RESUMO
Polyphenols have been well-established to exert sedative-hypnotic effects in psychopharmacology. Lime (Citrus aurantifolia) peel is rich in biologically active polyphenols; however, the effects of lime peel extract on sleep have not yet been demonstrated. A comparison was conducted in mice, between the sleep-promoting effects of a standardized lime peel supplement (SLPS) and a well-known hypnotic drug, zolpidem, and its hypnotic mechanism was investigated using in vivo and in vitro assays. The effects of SLPS on sleep were assessed using a pentobarbital-induced sleep test and sleep architecture analysis based on recording electroencephalograms and electromyograms. Additionally, a GABAA receptor binding assay, electrophysiological measurements, and in vivo animal models were used to elucidate the hypnotic mechanism. SLPS (200 and 400â¯mg/kg) was found to significantly decrease sleep latency and increase the amount of non-rapid eye movement sleep without altering delta activity. The hypnotic effects of SLPS were attributed to its flavonoid-rich ethyl acetate fraction. SLPS had a binding affinity to the GABA-binding site of the GABAA receptor and directly activated the GABAA receptors. The hypnotic effects and GABAA receptor activity of SLPS were completely blocked by bicuculline, a competitive antagonist of the GABAA receptor, in both in vitro and in vivo assays. To the best of our knowledge, this study is the first to demonstrate the hypnotic effects of SLPS, which acts via the GABA-binding site of the GABAA receptor. Our results suggest that lime peel, a by-product abundantly generated during juice processing, can potentially be used as a novel sedative-hypnotic.
Assuntos
Hipnóticos e Sedativos , Extratos Vegetais , Receptores de GABA-A , Sono , Animais , Receptores de GABA-A/metabolismo , Receptores de GABA-A/efeitos dos fármacos , Masculino , Extratos Vegetais/farmacologia , Camundongos , Hipnóticos e Sedativos/farmacologia , Sono/efeitos dos fármacos , Citrus/química , Suplementos Nutricionais , Zolpidem/farmacologia , Eletroencefalografia , Citrus aurantiifolia/química , Camundongos Endogâmicos ICR , Agonistas de Receptores de GABA-A/farmacologiaRESUMO
Depression is among the most common psychiatric illnesses, which imposes a major socioeconomic burden on patients, caregivers, and the public health system. Treatment with classical antidepressants (e.g. tricyclic antidepressants and selective serotonine reuptake inhibitors), which primarily affect monoaminergic systems has several limitations, such as delayed onset of action and moderate efficacy in a relatively large proportion of depressed patients. Furthermore, depression is highly heterogeneus, and its different subtypes, including post-partum depression, involve distinct neurobiology, warranting a differential approach to pharmacotherapy. Given these shortcomings, the need for novel antidepressants that are superior in efficacy and faster in onset of action is fully justified. The development and market introduction of rapid-acting antidepressants has accelerated in recent years. Some of these new antidepressants act through the GABAergic system. In this review, we discuss the discovery, efficacy, and limitations of treatment with classic antidepressants. We provide a detailed discussion of GABAergic neurotransmission, with a special focus on GABAA receptors, and possible explanations for the mood-enhancing effects of GABAergic medications (in particular neurosteroids acting at GABAA receptors), and, ultimately, we present the most promising molecules belonging to this family which are currently used in clinical practice or are in late phases of clinical development.
Assuntos
Antidepressivos , Receptores de GABA-A , Humanos , Receptores de GABA-A/metabolismo , Receptores de GABA-A/efeitos dos fármacos , Antidepressivos/uso terapêutico , Antidepressivos/farmacologia , Animais , Depressão/tratamento farmacológico , Depressão/metabolismoRESUMO
Autism spectrum disorders (ASDs) are characterized by core behavioral symptoms in the domains of sociability, language/communication, and repetitive or stereotyped behaviors. Deficits in the prefrontal and hippocampal excitatory/inhibitory balance due to a functional loss of GABAergic interneurons are proposed to underlie these symptoms. Increasing the postsynaptic effects of GABA with compounds that selectively modulate GABAergic receptors could be a potential target for treating ASD symptoms. In addition, deficits in GABAergic interneurons have been linked to dopamine (DA) system dysregulation, and, despite conflicting evidence, abnormalities in the DA system activity may underly some ASD symptoms. Here, we investigated whether the positive allosteric modulator of α5-containing GABAA receptors (α5-GABAARs) SH-053-2'F-R-CH3 (10 mg/kg) attenuates behavioral abnormalities in rats exposed to valproic acid (VPA) in utero, an established risk factor for autism. We also evaluated if animals exposed to VPA in utero present changes in the ventral tegmental area (VTA) DA system activity using in vivo electrophysiology and if SH-053-2'F-R-CH3 could attenuate these changes. SH-053-2'F-R-CH3 was administered intraperitoneally 30 min before each behavioral test and electrophysiology. In utero VPA exposure caused male and female rats to present increased repetitive behavior (self-grooming) in early adolescence and deficits in social interaction in adulthood. Male, but not female VPA rats, also presented deficits in recognition memory as adults. SH-053-2'F-R-CH3 attenuated the impairments in sociability and cognitive function in male VPA-exposed rats without attenuating the decreased social interaction in females. Adult male and female VPA-exposed rats also showed an increased VTA DA neuron population activity, which was not changed by SH-053-2'F-R-CH3. Despite sex differences, our findings indicate that α5-GABAARs positive allosteric modulators may effectively attenuate some core ASD symptoms.
