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1.
Proc Natl Acad Sci U S A ; 120(38): e2301003120, 2023 09 19.
Artigo em Inglês | MEDLINE | ID: mdl-37695902

RESUMO

Clustered protocadherin (Pcdh) functions as a cell recognition molecule through the homophilic interaction in the central nervous system. However, its interactions have not yet been visualized in neurons. We previously reported PcdhγB2-Förster resonance energy transfer (FRET) probes to be applicable only to cell lines. Herein, we designed γB2-FRET probes by fusing FRET donor and acceptor fluorescent proteins to a single γB2 molecule and succeeded in visualizing γB2 homophilic interaction in cultured hippocampal neurons. The γB2-FRET probe localized in the soma and neurites, and FRET signals, which were observed at contact sites between neurites, eliminated by ethylene glycol tetraacetic acid (EGTA) addition. Live imaging revealed that the FRET-negative γB2 signals rapidly moved along neurites and soma, whereas the FRET-positive signals remained in place. We observed that the γB2 proteins at synapses rarely interact homophilically. The γB2-FRET probe might allow us to elucidate the function of the homophilic interaction and the cell recognition mechanism.


Assuntos
Neurônios , Protocaderinas , Neuritos , Corpo Celular , Comunicação Celular
2.
J Neuroinflammation ; 21(1): 114, 2024 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-38698428

RESUMO

Maternal immunoglobulin (Ig)G is present in breast milk and has been shown to contribute to the development of the immune system in infants. In contrast, maternal IgG has no known effect on early childhood brain development. We found maternal IgG immunoreactivity in microglia, which are resident macrophages of the central nervous system of the pup brain, peaking at postnatal one week. Strong IgG immunoreactivity was observed in microglia in the corpus callosum and cerebellar white matter. IgG stimulation of primary cultured microglia activated the type I interferon feedback loop by Syk. Analysis of neonatal Fc receptor knockout (FcRn KO) mice that could not take up IgG from their mothers revealed abnormalities in the proliferation and/or survival of microglia, oligodendrocytes, and some types of interneurons. Moreover, FcRn KO mice also exhibited abnormalities in social behavior and lower locomotor activity in their home cages. Thus, changes in the mother-derived IgG levels affect brain development in offsprings.


Assuntos
Animais Recém-Nascidos , Encéfalo , Imunoglobulina G , Camundongos Knockout , Animais , Camundongos , Encéfalo/crescimento & desenvolvimento , Encéfalo/metabolismo , Feminino , Camundongos Endogâmicos C57BL , Gravidez , Células Cultivadas , Microglia/metabolismo , Receptores Fc/metabolismo , Receptores Fc/genética
3.
Analyst ; 148(10): 2237-2244, 2023 May 16.
Artigo em Inglês | MEDLINE | ID: mdl-37066865

RESUMO

Enzymes are used to amplify signals for detection of antigen proteins in biological samples. However, the enzymes conventionally used for this purpose have limitations, such as the presence of the same (i.e., endogenous) activity in human cells and difficulty in simultaneous use of multiple enzymes because of differences in their required reaction conditions. In this report, we identify an enzyme that can overcome these problems: ß-D-galacturonidase (GalUAase) from Eisenbergiella tayi. GalUAase activity was confirmed to be absent from human cells. The substrate of GalUAase, galacturonic acid, is highly hydrophilic because of its anionic carboxylate group; high substrate hydrophilicity is an ideal characteristic for the substrate of an enzyme used for detection because it decreases nonspecific adsorption to biological samples. We show that E. tayi GalUAase could be used in the detection of antigen proteins on live human cells with lower background signal than the conventionally used enzyme ß-D-galactosidase. The combinatorial use of GalUAase with ß-D-galactosidase enabled simultaneous detection of two antigens on live cells.


Assuntos
Antígenos , Humanos , beta-Galactosidase/metabolismo
4.
Cereb Cortex ; 33(1): 50-67, 2022 12 15.
Artigo em Inglês | MEDLINE | ID: mdl-35396593

