Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.874
Filtrar
1.
PLoS One ; 15(3): e0230327, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32150746

RESUMO

Sodium Calcium exchanger (NCX) proteins utilize the electrochemical gradient of Na+ to generate Ca2+ efflux (forward mode) or influx (reverse mode). In mammals, there are three unique NCX encoding genes-NCX1, NCX2, and NCX3, that comprise the SLC8A family, and mRNA from all three exchangers is expressed in hippocampal pyramidal cells. Furthermore, mutant ncx2-/- and ncx3-/- mice have each been shown to exhibit altered long-term potentiation (LTP) in the hippocampal CA1 region due to delayed Ca2+ clearance after depolarization that alters synaptic transmission. In addition to the role of NCX at the synapse of hippocampal subfields required for LTP, the three NCX isoforms have also been shown to localize to the dendrite of hippocampal pyramidal cells. In the case of NCX1, it has been shown to localize throughout the basal and apical dendrite of CA1 neurons where it helps compartmentalize Ca2+ between dendritic shafts and spines. Given the role for NCX and calcium in synaptic plasticity, the capacity of NCX splice-forms to influence backpropagating action potentials has clear consequences for the induction of spike-timing dependent synaptic plasticity (STDP). To explore this, we examined the effect of NCX localization, density, and allosteric activation on forward and back propagating signals and, next employed a STDP paradigm to monitor the effect of NCX on plasticity using back propagating action potentials paired with EPSPs. From our simulation studies we identified a role for the sodium calcium exchange current in normalizing STDP, and demonstrate that NCX is required at the postsynaptic site for this response. We also screened other mechanisms in our model and identified a role for the Ca2+ activated K+ current at the postsynapse in producing STDP responses. Together, our data reveal opposing roles for the Na+/Ca2+ exchanger current and the Ca2+ activated K+ current in setting STDP.


Assuntos
Região CA1 Hipocampal/fisiologia , Modelos Neurológicos , Plasticidade Neuronal/fisiologia , Células Piramidais/metabolismo , Trocador de Sódio e Cálcio/metabolismo , Potenciais de Ação/fisiologia , Animais , Região CA1 Hipocampal/citologia , Cálcio/metabolismo , Cátions Bivalentes/metabolismo , Cátions Monovalentes/metabolismo , Simulação por Computador , Modelos Animais , Potássio/metabolismo , Ratos , Sódio/metabolismo
2.
Nat Commun ; 11(1): 1017, 2020 02 24.
Artigo em Inglês | MEDLINE | ID: mdl-32094367

RESUMO

Individuals with autism spectrum disorder (ASD) have social interaction deficits and difficulty filtering information. Inhibitory interneurons filter information at pyramidal neurons of the anterior cingulate cortex (ACC), an integration hub for higher-order thalamic inputs important for social interaction. Humans with deletions including LMO4, an endogenous inhibitor of PTP1B, display intellectual disabilities and occasionally autism. PV-Lmo4KO mice ablate Lmo4 in PV interneurons and display ASD-like repetitive behaviors and social interaction deficits. Surprisingly, increased PV neuron-mediated peri-somatic feedforward inhibition to the pyramidal neurons causes a compensatory reduction in (somatostatin neuron-mediated) dendritic inhibition. These homeostatic changes increase filtering of mediodorsal-thalamocortical inputs but reduce filtering of cortico-cortical inputs and narrow the range of stimuli ACC pyramidal neurons can distinguish. Simultaneous ablation of PTP1B in PV-Lmo4KO neurons prevents these deficits, indicating that PTP1B activation in PV interneurons contributes to ASD-like characteristics and homeostatic maladaptation of inhibitory circuits may contribute to deficient information filtering in ASD.


Assuntos
Transtorno do Espectro Autista/fisiopatologia , Giro do Cíngulo/fisiopatologia , Rede Nervosa/metabolismo , Parvalbuminas/metabolismo , Proteína Tirosina Fosfatase não Receptora Tipo 1/metabolismo , Potenciais de Ação/fisiologia , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Transtorno do Espectro Autista/genética , Transtorno do Espectro Autista/patologia , Técnicas de Observação do Comportamento , Comportamento Animal/fisiologia , Dendritos/fisiologia , Modelos Animais de Doenças , Potenciais Evocados/fisiologia , Feminino , Giro do Cíngulo/citologia , Giro do Cíngulo/patologia , Humanos , Interneurônios/metabolismo , Proteínas com Domínio LIM/genética , Proteínas com Domínio LIM/metabolismo , Masculino , Camundongos , Camundongos Knockout , Inibição Neural/fisiologia , Proteína Tirosina Fosfatase não Receptora Tipo 1/genética , Células Piramidais/metabolismo , Somatostatina/metabolismo , Técnicas Estereotáxicas , Tálamo/citologia , Tálamo/metabolismo
3.
Proc Natl Acad Sci U S A ; 117(6): 3239-3247, 2020 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-31992641

