsynaptic densely clustered ligand-gated ion channels at chemical synapses is achieved upon synapse assembly. The clustering of neurotransmitter receptors at postsynaptic sites is a key moment of synaptogenesis and determinant for effective synaptic transmission. The number of the ionotropic neurotransmitter receptors at these postsynaptic sites of both excitatory and inhibitory synapses is variable and is regulated by different mechanisms, thus allowing the modulation of synaptic strength, which is essential to tune neuronal network activity. Several well-regulated processes seem to be involved, including lateral diffusion within the plasma membrane and local anchoring as well as receptor endocytosis and recycling. The molecular mechanisms implicated are numerous and were reviewed recently in great detail. The role of pre-synaptically released neurotransmitters within the complex regulatory apparatus organizing the postsynaptic site underneath presynaptic terminals is not completely understood, even less for inhibitory synapses. In this mini review article, we focus on this aspect of synapse formation, summarizing and contrasting findings on the functional role of the neurotransmitters glycine and γ-aminobutyric acid (GABA) for initiation of postsynaptic receptor clustering and regulation of Cl⁻ channel receptor numbers at inhibitory synapses gathered over the last two decades. 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

Botulinum neurotoxins (BoNTs) are known to inhibit synaptic transmission by targeting SNARE proteins, but their selectivity toward central excitatory and inhibitory pathways is not yet fully understood. In this study, the interaction of serotypes A (BoNT/A) and B (BoNT/B) with the glutamatergic and GABAergic systems has been investigated using a pharmacological approach in an animal model of inflammatory pain, i.e., the formalin test in mice. BoNTs were administered intracerebroventricularly, three days before testing, followed 15 min before testing by systemic administration of sub-analgesic doses of MK801, an NMDA receptor antagonist, or muscimol, a GABA_A receptor agonist. BoNT/A reduced the second phase of the formalin test without affecting both the first phase and the interphase, suggesting a selective action on excitatory glutamatergic circuits while sparing GABAergic inhibition. Co-administration of MK801 with BoNT/A did not enhance analgesia, and muscimol did not further reduce interphase, confirming preserved GABAergic transmission. In contrast, BoNT/B abolished the interphase, consistent with impaired GABA release. Co-administration of MK801 or muscimol with BoNT/B restored the interphase, indicating compensatory rebalancing of excitatory-inhibitory networks. These results demonstrate that BoNT/A and BoNT/B exert distinct effects on central neurotransmission and support the hypothesis that BoNT/A preferentially targets excitatory synapses, while BoNT/B targets inhibitory synapses. This work contributes to a deeper understanding of anti-inflammatory mechanisms of BoNTs and their selective interaction with central pain pathways. Full article

Epilepsy remains a major therapeutic challenge, with approximately one-third of patients experiencing drug-resistant epilepsy (DRE) despite the availability of multiple antiseizure medications (ASMs). This review aims to evaluate emerging ASMs—cenobamate, fenfluramine, ganaxolone, ezogabine (retigabine), and perampanel—with a focus on their mechanisms of action, pharmacological profiles, and potential role in precision medicine. A comprehensive literature search was conducted using PubMed, Scopus, and Web of Science to identify preclinical and clinical studies evaluating the pharmacodynamics, pharmacokinetics, efficacy, and safety of the selected ASMs. Relevant trials, reviews, and mechanistic studies were reviewed to synthesize the current understanding of their application in DRE and specific epilepsy syndromes. Each ASM demonstrated unique mechanisms targeting hyperexcitability, including the modulation of γ-aminobutyric acid receptor A (GABA-A) receptors, sodium and potassium channels, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPA receptors), and serotonin systems. These mechanisms correspond with specific pathophysiological features in syndromes such as Dravet and Lennox–Gastaut. Evidence from clinical trials supports their use as adjunctive therapies with generally favorable tolerability, though adverse events and variable efficacy profiles were noted. The mechanistic diversity of these emerging ASMs supports their value in personalized epilepsy management, particularly in treatment-resistant cases. While the promise of precision medicine is evident, further studies are required to address challenges related to long-term safety, cost, and equitable access. Full article