Assuntos
Efeitos Tardios da Exposição Pré-Natal , Receptores de GABA-A , Comportamento Social , Ácido Valproico , Animais , Feminino , Ácido Valproico/farmacologia , Ratos , Masculino , Gravidez , Receptores de GABA-A/efeitos dos fármacos , Dopamina/metabolismo , Transtorno do Espectro Autista/induzido quimicamente , Área Tegmentar Ventral/efeitos dos fármacos , Área Tegmentar Ventral/fisiopatologia , Ratos Sprague-Dawley , Regulação Alostérica/efeitos dos fármacos , Modelos Animais de Doenças , Comportamento Animal/efeitos dos fármacos , Disfunção Cognitiva/induzido quimicamente , Disfunção Cognitiva/fisiopatologiaRESUMO
Recent advances in genetic diagnosis identified variants in genes encoding GABAA receptors as causative for genetic epilepsy. Here, we selected eight disease-associated variants in the α1 subunit of GABAA receptors causing mild to severe clinical phenotypes and showed that they are loss of function, mainly by reducing the folding and surface trafficking of the α1 protein. Furthermore, we sought client protein-specific pharmacological chaperones to restore the function of pathogenic receptors. Applications of positive allosteric modulators, including Hispidulin and TP003, increase the functional surface expression of the α1 variants. Mechanism of action study demonstrated that they enhance the folding, assembly, and trafficking and reduce the degradation of GABAA variants without activating the unfolded protein response in HEK293T cells and human iPSC-derived neurons. Since these compounds cross the blood-brain barrier, such a pharmacological chaperoning strategy holds great promise to treat genetic epilepsy in a GABAA receptor-specific manner.
Assuntos
Epilepsia , Proteostase , Receptores de GABA-A , Humanos , Receptores de GABA-A/genética , Receptores de GABA-A/metabolismo , Receptores de GABA-A/efeitos dos fármacos , Proteostase/efeitos dos fármacos , Epilepsia/tratamento farmacológico , Epilepsia/genética , Epilepsia/metabolismo , Células HEK293 , Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Células-Tronco Pluripotentes Induzidas/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismoRESUMO
Anxiety is a commonly prevailing psychological disorder that requires effective treatment, wherein phytopharmaceuticals and nutraceuticals could offer a desirable therapeutic profile. Hybanthus enneaspermus (L.) F. Muell. is a powerful medicinal herb, reportedly effective against several ailments, including psychological disorders. The current research envisaged evaluating the anxiolytic potential of the ethanolic extract of Hybanthus enneaspermus (EEHE) and its toluene insoluble biofraction (ITHE) employing experimental and computational approaches. Elevated Plus Maze, Light and Dark Transition, Mirror Chamber, Hole board and Open field tests were used as screening models to assess the antianxiety potential of 100, 200 and 400 mg/kg body weight of EEHE and ITHE in rats subjected to social isolation, using Diazepam as standard. The brains of rats exhibiting significant anxiolytic activity were dissected for histopathological and biochemical studies. Antioxidant enzymes like catalase, superoxide dismutase, glutathione-S-transferase, glutathione peroxidase, glutathione reductase; and neurotransmitters viz. monoamines (serotonin, noradrenaline, dopamine), Gamma-aminobutyric acid (GABA), and glutamate were quantified in the different regions of rats' brain (cortex, hippocampus, pons, medulla oblongata, cerebellum). Chromatographic techniques were used to isolate phytoconstituents from the fraction exhibiting significant activity that were characterized by spectroscopic methods and subjected to in silico molecular docking. ITHE at 400 mg/kg body weight significantly mitigated anxiety in all the screening models (p < 0.05), reduced the inflammatory vacuoles and necrosis (p < 0.05) and potentiated the antioxidant enzymes (p < 0.05). It enhanced the monoamines and GABA levels while attenuating glutamate levels (p < 0.01) in the brain. Three significant flavonoids viz. Quercitrin, Rutin and Hesperidin were isolated from ITHE. In silico docking studies of these flavonoids revealed that the compounds exhibited substantial binding to the GABAA receptor. ITHE displayed a promising pharmacological profile in combating anxiety and modulating oxidative stress, attributing its therapeutic virtues to the flavonoids present.
