Expressão da proteína nestina no cérebro de ratos submetidos ao status epilepticus induzido pela pilocarpina: avaliação do período pós-natal ao envelhecimento
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Data
2006
Autores
Scorza, Carla Alessandra [UNIFESP]
Orientadores
Naffah-Mazzacoratti, Maria da Graca [UNIFESP]
Tipo
Tese de doutorado
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Objetivos: A nestina, uma proteína do filamento intermediário, pode ser usada como um indicador de imaturidade celular. Nas células já diferenciadas, essa proteína é substituída por outro tipo de filamento intermediário, específico do referido tecido. Porém, sua reexpressão pode ser induzida em condições regenerativas e/ou degenerativas. Assim, na tentativa de elucidar as alterações plásticas após um dano cerebral provocado pelo status epilepticus (SE) induzido pela pilocarpina em ratos, nossos objetivos foram: Ia) Estudar a expressão fisiológica normal da nestina no hipocampo e no córtex de ratos normais desde PN9 até a fase adulta (PN90); Ib) Avaliar as alterações da expressão da nestina no hipocampo e no córtex de ratos submetidos a três episódios de SE, induzidos pela pilocarpina, em PN7 PN8 e PN9. Esses animais foram estudados desde PN9 até PN90; 11) Estudar a expressão temporal e espacial da nestina no hipocampo de ratos adultos submetidos ao modelo da pilocarpina (fases aguda, silenciosa e crônica); 111) Avaliar a expressão da nestina no hipocampo de ratos idosos normais e em ratos idosos com epilepsia. Esses animais foram submetidos ao modelo da pilocarpina na fase adulta e seus cérebros foram estudados ao completarem dois anos de idade. Métodos: Indução do SE pela injeção de pilocarpina (ip); a expressão da nestina foi estudada por imuno-histoquímica. Resultados: No período pós-natal precoce, a expressão fisiológica da nestina foi intensamente visualizada nas glias radiais corticais, nas fibras hipocampais e nos vasos sanguíneos, desaparecendo nos animais adultos. Os animais submetidos ao SE em PN7-9, apresentaram aumento na expressão e atraso no desaparecimento da nestina, tanto nas glias radiais como nos vasos sanguíneos, em relação aos seus respectivos controles. Glias radiais corticais foram ainda encontradas nos ratos experimentais em PN21, enquanto que durante o desenvolvimento fisiológico normal elas já não estão mais presentes nessa idade. Quanto à distribuição temporal e espacial da nestina nos astrócitos reativos hipocampais de ratos adultos, submetidos ao modelo da pilocarpina, não encontramos a expressão dessa proteína nos animais dos grupos controle e agudo. Em contraste, os ratos...(au).
Purpose: Nestin is an intermediate filament component protein and can be used as an indicator of cellular immaturity. In the adult differentiated cell, nestin is replaced for other intermediate filament protein specific of the referred tissue. However, nestin re-expression can be induced by regenerative and/or degenerative conditions. In this way, in order to try to elucidate the plastic alterations followed by brain damage provoked by status epilepticus (SE) induced by pilocarpine in rats, the present work has the following purposes: Ia) Evaluate the physiological hippocampal and cortical nestin expression in rats from P9 to adulthood (P90); Ib) Evaluate hippocampal and cortical alterations of nestin expression in rats submitted to three episodes of SE induced by pilocarpine (P7,P8,P9). These animals were studied from P9 to P90; II) Evaluate the hippocampal temporal and spatial nestin expression of the adult rats submitted to the pilocarpine model of epilepsy (acute, silent and chronic phases); III) Evaluate the hippocampal nestin expression in aged normal rats and in aged rats with epilepsy. The aged chronic rats were submitted to the pilocarpine SE when young adults and they were studied with two years old. Methods: The SE was induced by pilocarpine injection (ip) and nestin expression was studied by immunohistochemistry. Results: Nestin expression was found in cortical radial glia, hippocampal fibers and blood vessels during early postnatal development, disappearing in the adulthood. Rats submitted to pilocarpine SE (P7-P9) showed a delayed nestin down-regulation in the cortical radial glia as well as in the blood vessels, when compared to their controls. We still found cortical radial glia in the experimental rats of P21 group, however they are not found anymore under normal physiological conditions at this age. Referring to the hippocampal reactive astrocytes expressing nestin in the adult rats submitted to the pilocarpine model, we did not detect nestin expression in the rats of the control and acute groups. In other hand, the animals of the silent group presented intense nestin expression 3 and 7 days after SE. Interestingly, still in the silent phase, we did not find any nestin expression 14 days after SE. However, in the 65 chronic phase of the model, the reactive astrocytes expressing nestin are again observed and they were sparsely distributed for all the hippocampal formation. The aged rats of the control group did not present nestin expression. However, aged chronic rats presenting long term epilepsy showed the same pattern of nestin immunoreactivity as observed in the chronic adult rats. Conclusions: This work showed that physiological nestin expression during early postnatal development to adulthood. Nestin immunoreactivity was intense in the cortical radial glia, hippocampal fibers and blood vessels during the early postnatal development disapearing in adulthood. Our data shoed that nestin expression was delayed in the rats submitted to SE (P7-9), suggesting a normal development impairment. We still found cortical radial glia in P21 in the experimental animals, suggesting a retardation of nestin down-regulation. The adult rats of the silent phase of the pilocarpine model presented transient nestin expression in the reactive astrocytes. However, reactive astrocytes expressing nestin were still found in the chronic phase of the model. These data suggest that nestin plays a role in the plastic events in the adult tissue after brain damage. The normal aging did not induce nestin re-expression. However, aged rats have the potential to re-express a developmental protein of immature cell, since the chronic aged rats in this study presented hippocampal reactive astrocytes. In this way, the knowledge of a temporal window of proteins such as nestin, with multi-potential and regenerative potential, allows advances in neurobiology understanding and contributes to the progress of cellular therapy in neurological diseases.