RESUMO

Feedback projections from the secondary motor cortex (M2) to the primary motor and sensory cortices are essential for behavior selection and sensory perception. Intratelencephalic (IT) cells in layer 5 (L5) contribute feedback projections to diverse cortical areas. Here we show that L5 IT cells participating in feedback connections to layer 1 (L1) exhibit distinct projection patterns, genetic profiles, and electrophysiological properties relative to other L5 IT cells. An analysis of the MouseLight database found that L5 IT cells preferentially targeting L1 project broadly to more cortical regions, including the perirhinal and auditory cortices, and innervate a larger volume of striatum than the other L5 IT cells. We found experimentally that in upper L5 (L5a), ER81 (ETV1) was found more often in L1-preferring IT cells, and in IT cells projecting to perirhinal/auditory regions than those projecting to primary motor or somatosensory regions. The perirhinal region-projecting L5a IT cells were synaptically connected to each other and displayed lower input resistance than contra-M2 projecting IT cells including L1-preferring and nonpreferring cells. Our findings suggest that M2-L5a IT L1-preferring cells exhibit stronger ER81 expression and broader cortical/striatal projection fields than do cells that do not preferentially target L1.


Assuntos
Córtex Motor , Camundongos , Animais , Córtex Motor/fisiologia , Lobo Parietal , Fenômenos Eletrofisiológicos , Corpo Estriado , Vias Neurais/fisiologia
5.
J Pathol ; 255(4): 362-373, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34370295

RESUMO

Urinary fatty acid binding protein 1 (FABP1, also known as liver-type FABP) has been implicated as a biomarker of acute kidney injury (AKI) in humans. However, the precise biological mechanisms underlying its elevation remain elusive. Here, we show that urinary FABP1 primarily reflects impaired protein reabsorption in proximal tubule epithelial cells (PTECs). Bilateral nephrectomy resulted in a marked increase in serum FABP1 levels, suggesting that the kidney is an essential organ for removing serum FABP1. Injected recombinant FABP1 was filtered through the glomeruli and robustly reabsorbed via the apical membrane of PTECs. Urinary FABP1 was significantly elevated in mice devoid of megalin, a giant endocytic receptor for protein reabsorption. Elevation of urinary FABP1 was also observed in patients with Dent disease, a rare genetic disease characterized by defective megalin function in PTECs. Urinary FABP1 levels were exponentially increased following acetaminophen overdose, with both nephrotoxicity and hepatotoxicity observed. FABP1-deficient mice with liver-specific overexpression of FABP1 showed a massive increase in urinary FABP1 levels upon acetaminophen injection, indicating that urinary FABP1 is liver-derived. Lastly, we employed transgenic mice expressing diphtheria toxin receptor (DT-R) either in a hepatocyte- or in a PTEC-specific manner, or both. Upon administration of diphtheria toxin (DT), massive excretion of urinary FABP1 was induced in mice with both kidney and liver injury, while mice with either injury type showed marginal excretion. Collectively, our data demonstrated that intact PTECs have a considerable capacity to reabsorb liver-derived FABP1 through a megalin-mediated mechanism. Thus, urinary FABP1, which is synergistically enhanced by concurrent liver injury, is a biomarker for impaired protein reabsorption in AKI. These findings address the use of urinary FABP1 as a biomarker of histologically injured PTECs that secrete FABP1 into primary urine, and suggest the use of this biomarker to simultaneously monitor impaired tubular reabsorption and liver function. © 2021 The Authors. The Journal of Pathology published by John Wiley & Sons, Ltd. on behalf of The Pathological Society of Great Britain and Ireland.


Assuntos
Injúria Renal Aguda , Biomarcadores/urina , Proteínas de Ligação a Ácido Graxo/urina , Hepatopatias , Animais , Humanos , Camundongos
6.
Pflugers Arch ; 473(12): 1911-1924, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34724104

RESUMO

The nucleus accumbens (NAc) receives cortical projections principally from the insular cortex (IC) and medial prefrontal cortex (mPFC). Among NAc neurons, cholinergic interneurons (ChNs) regulate the activities of medium spiny neurons (MSNs), which make up ~ 95% of NAc neurons, by modulating their firing and synaptic properties. However, little is known about the synaptic mechanisms, including their cell-type-dependent corticoaccumbal projection properties and cholinergic effects on the NAc core. Here, we performed whole-cell patch-clamp recordings from NAc MSNs and ChNs in acute brain slice preparations obtained from rats that received an AAV5-hSyn-ChR2(H134R)-mCherry injection into the IC or mPFC. Light stimulation of IC or mPFC axons induced comparable phase-locked excitatory postsynaptic currents (EPSCs) in MSNs. On the other hand, ChNs showed consistent EPSCs evoked by light stimulation of mPFC axons, whereas light stimulation of IC axons evoked much smaller EPSCs, which often showed failure in ChNs. Light-evoked EPSCs were abolished by tetrodotoxin and were recovered by 4-aminopyridine, suggesting that corticoaccumbal projections monosynaptically induce EPSCs in MSNs and ChNs. Carbachol effectively suppressed the amplitude of EPSCs in MSNs and ChNs evoked by light stimulation of IC or mPFC axons and in ChNs evoked by stimulating mPFC axons. The carbachol-induced suppression was recovered by atropine or pirenzepine, while preapplication of gallamine, J104129, PD102807, or AF-DX384 did not block the carbachol-induced EPSC suppression. These results suggest that NAc MSNs and ChNs are differentially regulated by excitatory projections from the IC and mPFC and that these corticoaccumbal excitatory inputs are modulated by M1 receptor activation.


