RESUMO
The ethidium bromide-demyelinating model (EB) was used to study remyelination in the brainstem under the use of cyclosporine (CsA). Wistar rats were submitted to intracisternal injection of 0.1% EB or 0.9% saline solution, and others were taken as histologic controls (group I). Within those injected with EB, some have not received immunosuppressive treatment (II); some were treated by intraperitonial route with CsA (III.E-10 mg/kg/day). Rats from group III.C were injected with saline solution and treated with CsA. The animals were perfused from 15 to 31 days post-injection collecting brainstem sections for light and transmission electron microscopy studies. After EB injection it was noted the presence of macrophages and non-degraded myelin debris, demyelinated axons, oligodendrocyte or Schwann cell remyelinated axons, groups of infiltrating pial cells, hypertrophic astrocytes and few lymphocytes. Tissue repair of EB-induced lesions in group III.E was similar to that of group II, but with the presence of a higher density of oligodendrocytes near remyelinating areas.
Assuntos
Tronco Encefálico/efeitos dos fármacos , Ciclosporina/uso terapêutico , Doenças Desmielinizantes/patologia , Imunossupressores/uso terapêutico , Neuroglia/ultraestrutura , Animais , Tronco Encefálico/citologia , Tronco Encefálico/fisiologia , Tronco Encefálico/ultraestrutura , Doenças Desmielinizantes/induzido quimicamente , Doenças Desmielinizantes/tratamento farmacológico , Doenças Desmielinizantes/fisiopatologia , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Etídio , Macrófagos/efeitos dos fármacos , Macrófagos/ultraestrutura , Masculino , Microscopia Eletrônica de Transmissão , Bainha de Mielina/efeitos dos fármacos , Bainha de Mielina/fisiologia , Neuroglia/efeitos dos fármacos , Neuroglia/fisiologia , Oligodendroglia/efeitos dos fármacos , Oligodendroglia/ultraestrutura , Ratos , Ratos Wistar , Células de Schwann/efeitos dos fármacos , Células de Schwann/ultraestruturaRESUMO
The ethidium bromide-demyelinating model (EB) was used to study remyelination in the brainstem under the use of cyclosporine (CsA). Wistar rats were submitted to intracisternal injection of 0.1 percent EB or 0.9 percent saline solution, and others were taken as histologic controls (group I). Within those injected with EB, some have not received immunosuppressive treatment (II); some were treated by intraperitonial route with CsA (III.E - 10 mg/kg/day). Rats from group III.C were injected with saline solution and treated with CsA. The animals were perfused from 15 to 31 days post-injection collecting brainstem sections for light and transmission electron microscopy studies. After EB injection it was noted the presence of macrophages and non-degraded myelin debris, demyelinated axons, oligodendrocyte or Schwann cell remyelinated axons, groups of infiltrating pial cells, hypertrophic astrocytes and few lymphocytes. Tissue repair of EB-induced lesions in group III.E was similar to that of group II, but with the presence of a higher density of oligodendrocytes near remyelinating areas.
Empregou-se o modelo desmielinizante do brometo de etídio (BE) com o objetivo de estudar a remielinização no tronco encefálico frente ao uso de ciclosporina (CsA). Foram utilizados ratos Wistar, submetidos à injeção de BE a 0,1 por cento ou de solução salina na cisterna pontina, assim como controles histológicos (grupo I). Dos animais injetados com BE, alguns não receberam tratamento imunossupressor (II); outros foram tratados por via intraperitoneal com CsA (III.E - 10 mg/kg/dia). O grupo III.C incluiu animais injetados com salina e tratados com CsA. Os animais foram perfundidos dos 15 aos 31 dias pós-injeção, com colheita de material do tronco encefálico para estudos de microscopia de luz e eletrônica de transmissão. Após injeção de BE, foram observados macrófagos e restos de mielina não-degradada, axônios desmielinizados ou remielinizados por oligodendrócitos e por células de Schwann, grupos de células piais infiltrantes, astrócitos hipertróficos e poucos linfócitos. O processo de reparo das lesões no grupo III.E apresentou-se similar ao do grupo II, porém com maior densidade de oligodendrócitos próximos às áreas de remielinização.
