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1.
J Pharmacol Sci ; 144(4): 212-217, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33070840

RESUMO

The hippocampus is a brain region well-known to exhibit structural and functional changes in temporal lobe epilepsy. Studies analyzing the brains of patients with epilepsy and those from animal models of epilepsy have revealed that microglia are excessively activated, especially in the hippocampus. These findings suggest that microglia may contribute to the onset and aggravation of epilepsy; however, direct evidence for microglial involvement or the underlying mechanisms by which this occurs remain to be fully discovered. To date, neuron-microglia interactions have been vigorously studied in adult epilepsy models; such studies have clarified microglial responses to excessive synchronous firing of neurons. In contrast, the role of microglia in the postnatal brain of patients with epileptic seizures remain largely unclear. Some early-life seizures, such as complex febrile seizures, have been shown to cause structural and functional changes in the brain, which is a risk factor for future development of epilepsy. Because brain structure and function are actively modulated by microglia in both health and disease, it is essential to clarify the role of microglia in early-life seizures and its impact on epileptogenesis.


Assuntos
Comunicação Celular , Epilepsia do Lobo Temporal/etiologia , Epilepsia do Lobo Temporal/patologia , Hipocampo/citologia , Hipocampo/patologia , Microglia/patologia , Microglia/fisiologia , Fatores Etários , Idade de Início , Animais , Giro Denteado/citologia , Giro Denteado/patologia , Modelos Animais de Doenças , Humanos , Camundongos , Neurônios/fisiologia , Ratos , Fatores de Risco , Convulsões Febris/etiologia , Convulsões Febris/patologia , Sinapses/fisiologia
2.
J Vis Exp ; (163)2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32986037

RESUMO

One of the most important things in the field of adult hippocampal neurogenesis (AHN) is the identification of the newly generated cells. The immunodetection of thymidine analogs (such as 5-Bromo-2'-deoxyuridine (BrdU)) is a standard technique used for visualizing these newly generated cells. Therefore, BrdU is usually injected in small animals intraperitoneally, so the thymidine analog gets incorporated into dividing cells during DNA synthesis. Detection is performed by immunohistochemical analysis of brain slices. Every research group that has been using this technique can appreciate that it requires special attention to minute details to achieve a successful stain. For instance, an important step is DNA denaturation with HCl, which allows it to reach the cell nucleus to stain it. However, the existing scientific reports describe very few of such steps in detail. Therefore, standardizing the technique is challenging for new laboratories as it can take several months to yield positive and successful outcomes. The purpose of this work is to describe and elaborate the steps to obtain positive and successful outcomes of the immunostaining technique in detail when working with the thymidine analog BrdU. The protocol includes the reagent preparation and setup, administration of thymidine analog in a rodent, transcardial perfusion, tissue preparation, peroxidase immunohistochemical reaction, use of avidin-biotin complex, immunofluorescence, counterstaining, microscopy imaging, and cell analysis.


Assuntos
Bromodesoxiuridina/metabolismo , Imuno-Histoquímica/métodos , Neurogênese , Timidina/análogos & derivados , Animais , Antígenos/metabolismo , Forma do Núcleo Celular , Proliferação de Células , Giro Denteado/citologia , Dissecação , Imunofluorescência , Processamento de Imagem Assistida por Computador , Imageamento Tridimensional , Masculino , Ratos Wistar , Fixação de Tecidos
3.
Nat Commun ; 11(1): 4275, 2020 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-32848155

RESUMO

New neurons are generated in adult mammals. Adult hippocampal neurogenesis is considered to play an important role in cognition and mental health. The number and properties of newly born neurons are regulatable by a broad range of physiological and pathological conditions. To begin to understand the underlying cellular mechanisms and functional relevance of adult neurogenesis, many studies rely on quantification of adult-born neurons. However, lack of standardized methods to quantify new neurons is impeding research reproducibility across laboratories. Here, we review the importance of stereology, and propose why and how it should be applied to the study of adult neurogenesis.


Assuntos
Encéfalo/citologia , Encéfalo/fisiologia , Células-Tronco Neurais/citologia , Células-Tronco Neurais/fisiologia , Neurogênese/fisiologia , Adulto , Células-Tronco Adultas/citologia , Células-Tronco Adultas/fisiologia , Animais , Giro Denteado/citologia , Giro Denteado/fisiologia , Humanos , Modelos Neurológicos , Plasticidade Neuronal
4.
Neuron ; 107(6): 1212-1225.e7, 2020 09 23.
Artigo em Inglês | MEDLINE | ID: mdl-32763145

RESUMO

Dentate gyrus granule cells (GCs) connect the entorhinal cortex to the hippocampal CA3 region, but how they process spatial information remains enigmatic. To examine the role of GCs in spatial coding, we measured excitatory postsynaptic potentials (EPSPs) and action potentials (APs) in head-fixed mice running on a linear belt. Intracellular recording from morphologically identified GCs revealed that most cells were active, but activity level varied over a wide range. Whereas only ∼5% of GCs showed spatially tuned spiking, ∼50% received spatially tuned input. Thus, the GC population broadly encodes spatial information, but only a subset relays this information to the CA3 network. Fourier analysis indicated that GCs received conjunctive place-grid-like synaptic input, suggesting code conversion in single neurons. GC firing was correlated with dendritic complexity and intrinsic excitability, but not extrinsic excitatory input or dendritic cable properties. Thus, functional maturation may control input-output transformation and spatial code conversion.


