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1.
PLoS Biol ; 18(8): e3000820, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32866173

RESUMO

Mutations in the gene encoding the microtubule-severing protein spastin (spastic paraplegia 4 [SPG4]) cause hereditary spastic paraplegia (HSP), associated with neurodegeneration, spasticity, and motor impairment. Complicated forms (complicated HSP [cHSP]) further include cognitive deficits and dementia; however, the etiology and dysfunctional mechanisms of cHSP have remained unknown. Here, we report specific working and associative memory deficits upon spastin depletion in mice. Loss of spastin-mediated severing leads to reduced synapse numbers, accompanied by lower miniature excitatory postsynaptic current (mEPSC) frequencies. At the subcellular level, mutant neurons are characterized by longer microtubules with increased tubulin polyglutamylation levels. Notably, these conditions reduce kinesin-microtubule binding, impair the processivity of kinesin family protein (KIF) 5, and reduce the delivery of presynaptic vesicles and postsynaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. Rescue experiments confirm the specificity of these results by showing that wild-type spastin, but not the severing-deficient and disease-associated K388R mutant, normalizes the effects at the synaptic, microtubule, and transport levels. In addition, short hairpin RNA (shRNA)-mediated reduction of tubulin polyglutamylation on spastin knockout background normalizes KIF5 transport deficits and attenuates the loss of excitatory synapses. Our data provide a mechanism that connects spastin dysfunction with the regulation of kinesin-mediated cargo transport, synapse integrity, and cognition.


Assuntos
Ácido Glutâmico/metabolismo , Cinesina/metabolismo , Transtornos da Memória/metabolismo , Transtornos da Memória/fisiopatologia , Memória de Curto Prazo , Neurônios/metabolismo , Espastina/deficiência , Tubulina (Proteína)/metabolismo , Potenciais de Ação , Animais , Membrana Celular/metabolismo , Espinhas Dendríticas/metabolismo , Espinhas Dendríticas/ultraestrutura , Potenciais Pós-Sinápticos Excitadores , Hipocampo/patologia , Hipocampo/fisiopatologia , Camundongos Knockout , Microtúbulos/metabolismo , Microtúbulos/ultraestrutura , Atividade Motora , Neurônios/patologia , Neurônios/ultraestrutura , Transporte Proteico , Espastina/metabolismo , Sinapses/metabolismo , Sinapses/ultraestrutura , Vesículas Sinápticas/metabolismo
2.
J Pharmacol Sci ; 144(2): 76-82, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32736867

RESUMO

Astrocytes, comprising the primary glial-cell type, are involved in the formation and maturation of synapses, and thus contribute to sustainable synaptic transmission between neurons. Given that the animals in higher phylogenetic tree have brains with a higher density of glial cells with respect to neurons, there is a possibility that the relative astrocytic density directly influences synaptic transmission. However, the notion has not been tested thoroughly. Here we addressed it, by using a primary culture preparation where single hippocampal neurons are surrounded by a variable but a countable number of cortical astrocytes in dot-patterned microislands, and recording synaptic transmission by patch-clamp electrophysiology. Neurons with a higher astrocytic density showed a higher amplitude of the evoked excitatory postsynaptic current than that of neurons with a lower astrocytic density. The size of the readily releasable pool of synaptic vesicles per neuron was significantly larger. The frequency of spontaneous synaptic transmission was higher, but the amplitude was unchanged. The number of morphologically identified glutamatergic synapses was comparable, but the percentage of functional ones was increased, indicating a lower ratio of presynaptically silent synapses. Taken together, the higher astrocytic density enhanced excitatory synaptic transmission by increasing the fraction of functional synapses through presynaptic un-silencing.


Assuntos
Astrócitos/fisiologia , Encéfalo/citologia , Neurônios/fisiologia , Sinapses/fisiologia , Transmissão Sináptica , Animais , Astrócitos/patologia , Células Cultivadas , Potenciais Pós-Sinápticos Excitadores , Feminino , Camundongos Endogâmicos ICR , Neurônios/patologia , Filogenia , Gravidez
3.
Proc Natl Acad Sci U S A ; 117(33): 20254-20264, 2020 08 18.
Artigo em Inglês | MEDLINE | ID: mdl-32747543

RESUMO

Correlated activation of cortical neurons often occurs in the brain and repetitive correlated neuronal firing could cause long-term modifications of synaptic efficacy and intrinsic excitability. We found that repetitive optogenetic activation of neuronal populations in the mouse cortex caused enhancement of optogenetically evoked firing of local coactivated neurons as well as distant cortical neurons in both ipsilateral and contralateral hemispheres. This global enhancement of evoked responses required coactivation of a sufficiently large population of neurons either within one cortical area or distributed in several areas. Enhancement of neuronal firing was saturable after repeated episodes of coactivation, diminished by inhibition of N-methyl-d-aspartic acid receptors, and accompanied by elevated excitatory postsynaptic potentials, all consistent with activity-induced synaptic potentiation. Chemogenetic inhibition of neuronal activity of the thalamus decreased the enhancement effect, suggesting thalamic involvement. Thus, correlated excitation of large neuronal populations leads to global enhancement of neuronal excitability.