Assuntos
Animais , Masculino , Ratos , Tronco Encefálico/efeitos dos fármacos , Ciclosporina/uso terapêutico , Doenças Desmielinizantes/patologia , Imunossupressores/uso terapêutico , Neuroglia/ultraestrutura , Tronco Encefálico/citologia , Tronco Encefálico/fisiologia , Tronco Encefálico/ultraestrutura , Modelos Animais de Doenças , Avaliação Pré-Clínica de Medicamentos , Doenças Desmielinizantes/induzido quimicamente , Doenças Desmielinizantes/tratamento farmacológico , Doenças Desmielinizantes/fisiopatologia , Etídio , Microscopia Eletrônica de Transmissão , Macrófagos/efeitos dos fármacos , Macrófagos/ultraestrutura , Bainha de Mielina/efeitos dos fármacos , Bainha de Mielina/fisiologia , Neuroglia/efeitos dos fármacos , Neuroglia/fisiologia , Oligodendroglia/efeitos dos fármacos , Oligodendroglia/ultraestrutura , Ratos Wistar , Células de Schwann/efeitos dos fármacos , Células de Schwann/ultraestruturaRESUMO
Schwann cell disturbance followed by segmental demyelination in the peripheral nervous system occurs in diabetic patients. Since Schwann cell and oligodendrocyte remyelination in the central nervous system is a well-known event in the ethidium bromide (EB) demyelinating model, the aim of this investigation was to determine the behavior of both cell types after local EB injection into the brainstem of streptozotocin diabetic rats. Adult male Wistar rats received a single intravenous injection of streptozotocin (50 mg/kg) and were submitted 10 days later to a single injection of 10 microL 0.1% (w/v) EB or 0.9% saline solution into the cisterna pontis. Ten microliters of 0.1% EB was also injected into non-diabetic rats. The animals were anesthetized and perfused through the heart 7 to 31 days after EB or saline injection and brainstem sections were collected and processed for light and transmission electron microscopy. The final balance of myelin repair in diabetic and non-diabetic rats at 31 days was compared using a semi-quantitative method. Diabetic rats presented delayed macrophage activity and lesser remyelination compared to non-diabetic rats. Although oligodendrocytes were the major remyelinating cells in the brainstem, Schwann cells invaded EB-induced lesions, first appearing at 11 days in non-diabetic rats and by 15 days in diabetic rats. Results indicate that short-term streptozotocin-induced diabetes hindered both oligodendrocyte and Schwann cell remyelination (mean remyelination scores of 2.57 +/- 0.77 for oligodendrocytes and 0.67 +/- 0.5 for Schwann cells) compared to non-diabetic rats (3.27 +/- 0.85 and 1.38 +/- 0.81, respectively).
Assuntos
Tronco Encefálico/efeitos dos fármacos , Doenças Desmielinizantes/fisiopatologia , Diabetes Mellitus Experimental/fisiopatologia , Etídio/toxicidade , Bainha de Mielina/efeitos dos fármacos , Oligodendroglia/efeitos dos fármacos , Células de Schwann/efeitos dos fármacos , Animais , Tronco Encefálico/ultraestrutura , Doenças Desmielinizantes/induzido quimicamente , Masculino , Microscopia Eletrônica de Transmissão , Bainha de Mielina/fisiologia , Regeneração Nervosa/fisiologia , Oligodendroglia/fisiologia , Oligodendroglia/ultraestrutura , Ratos , Ratos Wistar , Células de Schwann/fisiologia , Células de Schwann/ultraestrutura , Fatores de TempoRESUMO
Schwann cell disturbance followed by segmental demyelination in the peripheral nervous system occurs in diabetic patients. Since Schwann cell and oligodendrocyte remyelination in the central nervous system is a well-known event in the ethidium bromide (EB) demyelinating model, the aim of this investigation was to determine the behavior of both cell types after local EB injection into the brainstem of streptozotocin diabetic rats. Adult male Wistar rats received a single intravenous injection of streptozotocin (50 mg/kg) and were submitted 10 days later to a single injection of 10 æL 0.1 percent (w/v) EB or 0.9 percent saline solution into the cisterna pontis. Ten microliters of 0.1 percent EB was also injected into non-diabetic rats. The animals were anesthetized and perfused through the heart 7 to 31 days after EB or saline injection and brainstem sections were collected and processed for light and transmission electron microscopy. The final balance of myelin repair in diabetic and non-diabetic rats at 31 days was compared using a semi-quantitative method. Diabetic rats presented delayed macrophage activity and lesser remyelination compared to non-diabetic rats. Although oligodendrocytes were the major remyelinating cells in the brainstem, Schwann cells invaded EB-induced lesions, first appearing at 11 days in non-diabetic rats and by 15 days in diabetic rats. Results indicate that short-term streptozotocin-induced diabetes hindered both oligodendrocyte and Schwann cell remyelination (mean remyelination scores of 2.57 ± 0.77 for oligodendrocytes and 0.67 ± 0.5 for Schwann cells) compared to non-diabetic rats (3.27 ± 0.85 and 1.38 ± 0.81, respectively).