Purpose: Nestin is an intermediate filament component protein and can be used as an indicator of cellular immaturity. In the adult differentiated cell, nestin is replaced for other intermediate filament protein specific of the referred tissue. However, nestin re-expression can be induced by regenerative and/or degenerative conditions. In this way, in order to try to elucidate the plastic alterations followed by brain damage provoked by status epilepticus (SE) induced by pilocarpine in rats, the present work has the following purposes: Ia) Evaluate the physiological hippocampal and cortical nestin expression in rats from P9 to adulthood (P90); Ib) Evaluate hippocampal and cortical alterations of nestin expression in rats submitted to three episodes of SE induced by pilocarpine (P7,P8,P9). These animals were studied from P9 to P90; II) Evaluate the hippocampal temporal and spatial nestin expression of the adult rats submitted to the pilocarpine model of epilepsy (acute, silent and chronic phases); III) Evaluate the hippocampal nestin expression in aged normal rats and in aged rats with epilepsy. The aged chronic rats were submitted to the pilocarpine SE when young adults and they were studied with two years old. Methods: The SE was induced by pilocarpine injection (ip) and nestin expression was studied by immunohistochemistry. Results: Nestin expression was found in cortical radial glia, hippocampal fibers and blood vessels during early postnatal development, disappearing in the adulthood. Rats submitted to pilocarpine SE (P7-P9) showed a delayed nestin down-regulation in the cortical radial glia as well as in the blood vessels, when compared to their controls. We still found cortical radial glia in the experimental rats of P21 group, however they are not found anymore under normal physiological conditions at this age. Referring to the hippocampal reactive astrocytes expressing nestin in the adult rats submitted to the pilocarpine model, we did not detect nestin expression in the rats of the control and acute groups. In other hand, the animals of the silent group presented intense nestin expression 3 and 7 days after SE. Interestingly, still in the silent phase, we did not find any nestin expression 14 days after SE. However, in the 65 chronic phase of the model, the reactive astrocytes expressing nestin are again observed and they were sparsely distributed for all the hippocampal formation. The aged rats of the control group did not present nestin expression. However, aged chronic rats presenting long term epilepsy showed the same pattern of nestin immunoreactivity as observed in the chronic adult rats. Conclusions: This work showed that physiological nestin expression during early postnatal development to adulthood. Nestin immunoreactivity was intense in the cortical radial glia, hippocampal fibers and blood vessels during the early postnatal development disapearing in adulthood. Our data shoed that nestin expression was delayed in the rats submitted to SE (P7-9), suggesting a normal development impairment. We still found cortical radial glia in P21 in the experimental animals, suggesting a retardation of nestin down-regulation. The adult rats of the silent phase of the pilocarpine model presented transient nestin expression in the reactive astrocytes. However, reactive astrocytes expressing nestin were still found in the chronic phase of the model. These data suggest that nestin plays a role in the plastic events in the adult tissue after brain damage. The normal aging did not induce nestin re-expression. However, aged rats have the potential to re-express a developmental protein of immature cell, since the chronic aged rats in this study presented hippocampal reactive astrocytes. In this way, the knowledge of a temporal window of proteins such as nestin, with multi-potential and regenerative potential, allows advances in neurobiology understanding and contributes to the progress of cellular therapy in neurological diseases.
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Citação
SCORZA, Carla Alessandra. Expressão da proteína nestina no cérebro de ratos submetidos ao status epilepticus induzido pela pilocarpina: avaliação do período pós-natal ao envelhecimento. 2006. 98 p. Tese (Doutorado em Ciências) - Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, 2006.