RESUMO

The olfactory system receives extensive serotonergic inputs from the dorsal raphe, a nucleus involved in control of behavior, regulation of mood, and modulation of sensory processing. Although many studies have investigated how serotonin modulates the olfactory bulb, few have focused on the anterior piriform cortex (aPC), a region important for olfactory learning and encoding of odor identity and intensity. Specifically, the mechanism and functional significance of serotonergic modulation of the aPC remain largely unknown. Here we used pharmacologic, optogenetic, and fiber photometry techniques to examine the serotonergic modulation of neural activity in the aPC in vitro and in vivo. We found that serotonin (5-HT) reduces the excitability of pyramidal neurons directly via 5-HT2C receptors, phospholipase C, and calcium-activated potassium (BK) channels. Furthermore, endogenous serotonin attenuates odor-evoked calcium responses in aPC pyramidal neurons. These findings identify the mechanism underlying serotonergic modulation of the aPC and shed light on its potential role.


Assuntos
Núcleo Dorsal da Rafe/metabolismo , Córtex Piriforme , Células Piramidais/metabolismo , Neurônios Serotoninérgicos/metabolismo , Serotonina/metabolismo , Animais , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Odorantes , Bulbo Olfatório/fisiologia , Optogenética , Córtex Piriforme/citologia , Córtex Piriforme/metabolismo , Serotonina/genética
4.
Sci Rep ; 10(1): 1333, 2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-31992779

RESUMO

Inhibitory interneurons derived from the medial ganglionic eminence represent the largest cohort of GABAergic neurons in the hippocampus. In the CA1 hippocampus excitatory synapses onto these cells comprise GluA2-lacking, calcium-permeable AMPARs. Although synaptic transmission is not established until early in their postnatal life, AMPARs are expressed early in development, however their role is enigmatic. Using the Nkx2.1-cre mouse line we genetically deleted GluA1, GluA2, GluA3 selectively from MGE derived interneurons early in development. We observed that the number of MGE-derived interneurons was preserved in mature hippocampus despite early elimination of AMPARs, which resulted in >90% decrease in spontaneous excitatory synaptic activity. Of particular interest, excitatory synaptic sites were shifted from dendritic to somatic locations while maintaining a normal NMDAR content. The developmental switch of NMDARs from GluN2B-containing early in development to GluN2A-containing on maturation was similarly unperturbed despite the loss of AMPARs. Early network giant depolarizing potential oscillatory activity was compromised in early postnatal days as was both feedforward and feedback inhibition onto pyramidal neurons underscoring the importance of glutamatergic drive onto MGE-derived interneurons for hippocampal circuit function.


Assuntos
Potenciais Pós-Sinápticos Excitadores , Deleção de Genes , Interneurônios/metabolismo , Células-Tronco Neurais/citologia , Neurogênese , Células Piramidais/metabolismo , Receptores de AMPA/deficiência , Animais , Região CA1 Hipocampal/citologia , Região CA1 Hipocampal/metabolismo , Cálcio/metabolismo , Diferenciação Celular , Interneurônios/citologia , Canais Iônicos/metabolismo , Camundongos , Camundongos Transgênicos , Células Piramidais/citologia , Receptores de AMPA/metabolismo
5.
Neuron ; 105(1): 75-92.e5, 2020 01 08.
Artigo em Inglês | MEDLINE | ID: mdl-31780329

RESUMO

During neonatal development, sensory cortices generate spontaneous activity patterns shaped by both sensory experience and intrinsic influences. How these patterns contribute to the assembly of neuronal circuits is not clearly understood. Using longitudinal in vivo calcium imaging in un-anesthetized mouse pups, we show that spatially segregated functional assemblies composed of interneurons and pyramidal cells are prominent in the somatosensory cortex by postnatal day (P) 7. Both reduction of GABA release and synaptic inputs onto pyramidal cells erode the emergence of functional topography, leading to increased network synchrony. This aberrant pattern effectively blocks interneuron apoptosis, causing increased survival of parvalbumin and somatostatin interneurons. Furthermore, the effect of GABA on apoptosis is mediated by inputs from medial ganglionic eminence (MGE)-derived but not caudal ganglionic eminence (CGE)-derived interneurons. These findings indicate that immature MGE interneurons are fundamental for shaping GABA-driven activity patterns that balance the number of interneurons integrating into maturing cortical networks.


