Search Results (50)

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

Background/Objectives: GL-II-73 is a positive allosteric modulator that is selective for α5GABA_A receptors and has physicochemical properties that favor nanocarrier formulations when parenteral delivery to the central nervous system is desired. Our aim was to develop an optimized nanoemulsion containing GL-II-73 and subsequently test whether this would improve permeation across the blood–brain barrier (BBB) and availability in the brain. Methods: The nanoemulsions were formulated and subjected to detailed physiochemical characterization. The optimized formulation was tested in comparison to a solution of GL-II-73 in the appropriate solvent in an in vitro model of the blood–brain barrier based on human induced pluripotent stem cell-derived microvascular endothelial cells, astrocytes, and pericytes. Plasma and brain exposure to GL-II-73 and its metabolite MP-III-022 was investigated in an in vivo neuropharmacokinetic study in rats exposed to the selected nanoemulsion and the conventional solution formulation. Results: The selected biocompatible nanoemulsion exhibited satisfactory physicochemical properties for parenteral administration, with a Z-ave of 122.0 ± 1.5, PDI of 0.123 ± 0.009 and zeta potential of −40.7 ± 1.5, pH of 5.16 ± 0.04, and adequate stability after one year of storage, and allowed the localization of GL-II-73 in the stabilization layer. The permeability of GL-II-73 through the BBB was twice as high with the selected nanoemulsion as with the solution. The availability of GL-II-73 and MP-III-022 (also a positive allosteric modulator selective for α5GABA_A receptors) in the brain was 24% and 61% higher, respectively, after intraperitoneal administration of the nanoemulsion compared to the solution; the former increase was statistically significant. Conclusions: The increased permeability in vitro proved to be a good predictor for the improved availability of GL-II-73 in brain tissue in vivo from the formulation obtained by encapsulation in a nanoemulsion. The putative additive effect of the parent molecule and its metabolite MP-III-022 could lead to enhanced and/or prolonged modulation of α5GABA_A receptors in the brain. Full article

Background and aims: Aframomum melegueta (A. melegueta) from the ginger family is appreciated for its pungent seeds widely used in African ethno-medicine. Among the several biological activities associated with the seed’s preparations, some preclinical studies suggest a set of neuroactive properties that have not been tested in humans to date. We performed a clinical trial to investigate the effects of A. melegueta seed extracts on anxiety, stress, mood, and sleep in healthy subjects with moderate anxiety levels. In vitro pharmacological assays targeting the endocannabinoid, serotoninergic, and GABAergic systems were conducted to elucidate the underlying mechanism of action. Methods: A. melegueta standardized to 10% total vanilloids (primarily 6-gingerol, 6-shogaol, and 6-paradol) was obtained after hydroalcoholic extraction and the spray-drying microencapsulation process. Subjects consumed 50, 100, or 150 mg of the extract daily for three days. A set of validated psychometric test questionnaires was collected before and 48 h after the first intake. A. melegueta extract interaction with canonical endocannabinoid receptors (hCB1R and hCB2R), the serotonin receptor (5HT1AR) and gamma-aminobutyric acid receptor (GABAA1R) was evaluated by the radioligand binding assay. Additionally, receptor functional assays and enzyme inhibition assays were conducted to test the extract’s functional activity on the non-canonical endocannabinoid receptor (TRPV1) and the cannabinoid fatty-acid amide hydrolase enzyme (FAAH), respectively. Results: In vitro pharmacological tests showed that the A. melegueta extract activated TRPV1, modulated both hCB2R and 5HT1AR and inhibited FAAH, which is the enzyme primarily responsible for hydrolyzing endogenous anandamide. After a 48 h intake period, the extract significantly reduced anxiety and tension related to stress, improved overall mood, and enhanced sleep quality in the participants at doses ranging from 50 to 150 mg, with no reported side effects. Conclusions: This study supports the potential of the A. melegueta extract for anxiety reduction, mood improvement, stress mitigation, and sleep enhancement. The in vitro tests suggest that the extract’s primary mechanism of action may involve the inhibition of FAAH, which is a key target in anxiety management. Full article

