RESUMO
Neurons coordinate inter-tissue protein homeostasis to systemically manage cytotoxic stress. In response to neuronal mitochondrial stress, specific neuronal signals coordinate the systemic mitochondrial unfolded protein response (UPRmt) to promote organismal survival. Yet, whether chemical neurotransmitters are sufficient to control the UPRmt in physiological conditions is not well understood. Here, we show that gamma-aminobutyric acid (GABA) inhibits, and acetylcholine (ACh) promotes the UPRmt in the Caenorhabditis elegans intestine. GABA controls the UPRmt by regulating extra-synaptic ACh release through metabotropic GABAB receptors GBB-1/2. We find that elevated ACh levels in animals that are GABA-deficient or lack ACh-degradative enzymes induce the UPRmt through ACR-11, an intestinal nicotinic α7 receptor. This neuro-intestinal circuit is critical for non-autonomously regulating organismal survival of oxidative stress. These findings establish chemical neurotransmission as a crucial regulatory layer for nervous system control of systemic protein homeostasis and stress responses.
Assuntos
Acetilcolina , Caenorhabditis elegans , Mitocôndrias , Transdução de Sinais , Animais , Acetilcolina/metabolismo , Receptor Nicotínico de Acetilcolina alfa7/metabolismo , Receptor Nicotínico de Acetilcolina alfa7/genética , Caenorhabditis elegans/metabolismo , Caenorhabditis elegans/genética , Caenorhabditis elegans/fisiologia , Proteínas de Caenorhabditis elegans/metabolismo , Proteínas de Caenorhabditis elegans/genética , Ácido gama-Aminobutírico/metabolismo , Intestinos/fisiologia , Mitocôndrias/metabolismo , Neurônios/metabolismo , Estresse Oxidativo , Receptores de GABA-B/metabolismo , Receptores de GABA-B/genética , Estresse Fisiológico , Transmissão Sináptica/fisiologia , Resposta a Proteínas não DobradasRESUMO
BACKGROUND AND OBJECTIVES: Patients with ongoing seizures are usually not allowed to drive. The prognosis for seizure freedom is favorable in patients with autoimmune encephalitis (AIE) with antibodies against NMDA receptor (NMDAR), leucine-rich glioma-inactivated 1 (LGI1), contactin-associated protein-like 2 (CASPR2), and the gamma-aminobutyric-acid B receptor (GABABR). We hypothesized that after a seizure-free period of 3 months, patients with AIE have a seizure recurrence risk of <20% during the subsequent 12 months. This would render them eligible for noncommercial driving according to driving regulations in several countries. METHODS: This retrospective multicenter cohort study analyzed follow-up data from patients aged 15 years or older with seizures resulting from NMDAR-, LGI1-, CASPR2-, or GABABR-AIE, who had been seizure-free for ≥3 months. We used Kaplan-Meier (KM) estimates for the seizure recurrence risk at 12 months for each antibody group and tested for the effects of potential covariates with regression models. RESULTS: We included 383 patients with NMDAR-, 440 with LGI1-, 114 with CASPR2-, and 44 with GABABR-AIE from 14 international centers. After being seizure-free for 3 months after an initial seizure period, we calculated the probability of remaining seizure-free for another 12 months (KM estimate) as 0.89 (95% confidence interval [CI] 0.85-0.92) for NMDAR, 0.84 (CI 0.80-0.88) for LGI1, 0.82 (CI 0.75-0.90) for CASPR2, and 0.76 (CI 0.62-0.93) for GABABR. DISCUSSION: Taking a <20% recurrence risk within 12 months as sufficient, patients with NMDAR-AIE and LGI1-AIE could be considered eligible for noncommercial driving after having been seizure-free for 3 months.