Assuntos
Neurônios GABAérgicos/fisiologia , Interneurônios/fisiologia , Córtex Somatossensorial/fisiologia , Animais , Apoptose/fisiologia , Sobrevivência Celular/fisiologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Feminino , Neurônios GABAérgicos/metabolismo , Potenciais Pós-Sinápticos Inibidores/fisiologia , Interneurônios/metabolismo , Masculino , Eminência Mediana/fisiologia , Potenciais da Membrana/fisiologia , Camundongos , Camundongos Transgênicos , Vias Neurais/fisiologia , Neurogênese/fisiologia , Parvalbuminas/metabolismo , Células Piramidais/metabolismo , Células Piramidais/fisiologia , Córtex Somatossensorial/crescimento & desenvolvimento , Somatostatina/metabolismo , Potenciais Sinápticos/fisiologia , Ácido gama-Aminobutírico/metabolismo
6.
Nat Methods ; 17(1): 101-106, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31740815

RESUMO

Understanding the function of a tissue requires knowing the spatial organization of its constituent cell types. In the cerebral cortex, single-cell RNA sequencing (scRNA-seq) has revealed the genome-wide expression patterns that define its many, closely related neuronal types, but cannot reveal their spatial arrangement. Here we introduce probabilistic cell typing by in situ sequencing (pciSeq), an approach that leverages previous scRNA-seq classification to identify cell types using multiplexed in situ RNA detection. We applied this method by mapping the inhibitory neurons of mouse hippocampal area CA1, for which ground truth is available from extensive previous work identifying their laminar organization. Our method identified these neuronal classes in a spatial arrangement matching ground truth, and further identified multiple classes of isocortical pyramidal cell in a pattern matching their known organization. This method will allow identifying the spatial organization of closely related cell types across the brain and other tissues.


Assuntos
Região CA1 Hipocampal/citologia , Perfilação da Expressão Gênica/métodos , Neocórtex/citologia , Neurônios/citologia , Células Piramidais/citologia , Análise de Sequência de RNA/métodos , Análise de Célula Única/métodos , Algoritmos , Animais , Região CA1 Hipocampal/metabolismo , Masculino , Camundongos , Modelos Estatísticos , Neocórtex/metabolismo , Neurônios/metabolismo , Células Piramidais/metabolismo
7.
Elife ; 82019 12 20.
Artigo em Inglês | MEDLINE | ID: mdl-31860442

RESUMO

Loss of the RNA binding protein FMRP causes Fragile X Syndrome (FXS), the most common cause of inherited intellectual disability, yet it is unknown how FMRP function varies across brain regions and cell types and how this contributes to disease pathophysiology. Here we use conditional tagging of FMRP and CLIP (FMRP cTag CLIP) to examine FMRP mRNA targets in hippocampal CA1 pyramidal neurons, a critical cell type for learning and memory relevant to FXS phenotypes. Integrating these data with analysis of ribosome-bound transcripts in these neurons revealed CA1-enriched binding of autism-relevant mRNAs, and CA1-specific regulation of transcripts encoding circadian proteins. This contrasted with different targets in cerebellar granule neurons, and was consistent with circadian defects in hippocampus-dependent memory in Fmr1 knockout mice. These findings demonstrate differential FMRP-dependent regulation of mRNAs across neuronal cell types that may contribute to phenotypes such as memory defects and sleep disturbance associated with FXS.


Assuntos
Transtorno Autístico/metabolismo , Região CA1 Hipocampal/metabolismo , Proteína do X Frágil de Retardo Mental/genética , Síndrome do Cromossomo X Frágil/genética , Transtornos da Memória/genética , Células Piramidais/metabolismo , Animais , Transtorno Autístico/genética , Transtorno Autístico/fisiopatologia , Região CA1 Hipocampal/citologia , Cerebelo/citologia , Cerebelo/metabolismo , Relógios Circadianos/genética , Relógios Circadianos/fisiologia , Modelos Animais de Doenças , Proteína do X Frágil de Retardo Mental/metabolismo , Síndrome do Cromossomo X Frágil/metabolismo , Síndrome do Cromossomo X Frágil/fisiopatologia , Regulação da Expressão Gênica , Humanos , Transtornos da Memória/metabolismo , Transtornos da Memória/fisiopatologia , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neurônios/metabolismo
8.
Elife ; 82019 12 27.
Artigo em Inglês | MEDLINE | ID: mdl-31880536

RESUMO

Active dendrites impact sensory processing and behaviour. However, it remains unclear how active dendritic integration relates to somatic output in vivo. We imaged semi-simultaneously GCaMP6s signals in the soma, trunk and distal tuft dendrites of layer 5 pyramidal neurons in the awake mouse primary visual cortex. We found that apical tuft signals were dominated by widespread, highly correlated calcium transients throughout the tuft. While these signals were highly coupled to trunk and somatic transients, the frequency of calcium transients was found to decrease in a distance-dependent manner from soma to tuft. Ex vivo recordings suggest that low-frequency back-propagating action potentials underlie the distance-dependent loss of signals, while coupled somato-dendritic signals can be triggered by high-frequency somatic bursts or strong apical tuft depolarization. Visual stimulation and locomotion increased neuronal activity without affecting somato-dendritic coupling. High, asymmetric somato-dendritic coupling is therefore a widespread feature of layer 5 neurons activity in vivo.