Assuntos
Ansiolíticos , Ansiedade , Extratos Vegetais , Ratos Wistar , Animais , Ansiolíticos/farmacologia , Ansiolíticos/isolamento & purificação , Ansiolíticos/uso terapêutico , Ansiolíticos/química , Ratos , Extratos Vegetais/farmacologia , Extratos Vegetais/isolamento & purificação , Extratos Vegetais/uso terapêutico , Extratos Vegetais/química , Ansiedade/tratamento farmacológico , Ansiedade/metabolismo , Masculino , Simulação de Acoplamento Molecular , Receptores de GABA-A/metabolismo , Receptores de GABA-A/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Encéfalo/metabolismo , Aprendizagem em Labirinto/efeitos dos fármacosRESUMO
The reliable induction of long-term potentiation (LTP) in the dentate gyrus (DG) in vitro requires the blockade of the γ-aminobutyric acid A (GABAA) receptor. In these studies we examined the effectiveness of the specific GABAA receptor antagonist bicuculline methiodide (BMI) in facilitating LTP in the DG from hippocampal slices obtained from either C57Bl/6 mice or Sprague-Dawley rats, two species commonly used for electrophysiology. In the C57Bl/6 mice, maximal short-term potentiation and LTP in the DG were produced with a concentration of 5 µM BMI. In contrast, a concentration of 10 µM BMI was required to produce maximal short-term potentiation and LTP in the DG of Sprague-Dawley rats. These results reveal that there are species differences in the optimal amount of BMI required to produce robust and reliable LTP in the rodent DG in vitro and highlight the need to take consideration of the species being used when choosing concentrations of pharmacological agents to employ for electrophysiological use.NEW & NOTEWORTHY In this report we provide specific neurophysiological evidence for concentrations of GABAA antagonist required to study long-term potentiation in the medial perforant pathway of the dentate gyrus. Two commonly used species, Sprague-Dawley rats and C57Bl/6 mice, require different concentrations of bicuculline methiodide to induce optimal short-term and long-term potentiation.
Assuntos
Bicuculina , Giro Denteado , Antagonistas de Receptores de GABA-A , Potenciação de Longa Duração , Camundongos Endogâmicos C57BL , Ratos Sprague-Dawley , Animais , Potenciação de Longa Duração/efeitos dos fármacos , Potenciação de Longa Duração/fisiologia , Giro Denteado/efeitos dos fármacos , Giro Denteado/fisiologia , Bicuculina/farmacologia , Bicuculina/análogos & derivados , Antagonistas de Receptores de GABA-A/farmacologia , Camundongos , Ratos , Masculino , Receptores de GABA-A/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Receptores de GABA-A/fisiologia , Especificidade da EspécieRESUMO
We previously showed that the PDE4 inhibitor apremilast reduces ethanol consumption in mice by protein kinase A (PKA) and GABAergic mechanisms. Preventing PKA phosphorylation of GABAA ß3 subunits partially blocked apremilast-mediated decreases in drinking. Here, we produced Gabrb1-S409A mice to render GABAA ß1 subunits resistant to PKA-mediated phosphorylation. Mass spectrometry confirmed the presence of the S409A mutation and lack of changes in ß1 subunit expression or phosphorylation at other residues. ß1-S409A male and female mice did not differ from wild-type C57BL/6J mice in expression of Gabrb1, Gabrb2, or Gabrb3 subunits or in behavioral characteristics. Apremilast prolonged recovery from ethanol ataxia to a greater extent in Gabrb1-S409A mice but prolonged recovery from zolpidem and propofol to a similar extent in both genotypes. Apremilast shortened recovery from diazepam ataxia in wild-type but prolonged recovery in Gabrb1-S409A mice. In wild-type mice, the PKA inhibitor H89 prevented apremilast modulation of ataxia by ethanol and diazepam, but not by zolpidem. In Gabrb1-S409A mice, inhibiting PKA or EPAC2 (exchange protein directly activated by cAMP) partially reversed apremilast potentiation of ethanol, diazepam, and zolpidem ataxia. Apremilast prevented acute tolerance to ethanol ataxia in both genotypes, but there were no genotype differences in ethanol consumption before or after apremilast. In contrast to results in Gabrb3-S408A/S409A mice, PKA phosphorylation of ß1-containing GABAA receptors is not required for apremilast's effects on acute tolerance or on ethanol consumption but is required for its ability to decrease diazepam intoxication. Besides PKA we identified EPAC2 as an additional cAMP-dependent mechanism by which apremilast regulates responses to GABAergic drugs.
Assuntos
Proteínas Quinases Dependentes de AMP Cíclico , Etanol , Camundongos Endogâmicos C57BL , Inibidores da Fosfodiesterase 4 , Receptores de GABA-A , Talidomida , Animais , Talidomida/farmacologia , Talidomida/análogos & derivados , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Inibidores da Fosfodiesterase 4/farmacologia , Masculino , Feminino , Etanol/farmacologia , Camundongos , Receptores de GABA-A/genética , Receptores de GABA-A/metabolismo , Receptores de GABA-A/efeitos dos fármacos , Técnicas de Introdução de Genes , Fosforilação/efeitos dos fármacos , Ataxia/genética , Consumo de Bebidas Alcoólicas/tratamento farmacológico , Consumo de Bebidas Alcoólicas/genética , Camundongos Transgênicos , Diazepam/farmacologiaRESUMO
Zolpidem, a non-benzodiazepine hypnotic, is primarily used to treat insomnia. In a previous study, pior treatment with non-benzodiazepine receptor agonists was associated with inflammation. The present study aimed to clarify the association between the effects of zolpidem and inflammation in mice treated with lipopolysaccharide (LPS), a known model of inflammation. We assessed the zolpidem-induced loss of righting reflex (LORR) duration 24 h after LPS treatment in mice. Additionally, the expressions of γ-aminobutyric acid (GABA)A receptor subunit and K+-Cl- cotransporter isoform 2 (KCC2) mRNA in the hippocampus and frontal cortex were examined in LPS-treated mice. Pretreatment with LPS was associated with significantly prolonged duration of zolpidem-induced LORR compared to control mice. This effect was significantly attenuated by administering bicuculline, a GABAA receptor antagonist, or flumazenil, a benzodiazepine receptor antagonist, in LPS-treated mice. Compared to controls, LPS-treated mice showed no significant change in the expression of GABAA receptor subunits in the hippocampus or frontal cortex. Bumetanide, an Na+-K+-2Cl- cotransporter isoform 1 blocker, attenuated the extended duration of zolpidem-induced LORR observed in LPS-treated mice. LPS significantly decreased Kcc2 mRNA expression in the hippocampus and the frontal cortex. These findings suggest that inflammation increases zolpidem-induced LORR, possibly through a reduction in KCC2 expression.
