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1.
Immunity ; 57(1): 86-105.e9, 2024 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-38159572

RESUMO

Triggering receptor expressed on myeloid cells 2 (Trem2) is a myeloid cell-specific gene expressed in brain microglia, with variants that are associated with neurodegenerative diseases, including Alzheimer's disease. Trem2 is essential for microglia-mediated synaptic refinement, but whether Trem2 contributes to shaping neuronal development remains unclear. Here, we demonstrate that Trem2 plays a key role in controlling the bioenergetic profile of pyramidal neurons during development. In the absence of Trem2, developing neurons in the hippocampal cornus ammonis (CA)1 but not in CA3 subfield displayed compromised energetic metabolism, accompanied by reduced mitochondrial mass and abnormal organelle ultrastructure. This was paralleled by the transcriptional rearrangement of hippocampal pyramidal neurons at birth, with a pervasive alteration of metabolic, oxidative phosphorylation, and mitochondrial gene signatures, accompanied by a delay in the maturation of CA1 neurons. Our results unveil a role of Trem2 in controlling neuronal development by regulating the metabolic fitness of neurons in a region-specific manner.


Assuntos
Doença de Alzheimer , Microglia , Doença de Alzheimer/genética , Doença de Alzheimer/metabolismo , Encéfalo/metabolismo , Metabolismo Energético , Microglia/metabolismo , Neurônios/metabolismo , Animais , Camundongos
2.
Immunity ; 54(11): 2611-2631.e8, 2021 11 09.
Artigo em Inglês | MEDLINE | ID: mdl-34758338

RESUMO

Early prenatal inflammatory conditions are thought to be a risk factor for different neurodevelopmental disorders. Maternal interleukin-6 (IL-6) elevation during pregnancy causes abnormal behavior in offspring, but whether these defects result from altered synaptic developmental trajectories remains unclear. Here we showed that transient IL-6 elevation via injection into pregnant mice or developing embryos enhanced glutamatergic synapses and led to overall brain hyperconnectivity in offspring into adulthood. IL-6 activated synaptogenesis gene programs in glutamatergic neurons and required the transcription factor STAT3 and expression of the RGS4 gene. The STAT3-RGS4 pathway was also activated in neonatal brains during poly(I:C)-induced maternal immune activation, which mimics viral infection during pregnancy. These findings indicate that IL-6 elevation at early developmental stages is sufficient to exert a long-lasting effect on glutamatergic synaptogenesis and brain connectivity, providing a mechanistic framework for the association between prenatal inflammatory events and brain neurodevelopmental disorders.


Assuntos
Hipocampo/metabolismo , Interleucina-6/biossíntese , Exposição Materna , Neurônios/metabolismo , Efeitos Tardios da Exposição Pré-Natal , Sinapses/metabolismo , Animais , Citocinas/biossíntese , Modelos Animais de Doenças , Suscetibilidade a Doenças , Feminino , Hipocampo/fisiopatologia , Mediadores da Inflamação/metabolismo , Camundongos , Gravidez , Transdução de Sinais , Transmissão Sináptica
3.
Immunity ; 48(5): 979-991.e8, 2018 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-29752066

RESUMO

The triggering receptor expressed on myeloid cells 2 (TREM2) is a microglial innate immune receptor associated with a lethal form of early, progressive dementia, Nasu-Hakola disease, and with an increased risk of Alzheimer's disease. Microglial defects in phagocytosis of toxic aggregates or apoptotic membranes were proposed to be at the origin of the pathological processes in the presence of Trem2 inactivating mutations. Here, we show that TREM2 is essential for microglia-mediated synaptic refinement during the early stages of brain development. The absence of Trem2 resulted in impaired synapse elimination, accompanied by enhanced excitatory neurotransmission and reduced long-range functional connectivity. Trem2-/- mice displayed repetitive behavior and altered sociability. TREM2 protein levels were also negatively correlated with the severity of symptoms in humans affected by autism. These data unveil the role of TREM2 in neuronal circuit sculpting and provide the evidence for the receptor's involvement in neurodevelopmental diseases.


