RESUMO
AIMS: Synaptic dysfunction in Parkinson's disease is caused by propagation of pathogenic α-synuclein between neurons. Previously, in multiple system atrophy (MSA), pathologically characterised by ectopic deposition of abnormal α-synuclein predominantly in oligodendrocytes, we demonstrated that the occurrence of memory impairment was associated with the number of α-synuclein-positive neuronal cytoplasmic inclusions (NCIs) in the hippocampus. In the present study, we aimed to investigate how abnormal α-synuclein in the hippocampus can lead to memory impairment. METHODS: We performed pathological and biochemical analyses using a mouse model of adult-onset MSA and human cases (MSA, N = 25; Parkinson's disease, N = 3; Alzheimer's disease, N = 2; normal controls, N = 11). In addition, the MSA model mice were examined behaviourally and physiologically. RESULTS: In the MSA model, inducible human α-synuclein was first expressed in oligodendrocytes and subsequently accumulated in the cytoplasm of excitatory hippocampal neurons (NCI-like structures) and their presynaptic nerve terminals with the development of memory impairment. α-Synuclein oligomers increased simultaneously in the hippocampus of the MSA model. Hippocampal dendritic spines also decreased in number, followed by suppression of long-term potentiation. Consistent with these findings obtained in the MSA model, post-mortem analysis of human MSA brain tissues showed that cases of MSA with memory impairment developed more NCIs in excitatory hippocampal neurons along with α-synuclein oligomers than those without. CONCLUSIONS: Our results provide new insights into the role of α-synuclein oligomers as a possible pathological cause of memory impairment in MSA.
Assuntos
Atrofia de Múltiplos Sistemas , Doença de Parkinson , Humanos , Atrofia de Múltiplos Sistemas/patologia , alfa-Sinucleína/metabolismo , Doença de Parkinson/patologia , Corpos de Inclusão/patologia , Neurônios/patologia , Encéfalo/patologiaRESUMO
Temporal specification of the neural progenitors (NPs) producing excitatory glutamatergic neurons is essential for histogenesis of the cerebral cortex. Neuroepithelial cells, the primary NPs, transit to radial glia (RG). To coincide with the transition, NPs start to differentiate into neurons, undergoing a switch from symmetric to asymmetric cell division. After the onset of neurogenesis, NPs produce layer-specific neurons in a defined order with precise timing. Here, we show that GABAA receptors (GABAARs) and taurine are involved in this regulatory mechanism. Foetal exposure to GABAAR-antagonists suppressed the transition to RG, switch to asymmetric division, and differentiation into upper-layer neurons. Foetal exposure to GABAAR-agonists caused the opposite effects. Mammalian foetuses are dependent on taurine derived from the mothers. GABA and taurine function as endogenous ligands for GABAARs. Ca2+ imaging showed that NPs principally responded to taurine but not GABA before E13. The histological phenotypes of the taurine transporter knockout mice resembled those of the mice foetally exposed to GABAAR-antagonists. Foetal exposure to GABAAR-modulators resulted in considerable alterations in offspring behavior like core symptoms of autism. These results show that taurine regulates the temporal specification of NPs and that disrupting the taurine-receptor interaction possibly leads to neurodevelopmental disorders.
Assuntos
Córtex Cerebral/diagnóstico por imagem , Córtex Cerebral/fisiologia , Glutamatos/fisiologia , Células-Tronco Neurais/fisiologia , Receptores de GABA-A/fisiologia , Taurina/fisiologia , Animais , Transtorno do Espectro Autista/genética , Transtorno do Espectro Autista/fisiopatologia , Córtex Cerebral/citologia , Feminino , Feto , Antagonistas GABAérgicos/farmacologia , Moduladores GABAérgicos/farmacologia , Glicoproteínas de Membrana/genética , Proteínas de Membrana Transportadoras/genética , Camundongos , Camundongos Endogâmicos ICR , Camundongos Knockout , Técnicas de Patch-Clamp , Placenta/metabolismo , GravidezRESUMO
PURPOSE: The general anesthetics propofol and etomidate mainly exert their anesthetic actions via GABA A receptor (GABAA-R). The GABAA-R activity is influenced by phospholipase C-related inactive protein type-1 (PRIP-1), which is related to trafficking and subcellular localization of GABAA-R. PRIP-1 deficiency attenuates the behavioral reactions to propofol but not etomidate. However, the effect of these anesthetics and of PRIP-1 deficiency on brain activity of CNS are still unclear. In this study, we examined the effects of propofol and etomidate on the electroencephalogram (EEG). METHODS: The cortical EEG activity was recorded in wild-type (WT) and PRIP-1 knockout (PRIP-1 KO) mice. All recorded EEG data were offline analyzed, and the power spectral density and 95% spectral edge frequency of EEG signals were compared between genotypes before and after injections of anesthetics. RESULTS: PRIP-1 deficiency induced increases in EEG absolute powers, but did not markedly change the relative spectral powers during waking and sleep states in the absence of anesthesia. Propofol administration induced increases in low-frequency relative EEG activity and decreases in SEF95 values in WT but not in PRIP-1 KO mice. Following etomidate injection, low-frequency EEG power was increased in both genotype groups. At high frequency, the relative power in PRIP-1 KO mice was smaller than that in WT mice. CONCLUSIONS: The lack of PRIP-1 disrupted the EEG power distribution, but did not affect the depth of anesthesia after etomidate administration. Our analyses suggest that PRIP-1 is differentially involved in anesthetic EEG activity with the regulation of GABAA-R activity.