Cenobamate is a new and highly effective antiseizure compound used for the treatment of adults with focal onset seizures and particularly for epilepsy resistant to other antiepileptic drugs. It acts on multiple targets, as it is a positive allosteric activator of γ-aminobutyric acid type A (GABA_A) receptors and an inhibitor of neuronal sodium channels, particularly of the late or persistent Na⁺ current. We recently evidenced the inhibitory effects of cenobamate on the peak and late current component of the human cardiac isoform hNav1.5. The determined apparent IC₅₀ values of 87.6 µM (peak) and 46.5 µM (late current) are within a clinically relevant range of concentrations (the maximal plasma therapeutic effective concentration for a daily dose of 400 mg in humans is 170 µM). In this study, we built a 3D model of the canonical hNav1.5 channel (UniProt Q14524-1) in open conformation using AlphaFold2, embedded it in a DPPC lipid bilayer, corrected the residue protonation state (pH 7.2) with H++, and added 2 Na⁺ ions in the selectivity filter. By molecular docking, we found the cenobamate binding site in the central cavity. We identified 10-point mutant variants in the binding site region and explored them via docking and MD. Mutants N1462K/Y (rs1064795922, rs199473614) and M1765R (rs752476527) (by docking) and N932S (rs2061582195) (by MD) featured higher predicted affinity than wild-type. Full article

Infantile spasms are common in Down Syndrome (DS), but the mechanisms by which DS predisposes to this devastating epilepsy syndrome are unclear. In general, neuronal excitability and therefore seizure predisposition results from an imbalance of excitation over inhibition in neurons and neural networks of the brain. Animal models provide clues to mechanisms and thereby provide potential therapeutic approaches. Ts65Dn mice have been the most widely used animal model of DS. In this model, there is evidence for both abnormal cerebral excitation and inhibition: infantile spasms-like clinical and electrographic activity can be elicited by the administration of gamma-aminobutyric acid (GABA)-B receptor agonist, gamma-butyrolactone (GBL), and depolarizing GABA-A responses persist beyond the age of their usual switch to hyperpolarized responses. But despite its widespread use, the Ts65Dn model may be suboptimal because of the absence of numerous genes that are triplicated in human DS and the presence of numerous genes that are not triplicated in human DS. Recently, a transchromosomic mouse artificial chromosome 21 (TcMAC21) mouse model has been developed, which carries a copy of human chromosome 21 and therefore has a genetic composition more similar to human DS. As in Ts65Dn mice, exposure of TcMAC21 mice to GBL results in epileptic spasms, and aberrant excitation has also been demonstrated. This review summarizes excitatory and inhibitory dysfunction in models of DS that may play a role in the generation of seizures and infantile spasms, providing a perspective on past studies and a prelude for future ones. Further elucidation will hopefully lead to rational therapeutic options for DS children with infantile spasms. Full article

Cenobamate is a novel third-generation antiepileptic drug used for the treatment of focal onset seizures and particularly for multi-drug-resistant epilepsy; it acts on multiple targets: GABA_A receptors (EC₅₀ 42–194 µM) and persistent neuronal Na⁺ currents (IC₅₀ 59 µM). Side effects include QT_c interval shortening with >20 ms, but not <300 ms. Our in vitro cardiac safety pharmacology study was performed via whole-cell patch-clamp on HEK293T cells with persistent/inducible expression of human cardiac ion channel isoforms hNav1.5 (I_Na), hCav1.2 (α1c + β2 + α2δ1) (I_CaL), hKv7.1 + minK (I_Ks), and hKv11.1 (hERG) (I_Kr). We found IC50 of 87.6 µM (peak I_Na), 46.5 µM (late I_Na), and 509.75 µM (I_CaL). In experiments on Ncyte^® ventricular cardiomyocytes, APD90 was reduced with 28.6 ± 13.5% (mean ± SD) by cenobamate 200 µM. Cenobamate’s marked inhibition of I_Na raises the theoretical possibility of cardiac arrhythmia induction at therapeutic concentrations in the context of preexisting myocardial pathology, in the presence of action potential conduction and repolarization heterogeneity. This hypothetical mechanism is consistent with the known effects of class Ib antiarrhythmics. In simulations with a linear strand of 50 cardiomyocytes with variable inter-myocyte conductance based on a modified O’Hara–Rudy model, we found a negligible cenobamate-induced conduction delay in normal tissue, but a marked delay and also a block when gap junction conduction was already depressed. Full article