Assuntos
Lipopolissacarídeos , Piridinas , Receptores de GABA-A , Reflexo de Endireitamento , Simportadores , Zolpidem , Animais , Zolpidem/farmacologia , Camundongos , Piridinas/farmacologia , Masculino , Receptores de GABA-A/metabolismo , Receptores de GABA-A/efeitos dos fármacos , Simportadores/genética , Simportadores/metabolismo , Reflexo de Endireitamento/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Cotransportadores de K e Cl- , Hipnóticos e Sedativos/farmacologia , Inflamação/induzido quimicamente , Lobo Frontal/efeitos dos fármacos , Lobo Frontal/metabolismoRESUMO
OBJECTIVES: To investigate roles of brain carbon monoxide (CO), an endogenous gasotransmitter, in regulation of the rat micturition reflex. METHODS: In urethane-anesthetized (0.8 g/kg, ip) male rats, evaluation of urodynamic parameters was started 1 h before intracerebroventricular administration of CORM-3 (CO donor) or ZnPP (non-selective inhibitor of heme oxygenase, a CO producing enzyme) and continued for 2 h after the administration. We also investigated effects of centrally pretreated SR95531 (GABAA receptor antagonist) or SCH50911 (GABAB receptor antagonist) on the CORM-3-induced response. RESULTS: CORM-3 significantly prolonged intercontraction intervals (ICIs) without changing maximal voiding pressure (MVP), while ZnPP significantly shortened ICI and reduced single-voided volume and bladder capacity without affecting MVP, post-voided residual volume, or voiding efficiency. The ZnPP-induced ICI shortening was reversed by CORM-3. The CORM-3-induced ICI prolongation was significantly attenuated by centrally pretreated SR95531 or SCH50911, respectively. CONCLUSIONS: Brain CO can suppress the rat micturition reflex through brain γ-aminobutyric acid (GABA) receptors.
Assuntos
Encéfalo , Monóxido de Carbono , Ratos Sprague-Dawley , Bexiga Urinária , Micção , Animais , Masculino , Micção/efeitos dos fármacos , Ratos , Monóxido de Carbono/farmacologia , Encéfalo/efeitos dos fármacos , Encéfalo/fisiologia , Bexiga Urinária/efeitos dos fármacos , Bexiga Urinária/fisiologia , Reflexo/efeitos dos fármacos , Compostos Organometálicos/farmacologia , Heme Oxigenase (Desciclizante)/metabolismo , Heme Oxigenase (Desciclizante)/antagonistas & inibidores , Urodinâmica/efeitos dos fármacos , Receptores de GABA-A/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Receptores de GABA/efeitos dos fármacos , Receptores de GABA/metabolismoRESUMO
There is a critical need for safer and better-tolerated alternatives to address the current limitations of antidepressant treatments for major depressive disorder. Recently, drugs targeting the GABA system via α5-containing GABAA receptors (α5-GABAAR) as negative allosteric modulators (α5-NAMs) have shown promise in alleviating stress-related behaviors in preclinical studies, suggesting that α5-NAMs may have translational relevance as novel antidepressant medications. Here, we evaluated the efficacy of Basmisanil, an α5-NAM that has been evaluated in Phase 2 clinical studies as a cognitive enhancer, in a battery of behavioral tests relevant to coping strategies, motivation, and aversion in male mice, along with plasma and brain pharmacokinetic measurements. Our findings reveal that Basmisanil induces dose-dependent rapid antidepressant-like responses in the forced swim test and sucrose splash test without promoting locomotor stimulating effects. Furthermore, Basmisanil elicits sustained behavioral responses in the female urine sniffing test and sucrose splash test, observed 24 h and 48 h post-treatment, respectively. Bioanalysis of plasma and brain samples confirms effective blood-brain barrier penetration by Basmisanil and extrapolation to previously published data suggest that effects were observed at doses (10 and 30 mg/kg i.p.) corresponding to relatively modest levels of α5-GABAAR occupancy (40-65 %). These results suggest that Basmisanil exhibits a combination of rapid and sustained antidepressant-like effects highlighting the potential of α5-NAMs as a novel therapeutic strategy for depression.