Assuntos
Locomoção/fisiologia , Células Piramidais/fisiologia , Sinapses/fisiologia , Córtex Visual/fisiologia , Potenciais de Ação/fisiologia , Animais , Cálcio/metabolismo , Dendritos/fisiologia , Camundongos , Estimulação Luminosa , Células Piramidais/metabolismo
9.
Elife ; 82019 11 18.
Artigo em Inglês | MEDLINE | ID: mdl-31736463

RESUMO

Optogenetics allows manipulations of genetically and spatially defined neuronal populations with excellent temporal control. However, neurons are coupled with other neurons over multiple length scales, and the effects of localized manipulations thus spread beyond the targeted neurons. We benchmarked several optogenetic methods to inactivate small regions of neocortex. Optogenetic excitation of GABAergic neurons produced more effective inactivation than light-gated ion pumps. Transgenic mice expressing the light-dependent chloride channel GtACR1 produced the most potent inactivation. Generally, inactivation spread substantially beyond the photostimulation light, caused by strong coupling between cortical neurons. Over some range of light intensity, optogenetic excitation of inhibitory neurons reduced activity in these neurons, together with pyramidal neurons, a signature of inhibition-stabilized neural networks ('paradoxical effect'). The offset of optogenetic inactivation was followed by rebound excitation in a light dose-dependent manner, limiting temporal resolution. Our data offer guidance for the design of in vivo optogenetics experiments.


Assuntos
Neurônios GABAérgicos/efeitos da radiação , Transdução de Sinal Luminoso/genética , Neocórtex/efeitos da radiação , Rede Nervosa/efeitos da radiação , Células Piramidais/efeitos da radiação , Córtex Somatossensorial/efeitos da radiação , Animais , Benchmarking , Neurônios GABAérgicos/citologia , Neurônios GABAérgicos/metabolismo , Expressão Gênica , Genes Reporter , Luz , Camundongos , Camundongos Transgênicos , Neocórtex/citologia , Neocórtex/metabolismo , Rede Nervosa/citologia , Rede Nervosa/metabolismo , Optogenética/métodos , Estimulação Luminosa , Células Piramidais/citologia , Células Piramidais/metabolismo , Rodopsina/genética , Rodopsina/metabolismo , Córtex Somatossensorial/citologia , Córtex Somatossensorial/metabolismo , Análise Espaço-Temporal , Transgenes
10.
Nat Commun ; 10(1): 5055, 2019 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-31699994

RESUMO

Rewards influence plasticity of early sensory representations, but the underlying changes in circuitry are unclear. Recent experimental findings suggest that inhibitory circuits regulate learning. In addition, inhibitory neurons are highly modulated by diverse long-range inputs, including reward signals. We, therefore, hypothesise that inhibitory plasticity plays a major role in adjusting stimulus representations. We investigate how top-down modulation by rewards interacts with local plasticity to induce long-lasting changes in circuitry. Using a computational model of layer 2/3 primary visual cortex, we demonstrate how interneuron circuits can store information about rewarded stimuli to instruct long-term changes in excitatory connectivity in the absence of further reward. In our model, stimulus-tuned somatostatin-positive interneurons develop strong connections to parvalbumin-positive interneurons during reward such that they selectively disinhibit the pyramidal layer henceforth. This triggers excitatory plasticity, leading to increased stimulus representation. We make specific testable predictions and show that this two-stage model allows for translation invariance of the learned representation.


Assuntos
Interneurônios/metabolismo , Inibição Neural/fisiologia , Plasticidade Neuronal/fisiologia , Recompensa , Córtex Visual/metabolismo , Animais , Simulação por Computador , Modelos Neurológicos , Vias Neurais/metabolismo , Células Piramidais/metabolismo
11.
PLoS Biol ; 17(10): e3000461, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-31600191

RESUMO

Dendritic spine development is crucial for the establishment of excitatory synaptic connectivity and functional neural circuits. Alterations in spine morphology and density have been associated with multiple neurological disorders. Autism candidate gene disconnected-interacting protein homolog 2 A (DIP2A) is known to be involved in acetylated coenzyme A (Ac-CoA) synthesis and is primarily expressed in the brain regions with abundant pyramidal neurons. However, the role of DIP2A in the brain remains largely unknown. In this study, we found that deletion of Dip2a in mice induced defects in spine morphogenesis along with thin postsynaptic density (PSD), and reduced synaptic transmission of pyramidal neurons. We further identified that DIP2A interacted with cortactin, an activity-dependent spine remodeling protein. The binding activity of DIP2A-PXXP motifs (P, proline; X, any residue) with the cortactin-Src homology 3 (SH3) domain was critical for maintaining the level of acetylated cortactin. Furthermore, Dip2a knockout (KO) mice exhibited autism-like behaviors, including excessive repetitive behaviors and defects in social novelty. Importantly, acetylation mimetic cortactin restored the impaired synaptic transmission and ameliorated repetitive behaviors in these mice. Altogether, our findings establish an initial link between DIP2A gene variations in autism spectrum disorder (ASD) and highlight the contribution of synaptic protein acetylation to synaptic processing.