Assuntos
Neurônios Colinérgicos/metabolismo , Núcleo Accumbens/metabolismo , Córtex Pré-Frontal/metabolismo , Acetilcolina/farmacologia , Animais , Animais Geneticamente Modificados/metabolismo , Carbacol/farmacologia , Colinérgicos/metabolismo , Neurônios Colinérgicos/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/efeitos dos fármacos , Potenciais Pós-Sinápticos Excitadores/fisiologia , Feminino , Ácido Glutâmico/metabolismo , Interneurônios/efeitos dos fármacos , Interneurônios/metabolismo , Masculino , Núcleo Accumbens/efeitos dos fármacos , Técnicas de Patch-Clamp/métodos , Córtex Pré-Frontal/efeitos dos fármacos , Ratos , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologia
7.
J Reprod Dev ; 67(3): 235-239, 2021 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-33853994

RESUMO

Saving space for sperm cryopreservation would aid mouse genetics research. We previously developed the ST (sperm freezing in ShorT STraw to reduce STorage space) method for cryopreserving mouse sperm in a smaller storage space than conventional methods. However, our ST method has two drawbacks: difficulties during freeze-thaw procedures and the potential risk of sperm loss during storage. Here, we refine ST, terming the new method improved ST (iST). In iST, the straw has an air-permeable filter and the straw container (2-ml cryotube) is endowed with air vents. As in our ST method, iST frozen-thawed sperm showed good performance upon in vitro fertilization. Moreover, up to nine straws can be stored in one cryotube, occupying less storage space than conventional methods. This method provides an easy and space-saving cryopreservation method for mouse sperm, and thus will be valuable for mouse genetics researchers.


Assuntos
Criopreservação/métodos , Preservação do Sêmen/métodos , Motilidade dos Espermatozoides , Animais , Fertilização in vitro , Congelamento , Masculino , Camundongos , Análise do Sêmen
8.
Proc Natl Acad Sci U S A ; 114(49): 13042-13047, 2017 12 05.
Artigo em Inglês | MEDLINE | ID: mdl-29158391

RESUMO

Although maternal nurturing behavior is extremely important for the preservation of a species, our knowledge of the biological underpinnings of these behaviors is insufficient. Here we show that the degree of a mother's nurturing behavior is regulated by factors present during her own fetal development. We found that Cin85-deficient (Cin85-/-) mother mice had reduced pituitary hormone prolactin (PRL) secretion as a result of excessive dopamine signaling in the brain. Their offspring matured normally and produced their own pups; however, nurturing behaviors such as pup retrieval and nursing were strongly inhibited. Surprisingly, when WT embryos were transplanted into the fallopian tubes of Cin85-/- mice, they also exhibited inhibited nurturing behavior as adults. Conversely, when Cin85-/- embryos were transplanted into the fallopian tubes of WT mice, the resultant pups exhibited normal nurturing behaviors as adults. When PRL was administered to Cin85-/- mice during late pregnancy, a higher proportion of the resultant pups exhibited nurturing behaviors as adults. This correlates with our findings that neural circuitry associated with nurturing behaviors was less active in pups born to Cin85-/- mothers, but PRL administration to mothers restored neural activity to normal levels. These results suggest that the prenatal period is extremely important in determining the expression of nurturing behaviors in the subsequent generation, and that maternal PRL is one of the critical factors for expression. In conclusion, perinatally secreted maternal PRL affects the expression of nurturing behaviors not only in a mother, but also in her pups when they have reached adulthood.