Assuntos
Antidepressivos , Receptores de GABA-A , Animais , Feminino , Masculino , Camundongos , Antidepressivos/farmacologia , Antidepressivos/farmacocinética , Comportamento Animal/efeitos dos fármacos , Barreira Hematoencefálica/metabolismo , Barreira Hematoencefálica/efeitos dos fármacos , Encéfalo/metabolismo , Encéfalo/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Receptores de GABA-A/metabolismo , Receptores de GABA-A/efeitos dos fármacos , Morfolinas/farmacologia , Oxazóis/farmacologia , Piridinas/farmacologiaRESUMO
BACKGROUND: GABA, a key inhibitory neurotransmitter, has synaptic and extrasynaptic receptors on the postsynaptic neuron. Background GABA, which spills over from the synaptic cleft, acts on extrasynaptic delta subunit containing GABAA receptors. The role of extrasynaptic GABAergic input in migraine is unknown. We investigated the susceptibility to valid migraine-provoking substances with clinically relevant behavioral readouts in Genetic Absence Epilepsy of Rats Strasbourg (GAERS), in which the GABAergic tonus was altered. Subsequently, we screened relevant GABAergic mechanisms in Wistar rats by pharmacological means to identify the mechanisms. METHODS: Wistar and GAERS rats were administered nitroglycerin (10 mg/kg) or levcromakalim (1 mg/kg). Mechanical allodynia and photophobia were assessed using von Frey monofilaments and a dark-light box. Effects of GAT-1 blocker tiagabine (5 mg/kg), GABAB receptor agonist baclofen (2 mg/kg), synaptic GABAA receptor agonist diazepam (1 mg/kg), extrasynaptic GABAA receptor agonists gaboxadol (4 mg/kg), and muscimol (0.75 mg/kg), T-type calcium channel blocker ethosuximide (100 mg/kg) or synaptic GABAA receptor antagonist flumazenil (15 mg/kg) on levcromakalim-induced migraine phenotype were screened. RESULTS: Unlike Wistar rats, GAERS exhibited no reduction in mechanical pain thresholds or light aversion following nitroglycerin or levcromakalim injection. Ethosuximide did not reverse the resistant phenotype in GAERS, excluding the role of T-type calcium channel dysfunction in this phenomenon. Tiagabine prevented levcromakalim-induced mechanical allodynia in Wistar rats, suggesting a key role in enhanced GABA spillover. Baclofen did not alleviate mechanical allodynia. Diazepam failed to mitigate levcromakalim-induced migraine phenotype. Additionally, the resistant phenotype in GAERS was not affected by flumazenil. Extrasynaptic GABAA receptor agonists gaboxadol and muscimol inhibited periorbital allodynia in Wistar rats. CONCLUSION: Our study introduced a rat strain resistant to migraine-provoking agents and signified a critical involvement of extrasynaptic δGABAergic receptors. Extrasynaptic δ GABAA receptors, by mediating constant background inhibition on the excitability of neurons, stand as a novel drug target with a therapeutic potential in migraine.
Assuntos
Transtornos de Enxaqueca , Fenótipo , Ratos Wistar , Receptores de GABA-A , Animais , Transtornos de Enxaqueca/metabolismo , Transtornos de Enxaqueca/tratamento farmacológico , Transtornos de Enxaqueca/fisiopatologia , Ratos , Receptores de GABA-A/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Masculino , Modelos Animais de Doenças , Hiperalgesia/tratamento farmacológico , Hiperalgesia/metabolismo , Epilepsia Tipo Ausência/tratamento farmacológico , Epilepsia Tipo Ausência/fisiopatologia , Nitroglicerina/farmacologia , Nitroglicerina/toxicidade , Fotofobia/etiologia , Fotofobia/fisiopatologiaRESUMO
OBJECTIVE: North Sea Progressive Myoclonus Epilepsy (NS-PME) is a rare genetic disorder characterized by ataxia, myoclonus and seizures with a progressive course. Although the cause of NS-PME is known, namely a homozygous mutation in the GOSR2 gene (c.430â¯G>T; p. Gly144Trp), sufficient treatment is lacking. Despite combinations of on average 3-5 anti-seizure medications (ASMs), debilitating myoclonus and seizures persist. Here we aimed to gain insight into the most effective anti-convulsive target in NS-PME by evaluating the individual effects of ASMs in a NS-PME Drosophila model. METHOD: A previously generated Drosophila model for NS-PME was used displaying progressive heat-sensitive seizures. We used this model to test 1. a first-generation ASM (sodium barbital), 2. common ASMs used in NS-PME (clonazepam, valproic acid, levetiracetam, ethosuximide) and 3. a novel third-generation ASM (ganaxolone) with similar mode of action to sodium barbital. Compounds were administered by adding them to the food in a range of concentrations. After 7 days of treatment, the percentage of heat-induced seizures was determined and compared to non-treated but affected controls. RESULTS: As previously reported in the NS-PME Drosophila model, sodium barbital resulted in significant seizure suppression, with increasing effect at higher dosages. Of the commonly prescribed ASMs, clonazepam and ethosuximide resulted in significant seizure suppression, whereas both valproic acid and levetiracetam did not show any changes in seizures. Interestingly, ganaxolone did result in seizure suppression as well. CONCLUSION: Of the six drugs tested, three of the four that resulted in seizure suppression (sodium barbital, clonazepam, ganaxolone) are primary known for their direct effect on GABAA receptors. This suggests that GABAA could be a potentially important target in the treatment of NS-PME. Consequently, these findings add rationale to the exploration of the clinical effect of ganaxolone in NS-PME and other progressive myoclonus epilepsies.