Assuntos
Etomidato/administração & dosagem , Peptídeos e Proteínas de Sinalização Intracelular/genética , Propofol/administração & dosagem , Proteínas Adaptadoras de Transdução de Sinal , Anestésicos Gerais/administração & dosagem , Anestésicos Intravenosos/administração & dosagem , Animais , Eletroencefalografia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Receptores de GABA-A/efeitos dos fármacosRESUMO
Background Chronic pain is a persistent unpleasant sensation that produces pathological synaptic plasticity in the central nervous system. Both human imaging study and animal studies consistently demonstrate that the anterior cingulate cortex is a critical cortical area for nociceptive and chronic pain processing. Thus far, the mechanisms of excitatory synaptic transmission and plasticity have been well characterized in the anterior cingulate cortex for various models of chronic pain. By contrast, the potential contribution of inhibitory synaptic transmission in the anterior cingulate cortex, in models of chronic pain, is not fully understood. Methods Chronic inflammation was induced by complete Freund adjuvant into the adult mice left hindpaw. We performed in vitro whole-cell patch-clamp recordings from layer II/III pyramidal neurons in two to three days after the complete Freund adjuvant injection and examined if the model could cause plastic changes, including transient and tonic type A γ-aminobutyric acid (GABAA) receptor-mediated inhibitory synaptic transmission, in the anterior cingulate cortex. We analyzed miniature/spontaneous inhibitory postsynaptic currents, GABAA receptor-mediated tonic currents, and evoked inhibitory postsynaptic currents. Finally, we studied if GABAergic transmission-related proteins in the presynapse and postsynapse of the anterior cingulate cortex were altered. Results The complete Freund adjuvant model reduced the frequency of both miniature and spontaneous inhibitory postsynaptic currents compared with control group. By contrast, the average amplitude of these currents was not changed between two groups. Additionally, the complete Freund adjuvant model did not change GABAA receptor-mediated tonic currents nor the set of evoked inhibitory postsynaptic currents when compared with control group. Importantly, protein expression of vesicular GABA transporter was reduced within the presynpase of the anterior cingulate cortex in complete Freund adjuvant model. In contrast, the complete Freund adjuvant model did not change the protein levels of GABAA receptors subunits such as α1, α5, ß2, γ2, and δ. Conclusion Our results suggest that the induction phase of inflammatory pain involves spontaneous GABAergic plasticity at presynaptic terminals of the anterior cingulate cortex.
Assuntos
Dor Crônica/complicações , Dor Crônica/patologia , Giro do Cíngulo/patologia , Inflamação/etiologia , Plasticidade Neuronal/fisiologia , Limiar da Dor/fisiologia , Ácido gama-Aminobutírico/metabolismo , Anestésicos Locais/farmacologia , Anestésicos Locais/uso terapêutico , Animais , Bicuculina/análogos & derivados , Bicuculina/farmacologia , Dor Crônica/induzido quimicamente , Dor Crônica/tratamento farmacológico , Adjuvante de Freund/toxicidade , Antagonistas de Receptores de GABA-A/farmacologia , Giro do Cíngulo/citologia , Técnicas In Vitro , Inflamação/induzido quimicamente , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Confocal , Estimulação Física/efeitos adversos , Potenciais Sinápticos/efeitos dos fármacos , Potenciais Sinápticos/fisiologia , Tetrodotoxina/farmacologia , Proteínas Vesiculares de Transporte de Aminoácidos Inibidores/metabolismoRESUMO
Background Cholinergic systems regulate the synaptic transmission resulting in the contribution of the nociceptive behaviors. Anterior cingulate cortex is a key cortical area to play roles in nociception and chronic pain. However, the effect of the activation of cholinergic system for nociception is still unknown in the cortical area. Here, we tested whether the activation of cholinergic receptors can regulate nociceptive behaviors in adult rat anterior cingulate cortex by integrative methods including behavior, immunohistochemical, and electrophysiological methods. Results We found that muscarinic M1 receptors were clearly expressed in the anterior cingulate cortex. Using behavioral tests, we identified that microinjection of a selective muscarinic M1 receptors agonist McN-A-343 into the anterior cingulate cortex dose dependently increased the mechanical threshold. In contrast, the local injection of McN-A-343 into the anterior cingulate cortex showed normal motor function. The microinjection of a selective M1 receptors antagonist pirenzepine blocked the McN-A-343-induced antinociceptive effect. Pirenzepine alone into the anterior cingulate cortex decreased the mechanical thresholds. The local injection of the GABAA receptors antagonist bicuculline into the anterior cingulate cortex also inhibited the McN-A-343-induced antinociceptive effect and decreased the mechanical threshold. Finally, we further tested whether the activation of M1 receptors could regulate GABAergic transmission using whole-cell patch-clamp recordings. The activation of M1 receptors enhanced the frequency of spontaneous and miniature inhibitory postsynaptic currents as well as the amplitude of spontaneous inhibitory postsynaptic currents in the anterior cingulate cortex. Conclusions These results suggest that the activation of muscarinic M1 receptors in part increased the mechanical threshold by increasing GABAergic transmitter release and facilitating GABAergic transmission in the anterior cingulate cortex.