Assuntos
Encéfalo/metabolismo , Dopamina/metabolismo , Comportamento Materno , Proteínas de Neoplasias/genética , Proteínas do Tecido Nervoso/genética , Efeitos Tardios da Exposição Pré-Natal/genética , Prolactina/genética , Proteínas Adaptadoras de Transdução de Sinal , Animais , Animais Recém-Nascidos , Comportamento Animal , Encéfalo/fisiopatologia , Transferência Embrionária , Feminino , Regulação da Expressão Gênica no Desenvolvimento , Camundongos , Camundongos Knockout , Mães , Proteínas de Neoplasias/deficiência , Proteínas do Tecido Nervoso/deficiência , Gravidez , Efeitos Tardios da Exposição Pré-Natal/metabolismo , Efeitos Tardios da Exposição Pré-Natal/fisiopatologia , Prolactina/metabolismo , Maturidade Sexual/fisiologia , Transdução de Sinais
9.
Proc Natl Acad Sci U S A ; 113(38): 10702-7, 2016 09 20.
Artigo em Inglês | MEDLINE | ID: mdl-27601664

RESUMO

GABA acts as the major inhibitory neurotransmitter in the mammalian brain, shaping neuronal and circuit activity. For sustained synaptic transmission, synaptic vesicles (SVs) are required to be recycled and refilled with neurotransmitters using an H(+) electrochemical gradient. However, neither the mechanism underlying vesicular GABA uptake nor the kinetics of GABA loading in living neurons have been fully elucidated. To characterize the process of GABA uptake into SVs in functional synapses, we monitored luminal pH of GABAergic SVs separately from that of excitatory glutamatergic SVs in cultured hippocampal neurons. By using a pH sensor optimal for the SV lumen, we found that GABAergic SVs exhibited an unexpectedly higher resting pH (∼6.4) than glutamatergic SVs (pH ∼5.8). Moreover, unlike glutamatergic SVs, GABAergic SVs displayed unique pH dynamics after endocytosis that involved initial overacidification and subsequent alkalization that restored their resting pH. GABAergic SVs that lacked the vesicular GABA transporter (VGAT) did not show the pH overshoot and acidified further to ∼6.0. Comparison of luminal pH dynamics in the presence or absence of VGAT showed that VGAT operates as a GABA/H(+) exchanger, which is continuously required to offset GABA leakage. Furthermore, the kinetics of GABA transport was slower (τ > 20 s at physiological temperature) than that of glutamate uptake and may exceed the time required for reuse of exocytosed SVs, allowing reuse of incompletely filled vesicles in the presence of high demand for inhibitory transmission.


Assuntos
Neurônios/metabolismo , Neurotransmissores/metabolismo , Proteínas Vesiculares de Transporte de Aminoácidos Inibidores/metabolismo , Ácido gama-Aminobutírico/metabolismo , Animais , Exocitose/genética , Ácido Glutâmico/metabolismo , Hipocampo/metabolismo , Hipocampo/fisiologia , Concentração de Íons de Hidrogênio , Cinética , Camundongos , Neurônios/fisiologia , Neurotransmissores/genética , Terminações Pré-Sinápticas/metabolismo , Terminações Pré-Sinápticas/fisiologia , Sinapses/genética , Sinapses/metabolismo , Transmissão Sináptica/fisiologia , Vesículas Sinápticas/metabolismo , Proteínas Vesiculares de Transporte de Aminoácidos Inibidores/genética
10.
J Reprod Dev ; 64(6): 541-545, 2018 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-30270280

RESUMO

Efficient cryopreservation and transportation of mouse sperm are among the most desirable strategies for current and future research on mouse genetics. However, the current method for sperm cryopreservation uses an 11-cm plastic straw, which is a bulky and fragile container. Developing an alternative to overcome the limitations associated with this method would accelerate biomedical research. Here, we developed the ST (sperm-freezing in ShorT STraw to reduce STorage space) method for cryopreserving mouse sperm in short 3.8-cm plastic straws. Up to nine short straws can be stored in a cryotube, reducing storage space. We further show that sperm frozen by the ST method can be transported in liquid nitrogen or dry ice without any detrimental effects on subsequent fertilization and the birth rate. Our findings suggest that this sperm-freezing method is beneficial not only for individual laboratories but also for large-scale mutagenesis/knockout and phenotyping programs.