Assuntos
Acetilcoenzima A/genética , Transtorno do Espectro Autista/genética , Cortactina/genética , Espinhas Dendríticas/metabolismo , Morfogênese/genética , Proteínas Nucleares/genética , Processamento de Proteína Pós-Traducional , Acetilcoenzima A/deficiência , Acetilação , Motivos de Aminoácidos , Animais , Animais Recém-Nascidos , Transtorno do Espectro Autista/metabolismo , Transtorno do Espectro Autista/fisiopatologia , Sítios de Ligação , Cortactina/metabolismo , Espinhas Dendríticas/ultraestrutura , Modelos Animais de Doenças , Embrião de Mamíferos , Regulação da Expressão Gênica no Desenvolvimento , Teste de Complementação Genética , Camundongos , Camundongos Knockout , Proteínas Nucleares/deficiência , Densidade Pós-Sináptica/metabolismo , Densidade Pós-Sináptica/ultraestrutura , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Células Piramidais/metabolismo , Células Piramidais/ultraestrutura , Transmissão Sináptica
12.
PLoS One ; 14(10): e0223469, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31618234

RESUMO

The goal of this study was to investigate the effects of acute cocaine injection or dopamine (DA) receptor antagonists on the medial prefrontal cortex (mPFC) gamma oscillations and their relationship to short term neuroadaptation that may mediate addiction. For this purpose, optogenetically evoked local field potentials (LFPs) in response to a brief 10 ms laser light pulse were recorded from 17 mice. D1-like receptor antagonist SCH 23390 or D2-like receptor antagonist sulpiride, or both, were administered either before or after cocaine. A Euclidian distance-based dendrogram classifier separated the 100 trials for each animal in disjoint clusters. When baseline and DA receptor antagonists trials were combined in a single trial, a minimum of 20% overlap occurred in some dendrogram clusters, which suggests a possible common, invariant, dynamic mechanism shared by both baseline and DA receptor antagonists data. The delay-embedding method of neural activity reconstruction was performed using the correlation time and mutual information to determine the lag/correlation time of LFPs and false nearest neighbors to determine the embedding dimension. We found that DA receptor antagonists applied before cocaine cancels out the effect of cocaine and leaves the lag time distributions at baseline values. On the other hand, cocaine applied after DA receptor antagonists shifts the lag time distributions to longer durations, i.e. increase the correlation time of LFPs. Fourier analysis showed that a reasonable accurate decomposition of the LFP data can be obtained with a relatively small (less than ten) Fourier coefficients.


Assuntos
Antagonistas de Dopamina/farmacologia , Potenciais Evocados , Optogenética , Algoritmos , Animais , Análise por Conglomerados , Potenciais Evocados/efeitos dos fármacos , Análise de Fourier , Interneurônios/efeitos dos fármacos , Interneurônios/metabolismo , Camundongos , Optogenética/métodos , Córtex Pré-Frontal/efeitos dos fármacos , Córtex Pré-Frontal/metabolismo , Células Piramidais/efeitos dos fármacos , Células Piramidais/metabolismo
13.
Proc Natl Acad Sci U S A ; 116(42): 21176-21184, 2019 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-31575739

RESUMO

As the inhibitory γ-aminobutyric acid-ergic (GABAergic) transmission has a pivotal role in the central nervous system (CNS) and defective forms of its synapses are associated with serious neurological disorders, numerous versions of caged GABA and, more recently, photoswitchable ligands have been developed to investigate such transmission. While the complementary nature of these probes is evident, the mechanisms by which the GABA receptors can be photocontrolled have not been fully exploited. In fact, the ultimate need for specificity is critical for the proper synaptic exploration. No caged allosteric modulators of the GABAA receptor have been reported so far; to introduce such an investigational approach, we exploited the structural motifs of the benzodiazepinic scaffold to develop a photocaged version of diazepam (CD) that was tested on basolateral amygdala (BLa) pyramidal cells in mouse brain slices. CD is devoid of any intrinsic activity toward the GABAA receptor before irradiation. Importantly, CD is a photoreleasable GABAA receptor-positive allosteric modulator that offers a different probing mechanism compared to caged GABA and photoswitchable ligands. CD potentiates the inhibitory signaling by prolonging the decay time of postsynaptic GABAergic currents upon photoactivation. Additionally, no effect on presynaptic GABA release was recorded. We developed a photochemical technology to individually study the GABAA receptor, which specifically expands the toolbox available to study GABAergic synapses.