Assuntos
Analgésicos/uso terapêutico , Giro do Cíngulo/metabolismo , Hiperalgesia/tratamento farmacológico , Receptor Muscarínico M1/metabolismo , Transmissão Sináptica/fisiologia , Ácido gama-Aminobutírico/metabolismo , Cloreto de (4-(m-Clorofenilcarbamoiloxi)-2-butinil)trimetilamônio/farmacologia , Cloreto de (4-(m-Clorofenilcarbamoiloxi)-2-butinil)trimetilamônio/uso terapêutico , Analgésicos/farmacologia , Animais , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , GABAérgicos/farmacologia , Giro do Cíngulo/efeitos dos fármacos , Potenciais Pós-Sinápticos Inibidores/efeitos dos fármacos , Potenciais Pós-Sinápticos Inibidores/fisiologia , Masculino , Atividade Motora/efeitos dos fármacos , Atividade Motora/fisiologia , Agonistas Muscarínicos/farmacologia , Agonistas Muscarínicos/uso terapêutico , Antagonistas Muscarínicos/farmacologia , Pirenzepina/farmacologia , Ratos , Ratos Wistar , Transmissão Sináptica/efeitos dos fármacos , Ácido gama-Aminobutírico/farmacologiaRESUMO
The GABA type A receptor (GABAA-R) is a major target of intravenous anesthetics. Phospholipase C-related inactive protein type-1 (PRIP-1) is important in GABAA-R phosphorylation and membrane trafficking. In this study, we investigated the role of PRIP-1 in general anesthetic action. The anesthetic effects of propofol, etomidate, and pentobarbital were evaluated in wild-type and PRIP-1 knockout (PRIP-1 KO) mice by measuring the latency and duration of loss of righting reflex (LORR) and loss of tail-pinch withdrawal response (LTWR). The effect of pretreatment with okadaic acid (OA), a protein phosphatase 1/2A inhibitor, on propofol- and etomidate-induced LORR was also examined. PRIP-1 deficiency provided the reduction of LORR and LTWR induced by propofol but not by etomidate or pentobarbital, indicating that PRIP-1 could determine the potency of the anesthetic action of propofol. Pretreatment with OA recovered the anesthetic potency induced by propofol in PRIP-1 KO mice. OA injection enhanced phosphorylation of cortical the GABAA-R ß3 subunit in PRIP-1 KO mice. These results suggest that PRIP-1-mediated GABAA-R ß3 subunit phosphorylation might be involved in the general anesthetic action induced by propofol but not by etomidate or pentobarbital.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/deficiência , Anestésicos Intravenosos/administração & dosagem , Propofol/administração & dosagem , Receptores de GABA-A/metabolismo , Animais , Relação Dose-Resposta a Droga , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/fisiologiaRESUMO
P2X7 receptors (P2X7Rs) are ATP-gated ion channels that display the unusual property of current facilitation during long applications of agonists. Here we show that facilitation disappears in chimeric P2X7Rs containing the C-terminus of the P2X2 receptor (P2X2R), and in a truncated P2X7R missing the cysteine-rich domain of the C-terminus. The chimeric and truncated receptors also show an apparent decreased permeability to N-methyl-d-glucamine(+) (NMDG(+)). The effects of genetic modification of the C-terminus on NMDG(+) permeability were mimicked by preapplication of the HSP90 antagonist geldanamycin to the wild-type receptor. Further, the geldanamycin decreased the shift in the reversal potential of the ATP-gated current measured under bi-ionic NMDG(+)/Na(+) condition without affecting the ability of the long application of agonist to facilitate current amplitude. Taken together, the results suggest that HSP90 may be essential for stabilization and function of P2X7Rs through an action on the cysteine-rich domain of the cytoplasmic the C-terminus.
Assuntos
Citoplasma/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Receptores Purinérgicos P2X7/química , Receptores Purinérgicos P2X7/metabolismo , Trifosfato de Adenosina/farmacologia , Animais , Benzoquinonas/farmacologia , Membrana Celular/efeitos dos fármacos , Membrana Celular/metabolismo , Permeabilidade da Membrana Celular/efeitos dos fármacos , Células HEK293 , Humanos , Ativação do Canal Iônico/efeitos dos fármacos , Lactamas Macrocíclicas/farmacologia , Meglumina/metabolismo , Proteínas Mutantes/metabolismo , Ligação Proteica/efeitos dos fármacos , Domínios Proteicos , Ratos , Proteínas Recombinantes/metabolismo , Relação Estrutura-AtividadeRESUMO
Heterotrimeric G proteins, composed of α, ß, and γ subunits, can transduce a variety of signals from seven-transmembrane-type receptors to intracellular effectors. By whole-exome sequencing and subsequent mutation screening, we identified de novo heterozygous mutations in GNAO1, which encodes a Gαo subunit of heterotrimeric G proteins, in four individuals with epileptic encephalopathy. Two of the affected individuals also showed involuntary movements. Somatic mosaicism (approximately 35% to 50% of cells, distributed across multiple cell types, harbored the mutation) was shown in one individual. By mapping the mutation onto three-dimensional models of the Gα subunit in three different complexed states, we found that the three mutants (c.521A>G [p.Asp174Gly], c.836T>A [p.Ile279Asn], and c.572_592del [p.Thr191_Phe197del]) are predicted to destabilize the Gα subunit fold. A fourth mutant (c.607G>A), in which the Gly203 residue located within the highly conserved switch II region is substituted to Arg, is predicted to impair GTP binding and/or activation of downstream effectors, although the p.Gly203Arg substitution might not interfere with Gα binding to G-protein-coupled receptors. Transient-expression experiments suggested that localization to the plasma membrane was variably impaired in the three putatively destabilized mutants. Electrophysiological analysis showed that Gαo-mediated inhibition of calcium currents by norepinephrine tended to be lower in three of the four Gαo mutants. These data suggest that aberrant Gαo signaling can cause multiple neurodevelopmental phenotypes, including epileptic encephalopathy and involuntary movements.
Assuntos
Epilepsia/genética , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/genética , Predisposição Genética para Doença , Mutação/genética , Sequência de Aminoácidos , Substituição de Aminoácidos/genética , Animais , Cálcio/metabolismo , Criança , Pré-Escolar , Eletroencefalografia , Epilepsia/patologia , Epilepsia/fisiopatologia , Exoma/genética , Feminino , Subunidades alfa Gi-Go de Proteínas de Ligação ao GTP/química , Humanos , Lactente , Imageamento por Ressonância Magnética , Camundongos , Modelos Moleculares , Dados de Sequência Molecular , Proteínas Mutantes/química , Proteínas Mutantes/genética , Proteínas Mutantes/metabolismo , Fenótipo , Transporte Proteico , Análise de Sequência de DNA , Transdução de Sinais/genéticaRESUMO
Abnormal α-synuclein (αSyn), including an oligomeric form of αSyn, accumulates and causes neuronal dysfunction in the brains of patients with multiple system atrophy. Neuroprotective drugs that target abnormal αSyn aggregation have not been developed for the treatment of multiple system atrophy. In addition, treating diseases at an early stage is crucial to halting the progress of neuronal damage in neurodegeneration. In this study, using early-stage multiple system atrophy mouse model and in vitro kinetic analysis, we investigated how intranasal and oral administration of trehalose can improve multiple system atrophy pathology and clinical symptoms. The multiple system atrophy model showed memory impairment at least four weeks after αSyn induction. Behavioural and physiological analyses showed that intranasal and oral administration of trehalose reversed memory impairments to near-normal levels. Notably, trehalose treatment reduced the amount of toxic αSyn and increased the aggregated form of αSyn in the multiple system atrophy model brain. In vitro kinetic analysis confirmed that trehalose accelerated the aggregate formation of αSyn. Based on our findings, we propose a novel strategy whereby accelerated αSyn aggregate formation leads to reduced exposure to toxic αSyn oligomers, particularly during the early phase of disease progression.
RESUMO
The electrophysiological properties and functional role of GABAergic signal transmission from neurons to the gap junction-coupled astrocytic network are still unclear. GABA-induced astrocytic Clâ» flux has been hypothesized to affect the driving force for GABAergic transmission by modulating [Clâ»]o. Thus, revealing the properties of GABA-mediated astrocytic responses will deepen our understanding of GABAergic signal transmission. Here, we analysed the Clâ» dynamics of neurons and astrocytes in CA1 hippocampal GABAergic tripartite synapses, using Clâ» imaging during GABA application, and whole cell recordings from interneuron-astrocyte pairs in the stratum lacunosum-moleculare. Astrocytic [Clâ»]i was adjusted to physiological conditions (40 mm). Although GABA application evoked bidirectional Clâ» flux via GABAA receptors and mouse GABA transporter 4 (mGAT4) in CA1 astrocytes, a train of interneuron firing induced only GABAA receptor-mediated inward currents in an adjacent astrocyte. A GAT1 inhibitor increased the interneuron firing-induced currents and induced bicuculline-insensitive, mGAT4 inhibitor-sensitive currents, suggesting that synaptic spillover of GABA predominantly induced the astrocytic Clâ» efflux because GABAA receptors are localized near the synaptic clefts. This GABA-induced Clâ» efflux was accompanied by Clâ» siphoning via the gap junctions of the astrocytic network because gap junction inhibitors significantly reduced the interneuron firing-induced currents. Thus, Clâ» efflux from astrocytes is homeostatically maintained within astrocytic networks. A gap junction inhibitor enhanced the activity-dependent depolarizing shifts of reversal potential of neuronal IPSCs evoked by repetitive stimulation to GABAergic synapses. These results suggest that Clâ» conductance within the astrocytic network may contribute to maintaining GABAergic synaptic transmission by regulating [Clâ»]o.