Background: Sleep, a process physiologically vital for mental health, faces disruptions in various sleep disorders linked to metabolic and neurodegenerative risks. Zizyphus seed (Zizy) has long been recognized for its diverse pharmacological attributes, including analgesic, sedative, insomnia, and anxiety alleviation. Objectives: In this study, the sleep-prolonging effects of Zizy extract (100, 200 mg/kg), along with their characterizing compounds jujuboside A (JuA) (5, 10 mg/kg), were evaluated in a mouse model under a pentobarbital-induced sleep. Additionally, the efficacy of Zizy extract was examined on caffeine-induced insomnia in mice. Methods: To confirm the efficacy of Zizy extract on the structure and quality of sleep, an electroencephalogram (EEG) analysis of rats was performed using the MATLAB algorithm. Additionally, Western blot analysis and measurement of intracellular chloride influx were performed to confirm whether these effects acted through the gamma-aminobutyric acid (GABA)ergic system. Administration of Zizy extract showed no effect on the locomotor performance of mice, but the extract and their characteristic compounds significantly prolonged sleep duration in comparison to the pentobarbital alone group in the pentobarbital-induced sleep mouse model. Furthermore, this extract alleviated caffeine-induced insomnia in mice. Results: The administration of Zizy extract extended non-rapid eye movement sleep (NREMS) duration without inducing significant changes in the brain wave frequency. Zizy extract regulated the expression of GABA_A receptor subunits and GAD65/67 in specific brain regions (frontal cortex, hippocampus, and hypothalamus). JuA increased intracellular chloride influx in human SH-SY5Y cells, and it was reduced by GABA_A receptor antagonists. These results suggest that the sleep-maintaining effects of Zizy extract may entail GABAergic regulation. In summary, Zizy extract demonstrated sleep-prolonging properties, improved insomnia, and regulated sleep architecture through GABAergic system modulation. Conclusions: These findings suggest that Zizy extract has potential as a therapeutic agent for stress-related neuropsychiatric conditions such as insomnia. Full article

Background: Grape seed extract (GSE) from Vitis vinifera L. is rich in polyphenols and oligomeric proanthocyanidin complexes (OPCs), and it has shown potential benefits in managing low mood and cognitive function. In this study, we investigated the potential bioactivities of Enovita^®, a standardized GSE extract (GSEe herein) rich in OPCs, in key mechanistic pathways related to low mood conditions and cognitive function. Methods: In vitro assays were conducted to assess GSEe’s inhibitory effects on γ-aminobutyric acid transaminase (GABA-T) and monoamine oxidase A (MAO-A), its binding affinity to the GABA site of GABA-A receptors, and its effects on acetylcholinesterase (AChE). Its neuroprotective effects on human SH-SY5Y neuroblastoma cells under oxidative stress (induced by H₂O₂) were assessed using MTT and LDH release assays. Its antioxidant activities were evaluated using DPPH, ABTS, FRAP, ORAC, HORAC, total phenolic content, and TAS assays. Its cytotoxicity was also evaluated. Results: GSEe showed significant GABA-T inhibitory activity. It also exhibited MAO-A and AChE inhibition, along with moderate binding affinity to the GABA-A receptor. In neuroprotective assays, GSEe provided significant protection to SH-SY5Y cells against oxidative stress. GSEe demonstrated robust antioxidant activity in all assays, including scavenging of DPPH and ABTS radicals, high ferric-reducing power, high polyphenolic contents, and a substantial total antioxidant capacity. Conclusions: GSEe exhibits promising bioactivities, highlighting its potential as a supplement for modulating mood and enhancing cognitive function. Overall, the promising results from these in vitro studies provide a strong foundation for the continued exploration and development of GSEe as a viable natural supplement for enhancing mental health and cognitive function. Full article

Type-A γ-aminobutyric acid (GABA_A) receptors are channel proteins crucial to mediating neuronal balance in the central nervous system (CNS). The structure of GABA_A receptors allows for multiple binding sites and is key to drug development. Yet the formation mechanism of the receptor’s distinctive pentameric structure is still unknown. This study aims to investigate the role of three predominant subunits of the human GABA_A receptor in the formation of protein pentamers. Through purifying and refolding the protein fragments of the GABA_A receptor α1, β2, and γ2 subunits, the particle structures were visualised with negative staining electron microscopy (EM). To aid the analysis, AlphaFold2 was used to compare the structures. Results show that α1 and β2 subunit fragments successfully formed homo-oligomers, particularly homopentameric structures, while the predominant heteropentameric GABA_A receptor was also replicated through the combination of the three subunits. However, homopentameric structures were not observed with the γ2 subunit proteins. A comparison of the AlphaFold2 predictions and the previously obtained cryo-EM structures presents new insights into the subunits’ modular structure and polymerization status. By performing experimental and computational studies, a deeper understanding of the complex structure of GABA_A receptors is provided. Hopefully, this study can pave the way to developing novel therapeutics for neuropsychiatric diseases. Full article

