Ultrastructural study of the effects of cyclosporine in the brainstem of Wistar rats submitted to the ethidium bromide demyelinating model / Estudo ultra-estrutural dos efeitos da ciclosporina no tronco encefálico de ratos Wistar submetidos ao modelo desmielinizante do brometo de etídio

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.

Delayed Schwann cell and oligodendrocyte remyelination after ethidium bromide injection in the brainstem of Wistar rats submitted to streptozotocin diabetogenic treatment

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).

The frog brainstem preparation as a model for studying the central control of breathing in tetrapods

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.

Maduración histológica de las neuronas del tronco encefálico en víctimas del síndrome de muerte súbita infantil / Histological maturation of the neurons of the brainstem in victims of sudden death syndrome of children

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

Análise ultra-estrutural do líquido cefalorraquiano de parkinsonianos / Ultrastructural analysis of the cerebrospinal fluid of patients with Parkinson disease

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

Ultrastructural study of reaggregated culture of brainstem: synaptogenesis

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

Nonfatal demyelinating encephalomyelitis induced by coronavirus (JHM strain) infection in mice

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

Encefalite herpética do tronco encefálico: relato de um caso autopsiado com estudo imuno-histoquímico e ao microscópio eletrônico / Herpetic brain stem encephalitis: report of an autopsied case with immunohistochemical and electron microscopy study

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