Assuntos
Encéfalo/imunologia , Glicoproteínas de Membrana/imunologia , Microglia/imunologia , Neurônios/imunologia , Receptores Imunológicos/imunologia , Sinapses/imunologia , Animais , Transtorno Autístico/genética , Transtorno Autístico/imunologia , Transtorno Autístico/metabolismo , Encéfalo/citologia , Encéfalo/metabolismo , Células Cultivadas , Humanos , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Camundongos Endogâmicos C57BL , Camundongos Knockout , Microglia/citologia , Microglia/metabolismo , Neurônios/metabolismo , Receptores Imunológicos/genética , Receptores Imunológicos/metabolismo , Sinapses/metabolismo , Transmissão Sináptica/genética , Transmissão Sináptica/imunologia
4.
EMBO J ; 39(16): e105380, 2020 08 17.
Artigo em Inglês | MEDLINE | ID: mdl-32657463

RESUMO

Neuronal circuit assembly requires the fine balance between synapse formation and elimination. Microglia, through the elimination of supernumerary synapses, have an established role in this process. While the microglial receptor TREM2 and the soluble complement proteins C1q and C3 are recognized as key players, the neuronal molecular components that specify synapses to be eliminated are still undefined. Here, we show that exposed phosphatidylserine (PS) represents a neuronal "eat-me" signal involved in microglial-mediated pruning. In hippocampal neuron and microglia co-cultures, synapse elimination can be partially prevented by blocking accessibility of exposed PS using Annexin V or through microglial loss of TREM2. In vivo, PS exposure at both hippocampal and retinogeniculate synapses and engulfment of PS-labeled material by microglia occurs during established developmental periods of microglial-mediated synapse elimination. Mice deficient in C1q, which fail to properly refine retinogeniculate connections, have elevated presynaptic PS exposure and reduced PS engulfment by microglia. These data provide mechanistic insight into microglial-mediated synapse pruning and identify a novel role of developmentally regulated neuronal PS exposure that is common among developing brain structures.


Assuntos
Hipocampo/metabolismo , Microglia/metabolismo , Neurônios/metabolismo , Fosfatidilserinas/metabolismo , Sinapses/metabolismo , Animais , Técnicas de Cocultura , Complemento C1q/genética , Complemento C1q/metabolismo , Complemento C3/genética , Complemento C3/metabolismo , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/metabolismo , Camundongos , Camundongos Knockout , Fosfatidilserinas/genética , Receptores Imunológicos/genética , Receptores Imunológicos/metabolismo , Sinapses/genética
5.
Brain Behav Immun ; 117: 493-509, 2024 03.
Artigo em Inglês | MEDLINE | ID: mdl-38307446

RESUMO

In the last years, the hypothesis that elevated levels of proinflammatory cytokines contribute to the pathogenesis of neurodevelopmental diseases has gained popularity. IL-1 is one of the main cytokines found to be elevated in Autism spectrum disorder (ASD), a complex neurodevelopmental condition characterized by defects in social communication and cognitive impairments. In this study, we demonstrate that mice lacking IL-1 signaling display autistic-like defects associated with an excessive number of synapses. We also show that microglia lacking IL-1 signaling at early neurodevelopmental stages are unable to properly perform the process of synapse engulfment and display excessive activation of mammalian target of rapamycin (mTOR) signaling. Notably, even the acute inhibition of IL-1R1 by IL-1Ra is sufficient to enhance mTOR signaling and reduce synaptosome phagocytosis in WT microglia. Finally, we demonstrate that rapamycin treatment rescues the defects in IL-1R deficient mice. These data unveil an exclusive role of microglial IL-1 in synapse refinement via mTOR signaling and indicate a novel mechanism possibly involved in neurodevelopmental disorders associated with defects in the IL-1 pathway.


Assuntos
Transtorno do Espectro Autista , Transtorno Autístico , Animais , Camundongos , Microglia , Serina-Treonina Quinases TOR , Citocinas , Sirolimo/farmacologia , Sinapses , Interleucina-1 , Mamíferos
6.
EMBO J ; 38(1)2019 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-30396995

RESUMO

Control of synapse number and function in the developing central nervous system is critical to the formation of neural circuits. Astrocytes play a key role in this process by releasing factors that promote the formation of excitatory synapses. Astrocyte-secreted thrombospondins (TSPs) induce the formation of structural synapses, which however remain post-synaptically silent, suggesting that completion of early synaptogenesis may require a two-step mechanism. Here, we show that the humoral innate immune molecule Pentraxin 3 (PTX3) is expressed in the developing rodent brain. PTX3 plays a key role in promoting functionally-active CNS synapses, by increasing the surface levels and synaptic clustering of AMPA glutamate receptors. This process involves tumor necrosis factor-induced protein 6 (TSG6), remodeling of the perineuronal network, and a ß1-integrin/ERK pathway. Furthermore, PTX3 activity is regulated by TSP1, which directly interacts with the N-terminal region of PTX3. These data unveil a fundamental role of PTX3 in promoting the first wave of synaptogenesis, and show that interplay of TSP1 and PTX3 sets the proper balance between synaptic growth and synapse function in the developing brain.