Assuntos
Potenciais de Ação/fisiologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina , Excitabilidade Cortical , Corantes Fluorescentes , Masculino , Camundongos , Rede Nervosa , Transmissão Sináptica/fisiologia
4.
PLoS One ; 15(7): e0236760, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32726372

RESUMO

The neural mechanisms underlying forward suppression in the auditory cortex remain a puzzle. Little attention is paid to thalamic contribution despite the important fact that the thalamus gates upstreaming information to the auditory cortex. This study compared the time courses of forward suppression in the auditory thalamus, thalamocortical inputs and cortex using the two-tone stimulus paradigm. The preceding and succeeding tones were 20-ms long. Their frequency and amplitude were set at the characteristic frequency and 20 dB above the minimum threshold of given neurons, respectively. In the ventral division of the medial geniculate body of the thalamus, we found that the duration of complete forward suppression was about 75 ms and the duration of partial suppression was from 75 ms to about 300 ms after the onset of the preceding tone. We also found that during the partial suppression period, the responses to the succeeding tone were further suppressed in the primary auditory cortex. The forward suppression of thalamocortical field excitatory postsynaptic potentials was between those of thalamic and cortical neurons but much closer to that of thalamic ones. Our results indicate that early suppression in the cortex could result from complete suppression in the thalamus whereas later suppression may involve thalamocortical and intracortical circuitry. This suggests that the complete suppression that occurs in the thalamus provides the cortex with a "silence" window that could potentially benefit cortical processing and/or perception of the information carried by the preceding sound.


Assuntos
Córtex Auditivo/fisiologia , Potenciais Pós-Sinápticos Inibidores , Tálamo/fisiologia , Animais , Córtex Auditivo/citologia , Potenciais Pós-Sinápticos Excitadores , Feminino , Corpos Geniculados/citologia , Corpos Geniculados/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/citologia , Tálamo/citologia
5.
Nat Commun ; 11(1): 3688, 2020 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-32703948

RESUMO

Zeta inhibitory peptide (ZIP), a PKMζ inhibitor, is widely used to interfere with the maintenance of acquired memories. ZIP is able to erase memory even in the absence of PKMζ, via an unknown mechanism. We found that ZIP induces redistribution of the AMPARGluA1 in HEK293 cells and primary cortical neurons, and decreases AMPAR-mediated currents in the nucleus accumbens (NAc). These effects were mimicked by free arginine or by a modified ZIP in which all but the arginine residues were replaced by alanine. Redistribution was blocked by a peptidase-resistant version of ZIP and by treatment with the nitric oxide (NO)-synthase inhibitor L-NAME. ZIP increased GluA1-S831 phosphorylation and ZIP-induced redistribution was blocked by nitrosyl-mutant GluA1-C875S or serine-mutant GluA1-S831A. Introducing the cleavable arginine-alanine peptide into the NAc attenuated expression of cocaine-conditioned reward. Together, these results suggest that ZIP may act as an arginine donor, facilitating NO-dependent downregulation of AMPARs, thereby attenuating learning and memory.


Assuntos
Peptídeos Penetradores de Células/farmacologia , Condicionamento Psicológico/efeitos dos fármacos , Lipopeptídeos/farmacologia , Memória de Longo Prazo/efeitos dos fármacos , Óxido Nítrico/metabolismo , Receptores de AMPA/metabolismo , Animais , Cocaína/administração & dosagem , Regulação para Baixo , Endocitose/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Células HEK293 , Humanos , Potenciação de Longa Duração/efeitos dos fármacos , Masculino , Camundongos , Modelos Animais , NG-Nitroarginina Metil Éster/farmacologia , Neurônios/efeitos dos fármacos , Neurônios/fisiologia , Óxido Nítrico/antagonistas & inibidores , Núcleo Accumbens/efeitos dos fármacos , Núcleo Accumbens/fisiologia , Fosforilação , Cultura Primária de Células , Proteína Quinase C/antagonistas & inibidores , Proteína Quinase C/metabolismo , Ratos , Receptores de AMPA/genética , Recompensa , Técnicas Estereotáxicas
6.
Nat Commun ; 11(1): 2784, 2020 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-32493971

RESUMO

The orbitofrontal cortex (OFC) encodes expected outcomes and plays a critical role in flexible, outcome-guided behavior. The OFC projects to primary visual cortex (V1), yet the function of this top-down projection is unclear. We find that optogenetic activation of OFC projection to V1 reduces the amplitude of V1 visual responses via the recruitment of local somatostatin-expressing (SST) interneurons. Using mice performing a Go/No-Go visual task, we show that the OFC projection to V1 mediates the outcome-expectancy modulation of V1 responses to the reward-irrelevant No-Go stimulus. Furthermore, V1-projecting OFC neurons reduce firing during expectation of reward. In addition, chronic optogenetic inactivation of OFC projection to V1 impairs, whereas chronic activation of SST interneurons in V1 improves the learning of Go/No-Go visual task, without affecting the immediate performance. Thus, OFC top-down projection to V1 is crucial to drive visual associative learning by modulating the response gain of V1 neurons to non-relevant stimulus.