Assuntos
Criopreservação/veterinária , Preservação do Sêmen/veterinária , Motilidade dos Espermatozoides , Espermatozoides , Animais , Criopreservação/métodos , Gelo-Seco , Fertilização in vitro/veterinária , Congelamento , Masculino , Camundongos , Preservação do Sêmen/métodos
11.
J Neurochem ; 140(3): 395-403, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27419919

RESUMO

It was previously reported that functional glycine receptors were expressed in neonatal prefrontal cortex; however, the glycine-releasing cells were unknown. We hypothesized that astrocytes might be a major glycine source, and examined the glycine release properties of astrocytes. We also hypothesized that dopamine (DA) might be a trigger for the astrocytic glycine release, as numerous DA terminals localize in the cortex. We combined two different methods to confirm the glycine release from astrocytes. Firstly, we analyzed the supernatant of astrocytes by amino acid analyzer after DA stimulation, and detect significant glycine peak. Furthermore, we utilized a patch-clamp biosensor method to confirm the glycine release from astrocytes by using GlyRα1 and Glyß-expressing HEK293T cells, and detected significant glycine-evoked current upon DA stimulation. Thus, we clearly demonstrated that DA induces glycine release from astrocytes. Surprisingly, DA caused a functional reversal of astrocytic glycine transporter 1, an astrocytic type of glycine transporter, causing astrocytes to release glycine. Hence, astrocytes transduce pre-synaptic DA signals to glycine signals through a reversal of astrocytic glycine transporter 1 to regulate neuronal excitability. Cover Image for this issue: doi: 10.1111/jnc.13785.


Assuntos
Astrócitos/metabolismo , Proteínas da Membrana Plasmática de Transporte de Glicina/metabolismo , Glicina/metabolismo , Animais , Astrócitos/efeitos dos fármacos , Córtex Cerebral/citologia , Córtex Cerebral/efeitos dos fármacos , Córtex Cerebral/metabolismo , Dopamina/metabolismo , Dopamina/farmacologia , Feminino , Células HEK293 , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL
12.
BMC Biol ; 14(1): 103, 2016 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-27912755

RESUMO

BACKGROUND: The specificity of synaptic connections is fundamental for proper neural circuit function. Specific neuronal connections that underlie information processing in the sensory cortex are initially established without sensory experiences to a considerable extent, and then the connections are individually refined through sensory experiences. Excitatory neurons arising from the same single progenitor cell are preferentially connected in the postnatal cortex, suggesting that cell lineage contributes to the initial wiring of neurons. However, the postnatal developmental process of lineage-dependent connection specificity is not known, nor how clonal neurons, which are derived from the same neural stem cell, are stamped with the identity of their common neural stem cell and guided to form synaptic connections. RESULTS: We show that cortical excitatory neurons that arise from the same neural stem cell and reside within the same layer preferentially establish reciprocal synaptic connections in the mouse barrel cortex. We observed a transient increase in synaptic connections between clonal but not nonclonal neuron pairs during postnatal development, followed by selective stabilization of the reciprocal connections between clonal neuron pairs. Furthermore, we demonstrate that selective stabilization of the reciprocal connections between clonal neuron pairs is impaired by the deficiency of DNA methyltransferase 3b (Dnmt3b), which determines DNA-methylation patterns of genes in stem cells during early corticogenesis. Dnmt3b regulates the postnatal expression of clustered protocadherin (cPcdh) isoforms, a family of adhesion molecules. We found that cPcdh deficiency in clonal neuron pairs impairs the whole process of the formation and stabilization of connections to establish lineage-specific connection reciprocity. CONCLUSIONS: Our results demonstrate that local, reciprocal neural connections are selectively formed and retained between clonal neurons in layer 4 of the barrel cortex during postnatal development, and that Dnmt3b and cPcdhs are required for the establishment of lineage-specific reciprocal connections. These findings indicate that lineage-specific connection reciprocity is predetermined by Dnmt3b during embryonic development, and that the cPcdhs contribute to postnatal cortical neuron identification to guide lineage-dependent synaptic connections in the neocortex.


Assuntos
Caderinas/metabolismo , Neurônios/metabolismo , Sinapses/metabolismo , Animais , Caderinas/genética , Células Cultivadas , DNA (Citosina-5-)-Metiltransferases/genética , DNA (Citosina-5-)-Metiltransferases/metabolismo , Eletrofisiologia , Feminino , Hibridização In Situ , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Vias Neurais/fisiologia , Transmissão Sináptica/genética , Transmissão Sináptica/fisiologia , DNA Metiltransferase 3B
13.
Transgenic Res ; 25(4): 413-24, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-26885830