Assuntos
Proteína C-Reativa/fisiologia , Matriz Extracelular/metabolismo , Integrina beta1/metabolismo , Proteínas do Tecido Nervoso/fisiologia , Receptores de AMPA/metabolismo , Sinapses/fisiologia , Animais , Astrócitos/metabolismo , Encéfalo/crescimento & desenvolvimento , Encéfalo/metabolismo , Proteína C-Reativa/genética , Células CHO , Células Cultivadas , Cricetinae , Cricetulus , Matriz Extracelular/genética , Camundongos , Camundongos Endogâmicos C57BL , Proteínas do Tecido Nervoso/genética , Plasticidade Neuronal/genética , Transporte Proteico/genética , Trombospondina 1/metabolismo
8.
PLoS Pathog ; 16(7): e1008654, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32673372

RESUMO

Prion protein (PrP) mutations are linked to genetic prion diseases, a class of phenotypically heterogeneous neurodegenerative disorders with invariably fatal outcome. How mutant PrP triggers neurodegeneration is not known. Synaptic dysfunction precedes neuronal loss but it is not clear whether, and through which mechanisms, disruption of synaptic activity ultimately leads to neuronal death. Here we show that mutant PrP impairs the secretory trafficking of AMPA receptors (AMPARs). Specifically, intracellular retention of the GluA2 subunit results in synaptic exposure of GluA2-lacking, calcium-permeable AMPARs, leading to increased calcium permeability and enhanced sensitivity to excitotoxic cell death. Mutant PrPs linked to different genetic prion diseases affect AMPAR trafficking and function in different ways. Our findings identify AMPARs as pathogenic targets in genetic prion diseases, and support the involvement of excitotoxicity in neurodegeneration. They also suggest a mechanistic explanation for how different mutant PrPs may cause distinct disease phenotypes.


Assuntos
Cálcio/metabolismo , Neurônios/metabolismo , Proteínas PrPSc/metabolismo , Receptores de AMPA/metabolismo , Sinapses/metabolismo , Animais , Morte Celular/fisiologia , Camundongos , Permeabilidade , Transporte Proteico/fisiologia
9.
EMBO J ; 32(12): 1730-44, 2013 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-23685357

RESUMO

Actin-based remodelling underlies spine structural changes occurring during synaptic plasticity, the process that constantly reshapes the circuitry of the adult brain in response to external stimuli, leading to learning and memory formation. A positive correlation exists between spine shape and synaptic strength and, consistently, abnormalities in spine number and morphology have been described in a number of neurological disorders. In the present study, we demonstrate that the actin-regulating protein, Eps8, is recruited to the spine head during chemically induced long-term potentiation in culture and that inhibition of its actin-capping activity impairs spine enlargement and plasticity. Accordingly, mice lacking Eps8 display immature spines, which are unable to undergo potentiation, and are impaired in cognitive functions. Additionally, we found that reduction in the levels of Eps8 occurs in brains of patients affected by autism compared to controls. Our data reveal the key role of Eps8 actin-capping activity in spine morphogenesis and plasticity and indicate that reductions in actin-capping proteins may characterize forms of intellectual disabilities associated with spine defects.


Assuntos
Actinas/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Encéfalo/metabolismo , Espinhas Dendríticas/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Sinapses/metabolismo , Actinas/genética , Proteínas Adaptadoras de Transdução de Sinal/genética , Animais , Transtorno Autístico/genética , Transtorno Autístico/metabolismo , Cognição/fisiologia , Espinhas Dendríticas/genética , Humanos , Potenciação de Longa Duração/fisiologia , Camundongos , Camundongos Knockout , Proteínas do Tecido Nervoso/genética , Sinapses/genética
10.
EMBO Rep ; 14(7): 645-51, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23732542

RESUMO

SNAP-25 is a key component of the synaptic-vesicle fusion machinery, involved in several psychiatric diseases including schizophrenia and ADHD. SNAP-25 protein expression is lower in different brain areas of schizophrenic patients and in ADHD mouse models. How the reduced expression of SNAP-25 alters the properties of synaptic transmission, leading to a pathological phenotype, is unknown. We show that, unexpectedly, halved SNAP-25 levels at 13-14 DIV not only fail to impair synaptic transmission but instead enhance evoked glutamatergic neurotransmission. This effect is possibly dependent on presynaptic voltage-gated calcium channel activity and is not accompanied by changes in spontaneous quantal events or in the pool of readily releasable synaptic vesicles. Notably, synapses of 13-14 DIV neurons with reduced SNAP-25 expression show paired-pulse depression as opposed to paired-pulse facilitation occurring in their wild-type counterparts. This phenotype disappears with synapse maturation. As alterations in short-term plasticity represent a new mechanism contributing to cognitive impairments in intellectual disabilities, our data provide mechanistic clues for neuronal circuit alterations in psychiatric diseases characterized by reduced expression of SNAP-25.