Assuntos
Região CA3 Hipocampal/fisiologia , Giro Denteado/fisiologia , Potenciais Pós-Sinápticos Excitadores , Neurônios/fisiologia , Navegação Espacial , Potenciais de Ação , Animais , Região CA3 Hipocampal/citologia , Células Cultivadas , Giro Denteado/citologia , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL
5.
Neuron ; 107(3): 552-565.e10, 2020 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-32502462

RESUMO

The occurrence of dreaming during rapid eye movement (REM) sleep prompts interest in the role of REM sleep in hippocampal-dependent episodic memory. Within the mammalian hippocampus, the dentate gyrus (DG) has the unique characteristic of exhibiting neurogenesis persisting into adulthood. Despite their small numbers and sparse activity, adult-born neurons (ABNs) in the DG play critical roles in memory; however, their memory function during sleep is unknown. Here, we investigate whether young ABN activity contributes to memory consolidation during sleep using Ca2+ imaging in freely moving mice. We found that contextual fear learning recruits a population of young ABNs that are reactivated during subsequent REM sleep against a backdrop of overall reduced ABN activity. Optogenetic silencing of this sparse ABN activity during REM sleep alters the structural remodeling of spines on ABN dendrites and impairs memory consolidation. These findings provide a causal link between ABN activity during REM sleep and memory consolidation.


Assuntos
Condicionamento Psicológico , Giro Denteado/fisiologia , Consolidação da Memória/fisiologia , Neurônios/fisiologia , Sono REM/fisiologia , Animais , Cálcio/metabolismo , Giro Denteado/citologia , Eletroencefalografia , Eletromiografia , Medo , Hipocampo , Aprendizagem , Camundongos , Neurogênese , Optogenética , Ritmo Teta
6.
Neuron ; 107(3): 509-521.e7, 2020 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-32492366

RESUMO

Post-tetanic potentiation (PTP) is an attractive candidate mechanism for hippocampus-dependent short-term memory. Although PTP has a uniquely large magnitude at hippocampal mossy fiber-CA3 pyramidal neuron synapses, it is unclear whether it can be induced by natural activity and whether its lifetime is sufficient to support short-term memory. We combined in vivo recordings from granule cells (GCs), in vitro paired recordings from mossy fiber terminals and postsynaptic CA3 neurons, and "flash and freeze" electron microscopy. PTP was induced at single synapses and showed a low induction threshold adapted to sparse GC activity in vivo. PTP was mainly generated by enlargement of the readily releasable pool of synaptic vesicles, allowing multiplicative interaction with other plasticity forms. PTP was associated with an increase in the docked vesicle pool, suggesting formation of structural "pool engrams." Absence of presynaptic activity extended the lifetime of the potentiation, enabling prolonged information storage in the hippocampal network.


Assuntos
Memória de Curto Prazo/fisiologia , Fibras Musgosas Hipocampais/metabolismo , Plasticidade Neuronal/fisiologia , Células Piramidais/metabolismo , Sinapses/metabolismo , Vesículas Sinápticas/metabolismo , Potenciais de Ação/fisiologia , Animais , Região CA3 Hipocampal/citologia , Giro Denteado/citologia , Camundongos , Microscopia Eletrônica , Fibras Musgosas Hipocampais/fisiologia , Fibras Musgosas Hipocampais/ultraestrutura , Técnicas de Patch-Clamp , Células Piramidais/fisiologia , Células Piramidais/ultraestrutura , Ratos , Sinapses/fisiologia , Potenciais Sinápticos/fisiologia
7.
PLoS One ; 15(5): e0232241, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32407421

RESUMO

Under physiologic conditions, the dentate gyrus (DG) exhibits exceptionally low levels of activity compared to other brain regions. A sparse activation pattern is observed even when the DG is engaged to process new information; for example, only ~1-3% of neurons in the DG granule cell layer (GCL) are activated after placing animals in a novel, enriched environment. Moreover, such physiologic stimulation of GCL neurons recruits young granule cells more readily than older cells. This sparse pattern of cell activation has largely been attributed to intrinsic circuit properties of the DG, such as reduced threshold for activation in younger cells, and increased inhibition onto older cells. Given these intrinsic properties, we asked whether such activation of young granule cells was unique to physiologic stimulation, or could be elicited by general pharmacological activation of the hippocampus. We found that administration of kainic acid (KA) at a low dose (5 mg/kg) to wildtype C57BL/6 mice activated a similarly sparse number of cells in the GCL as physiologic DG stimulation by exposure to a novel, enriched environment. However, unlike physiologic stimulation, 5 mg/kg KA activated primarily old granule cells as well as GABAergic interneurons. This finding indicates that intrinsic circuit properties of the DG alone may not be sufficient to support the engagement of young granule cells, and suggest that other factors such as the specificity of the pattern of inputs, may be involved.