Assuntos
Tonsila do Cerebelo/efeitos dos fármacos , Diazepam/farmacologia , Receptores de GABA-A/metabolismo , Sinapses/metabolismo , Tonsila do Cerebelo/metabolismo , Animais , Camundongos , Camundongos Endogâmicos C57BL , Células Piramidais/efeitos dos fármacos , Células Piramidais/metabolismo , Potenciais Sinápticos/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Ácido gama-Aminobutírico/metabolismo
14.
Neuron ; 104(3): 471-487.e12, 2019 11 06.
Artigo em Inglês | MEDLINE | ID: mdl-31606247

RESUMO

SETD1A, a lysine-methyltransferase, is a key schizophrenia susceptibility gene. Mice carrying a heterozygous loss-of-function mutation of the orthologous gene exhibit alterations in axonal branching and cortical synaptic dynamics accompanied by working memory deficits. We show that Setd1a binds both promoters and enhancers with a striking overlap between Setd1a and Mef2 on enhancers. Setd1a targets are highly expressed in pyramidal neurons and display a complex pattern of transcriptional up- and downregulations shaped by presumed opposing functions of Setd1a on promoters and Mef2-bound enhancers. Notably, evolutionarily conserved Setd1a targets are associated with neuropsychiatric genetic risk burden. Reinstating Setd1a expression in adulthood rescues cognitive deficits. Finally, we identify LSD1 as a major counteracting demethylase for Setd1a and show that its pharmacological antagonism results in a full rescue of the behavioral and morphological deficits in Setd1a-deficient mice. Our findings advance understanding of how SETD1A mutations predispose to schizophrenia (SCZ) and point to novel therapeutic interventions.


Assuntos
Córtex Cerebral/metabolismo , Disfunção Cognitiva/genética , Histona Desmetilases/metabolismo , Histona-Lisina N-Metiltransferase/genética , Memória de Curto Prazo , Esquizofrenia/genética , Psicologia do Esquizofrênico , Animais , Axônios/patologia , Encéfalo/metabolismo , Córtex Cerebral/patologia , Elementos Facilitadores Genéticos , Predisposição Genética para Doença , Histona Desmetilases/antagonistas & inibidores , Mutação com Perda de Função , Fatores de Transcrição MEF2/genética , Camundongos , Neocórtex/metabolismo , Neurônios/metabolismo , Fenótipo , Córtex Pré-Frontal/metabolismo , Regiões Promotoras Genéticas , Células Piramidais/metabolismo , Sinapses/patologia
15.
eNeuro ; 6(5)2019.
Artigo em Inglês | MEDLINE | ID: mdl-31551250

RESUMO

Presynaptic Ca2+ evokes exocytosis, endocytosis, and synaptic plasticity. However, Ca2+ flux and interactions at presynaptic molecular targets are difficult to quantify because fluorescence imaging has limited resolution. In rats of either sex, we measured single varicosity presynaptic Ca2+ using Ca2+ dyes as buffers, and constructed models of Ca2+ dispersal. Action potentials evoked Ca2+ transients with little variation when measured with low-affinity dye (peak amplitude 789 ± 39 nM, within 2 ms of stimulation; decay times, 119 ± 10 ms). Endogenous Ca2+ buffering capacity, action potential-evoked free [Ca2+]i, and total Ca2+ amounts entering terminals were determined using Ca2+ dyes as buffers. These data constrained Monte Carlo (MCell) simulations of Ca2+ entry, buffering, and removal. Simulations of experimentally-determined Ca2+ fluxes, buffered by simulated calbindin28K well fit data, and were consistent with clustered Ca2+ entry followed within 4 ms by diffusion throughout the varicosity. Repetitive stimulation caused free varicosity Ca2+ to sum. However, simulated in nanometer domains, its removal by pumps and buffering was negligible, while local diffusion dominated. Thus, Ca2+ within tens of nanometers of entry, did not accumulate. A model of synaptotagmin1 (syt1)-Ca2+ binding indicates that even with 10 µM free varicosity evoked Ca2+, syt1 must be within tens of nanometers of channels to ensure occupation of all its Ca2+-binding sites. Repetitive stimulation, evoking short-term synaptic enhancement, does not modify probabilities of Ca2+ fully occupying syt1's C2 domains, suggesting that enhancement is not mediated by Ca2+-syt1 interactions. We conclude that at spatiotemporal scales of fusion machines, Ca2+ necessary for their activation is diffusion dominated.


Assuntos
Potenciais de Ação/fisiologia , Sinalização do Cálcio/fisiologia , Cálcio/metabolismo , Terminações Pré-Sinápticas/metabolismo , Células Piramidais/metabolismo , Animais , Região CA1 Hipocampal/metabolismo , Feminino , Masculino , Ratos , Ratos Sprague-Dawley
16.
Mol Med Rep ; 20(3): 2675-2684, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31524261