Assuntos
Ácido Glutâmico/metabolismo , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Transmissão Sináptica/fisiologia , Proteína 25 Associada a Sinaptossoma/metabolismo , Potenciais de Ação/efeitos dos fármacos , Potenciais de Ação/fisiologia , Animais , Cálcio/metabolismo , Canais de Cálcio/genética , Canais de Cálcio/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Inativação Gênica , Ácido Glutâmico/farmacologia , Hipocampo/citologia , Hipocampo/efeitos dos fármacos , Humanos , Camundongos , Plasticidade Neuronal/efeitos dos fármacos , Neurônios/citologia , Neurônios/efeitos dos fármacos , Cultura Primária de Células , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Ratos , Transmissão Sináptica/efeitos dos fármacos , Vesículas Sinápticas/efeitos dos fármacos , Vesículas Sinápticas/fisiologia , Proteína 25 Associada a Sinaptossoma/antagonistas & inibidores , Proteína 25 Associada a Sinaptossoma/genética , Ácido gama-Aminobutírico/metabolismo , Ácido gama-Aminobutírico/farmacologia
11.
Anal Chem ; 84(22): 9833-40, 2012 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-23094863

RESUMO

Neuroinflammation plays a central role in neurodegenerative diseases and involves a large number of interactions between different brain cell types. Unraveling the complexity of cell-cell interaction in neuroinflammation is crucial for both clarifying the molecular mechanisms involved and increasing efficacy in drug development. Here, we provide a versatile analytical method for specifically addressing cell-to-cell communication, using primary brain cells, a microfluidic device, and a multiparametric readout approach. Different cell types are plated in separate chambers of a microfluidic network so that culturing conditions can be independently controlled and single cell types can be selectively primed with different stimuli. When chambers are microfluidically connected, the specific contribution of each cell type can be finely monitored by analyzing morphology, vitality, calcium dynamics, and electrophysiology parameters. We exemplify this approach by examining the role of astrocytes derived from two different brain regions (cortex and hippocampus) on neuronal viability in two types of neuroinflammatory insults, namely, metabolic stress and exposure to amyloid ß fibrils, and demonstrate regional differences in glial control of neuronal physiopathology. In particular, we show that during metabolic stress, cortical but not hippocampal astrocytes play a neuroprotective role; also, in an exacerbated inflammatory scenario consisting in the exposure to Aß + IL-1ß, hippocampal but not cortical astrocytes play a detrimental role on neurons. Aside from bringing novel insights into the glial role in neuroinflammation, the method presented here represents a promising tool for addressing a wide range of biological and biochemical phenomena, characterized by a complex interaction of multiple cell types.


Assuntos
Encéfalo/patologia , Comunicação Celular , Técnicas Analíticas Microfluídicas/métodos , Peptídeos beta-Amiloides/química , Peptídeos beta-Amiloides/farmacologia , Animais , Astrócitos/efeitos dos fármacos , Astrócitos/patologia , Isquemia Encefálica/patologia , Comunicação Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/patologia , Hipocampo/patologia , Inflamação/patologia , Neurônios/efeitos dos fármacos , Neurônios/patologia , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/farmacologia , Multimerização Proteica , Estrutura Secundária de Proteína , Ratos
12.
Cereb Cortex ; 20(7): 1539-55, 2010 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-19812239