Assuntos
Giro Denteado/citologia , Animais , Giro Denteado/efeitos dos fármacos , Giro Denteado/fisiologia , Relação Dose-Resposta a Droga , Eletroencefalografia , Feminino , Ácido Caínico/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/citologia , Neurônios/efeitos dos fármacos
8.
Ecotoxicol Environ Saf ; 200: 110733, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32450442

RESUMO

Paraquat (1,1'-dimethyl-4,4'-bipyridium dichloride, PQ), a non-selective and efficient herbicide, causes neuroinflammation, neurodegeneration and memory dysfunction. However, adverse effects of PQ on the neuroimmune interactions have rarely been investigated. Female adult C57/BL6 mice were divided into 3 groups and treated with PQ (intraperitoneal injection, 1 mg/kg or 5 mg/kg) or the vehicle (an equivalent volume of 0.9% saline) every two days, at day 1, 3, 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, for a total of 14 doses. We evaluated blood-brain barrier (BBB) integrity and PQ concentrations during the course of PQ exposure and tested interleukin-1ß (IL-1ß) concentrations in dentate gyrus (DG) after 28 days PQ exposure. In addition, memory function, neural stem cells (NSCs) proliferation, neurogenesis and microglia polarization were analyzed after PQ exposure. Furthermore, mice were intraperitoneal injections of anti-IL-1ß during 5 mg/kg PQ exposure to test the rule of IL-1ß. Blood-brain barrier (BBB) permeability and PQ concentrations increased gradually during PQ exposure (n = 6). Moreover, memory function, NSCs proliferation and neurogenesis were impaired after 5 mg/kg PQ exposure (n = 6). Further analyses revealed that 'classically' activated (M1) microglia and IL-1ß concentrations in DG were increased after 5 mg/kg PQ treatment (n = 6). Moreover, we found that neutralization of IL-1ß partly restored PQ-induced NSCs impairments and memory dysfunction (n = 6). In conclusion, our results revealed that PQ induced NSCs impairments and memory dysfunction in adult mice, which was related to the release of IL-1ß by M1-polarized microglia in DG. These findings may help understand the neurotoxic effect of PQ.


Assuntos
Giro Denteado/efeitos dos fármacos , Herbicidas/toxicidade , Interleucina-1beta/metabolismo , Neurogênese/efeitos dos fármacos , Paraquat/toxicidade , Animais , Barreira Hematoencefálica/efeitos dos fármacos , Giro Denteado/citologia , Feminino , Memória/efeitos dos fármacos , Camundongos Endogâmicos C57BL , Microglia/efeitos dos fármacos , Células-Tronco Neurais/citologia , Células-Tronco Neurais/efeitos dos fármacos
9.
Life Sci ; 254: 117755, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32437792

RESUMO

AIMS: Efficient memory formation in rodents depends on adult neurogenesis in the subgranular zone of the hippocampus, and mounting evidence suggests that deficiencies in initiating repair of oxidatively induced DNA damage may impair neurogenesis. Hence, we aimed to determine whether loss of the DNA glycosylase, endonuclease VIII-like 1 (Neil1), affects hippocampal neurogenesis and memory performance in young-adult mice. MAIN METHODS: Eight-week-old male wild-type and Neil1-deficient (Neil1-/-) mice were treated with bromodeoxyuridine to track neuronal proliferation and differentiation. A neurosphere formation assay was further used to measure neuroprogenitor proliferative capacity. Hippocampus-related memory functions were assessed with Y-maze spontaneous alternation and novel object recognition tests. KEY FINDINGS: Young-adult male Neil1-/- mice exhibited diminished adult hippocampal neurogenesis in the dentate gyrus, probably as a result of poor survival of newly proliferated neurons. Furthermore, the Y-maze spontaneous alternation and novel object recognition tests respectively revealed that Neil1 deficiency impairs spatial and non-spatial hippocampus-related memory functions. We also found that expression of p53, a central regulator of apoptosis, was upregulated in the dentate gyrus of Neil1-/- mice, while the level of ß-catenin, a key cell survival molecule, was downregulated. SIGNIFICANCE: The DNA glycosylase, Neil1, promotes successful hippocampal neurogenesis and learning and memory in young-adult mice.