Assuntos
Autoanticorpos , Encefalite , Peptídeos e Proteínas de Sinalização Intracelular , Proteínas de Membrana , Proteínas do Tecido Nervoso , Receptores de GABA-B , Recidiva , Humanos , Feminino , Masculino , Adulto , Peptídeos e Proteínas de Sinalização Intracelular/imunologia , Autoanticorpos/sangue , Pessoa de Meia-Idade , Encefalite/imunologia , Estudos Retrospectivos , Receptores de GABA-B/imunologia , Proteínas do Tecido Nervoso/imunologia , Adulto Jovem , Proteínas de Membrana/imunologia , Receptores de N-Metil-D-Aspartato/imunologia , Convulsões/etiologia , Convulsões/imunologia , Doença de Hashimoto/imunologia , Doença de Hashimoto/sangue , Idoso , Adolescente , Seguimentos , Proteínas/imunologia , Estudos de CoortesRESUMO
The anteroventral bed nucleus of stria terminalis (avBNST) is a limbic forebrain region involved in the regulation of anxiety, and expresses GABAB receptors, which are located at both pre- and post-synaptic sites. However, it is unclear how blockade of these receptors affects anxiety-like behaviors, particularly in Parkinson's disease (PD)-related anxiety. In the present study, unilateral 6-hydroxydopamine (6-OHDA) lesions of the substantia nigra pars compacta in rats induced anxiety-like behaviors, and increased GABA release and decreased glutamate release in the avBNST, as well as decreased level of dopamine (DA) in the basolateral amygdala (BLA). Intra-avBNST injection of pre-synaptic GABAB receptor antagonist CGP36216 produced anxiolytic-like effects, while the injection of post-synaptic GABAB receptor antagonist CGP35348 induced anxiety-like responses in both sham and 6-OHDA rats. Intra-avBNST injection of CGP36216 inhibited the GABAergic neurons and increased GABA/glutamate ratio in the avBNST and increased levels of DA and serotonin (5-HT) in the BLA; conversely, CGP35348 produced opposite effects on the firing activity of avBNST GABAergic neurons and levels of the neurotransmitters in the avBNST and BLA. Moreover, the doses of the antagonists producing significant behavioral effects in 6-OHDA rats were lower than those in sham rats, and the duration of action of the antagonists on the firing rate of the neurons and release of the neurotransmitters was prolonged in 6-OHDA rats. Altogether, these findings suggest that pre- and post-synaptic GABAB receptors in the avBNST are implicated in PD-related anxiety-like behaviors, and degeneration of the nigrostriatal pathway enhances functions and/or upregulates expression of these receptors.
Assuntos
Ansiolíticos , Ansiedade , Antagonistas de Receptores de GABA-B , Oxidopamina , Transtornos Parkinsonianos , Receptores de GABA-B , Núcleos Septais , Animais , Núcleos Septais/efeitos dos fármacos , Núcleos Septais/metabolismo , Masculino , Ansiedade/metabolismo , Antagonistas de Receptores de GABA-B/farmacologia , Ansiolíticos/farmacologia , Ratos , Receptores de GABA-B/metabolismo , Oxidopamina/toxicidade , Transtornos Parkinsonianos/metabolismo , Transtornos Parkinsonianos/induzido quimicamente , Transtornos Parkinsonianos/psicologia , Dopamina/metabolismo , Ácido Glutâmico/metabolismo , Ácido gama-Aminobutírico/metabolismo , Ratos Sprague-Dawley , Serotonina/metabolismo , Complexo Nuclear Basolateral da Amígdala/metabolismo , Complexo Nuclear Basolateral da Amígdala/efeitos dos fármacos , Neurônios GABAérgicos/efeitos dos fármacos , Neurônios GABAérgicos/metabolismo , Compostos OrganofosforadosRESUMO
BACKGROUND: Drug addiction is a social and medical problem that must be urgently addressed. The nucleus accumbens (NAc) is closely related to addiction-related learning memory, and γ-aminobutyric acid type B receptor (GABA B R) is a potential target for the treatment of drug addiction. However, the role of GABA B R activity levels in the NAc in cocaine addiction is unclear. METHODS: In this study, we established an animal model of cocaine dependence, modulated the level of GABA B R activity, applied a conditioned place preference assay (CPP) to assess the role of the NAc in reconsolidation of addiction memory, evaluated learning and memory functions by behavioral experiments, examined the expression of GB1, GB2, cyclic adenosine monophosphate response element binding protein (CREB), p-CREB, protein kinase A (PKA), protein kinase (ERK), and Brain-derived neurotrophic factor (BDNF) in the NAc by molecular biology experiments, and screened differentially significantly expressed genes by transcriptome sequencing. RESULTS: Our study showed that the GABA B receptor agonist baclofen (BLF) had a significant effect on locomotor distance in rats, promoted an increase in GABA levels and significantly inhibited the PKA and ERK1/2/CREB/BDNF signaling pathways. Moreover, transcriptome sequencing showed that GABA B R antagonist intervention identified a total of 21 upregulated mRNAs and 21 downregulated mRNAs. The differentially expressed (DE) mRNA genes were mainly enriched in tyrosine metabolism; however, further study is needed. CONCLUSION: GABA B R activity in the NAc is involved in the regulation of cocaine addiction and may play an important role through key mRNA pathways.