In non-small cell lung cancer (NSCLC) treatment, radiotherapy responses are not durable and toxicity limits therapy. We find that AM-101, a synthetic benzodiazepine activator of GABA(A) receptor, impairs the viability and clonogenicity of both primary and brain-metastatic NSCLC cells. Employing a human-relevant ex vivo ‘chip’, AM-101 is as efficacious as docetaxel, a chemotherapeutic used with radiotherapy for advanced-stage NSCLC. In vivo, AM-101 potentiates radiation, including conferring a significant survival benefit to mice bearing NSCLC intracranial tumors generated using a patient-derived metastatic line. GABA(A) receptor activation stimulates a selective-autophagic response via the multimerization of GABA(A) receptor-associated protein, GABARAP, the stabilization of mitochondrial receptor Nix, and the utilization of ubiquitin-binding protein p62. A high-affinity peptide disrupting Nix binding to GABARAP inhibits AM-101 cytotoxicity. This supports a model of GABA(A) receptor activation driving a GABARAP–Nix multimerization axis that triggers autophagy. In patients receiving radiotherapy, GABA(A) receptor activation may improve tumor control while allowing radiation dose de-intensification to reduce toxicity. Full article

Among the most prevalent neurological disorders, epilepsy affects about 1% of the population worldwide. We previously found, using human epileptic tissues, that GABAergic neurotransmission impairment is a key mechanism that drives the pathological phenomena that ultimately lead to generation and recurrence of seizures. Using both a “microtransplantation technique” and synaptosomes preparations from drug-resistant temporal lobe epilepsies (TLEs), we used the technique of two-electrode voltage clamp to record GABA-evoked currents, focusing selectively on the synaptic “fast inhibition” mediated by low-affinity GABA_A receptors. Here, we report that the use-dependent GABA current desensitization (i.e., GABA rundown, which is evoked by applying to the cells consecutive pulses of GABA, at high concentration), which is a distinguishing mark of TLE, is mainly dependent on a dysfunction that affects synaptic GABA_A receptors. In addition, using the same approaches, we recorded a depolarized GABA reversal potential in synaptosomes samples from the human epileptic subicula of TLE patients. These results, which confirm previous experiments using total membranes, suggest an altered chloride homeostasis in the synaptic area. Finally, the lack of a Zn²⁺ block of GABA-evoked currents using the synaptosomes supports the enrichment of “synaptic fast inhibitory” GABA_A receptors in this preparation. Altogether, our findings suggest a pathophysiological role of low-affinity GABA_A receptors at the synapse, especially during the fast and repetitive GABA release underlying recurrent seizures. Full article

Major depression is related to dysfunction of the GABAergic pathway. Interestingly, the antidepressant fluoxetine modifies GABAergic neurotransmission in human and animal models of depression. However, the effects of norfluoxetine (the main metabolite of fluoxetine) on GABAergic neurotransmission have not yet been studied. Therefore, we explored whether fluoxetine and/or norfluoxetine may regulate GABAergic transmission and whether these substances interact with GABA_A receptors in hippocampal CA1 stratum radiatum interneurons. For these purposes, we recorded the firing profile, GABAergic spontaneous inhibitory postsynaptic currents (sIPSCs), and currents induced by GABA puffs in stratum radiatum interneurons using both whole-cell current- and voltage-clamp techniques. Interneurons were selected according with their high firing profile. We found that both fluoxetine and norfluoxetine (at 20 µM) significantly decreased the frequency of sIPSCs without modifying their amplitude and decreased the amplitude of GABA-induced currents. These results indicate that fluoxetine and norfluoxetine decrease GABA release from neurons contacting stratum radiatum interneurons and negatively modulate GABA_A receptors in these interneurons, resulting in their disinhibition, which in turn may contribute to increasing the inhibition of hippocampal CA1 pyramidal neurons. Full article