Assuntos
Cognição/fisiologia , DNA Glicosilases/deficiência , Hipocampo/enzimologia , Memória/fisiologia , Neurônios/enzimologia , Animais , Diferenciação Celular/fisiologia , Sobrevivência Celular/fisiologia , Disfunção Cognitiva/enzimologia , Disfunção Cognitiva/patologia , DNA Glicosilases/genética , DNA Glicosilases/metabolismo , Giro Denteado/citologia , Giro Denteado/enzimologia , Hipocampo/citologia , Hipocampo/metabolismo , Aprendizagem/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neurogênese/fisiologia , Neurônios/citologia
10.
J Neurosci ; 40(18): 3576-3590, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32234778

RESUMO

Theoretical models and experimental evidence have suggested that connections from the dentate gyrus (DG) to CA3 play important roles in representing orthogonal information (i.e., pattern separation) in the hippocampus. However, the effects of eliminating the DG on neural firing patterns in the CA3 have rarely been tested in a goal-directed memory task that requires both the DG and CA3. In this study, selective lesions in the DG were made using colchicine in male Long-Evans rats, and single units from the CA3 were recorded as the rats performed visual scene memory tasks. The original scenes used in training were altered during testing by blurring to varying degrees or by using visual masks, resulting in maximal recruitment of the DG-CA3 circuits. Compared with controls, the performance of rats with DG lesions was particularly impaired when blurred scenes were used in the task. In addition, the firing rate modulation associated with visual scenes in these rats was significantly reduced in the single units recorded from the CA3 when ambiguous scenes were presented, largely because DG-deprived CA3 cells did not show stepwise, categorical rate changes across varying degrees of scene ambiguity compared with controls. These findings suggest that the DG plays key roles not only during the acquisition of scene memories but also during retrieval when modified visual scenes are processed in conjunction with the CA3 by making the CA3 network respond orthogonally to ambiguous scenes.SIGNIFICANCE STATEMENT Despite the behavioral evidence supporting the role of the dentate gyrus in pattern separation in the hippocampus, the underlying neural mechanisms are largely unknown. By recording single units from the CA3 in DG-lesioned rats performing a visual scene memory task, we report that the scene-related modulation of neural firing was significantly reduced in the DG-lesion rats compared with controls, especially when the original scene stimuli were ambiguously altered. Our findings suggest that the dentate gyrus plays an essential role during memory retrieval and performs a critical computation to make categorical rate modulation occur in the CA3 between different scenes, especially when ambiguity is present in the environment.


Assuntos
Região CA3 Hipocampal/fisiologia , Giro Denteado/fisiologia , Memória/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Estimulação Luminosa/métodos , Animais , Região CA3 Hipocampal/citologia , Giro Denteado/citologia , Masculino , Aprendizagem em Labirinto/fisiologia , Ratos , Ratos Long-Evans
11.
J Pharmacol Sci ; 143(2): 97-105, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32173264

RESUMO

Folate deficiency has been suggested as a risk factor for depression in preclinical and clinical studies. Several hypotheses of mechanisms underlying folate deficiency-induced depressive symptoms have been proposed, but the detailed mechanisms are still unclear. In this study, we assessed whether post-weaning folate deficiency affect neurological and psychological function. The low folate diet-fed mice showed depression-like behavior in the forced swim test. In contrast, spontaneous locomotor activity, social behavior, coordinated motor skills, anxiety-like behavior and spatial memory did not differ between control and low folate diet-fed mice. In the dentate gyrus (DG) of the hippocampus, decreased number of newborn mature neurons and increased number of immature neurons were observed in low folate diet-fed mice. Staining with Golgi-Cox method revealed that dendritic complexity, spine density and the number of mature spines of neurons were markedly reduced in the DG of low folate diet-fed mice. Stress response of neurons indicated as c-Fos expression was also reduced in the DG of low folate diet-fed mice. These results suggest that reduction in the degree of maturation of newborn hippocampal neurons underlies folate deficiency-induced depressive symptoms.


Assuntos
Giro Denteado/citologia , Giro Denteado/patologia , Depressão/etiologia , Depressão/patologia , Deficiência de Ácido Fólico/complicações , Neurônios/patologia , Desmame , Animais , Expressão Gênica , Masculino , Camundongos Endogâmicos , Neurônios/metabolismo , Proteínas Proto-Oncogênicas c-fos/genética , Proteínas Proto-Oncogênicas c-fos/metabolismo
12.
Ann Neurol ; 87(4): 497-515, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32031699

RESUMO

OBJECTIVE: Traumatic brain injury is a major risk factor for acquired epilepsies, and understanding the mechanisms underlying the early pathophysiology could yield viable therapeutic targets. Growing evidence indicates a role for inflammatory signaling in modifying neuronal excitability and promoting epileptogenesis. Here we examined the effect of innate immune receptor Toll-like receptor 4 (TLR4) on excitability of the hippocampal dentate gyrus and epileptogenesis after brain injury. METHODS: Slice and in vivo electrophysiology and Western blots were conducted in rats subject to fluid percussion brain injury or sham injury. RESULTS: The studies identify that TLR4 signaling in neurons augments dentate granule cell calcium-permeable α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor (CP-AMPAR) currents after brain injury. Blocking TLR4 signaling in vivo shortly after brain injury reduced dentate network excitability and seizure susceptibility. When blocking of TLR4 signaling after injury was delayed, however, this treatment failed to reduce postinjury seizure susceptibility. Furthermore, TLR4 signal blocking was less efficacious in limiting seizure susceptibility when AMPAR currents, downstream targets of TLR4 signaling, were transiently enhanced. Paradoxically, blocking TLR4 signaling augmented both network excitability and seizure susceptibility in uninjured controls. Despite the differential effect on seizure susceptibility, TLR4 antagonism suppressed cellular inflammatory responses after injury without impacting sham controls. INTERPRETATION: These findings demonstrate that independently of glia, the immune receptor TLR4 directly regulates post-traumatic neuronal excitability. Moreover, the TLR4-dependent early increase in dentate excitability is causally associated with epileptogenesis. Identification and selective targeting of the mechanisms underlying the aberrant TLR4-mediated increase in CP-AMPAR signaling after injury may prevent epileptogenesis after brain trauma. ANN NEUROL 2020;87:497-515.


Assuntos
Lesões Encefálicas Traumáticas/metabolismo , Giro Denteado/metabolismo , Epilepsia/metabolismo , Neurônios/metabolismo , Receptores de AMPA/metabolismo , Receptor 4 Toll-Like/metabolismo , Animais , Western Blotting , Lesões Encefálicas Traumáticas/complicações , Lesões Encefálicas Traumáticas/fisiopatologia , Cálcio/metabolismo , Giro Denteado/citologia , Eletroencefalografia , Epilepsia/etiologia , Epilepsia/fisiopatologia , Hipocampo/citologia , Hipocampo/metabolismo , Masculino , Técnicas de Patch-Clamp , Cultura Primária de Células , Ratos , Sulfonamidas/farmacologia , Receptor 4 Toll-Like/antagonistas & inibidores
13.
J Neurosci ; 40(11): 2200-2214, 2020 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-32047055

RESUMO

The dentate gyrus (DG) in the hippocampus may play key roles in remembering distinct episodes through pattern separation, which may be subserved by the sparse firing properties of granule cells (GCs) in the DG. Low intrinsic excitability is characteristic of mature GCs, but ion channel mechanisms are not fully understood. Here, we investigated ionic channel mechanisms for firing frequency regulation in hippocampal GCs using male and female mice, and identified Kv4.1 as a key player. Immunofluorescence analysis showed that Kv4.1 was preferentially expressed in the DG, and its expression level determined by Western blot analysis was higher at 8-week than 3-week-old mice, suggesting a developmental regulation of Kv4.1 expression. With respect to firing frequency, GCs are categorized into two distinctive groups: low-frequency (LF) and high-frequency (HF) firing GCs. Input resistance (R in) of most LF-GCs is lower than 200 MΩ, suggesting that LF-GCs are fully mature GCs. Kv4.1 channel inhibition by intracellular perfusion of Kv4.1 antibody increased firing rates and gain of the input-output relationship selectively in LF-GCs with no significant effect on resting membrane potential and R in, but had no effect in HF-GCs. Importantly, mature GCs from mice depleted of Kv4.1 transcripts in the DG showed increased firing frequency, and these mice showed an impairment in contextual discrimination task. Our findings suggest that Kv4.1 expression occurring at late stage of GC maturation is essential for low excitability of DG networks and thereby contributes to pattern separation.SIGNIFICANCE STATEMENT The sparse activity of dentate granule cells (GCs), which is essential for pattern separation, is supported by high inhibitory inputs and low intrinsic excitability of GCs. Low excitability of GCs is thought to be attributable to a high K+ conductance at resting membrane potentials, but this study identifies Kv4.1, a depolarization-activated K+ channel, as a key ion channel that regulates firing of GCs without affecting resting membrane potentials. Kv4.1 expression is developmentally regulated and Kv4.1 currents are detected only in mature GCs that show low-frequency firing, but not in less mature high-frequency firing GCs. Furthermore, mice depleted of Kv4.1 transcripts in the dentate gyrus show impaired pattern separation, suggesting that Kv4.1 is crucial for sparse coding and pattern separation.


Assuntos
Aprendizagem da Esquiva/fisiologia , Giro Denteado/citologia , Discriminação Psicológica/fisiologia , Neurônios/fisiologia , Canais de Potássio Shal/fisiologia , Potenciais de Ação , Animais , Região CA1 Hipocampal/citologia , Região CA1 Hipocampal/fisiologia , Condicionamento Clássico , Giro Denteado/fisiologia , Eletrochoque , Feminino , Reação de Congelamento Cataléptica/fisiologia , Regulação da Expressão Gênica no Desenvolvimento , Técnicas de Introdução de Genes , Genes Reporter , Humanos , Masculino , Aprendizagem em Labirinto , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/classificação , Técnicas de Patch-Clamp , Células Piramidais/fisiologia , Interferência de RNA , RNA Mensageiro/antagonistas & inibidores , RNA Mensageiro/genética , RNA Interferente Pequeno/farmacologia , Canais de Potássio Shal/biossíntese , Canais de Potássio Shal/genética , Organismos Livres de Patógenos Específicos
14.
Nature ; 577(7791): 531-536, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31942070

RESUMO

The hippocampus is an important part of the limbic system in the human brain that has essential roles in spatial navigation and the consolidation of information from short-term memory to long-term memory1,2. Here we use single-cell RNA sequencing and assay for transposase-accessible chromatin using sequencing (ATAC-seq) analysis to illustrate the cell types, cell linage, molecular features and transcriptional regulation of the developing human hippocampus. Using the transcriptomes of 30,416 cells from the human hippocampus at gestational weeks 16-27, we identify 47 cell subtypes and their developmental trajectories. We also identify the migrating paths and cell lineages of PAX6+ and HOPX+ hippocampal progenitors, and regional markers of CA1, CA3 and dentate gyrus neurons. Multiomic data have uncovered transcriptional regulatory networks of the dentate gyrus marker PROX1. We also illustrate spatially specific gene expression in the developing human prefrontal cortex and hippocampus. The molecular features of the human hippocampus at gestational weeks 16-20 are similar to those of the mouse at postnatal days 0-5 and reveal gene expression differences between the two species. Transient expression of the primate-specific gene NBPF1 leads to a marked increase in PROX1+ cells in the mouse hippocampus. These data provides a blueprint for understanding human hippocampal development and a tool for investigating related diseases.


Assuntos
Linhagem da Célula , Regulação da Expressão Gênica no Desenvolvimento/genética , Hipocampo/citologia , Hipocampo/embriologia , Animais , Proteínas de Transporte/metabolismo , Giro Denteado/citologia , Giro Denteado/embriologia , Giro Denteado/metabolismo , Evolução Molecular , Feminino , Hipocampo/metabolismo , Proteínas de Homeodomínio/metabolismo , Humanos , Masculino , Camundongos , Células-Tronco Neurais/citologia , Células-Tronco Neurais/metabolismo , Neurogênese , Neurônios/citologia , Neurônios/metabolismo , Fator de Transcrição PAX6/metabolismo , Córtex Pré-Frontal/citologia , Córtex Pré-Frontal/embriologia , Córtex Pré-Frontal/metabolismo , Especificidade da Espécie , Transcriptoma/genética , Proteínas Supressoras de Tumor/metabolismo
15.
J Med Food ; 23(2): 198-202, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31913760

RESUMO

Temporal lobe epilepsy (TLE) is the most common form of localization-related epilepsy, with the highest prevalence rate in adulthood. Recently, we reported the beneficial effects of the individual treatment with flavonoids such as silibinin and morin in kainic acid (KA)-treated mouse model for TLE. In this study, we investigated whether there is a synergistic effect of co-treatment with silibinin and morin on the susceptibility to seizure, the frequency of spontaneous recurrent seizures (SRSs), and granule cell dispersion in the dentate gyrus, which could be partially controlled by treatment with each flavonoid in the animal model for TLE. Unfortunately, we did not observe any synergistic effect against the susceptibility of seizure and SRS induced by KA treatment. However, the combination of these flavonoids showed similar antiepileptic effects compared with treatment with each one individually. Therefore, although silibinin and morin are not suitable for combination therapy, our results still suggest that these flavonoids can be used as potent therapeutic compounds for preventing epileptic seizures.


Assuntos
Epilepsia do Lobo Temporal/tratamento farmacológico , Flavonoides/uso terapêutico , Convulsões/tratamento farmacológico , Silibina/uso terapêutico , Animais , Giro Denteado/citologia , Giro Denteado/efeitos dos fármacos , Sinergismo Farmacológico , Epilepsia do Lobo Temporal/induzido quimicamente , Ácido Caínico , Camundongos , Convulsões/induzido quimicamente
16.
Cell Rep ; 30(4): 959-968.e3, 2020 01 28.
Artigo em Inglês | MEDLINE | ID: mdl-31995766

RESUMO

In the adult brain, new dentate granule cells integrate into neural circuits and participate in hippocampal functioning. However, when and how they initiate this integration remain poorly understood. Using retroviral and live-imaging methods, we find that new neurons undergo neurite remodeling for competitive horizontal-to-radial repositioning in the dentate gyrus prior to circuit integration. Gene expression profiling, lipidomics analysis, and molecular interrogation of new neurons during this period reveal a rapid activation of sphingolipid signaling mediated by sphingosine-1-phosphate receptor 1. Genetic manipulation of this G protein-coupled receptor reveals its requirement for successful repositioning of new neurons. This receptor is also activated by hippocampus-engaged behaviors, which enhances repositioning efficiency. These findings reveal that activity-dependent sphingolipid signaling regulates cellular repositioning of new dentate granule cells. The competitive horizontal-to-radial repositioning of new neurons may provide a gating strategy in the adult brain to limit the integration of new neurons into pre-existing circuits.


Assuntos
Giro Denteado/metabolismo , Hipocampo/metabolismo , Neurogênese/genética , Neurônios/metabolismo , Esfingolipídeos/metabolismo , Receptores de Esfingosina-1-Fosfato/metabolismo , Animais , Giro Denteado/citologia , Giro Denteado/crescimento & desenvolvimento , Giro Denteado/fisiologia , Feminino , Técnicas de Silenciamento de Genes , Hipocampo/citologia , Hipocampo/crescimento & desenvolvimento , Hipocampo/fisiologia , Lipidômica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neurogênese/fisiologia , Neurônios/fisiologia , RNA-Seq , Transdução de Sinais/genética , Transdução de Sinais/fisiologia , Esfingolipídeos/genética , Receptores de Esfingosina-1-Fosfato/genética
17.
Anat Histol Embryol ; 49(1): 3-16, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31568602

RESUMO

Earlier observations in neuroscience suggested that no new neurons form in the mature central nervous system. Evidence now indicates that new neurons do form in the adult mammalian brain. Two regions of the mature mammalian brain generate new neurons: (a) the border of the lateral ventricles of the brain (subventricular zone) and (b) the subgranular zone (SGZ) of the dentate gyrus of the hippocampus. This review focuses only on new neuron formation in the dentate gyrus of the hippocampus. During normal prenatal and early postnatal development, neural stem cells (NSCs) give rise to differentiated neurons. NSCs persist in the dentate gyrus SGZ, undergoing cell division, with some daughter cells differentiating into functional neurons that participate in learning and memory and general cognition through integration into pre-existing neural networks. Axons, which emanate from neurons in the entorhinal cortex, synapse with dendrites of the granule cells (small neurons) of the dentate gyrus. Axons from granule cells synapse with pyramidal cells in the hippocampal CA3 region, which send axons to synapse with CA1 hippocampal pyramidal cells that send their axons out of the hippocampus proper. Adult neurogenesis includes proliferation, differentiation, migration, the death of some newly formed cells and final integration of surviving cells into neural networks. We summarise these processes in adult mammalian hippocampal neurogenesis and discuss the roles of major signalling molecules that influence neurogenesis, including neurotransmitters and some hormones. The recent controversy raised concerning whether or not adult neurogenesis occurs in humans also is discussed.


Assuntos
Giro Denteado/citologia , Células-Tronco Neurais/citologia , Neurogênese , Adulto , Animais , Astrócitos/metabolismo , Diferenciação Celular , Proliferação de Células , Microambiente Celular/fisiologia , Epigenômica , Hipocampo/citologia , Hormônios , Humanos , Ventrículos Laterais/citologia , Mamíferos/anatomia & histologia , Memória , Neurogênese/fisiologia , Neurônios/citologia , Transdução de Sinais
18.
Nat Commun ; 10(1): 5561, 2019 12 05.
Artigo em Inglês | MEDLINE | ID: mdl-31804491

RESUMO

Fast-spiking parvalbumin-expressing interneurons (PVIs) and granule cells (GCs) of the dentate gyrus receive layer-specific dendritic inhibition. Its impact on PVI and GC excitability is, however, unknown. By applying whole-cell recordings, GABA uncaging and single-cell-modeling, we show that proximal dendritic inhibition in PVIs is less efficient in lowering perforant path-mediated subthreshold depolarization than distal inhibition but both are highly efficient in silencing PVIs. These inhibitory effects can be explained by proximal shunting and distal strong hyperpolarizing inhibition. In contrast, GC proximal but not distal inhibition is the primary regulator of their excitability and recruitment. In GCs inhibition is hyperpolarizing along the entire somato-dendritic axis with similar strength. Thus, dendritic inhibition differentially controls input-output transformations in PVIs and GCs. Dendritic inhibition in PVIs is suited to balance PVI discharges in dependence on global network activity thereby providing strong and tuned perisomatic inhibition that contributes to the sparse representation of information in GC assemblies.