Epilepsy remains a widespread neurological disorder, with approximately 30% of patients showing resistance to current antiepileptic therapies. To address this unmet need, a series of 2-(isoindolin-2-yl) esters derived from natural amino acids were designed and evaluated for their potential interaction with the GABA_A receptor. Sixteen derivatives were subjected to in silico assessments, including physicochemical and ADMET profiling, virtual screening–ensemble docking, and enhanced sampling molecular dynamics simulations (metadynamics calculations). Among these, compounds derived from the aromatic amino acids, phenylalanine, tyrosine, tryptophan, and histidine, exhibited superior predicted affinity, attributed to π–π stacking interactions at the benzodiazepine binding site of the GABA_A receptor. Based on computational performance, the tyrosine and tryptophan derivatives were synthesized and further assessed in vivo using the pentylenetetrazole-induced seizure model in zebrafish (Danio rerio). The tryptophan derivative produced comparable behavioral seizure reduction to the reference drug diazepam at the tested concentrations. The results implies that aromatic amino acid-derived isoindoline esters are promising anticonvulsant candidates and support the hypothesis that π–π interactions may play a critical role in modulating GABA_A receptor binding affinity. Full article

The GABA_A receptors, through a short-term interaction with a mediator, induce hyperpolarization of the membrane potential (V_m) via the passive influx of chloride ions (Cl⁻) into neurons. The massive (or intense) activation of the GABA_ARs by the agonist could potentially lead to depolarization/excitation of the V_m. Although the ionic mechanisms of GABA_A-mediated depolarization remain incompletely understood, a combination of the outward chloride current and the inward bicarbonate current and the resulting pH shift are the main reasons for this event. The GABA_A responses are determined by the ionic gradients—neuronal pH/bicarbonate homeostasis is maintained by carbonic anhydrase and electroneutral/electrogenic bicarbonate transporters and the chloride level is maintained by secondary active cation–chloride cotransporters. Massive activation can also induce the rundown effect of the receptor function. This rundown effect partly involves phosphorylation, Ca²⁺ and the processes of receptor desensitization. In addition, by various methods (including fluorescence and optical genetic methods), it has been shown that massive activation of GABA_ARs during pathophysiological activity is also associated with an increase in [Cl⁻]_i and a decline in the pH and ATP levels in neurons. Although the relationship between the neuronal changes induced by massive activation of GABAergic signaling and the risk of developing neurodegenerative disease has been extensively studied, the molecular determinants of this process remain somewhat mysterious. The aim of this review is to summarize the data on the relationship between the massive activation of inhibitory signaling and the ionic changes in neurons. The potential role of receptor dysfunction during massive activation and the resulting ionic and metabolic disruption in neurons during the manifestation of network/seizure activity will be considered. Full article

Medulloblastoma (MB) is the most common malignant brain tumor in children and typically arises in the cerebellum, likely due to disruptions in neuronal precursor development. The primary inhibitory neurotransmitter in the central nervous system (CNS), γ-aminobutyric acid (GABA), exerts its effects through GABA_A, GABA_B, and GABA_C receptors. GABA receptor activity regulates the development and function of cerebellar neurons, including glutamatergic cerebellar granule cells (CGCs). Beyond the nervous system, GABA is also a common metabolite in non-neuronal cell types. An increasing body of evidence indicates that GABA can influence cell proliferation, differentiation, and migration in several types of adult solid tumors, including brain cancers. GABA and GABA_A receptor agonists can impair the viability and survival of MB cells, primarily acting on GABA_A receptors containing the α5 subunit. A marked expression of the gene encoding the α5 subunit is found across all MB tumor molecular subgroups, particularly Group 3 MB, which has a poor prognosis. Importantly, high levels of the γ-aminobutyric acid type A receptor subunit α5 (GABRA5) gene are associated with shorter patient overall survival in Group 3 and Group 4 MB. In contrast, high γ-aminobutyric acid type A receptor subunit β1 (GABRB1) gene expression is related to longer survival in all MB subgroups. The GABAergic system may, therefore, regulate MB cell function and tumor progression and influence patient prognosis, and is worthy of further investigation as a biomarker and therapeutic target in MB. Full article