Assuntos
Animais , Masculino , Ratos , Tronco Encefálico/efeitos dos fármacos , Doenças Desmielinizantes/fisiopatologia , Diabetes Mellitus Experimental/fisiopatologia , Etídio/toxicidade , Bainha de Mielina/efeitos dos fármacos , Oligodendroglia/efeitos dos fármacos , Células de Schwann/efeitos dos fármacos , Tronco Encefálico/ultraestrutura , Doenças Desmielinizantes/induzido quimicamente , Microscopia Eletrônica de Transmissão , Bainha de Mielina/fisiologia , Regeneração Nervosa/fisiologia , Oligodendroglia/fisiologia , Oligodendroglia/ultraestrutura , Ratos Wistar , Células de Schwann/fisiologia , Células de Schwann/ultraestrutura , Fatores de TempoRESUMO
Calcium channels of the P/Q subtype mediate transmitter release at the neuromuscular junction and at many central synapses, such as the calyx of Held. Transgenic mice in which alpha1A channels are ablated provide a powerful tool with which to test compensatory mechanisms at the synapse and to explore mechanisms of presynaptic regulation associated with expression of P/Q channels. Using the calyx of Held preparation from the knock-out (KO) mice, we show here that N-type channels functionally compensate for the absence of P/Q subunits at the calyx and evoke giant synaptic currents [approximately two-thirds of the magnitude of wild-type (WT) responses]. However, although evoked paired-pulse facilitation is prominent in WT, this facilitation is greatly diminished in the KO. In addition, direct recording of presynaptic calcium currents revealed that the major functional difference was the absence of calcium-dependent facilitation at the calyx in the P/Q KO animals. We conclude that one physiological function of P/Q channels is to provide additional facilitatory drive, so contributing to maintenance of transmission as vesicles are depleted during high throughput synaptic transmission.
Assuntos
Canais de Cálcio Tipo N/fisiologia , Canais de Cálcio Tipo P/fisiologia , Canais de Cálcio Tipo Q/fisiologia , Sinapses/fisiologia , Animais , Tronco Encefálico/fisiologia , Tronco Encefálico/ultraestrutura , Cálcio/fisiologia , Canais de Cálcio Tipo N/genética , Canais de Cálcio Tipo P/genética , Canais de Cálcio Tipo Q/genética , Potenciais Evocados , Técnicas In Vitro , Camundongos , Camundongos Knockout , Plasticidade Neuronal , Terminações Pré-Sinápticas/fisiologia , Subunidades Proteicas/genética , Subunidades Proteicas/fisiologia , Transmissão SinápticaRESUMO
Lymphocytes are present within ethidium-bromide (EB)-demyelinated lesions in the central nervous system (CNS) and the possibility of its participation in accidental immune-mediated responses to the detached myelin sheaths can not be ruled out. This study aimed to investigate the consequences of immunosuppression with dexamethasone in CNS repair after local EB injection. Adult Wistar rats received 10 microlitres of 0.1% EB solution into the cisterna pontis. Some were treated intraperitoneally with dexamethasone (3 mg/kg/day, group I, n=15) during the experimental period; others were not immunosuppressed (group II, n=15). Animals from both groups were perfused with 4% glutharaldehyde at 7,11,15,21 and 31 days following EB injection. Brainstem slices were collected and processed for transmission electron microscopy studies. Rats from group I showed greater amounts of myelin-derived membranes than non-immunosuppressed rats (group II), suggesting a delay in the macrophagic activity of removing myelin debris. Rare lymphocytes were found. Oligodendrocyte remyelinating activity also showed a delayed pattern, with clear predominance of naked axons.