RESUMO

Childhood-onset dermatitis is one of the most common skin disorders in children. Although various mouse models that mirror aspects of dermatitis have become available, there is still a need for an animal model that develops dermatitis in childhood and is more suitable for performing tissue transplantation experiments. There is emerging evidence that peripheral blood T lymphocytes from patients with dermatitis have significantly increased telomerase activity. Here, we developed telomerase reverse transcriptase (TERT)-expressing transgenic (Tg) rats that spontaneously developed eczematous skin inflammation in childhood. Newborn TERT-Tg rats developed visible dermatitis in 56 % of cases, and the skin lesions microscopically showed spongiosis and acanthosis with infiltration of lymphocytes, eosinophils and mast cells. TERT-Tg rats with dermatitis exhibited increased CD4 (2.5-fold) and CD8 (fivefold) T cell numbers compared with dermatitis-free TERT-Tg rats. Stronger TERT activity was observed in the peripheral lymphocytes of dermatitis-positive TERT-Tg rats than those of dermatitis-free TERT-Tg rats. RT-PCR analysis revealed that IL-4 was markedly elevated in the spleen of dermatitis-positive TERT-Tg rats, and that interferon-gamma was increased in the dermatitis lesions. Moreover, skin grafting of TERT-Tg rats with dermatitis onto T cell-deficient nude rats demonstrated that the inflamed skin lesions could not be maintained. Taken together, the results suggest that TERT activation in T lymphocytes is one of the potential predisposing factors for dermatitis. Moreover, our results demonstrated that the TERT-Tg rats mirror aspects of human childhood-onset dermatitis and that these animals represent a potential animal model system for studying childhood-onset dermatitis.


Assuntos
Dermatite/etiologia , Ratos Transgênicos/genética , Telomerase/genética , Animais , Dermatite/genética , Dermatite/patologia , Modelos Animais de Doenças , Feminino , Regulação da Expressão Gênica , Pele/patologia , Linfócitos T/fisiologia , Transgenes
14.
J Neurosci ; 33(11): 4683-92, 2013 Mar 13.
Artigo em Inglês | MEDLINE | ID: mdl-23486942

RESUMO

After ischemic stroke, the corresponding area contralateral to the lesion may partly compensate for the loss of function. We previously reported the remodeling of neuronal circuits in the contralateral somatosensory cortex (SSC) during the first week after infarction for processing bilateral information, resulting in functional compensation. However, the underlying processes in the contralateral hemisphere after stroke have not yet been fully elucidated. Recent studies have shown that astrocytes may play critical roles in synaptic reorganization and functional compensation after a stroke. Thus, we aim to clarify the contribution of astrocytes using a rodent stroke model. In vivo calcium imaging showed a significantly large number of astrocytes in the contralateral SSC responding to ipsilateral limb stimulation at the first week after infarction. Simultaneously, extracellular glutamine level increased, indicating the involvement of astrocytes in the conversion of glutamate to glutamine, which may be an important process for functional recovery. This hypothesis was supported further by the observation that application of (2S,3S)-3-{3-[4-(trifluoromethyl)benzoylamino]benzyloxy} aspartate, a glial glutamate transporter blocker, disturbed the functional recovery. These findings indicate the involvement of astrocytes in functional remodeling/recovery in the area contralateral to the lesion. Our study has provided new insights into the mechanisms underlying synaptic remodeling after cerebral infarction, which contributes to the development of effective therapeutic approaches for patients after a stroke.


Assuntos
Astrócitos/fisiologia , Lateralidade Funcional/fisiologia , Córtex Somatossensorial/fisiopatologia , Acidente Vascular Cerebral/patologia , Aminometiltransferase/genética , Aminometiltransferase/metabolismo , Análise de Variância , Animais , Ácido Aspártico/análogos & derivados , Ácido Aspártico/uso terapêutico , Cálcio/metabolismo , Modelos Animais de Doenças , Transportador 1 de Aminoácido Excitatório/genética , Transportador 1 de Aminoácido Excitatório/metabolismo , Transportador 2 de Aminoácido Excitatório/genética , Transportador 2 de Aminoácido Excitatório/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/fisiologia , Ácido Glutâmico/metabolismo , Glicina/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microdiálise , Atividade Motora , Neurônios/metabolismo , Estimulação Física , RNA Mensageiro/metabolismo , Córtex Somatossensorial/efeitos dos fármacos , Córtex Somatossensorial/patologia , Acidente Vascular Cerebral/tratamento farmacológico , Fatores de Tempo , Vibrissas/inervação
15.
Eur J Neurosci ; 39(8): 1294-313, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24593297