Postpartum depression (PPD) remains a significant health concern worldwide. Both non-pharmacological and pharmacological treatments are available for patients with PPD; however, the standard approach involving selective serotonin reuptake inhibitors (SSRIs) and other antidepressants fails to provide a rapid response. This narrative review presents basic clinical and epidemiological data on PPD, summarizes currently used pharmacotherapies of PPD, highlights their limitations, and discusses new therapies based on a revised understanding of the disease’s pathogenesis. Numerous studies indicate that dysregulation of GABAergic neurotransmission, which may result from fluctuating levels of neuroactive steroids during pregnancy and the postpartum period, plays an important role in the complex pathology of PPD. Considering this, neuroactive steroids, which act as positive allosteric modulators of central GABA_A receptors (GABA_ARs), may offer new promising avenues for treating PPD. The first rapid-acting neurosteroid approved by the FDA to treat PPD in women is brexanolone, although its use is constrained by pharmacokinetic properties. The first oral neuroactive steroid-based antidepressant approved by the FDA for PPD is zuranolone. This review discusses the molecular mechanism of zuranolone action and the results of preclinical and clinical studies regarding the effectiveness and safety of the drug in treating PPD. Full article

The current study evaluated the anticonvulsant properties of ethanolic extracts from Morus alba, Angelica archangelica, Passiflora incarnata, and Valeriana officinalis using integrated phytochemical, in vivo, biochemical, and computational approaches. Phytochemical analysis by UHPLC-HRMS/MS revealed the presence of various bioactive compounds, notably flavonoids such as isorhamnetin, quercetin, and kaempferol. In an electroshock-induced seizure model, Morus alba extract (MAE, 100 mg/kg) demonstrated significant anticonvulsant effects, reducing both seizure duration and incidence, likely mediated by flavonoid interactions with GABA-A and 5-HT3A receptors, as suggested by target prediction and molecular docking analyses. The extracts of Angelica archangelica (AAE, 100 mg/kg) and Passiflora incarnata (PIE, 50 mg/kg) exhibited moderate, non-significant anticonvulsant activities. At the same time, Valeriana officinalis (VOE, 50 mg/kg) displayed considerable antioxidant and anti-inflammatory properties but limited seizure protection. All extracts significantly reduced brain inflammation markers (TNF-α) and enhanced antioxidant defenses, as indicated by total thiols. Molecular docking further supported the interaction of key phytochemicals, including naringenin and chlorogenic acid, with human and mouse 5-HT3A receptors. Overall, Morus alba extract exhibited promising therapeutic potential for epilepsy management, warranting further investigation into chronic seizure models and optimized dosing strategies. Full article

Neurosteroids pregnenolone, progesterone, allopregnanolone, and dehydroepiandrosterone have been actively studied in the last years as candidates for the treatment of neurodegenerative diseases and postinjury rehabilitation. The neuroprotective mechanisms of these neurosteroids have been shown in clinical studies of depression, epilepsy, status epilepticus, traumatic brain injury, fragile X syndrome, and chemical neurotoxicity. However, only the allopregnanolone analogs brexanolone and zuranolone have been recently approved by the FDA for the treatment of depression. The aim of this review was to evaluate whether the endogenous neurosteroids can be used in clinical practice as neuroprotectors. Neurosteroids are multitarget compounds with strong anti-inflammatory, immunomodulatory, and cytoprotective action; they stimulate the synthesis and release of BDNF and increase remyelination and regeneration. In addition to nuclear and membrane steroid hormone receptors, such as PR, mPR, PGRMC1,2, ER, AR, CAR, and PXR, they can bind to GABAA receptors, NMDA receptors, Sigma-1 and -2 receptors (σ1-R/σ2-R). Among these, mPRs, PGRMC1,2, sigma receptors, and mitochondrial proteins attract comprehensive attention because of strong binding with the P4 and DHEA, but subsequent signaling is poorly studied. Other plasma membrane and mitochondrial proteins are involved in the rapid nongenomic neuroprotective action of neurosteroids. P-glycoprotein, BCL-2 proteins, and the components of the mitochondrial permeability transition pore (mPTP) play a significant role in the defense against the injuries of the brain and the peripheral nervous system. The role of these proteins in the molecular mechanisms of action in neuroprotection and neuroinflammation has not yet been clearly established. The aspects of their participation in these pathological processes are discussed. New formulations, such as lipophilic emulsions, nanogels, and microneedle array patches, are attractive strategies to overcome the low bioavailability of these neurosteroids for the amelioration and treatment of various nervous disorders. Full article