Assuntos
Aprendizagem/fisiologia , Córtex Pré-Frontal/fisiologia , Córtex Visual/fisiologia , Animais , Axônios/fisiologia , Axônios/efeitos da radiação , Comportamento Animal , Potenciais Pós-Sinápticos Excitadores/efeitos da radiação , Potenciais Pós-Sinápticos Inibidores/efeitos da radiação , Lasers , Luz , Camundongos Endogâmicos C57BL , Estimulação Luminosa , Córtex Pré-Frontal/efeitos da radiação , Recompensa , Análise e Desempenho de Tarefas , Córtex Visual/efeitos da radiação
7.
Nat Commun ; 11(1): 3012, 2020 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-32541656

RESUMO

The complex relationship between specific hippocampal oscillation frequency deficit and cognitive dysfunction in the ischemic brain is unclear. Here, using a mouse two-vessel occlusion (2VO) cerebral ischemia model, we show that visual stimulation with a 40 Hz light flicker drove hippocampal CA1 slow gamma and restored 2VO-induced reduction in CA1 slow gamma power and theta-low gamma phase-amplitude coupling, but not those of the high gamma. Low gamma frequency lights at 30 Hz, 40 Hz, and 50 Hz, but not 10 Hz, 80 Hz, and arrhythmic frequency light, were protective against degenerating CA1 neurons after 2VO, demonstrating the importance of slow gamma in cognitive functions after cerebral ischemia. Mechanistically, 40 Hz light flicker enhanced RGS12-regulated CA3-CA1 presynaptic N-type calcium channel-dependent short-term synaptic plasticity and associated postsynaptic long term potentiation (LTP) after 2VO. These results support a causal relationship between CA1 slow gamma and cognitive dysfunctions in the ischemic brain.


Assuntos
Região CA1 Hipocampal/fisiologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Ritmo Gama/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Animais , Isquemia Encefálica/fisiopatologia , Região CA1 Hipocampal/irrigação sanguínea , Circulação Cerebrovascular/fisiologia , Estimulação Elétrica , Masculino , Aprendizagem em Labirinto/fisiologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Atividade Motora/fisiologia , Estimulação Luminosa
8.
PLoS One ; 15(6): e0234394, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32574176

RESUMO

In the BACHD mouse model of Huntington's disease (HD), deletion of the N17 domain of the Huntingtin gene (BACHDΔN17, Q97) has been reported to lead to nuclear accumulation of mHTT and exacerbation of motor deficits, neuroinflammation and striatal atrophy (Gu et al., 2015). Here we characterized the effect of N17 deletion on dorsolateral striatal medium spiny neurons (MSNs) in BACHDΔN17 (Q97) and BACWTΔN17 (Q31) mice by comparing them to MSNs in wildtype (WT) mice. Mice were characterized on a series of motor tasks and subsequently whole cell patch clamp recordings with simultaneous biocytin filling of MSNs in in vitro striatal slices from these mice were used to comprehensively assess their physiological and morphological features. Key findings include that: Q97 mice exhibit impaired gait and righting reflexes but normal tail suspension reflexes and normal coats while Q31 mice do not differ from WT; intrinsic membrane and action potential properties are altered -but differentially so- in MSNs from Q97 and from Q31 mice; excitatory and inhibitory synaptic currents exhibit higher amplitudes in Q31 but not Q97 MSNs, while excitatory synaptic currents occur at lower frequency in Q97 than in WT and Q31 MSNs; there is a reduced total dendritic length in Q31 -but not Q97- MSNs compared to WT, while spine density and number did not differ in MSNs in the three groups. The findings that Q31 MSNs differed from Q97 and WT neurons with regard to some physiological features and structurally suggest a novel role of the N17 domain in the function of WT Htt. The motor phenotype seen in Q97 mice was less robust than that reported in an earlier study (Gu et al., 2015), and the alterations to MSN physiological properties were largely consistent with changes reported previously in a number of other mouse models of HD. Together this study indicates that N17 plays a role in the modulation of the properties of MSNs in both mHtt and WT-Htt mice, but does not markedly exacerbate HD-like pathogenesis in the BACHD model.


Assuntos
Proteína Huntingtina/genética , Doença de Huntington/genética , Potenciais de Ação , Animais , Corpo Estriado/patologia , Corpo Estriado/fisiopatologia , Dendritos/patologia , Modelos Animais de Doenças , Potenciais Pós-Sinápticos Excitadores , Feminino , Humanos , Proteína Huntingtina/química , Proteína Huntingtina/fisiologia , Doença de Huntington/patologia , Doença de Huntington/fisiopatologia , Coxeadura Animal/genética , Coxeadura Animal/fisiopatologia , Masculino , Camundongos , Camundongos Mutantes , Camundongos Transgênicos , Proteínas Mutantes/química , Proteínas Mutantes/genética , Proteínas Mutantes/fisiologia , Neurônios/patologia , Neurônios/fisiologia , Domínios Proteicos , Reflexo Anormal/genética , Reflexo Anormal/fisiologia , Deleção de Sequência
9.
Nat Neurosci ; 23(6): 741-753, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32393895

RESUMO

During sleep and awake rest, the neocortex generates large-scale slow-wave (SW) activity. Here, we report that the claustrum coordinates neocortical SW generation. We established a transgenic mouse line that enabled the genetic interrogation of a subpopulation of claustral glutamatergic neurons. These neurons received inputs from and sent outputs to widespread neocortical areas. The claustral neuronal firings mostly correlated with cortical SW activity. In vitro optogenetic stimulation of the claustrum induced excitatory postsynaptic responses in most neocortical neurons, but elicited action potentials primarily in inhibitory interneurons. In vivo optogenetic stimulation induced a synchronized down-state featuring prolonged silencing of neural activity in all layers of many cortical areas, followed by a down-to-up state transition. In contrast, genetic ablation of claustral neurons attenuated SW activity in the frontal cortex. These results demonstrate a crucial role of claustral neurons in synchronizing inhibitory interneurons across wide cortical areas for the spatiotemporal coordination of SW activity.


Assuntos
Claustrum/fisiologia , Neocórtex/fisiologia , Sono de Ondas Lentas/fisiologia , Potenciais de Ação/fisiologia , Animais , Potenciais Pós-Sinápticos Excitadores/fisiologia , Interneurônios/fisiologia , Camundongos , Camundongos Transgênicos , Inibição Neural/fisiologia , Neurônios/fisiologia , Optogenética , Proteínas com Domínio T/genética
10.
PLoS Biol ; 18(4): e3000717, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32353004

RESUMO

Extensive evidence links Glutamate receptor, ionotropic, NMDA2B (GRIN2B), encoding the GluN2B/NR2B subunit of N-methyl-D-aspartate receptors (NMDARs), with various neurodevelopmental disorders, including autism spectrum disorders (ASDs), but the underlying mechanisms remain unclear. In addition, it remains unknown whether mutations in GluN2B, which starts to be expressed early in development, induces early pathophysiology that can be corrected by early treatments for long-lasting effects. We generated and characterized Grin2b-mutant mice that carry a heterozygous, ASD-risk C456Y mutation (Grin2b+/C456Y). In Grin2b+/C456Y mice, GluN2B protein levels were strongly reduced in association with decreased hippocampal NMDAR currents and NMDAR-dependent long-term depression (LTD) but unaltered long-term potentiation, indicative of mutation-induced protein degradation and LTD sensitivity. Behaviorally, Grin2b+/C456Y mice showed normal social interaction but exhibited abnormal anxiolytic-like behavior. Importantly, early, but not late, treatment of young Grin2b+/C456Y mice with the NMDAR agonist D-cycloserine rescued NMDAR currents and LTD in juvenile mice and improved anxiolytic-like behavior in adult mice. Therefore, GluN2B-C456Y haploinsufficiency decreases GluN2B protein levels, NMDAR-dependent LTD, and anxiety-like behavior, and early activation of NMDAR function has long-lasting effects on adult mouse behavior.


Assuntos
Ansiedade/genética , Hipocampo/fisiologia , Depressão Sináptica de Longo Prazo/fisiologia , Receptores de N-Metil-D-Aspartato/genética , Animais , Ansiedade/fisiopatologia , Comportamento Animal/efeitos dos fármacos , Ciclosserina/farmacologia , Potenciais Pós-Sinápticos Excitadores/genética , Técnicas de Introdução de Genes , Haploinsuficiência/genética , Heterozigoto , Hipocampo/metabolismo , Depressão Sináptica de Longo Prazo/efeitos dos fármacos , Camundongos Mutantes , Mutação , Proteínas do Tecido Nervoso/metabolismo , Receptores de N-Metil-D-Aspartato/agonistas , Receptores de N-Metil-D-Aspartato/metabolismo
11.
J Neurosci ; 40(21): 4090-4102, 2020 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-32312887

RESUMO

Neurons can respond to decreased network activity with a homeostatic increase in the amplitudes of miniature EPSCs (mEPSCs). The prevailing view is that mEPSC amplitudes are uniformly multiplied by a single factor, termed "synaptic scaling." Deviations from purely multiplicative scaling have been attributed to biological differences, or to a distortion imposed by a detection threshold limit. Here, we demonstrate in neurons dissociated from cortices of male and female mice that the shift in mEPSC amplitudes observed in the experimental data cannot be reproduced by simulation of uniform multiplicative scaling, with or without the distortion caused by applying a detection threshold. Furthermore, we demonstrate explicitly that the scaling factor is not uniform but is close to 1 for small mEPSCs, and increases with increasing mEPSC amplitude across a substantial portion of the data. This pattern was also observed for previously published data from dissociated mouse hippocampal neurons and dissociated rat cortical neurons. The finding of "divergent scaling" shifts the current view of homeostatic plasticity as a process that alters all synapses on a neuron equally to one that must accommodate the differential effect observed for small versus large mEPSCs. Divergent scaling still accomplishes the essential homeostatic task of modifying synaptic strengths in the opposite direction of the activity change, but the consequences are greatest for those synapses which individually are more likely to bring a neuron to threshold.SIGNIFICANCE STATEMENT In homeostatic plasticity, the responses to chronic increases or decreases in network activity act in the opposite direction to restore normal activity levels. Homeostatic plasticity is likely to play a role in diseases associated with long-term changes in brain function, such as epilepsy and neuropsychiatric illnesses. One homeostatic response is the increase in synaptic strength following a chronic block of activity. Research is focused on finding a globally expressed signaling pathway, because it has been proposed that the plasticity is uniformly expressed across all synapses. Here, we show that the plasticity is not uniform. Our work suggests that homeostatic signaling molecules are likely to be differentially expressed across synapses.


Assuntos
Córtex Cerebral/fisiologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Potenciais Pós-Sinápticos em Miniatura/fisiologia , Plasticidade Neuronal/fisiologia , Neurônios/fisiologia , Animais , Células Cultivadas , Camundongos , Técnicas de Patch-Clamp , Sinapses/fisiologia , Transmissão Sináptica/fisiologia
12.
Anesthesiology ; 133(1): 165-184, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32349075

RESUMO

BACKGROUND: Brain-derived estrogen is implicated in pain-related aversion; however, which estrogen receptors mediate this effect remains unclear. This study hypothesized that the different estrogen receptors in the rostral anterior cingulate cortex play distinct roles in pain-related aversion. METHODS: Formalin-induced conditioned place avoidance and place escape/avoidance paradigms were used to evaluate pain-related aversion in rodents. Immunohistochemistry and Western blotting were used to detect estrogen receptor expression. Patch-clamp recordings were used to examine N-methyl-D-aspartate-mediated excitatory postsynaptic currents in rostral anterior cingulate cortex slices. RESULTS: The administration of the estrogen receptor-ß antagonist 4-(2-phenyl-5,7-bis [trifluoromethyl] pyrazolo [1,5-a] pyrimidin-3-yl) phenol (PHTPP) or the G protein-coupled estrogen receptor-1 antagonist (3aS*,4R*,9bR*)-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-3H-cyclopenta [c] quinolone (G15) but not the estrogen receptor-α antagonist 1,3-bis (4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy) phenol]-1H-pyrazole dihydrochloride (MPP) into the rostral anterior cingulate cortex blocked pain-related aversion in rats (avoidance score, mean ± SD: 1,3-bis [4-hydroxyphenyl]-4-methyl-5-(4-[2-piperidinylethoxy] phenol)-1H-pyrazole dihydrochloride (MPP): 47.0 ± 18.9%, 4-(2-phenyl-5,7-bis [trifluoromethyl] pyrazolo [1,5-a] pyrimidin-3-yl) phenol (PHTPP): -7.4 ± 20.6%, and [3aS*,4R*,9bR*]-4-[6-bromo-1,3-benzodioxol-5-yl]-3a,4,5,9b-3H-cyclopenta [c] quinolone (G15): -4.6 ± 17.0% vs. vehicle: 46.5 ± 12.2%; n = 7 to 9; P < 0.0001). Consistently, estrogen receptor-ß knockdown but not estrogen receptor-α knockdown by short-hairpin RNA also inhibited pain-related aversion in mice (avoidance score, mean ± SD: estrogen receptor-α-short-hairpin RNA: 26.0 ± 7.1% and estrogen receptor-ß-short-hairpin RNA: 6.3 ± 13.4% vs. control short-hairpin RNA: 29.1 ± 9.1%; n = 7 to 10; P < 0.0001). Furthermore, the direct administration of the estrogen receptor-ß agonist 2,3-bis (4-hydroxyphenyl)-propionitrile (DPN) or the G protein-coupled estrogen receptor-1 agonist (±)-1-([3aR*,4S*,9bS*]-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta [c]quinolin-8-yl)-ethanone (G1) into the rostral anterior cingulate cortex resulted in conditioned place avoidance (avoidance score, mean ± SD: 2,3-bis (4-hydroxyphenyl)-propionitrile (DPN): 35.3 ± 9.5% and (±)-1-([3aR*,4S*,9bS*]-4-(6-bromo-1,3-benzodioxol-5-yl)-3a,4,5,9b-tetrahydro-3H-cyclopenta [c]quinolin-8-yl)-ethanone (G1): 43.5 ± 22.8% vs. vehicle: 0.3 ± 14.9%; n = 8; P < 0.0001) but did not affect mechanical or thermal sensitivity. The activation of the estrogen receptor-ß/protein kinase A or G protein-coupled estrogen receptor-1/protein kinase B pathway elicited the long-term potentiation of N-methyl-D-aspartate-mediated excitatory postsynaptic currents. CONCLUSIONS: These findings indicate that estrogen receptor-ß and G protein-coupled estrogen receptor-1 but not estrogen receptor-α in the rostral anterior cingulate cortex contribute to pain-related aversion by modulating N-methyl-D-aspartate receptor-mediated excitatory synaptic transmission.


Assuntos
Giro do Cíngulo/fisiopatologia , Dor/fisiopatologia , Dor/psicologia , Receptores Estrogênicos , Animais , Aprendizagem da Esquiva , Proteínas Quinases Dependentes de AMP Cíclico/genética , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de GMP Cíclico/genética , Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , Antagonistas de Estrogênios/farmacologia , Receptor beta de Estrogênio/efeitos dos fármacos , Receptor beta de Estrogênio/genética , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Feminino , Técnicas de Silenciamento de Genes , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Técnicas de Patch-Clamp , RNA Interferente Pequeno , Ratos , Ratos Sprague-Dawley , Receptores Estrogênicos/efeitos dos fármacos , Receptores Estrogênicos/genética
13.
J Neurosci ; 40(21): 4103-4115, 2020 05 20.
Artigo em Inglês | MEDLINE | ID: mdl-32327530

RESUMO

Volatile anesthetics are widely used for surgery, but neuronal mechanisms of anesthesia remain unidentified. At the calyx of Held in brainstem slices from rats of either sex, isoflurane at clinical doses attenuated EPSCs by decreasing the release probability and the number of readily releasable vesicles. In presynaptic recordings of Ca2+ currents and exocytic capacitance changes, isoflurane attenuated exocytosis by inhibiting Ca2+ currents evoked by a short presynaptic depolarization, whereas it inhibited exocytosis evoked by a prolonged depolarization via directly blocking exocytic machinery downstream of Ca2+ influx. Since the length of presynaptic depolarization can simulate the frequency of synaptic inputs, isoflurane anesthesia is likely mediated by distinct dual mechanisms, depending on input frequencies. In simultaneous presynaptic and postsynaptic action potential recordings, isoflurane impaired the fidelity of repetitive spike transmission, more strongly at higher frequencies. Furthermore, in the cerebrum of adult mice, isoflurane inhibited monosynaptic corticocortical spike transmission, preferentially at a higher frequency. We conclude that dual presynaptic mechanisms operate for the anesthetic action of isoflurane, of which direct inhibition of exocytic machinery plays a low-pass filtering role in spike transmission at central excitatory synapses.SIGNIFICANCE STATEMENT Synaptic mechanisms of general anesthesia remain unidentified. In rat brainstem slices, isoflurane inhibits excitatory transmitter release by blocking presynaptic Ca2+ channels and exocytic machinery, with the latter mechanism predominating in its inhibitory effect on high-frequency transmission. Both in slice and in vivo, isoflurane preferentially inhibits spike transmission induced by high-frequency presynaptic inputs. This low-pass filtering action of isoflurane likely plays a significant role in general anesthesia.


Assuntos
Anestésicos Inalatórios/administração & dosagem , Tronco Encefálico/efeitos dos fármacos , Isoflurano/administração & dosagem , Neurônios/efeitos dos fármacos , Terminações Pré-Sinápticas/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Animais , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Exocitose/efeitos dos fármacos , Feminino , Masculino , Camundongos , Técnicas de Patch-Clamp , Ratos , Ratos Wistar
14.
Neuron ; 106(5): 842-854.e4, 2020 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-32213321

RESUMO

Excitation in neural circuits must be carefully controlled by inhibition to regulate information processing and network excitability. During development, cortical inhibitory and excitatory inputs are initially mismatched but become co-tuned or balanced with experience. However, little is known about how excitatory-inhibitory balance is defined at most synapses or about the mechanisms for establishing or maintaining this balance at specific set points. Here we show how coordinated long-term plasticity calibrates populations of excitatory-inhibitory inputs onto mouse auditory cortical pyramidal neurons. Pairing pre- and postsynaptic activity induced plasticity at paired inputs and different forms of heterosynaptic plasticity at the strongest unpaired synapses, which required minutes of activity and dendritic Ca2+ signaling to be computed. Theoretical analyses demonstrated how the relative rate of heterosynaptic plasticity could normalize and stabilize synaptic strengths to achieve any possible excitatory-inhibitory correlation. Thus, excitatory-inhibitory balance is dynamic and cell specific, determined by distinct plasticity rules across multiple excitatory and inhibitory synapses.


Assuntos
Potenciais de Ação/fisiologia , Córtex Auditivo/fisiologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Potenciais Pós-Sinápticos Inibidores/fisiologia , Inibição Neural/fisiologia , Plasticidade Neuronal/fisiologia , Células Piramidais/fisiologia , Animais , Sinalização do Cálcio , Potenciais Evocados , Potenciação de Longa Duração/fisiologia , Camundongos , Técnicas de Patch-Clamp , Sinapses/fisiologia
15.
Mol Pharmacol ; 97(5): 336-350, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32111699

RESUMO

Positive allosteric modulators (PAMs) of AMPA receptors boost cognitive performance in preclinical and clinical studies. Their therapeutic window is narrow, however, and clinical application will likely only occur if greater discrimination in activity is achieved. Toward that end, we compared the modulatory activity of two PAMs recently considered as clinical candidates, LY451395 (mibampator) and PF-04958242/BIIB104, on recombinant and native AMPA receptors (AMPARs). We found that the principle molecular determinant that shaped modulatory activity of both PAMs on deactivation (recombinant) and decay (synaptic) of AMPARs was the auxiliary protein incorporated into the receptor complexes. AMPARs containing the stargazin/γ2 transmembrane AMPAR regulatory protein (TARP) were slowed to a >10-fold degree by both PAMs as compared with those incorporating γ8 TARP. Neither subunit composition nor flip/flop splice variation had substantive effect. Similarly, stargazin/γ2-containing mossy fiber EPSCs in cerebellar granule neurons were slowed to a ∼5-fold greater degree than EPSCs in hippocampal CA1 pyramidal cell neurons, which express the γ8 TARP. LY451395 exhibited greater efficacy than BIIB104 at both synapses. These studies provide insight into the receptor constituents that determine efficacy of sulfonamide PAMs. We conclude that compounds that discriminate between AMPARs complexed with distinct TARPs, and particularly those with lower stargazin/γ2 efficacy such as BIIB104, could act as viable procognitive therapeutics. SIGNIFICANCE STATEMENT: Positive allosteric modulators (PAMs) of AMPA receptors enhance cognitive function in a variety of preclinical models. A clearer understanding of the critical determinants of PAM activity could yield critical insight into pathways to maximize their therapeutic index. Here we show that auxiliary proteins for AMPARs play a major, but thus far underappreciated, role in shaping recombinant and neuronal AMPAR modulation by two clinical candidate PAMs. These data will inform both clinical outcomes as well as future rational development of new modulators.


Assuntos
Proteínas de Membrana/metabolismo , Receptores de AMPA/metabolismo , Regulação Alostérica/efeitos dos fármacos , Animais , Compostos de Bifenilo/farmacologia , Cerebelo/metabolismo , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Feminino , Células HEK293 , Hipocampo/metabolismo , Humanos , Masculino , Camundongos Endogâmicos C57BL , Multimerização Proteica/efeitos dos fármacos , Subunidades Proteicas/metabolismo , Pirimidinas/farmacologia , Sulfonamidas/farmacologia , Sinapses/efeitos dos fármacos , Sinapses/metabolismo , Resultado do Tratamento , Triazóis/farmacologia
16.
J Neurosci ; 40(15): 3063-3074, 2020 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-32139583

RESUMO

The cerebellum influences motor control through Purkinje target neurons, which transmit cerebellar output. Such output is required, for instance, for larval zebrafish to learn conditioned fictive swimming. The output cells, called eurydendroid neurons (ENs) in teleost fish, are inhibited by Purkinje cells and excited by parallel fibers. Here, we investigated the electrophysiological properties of glutamatergic ENs labeled by the transcription factor olig2. Action potential firing and synaptic responses were recorded in current clamp and voltage clamp from olig2+ neurons in immobilized larval zebrafish (before sexual differentiation) and were correlated with motor behavior by simultaneous recording of fictive swimming. In the absence of swimming, olig2+ ENs had basal firing rates near 8 spikes/s, and EPSCs and IPSCs were evident. Comparing Purkinje firing rates and eurydendroid IPSC rates indicated that 1-3 Purkinje cells converge onto each EN. Optogenetically suppressing Purkinje simple spikes, while preserving complex spikes, suggested that eurydendroid IPSC size depended on presynaptic spike duration rather than amplitude. During swimming, EPSC and IPSC rates increased. Total excitatory and inhibitory currents during sensory-evoked swimming were both more than double those during spontaneous swimming. During both spontaneous and sensory-evoked swimming, the total inhibitory current was more than threefold larger than the excitatory current. Firing rates of ENs nevertheless increased, suggesting that the relative timing of IPSCs and EPSCs may permit excitation to drive additional eurydendroid spikes. The data indicate that olig2+ cells are ENs whose activity is modulated with locomotion, suiting them to participate in sensorimotor integration associated with cerebellum-dependent learning.SIGNIFICANCE STATEMENT The cerebellum contributes to movements through signals generated by cerebellar output neurons, called eurydendroid neurons (ENs) in fish (cerebellar nuclei in mammals). ENs receive sensory and motor signals from excitatory parallel fibers and inhibitory Purkinje cells. Here, we report electrophysiological recordings from ENs of larval zebrafish that directly illustrate how synaptic inhibition and excitation are integrated by cerebellar output neurons in association with motor behavior. The results demonstrate that inhibitory and excitatory drive both increase during fictive swimming, but inhibition greatly exceeds excitation. Firing rates nevertheless increase, providing evidence that synaptic integration promotes cerebellar output during locomotion. The data offer a basis for comparing aspects of cerebellar coding that are conserved and that diverge across vertebrates.


Assuntos
Cerebelo/fisiologia , Neurônios/fisiologia , Fator de Transcrição 2 de Oligodendrócitos/fisiologia , Natação/fisiologia , Sinapses/fisiologia , Proteínas de Peixe-Zebra/fisiologia , Peixe-Zebra/fisiologia , Potenciais de Ação/fisiologia , Animais , Animais Geneticamente Modificados , Fenômenos Eletrofisiológicos/fisiologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Larva , Optogenética , Técnicas de Patch-Clamp , Células de Purkinje/fisiologia
17.
Neuron ; 106(5): 769-777.e4, 2020 06 03.
Artigo em Inglês | MEDLINE | ID: mdl-32199104

RESUMO

Mutations in Shank3 are strongly associated with autism spectrum disorders and neural circuit changes in several brain areas, but the cellular mechanisms that underlie these defects are not understood. Homeostatic forms of plasticity allow central circuits to maintain stable function during experience-dependent development, leading us to ask whether loss of Shank3 might impair homeostatic plasticity and circuit-level compensation to perturbations. We found that Shank3 loss in vitro abolished synaptic scaling and intrinsic homeostatic plasticity, deficits that could be rescued by treatment with lithium. Further, Shank3 knockout severely compromised the in vivo ability of visual cortical circuits to recover from perturbations to sensory drive. Finally, lithium treatment ameliorated a repetitive self-grooming phenotype in Shank3 knockout mice. These findings demonstrate that Shank3 loss severely impairs the ability of central circuits to harness homeostatic mechanisms to compensate for perturbations in drive, which, in turn, may render them more vulnerable to such perturbations.


Assuntos
Homeostase/genética , Proteínas do Tecido Nervoso/genética , Plasticidade Neuronal/genética , Neurônios/efeitos dos fármacos , Córtex Visual/efeitos dos fármacos , Animais , Antimaníacos/farmacologia , Transtorno Autístico/genética , Comportamento Animal/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/genética , Técnicas de Silenciamento de Genes , Quinase 3 da Glicogênio Sintase/antagonistas & inibidores , Asseio Animal/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Compostos de Lítio/farmacologia , Camundongos , Camundongos Knockout , Proteínas do Tecido Nervoso/efeitos dos fármacos , Vias Neurais , Plasticidade Neuronal/efeitos dos fármacos , Neurônios/metabolismo , Ratos , Bloqueadores dos Canais de Sódio/farmacologia , Tetrodotoxina/farmacologia , Córtex Visual/citologia , Córtex Visual/metabolismo
18.
PLoS One ; 15(2): e0228348, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32032373