RESUMO

Cerebellar function is regulated by cholinergic mossy fiber inputs that are primarily derived from the medial vestibular nucleus (MVN) and prepositus hypoglossi nucleus (PHN). In contrast to the growing evidence surrounding cholinergic transmission and its functional significance in the cerebellum, the intrinsic and synaptic properties of cholinergic projection neurons (ChPNs) have not been clarified. In this study, we generated choline acetyltransferase (ChAT)-tdTomato transgenic rats, which specifically express the fluorescent protein tdTomato in cholinergic neurons, and used them to investigate the response properties of ChPNs identified via retrograde labeling using whole-cell recordings in brainstem slices. In response to current pulses, ChPNs exhibited two afterhyperpolarisation (AHP) profiles and three firing patterns; the predominant AHP and firing properties differed between the MVN and PHN. Morphologically, the ChPNs were separated into two types based on their soma size and dendritic extensions. Analyses of the firing responses to time-varying sinusoidal current stimuli revealed that ChPNs exhibited different firing modes depending on the input frequencies. The maximum frequencies in which each firing mode was observed were different between the neurons that exhibited distinct firing patterns. Analyses of the current responses to the application of neurotransmitter receptor agonists revealed that the ChPNs expressed (i) AMPA- and NMDA-type glutamate receptors, (ii) GABAA and glycine receptors, and (iii) muscarinic and nicotinic acetylcholine receptors. The current responses mediated by these receptors of MVN ChPNs were not different from those of PHN ChPNs. These findings suggest that ChPNs receive various synaptic inputs and encode those inputs appropriately across different frequencies.


Assuntos
Potenciais de Ação , Colina O-Acetiltransferase/metabolismo , Neurônios Colinérgicos/fisiologia , Potenciais Sinápticos , Núcleos Vestibulares/fisiologia , Animais , Colina O-Acetiltransferase/genética , Neurônios Colinérgicos/efeitos dos fármacos , Neurônios Colinérgicos/metabolismo , Fármacos Atuantes sobre Aminoácidos Excitatórios/farmacologia , GABAérgicos/farmacologia , Camundongos , Camundongos Endogâmicos C57BL , Ratos , Ratos Long-Evans , Ratos Transgênicos , Núcleos Vestibulares/citologia , Núcleos Vestibulares/metabolismo
16.
Front Cell Neurosci ; 18: 1349878, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38433862

RESUMO

Protein kinase C γ (PKCγ), a neuronal isoform present exclusively in the central nervous system, is most abundantly expressed in cerebellar Purkinje cells (PCs). Targeted deletion of PKCγ causes a climbing fiber synapse elimination in developing PCs and motor deficit. However, physiological roles of PKCγ in adult mouse PCs are little understood. In this study, we aimed to unravel the roles of PKCγ in mature mouse PCs by deleting PKCγ from adult mouse PCs of PKCγfl/fl mice via cerebellar injection of adeno-associated virus (AAV) vectors expressing Cre recombinase under the control of the PC-specific L7-6 promoter. Whole cell patch-clamp recording of PCs showed higher intrinsic excitability in PCs virally lacking PKCγ [PKCγ-conditional knockout (PKCγ-cKO) PCs] than in wild-type (WT) mouse PCs in the zebrin-negative module, but not in the zebrin-positive module. AAV-mediated PKCγ re-expression in PKCγ-deficient mouse PCs in the zebrin-negative module restored the enhanced intrinsic excitability to a level comparable to that of wild-type mouse PCs. In parallel with higher intrinsic excitability, we found larger hyperpolarization-activated cyclic nucleotide-gated (HCN) channel currents in PKCγ-cKO PCs located in the zebrin-negative module, compared with those in WT mouse PCs in the same region. However, pharmacological inhibition of the HCN currents did not restore the enhanced intrinsic excitability in PKCγ-cKO PCs in the zebrin-negative module. These results suggested that PKCγ suppresses the intrinsic excitability in zebrin-negative PCs, which is likely independent of the HCN current inhibition.