RESUMO

The present study investigated the effects of the ultrasound (US), a noninvasive technique, on ischemia­reperfusion injury (IRI) following cardiopulmonary resuscitation (CPR). The animals used in the present study were randomized into five groups (n=8 per group) as follows: i) The CPR group, where the rats underwent 6 min of untreated ventricular fibrillation (VF) followed by CPR and defibrillation; ii) the US group, in which the treatment was identical to the CPR group with the exception that rats were exposed to US treatment 24 h prior to CPR; iii) the MLA group, in which the treatment was identical to the US group with the exception that the α7 nicotinic acetylcholine receptor (α7nAChR) antagonist MLA (4 mg/kg) was administered 30 min prior to US and VF respectively; iv) the GTS group, in which the treatment was identical to the CPR group with the exception that the α7nAChR agonist GTS­21 (4 mg/kg) was injected 30 min prior to VF; and v) the SHAM group, in which the rats were exposed to surgical preparation without CPR and US application. At 1 day prior to CPR, the US treatment was administered to the left kidney by US pulses (contrast general mode with 9 MHz) with a bursting mechanical index of 0.72 for 2 min. Following treatment of the left kidney, the right kidney was exposed to identical US treatment for an additional 2 min. The results demonstrated that US preconditioning decreased the number of defibrillations required and shortened the duration of CPR. US also suppressed tumor necrosis factor­α and interleukin­6 levels following resuscitation (P<0.05), and a significantly longer overall survival time was observed in the US­treated animals (P<0.01). In addition, US attenuated neuronal injury and promoted the expression of α7nAChR in hippocampal neurons (P<0.05). However, the protective effects of US were abolished by MLA and imitated by GTS­21. The results of the present study demonstrated that prior exposure to US may improve animal outcomes following CPR, and the protective effects of US may be dependent on the cholinergic anti­inflammatory pathway (CAP) via α7nAChR.


Assuntos
Reanimação Cardiopulmonar , Neuroimunomodulação , Ultrassonografia , Animais , Biomarcadores , Reanimação Cardiopulmonar/métodos , Citocinas/metabolismo , Parada Cardíaca/diagnóstico por imagem , Parada Cardíaca/etiologia , Parada Cardíaca/mortalidade , Parada Cardíaca/terapia , Masculino , Avaliação de Resultados da Assistência ao Paciente , Células Piramidais/metabolismo , Células Piramidais/efeitos da radiação , Ratos , Taxa de Sobrevida , Ultrassonografia/métodos , Receptor Nicotínico de Acetilcolina alfa7/metabolismo
17.
Neuron ; 103(6): 1086-1095.e5, 2019 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-31488328

RESUMO

Astrocytes are particularly promising candidates for reprogramming into neurons, as they maintain some of the original patterning information from their radial glial ancestors. However, to which extent the position of astrocytes influences the fate of reprogrammed neurons remains unknown. To elucidate this, we performed stab wound injury covering an entire neocortical column, including the gray matter (GM) and white matter (WM), and targeted local reactive astrocytes via injecting FLEx switch (Cre-On) adeno-associated viral (AAV) vectors into mGFAP-Cre mice. Single proneural factors were not sufficient for adequate reprogramming, although their combination with the nuclear receptor-related 1 protein (Nurr1) improved reprogramming efficiency. Nurr1 and Neurogenin 2 (Ngn2) resulted in high-efficiency reprogramming of targeted astrocytes into neurons that develop lamina-specific hallmarks, including the appropriate long-distance axonal projections. Surprisingly, in the WM, we did not observe any reprogrammed neurons, thereby unveiling a crucial role of region- and layer-specific differences in astrocyte reprogramming.


Assuntos
Astrócitos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Técnicas de Reprogramação Celular/métodos , Córtex Cerebral/citologia , Córtex Cerebral/lesões , Proteínas do Tecido Nervoso/genética , Membro 2 do Grupo A da Subfamília 4 de Receptores Nucleares/genética , Células Piramidais/metabolismo , Animais , Astrócitos/citologia , Lesões Encefálicas Traumáticas , Dependovirus , Vetores Genéticos , Gliose , Substância Cinzenta/citologia , Camundongos , Neurônios/citologia , Neurônios/metabolismo , Células Piramidais/citologia , Substância Branca/citologia , Ferimentos Perfurantes
18.
EMBO Rep ; 20(11): e47732, 2019 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-31486213

RESUMO

Crosstalk between the actin and microtubule cytoskeletons underlies cellular morphogenesis. Interactions between actin filaments and microtubules are particularly important for establishing the complex polarized morphology of neurons. Here, we characterized the neuronal function of growth arrest-specific 2-like 1 (Gas2L1), a protein that can directly bind to actin, microtubules and microtubule plus-end-tracking end binding proteins. We found that Gas2L1 promotes axon branching, but restricts axon elongation in cultured rat hippocampal neurons. Using pull-down experiments and in vitro reconstitution assays, in which purified Gas2L1 was combined with actin and dynamic microtubules, we demonstrated that Gas2L1 is autoinhibited. This autoinhibition is relieved by simultaneous binding to actin filaments and microtubules. In neurons, Gas2L1 primarily localizes to the actin cytoskeleton and functions as an actin stabilizer. The microtubule-binding tail region of Gas2L1 directs its actin-stabilizing activity towards the axon. We propose that Gas2L1 acts as an actin regulator, the function of which is spatially modulated by microtubules.