Assuntos
Astrócitos/fisiologia , Cloretos/fisiologia , Junções Comunicantes/fisiologia , Receptores de GABA-A/fisiologia , Sinapses/fisiologia , Ácido gama-Aminobutírico/fisiologia , Animais , Região CA1 Hipocampal/citologia , Região CA1 Hipocampal/fisiologia , Técnicas In Vitro , Potenciais Pós-Sinápticos Inibidores , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos TransgênicosRESUMO
GABA inhibits mature neurons and conversely excites immature neurons due to lower K(+)-Cl(-) cotransporter 2 (KCC2) expression. We observed that ectopically expressed KCC2 in embryonic cerebral cortices was not active; however, KCC2 functioned in newborns. In vitro studies revealed that taurine increased KCC2 inactivation in a phosphorylation-dependent manner. When Thr-906 and Thr-1007 residues in KCC2 were substituted with Ala (KCC2T906A/T1007A), KCC2 activity was facilitated, and the inhibitory effect of taurine was not observed. Exogenous taurine activated the with-no-lysine protein kinase 1 (WNK1) and downstream STE20/SPS1-related proline/alanine-rich kinase (SPAK)/oxidative stress response 1 (OSR1), and overexpression of active WNK1 resulted in KCC2 inhibition in the absence of taurine. Phosphorylation of SPAK was consistently higher in embryonic brains compared with that of neonatal brains and down-regulated by a taurine transporter inhibitor in vivo. Furthermore, cerebral radial migration was perturbed by a taurine-insensitive form of KCC2, KCC2T906A/T1007A, which may be regulated by WNK-SPAK/OSR1 signaling. Thus, taurine and WNK-SPAK/OSR1 signaling may contribute to embryonic neuronal Cl(-) homeostasis, which is required for normal brain development.
Assuntos
Córtex Cerebral/embriologia , Embrião de Mamíferos/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neurônios/metabolismo , Transdução de Sinais/efeitos dos fármacos , Simportadores/metabolismo , Taurina/farmacologia , Substituição de Aminoácidos , Animais , Linhagem Celular , Córtex Cerebral/citologia , Embrião de Mamíferos/citologia , Homeostase/efeitos dos fármacos , Homeostase/fisiologia , Antígenos de Histocompatibilidade Menor , Mutação de Sentido Incorreto , Proteínas do Tecido Nervoso/genética , Neurônios/citologia , Fosforilação/efeitos dos fármacos , Fosforilação/fisiologia , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Proteínas Serina-Treonina Quinases/imunologia , Proteínas Serina-Treonina Quinases/metabolismo , Ratos , Ratos Wistar , Transdução de Sinais/fisiologia , Simportadores/genética , Proteína Quinase 1 Deficiente de Lisina WNK , Cotransportadores de K e Cl-RESUMO
A de novo 9q33.3-q34.11 microdeletion involving STXBP1 has been found in one of four individuals (group A) with early-onset West syndrome, severe hypomyelination, poor visual attention, and developmental delay. Although haploinsufficiency of STXBP1 was involved in early infantile epileptic encephalopathy in a previous different cohort study (group B), no mutations of STXBP1 were found in two of the remaining three subjects of group A (one was unavailable). We assumed that another gene within the deletion might contribute to the phenotype of group A. SPTAN1 encoding alpha-II spectrin, which is essential for proper myelination in zebrafish, turned out to be deleted. In two subjects, an in-frame 3 bp deletion and a 6 bp duplication in SPTAN1 were found at the initial nucleation site of the alpha/beta spectrin heterodimer. SPTAN1 was further screened in six unrelated individuals with WS and hypomyelination, but no mutations were found. Recombinant mutant (mut) and wild-type (WT) alpha-II spectrin could assemble heterodimers with beta-II spectrin, but alpha-II (mut)/beta-II spectrin heterodimers were thermolabile compared with the alpha-II (WT)/beta-II heterodimers. Transient expression in mouse cortical neurons revealed aggregation of alpha-II (mut)/beta-II and alpha-II (mut)/beta-III spectrin heterodimers, which was also observed in lymphoblastoid cells from two subjects with in-frame mutations. Clustering of ankyrinG and voltage-gated sodium channels at axon initial segment (AIS) was disturbed in relation to the aggregates, together with an elevated action potential threshold. These findings suggest that pathological aggregation of alpha/beta spectrin heterodimers and abnormal AIS integrity resulting from SPTAN1 mutations were involved in pathogenesis of infantile epilepsy.
Assuntos
Deficiências do Desenvolvimento/genética , Sequência de Aminoácidos , Animais , Encéfalo/metabolismo , Células Cultivadas , Humanos , Lactente , Camundongos , Dados de Sequência Molecular , Bainha de Mielina/metabolismo , Fenótipo , Quadriplegia/genética , Espasmos Infantis/genética , Espectrina/genética , TransfecçãoRESUMO
During brain and spinal cord development, GABA and glycine, the inhibitory neurotransmitters, cause depolarization instead of hyperpolarization in adults. Since glycine and GABAA receptors (GABAARs) are chloride (Cl-) ion channel receptor, the conversion of GABA/glycine actions during development is influenced by changes in the transmembrane Cl- gradient, which is regulated by Cl- transporters, NKCC1 (absorption) and KCC2 (expulsion). In immature neurons, inhibitory neurotransmitters are released in a non-vesicular/non-synaptic manner, transitioning to vesicular/synaptic release as the neuron matures. In other word, in immature neurons, neurotransmitters generally act tonically. Thus, the glycine/GABA system is a developmentally multimodal system that is required for neurogenesis, differentiation, migration, and synaptogenesis. The endogenous agonists for these receptors are not fully understood, we address taurine. In this review, we will discuss about the properties and function of taurine during development of neocortex. Taurine cannot be synthesized by fetuses or neonates, and is transferred from maternal blood through the placenta or maternal milk ingestion. In developing neocortex, taurine level is higher than GABA level, and taurine tonically activates GABAARs to control radial migration as a stop signal. In the marginal zone (MZ) of the developing neocortex, endogenous taurine modulates the spread of excitatory synaptic transmission, activating glycine receptors (GlyRs) as an endogenous agonist. Thus, taurine affects information processing and crucial developmental processes such as axonal growth, cell migration, and lamination in the developing cerebral cortex. Additionally, we also refer to the possible mechanism of taurine-regulating Cl- homeostasis. External taurine is uptake by taurine transporter (TauT) and regulates NKCC1 and KCC2 mediated by intracellular signaling pathway, with-no-lysine kinase 1 (WNK1) and its subsequent kinases STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) and oxidative stress response kinase-1 (OSR1). Through the regulation of NKCC1 and KCC2, mediated by the WNK-SPAK/OSR1 signaling pathway, taurine plays a role in maintaining Cl- homeostasis during normal brain development.