Although some GABA_A receptor subtypes are involved in both the passive permeability of anions and the ATP-dependent recovery of neuronal anion concentrations, the molecular mechanisms that ensure the coordination of passive and active transport processes remain unclear. Here we used fluorescence measurements to investigate the role of genistein (tyrosine kinase inhibitor) and vanadate (tyrosine phosphatase and ATPase inhibitor) in modulating GABA_AR-mediated [Cl⁻]_i/[HCO₃⁻]_i changes and ATPase activity in rat cortical neurons and HEK 293FT cells expressing the heteropentameric α2β3γ2 GABA_AR isoform. We found that genistein plays an important role in the inhibition of passive GABA_AR-mediated Cl⁻ influx and Cl⁻ATPase activity, whereas vanadate plays an important role in the inhibition of Cl⁻, HCO₃⁻ATPase activity and ATP-dependent recovery of [HCO₃⁻]_i via changes in the formation of the phosphorylated intermediate. The effect of blockers was significantly restored in the presence of phenol. In behavioral experiments, the administration of phenol has been established to induce tremors and head twitching in rats, with the involvement of GABA_AR/ATPase in these behavioral responses. Genistein can reduce the adverse effects of phenol, thereby confirming the interaction of these chemicals when binding to binding receptor sites. While our data demonstrate the opposing roles of genistein and vanadate in modulating GABA_AR/ATPase function in a bicarbonate-dependent manner. Such multidirectional systems are considered to be bistable elements involved in the regulatory mechanisms of synaptic plasticity. Full article

This study investigated the effects of lemon verbena extract (LVE) on sleep regulation using both a pentobarbital-induced sleep model and an EEG-based sleep assessment model in mice. To elucidate its potential mechanisms, mice were randomly assigned to five groups: control, positive control (diazepam, 2 mg/kg b.w.), and three LVE-treated groups receiving 40, 80, or 160 mg/kg b.w. via oral administration. In the pentobarbital-induced sleep model, mice underwent a two-week oral administration of LVE, followed by intraperitoneal pentobarbital injections. The results demonstrated that LVE significantly shortened sleep latency and prolonged sleep duration compared to the control group. Notably, adenosine A1 receptor expression, both at the mRNA and protein levels, was markedly upregulated in the brains of LVE-treated mice. Furthermore, LVE’s administration led to a significant increase in the mRNA expression of gamma-aminobutyric acid type A (GABA_A) receptor subunits (α2 and β2) in brain tissue. In the electroencephalography (EEG)/electromyogram (EMG)-based sleep model, mice underwent surgical implantation of EEG and EMG electrodes, followed by one week of LVE administration. Quantitative EEG analysis revealed that LVE treatment reduced wakefulness while significantly enhancing REM and NREM sleep’s duration, indicating its potential sleep-promoting effects. These findings suggest that LVE may serve as a promising natural sleep aid, improving both the quality and duration of sleep through the modulation of adenosine and GABAergic signaling pathways. Full article