Assuntos
Anti-Inflamatórios/farmacologia , Tronco Encefálico/ultraestrutura , Doenças Desmielinizantes/patologia , Dexametasona/farmacologia , Bainha de Mielina/ultraestrutura , Animais , Tronco Encefálico/efeitos dos fármacos , Doenças Desmielinizantes/tratamento farmacológico , Modelos Animais de Doenças , Etídio , Terapia de Imunossupressão , Masculino , Microscopia Eletrônica de Varredura , Bainha de Mielina/efeitos dos fármacos , Bainha de Mielina/fisiologia , Regeneração Nervosa/efeitos dos fármacos , Ratos , Ratos Wistar , Fatores de TempoRESUMO
Long-term cyclophosphamide (CY) treatment was used in male Wistar rats submitted to ethidium bromide (EB) demyelinating model to investigate ultrastructurally the drug effects on remyelination and on central nervous system (CNS) tissue repair. Demyelination was induced by a single 10 microl intracisternal injection of 0.1% EB solution and the rats anaesthetized and perfused through the heart from the 15th to the 31st day after injection. Brainstem sections were collected and processed for light and transmission electron microscopy studies. At different times after EB injection, it was observed the presence of macrophages in phagocytic activity and non-degraded myelin debris in the extracellular space, as well as remyelinated and demyelinated axons. Remyelination was carried out by both oligodendrocytes and Schwann cells, the latter notably around blood vessels and in areas of expanded extracellular space. It was also noted groups of infiltrating meningeal cells and astrocytes showing hypertrophic processes with numerous bundles of glial filaments. The rats treated with CY showed greater amounts of myelin-derived membranes than non-treated rats, suggesting a delay in the macrophage activity of removing myelin debris. Additionally oligodendrocyte remyelinating activity showed an incipient and restricted pattern, with clear predominance of naked axons. Rare lymphocytes were also found, as well as decreased neovascularization.
Assuntos
Tronco Encefálico/efeitos dos fármacos , Tronco Encefálico/ultraestrutura , Ciclofosfamida/farmacologia , Etídio/toxicidade , Imunossupressores/farmacologia , Bainha de Mielina/efeitos dos fármacos , Bainha de Mielina/ultraestrutura , Animais , Doenças Desmielinizantes/tratamento farmacológico , Doenças Desmielinizantes/patologia , Macrófagos/efeitos dos fármacos , Macrófagos/ultraestrutura , Masculino , Microscopia Eletrônica , Ratos , Ratos WistarRESUMO
Our frog brainstem preparation revealed mechanisms for the central control of breathing that are in many ways similar to those of mammals. Thus, the basic control mechanisms for air-breathing appear to have been present in the Devonian common ancestors of frogs and mammals and may be common to all lung-breathing vertebrates. Location: The in vitro frog brainstem, including motor nuclei of cranial nerves V to X, maintains frequency and ratio of fictive buccal oscillations to fictive lung inflation episodes comparable with that of the living animal. In this preparation, transaction caudal to V abolishes spontaneous discharge in X but slow, spontaneous discharge in V may remain. Independent central pattern generation is present in the left and right half-brainstems. Chemosensitivity: The frequency of fictive lung inflation increases with decrease in pH within the physiological range. Response to glutamate: Biphasic response, consisting of a pause, followed by a dramatic increase in the frequency of fictive inspirations and positive baseline deflection, followed, in turn, by slow return of the baseline to the control level with frequency remaining above control as long as glutamate is applied. Local application reveals glutamate-sensitive sites in the ventral reticular formation. Response to substance P and physalaemin: Similar to glutamate but the frequency of fictive inspirations decreases below control values. Response to strychnine: The normal temporal sequence in firing of motor neurons of cranial nerves is disrupted and all nerves are synchronously active. The firing sequence of respiratory neurons is consistent with a grouping possibly homologous to the mammalian inspiratory, post-inspiratory and expiratory phases.