Assuntos
Anticonvulsivantes , Modelos Animais de Doenças , Drosophila , Epilepsias Mioclônicas Progressivas , Animais , Anticonvulsivantes/uso terapêutico , Anticonvulsivantes/farmacologia , Epilepsias Mioclônicas Progressivas/genética , Epilepsias Mioclônicas Progressivas/tratamento farmacológico , Animais Geneticamente Modificados , Receptores de GABA-A/genética , Receptores de GABA-A/efeitos dos fármacosRESUMO
Objective: To investigate the molecular mechanism of sevoflurane affecting the development of the offspring's nervous system through the GABAAR/Sirt 1 pathway. Methods: Pregnant rats were obtained by mating females and males, and were randomly divided into 3 h sevoflurane (2.3% sevoflurane anesthesia for 3 h), 6 h sevoflurane (2.3% sevoflurane anesthesia for 6 h), Sirt-1 activator-SRT1720 (10 mg/kg SRT1720), 6 h sevoflurane+SRT1720 (10 mg/kg SRT1720) and control groups) group and control group, 31-day-old littermates were taken out and their learning and memory functions were examined by the water maze experiment; the heads were severed to remove the brains, and the kits were used to detect the levels of 5-HT and Ach in the brain tissue; the hippocampal tissues of the littermates were isolated, and neuronal damage in the hippocampal tissues was assessed by Nissen staining; neuronal apoptosis in the hippocampal tissues was detected by TUNEL staining; and GABAAR in the hippocampal tissues was detected by Western blot. GABAAR, Sirt-1, and apoptosis-related proteins (Caspase-3, BCL-2, BAX) in hippocampal tissue. Results: Compared with the control group, the 3 h sevoflurane group and the 6 h sevoflurane group neurons were arranged sparsely, the cells appeared to be swollen, the evasion latency, the apoptosis rate of neurons, the expression of Caspase-3, and BAX increased significantly, and the number of crossing the plateau, the level of 5-HT and Ach in the brain tissues, and the expression of GABAAR, Sirt-1, and BCL-2 were decreased significantly, and the differences existed between the groups (P < .5); compared with the 6 h sevoflurane group, neuronal morphological changes in the hippocampal tissue of the 6 h sevoflurane+SRT1720 group were improved, with a significant decrease in the evasion latency, neuronal apoptosis rate, expression of Caspase-3 and BAX, and a significant increase in the number of traversing platforms, brain tissue 5-HT, Ach level, GABAAR, Sirt-1, and BCL-2 expression (P < .5); compared with the SRT1720 group, the neurons in the 6 h sevoflurane + SRT1720 group were sparsely arranged, with a significant increase in evasion latency, neuronal apoptosis rate, caspase-3, BAX expression, and a significant decrease in the number of traversing platforms, brain tissue 5-HT, Ach level, GABAAR, Sirt-1, and BCL-2 expression (P < .5 ). Conclusion: Sevoflurane can affect the neurological development of rat offspring, which may be related to the inhibition of Sirt-1 expression.
Assuntos
Sevoflurano , Sirtuína 1 , Sevoflurano/farmacologia , Animais , Sirtuína 1/metabolismo , Ratos , Feminino , Gravidez , Anestésicos Inalatórios/farmacologia , Receptores de GABA-A/metabolismo , Receptores de GABA-A/efeitos dos fármacos , Masculino , Ratos Sprague-Dawley , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Apoptose/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacosRESUMO
BACKGROUND: Dysfunctional sensory gating in anxiety disorders, indexed by the failure to inhibit the P50 event-related potential (ERP) to repeated stimuli, has been linked to deficits in the major inhibitory neurotransmitter γ-aminobutyric acid (GABA). AIMS/METHODS: This study, conducted in 30 healthy volunteers, examined the acute effects of GABAA (lorazepam: 1 mg) and GABAB receptor (baclofen: 10 mg) agonists on P50 measures of auditory sensory gating within a paired-stimulus (S1-S2) paradigm and assessed changes in gating in relation to self-ratings of anxiety. RESULTS: Compared to placebo, lorazepam reduced ERP indices of sensory gating by attenuating response to S1. Although not directly impacting P50 inhibition, baclofen-induced changes in gating (relative to placebo) were negatively correlated with trait but not state anxiety. CONCLUSIONS: These preliminary findings support the involvement of GABA in sensory gating and tentatively suggest a role for GABAB receptor signaling in anxiety-associated gating dysregulation.