RESUMO

The synaptic vesicle protein, synaptotagmin, is the principle Ca2+ sensor for synaptic transmission. Ca2+ influx into active nerve terminals is translated into neurotransmitter release by Ca2+ binding to synaptotagmin's tandem C2 domains, triggering the fast, synchronous fusion of multiple synaptic vesicles. Two hydrophobic residues, shown to mediate Ca2+-dependent membrane insertion of these C2 domains, are required for this process. Previous research suggested that one of its tandem C2 domains (C2B) is critical for fusion, while the other domain (C2A) plays only a facilitatory role. However, the function of the two hydrophobic residues in C2A have not been adequately tested in vivo. Here we show that these two hydrophobic residues are absolutely required for synaptotagmin to trigger vesicle fusion. Using in vivo electrophysiological recording at the Drosophila larval neuromuscular junction, we found that mutation of these two key C2A hydrophobic residues almost completely abolished neurotransmitter release. Significantly, mutation of both hydrophobic residues resulted in more severe deficits than those seen in synaptotagmin null mutants. Thus, we report the most severe phenotype of a C2A mutation to date, demonstrating that the C2A domain is absolutely essential for synaptotagmin's function as the electrostatic switch.


Assuntos
Cálcio/metabolismo , Proteínas de Drosophila/metabolismo , Transmissão Sináptica , Sinaptotagminas/metabolismo , Sequência de Aminoácidos , Animais , Animais Geneticamente Modificados/metabolismo , Drosophila/crescimento & desenvolvimento , Drosophila/metabolismo , Proteínas de Drosophila/química , Proteínas de Drosophila/genética , Potenciais Pós-Sinápticos Excitadores , Humanos , Larva/metabolismo , Larva/fisiologia , Mutagênese Sítio-Dirigida , Junção Neuromuscular/metabolismo , Neurotransmissores/metabolismo , Ligação Proteica , Domínios Proteicos , Estrutura Terciária de Proteína , Alinhamento de Sequência , Sinaptotagminas/química , Sinaptotagminas/genética
19.
PLoS Genet ; 16(1): e1008587, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-32004315

RESUMO

Perturbation of synapse development underlies many inherited neurodevelopmental disorders including intellectual disability (ID). Diverse mutations on the human TBC1D24 gene are strongly associated with epilepsy and ID. However, the physiological function of TBC1D24 in the brain is not well understood, and there is a lack of genetic mouse model that mimics TBC1D24 loss-of-function for the study of animal behaviors. Here we report that TBC1D24 is present at the postsynaptic sites of excitatory synapses, where it is required for the maintenance of dendritic spines through inhibition of the small GTPase ARF6. Mice subjected to viral-mediated knockdown of TBC1D24 in the adult hippocampus display dendritic spine loss, deficits in contextual fear memory, as well as abnormal behaviors including hyperactivity and increased anxiety. Interestingly, we show that the protein stability of TBC1D24 is diminished by the disease-associated missense mutation that leads to F251L amino acid substitution. We further generate the F251L knock-in mice, and the homozygous mutants show increased neuronal excitability, spontaneous seizure and pre-mature death. Moreover, the heterozygous F251L knock-in mice survive into adulthood but display dendritic spine defects and impaired memory. Our findings therefore uncover a previously uncharacterized postsynaptic function of TBC1D24, and suggest that impaired dendritic spine maintenance contributes to the pathophysiology of individuals harboring TBC1D24 gene mutations. The F251L knock-in mice represent a useful animal model for investigation of the mechanistic link between TBC1D24 loss-of-function and neurodevelopmental disorders.


Assuntos
Epilepsia/genética , Potenciais Pós-Sinápticos Excitadores , Proteínas Ativadoras de GTPase/genética , Deficiência Intelectual/genética , Animais , Células Cultivadas , Hipocampo/metabolismo , Hipocampo/patologia , Hipocampo/fisiologia , Memória , Camundongos , Camundongos Endogâmicos C57BL , Mutação de Sentido Incorreto , Neurônios/metabolismo , Neurônios/patologia , Neurônios/fisiologia
20.
Nat Commun ; 11(1): 697, 2020 02 04.
Artigo em Inglês | MEDLINE | ID: mdl-32019929

RESUMO

The integration of synaptic inputs onto dendrites provides the basis for neuronal computation. Whereas recent studies have begun to outline the spatial organization of synaptic inputs on individual neurons, the underlying principles related to the specific neural functions are not well understood. Here we perform two-photon dendritic imaging with a genetically-encoded glutamate sensor in awake monkeys, and map the excitatory synaptic inputs on dendrites of individual V1 superficial layer neurons with high spatial and temporal resolution. We find a functional integration and trade-off between orientation-selective and color-selective inputs in basal dendrites of individual V1 neurons. Synaptic inputs on dendrites are spatially clustered by stimulus feature, but functionally scattered in multidimensional feature space, providing a potential substrate of local feature integration on dendritic branches. Furthermore, apical dendrite inputs have larger receptive fields and longer response latencies than basal dendrite inputs, suggesting a dominant role for apical dendrites in integrating feedback in visual information processing.


Assuntos
Neurônios/fisiologia , Navegação Espacial , Animais , Dendritos/fisiologia , Potenciais Pós-Sinápticos Excitadores , Macaca , Modelos Neurológicos , Sinapses/fisiologia
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