Assuntos
Animais , Anuros/fisiologia , Tronco Encefálico/ultraestrutura , Técnicas In Vitro , Respiração/fisiologia , Ácido Glutâmico/farmacologia , Estricnina/farmacologia , Substância P/farmacologiaRESUMO
Our frog brainstem preparation revealed mechanisms for the central control of breathing that are in many ways similar to those of mammals. Thus, the basic control mechanisms for air-breathing appear to have been present in the Devonian common ancestors of frogs and mammals and may be common to all lung-breathing vertebrates. LOCATION: The in vitro frog brainstem, including motor nuclei of cranial nerves V to X, maintains frequency and ratio of fictive buccal oscillations to fictive lung inflation episodes comparable with that of the living animal. In this preparation, transection caudal to V abolishes spontaneous discharge in X but slow, spontaneous discharge in V may remain. Independent central pattern generation is present in the left and right half-brainstems. CHEMOSENSITIVITY: The frequency of fictive lung inflations increases with decrease in pH within the physiological range. RESPONSE TO GLUTAMATE: Biphasic response, consisting of a pause, followed by a dramatic increase in the frequency of fictive inspirations and positive baseline deflection, followed, in turn, by slow return of the baseline to the control level with frequency remaining above control as long as glutamate is applied. Local application reveals glutamate-sensitive sites in the ventral reticular formation. RESPONSE TO SUBSTANCE P AND PHYSALAEMIN: Similar to glutamate but the frequency of fictive inspirations decreases below control values. RESPONSE TO STRYCHNINE: The normal temporal sequence in firing of motor neurons of cranial nerves is disrupted and all nerves are synchronously active. The firing sequence of respiratory neurons is consistent with a grouping possibly homologous to the mammalian inspiratory, post-inspiratory and expiratory phases.
Assuntos
Anuros/fisiologia , Respiração/fisiologia , Animais , Tronco Encefálico/ultraestrutura , Ácido Glutâmico/farmacologia , Técnicas In Vitro , Estricnina/farmacologia , Substância P/farmacologiaRESUMO
Se examinaron los cerebros de tres niños fallecidos con diagnóstico de síndrome de muerte súbita infantil (SMSI), con el propósito de determinar el patrón de maduración histológico de los núcleos del puente, oliva bulbar e hipogloso mayor, núcleos del tonco encefálico que no están directamente vinculados con la función cardiorrespiratoria y compararla con el patrón observado en tres niños que fallecieron de causa conocida usando el método de Golgi-Cox y morfometria. Los niños fallecidos del SMSI presentan una reducción significativa de la arborización dendrítica neural en los tres núcleos estudiados, comparado con el grupo control. Estos hallazgos sugieron un retardo de la maduración neuronal de todo el tronco encefálico y no sólo de los centros cardiorrespiratorios como ha sido demostrado en niños que fallecieron del SMSI. Se sugiere que este retardo en la maduración del tronco encefálico representa un sustrato anatómico anormal en la multifactorial patogénesis de este síndrome
Assuntos
Humanos , Masculino , Feminino , Recém-Nascido , Ângulo Cerebelopontino/crescimento & desenvolvimento , Tronco Encefálico/ultraestrutura , Dendritos/ultraestrutura , Nervo Hipoglosso/crescimento & desenvolvimento , Morte Súbita do Lactente/etiologia , Núcleo Olivar/crescimento & desenvolvimentoRESUMO
Ultrastructural cerebrospinal fluid of 20 parkinsonian patients examined by negative staining showed not recognizable structures thought to be of viral origin in 6 cases (30%). However, mortality rate analysis failed to disclose significant differences between the inoculated animals. Either artefact or not, such structures deserve to be reported.