Anesthesia is a cornerstone of modern medicine, enabling surgery, pain management, and critical care. Despite its widespread use, the precise molecular mechanisms of anesthetic action remain incompletely understood. Recent advancements in structural biology, including cryo-electron microscopy (Cryo-EM), X-ray crystallography, and computational modeling, have provided high-resolution insights into anesthetic–target interactions. This review examines key molecular targets, including GABA_A receptors, NMDA receptors, two-pore-domain potassium (K2P) channels (e.g., TREK-1), and voltage-gated sodium (Nav) channels. General anesthetics modulate GABA_A and NMDA receptors, affecting inhibitory and excitatory neurotransmission, while local anesthetics primarily block Nav channels, preventing action potential propagation. Structural studies have elucidated anesthetic binding sites and gating mechanisms, providing a foundation for drug optimization. Advances in computational drug design and AI-assisted modeling have accelerated the development of safer, more selective anesthetics, paving the way for precision anesthesia. Future research aims to develop receptor-subtype-specific anesthetics, Nav1.7-selective local anesthetics, and investigate the neural mechanisms of anesthesia-induced unconsciousness and postoperative cognitive dysfunction (POCD). By integrating structural biology, AI-driven drug discovery, and neuroscience, anesthesia research is evolving toward safer, more effective, and personalized strategies, enhancing clinical outcomes and patient safety. Full article

Background: The GABA_A receptor (GABAAR) potentiator, KRM-II-81, is being developed as a novel antiseizure medication with reduced potential for sedation, tolerance development, and abuse liability. Although KRM-II-81 has been shown to provide antiseizure protection against a broad array of seizure induction paradigms, seizures induced by viral vectors have not been previously studied. GABAARs with specific α subunit compositions have been studied in relation to the reduced side-effect liability of KRM-II-81; however, the role of β subunit composition has yet to be determined. Methods: In the present study, KRM-II-81 was studied against handling-induced seizures in Theiler’s murine encephalomyelitis virus (TMEV)-infected mice. Results: An intracerebral infusion of TMEV on day 0 increased the cumulative seizure burden in mice when assessed for handling-induced seizures on days 3–7. KRM-II-81 (15 mg/kg, p.o., bid) nearly completely suppressed seizures in TMEV-infected mice over the course of daily treatments. The number of the most severe seizures (stage 5, tonic/clonic seizures) in the mice was suppressed to zero by KRM-II-81. Although the selectivity of KRM-II-81 for GABAAR α2/3 receptor subtypes might imbue KRM-II-81 with a reduced side-effect liability, other mechanisms are possible, and the potentiation of β1-containing GABAARs has been implicated in inducing sedation. The role of β subunit composition has yet to be determined for KRM-II-81. In electrophysiological studies with cells transfected with α_xβ₁γ₂ or α_xβ₃γ₂, KRM-II-81 preferentially potentiated GABA responses in cells containing β3 subunits in α2/3-containing GABAARs. Conclusions: The present findings confirm the robust antiseizure activity of KRM-II-81, now extended to a virus-induction model, and suggest a possible role of reduced β1-potentiation in the low side-effect profile of KRM-II-81. Full article

Zuranolone (SAGE-217), the first FDA-approved oral neurosteroid (NAS), a positive allosteric modulator (PAM) of γ-aminobutyric acid type A (GABA_A) receptor for postpartum depression approved in 2023, has limitations such as short half-life, low bioavailability, and central inhibitory side effects. To address these, we designed novel C-21 modified derivatives of Zuranolone, identifying the triazolone scaffold as key for enhancing GABA_A activity. Here, we synthesized Zuranolone analogs with diverse triazolone substituents, finding that pyridine-derived modifications improved the activity correlated with LogP. The optimal derivative, S9 (2-(trifluoroethoxy)pyridine-triazolone, LogP 4.61), showed 2.5-fold greater potency (EC₅₀) and efficacy (Emax) than Zuranolone (LogP 4.78) at synaptic/extrasynaptic GABA_A receptors, attributed to stronger binding via molecular docking. In rats, S9 exhibited 5-fold longer plasma T_1/2, 6-fold higher AUC, 3-fold greater brain exposure, and 30% improved bioavailability. It also outperformed Zuranolone in pentylenetetrazole (PTZ)-induced seizure suppression and threshold dose for loss of righting reflex (LORR) in rats. The C21-pyridine-triazolone pharmacophore in S9 enhances receptor activity potency without increasing lipophilicity, optimizing pharmacokinetics and safety, which makes it a promising therapeutic candidate for depression and epilepsy. Full article