RESUMO

By regulating the neocortical excitability, nicotinic acetylcholine receptors (nAChRs) control vigilance and cognition and are implicated in epileptogenesis. Modulation of gamma-aminobutyric acid (GABA) release often accompanies these processes. We studied how nAChRs regulate GABAergic transmission in the murine neocortex with immunocytochemical and patch-clamp methods. The cholinergic fibers densely innervated the somatosensory, visual, motor, and prefrontal cortices (PFC). Laminar distribution was broadly homogeneous, especially in the PFC. The cholinergic terminals were often adjacent to the soma and dendrites of GABAergic interneurons, but well-differentiated synapses were rare. Tonically applied nicotine (1-100 microM) increased the frequency of spontaneous GABAergic inhibitory postsynaptic currents (IPSCs) on pyramidal neurons in PFC layer V. The contribution of nAChR types was assessed by using 1 microM dihydro-beta-erythroidine (DHbetaE), to block heteromeric nAChRs, and 10 nM methyllycaconitine (MLA), to block homomeric nAChRs. Both inhibitors antagonized the effect of nicotine on IPSCs, suggesting that mixed nAChR types control pyramidal neuron inhibition in layer V. To determine whether nAChRs are expressed on basket cells' terminals, we studied miniature IPSCs (mIPSCs). These were revealed using 0.5 microM tetrodotoxin and 50 microM Cd(2+) to isolate the GABAergic terminals from the action potential drive. The nicotinic stimulation of mIPSCs was antagonized by DHbetaE, but not MLA, indicating that heteromeric nAChRs prevail in GABAergic terminals. Immunocytochemistry confirmed the expression of nAChRs on basket cells' somata and terminals. Finally, when the ionotropic glutamatergic transmission was blocked, nicotine partially inhibited the IPSCs, an effect counteracted by both DHbetaE and MLA. Therefore, a fraction of nAChRs are capable of activating GABAergic interneurons that in turn inhibit other GABAergic interneurons, thereby reducing the IPSCs. We conclude that heteromeric nAChRs control GABA release presynaptically, whereas mixed nAChRs regulate both excitation and inhibition of interneurons, the balance depending on the overall glutamatergic drive.


Assuntos
Córtex Pré-Frontal/metabolismo , Receptores Nicotínicos/fisiologia , Ácido gama-Aminobutírico/metabolismo , 6-Ciano-7-nitroquinoxalina-2,3-diona/farmacologia , Animais , Animais Recém-Nascidos , Biofísica , Colina O-Acetiltransferase/metabolismo , Estimulação Elétrica , Antagonistas de Aminoácidos Excitatórios/farmacologia , Glutamato Descarboxilase/metabolismo , Técnicas In Vitro , Potenciais Pós-Sinápticos Inibidores/efeitos dos fármacos , Potenciais Pós-Sinápticos Inibidores/fisiologia , Lisina/análogos & derivados , Lisina/metabolismo , Camundongos , Microscopia Confocal/métodos , Microscopia Eletrônica de Transmissão/métodos , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Técnicas de Patch-Clamp/métodos , Córtex Pré-Frontal/citologia , Córtex Pré-Frontal/efeitos dos fármacos , Valina/análogos & derivados , Valina/farmacologia , Proteínas Vesiculares de Transporte de Acetilcolina/metabolismo
13.
Front Immunol ; 12: 640937, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33708226

RESUMO

The role of microglia in controlling synapse homeostasis is becoming increasingly recognized by the scientific community. In particular, the microglia-mediated elimination of supernumerary synapses during development lays the basis for the correct formation of neuronal circuits in adulthood, while the possible reactivation of this process in pathological conditions, such as schizophrenia or Alzheimer's Disease, provides a promising target for future therapeutic strategies. The methodological approaches to investigate microglial synaptic engulfment include different in vitro and in vivo settings. Basic in vitro assays, employing isolated microglia and microbeads, apoptotic membranes, liposomes or synaptosomes allow the quantification of the microglia phagocytic abilities, while co-cultures of microglia and neurons, deriving from either WT or genetically modified mice models, provide a relatively manageable setting to investigate the involvement of specific molecular pathways. Further detailed analysis in mice brain is then mandatory to validate the in vitro assays as representative for the in vivo situation. The present review aims to dissect the main technical approaches to investigate microglia-mediated phagocytosis of neuronal and synaptic substrates in critical developmental time windows.


Assuntos
Microglia , Plasticidade Neuronal , Neurociências/métodos , Sinapses , Animais , Humanos , Neurogênese/fisiologia , Fagocitose/fisiologia
14.
Adv Exp Med Biol ; 674: 95-105, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20549943