Assuntos
Transtornos Relacionados ao Uso de Cocaína , Núcleo Accumbens , RNA Mensageiro , Ratos Sprague-Dawley , Receptores de GABA-B , Animais , Ratos , Núcleo Accumbens/metabolismo , Núcleo Accumbens/efeitos dos fármacos , Masculino , Receptores de GABA-B/genética , RNA Mensageiro/análise , Transtornos Relacionados ao Uso de Cocaína/metabolismo , Baclofeno/farmacologia , Fator Neurotrófico Derivado do Encéfalo/metabolismo , Fator Neurotrófico Derivado do Encéfalo/genética , Proteína de Ligação ao Elemento de Resposta ao AMP Cíclico/metabolismoRESUMO
Even a transient period of hearing loss during the developmental critical period can induce long-lasting deficits in temporal and spectral perception. These perceptual deficits correlate with speech perception in humans. In gerbils, these hearing loss-induced perceptual deficits are correlated with a reduction of both ionotropic GABAA and metabotropic GABAB receptor-mediated synaptic inhibition in auditory cortex, but most research on critical period plasticity has focused on GABAA receptors. Therefore, we developed viral vectors to express proteins that would upregulate gerbil postsynaptic inhibitory receptor subunits (GABAA, Gabra1; GABAB, Gabbr1b) in pyramidal neurons, and an enzyme that mediates GABA synthesis (GAD65) presynaptically in parvalbumin-expressing interneurons. A transient period of developmental hearing loss during the auditory critical period significantly impaired perceptual performance on two auditory tasks: amplitude modulation depth detection and spectral modulation depth detection. We then tested the capacity of each vector to restore perceptual performance on these auditory tasks. While both GABA receptor vectors increased the amplitude of cortical inhibitory postsynaptic potentials, only viral expression of postsynaptic GABAB receptors improved perceptual thresholds to control levels. Similarly, presynaptic GAD65 expression improved perceptual performance on spectral modulation detection. These findings suggest that recovering performance on auditory perceptual tasks depends on GABAB receptor-dependent transmission at the auditory cortex parvalbumin to pyramidal synapse and point to potential therapeutic targets for developmental sensory disorders.
Assuntos
Córtex Auditivo , Gerbillinae , Perda Auditiva , Animais , Córtex Auditivo/metabolismo , Córtex Auditivo/fisiopatologia , Perda Auditiva/genética , Perda Auditiva/fisiopatologia , Receptores de GABA-B/metabolismo , Receptores de GABA-B/genética , Glutamato Descarboxilase/metabolismo , Glutamato Descarboxilase/genética , Receptores de GABA-A/metabolismo , Receptores de GABA-A/genética , Parvalbuminas/metabolismo , Parvalbuminas/genética , Percepção Auditiva/fisiologia , Células Piramidais/metabolismo , Células Piramidais/fisiologia , Vetores Genéticos/genéticaRESUMO
Although classically recognized as a neurotransmitter, gamma aminobutyric acid (GABA) has also been identified in colonic tumors. Moreover, the gut microbiome represents another potential source of GABA. Both GABAA and GABAB receptors have been implicated in contributing to the effects of GABA in colorectal cancer, with both pro- and anti-tumorigenic functions identified. However, their subunit composition is often overlooked. Studies to date have not addressed whether the GABA-producing potential of the microbiome changes over the course of colon tumor development or whether receptor subunit expression patterns are altered in colon cancer. Therefore, we investigated the clusters of orthologous group frequencies of glutamate decarboxylase (GAD) in feces from two murine models of colon cancer and found that the frequency of microbial GAD was significantly decreased early in the tumorigenic process. We also determined that microbial-derived GABA inhibited proliferation of colon cancer cells in vitro and that this effect of GABA on SW480 cells involved both GABAA and GABAB receptors. GABA also inhibited prostaglandin E2 (PGE2)-induced proliferation and interleukin-6 (IL-6) expression in these cells. Gene expression correlations were assessed using the "Cancer Exploration" suite of the TIMER2.0 web tool and identified that GABA receptor subunits were differentially expressed in human colon cancer. Moreover, GABAA receptor subunits were predominantly positively associated with PGE2 synthase, cyclooxygenase-2 and IL-6. Collectively, these data demonstrate decreased potential of the microbiome to produce GABA during tumorigenesis, a novel anti-tumorigenic pathway for GABA, and that GABA receptor subunit expression adds a further layer of complexity to GABAergic signaling in colon cancer.