Assuntos
Ansiedade , Baclofeno , Agonistas dos Receptores de GABA-B , Lorazepam , Receptores de GABA-B , Filtro Sensorial , Humanos , Masculino , Feminino , Adulto , Baclofeno/farmacologia , Lorazepam/farmacologia , Agonistas dos Receptores de GABA-B/farmacologia , Ansiedade/metabolismo , Adulto Jovem , Filtro Sensorial/efeitos dos fármacos , Receptores de GABA-B/metabolismo , Receptores de GABA-B/efeitos dos fármacos , Agonistas de Receptores de GABA-A/farmacologia , Voluntários Saudáveis , Método Duplo-Cego , Potenciais Evocados Auditivos/efeitos dos fármacos , Potenciais Evocados Auditivos/fisiologia , Receptores de GABA-A/metabolismo , Receptores de GABA-A/efeitos dos fármacos , AdolescenteRESUMO
Tonic inhibition in mouse hippocampal CA1 pyramidal neurons is mediated by α5 subunit-containing γ-aminobutyric acid type A receptors. By Caraiscos VB, Elliott EM, You-Ten KE, Cheng VY, Belelli D, Newell JG, Jackson MF, Lambert JJ, Rosahl TW, Wafford KA, MacDonald JF, Orser BA. Proc Natl Acad Sci U S A 2004; 101:3662-7. Reprinted with permission. In this Classic Paper Revisited, the author recounts the scientific journey leading to a report published in the Proceedings of the National Academy of Sciences (PNAS) and shares several personal stories from her formative years and "research truths" that she has learned along the way. Briefly, the principal inhibitory neurotransmitter in the brain, γ-aminobutyric acid (GABA), was conventionally thought to regulate cognitive processes by activating synaptic GABA type A (GABAA) receptors and generating transient inhibitory synaptic currents. However, the author's laboratory team discovered a novel nonsynaptic form of tonic inhibition in hippocampal pyramidal neurons, mediated by extrasynaptic GABAA receptors that are pharmacologically distinct from synaptic GABAA receptors. This tonic current is highly sensitive to most general anesthetics, including sevoflurane and propofol, and likely contributes to the memory-blocking properties of these drugs. Before the publication in PNAS, the subunit composition of GABAA receptors that generate the tonic current was unknown. The team's research showed that GABAA receptors containing the α5 subunit (α5GABAARs) generated the tonic inhibitory current in hippocampal neurons. α5GABAARs are highly sensitive to GABA, desensitize slowly, and are thus well suited for detecting low, persistent, ambient concentrations of GABA in the extracellular space. Interest in α5GABAARs has surged since the PNAS report, driven by their pivotal roles in cognitive processes and their potential as therapeutic targets for treating various neurologic disorders.
Assuntos
Receptores de GABA-A , Animais , Receptores de GABA-A/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Camundongos , Células Piramidais/efeitos dos fármacos , Células Piramidais/fisiologia , Células Piramidais/metabolismo , Humanos , Sinapses/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
In this study, the electrophysiological and biochemical consequences of repeated exposure to morphine in male rats on glutamatergic synaptic transmission, synaptic plasticity, the expression of GABA receptors and glutamate receptors at the temporoammonic-CA1 synapse along the longitudinal axis of the hippocampus (dorsal, intermediate, ventral, DH, IH, VH, respectively) were investigated. Slice electrophysiological methods, qRT-PCR, and western blotting techniques were used to characterize synaptic plasticity properties. We showed that repeated morphine exposure (RME) reduced excitatory synaptic transmission and ability for long-term potentiation (LTP) in the VH as well as eliminated the dorsoventral difference in paired-pulse responses. A decreased expression of NR2B subunit in the VH and an increased expression GABAA receptor of α1 and α5 subunits in the DH were observed following RME. Furthermore, RME did not affect the expression of NR2A, AMPA receptor subunits, and γ2GABAA and GABAB receptors in either segment of the hippocampus. In sum, the impact of morphine may differ depending on the region of the hippocampus studied. A distinct change in the short- and long-term synaptic plasticity along the hippocampus long axis due to repeated morphine exposure, partially mediated by a change in the expression profile of glutamatergic receptor subunits. These findings can be useful in further understanding the cellular mechanism underlying deficits in information storage and, more generally, cognitive processes resulting from chronic opioid abuse.
Assuntos
Morfina , Plasticidade Neuronal , Ratos Sprague-Dawley , Animais , Masculino , Morfina/farmacologia , Plasticidade Neuronal/efeitos dos fármacos , Plasticidade Neuronal/fisiologia , Região CA1 Hipocampal/efeitos dos fármacos , Região CA1 Hipocampal/metabolismo , Ratos , Potenciação de Longa Duração/efeitos dos fármacos , Potenciação de Longa Duração/fisiologia , Hipocampo/efeitos dos fármacos , Hipocampo/metabolismo , Entorpecentes/farmacologia , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologia , Receptores de GABA-A/metabolismo , Receptores de GABA-A/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Receptores de GABA/metabolismo , Receptores de GABA/efeitos dos fármacosRESUMO
Dimdazenil (Junoenil®) is a small-molecule, oral, partial positive allosteric modulator of the gamma-aminobutyric acid (GABA)A receptor that is being developed by Zhejiang Jingxin Pharmaceutical in collaboration with Evotec for the treatment of insomnia. Dimdazenil is designed to overcome issues associated with full GABAA receptor agonists, such as tolerance, withdrawal symptoms and associated adverse effects. On 29 November 2023, dimdazenil oral capsules received approval in China for the short-term treatment of insomnia. This article summarizes the milestones in the development of dimdazenil leading to this first approval for insomnia.