RESUMO

Plastic expression of different integrin subunits controls the different stages of neural development, whereas in the adult integrins regulate synaptic stability. Evidence of integrin-channel crosstalk exists for ionotropic glutamate receptors. As is often the case in other tissues, integrin engagement regulates channel activity through complex signaling pathways that often include tyrosine phosphorylation cascades. The specific pathways recruited by integrin activation depend on cerebral region and cell type. In turn, ion channels control integrin expression onto the plasma membrane and their ligand binding affinity. The most extensive studies concern the hippocampus and suggest implications for neuronal circuit plasticity. The physiological relevance of these findings depends on whether adhesion molecules, aside from determining tissue stability, contribute to synaptogenesis and the responsiveness of mature synapses, thus contributing to long-term circuit consolidation. Little evidence is available for other ligand-gated channels, with the exception of nicotinic receptors. These exert a variety of functions in neurons and non neural tissue, both in development and in the adult, by regulating cell cycle, synaptogenesis and synaptic circuit refinement. Detailed studies in epidermal keratinocytes have shed some light on the possible mechanisms through which ACh can regulate cell motility, which may be of general relevance for morphogenetic processes. As to the control of mature synapses, most results concern the integrinic control of nicotinic receptors in the neuromuscular junction. Following this lead, a few studies have addressed similar topics in adult cerebral synapses. However, pursuing and interpreting these results in the brain is especially difficult because of the complexity of the nicotinic roles and the widespread contribution of nonsynaptic, paracrine transmission. From a pathological point of view, considering the well-known contribution of both integrins and ligand-gated channels to synaptogenesis and neural regeneration, the above studies point to interesting implications for epileptogenesis.


Assuntos
Membrana Celular/metabolismo , Integrinas/metabolismo , Ativação do Canal Iônico/fisiologia , Canais Iônicos/metabolismo , Acetilcolina/metabolismo , Animais , Movimento Celular/fisiologia , Córtex Cerebral/embriologia , Córtex Cerebral/metabolismo , Epiderme/metabolismo , Hipocampo/metabolismo , Hipocampo/patologia , Humanos , Queratinócitos/metabolismo , Neurogênese/fisiologia , Junção Neuromuscular/metabolismo , Plasticidade Neuronal/fisiologia , Neurônios/metabolismo , Comunicação Parácrina/fisiologia , Receptores de Glutamato/metabolismo , Receptores Nicotínicos/metabolismo , Regeneração/fisiologia
15.
Neuropsychopharmacology ; 33(6): 1464-75, 2008 May.
Artigo em Inglês | MEDLINE | ID: mdl-17653110

RESUMO

It is well documented that N-methyl-3,4-methylenedioxyamphetamine (MDMA, ecstasy) releases brain serotonin (5-HT; 5-hydroxytryptamine), noradrenaline (NE; norepinephrine), and dopamine, but the consequent effect on brain functioning remains elusive. In this study, we characterized the effects of MDMA on electrically evoked responses in the ventral CA1 region of a rat hippocampal slice preparation. Superfusion with MDMA (10 microM, 30 min) increased the population spike amplitude (PSA) by 48.9+/-31.2% and decreased population spike latency (PSL) by 103+/-139 mus (both: mean+/-SD, n=123; p<0.0001, Wilcoxon test), without affecting field excitatory postsynaptic potential (fEPSP). This effect persisted for at least 1 h after MDMA washout; we have called this EPSP-spike potentiation (ESP) by MDMA, ESP MDMA. Antagonism of GABAergic transmission did not prevent ESP MDMA, suggesting that an increase in excitability of pyramidal cells underlies this MDMA action. Block of serotonin transporter (SERT) with citalopram or 5-HT depletion with (+/-)-p-chlorophenylalanine pretreatment partially inhibited the ESP MDMA. Block of both SERT and NE transporter prevented ESP MDMA, indicating its dependence on release of both 5-HT and NE. ESP MDMA is produced by simultaneous activation of 5-HT4 and beta1 receptors, with a predominant role of 5-HT4 receptors. Block of both 5-HT4 and beta1 receptors revealed an inhibitory component of the MDMA action mediated by 5-HT1A receptor. The concentration range of MDMA which produced ESP MDMA (1-30 microM) corresponds to that commonly reached in human plasma following the ingestion of psychoactive MDMA doses, suggesting that release of both 5-HT and NE, and consequent ESP MDMA may underlie some of the psychoactive effects of MDMA in humans.


Assuntos
Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Hipocampo/efeitos dos fármacos , N-Metil-3,4-Metilenodioxianfetamina/farmacologia , Norepinefrina/metabolismo , Serotoninérgicos/farmacologia , Serotonina/metabolismo , Adrenérgicos/farmacologia , Animais , Relação Dose-Resposta a Droga , Estimulação Elétrica , Potenciais Pós-Sinápticos Excitadores/fisiologia , Potenciais Pós-Sinápticos Excitadores/efeitos da radiação , Técnicas In Vitro , Masculino , Técnicas de Patch-Clamp , Ratos , Ratos Sprague-Dawley , Receptores Adrenérgicos beta/fisiologia , Receptores 5-HT4 de Serotonina/fisiologia , Estatísticas não Paramétricas
16.
Biol Psychiatry ; 83(8): 680-691, 2018 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-29146047