Assuntos
Proliferação de Células , Neoplasias do Colo , Microbioma Gastrointestinal , Receptores de GABA-A , Receptores de GABA-B , Transdução de Sinais , Ácido gama-Aminobutírico , Animais , Neoplasias do Colo/metabolismo , Neoplasias do Colo/microbiologia , Neoplasias do Colo/patologia , Ácido gama-Aminobutírico/metabolismo , Humanos , Camundongos , Linhagem Celular Tumoral , Receptores de GABA-A/metabolismo , Receptores de GABA-A/genética , Receptores de GABA-B/metabolismo , Dinoprostona/metabolismo , Glutamato Descarboxilase/metabolismo , Interleucina-6/metabolismo , Ciclo-Oxigenase 2/metabolismo , Ciclo-Oxigenase 2/genética , Carcinogênese , Fezes/microbiologia , Receptores de GABA/metabolismo , Receptores de GABA/genética , Masculino , Camundongos Endogâmicos C57BL , FemininoRESUMO
The intricate process of neuronal differentiation integrates multiple signals to induce transcriptional, morphological, and electrophysiological changes that reshape the properties of neural precursor cells during their maturation and migration process. An increasing number of neurotransmitters and biomolecules have been identified as molecular signals that trigger and guide this process. In this sense, taurine, a sulfur-containing, non-essential amino acid widely expressed in the mammal brain, modulates the neuronal differentiation process. In this study, we describe the effect of taurine acting via the ionotropic GABAA receptor and the metabotropic GABAB receptor on the neuronal differentiation and electrophysiological properties of precursor cells derived from the subventricular zone of the mouse brain. Taurine stimulates the number of neurites and favors the dendritic complexity of the neural precursor cells, accompanied by changes in the somatic input resistance and the strength of inward and outward membranal currents. At the pharmacological level, the blockade of GABAA receptors inhibits these effects, whereas the stimulation of GABAB receptors has no positive effects on the taurine-mediated differentiation process. Strikingly, the blockade of the GABAB receptor with CGP533737 stimulates neurite outgrowth, dendritic complexity, and membranal current kinetics of neural precursor cells. The effects of taurine on the differentiation process involve Ca2+ mobilization and the activation of intracellular signaling cascades since chelation of intracellular calcium with BAPTA-AM, and inhibition of the CaMKII, ERK1/2, and Src kinase inhibits the neurite outgrowth of neural precursor cells of the subventricular zone.
Assuntos
Diferenciação Celular , Ventrículos Laterais , Células-Tronco Neurais , Receptores de GABA-A , Receptores de GABA-B , Animais , Células-Tronco Neurais/metabolismo , Células-Tronco Neurais/citologia , Células-Tronco Neurais/efeitos dos fármacos , Receptores de GABA-B/metabolismo , Camundongos , Diferenciação Celular/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Ventrículos Laterais/citologia , Ventrículos Laterais/metabolismo , Taurina/farmacologia , Neurogênese/efeitos dos fármacos , Cálcio/metabolismoRESUMO
GABAB receptors (GBRs), the G protein-coupled receptors for GABA, regulate synaptic transmission throughout the brain. A main synaptic function of GBRs is the gating of Cav2.2-type Ca2+ channels. However, the cellular compartment where stable GBR/Cav2.2 signaling complexes form remains unknown. In this study, we demonstrate that the vesicular protein synaptotagmin-11 (Syt11) binds to both the auxiliary GBR subunit KCTD16 and Cav2.2 channels. Through these dual interactions, Syt11 recruits GBRs and Cav2.2 channels to post-Golgi vesicles, thus facilitating assembly of GBR/Cav2.2 signaling complexes. In addition, Syt11 stabilizes GBRs and Cav2.2 channels at the neuronal plasma membrane by inhibiting constitutive internalization. Neurons of Syt11 knockout mice exhibit deficits in presynaptic GBRs and Cav2.2 channels, reduced neurotransmitter release, and decreased GBR-mediated presynaptic inhibition, highlighting the critical role of Syt11 in the assembly and stable expression of GBR/Cav2.2 complexes. These findings support that Syt11 acts as a vesicular scaffold protein, aiding in the assembly of signaling complexes from low-abundance components within transport vesicles. This mechanism enables insertion of pre-assembled functional signaling units into the synaptic membrane.