17.
Anal Sci ; 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38748393

RESUMO

This study introduces the α-rhamnose (Rham)-conjugated prodrug of SN-38 (Rham-SN-38) as a promising alternative to irinotecan. α-rhamnosidase, responsible for SN-38 release from Rham-SN-38, does not express in human cells, minimizing individual variability and side effects. The injection of the α-rhamnosidase into the tumor tissues makes it possible, for the first time, to activate the Rham-SN-38. Furthermore, α-rhamnosidase demonstrates significantly higher activity than carboxylesterase, the specific enzyme activating irinotecan. SN-38 release mediated by α-rhamnosidase completes within 2 h, with a kcat/Km value approximately 5.0 × 104-fold higher than that of irinotecan. The 50% inhibition concentration (IC50) of Rham-SN-38 against three types of cancer cells and one normal cell exceeds 4.5 × 103 nM. The addition of α-rhamnosidase significantly increases cytotoxicity, with IC50 comparable to free SN-38. The QIC50, an index reflecting the difference in cytotoxicity with and without α-rhamnosidase, exceeds approximately 1.0 × 102-fold. Rham-SN-38, synthesized in this study, demonstrates significant potential as a prodrug for cancer therapy.

18.
World Neurosurg ; 2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38810873

RESUMO

OBJECTIVES: We retrospectively examined the initial experience and learning curve after the introduction of thrombectomy with the combined technique using an aspiration catheter and a stent retriever as first-line attempt for acute ischemic stroke. METHODS: Consecutive patients undergoing thrombectomy for acute ischemic stroke at our institution between January 2020 and December 2022 were divided into 3 groups according to the year of thrombectomy. Patient characteristics and procedural, safety, and clinical outcomes were compared between the three year periods to determine predictors of favorable clinical outcome. RESULTS: In 2020, 2021, and 2022, the numbers of patients were 74, 70, and 90, respectively, with similar patient characteristics across the three years; successful recanalization rates were 79.7%, 97.1%, and 93.3%, respectively (P < 0.01 for the first 2 years); median procedure times were 67, 43, and 32 minutes, respectively (P < 0.01 for the first 2 years and P = 0.018 for the last 2 years); first pass effect rates were 20.3%, 41.4%, and 44.4%, respectively (P < 0.01 for the first 2 years); symptomatic intracranial hemorrhage rates were 14.9%, 2.9%, and 1.1%, respectively (P = 0.018 for the first 2 years); and percentages of modified Rankin Scale score 0-2 at 90 days were 24.3%, 42.9%, and 41.1%, respectively (P = 0.022 for the first 2 years). Procedure time (P = 0.038) and successful recanalization (P = 0.041) were independent predictors of favorable clinical outcome. CONCLUSIONS: The learning curve effect of the combined technique may be associated with better clinical outcome due to increased successful recanalization rates, shortened procedure time, and reduced symptomatic intracranial hemorrhage.

19.
Nano Lett ; 12(7): 3711-5, 2012 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-22663563

RESUMO

We have fabricated a centimeter-size single-layer graphene device with a gate electrode, which can modulate the transmission of terahertz and infrared waves. Using time-domain terahertz spectroscopy and Fourier-transform infrared spectroscopy in a wide frequency range (10-10 000 cm(-1)), we measured the dynamic conductivity change induced by electrical gating and thermal annealing. Both methods were able to effectively tune the Fermi energy, E(F), which in turn modified the Drude-like intraband absorption in the terahertz as well as the "2E(F) onset" for interband absorption in the mid-infrared. These results not only provide fundamental insight into the electromagnetic response of Dirac fermions in graphene but also demonstrate the key functionalities of large-area graphene devices that are desired for components in terahertz and infrared optoelectronics.

20.
Elife ; 122023 06 05.
Artigo em Inglês | MEDLINE | ID: mdl-37272607

RESUMO

Neurons form dense neural circuits by connecting to each other via synapses and exchange information through synaptic receptors to sustain brain activities. Excitatory postsynapses form and mature on spines composed predominantly of actin, while inhibitory synapses are formed directly on the shafts of dendrites where both actin and microtubules (MTs) are present. Thus, it is the accumulation of specific proteins that characterizes inhibitory synapses. In this study, we explored the mechanisms that enable efficient protein accumulation at inhibitory postsynapse. We found that some inhibitory synapses function to recruit the plus end of MTs. One of the synaptic organizers, Teneurin-2 (TEN2), tends to localize to such MT-rich synapses and recruits MTs to inhibitory postsynapses via interaction with MT plus-end tracking proteins EBs. This recruitment mechanism provides a platform for the exocytosis of GABAA receptors. These regulatory mechanisms could lead to a better understanding of the pathogenesis of disorders such as schizophrenia and autism, which are caused by excitatory/inhibitory (E/I) imbalances during synaptogenesis.


Assuntos
Actinas , Receptores de GABA-A , Receptores de GABA-A/metabolismo , Actinas/metabolismo , Neurônios/metabolismo , Sinapses/metabolismo , Microtúbulos/metabolismo , Exocitose
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