RESUMO

BACKGROUND: The association between maternal infection and neurodevelopmental defects in progeny is well established, although the biological mechanisms and the pathogenic trajectories involved have not been defined. METHODS: Pregnant dams were injected intraperitoneally at gestational day 9 with polyinosinic:polycytidylic acid. Neuronal development was assessed by means of electrophysiological, optical, and biochemical analyses. RESULTS: Prenatal exposure to polyinosinic:polycytidylic acid causes an imbalanced expression of the Na+-K+-2Cl- cotransporter 1 and the K+-Cl- cotransporter 2 (KCC2). This results in delayed gamma-aminobutyric acid switch and higher susceptibility to seizures, which endures up to adulthood. Chromatin immunoprecipitation experiments reveal increased binding of the repressor factor RE1-silencing transcription (also known as neuron-restrictive silencer factor) to position 509 of the KCC2 promoter that leads to downregulation of KCC2 transcription in prenatally exposed offspring. Interleukin-1 receptor type I knockout mice, which display braked immune response and no brain cytokine elevation upon maternal immune activation, do not display KCC2/Na+-K+-2Cl- cotransporter 1 imbalance when implanted in a wild-type dam and prenatally exposed. Notably, pretreatment of pregnant dams with magnesium sulfate is sufficient to prevent the early inflammatory state and the delay in excitatory-to-inhibitory switch associated to maternal immune activation. CONCLUSIONS: We provide evidence that maternal immune activation hits a key neurodevelopmental process, the excitatory-to-inhibitory gamma-aminobutyric acid switch; defects in this switch have been unequivocally linked to diseases such as autism spectrum disorder or epilepsy. These data open the avenue for a safe pharmacological treatment that may prevent the neurodevelopmental defects caused by prenatal immune activation in a specific pregnancy time window.


Assuntos
Córtex Cerebral/fisiologia , Epilepsia/etiologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Potenciais Pós-Sinápticos Inibidores/fisiologia , Complicações na Gravidez/imunologia , Efeitos Tardios da Exposição Pré-Natal/etiologia , Ácido gama-Aminobutírico , Animais , Técnicas de Cultura de Células , Modelos Animais de Doenças , Embrião de Mamíferos , Feminino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Técnicas de Patch-Clamp , Gravidez , Receptores Tipo I de Interleucina-1 , Simportadores , Cotransportadores de K e Cl-
17.
Front Mol Neurosci ; 11: 313, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30233314

RESUMO

Actin-based remodeling underlines spine morphogenesis and plasticity and is crucially involved in the processes that constantly reshape the circuitry of the adult brain in response to external stimuli, leading to learning and memory formation and supporting cognitive functions. Hence spine morphology and synaptic strength are tightly linked and indeed abnormalities in spine number and morphology have been described in a number of neurological disorders such as autism spectrum disorders (ASDs), schizophrenia and intellectual disabilities. We have recently demonstrated that the actin regulating protein, Epidermal growth factor receptor pathway substrate 8 (Eps8), is essential for spine growth and long term potentiation. Indeed, mice lacking Eps8 display immature filopodia-like spines, which are unable to undergo potentiation, and are impaired in cognitive functions. Furthermore, reduced levels of Eps8 have been found in the brain of a cohort of patients affected by ASD compared to controls. Here we investigated whether the lack of Eps8, which is also part of the N-methyl-d-aspartate (NMDA) receptor complex, affects the functional maturation of the postsynaptic compartment. Our results demonstrate that Eps8 knock out mice (Eps8 KO) neurons display altered synaptic expression and subunit composition of NMDA receptors (i.e., increased GluN2B-, decreased GluN2A-containing receptors) and impaired GluN2B to GluN2A subunit shift. Indeed Eps8 KO neurons display increased content of GluN2B containing NMDA receptors both at the synaptic and extrasynaptic level. Furthermore, Eps8 KO neurons display an increased content of extra-synaptic GluN2B-containing receptors, suggesting that also the synaptic targeting of NMDA receptors is affected by the lack of Eps8. These data demonstrate that, besides regulation of spine morphogenesis, Eps8 also regulates the synaptic balance of NMDA receptors subunits GluN2A and GluN2B.