Assuntos
Camundongos Knockout , Transdução de Sinais , Sinaptotagminas , Animais , Sinaptotagminas/metabolismo , Sinaptotagminas/genética , Camundongos , Humanos , Neurônios/metabolismo , Transmissão Sináptica , Receptores de GABA-B/metabolismo , Receptores de GABA-B/genética , Terminações Pré-Sinápticas/metabolismo , Canais de Cálcio Tipo N/metabolismo , Canais de Cálcio Tipo N/genética , Complexo de Golgi/metabolismo , Ligação Proteica , Células HEK293RESUMO
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
BACKGROUND AND OBJECTIVES: While patients with paraneoplastic autoimmune encephalitis (AE) with gamma-aminobutyric-acid B receptor antibodies (GABABR-AE) have poor functional outcomes and high mortality, the prognosis of nonparaneoplastic cases has not been well studied. METHODS: Patients with GABABR-AE from the French and the Dutch Paraneoplastic Neurologic Syndromes Reference Centers databases were retrospectively included and their data collected; the neurologic outcomes of paraneoplastic and nonparaneoplastic cases were compared. Immunoglobulin G (IgG) isotyping and human leukocyte antigen (HLA) genotyping were performed in patients with available samples. RESULTS: A total of 111 patients (44/111 [40%] women) were enrolled, including 84 of 111 (76%) paraneoplastic and 18 of 111 (16%) nonparaneoplastic cases (cancer status was undetermined for 9 patients). Patients presented with seizures (88/111 [79%]), cognitive impairment (54/111 [49%]), and/or behavioral disorders (34/111 [31%]), and 54 of 111 (50%) were admitted in intensive care unit (ICU). Nonparaneoplastic patients were significantly younger (median age 54 years [range 19-88] vs 67 years [range 50-85] for paraneoplastic cases, p < 0.001) and showed a different demographic distribution. Nonparaneoplastic patients more often had CSF pleocytosis (17/17 [100%] vs 58/78 [74%], p = 0.02), were almost never associated with KTCD16-abs (1/16 [6%] vs 61/70 [87%], p < 0.001), and were more frequently treated with second-line immunotherapy (11/18 [61%] vs 18/82 [22%], p = 0.003). However, no difference of IgG subclass or HLA association was observed, although sample size was small (10 and 26 patients, respectively). After treatment, neurologic outcome was favorable (mRS ≤2) for 13 of 16 (81%) nonparaneoplastic and 37 of 84 (48%) paraneoplastic cases (p = 0.03), while 3 of 18 (17%) and 42 of 83 (51%) patients had died at last follow-up (p = 0.008), respectively. Neurologic outcome no longer differed after adjustment for confounding factors but seemed to be negatively associated with increased age and ICU admission. A better survival was associated with nonparaneoplastic cases, a younger age, and the use of immunosuppressive drugs. DISCUSSION: Nonparaneoplastic GABABR-AE involved younger patients without associated KCTD16-abs and carried better neurologic and vital prognoses than paraneoplastic GABABR-AE, which might be due to a more intensive treatment strategy. A better understanding of immunologic mechanisms underlying both forms is needed.
Assuntos
Autoanticorpos , Encefalite , Doença de Hashimoto , Síndromes Paraneoplásicas do Sistema Nervoso , Receptores de GABA-B , Humanos , Feminino , Masculino , Pessoa de Meia-Idade , Adulto , Idoso , Receptores de GABA-B/imunologia , Encefalite/imunologia , Doença de Hashimoto/imunologia , Autoanticorpos/líquido cefalorraquidiano , Autoanticorpos/sangue , Estudos Retrospectivos , Adulto Jovem , Síndromes Paraneoplásicas do Sistema Nervoso/imunologia , Idoso de 80 Anos ou maisRESUMO
BACKGROUND: Positive allosteric modulators (PAMs) of the GABAB receptor constitute a new class of GABAB-receptor ligands. GABAB PAMs reproduce several pharmacological effects of the orthosteric GABAB receptor agonist, baclofen, although displaying a better safety profile. AIMS: This paper reviews the reducing or, frequently, even suppressing effects of all GABAB PAMs tested to date on multiple alcohol-related behaviours in laboratory rodents exposed to validated experimental models of human alcohol use disorder. RESULTS: Acute or repeated treatment with CGP7930, GS39783, BHF177, rac-BHFF, ADX71441, CMPPE, COR659, ASP8062, KK-92A, and ORM-27669 reduced excessive alcohol drinking, relapse- and binge-like drinking, operant alcohol self-administration, reinstatement of alcohol seeking, and alcohol-induced conditioned place preference in rats and mice. CONCLUSIONS: These effects closely mirrored those of baclofen; notably, they were associated to remarkably lower levels of tolerance and toxicity. The recent transition of ASP8062 to clinical testing will soon prove whether these highly consistent preclinical data translate to AUD patients.