RESUMO
BACKGROUND: l-3,4-dihydroxyphenylalanine (l-dopa) is the most effective drug for Parkinson's disease (PD); however, most PD patients develop motor fluctuations including wearing-off and l-dopa-induced dyskinesia (LID). Amantadine is beneficial for improving the motor symptoms, reducing "off" time, and ameliorating LID, although its long-term efficacy remains unknown. OBJECTIVES: To investigate the effects of amantadine on PD and LID using a rat model with repetitive drug treatment. METHOD: We utilized 6-hydroxydopamine injections to develop a hemiparkinsonian rat model. The rats were assigned to four groups: five rats received l-dopa and benserazide for 31 days, six rats received l-dopa and benserazide plus amantadine for 31 days, five rats received l-dopa and benserazide for 15 days followed by l-dopa and benserazide plus amantadine for 16 days, and five rats received l-dopa and benserazide plus amantadine for 15 days followed by l-dopa and benserazide treatment for 16 days. We evaluated the l-dopa-induced abnormal involuntary movements on treatment days 1, 7, 14, 16, 22, and 29. Subsequently, immunohistochemistry for drebrin was performed. RESULTS: l-dopa-induced abnormal movements were reduced on the first day of amantadine treatment, and these effects disappeared with repetitive treatment. In contrast, the extension of l-dopa "on" time was observed after repetitive amantadine treatment. All groups showed enlarged drebrin immunoreactive dots in the dopamine-denervated striatum, indicating that amantadine did not prevent priming effects of repetitive l-dopa treatment. CONCLUSION: Anti-LID effect of amantadine diminished after repetitive treatment, and the effect of amantadine on wearing-off emerged after repetitive treatment in a hemiparkinsonian rat model. Fluctuations in amantadine effects should be considered when using it in clinical settings.
Assuntos
Discinesia Induzida por Medicamentos , Doença de Parkinson , Ratos , Animais , Doença de Parkinson/tratamento farmacológico , Levodopa/farmacologia , Antiparkinsonianos/uso terapêutico , Benserazida/efeitos adversos , Discinesia Induzida por Medicamentos/tratamento farmacológico , Ratos Sprague-Dawley , Amantadina/farmacologia , Amantadina/uso terapêutico , Oxidopamina , Modelos Animais de DoençasRESUMO
Older adult patients with sepsis frequently experience cognitive impairment. The roles of brain neutrophil gelatinase-associated lipocalin (NGAL) and iron in older sepsis patients remain unknown. We investigated the effects of lipopolysaccharide-induced sepsis on novel object recognition test, NGAL levels, an inflammatory mediator tumor necrosis factor-α (TNFα) levels, and iron ion levels in the hippocampus and cortex of young and aged rats. The effect of an iron chelator deferoxamine pretreatment on aged sepsis rats was also examined. Young sepsis-survivor rats did not show impaired novel object recognition, TNFα responses, or a Fe2+/Fe3+ imbalance. They showed hippocampal and cortical NGAL level elevations. Aged sepsis-survivor rats displayed a decreased object discrimination index, elevation of NGAL levels and Fe2+/Fe3+ ratio, and no TNFα responses. Pretreatment with deferoxamine prevented the reduction in the object recognition of aged sepsis-survivor rats. The elevation in hippocampal and cortical NGAL levels caused by lipopolysaccharide was not influenced by deferoxamine pretreatment. The lipopolysaccharide-induced Fe2+/Fe3+ ratio elevation was blocked by deferoxamine pretreatment. In conclusion, our findings suggest that iron homeostasis in the cortex and hippocampus contributes to the maintenance of object recognition ability in older sepsis survivors.