Assuntos
Aprovação de Drogas , Distúrbios do Início e da Manutenção do Sono , Humanos , Distúrbios do Início e da Manutenção do Sono/tratamento farmacológico , China , Moduladores GABAérgicos/farmacologia , Moduladores GABAérgicos/uso terapêutico , Moduladores GABAérgicos/efeitos adversos , Moduladores GABAérgicos/administração & dosagem , Receptores de GABA-A/metabolismo , Receptores de GABA-A/efeitos dos fármacos , Administração Oral , Flumazenil/farmacologia , Flumazenil/uso terapêuticoRESUMO
Acid-sensing ion channels (ASICs) are proton-gated ion channels that mediate nociception in the peripheral nervous system and contribute to fear and learning in the central nervous system. Sevanol was reported previously as a naturally-occurring ASIC inhibitor from thyme with favorable analgesic and anti-inflammatory activity. Using electrophysiological methods, we found that in the high micromolar range, the compound effectively inhibited homomeric ASIC1a and, in sub- and low-micromolar ranges, positively modulated the currents of α1ß2γ2 GABAA receptors. Next, we tested the compound in anxiety-related behavior models using a targeted delivery into the hippocampus with parallel electroencephalographic measurements. In the open field, 6 µM sevanol reduced both locomotor and θ-rhythmic activity similar to GABA, suggesting a primary action on the GABAergic system. At 300 µM, sevanol markedly suppressed passive avoidance behavior, implying alterations in conditioned fear memory. The observed effects could be linked to distinct mechanisms involving GABAAR and ASIC1a. These results elaborate the preclinical profile of sevanol as a candidate for drug development and support the role of ASIC channels in fear-related functions of the hippocampus.
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Thymus (Planta) , Canais Iônicos Sensíveis a Ácido , Medo/efeitos dos fármacos , Ácido gama-Aminobutírico , Hipocampo/efeitos dos fármacos , Receptores de GABA-A/efeitos dos fármacos , Thymus (Planta)/químicaRESUMO
Type A γ-aminobutyric acid receptors (GABAARs) are the principal inhibitory receptors in the brain and the target of a wide range of clinical agents, including anaesthetics, sedatives, hypnotics and antidepressants1-3. However, our understanding of GABAAR pharmacology has been hindered by the vast number of pentameric assemblies that can be derived from 19 different subunits4 and the lack of structural knowledge of clinically relevant receptors. Here, we isolate native murine GABAAR assemblies containing the widely expressed α1 subunit and elucidate their structures in complex with drugs used to treat insomnia (zolpidem (ZOL) and flurazepam) and postpartum depression (the neurosteroid allopregnanolone (APG)). Using cryo-electron microscopy (cryo-EM) analysis and single-molecule photobleaching experiments, we uncover three major structural populations in the brain: the canonical α1ß2γ2 receptor containing two α1 subunits, and two assemblies containing one α1 and either an α2 or α3 subunit, in which the single α1-containing receptors feature a more compact arrangement between the transmembrane and extracellular domains. Interestingly, APG is bound at the transmembrane α/ß subunit interface, even when not added to the sample, revealing an important role for endogenous neurosteroids in modulating native GABAARs. Together with structurally engaged lipids, neurosteroids produce global conformational changes throughout the receptor that modify the ion channel pore and the binding sites for GABA and insomnia medications. Our data reveal the major α1-containing GABAAR assemblies, bound with endogenous neurosteroid, thus defining a structural landscape from which subtype-specific drugs can be developed.
Assuntos
Microscopia Crioeletrônica , Neuroesteroides , Receptores de GABA-A , Ácido gama-Aminobutírico , Animais , Camundongos , Sítios de Ligação/efeitos dos fármacos , Depressão Pós-Parto/tratamento farmacológico , Flurazepam/farmacologia , Ácido gama-Aminobutírico/metabolismo , Hipnóticos e Sedativos/farmacologia , Ativação do Canal Iônico/efeitos dos fármacos , Neuroesteroides/metabolismo , Neuroesteroides/farmacologia , Fotodegradação , Pregnanolona/farmacologia , Conformação Proteica/efeitos dos fármacos , Subunidades Proteicas/química , Subunidades Proteicas/efeitos dos fármacos , Subunidades Proteicas/metabolismo , Receptores de GABA-A/química , Receptores de GABA-A/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Receptores de GABA-A/ultraestrutura , Distúrbios do Início e da Manutenção do Sono/tratamento farmacológico , Zolpidem/farmacologiaRESUMO
Animals need to cope with abundant sensory information, and one strategy is to selectively direct attention to only the most relevant part of the environment. Although the cortical networks of selective attention have been studied extensively, its underlying neurotransmitter systems, especially the role of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA), remain less well understood. Increased GABAA receptor activity because of administration of benzodiazepines such as lorazepam is known to slow reactions in cognitive tasks. However, there is limited knowledge about GABAergic involvement in selective attention. Particularly, it is unknown whether increased GABAA receptor activity slows the build-up of selectivity or generally widens attentional focus. To address this question, participants (n = 29) received 1 mg lorazepam and placebo (within-subjects, double-blind) and performed an extended version of the flanker task. The spatial distribution of selective attention was studied by systematically manipulating number and position of incongruent flankers; the temporal build-up was characterized using delta plots. An online task version was presented to an independent, unmedicated sample (n = 25) to verify task effects. Under placebo and in the unmedicated sample, only the number of incongruent flankers, but not their position, influenced RTs. Incongruent flankers impaired RTs more strongly under lorazepam than placebo, especially when adjacent to the target. Delta plot analyses of RT showed that this effect persisted even when participants reacted slowly, indicating that lorazepam-induced impairments in selective attention do not result from simply slowed down build-up of selectivity. Instead, our data indicate that increased GABAA receptor activity widens the attentional focus.