Assuntos
Alcoolismo , Animais , Camundongos , Ratos , Consumo de Bebidas Alcoólicas/tratamento farmacológico , Alcoolismo/tratamento farmacológico , Baclofeno/farmacologia , Baclofeno/uso terapêutico , Agonistas dos Receptores de GABA-B/farmacologia , Agonistas dos Receptores de GABA-B/uso terapêutico , Receptores de GABA-BRESUMO
GABA (γ-amino butyric acid) analogues like baclofen, tolibut, phenibut, etc., are well-known GABAB1 inhibitors and pharmaceutically important drugs. However, there is a huge demand for more chiral GABA aryl analogues with promising pharmacological actions. Here, we demonstrate the chiral ligand acetyl-protected amino quinoline (APAQ) mediated enantioselective synthesis of GABAB1 inhibitor drug scaffolds from easily accessible GABA via Pd-catalyzed C(sp3)-H activation. The synthetic methodology shows moderate to good yields, up to 74% of ee. We have successfully demonstrated the deprotection and removal of the directing group to synthesize R-tolibut in 86% yield. Further, we employed computation to probe the binding of R-GABA analogues to the extracellular domain of the human GABAB1 receptor. Our Rosetta-based molecular docking calculations show better binding for four R-enantiomers of GABA analogues than R-baclofen and R-phenibut. In addition, we employed GROMACS MD simulations and MMPB(GB)SA calculations to identify per-residue contribution to binding free energy. Our computational results suggest analogues (3R)-4-amino-3-(3,4-dimethylphenyl) butanoic acid, (3R)-4-amino-3-(3-fluorophenyl) butanoic acid, (3R)-3-(4-acetylphenyl)-4-aminobutanoic acid, (3R)-4-amino-3-(4-methoxyphenyl) butanoic acid, and (3R)-4-amino-3-phenylbutanoic acid are potential leads which could be synthesized from our methodology reported here.
Assuntos
Simulação de Acoplamento Molecular , Paládio , Receptores de GABA-B , Ácido gama-Aminobutírico , Estereoisomerismo , Paládio/química , Receptores de GABA-B/química , Receptores de GABA-B/metabolismo , Catálise , Humanos , Ácido gama-Aminobutírico/química , Ácido gama-Aminobutírico/síntese química , Ácido gama-Aminobutírico/metabolismo , Estrutura MolecularRESUMO
The balance of activity between glutamatergic and GABAergic networks is particularly important for oscillatory neural activities in the brain. Here, we investigated the roles of GABAB receptors in network oscillation in the oral somatosensory cortex (OSC), focusing on NMDA receptors. Neural oscillation at the frequency of 8-10 Hz was elicited in rat brain slices after caffeine application. Oscillations comprised a non-NMDA receptor-dependent initial phase and a later NMDA receptor-dependent oscillatory phase, with the oscillator located in the upper layer of the OSC. Baclofen was applied to investigate the actions of GABAB receptors. The later NMDA receptor-dependent oscillatory phase completely disappeared, but the initial phase did not. These results suggest that GABAB receptors mainly act on NMDA receptor, in which metabotropic actions of GABAB receptors may contribute to the attenuation of NMDA receptor activities. A regulatory system for network oscillation involving GABAB receptors may be present in the OSC.
Assuntos
Receptores de GABA-B , Receptores de N-Metil-D-Aspartato , Ratos , Animais , Receptores de N-Metil-D-Aspartato/metabolismo , Receptores de GABA-B/metabolismo , Córtex Somatossensorial/metabolismo , BaclofenoRESUMO
Alzheimer's disease (AD) is the most common cause of dementia in the elderly. Recent evidence suggests that gamma-aminobutyric acid B (GABAB) receptor-mediated inhibition is a major contributor to AD pathobiology, and GABAB receptors have been hypothesized to be a potential target for AD treatment. The aim of this study is to determine how GABAB regulation alters cognitive function and brain activity in an AD mouse model. Early, middle and late stage (8-23 months) amyloid precursor protein (APP) and presenilin 1 (PS1) transgenic mice were used for the study. The GABAB agonist baclofen (1 and 2.5 mg/kg, i. p.) and the antagonist phaclofen (0.5 mg/kg, i. p.) were used. Primarily, we found that GABAB activation was able to improve spatial and/or working memory performance in early and late stage AD animals. In addition, GABAB activation and inhibition could regulate global and local EEG oscillations in AD animals, with activation mainly regulating low-frequency activity (delta-theta bands) and inhibition mainly regulating mid- and high-frequency activity (alpha-gamma bands), although the regulated magnitude at some frequencies was reduced in AD. The cognitive improvements in AD animals may be explained by the reduced EEG activity in the theta frequency band (2-4 Hz). This study provides evidence for a potential therapeutic effect of baclofen in the elderly AD brain and for GABAB receptor-mediated inhibition as a potential therapeutic target for AD.