Assuntos
Comportamento Animal , Encéfalo/enzimologia , Disfunção Cognitiva/enzimologia , Ferro/metabolismo , Lipocalina-2/metabolismo , Reconhecimento Psicológico , Sepse/enzimologia , Fatores Etários , Animais , Comportamento Animal/efeitos dos fármacos , Encéfalo/efeitos dos fármacos , Encéfalo/fisiopatologia , Disfunção Cognitiva/fisiopatologia , Disfunção Cognitiva/prevenção & controle , Disfunção Cognitiva/psicologia , Desferroxamina/farmacologia , Modelos Animais de Doenças , Homeostase , Masculino , Teste de Campo Aberto , Ratos Sprague-Dawley , Reconhecimento Psicológico/efeitos dos fármacos , Sepse/tratamento farmacológico , Sepse/fisiopatologia , Sepse/psicologia , Sideróforos/farmacologia , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Background: Gamma-aminobutyric acid (GABA) type A receptors are positively allosterically modulated by benzodiazepine binding, leading to a potentiated response to GABA. Diazepam (DZP, a benzodiazepine) is widely prescribed for anxiety, epileptic discharge, and insomnia, and is also used as a muscle relaxant and anti-convulsant. However, some adverse effects - such as tolerance, dependence, withdrawal effects, and impairments in cognition and learning - are elicited by the long-term use of DZP. Clinical studies have reported that chronic DZP treatment increases the risk of dementia in older adults. Furthermore, several studies have reported that chronic DZP administration may affect neuronal activity in the hippocampus, dendritic spine structure, and cognitive performance. However, the effects of chronic DZP administration on cognitive function in aged mice is not yet completely understood. Methods: A behavioral test, immunohistochemical analysis of neurogenic and apoptotic markers, dendritic spine density analysis, and long-term potentiation (LTP) assay of the hippocampal CA1 and CA3 were performed in both young (8 weeks old) and middle-aged (12 months old) mice to investigate the effects of chronic DZP administration on cognitive function. The chronic intraperitoneal administration of DZP was performed by implanting an osmotic minipump. To assess spatial learning and memory ability, the Morris water maze test was performed. Dendritic spines were visualized using Lucifer yellow injection into the soma of hippocampal neurons, and spine density was analyzed. Moreover, the effects of exercise on DZP-induced changes in spine density and LTP in the hippocampus were assessed. Results: Learning performance was impaired by chronic DZP administration in middle-aged mice but not in young mice. LTP was attenuated by DZP administration in the CA1 of young mice and the CA3 of middle-aged mice. The spine density of hippocampal neurons was decreased by chronic DZP administration in the CA1 of both young and middle-aged mice as well as in the CA3 of middle-aged mice. Neither neurogenesis nor apoptosis in the hippocampus was affected by chronic DZP administration. Conclusion: The results of this study suggest that the effects of chronic DZP are different between young and middle-aged mice. The chronic DZP-induced memory retrieval performance impairment in middle-aged mice can likely be attributed to decreased LTP and dendritic spine density in hippocampal neurons in the CA3. Notably, prophylactic exercise suppressed the adverse effects of chronic DZP on LTP and spine maintenance in middle-aged mice.
RESUMO
OBJECTIVE: Although autism spectrum disorder (ASD) occurs worldwide, most genomic studies on ASD were performed on those of Western ancestry. We hypothesized ASD-related copy number variations (CNVs) of Japanese individuals might be different from those of Western individuals. METHODS: Subjects were recruited from the Hirosaki 5-year-old children's developmental health check-up (HFC) between 2013 and 2016 (ASD group; n = 68, control group; n = 124). This study conducted CNV analysis using genomic DNA from peripheral blood of 5-year-old Japanese children. Fisher's exact test was applied for profiling subjects and CNV loci. RESULTS: Four ASD-related CNVs: deletion at 12p11.1, duplications at 4q13.2, 8p23.1 and 18q12.3 were detected (P = 0.015, 0.024, 0.009, 0.004, respectively). Specifically, the odds ratio of duplication at 18q12.3 was highest among the 4 CNVs (odds ratio, 8.13). CONCLUSIONS: Four CNVs: microdeletion at 12p11.1, microduplications at 4q13.2, 8p23.1 and 18q12.3 were detected as ASD-related CNVs in Japanese children in this study. Although these CNVs were consistent with several reports by Western countries at cytoband levels, these did not consistent at detailed genomic positions and sizes. Our data indicate the possibility that these CNVs are characteristic of Japanese children with ASD. We conclude that Japanese individuals with ASD may harbor CNVs different from those of Western individuals with ASD.
Assuntos
Transtorno do Espectro Autista/genética , Variações do Número de Cópias de DNA , Predisposição Genética para Doença , Transtorno do Espectro Autista/diagnóstico , Estudos de Casos e Controles , Pré-Escolar , Feminino , Estudo de Associação Genômica Ampla , Humanos , Japão , Masculino , Polimorfismo de Nucleotídeo ÚnicoRESUMO
BACKGROUND: We have recently reported that the spinal angiotensin (Ang) converting enzyme (ACE)/Ang II/AT1 receptor axis and downstream p38 MAPK phosphorylation are activated in streptozotocin (STZ)-induced diabetic mice and lead to tactile hypersensitivity. Moreover, our previous results suggested that the intrathecal (i.t.) administration of Ang (1-7), an N-terminal fragment of Ang II, may attenuate the Ang II-induced nociceptive behaviour through the inhibition of p38 MAPK phosphorylation via Mas receptors. Here, we investigated whether the i.t. administration of Ang (1-7) can attenuate STZ-induced diabetic neuropathic pain. METHODS: Tactile and thermal hypersensitivities were determined using the von Frey filament and Hargreaves tests, respectively. The protein expression of ACE2, Mas receptors and phospho-p38 MAPK was measured by western blotting. Spinal ACE2 activity was determined using ACE2 activity assay kit. RESULTS: The i.t. administration of Ang (1-7) significantly reduced the tactile and thermal hypersensitivities on day 14 after STZ injection, and these effects were significantly prevented by the Mas receptor antagonist A779. The expression of ACE2 and Mas receptors in the plasma membrane fraction of the lumbar dorsal spinal cord was both significantly decreased in STZ mice. Spinal ACE2 activity was also decreased while p38 MAPK phosphorylation was increased in the lumbar dorsal region of these mice. This phosphorylation was attenuated by the injection of Ang (1-7), whose effect was reversed by A779. CONCLUSIONS: Our data demonstrate that Ang (1-7) attenuates STZ-induced diabetic neuropathic pain and that this occurs through a mechanism involving spinal Mas receptors and he inhibition of p38 MAPK phosphorylation. SIGNIFICANCE: The ACE2/Ang (1-7)/Mas receptor axis was down-regulated in the spinal cord of STZ mice and the i.t. administration of Ang (1-7) attenuated the STZ-induced diabetic neuropathic pain via Mas receptors. Therefore, the activation of this axis could be an effective therapeutic target to alleviate the neuropathic pain in diabetic patients.