Assuntos
Actinas/metabolismo , Axônios/metabolismo , Proteínas dos Microfilamentos/metabolismo , Microtúbulos/metabolismo , Neurônios/citologia , Neurônios/metabolismo , Animais , Biomarcadores , Células COS , Chlorocebus aethiops , Feminino , Células HEK293 , Hipocampo/metabolismo , Humanos , Masculino , Imagem Molecular , Neuritos/metabolismo , Ligação Proteica , Estabilidade Proteica , Transporte Proteico , Células Piramidais/citologia , Células Piramidais/metabolismo , Ratos
19.
Nutrients ; 11(9)2019 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-31461895

RESUMO

Creatine plays a crucial role in developing the brain, so much that its genetic deficiency results in mental dysfunction and cognitive impairments. Moreover, creatine supplementation is currently under investigation as a preventive measure to protect the fetus against oxidative stress during difficult pregnancies. Although creatine use is considered safe, posing minimal risk to clinical health, we found an alteration in morpho-functional maturation of neurons when male rats were exposed to creatine loads during brain development. In particular, increased excitability and enhanced long-term potentiation (LTP) were observed in the hippocampal pyramidal neurons of weaning pups. Since these effects were observed a long time after creatine treatment had been terminated, long-lasting modifications persisting into adulthood were hypothesized. Such modifications were investigated in the present study using morphological, electrophysiological, and calcium imaging techniques applied to hippocampal Cornu Ammonis 1 (CA1) neurons of adult rats born from dams supplemented with creatine. When compared to age-matched controls, the treated adult offspring were found to retain enhanced neuron excitability and an improved LTP, the best-documented neuronal substrate for memory formation. While translating data from rats to humans does have limitations, our findings suggest that prenatal creatine supplementation could have positive effects on adult cognitive abilities.


Assuntos
Região CA1 Hipocampal/efeitos dos fármacos , Creatina/administração & dosagem , Suplementos Nutricionais , Plasticidade Neuronal/efeitos dos fármacos , Efeitos Tardios da Exposição Pré-Natal , Células Piramidais/efeitos dos fármacos , Fatores Etários , Fenômenos Fisiológicos da Nutrição Animal , Animais , Comportamento Animal/efeitos dos fármacos , Região CA1 Hipocampal/crescimento & desenvolvimento , Região CA1 Hipocampal/metabolismo , Sinalização do Cálcio/efeitos dos fármacos , Cognição/efeitos dos fármacos , Feminino , Masculino , Fenômenos Fisiológicos da Nutrição Materna , Memória/efeitos dos fármacos , Gravidez , Células Piramidais/metabolismo , Ratos Sprague-Dawley , Fatores de Tempo
20.
Neurosci Lett ; 708: 134341, 2019 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-31255727

RESUMO

The medial prefrontal cortex (mPFC) is a key regulator of neurocognition. The glutamatergic pyramidal neurons are the predominant component of neurons in the mPFC. Aging and HIV profoundly alter the structure and function of mPFC pyramidal neurons, including, but are not limited to, dysregulation of NMDA receptors and voltage-gated calcium channels. Here we assessed the impact of aging and in vivo HIV exposure on the functional activity (firing) of mPFC pyramidal neurons mediated by voltage-gated K+ (Kv) channels and inwardly-rectifying K+ (Kir) channels using patch-clamp recording in rat brain slices ex vivo. We found that aging and HIV significantly affect firing in different manners by altering the activity of Kv and likely Kir channels, associated with changes in membrane properties and the mRNA levels of specific Kv channels. Evoked firing was significantly decreased in mPFC neurons of older (12 month, 12 m) rats compared to younger (6/7 week, 6/7wk) rats, regardless of HIV status. In contrast, firing was significantly increased in neurons from Tg rats compared to non-Tg rats, regardless of age. Aging/HIV-induced alterations in firing were mediated by dysfunctional Kv channels and Kir channels, which exhibit significant changes in their activity and/or expression induced by aging and HIV exposure in vivo. Collectively, these novel findings demonstrate that aging is associated with a significant decline of mPFC neuronal activity; while long-term HIV exposure in vivo could drive mPFC neurons from over-activation to loss of firing, which could ultimately exacerbate the decline of mPFC neuronal activity.


Assuntos
Envelhecimento , Infecções por HIV/metabolismo , HIV-1/fisiologia , Canais de Potássio Corretores do Fluxo de Internalização/metabolismo , Canais de Potássio de Abertura Dependente da Tensão da Membrana/metabolismo , Córtex Pré-Frontal/metabolismo , Células Piramidais/metabolismo , Células Piramidais/patologia , Potenciais de Ação , Animais , Infecções por HIV/patologia , Masculino , Córtex Pré-Frontal/patologia , RNA Mensageiro/metabolismo , Ratos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA