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1.
Synapse ; 66(5): 453-64, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22213465

RESUMO

Early-onset generalized dystonia, DYT1, is caused by a mutation in the gene encoding the evolutionarily conserved AAA+ ATPase torsinA. Synaptic abnormalities have been implicated in DYT1 dystonia, but the details of the synaptic pathophysiology are only partially understood. Here, we demonstrate a novel role for torsinA in synaptic vesicle recycling, using cultured hippocampal neurons from a knock-in mouse model of DYT1 dystonia (ΔE-torsinA) and live-cell imaging with styryl FM dyes. Neurons from heterozygous ΔE-torsinA mice released a larger fraction of the total recycling pool (TRP) during a single round of electrical stimulation than did wild-type neurons. Moreover, when the neurons were subjected to prior high activity, the time course of release was shortened. In neurons from homozygous mice, these enhanced exocytosis phenotypes were similar, but in addition the size of the TRP was reduced. Notably, when release was triggered by applying a calcium ionophore rather than electrical stimuli, neither a single nor two ΔE-torsinA alleles affected the time course of release. Thus, the site of action of ΔE-torsinA is at or upstream of the rise in calcium concentration in nerve terminals. Our results suggest that torsinA regulates synaptic vesicle recycling in central neurons. They also indicate that this regulation is influenced by neuronal activity, further supporting the idea that synaptic abnormalities contribute to the pathophysiology of DYT1 dystonia.


Assuntos
Distúrbios Distônicos/metabolismo , Chaperonas Moleculares/metabolismo , Neurônios/metabolismo , Vesículas Sinápticas/metabolismo , Animais , Células Cultivadas , Distúrbios Distônicos/genética , Endocitose/fisiologia , Exocitose/fisiologia , Técnicas de Introdução de Genes , Heterozigoto , Camundongos , Modelos Animais , Chaperonas Moleculares/genética , Vesículas Sinápticas/genética
2.
Synapse ; 66(9): 807-22, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22588999

RESUMO

TorsinA is an evolutionarily conserved AAA+ ATPase, and human patients with an in-frame deletion of a single glutamate (ΔE) codon from the encoding gene suffer from autosomal-dominant, early-onset generalized DYT1 dystonia. Although only 30-40% of carriers of the mutation show overt motor symptoms, most experience enhanced excitability of the central nervous system. The cellular mechanism responsible for this change in excitability is not well understood. Here we show the effects of the ΔE-torsinA mutation on miniature neurotransmitter release from neurons. Neurotransmitter release was characterized in cultured hippocampal neurons obtained from wild-type, heterozygous, and homozygous ΔE-torsinA knock-in mice using two approaches. In the first approach, patch-clamp electrophysiology was used to record glutamate-mediated miniature excitatory postsynaptic currents (mEPSCs) in the presence of the Na⁺ channel blocker tetrodotoxin (TTX) and absence of GABA(A) receptor antagonists. The intervals between mEPSC events were significantly shorter in neurons obtained from the mutant mice than in those obtained from wild-type mice. In the second approach, the miniature exocytosis of synaptic vesicles was detected by imaging the unstimulated release of FM dye from the nerve terminals in the presence of TTX. Cumulative FM dye release was higher in neurons obtained from the mutant mice than in those obtained from wild-type mice. The number of glutamatergic nerve terminals was also assessed, and we found that this number was unchanged in heterozygous relative to wild-type neurons, but slightly increased in homozygous neurons. Notably, in both heterozygous and homozygous neurons, the unitary synaptic charge during each mEPSC event was unchanged. Overall, our results suggest more frequent miniature glutamate release in neurons with ΔE-torsinA mutations. This change may be one of the underlying mechanisms by which the excitability of the central nervous system is enhanced in the context of DYT1 dystonia. Moreover, qualitative differences between heterozygous and homozygous neurons with respect to certain synaptic properties indicate that the abnormalities observed in homozygotes may reflect more than a simple gene dosage effect.


Assuntos
Exocitose/fisiologia , Ácido Glutâmico/metabolismo , Hipocampo/fisiologia , Potenciais Pós-Sinápticos em Miniatura/fisiologia , Chaperonas Moleculares/genética , Neurônios/fisiologia , Animais , Modelos Animais de Doenças , Distonia Muscular Deformante/genética , Potenciais Pós-Sinápticos Excitadores/fisiologia , Heterozigoto , Hipocampo/citologia , Homozigoto , Potenciais Pós-Sinápticos Inibidores/fisiologia , Camundongos , Camundongos Transgênicos , Chaperonas Moleculares/metabolismo , Mutação , Receptores de GABA-A/metabolismo , Canais de Sódio/efeitos dos fármacos , Canais de Sódio/metabolismo , Vesículas Sinápticas/metabolismo , Tetrodotoxina/farmacologia , Proteína Vesicular 1 de Transporte de Glutamato/metabolismo
3.
Proc Natl Acad Sci U S A ; 106(23): 9483-8, 2009 Jun 09.
Artigo em Inglês | MEDLINE | ID: mdl-19470479

RESUMO

The ganglioside GM3 synthase (SAT-I), encoded by a single-copy gene, is a primary glycosyltransferase for the synthesis of complex gangliosides. In SAT-I null mice, hearing ability, assessed by brainstem auditory-evoked potentials (BAEP), was impaired at the onset of hearing and had been completely lost by 17 days after birth (P17), showing a deformity in hair cells in the organ of Corti. By 2 months of age, the organ of Corti had selectively and completely disappeared without effect on balance or motor function or in the histology of vestibule. Interestingly, spatiotemporal changes in localization of individual gangliosides, including GM3 and GT1b, were observed during the postnatal development and maturation of the normal inner ear. GM3 expressed in almost all regions of cochlea at P3, but at the onset of hearing it distinctly localized in stria vascularis, spiral ganglion, and the organ of Corti. In addition, SAT-I null mice maintain the function of stria vascularis, because normal potassium concentration and endocochlear potential of endolymph were observed even when they lost the BAEP completely. Thus, the defect of hearing ability of SAT-I null mice could be attributed to the functional disorganization of the organ of Corti, and the expression of gangliosides, especially GM3, during the early part of the functional maturation of the cochlea could be essential for the acquisition and maintenance of hearing function.


Assuntos
Surdez/genética , Órgão Espiral/fisiologia , Sialiltransferases/genética , Sialiltransferases/metabolismo , Animais , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos , Mutação , Órgão Espiral/embriologia , Reflexo de Sobressalto , Estria Vascular/fisiologia
4.
Brain Res ; 1228: 68-72, 2008 Sep 04.
Artigo em Inglês | MEDLINE | ID: mdl-18619421

RESUMO

Tetraethylammonium (TEA)-sensitive potassium currents in the cochlear inner hair cells (IHCs) possess the kinetics of fast inactivation. IHCs of guinea-pigs were separately isolated from the apical and basal turns and the tonotopic gradient of inactivation kinetics was investigated. TEA-sensitive potassium currents showed voltage-dependent time constant of the inactivation phase both in apical and basal IHCs, however, the degree of inactivation (compared to the ratio between the steady-state current and initial peak current) was voltage-independent. Inactivation time constant was faster in basal IHCs than in apical IHCs and the degree of inactivation was greater in basal IHCs than in apical IHCs, suggesting that inactivation was more predominant in basal IHCs than in apical IHCs.


Assuntos
Cóclea/citologia , Células Ciliadas Auditivas Internas/fisiologia , Canais de Potássio/fisiologia , Animais , Cóclea/metabolismo , Cóclea/fisiologia , Condutividade Elétrica , Eletrofisiologia , Cobaias , Células Ciliadas Auditivas Internas/efeitos dos fármacos , Células Ciliadas Auditivas Internas/metabolismo , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Técnicas de Patch-Clamp , Bloqueadores dos Canais de Potássio/farmacologia , Canais de Potássio/metabolismo , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/fisiologia , Tetraetilamônio/farmacologia
5.
Nat Neurosci ; 7(1): 17-23, 2004 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-14699415

RESUMO

Early in postnatal development, inhibitory inputs to rat lateral superior olive (LSO) neurons change from releasing predominantly GABA to releasing predominantly glycine into the synapse. Here we show that spontaneous miniature inhibitory postsynaptic currents (mIPSCs) also change from GABAergic to glycinergic over the first two postnatal weeks. Many 'mixed' mIPSCs, resulting from co-release of glycine and GABA from the same vesicles, are seen during this transition. Immunohistochemistry showed that a large number of terminals contained both GABA and glycine at postnatal day 8 (P8). By P14, both the content of GABA in these mixed terminals and the contribution of GABA to the mixed mIPSCs had decreased. The content of glycine in terminals increased over the same period. Our results indicate that switching from GABAergic to glycinergic inputs to the LSO may occur at the level of a single presynaptic terminal. This demonstrates a new form of developmental plasticity at the level of a single central synapse.


Assuntos
Glicina/metabolismo , Núcleo Olivar/crescimento & desenvolvimento , Núcleo Olivar/metabolismo , Terminações Pré-Sinápticas/metabolismo , Ácido gama-Aminobutírico/metabolismo , Animais , Animais Recém-Nascidos , Bicuculina/farmacologia , Núcleo Olivar/efeitos dos fármacos , Terminações Pré-Sinápticas/efeitos dos fármacos , Ratos , Ratos Wistar , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologia
6.
Neurosci Res ; 55(2): 161-70, 2006 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-16595155

RESUMO

Bilirubin is a well-known neurotoxin that can result in multiple neurologic deficits. Previous studies have suggested that bilirubin affects aspects of synaptic transmission; however the acute effects of bilirubin on synaptic transmission have not been examined in real-time. In this study, using whole-cell voltage-clamp recordings, we observed the effect of bilirubin on inhibitory postsynaptic currents (IPSC) in postnatal 13-15-day-old neurons dissociated from lateral superior olive nuclei (LSO), one of the brainstem auditory nucleus that are highly vulnerable to bilirubin. The results showed that 10(-5)M bilirubin increased the frequency of spontaneous IPSC without causing change in their amplitudes or in the response to bath applied glycine, suggesting a presynaptic locus for the action. In the presence of tetrodotoxin, the frequency of miniature IPSC was also potentiated by 10(-5)M bilirubin. The facilitation by bilirubin was concentration dependent and increased with an increase in exposure time. Bicuculline only partially reduced the action of bilirubin. The action of bilirubin was observed in extracellular Ca(2+)-free ([Ca(2+)](o) free) solution but was fully occluded by pretreatment with BAPTA-AM in [Ca(2+)](o) free solution. Thus, in LSO neurons, bilirubin facilitates inhibitory synaptic transmission, in a manner independent of voltage-activated Na(+) and Ca(2+) channels but dependent on presynaptic [Ca(2+)](i). The increase of inhibitory synaptic transmission in response to acute bilirubin is a novel effect of bilirubin on the central nervous system and may have implications for neurotoxicity and the impairment of auditory transduction seen in hyperbilirubinemia.


Assuntos
Bilirrubina/farmacologia , Inibição Neural/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Núcleo Olivar/citologia , Transmissão Sináptica/efeitos dos fármacos , Animais , Animais Recém-Nascidos , Bicuculina/farmacologia , Quelantes/farmacologia , Relação Dose-Resposta a Droga , Interações Medicamentosas , Ácido Egtázico/análogos & derivados , Ácido Egtázico/farmacologia , Estimulação Elétrica/métodos , Feminino , Antagonistas GABAérgicos/farmacologia , Técnicas In Vitro , Masculino , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Potenciais da Membrana/efeitos da radiação , Técnicas de Patch-Clamp/métodos , Ratos , Estricnina/farmacologia , Tetrodotoxina/farmacologia , Fatores de Tempo
7.
Otol Neurotol ; 27(2): 242-8; discussion 249, 2006 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-16436996

RESUMO

OBJECTIVE: Treatment outcomes for squamous cell carcinoma of the temporal bone were evaluated regarding stage, therapeutic strategy, and prognostic factors. STUDY DESIGN: Retrospective case review. SETTING: University hospital and outpatient clinic. PATIENTS: Twenty-five patients with primary squamous cell carcinoma of the external auditory canal and middle ear. INTERVENTION: Preoperative chemoradiotherapy and radiotherapy were used in 7 of 12 patients. Lateral temporal bone resection was performed for the lesions not beyond the tympanic membrane. Subtotal temporal bone resection was chosen for lesions extending to the middle ear cavity when there was no invasion to the pyramidal apex, carotid canal, or dura or metastasis. Others were conservatively treated by chemoradiotherapy. When the performance status was poor or an agreement regarding the operation could not be reached, the treatment was modified. MAIN OUTCOME MEASURE: Estimated survival rates. RESULTS: The 3-year estimated survival for T1 and T2 lesions was 100%. The 5-year estimated survival for T3 and T4 lesions was 80% and 35%, respectively. The 5-year estimated survival improved up to 75% for T4 tumors with operation and 16% for those without operation after 47 months. The tumor-free surgical margin is significantly related to patient survival in T3 and T4 lesions. Multivariate analysis predicted that concomitant chronic otitis media and positive lymph nodes were significantly associated with poorer survival. CONCLUSION: The tumor-free surgical margin was important to survival. When T4 lesions did not involve the pyramidal apex, carotid canal, dura, or any lymph nodes, the surgical intervention improved the estimated survival rate to a level as good as T3 lesions.


Assuntos
Carcinoma de Células Escamosas/terapia , Meato Acústico Externo/cirurgia , Neoplasias da Orelha/terapia , Orelha Média/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma de Células Escamosas/mortalidade , Carcinoma de Células Escamosas/patologia , Quimioterapia Adjuvante , Intervalo Livre de Doença , Meato Acústico Externo/patologia , Neoplasias da Orelha/mortalidade , Neoplasias da Orelha/patologia , Orelha Média/patologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Cuidados Pré-Operatórios , Prognóstico , Radioterapia Adjuvante , Estudos Retrospectivos , Taxa de Sobrevida , Tomografia Computadorizada por Raios X , Resultado do Tratamento
8.
Neurosci Res ; 53(4): 396-403, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16198438

RESUMO

The physiological and pharmacological properties of gamma-aminobutyric acid (GABA)-induced responses were investigated in acutely isolated spiral ganglion cells (SGCs) of guinea pig by using either a nystatin-perforated patch recording configuration or a conventional whole-cell patch recording mode combined with rapid drug application. GABA and GABA(A) subtype receptor agonist, muscimol, induced inward currents in a concentration-dependent manner in 74% of all cells. The current-voltage relationship for the GABA response indicated the GABA-induced current in SGCs is carried by Cl-. Bicuculline (BIC), strychnine (STR), and picrotoxin (PTX) suppressed the GABA response in a concentration-dependent manner. BIC and STR, and PTX blocked the GABA response in a competitive manner and in a non-competitive manner, respectively. For inorganic antagonists, Cd2+ and Ni2+ also inhibited the GABA response. On the other hand, Zn2+ failed to suppress the GABA response in SGCs. An antibiotic, benzylpenicillin, suppressed the GABA response. The GABA response was augmented by both a barbiturate derivative, pentobarbital (PB), and a benzodiazepine derivative, diazepam. The results suggest clearly that the physiological and pharmacological characteristics of GABA(A) receptor on acutely isolated guinea pig SGCs are quite similar to the common GABA(A) receptor found in other sensory ganglion cells.


Assuntos
Neurônios/metabolismo , Gânglio Espiral da Cóclea/metabolismo , Ácido gama-Aminobutírico/metabolismo , Animais , Células Cultivadas , Feminino , Agonistas GABAérgicos/farmacologia , Antagonistas GABAérgicos/farmacologia , Cobaias , Masculino , Potenciais da Membrana/efeitos dos fármacos , Potenciais da Membrana/fisiologia , Neurônios/efeitos dos fármacos , Técnicas de Patch-Clamp , Receptores de GABA-A/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Gânglio Espiral da Cóclea/citologia
9.
Auris Nasus Larynx ; 32(3): 237-41, 2005 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-15893440

RESUMO

BACKGROUND: Automatic continuous positive airway pressure (auto-CPAP) machines differ mainly in algorithms used for respiratory event detection and pressure control. The auto-CPAP machines operated by novel algorithms are expected to have better performance than the earlier ones in the treatment of obstructive sleep apnea syndrome (OSAS). OBJECTIVES: The purpose of this study was to determine the therapeutic characteristics between two different auto-CPAP devices, i.e., the third-generation flow-based (f-APAP) and the second-generation vibration-based (v-APAP) machines, during the first night treatment of OSAS. METHODS: We retrospectively reviewed the polysomnography (PSG) recordings of 43 OSAS patients who were initially performed an overnight diagnostic PSG to confirm the disease and afterwards received the first night auto-CPAP treatment with using either the f-APAP (n=22) or v-APAP (n=21) device under another PSG evaluation. RESULTS: There were 13.6% and 61.9% patients who remained a residual apnea/hypopnea index more than 5 during the f-APAP and v-APAP application, respectively (P<0.005). The f-APAP was more effective than the v-APAP in reducing apnea/hypopnea index (P=0.003), hypopnea index (P=0.023) and apnea index (P=0.007), improving the lowest oxygen saturation index (P=0.007) and shortening stage 1 sleep (P=0.016). However, the f-APAP was less sufficient than the v-APAP in reducing arousal/awakening index (P=0.02). CONCLUSION: These findings suggest that the f-APAP works better than the v-APAP in abolishing breathing abnormities in the treatment of OSAS; however, the f-APAP device might still have some potential limitations in the clinical application.


Assuntos
Pressão Positiva Contínua nas Vias Aéreas/instrumentação , Apneia Obstrutiva do Sono/terapia , Adulto , Idoso , Análise de Variância , Desenho de Equipamento , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polissonografia , Estudos Retrospectivos , Resultado do Tratamento
10.
Neurosci Res ; 48(2): 211-20, 2004 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-14741396

RESUMO

A developmental change in GABA and glycine responses, from a depolarization to a hyperpolarization, have been reported for a range of CNS neurons, and has been demonstrated to be due to a developmental decrease in the intracellular Cl- concentration ([Cl-](i)). We examined [Cl-](i) in isolated rat lateral superior olive (LSO) neurons using patch-clamp recordings of glycine gated Cl- currents and by measuring intracellular Cl- -fluorescence. In neurons from 14-16-day-old rats (P14-P16), which had previously received unilateral or bilateral cochlear ablations before the onset of hearing, there was no developmental decrease in [Cl-](i). No significant differences in [Cl-](i) were observed amongst rats with either ipsi- and contralateral ablations. Implanted strychnine pellets also prevented the decrease in [Cl-](i) in most neurons. In some of these neurons in which [Cl-](i) remained high, there was a lack of expression of the K+-Cl- cotransporter 2 (KCC2) mRNA. These results demonstrate that the developmental decrease in [Cl-](i) in LSO neurons is dependent on neuronal activity and that both GABAergic/glycinergic and glutamatergic afferent activity contribute to this maturation of the Cl- regulatory mechanisms.


Assuntos
Cloretos/metabolismo , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Líquido Intracelular/metabolismo , Neurônios/metabolismo , Núcleo Olivar/metabolismo , Estimulação Acústica/métodos , Animais , Animais Recém-Nascidos , Cóclea/crescimento & desenvolvimento , Cóclea/metabolismo , Núcleo Olivar/crescimento & desenvolvimento , Ratos
11.
J Neurosci Methods ; 223: 92-113, 2014 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-24333471

RESUMO

BACKGROUND: Images in biomedical imaging research are often affected by non-specific background noise. This poses a serious problem when the noise overlaps with specific signals to be quantified, e.g. for their number and intensity. A simple and effective means of removing background noise is to prepare a filtered image that closely reflects background noise and to subtract it from the original unfiltered image. This approach is in common use, but its effectiveness in identifying and quantifying synaptic puncta has not been characterized in detail. NEW ANALYSIS: We report on our assessment of the effectiveness of isolating punctate signals from diffusely distributed background noise using one variant of this approach, "Difference of Gaussian(s) (DoG)" which is based on a Gaussian filter. RESULTS: We evaluated immunocytochemically stained, cultured mouse hippocampal neurons as an example, and provided the rationale for choosing specific parameter values for individual steps in detecting glutamatergic nerve terminals. The intensity and width of the detected puncta were proportional to those obtained by manual fitting of two-dimensional Gaussian functions to the local information in the original image. COMPARISON WITH EXISTING METHODS: DoG was compared with the rolling-ball method, using biological data and numerical simulations. Both methods removed background noise, but differed slightly with respect to their efficiency in discriminating neighboring peaks, as well as their susceptibility to high-frequency noise and variability in object size. CONCLUSIONS: DoG will be useful in detecting punctate signals, once its characteristics are examined quantitatively by experimenters.


Assuntos
Imunofluorescência , Interpretação de Imagem Assistida por Computador , Neurônios/citologia , Distribuição Normal , Sinapses/metabolismo , Animais , Animais Recém-Nascidos , Células Cultivadas , Hipocampo/citologia , Camundongos , Microscopia Confocal , Proteínas Associadas aos Microtúbulos/metabolismo , Neurônios/metabolismo , Proteína Vesicular 1 de Transporte de Glutamato/metabolismo
12.
J Vis Exp ; (85)2014 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-24747983

RESUMO

Synaptic vesicles in functional nerve terminals undergo exocytosis and endocytosis. This synaptic vesicle recycling can be effectively analyzed using styryl FM dyes, which reveal membrane turnover. Conventional protocols for the use of FM dyes were designed for analyzing neurons following stimulated (evoked) synaptic activity. Recently, protocols have become available for analyzing the FM signals that accompany weaker synaptic activities, such as spontaneous or miniature synaptic events. Analysis of these small changes in FM signals requires that the imaging system is sufficiently sensitive to detect small changes in intensity, yet that artifactual changes of large amplitude are suppressed. Here we describe a protocol that can be applied to evoked, spontaneous, and miniature synaptic activities, and use cultured hippocampal neurons as an example. This protocol also incorporates a means of assessing the rate of photobleaching of FM dyes, as this is a significant source of artifacts when imaging small changes in intensity.


Assuntos
Pareamento Cromossômico/fisiologia , Corantes Fluorescentes/química , Compostos de Piridínio/química , Compostos de Amônio Quaternário/química , Vesículas Sinápticas/fisiologia , Animais , Camundongos , Fotodegradação , Terminações Pré-Sinápticas/química , Terminações Pré-Sinápticas/fisiologia , Ratos , Transmissão Sináptica/fisiologia , Vesículas Sinápticas/química
13.
Neurosci Lett ; 548: 61-6, 2013 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-23748075

RESUMO

Increased activities of cytoplasmic calcium and the excitatory neurotransmitter glutamate have been independently implicated in dystonia pathophysiology. However, cellular-level evidence linking these two features is not available. Here we show that glutamate-dependent changes in neuronal calcium dynamics occur in a knock-in mouse model of DYT1 dystonia, the most common hereditary form of this disorder. Fluorescence-based analysis of the dynamics of cytoplasmic calcium concentration ([Ca(2+)]c) in cultured hippocampal neurons shows that electrical stimulation depolarizes the neurons and increases the dendritic [Ca(2+)]c, which then decays slowly to the pre-stimulus level. Whereas the peak amplitude of [Ca(2+)]c was not affected, the decay period was prolonged in neurons of heterozygous mice whose genotype reflects the human condition. We found that this effect was blocked by the antagonists of ionotropic glutamate receptors, and confirmed that glutamate receptors are present in these neurons. As the [Ca(2+)]c is readout and regulator of neuronal excitability, its abnormality represents an important cellular phenotype of dystonia.


Assuntos
Sinalização do Cálcio , Cálcio/metabolismo , Citoplasma/metabolismo , Distonia/metabolismo , Hipocampo , Neurônios/metabolismo , Receptores de Glutamato/metabolismo , Animais , Células Cultivadas , Hipocampo/citologia , Hipocampo/metabolismo , Camundongos , Camundongos Knockout
14.
PLoS One ; 7(10): e48034, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23110166

RESUMO

The astrocyte is a major glial cell type of the brain, and plays key roles in the formation, maturation, stabilization and elimination of synapses. Thus, changes in astrocyte condition and age can influence information processing at synapses. However, whether and how aging astrocytes affect synaptic function and maturation have not yet been thoroughly investigated. Here, we show the effects of prolonged culture on the ability of astrocytes to induce synapse formation and to modify synaptic transmission, using cultured autaptic neurons. By 9 weeks in culture, astrocytes derived from the mouse cerebral cortex demonstrated increases in ß-galactosidase activity and glial fibrillary acidic protein (GFAP) expression, both of which are characteristic of aging and glial activation in vitro. Autaptic hippocampal neurons plated on these aging astrocytes showed a smaller amount of evoked release of the excitatory neurotransmitter glutamate, and a lower frequency of miniature release of glutamate, both of which were attributable to a reduction in the pool of readily releasable synaptic vesicles. Other features of synaptogenesis and synaptic transmission were retained, for example the ability to induce structural synapses, the presynaptic release probability, the fraction of functional presynaptic nerve terminals, and the ability to recruit functional AMPA and NMDA glutamate receptors to synapses. Thus the presence of aging astrocytes affects the efficiency of synaptic transmission. Given that the pool of readily releasable vesicles is also small at immature synapses, our results are consistent with astrocytic aging leading to retarded synapse maturation.


Assuntos
Astrócitos/fisiologia , Senescência Celular/fisiologia , Transmissão Sináptica/fisiologia , Vesículas Sinápticas/fisiologia , Animais , Animais Recém-Nascidos , Astrócitos/citologia , Astrócitos/metabolismo , Encéfalo/citologia , Encéfalo/metabolismo , Células Cultivadas , Técnicas de Cocultura , Potenciais Pós-Sinápticos Excitadores/fisiologia , Proteína Glial Fibrilar Ácida/metabolismo , Ácido Glutâmico/metabolismo , Imuno-Histoquímica , Camundongos , Camundongos Endogâmicos ICR , Microscopia Confocal , Neurônios/citologia , Neurônios/metabolismo , Neurônios/fisiologia , Técnicas de Patch-Clamp , Receptores de Glutamato/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismo , Vesículas Sinápticas/metabolismo , Fatores de Tempo , beta-Galactosidase/metabolismo
15.
Auris Nasus Larynx ; 36(2): 152-6, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18606508

RESUMO

OBJECTIVES: The aim of this study is to investigate the salicylate-induced morphological changes of cochlear inner hair cells (IHCs) and outer hair cells (OHCs). METHODS: IHCs and OHCs were acutely isolated from the guinea-pig cochlea. Cells were observed under the inverted microscope and 10mmol/L sodium salicylate solutions or 0.01mmol/L dexamethasone-plus-salicylate solutions were applied. The cell length or the ratio between the length and width was the indices of the morphological changes in cells. RESULTS: Isolated IHCs did not demonstrate any significant changes in sodium salicylate solutions in 20min and in 40min, whereas OHCs were shortened by the 10mmol/L sodium salicylate to 83% in 20min and 75% in 40min. There were no significant differences between in the dexamethasone-plus-salicylate solutions and in the control solutions after 20min and 40min both in IHCs and OHCs. CONCLUSIONS: Although salicylate affected the isolated OHCs from guinea-pig cochlea, IHCs were not changed morphologically by sodium salicylate applications. Dexamethasone inhibited the salicylate-induced morphological changes of OHCs.


Assuntos
Anti-Inflamatórios não Esteroides/toxicidade , Células Ciliadas Auditivas Internas/efeitos dos fármacos , Células Ciliadas Auditivas Externas/efeitos dos fármacos , Salicilato de Sódio/toxicidade , Animais , Tamanho Celular/efeitos dos fármacos , Cóclea/efeitos dos fármacos , Cóclea/patologia , Dexametasona/farmacologia , Cobaias , Células Ciliadas Auditivas Internas/patologia , Células Ciliadas Auditivas Externas/patologia , Técnicas In Vitro
16.
Artigo em Inglês | MEDLINE | ID: mdl-16446559

RESUMO

This study investigated hearing levels in cases of intractable otitis media with eosinophils and validated the treatment strategy. Medical charts were reviewed retrospectively. The diagnosis was made when the proportion of eosinophils in middle ear secretions exceeded 10%. Twelve patients were identified and treated with an antihistaminergic agent, leukotriene receptor antagonist and topical steroid. The air-bone conductance gap decreased significantly with the relief of subjective symptoms. Bone conduction hearing levels at 4 and 8 kHz were higher than at lower frequencies. There was a significant correlation between subjective symptom duration and bone conduction hearing level at 8 kHz, which diminished with treatment. Compared with suppurative otitis, active otitis with eosinophilia damages high-tone sensory hearing in a time-dependent manner, and antiallergic treatment prevents progression of the high-tone sensory hearing loss. We emphasize the importance of diagnosis and the validity of treatment for intractable otitis media with eosinophils.


Assuntos
Eosinofilia/diagnóstico , Eosinofilia/terapia , Otite Média com Derrame/diagnóstico , Otite Média com Derrame/terapia , Adulto , Audiometria de Tons Puros , Condução Óssea , Doença Crônica , Terapia Combinada , Progressão da Doença , Feminino , Perda Auditiva Neurossensorial/prevenção & controle , Humanos , Masculino , Pessoa de Meia-Idade , Análise de Regressão , Estudos Retrospectivos , Estatísticas não Paramétricas
17.
Folia Phoniatr Logop ; 57(3): 173-80, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15915000

RESUMO

It is generally accepted that, in glottic carcinoma, the voice will deteriorate, even in the early stages. This paper reports the degree of hoarseness and multidimensional vocal evaluation of glottic carcinoma patients. Forty-seven male glottic carcinoma patients and a control group of 13 normal subjects were included in this study involving psychoacoustic evaluation by doctors, acoustic analysis, phonogram, maximum phonation time and stroboscopy before treatment. A normal voice or mild hoarseness by psychoacoustic evaluation was found in 35% of cases with T1 and T2 glottic carcinoma. Patients with psychoacoustically inferior vocalization had high scores on acoustic analysis, small phonogram areas, and short maximum phonation time. Stroboscopy revealed attenuation or disappearance of the mucosal wave on the tumor side in all cases, whether the acoustic analysis data were within or beyond the normal limits. We identified two conditions offering superior vocalization in glottic carcinoma patients: (1) the lesion should be unilateral, and (2) the lesion should be flat with no protrusion. We should evaluate patients with glottic carcinoma not only with vocal examination but also using stroboscopy before biopsy.


Assuntos
Glote , Neoplasias Laríngeas/terapia , Fonação , Fonética , Acústica da Fala , Distúrbios da Voz/diagnóstico , Qualidade da Voz , Adulto , Idoso , Idoso de 80 Anos ou mais , Glote/patologia , Humanos , Neoplasias Laríngeas/diagnóstico , Neoplasias Laríngeas/patologia , Masculino , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Valores de Referência , Espectrografia do Som , Medida da Produção da Fala , Estroboscopia
18.
J Neurophysiol ; 87(4): 1694-702, 2002 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-11929891

RESUMO

Rat Meynert neurons were acutely isolated using a dissociation technique that maintains functional GABAergic presynaptic boutons. Miniature inhibitory postsynaptic currents (mIPSCs) were recorded under voltage-clamp conditions using whole cell patch-clamp recordings. Using the frequency of mIPSCs as a measure of presynaptic terminal excitability, the existence of a Na(+)/Ca(2+) exchanger (NCX) in these GABAergic nerve terminals was clearly demonstrated. Both the frequency and the amplitude of mIPSCs were unaffected by replacement of extracellular Na(2+). However, in this Na(+)-free external solution, ouabain could now induce a transient increase of mIPSCs frequency, which was not inhibited by adding Cd(2+) or cyclopiazonic acid but was inhibited by removing external Ca(2+). This indicates that this transient potentiation was dependent on external Ca(2+), but that this Ca(2+) influx was not via voltage-dependent Ca(2+) channels. KB-R7943, an inhibitor of NCX, at a concentration of 3 x 10(-6) M, reduced this transient increase of mIPSCs frequency without affecting mIPSCs amplitude and the response to exogenous GABA. These results demonstrate the existence of NCX in these GABAergic nerve terminals. In zero external Na(+), ouabain causes an accumulation of intraterminal Na(+) and a resultant influx of Ca(2+) through the reversed mode operation of NCX. However, under more physiological conditions, NCX may also operate in a forward mode and serve to maintain low intracellular [Ca(2+)] in nerve terminals.


Assuntos
Núcleo Basal de Meynert/metabolismo , Neurônios/metabolismo , Terminações Pré-Sinápticas/metabolismo , Trocador de Sódio e Cálcio/metabolismo , Ácido gama-Aminobutírico/metabolismo , Animais , Núcleo Basal de Meynert/citologia , Cálcio/farmacologia , Inibidores Enzimáticos/farmacologia , Inibição Neural/fisiologia , Ouabaína/farmacologia , Ratos , Ratos Wistar , Sódio/metabolismo , Sódio/farmacologia , Trocador de Sódio e Cálcio/fisiologia , Transmissão Sináptica/efeitos dos fármacos , Transmissão Sináptica/fisiologia
19.
Am J Physiol Endocrinol Metab ; 283(6): E1257-65, 2002 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-12424107

RESUMO

Gamma-aminobutyric acid (GABA)-mediated transmission in the medial preoptic area (MPOA) of the hypothalamus plays an important role in functions such as sex steroid hormone dynamics and control of body temperature. The action of allopregnanolone, the primary metabolite of progesterone, on GABAergic transmission was investigated by employing patch clamp whole cell recording on acutely dissociated rat MPOA neurons with the functional connection of presynaptic terminals. Allopregnanolone enhanced spontaneous GABA release on the MPOA neurons and induced prolonged decay of miniature GABAergic-inhibitory postsynaptic currents (mIPSCs). The facilitation of GABA release from the presynaptic terminals by allopregnanolone disappeared in Ca2+-free extracellular solution. The presynaptic action of this neurosteroid was also blocked by bumetanide, a blocker of cation-Cl- cotransporters, and by removal of extracellular Na+. The results suggest that allopregnanolone enhances GABAergic transmission at the MPOA neurons by pre- and postsynaptic mechanisms. The enhancement of GABA release by allopregnanolone might require a high Cl- concentration in the presynaptic terminal maintained by Na+-dependent, bumetanide-sensitive mechanisms (e.g., Na+-K+-Cl- cotransporter) and might be mediated by Ca2+ influx into presynaptic terminal.


Assuntos
Neurônios/efeitos dos fármacos , Pregnanolona/farmacologia , Área Pré-Óptica/efeitos dos fármacos , Transmissão Sináptica/efeitos dos fármacos , Ácido gama-Aminobutírico/metabolismo , Animais , Bumetanida/farmacologia , Cálcio/metabolismo , Separação Celular , Relação Dose-Resposta a Droga , Feminino , Técnicas In Vitro , Masculino , Neurônios/fisiologia , Técnicas de Patch-Clamp , Área Pré-Óptica/citologia , Área Pré-Óptica/fisiologia , Terminações Pré-Sinápticas/efeitos dos fármacos , Terminações Pré-Sinápticas/metabolismo , Ratos , Ratos Wistar , Sódio/metabolismo , Inibidores de Simportadores de Cloreto de Sódio e Potássio , Simportadores de Cloreto de Sódio-Potássio/metabolismo , Transmissão Sináptica/fisiologia
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