Assuntos
Angiotensina I/farmacologia , Diabetes Mellitus Experimental/metabolismo , Neuropatias Diabéticas/metabolismo , Hiperestesia/metabolismo , Neuralgia/metabolismo , Percepção da Dor/efeitos dos fármacos , Fragmentos de Peptídeos/farmacologia , Vasodilatadores/farmacologia , Angiotensina II/análogos & derivados , Angiotensina II/farmacologia , Enzima de Conversão de Angiotensina 2 , Animais , Diabetes Mellitus Experimental/complicações , Neuropatias Diabéticas/etiologia , Hiperestesia/etiologia , Masculino , Camundongos , Neuralgia/etiologia , Peptidil Dipeptidase A/efeitos dos fármacos , Peptidil Dipeptidase A/metabolismo , Fosforilação/efeitos dos fármacos , Proto-Oncogene Mas , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Proteínas Proto-Oncogênicas/efeitos dos fármacos , Proteínas Proto-Oncogênicas/metabolismo , Receptores Acoplados a Proteínas G/antagonistas & inibidores , Receptores Acoplados a Proteínas G/efeitos dos fármacos , Receptores Acoplados a Proteínas G/metabolismo , Medula Espinal/efeitos dos fármacos , Medula Espinal/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/efeitos dos fármacos , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
It has been reported that neuroinflammation occurs in the central nervous system (CNS) in patients with neuropathic pain, Alzheimer's disease and autism spectrum disorder. The 18-kDa translocator protein TSPO is used as an imaging target in positron emission tomography to detect neuroinflammation, and its expression is correlated with microglial activation. However, the mechanism underlying the transcriptional regulation of Tspo induced by inflammation is not clear. Here, we revealed that lipopolysaccharide (LPS) -induced Tspo expression was activated by the AP-1 complex in a mouse microglial cell line, BV-2. Knockdown of c-Fos and c-Jun, the components of AP-1, reduced LPS-induced Tspo expression. Furthermore, the enrichment of Sp1 in the proximal promoter region of Tspo was increased in the presence of LPS. In addition, the binding of histone deacetylase 1 (HDAC1) to the enhancer region, which contains the AP-1 site, was decreased by LPS treatment, but there were no significant differences in HDAC1 binding to the proximal promoter region with or without LPS. These results indicated that HDAC1 is involved not in the proximal promoter region but in the enhancer region. Our study revealed that inflammatory signals induce the recruitment of AP-1 to the enhancer region and Sp1 to the proximal promoter region of the Tspo gene and that Sp1 may regulate the basal expression of Tspo.
Assuntos
Regulação da Expressão Gênica/efeitos dos fármacos , Lipopolissacarídeos/farmacologia , Microglia/efeitos dos fármacos , Receptores de GABA/genética , Fator de Transcrição AP-1/genética , Animais , Sítios de Ligação/genética , Linhagem Celular , Elementos Facilitadores Genéticos/genética , Histona Desacetilase 1/metabolismo , Humanos , Camundongos , Microglia/citologia , Microglia/metabolismo , Ligação Proteica , Interferência de RNA , Receptores de GABA/metabolismo , Fator de Transcrição AP-1/metabolismoRESUMO
Major histocompatibility complex class I (MHCI) is an important immune protein that is expressed in various brain regions, with its deficiency leading to extensive synaptic transmission that results in learning and memory deficits. Although MHCI is highly expressed in dopaminergic neurons, its role in these neurons has not been examined. We show that MHCI expressed in dopaminergic neurons plays a key role in suppressing reward-seeking behavior. In wild-type mice, cocaine self-administration caused persistent reduction of MHCI specifically in dopaminergic neurons, which was accompanied by enhanced glutamatergic synaptic transmission and relapse to cocaine seeking. Functional MHCI knockout promoted this addictive phenotype for cocaine and a natural reward, namely, sucrose. In contrast, wild-type mice overexpressing a major MHCI gene (H2D) in dopaminergic neurons showed suppressed cocaine seeking. These results show that persistent cocaine-induced reduction of MHCI in dopaminergic neurons is necessary for relapse to cocaine seeking.