Assuntos
Dendritos/fisiologia , Giro Denteado/fisiologia , Potenciais Pós-Sinápticos Excitadores/fisiologia , Interneurônios/fisiologia , Inibição Neural/fisiologia , Neurônios/fisiologia , Parvalbuminas/metabolismo , Potenciais de Ação/fisiologia , Animais , Giro Denteado/citologia , Giro Denteado/metabolismo , Feminino , Interneurônios/citologia , Interneurônios/metabolismo , Masculino , Rede Nervosa/citologia , Rede Nervosa/metabolismo , Rede Nervosa/fisiologia , Neurônios/citologia , Neurônios/metabolismo , Técnicas de Patch-Clamp , Ratos Wistar
19.
Sci Rep ; 9(1): 18038, 2019 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-31792338

RESUMO

Understanding the sequence of events from undifferentiated stem cells to neuron is not only important for the basic knowledge of stem cell biology, but also for therapeutic applications. In this study we examined the sequence of biological events during neural differentiation of human periodontal ligament stem cells (hPDLSCs). Here, we show that hPDLSCs-derived neural-like cells display a sequence of morphologic development highly similar to those reported before in primary neuronal cultures derived from rodent brains. We observed that cell proliferation is not present through neurogenesis from hPDLSCs. Futhermore, we may have discovered micronuclei movement and transient cell nuclei lobulation coincident to in vitro neurogenesis. Morphological analysis also reveals that neurogenic niches in the adult mouse brain contain cells with nuclear shapes highly similar to those observed during in vitro neurogenesis from hPDLSCs. Our results provide additional evidence that it is possible to differentiate hPDLSCs to neuron-like cells and suggest the possibility that the sequence of events from stem cell to neuron does not necessarily requires cell division from stem cell.


Assuntos
Diferenciação Celular , Neurogênese , Neurônios/fisiologia , Ligamento Periodontal/citologia , Células-Tronco/fisiologia , Animais , Núcleo Celular/ultraestrutura , Proliferação de Células , Giro Denteado/citologia , Giro Denteado/crescimento & desenvolvimento , Humanos , Ventrículos Laterais/citologia , Ventrículos Laterais/crescimento & desenvolvimento , Camundongos , Microscopia Eletrônica de Transmissão , Neurônios/citologia , Cultura Primária de Células , Esferoides Celulares/fisiologia , Nicho de Células-Tronco , Células-Tronco/citologia
20.
J Neurosci ; 39(48): 9570-9584, 2019 11 27.
Artigo em Inglês | MEDLINE | ID: mdl-31641051

RESUMO

The complementary processes of pattern completion and pattern separation are thought to be essential for successful memory storage and recall. The dentate gyrus (DG) and proximal CA3 (pCA3) regions have been implicated in pattern separation, in part through extracellular recording studies of these areas. However, the DG contains two types of excitatory cells: granule cells of the granule layer and mossy cells of the hilus. Little is known about the firing properties of mossy cells in freely moving animals, and it is unclear how their activity may contribute to the mnemonic functions of the hippocampus. Furthermore, tetrodes in the dentate granule layer and pCA3 pyramidal layer can also record mossy cells, thus introducing ambiguity into the identification of cell types recorded. Using a random forests classifier, we classified cells recorded in DG (Neunuebel and Knierim, 2014) and pCA3 (Lee et al., 2015) of 16 male rats and separately examined the responses of granule cells, mossy cells, and pCA3 pyramidal cells in a local/global cue mismatch task. All three cell types displayed low correlations between the population representations of the rat's position in the standard and cue-mismatch sessions. These results suggest that all three excitatory cell types within the DG/pCA3 circuit may act as a single functional unit to support pattern separation.SIGNIFICANCE STATEMENT Mossy cells in the dentate gyrus (DG) are an integral component of the DG/pCA3 circuit. While the role of granule cells in the circuitry and computations of the hippocampus has been a focus of study for decades, the contributions of mossy cells have been largely overlooked. Recent studies have revealed the spatial firing properties of mossy cells in awake behaving animals, but how the activity of these highly active cells contributes to the mnemonic functions of the DG is uncertain. We separately analyzed mossy cells, granule cells, and pCA3 cells and found that all three cell types respond similarly to a local/global cue mismatch, suggesting that they form a single functional unit supporting pattern separation.


Assuntos
Região CA3 Hipocampal/citologia , Região CA3 Hipocampal/fisiologia , Fibras Musgosas Hipocampais/fisiologia , Células Piramidais/fisiologia , Animais , Giro Denteado/citologia , Giro Denteado/fisiologia , Masculino , Distribuição Aleatória , Ratos , Ratos Long-Evans
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