18.
Elife ; 62017 03 28.
Artigo em Inglês | MEDLINE | ID: mdl-28347403

RESUMO

Inflammation modifies risk and/or severity of a variety of brain diseases through still elusive molecular mechanisms. Here we show that hyperactivation of the interleukin 1 pathway, through either ablation of the interleukin 1 receptor 8 (IL-1R8, also known as SIGIRR or Tir8) or activation of IL-1R, leads to up-regulation of the mTOR pathway and increased levels of the epigenetic regulator MeCP2, bringing to disruption of dendritic spine morphology, synaptic plasticity and plasticity-related gene expression. Genetic correction of MeCP2 levels in IL-1R8 KO neurons rescues the synaptic defects. Pharmacological inhibition of IL-1R activation by Anakinra corrects transcriptional changes, restores MeCP2 levels and spine plasticity and ameliorates cognitive defects in IL-1R8 KO mice. By linking for the first time neuronal MeCP2, a key player in brain development, to immune activation and demonstrating that synaptic defects can be pharmacologically reversed, these data open the possibility for novel treatments of neurological diseases through the immune system modulation.


Assuntos
Proteína 2 de Ligação a Metil-CpG/metabolismo , Neurônios/fisiologia , Receptores de Interleucina-1/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Animais , Camundongos , Camundongos Knockout , Receptores de Interleucina-1/deficiência , Receptores de Interleucina-1/genética
19.
Stem Cell Res Ther ; 6: 166, 2015 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-26345473

RESUMO

INTRODUCTION: Tumor necrosis factor alpha (TNFα) plays a physiological role in controlling synaptic transmission and plasticity in the healthy central nervous system by modulating glutamate receptor trafficking to the plasma membrane. TNFα expression is also rapidly induced in response to tissue injury and infection. By promoting the insertion of Ca(2+) permeable-AMPA receptors into the neuronal plasma membrane, this cytokine may cause excessive Ca(2+) influx into neurons, thus enhancing neuronal death. METHODS: Primary cultures of cortical neurons were obtained from E18 foetal mice and incubated for 24 h with adult neural stem cells (aNPCs) either stimulated with lipopolysaccharide (LPS(+)aNPCs) or not (aNPCs). Cultures were treated with TNFα (100 ng/ml), and electrophysiological recordings were performed in different conditions to evaluate the effect of the cytokine on neuronal transmission. RESULTS: In this study, we demonstrate that aNPCs from the subventricular zone reverse the effects induced by the cytokine. Moreover, we show that the effect of aNPCs on cortical neurons is mediated by cannabinoid CB1 receptor activation. CONCLUSION: These data suggest that the role of aNPCs in preventing excitatory neurotransmission potentiation induced by TNFα on cortical neurons may have important implications for pathologies characterized by an inflammatory component affecting cortical neurons such as Alzheimer's disease.


Assuntos
Células-Tronco Neurais/fisiologia , Neurônios/fisiologia , Fator de Necrose Tumoral alfa/farmacologia , Animais , Células Cultivadas , Ventrículos Laterais/citologia , Camundongos , Células-Tronco Neurais/citologia , Células-Tronco Neurais/efeitos dos fármacos , Neurogênese , Neurônios/citologia , Neurônios/efeitos dos fármacos , Transmissão Sináptica
20.
Nanoscale ; 5(22): 10963-74, 2013 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-24065287

RESUMO

Activation of glial cells, including astrocytes and microglia, has been implicated in the inflammatory responses underlying brain injury and neurodegenerative diseases including Alzheimer's and Parkinson's diseases. The classic activation state (M1) is characterized by high capacity to present antigens, high production of nitric oxide (NO) and reactive oxygen species (ROS) and proinflammatory cytokines. Classically activated cells act as potent effectors that drive the inflammatory response and may mediate detrimental effects on neural cells. The second phenotype (M2) is an alternative, apparently beneficial, activation state, more related to a fine tuning of inflammation, scavenging of debris, promotion of angiogenesis, tissue remodeling and repair. Specific environmental chemical signals are able to induce these different polarization states. We provide here evidence that nanostructured substrates are able, exclusively in virtue of their physical properties, to push microglia toward the proinflammatory activation phenotype, with an efficacy which reflects the graded nanoscale rugosity. The acquisition of a proinflammatory phenotype appears specific for microglia and not astrocytes, indicating that these two cell types, although sharing common innate immune responses, respond differently to external physical stimuli.


Assuntos
Astrócitos/efeitos dos fármacos , Nanopartículas Metálicas/toxicidade , Microglia/efeitos dos fármacos , Titânio/química , Animais , Astrócitos/metabolismo , Células Cultivadas , Citocinas/metabolismo , Lipopolissacarídeos/toxicidade , Nanopartículas Metálicas/química , Camundongos , Camundongos Endogâmicos C57BL , Microglia/metabolismo , Óxido Nítrico/metabolismo , Ratos , Ratos Sprague-Dawley , Propriedades de Superfície
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