Assuntos
Tronco Encefálico/ultraestrutura , Neurônios/ultraestrutura , Doença de Parkinson/líquido cefalorraquidiano , Feminino , Humanos , Masculino , Microscopia Eletrônica , Doença de Parkinson/microbiologia , Coloração e Rotulagem/métodosRESUMO
Pelo método da coloraçäo negativa, o estudo ultra-estrutural do líquido cefalorraquiano, em 20 casos de parkinsonismo, mostrou presença de estruturas näo-identificadas, com configuraçöes geométricas, em 30%. Consideradas como suspeitas de conterem partículas virais, por questäo de método, näo levaram a dados estatisticamente significativos se comparados à incidência de mortalidade entre os animais de experimentaçäo. Artefatos ou näo, estas estruturas merecem registro
Assuntos
Humanos , Masculino , Feminino , Tronco Encefálico/ultraestrutura , Doença de Parkinson/líquido cefalorraquidiano , Neurônios/ultraestrutura , Líquido Cefalorraquidiano/microbiologia , Doença de Parkinson/etiologia , Coloração e RotulagemRESUMO
The synaptogenesis and the morphological differentiation of neural cells were studied in aggregating cultures. Brainstems of 14-15 days old rat embryos were removed and the area located between the mesencephalic flexure and the caudal portion of metencephalon was dissected and mechanically dissociated to single cells. These cells reassociated forming highly organized aggregates in which differentiation took place. Samples were harvested after different time periods, fixed and processed for electron-microscopic study. After one day in culture the aggregates were composed by rounded undifferentiated cells. These cells had a high nuclear/cytoplasmic relation, were devoid of processes and were separated by great intercellular spaces. At the end of the first week of culture cell differentiation and extension of processes were evident. A loose neuropil appeared: it was composed by abundant growing neurites and growth cones. Later, the neuropil became more compact and glial processes and synaptic terminals filled with vesicles appeared. The early appearance of vesicles in the synaptic endings was the first evidence of synaptogenesis. Post and presynaptic membrane densities appeared later, and fully mature synaptic contacts were seen by the end of the 3rd week in culture. Scarce myelin sheaths were observed after 35 days in vitro.
Assuntos
Tronco Encefálico/ultraestrutura , Animais , Tronco Encefálico/embriologia , Agregação Celular , Diferenciação Celular , Células Cultivadas , Microscopia Eletrônica , Bainha de Mielina/ultraestrutura , Ratos , Ratos Endogâmicos/embriologia , Sinapses/ultraestruturaRESUMO
A light and electronmicroscopic immunocytochemical study of the glial cells in the brainstem and spinal cord of the 18th day rat embryo was performed using an anti-S-100 protein antiserum. Only the radial glia and the free immature glial cells are S-100 immunoreactive. Neurons are devoid of S-100 immunoreactivity. The radial glia form two paramedial plates and a great number of lateral plates, uniformly spaced along the ventral portion of the brainstem from the mesencephalon to the medulla. The S-100 protein was also detected in the perivascular membranes and glial limitans. Embryonic glia adopt a highly organized spatial pattern in the brainstem that could set the structural basis for an organized assembly of the developing nervous tissue. The use of the S-100 protein as a glial marker in the embryonic rat brain proved to be of great value. Antibodies to S-100 protein allow the demonstration of immature glial cells and a highly organized spatial pattern in the brainstem and spinal cord of the rat embryo.
Assuntos
Tronco Encefálico/metabolismo , Neuroglia/metabolismo , Proteínas S100/metabolismo , Medula Espinal/metabolismo , Animais , Tronco Encefálico/embriologia , Tronco Encefálico/ultraestrutura , Feminino , Imuno-Histoquímica , Neuroglia/ultraestrutura , Ratos , Ratos Endogâmicos , Medula Espinal/embriologia , Medula Espinal/ultraestruturaRESUMO
The synaptogenesis and the morphological differentiation of neural cells were studied in aggregating cultures. Brainstems of 14-15 days old rat embryos were removed and the area located between the mesencephalic flexure and the caudal portion of metencephalon was dissected and mechanically dissociated to single cells. These cells reassociated forming highly organized aggregates in which differentiation took place. Samples were harvested after different time periods, fixed and processed for electron-microscopic study. After one day in culture the aggregates were composed by rounded undifferentiated cells. These cells had a high nuclear/cytoplasmic relation, were devoid of processes and were separated by great intercellular spaces. At the end of the first week of culture cell differentiation and extension of processes were evident. A loose neuropil appeared: it was composed by abundant growing neurites and growth cones. Later, the neuropil became more compact and glial processes and synaptic terminals filled with vesicles appeared. The early appearance of vesicles in the synaptic endings was the first evidence of synaptogenesis. Post and presynaptic membrane densities appeared later, and fully mature synaptic contacts were seen by the end of the 3rd week in culture. Scarce myelin sheaths were observed after 35 days in vitro