Objectives In Vitro: To study the effects of GR3027 (golexanolone) on neurosteroid-induced GABA-mediated current responses under physiological GABAergic conditions with recombinant human α5β3γ2L and α1β2γ2L GABA_A receptors expressed in human embryonic kidney cells, using the response patch clamp technique combined with the Dynaflow™ application system. With α5β3γ2L receptors, 0.01–3 μM GR3027, in a concentration-dependent manner, reduced the current response induced by 200 nM THDOC + 0.3 µM GABA, as well as the THDOC-induced direct gated effect. GR3027 (1 μM) alone had no effect on the GABA-mediated current response or current in the absence of GABA. With α1β2γ2L receptors, GR3027 alone had no effect on the GABA-mediated current response or did not affect the receptor by itself. Meanwhile, 1–3 µM GR3027 reduced the current response induced by 200 nM THDOC + 30 µM GABA and 3 µM GR3027 that induced by 200 nM THDOC when GABA was not present. Objectives In Vivo: GR3027 reduces allopregnanolone (AP)-induced decreased learning and anesthesia in male Wistar rats. Rats treated i.v. with AP (2.2 mg/kg) or vehicle were given GR3027 in ratios of 1:0.5 to 1:5 dissolved in 10% 2-hydroxypropyl-beta-cyclodextrin. A dose ratio of AP:GR3027 of at least 1:2.5 antagonized the AP-induced decreased learning in the Morris Water Mase (MWM) and 1:7.5 antagonized the loss of righting reflex (LoR). GR3027 treatment did not change other functions in the rat compared to the vehicle group. Conclusions: GR3027 functions in vitro as an inhibitor of GABA_A receptors holding α5β3γ2L and α1β2γ2L, in vivo, in the rat, as a dose-dependent inhibitor toward AP’s negative effects on LoR and learning in the MWM. Full article

Of the 35 million people in the world suffering from Alzheimer’s Disease (AD), up to half experience comorbid psychosis. Antipsychotics, used to treat psychosis, are contraindicated in elderly patients because they increase the risk of premature death. Reports indicate that the hippocampus is hyperactive in patients with psychosis and those with AD. Preclinical studies have demonstrated that the ventral hippocampus (vHipp) can regulate dopamine system function, which is thought to underlie symptoms of psychosis. A viral-mediated approach was used to express mutated human genes known to contribute to AD pathology: the Swedish (K670N, M671L), Florida (I716V), and London (V717I) mutations of amyloid precursor protein and two mutations (M146L and L286V) of presenilin 1 specifically in the vHipp, to investigate the selective contribution of AD-like pathology in this region. We observed a significant increase in dopamine neuron population activity and behavioral deficits in this AD-AAV model that mimics observations in rodent models with psychosis-like symptomatologies. Further, systemic administration of MP-III-022 (α5-GABAA receptor selective positive allosteric modulator) was able to reverse aberrant dopamine system function in AD-AAV rats. This study provides evidence for the development of drugs that target α5-GABAA receptors for patients with AD and comorbid psychosis. Full article

Gamma-aminobutyric acid (GABA) is an essential neurotransmitter and an important regulator of neuroinflammation and disease. Microglia are important immune cells in the brain that express GABA receptors (GABAR) and respond to both GABA and GABAR agonists, yet the effect of GABA on microglial inflammatory responses is unclear. We hypothesized that GABA and GABAR agonists might modify the activation of a human microglial cell line (HMC3). We further hypothesized that Amanita muscaria extract (AME-1), which contained GABAR agonists (GABA and muscimol), would similarly stimulate HMC3. Ligand-gated GABAR (GABA_AR) and G protein-coupled GABAR (GABABR) subunit expression was analyzed by qRT-PCR, metabolic activity was determined by nicotinamide adenine dinucleotide (NADH)-dependent oxidoreductase assay (XTT), reactive oxygen species (ROS) generation was analyzed by 2′,7′-dichlorodihydrofluorescein diacetate (DCFDA), and interleukin-8 (IL-8) production was analyzed by an enzyme-linked immunosorbent assay (ELISA). HMC3 expressed several neuroreceptors such as subunits of the GABA_A receptor (GABA_AR). HMC3 constitutively produce IL-8 and ROS. Both muscimol and GABA stimulated HMC3 to produce more IL-8 but had no effect on constitutive ROS production. GABA and muscimol altered the morphology and Iba1 localization of HMC3. GABA, but not muscimol, increased HMC3 metabolic activity. Similarly, AME-1 induced HMC3 to produce more IL-8 but not ROS and altered cell morphology and Iba1 localization. GABA induction of IL-8 was blocked by bicuculline, an antagonist of GABA_AR. AME-1-induced production of IL-8 was not blocked by bicuculline, suggesting that AME-1’s effect on HMC3 was independent of GABA_AR. In conclusion, these data show that GABA and GABA agonists stimulate HMC3 to increase their production of IL-8. Mixtures that contain GABA and muscimol, such as AME-1, have similar effects on HMC3 that are independent of GABA_AR. Full article