Assuntos
Doença de Alzheimer , Precursor de Proteína beta-Amiloide , Humanos , Camundongos , Animais , Idoso , Precursor de Proteína beta-Amiloide/genética , Precursor de Proteína beta-Amiloide/metabolismo , Camundongos Transgênicos , Baclofeno/farmacologia , Presenilina-1/genética , Receptores de GABA-B , Doença de Alzheimer/tratamento farmacológico , Doença de Alzheimer/metabolismo , Ácido gama-Aminobutírico , Cognição , Eletroencefalografia , Modelos Animais de DoençasRESUMO
The Nociceptin/Orphanin FQ (N/OFQ) peptide and its receptor NOP are highly expressed within several regions of the mesolimbic system, including the ventral tegmental area (VTA). Evidence indicates that the N/OFQ-NOP receptor system is involved in reward processing and historically it has been proposed that activation of NOP receptors attenuates the motivation for substances of abuse. However, recent findings demonstrated that drug self-administration and relapse to drug-seeking are also attenuated after administration of NOP receptor antagonists. Here, to shed light on the mechanisms through which NOP receptor blockers modulate these processes, we utilized ex vivo patch-clamp recordings to investigate the effect of the selective NOP receptor antagonist LY2817412 on VTA dopaminergic (DA) function in male rats. Results showed that, similar to the endogenous NOP receptor agonist N/OFQ, LY2817412 reduced the spontaneous basal firing discharge of VTA DA neurons. Consistently, we found that NOP receptors are expressed both in VTA DA and GABA cells and that LY2817412 slice perfusion increased GABA release onto VTA DA cells. Finally, in the attempt to dissect the role of postsynaptic and presynaptic NOP receptors, we tested the effect of N/OFQ and LY2817412 in the presence of GABA receptors blockers. Results showed that the effect of LY2817412 was abolished following pretreatment with GABABR, but not GABAAR, blockers. Conversely, inhibition of DA neuronal activity by N/OFQ was unaffected by blockade of GABA receptors. Altogether, these results suggest that both NOP receptor agonists and antagonists can decrease VTA DA neuronal activity, but through distinct mechanisms of action. The effect of NOP receptor antagonists occurs through a GABABR-mediated mechanism while NOP receptor agonists seem to act via a direct effect on VTA DA neurons.
Assuntos
Dopamina , Receptores Opioides , Ratos , Masculino , Animais , Receptores Opioides/metabolismo , Área Tegmentar Ventral/metabolismo , Receptor de Nociceptina , Receptores de GABA-B , Nociceptina , Neurônios Dopaminérgicos/metabolismo , Ácido gama-Aminobutírico , Peptídeos Opioides/farmacologiaRESUMO
PURPOSE: Anti-gamma-aminobutyric acid B receptor (GABABR) encephalitis is an uncommon form of autoimmune encephalitis associated with a poor prognosis and a high fatality rate. We aim to find diagnostic markers for anti- GABABR encephalitis as well as the effects of immune cell infiltration on this pathology. METHODS: For quantitative proteomic analysis, isobaric tags for relative and absolute quantitation were used in conjunction with LC-MS/MS analysis. To conduct functional correlation analyses, differentially expressed proteins (DEPs) were identified. Following that, we used bioinformatics analysis to screen for and determine the diagnostic signatures of anti- GABABR encephalitis. ROC curves were used to evaluate the diagnostic values. To assess the inflammatory status of anti- GABABR encephalitis, we used cell-type identification by estimating relative subsets of the RNA transcript (CIBERSORT) and explored the link between diagnostic markers and infiltrating immune cells. RESULTS: Overall, 108 robust DEPs (47 upregulated and 61 downregulated) were identified, of which 11 were immune related. The most impressively enriched pathways were complemented and coagulation cascades, actin cytoskeleton regulation, and cholesterol metabolism; GSEA revealed that the enriched pathways were considerably differentially connected to immune modulation. Eleven immune-related DEPs were chosen for further investigation. We developed a novel diagnostic model based on CSF1R and AZGP1 serum levels using ROC analysis (area under the ROC curve = 1). M1 macrophages and activated natural killer cells are likely to play a role in course of anti- GABABR encephalitis. CONCLUSION: We identified CSF1R and AZGP1 are possible anti-GABABR encephalitis diagnostic indicators, and immune cell infiltration may have a significant impact on the development and occurrence of anti- GABABR encephalitis.