Assuntos
Animais , Ratos , Tronco Encefálico/ultraestrutura , Tronco Encefálico/embriologia , Agregação Celular , Diferenciação Celular , Células Cultivadas , Microscopia Eletrônica , Bainha de Mielina/ultraestrutura , Ratos Endogâmicos/embriologia , Sinapses/ultraestruturaRESUMO
The synaptogenesis and the morphological differentiation of neural cells were studied in aggregating cultures. Brainstems of 14-15 days old rat embryos were removed and the area located between the mesencephalic flexure and the caudal portion of metencephalon was dissected and mechanically dissociated to single cells. These cells reassociated forming highly organized aggregates in which differentiation took place. Samples were harvested after different time periods, fixed and processed for electron-microscopic study. After one day in culture the aggregates were composed by rounded undifferentiated cells. These cells had a high nuclear/cytoplasmic relation, were devoid of processes and were separated by great intercellular spaces. At the end of the first week of culture cell differentiation and extension of processes were evident. A loose neuropil appeared: it was composed by abundant growing neurites and growth cones. Later, the neuropil became more compact and glial processes and synaptic terminals filled with vesicles appeared. The early appearance of vesicles in the synaptic endings was the first evidence of synaptogenesis. Post and presynaptic membrane densities appeared later, and fully mature synaptic contacts were seen by the end of the 3rd week in culture. Scarce myelin sheaths were observed after 35 days in vitro (AU)
Assuntos
Animais , Ratos , Tronco Encefálico/ultraestrutura , Agregação Celular , Diferenciação Celular , Microscopia Eletrônica , Ratos Endogâmicos/embriologia , Sinapses/ultraestrutura , Bainha de Mielina/ultraestrutura , Tronco Encefálico/embriologia , Células CultivadasRESUMO
C3H mice infected intravenously with the JHM strain of coronavirus showed high incidence of demyelination (44.8%) and low incidence of encephalitis-induced mortality (6.9%). High titers of virus were detectable in the brain and liver of mice only during the first 3 to 12 days of infection (10(3) and 10(4) PFU/g, respectively). Most of the animals recovered from the first phase of disease and some (11.1%) came down with paralysis 6 to 7 weeks after the infection, with no histological changes or virus detectable in their tissues.
Assuntos
Infecções por Coronaviridae/complicações , Doenças Desmielinizantes/etiologia , Encefalomielite/etiologia , Animais , Tronco Encefálico/ultraestrutura , Coronaviridae/patogenicidade , Camundongos , Camundongos Endogâmicos C3HRESUMO
C3H mice infected intravenously with the JHM strain of coronavirus showed high incidence of demyelination (44.8%) and low incidence of encephalitis-induced mortality (6.9%). High titers of virus were detectable in the brain and liver of mice only during the first 3 to 12 days of infection (10 and 10 PFU/g, respectively). Most of the animals recovered from the first phase of disease and some (1.1%) came down with paralysis 6 to 7 weeks after the infection, with no histological changes or virus detectable in their tissues
Assuntos
Camundongos , Animais , Coronaviridae/patogenicidade , Infecções por Coronavirus/complicações , Doenças Desmielinizantes/etiologia , Encefalomielite/etiologia , Tronco Encefálico/ultraestrutura , Camundongos Endogâmicos C3H , Ativação ViralRESUMO
É apresentado um caso autopsiado de encefalite herpética do tronco encefalico. Clinicamente o paciente apresentou de início cefaléia, seguida de ataxia, sonolência e paralisias múltiplas de alguns nervos cranianos, evoluindo para a morte em 8 dias. O exame anatomopatológico do encéfalo mostrou encefalite necrosante em focos múltiplos limitada ao tronco encefálico, mais acentuada na ponte e bulbo. A técnica da imunoperoxidase revelou raras células gliais com imunorreatividade intranuclear para antígeno do herpes. Raras partículas virais com as características morfológicas do herpesvírus foram identificadas nos núcleos de células nervosas em material fixado em formol a 10%. Este caso é o segundo relatado de encefalite herpética do tronco do encéfalo confirmado pelo exame anatomopatológico. Comentam-se as vias de chegada do herpesvírus ao sistema nervoso central e sua posterior disseminaçäo, após período de latência e reativaçäo, para a cavidade oral, regiäo órbito-frontal, lobos temporais e tronco encefálico