Assuntos
Encefalite , Ácido gama-Aminobutírico , Humanos , Autoanticorpos , Cromatografia Líquida , Proteômica , Receptores de GABA-B , Espectrometria de Massas em TandemRESUMO
GABAB receptor (GBR) activation inhibits neurotransmitter release in axon terminals in the brain, except in medial habenula (MHb) terminals, which show robust potentiation. However, mechanisms underlying this enigmatic potentiation remain elusive. Here, we report that GBR activation on MHb terminals induces an activity-dependent transition from a facilitating, tonic to a depressing, phasic neurotransmitter release mode. This transition is accompanied by a 4.1-fold increase in readily releasable vesicle pool (RRP) size and a 3.5-fold increase of docked synaptic vesicles (SVs) at the presynaptic active zone (AZ). Strikingly, the depressing phasic release exhibits looser coupling distance than the tonic release. Furthermore, the tonic and phasic release are selectively affected by deletion of synaptoporin (SPO) and Ca2+-dependent activator protein for secretion 2 (CAPS2), respectively. SPO modulates augmentation, the short-term plasticity associated with tonic release, and CAPS2 retains the increased RRP for initial responses in phasic response trains. The cytosolic protein CAPS2 showed a SV-associated distribution similar to the vesicular transmembrane protein SPO, and they were colocalized in the same terminals. We developed the "Flash and Freeze-fracture" method, and revealed the release of SPO-associated vesicles in both tonic and phasic modes and activity-dependent recruitment of CAPS2 to the AZ during phasic release, which lasted several minutes. Overall, these results indicate that GBR activation translocates CAPS2 to the AZ along with the fusion of CAPS2-associated SVs, contributing to persistency of the RRP increase. Thus, we identified structural and molecular mechanisms underlying tonic and phasic neurotransmitter release and their transition by GBR activation in MHb terminals.
Assuntos
Habenula , Receptores de GABA-B , Animais , Receptores de GABA-B/genética , Receptores de GABA-B/metabolismo , Habenula/metabolismo , Astacoidea/metabolismo , Terminações Pré-Sinápticas/metabolismo , Cafeína , Neurotransmissores/metabolismo , Ácido gama-Aminobutírico/metabolismoRESUMO
Pain severely affects the physical and mental health of patients. The need to develop nonopioid analgesic drugs to meet medical demands is urgent. In this study, we designed a truncated analogue of αO-conotoxin, named GeX-2, based on disulfide-bond deletion and sequence truncation. GeX-2 retained the potency of its parent peptide at the human α9α10 nAChR and exhibited potent inhibitory activity at CaV2.2 channels via activation of the GABAB receptor (GABABR). Importantly, GeX-2 significantly alleviated pain in the rat model of chronic constriction injury. The dual inhibition of GeX-2 at both α9α10 nAChRs and CaV2.2 channels is speculated to synergistically mediate the potent analgesic effects. Results from site-directed mutagenesis assay and computational modeling suggest that GeX-2 preferentially interacts with the α10(+)α10(-) binding site of α9α10 nAChR and favorably binds to the top region of the GABABR2 subunit. The study offers vital insights into the molecular action mechanism of GeX-2, demonstrating its potential as a novel nonopioid analgesic.
Assuntos
Analgésicos não Narcóticos , Conotoxinas , Receptores Nicotínicos , Ratos , Humanos , Animais , Conotoxinas/química , Receptores de GABA-B/metabolismo , Analgésicos/farmacologia , Analgésicos/uso terapêutico , Analgésicos/química , Dor/tratamento farmacológico , Receptores Nicotínicos/metabolismo , Ácido gama-Aminobutírico , Antagonistas Nicotínicos/farmacologia , Antagonistas Nicotínicos/químicaRESUMO
Network dynamics are crucial for action and sensation. Changes in synaptic physiology lead to the reorganization of local microcircuits. Consequently, the functional state of the network impacts the output signal depending on the firing patterns of its units. Networks exhibit steady states in which neurons show various activities, producing many networks with diverse properties. Transitions between network states determine the output signal generated and its functional results. The temporal dynamics of excitation/inhibition allow a shift between states in an operational network. Therefore, a process capable of modulating the dynamics of excitation/inhibition may be functionally important. This process is known as disinhibition. In this review, we describe the effect of GABA levels and GABAB receptors on tonic inhibition, which causes changes (due to disinhibition) in network dynamics, leading to synchronous functional oscillations.