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Previous issue date: 2013 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Associação Fundo de Incentivo à Psicofarmacologia (AFIP) / Diversos estudos sugerem a existência de múltiplos sistemas de memória, que interagem entre si, de forma competitiva ou comparativa. Existem evidências de que os processos de aprendizagem e memória dependem da integridade do hipocampo, estriado e córtex pré-frontal. Já foi demonstrado que essas três estruturas estão envolvidas com o condicionamento de medo, uma tarefa comportamental que avalia a memória. Durante o treino da tarefa de condicionamento de medo, utiliza-se um choque nas patas que pode ser pareado com o ambiente (contexto foreground; CMC) ou com um estímulo discreto, como um som (nesse caso, o condicionamento do contexto fica em segundo plano, chamado de contexto background; CMS). Outra maneira de se estudar a memória é por meio da biologia molecular, estudando genes relacionados a plasticidade neural, como os genes de expressão imediata. No entanto, o papel do estriado no condicionamento de medo ao som (CMS) ainda não totalmente esclarecido. Nosso objetivos foi avaliar a expressão dos genes de expressão imediata após uma tarefa de memória no estriado. No presente estudo, o hipocampo foi inativado com AP-5 a fim de se verificar a possível interação entre estruturas cerebrais, através da análise dos genes de expressão imediata (IEGs) c-fos, Egr-1 e Arc no hipocampo, estriado e córtex pré-frontal após o treino da tarefa de CMS. Na primeira etapa do estudo, foi possível observar que o AP-5 causou um prejuízo no CMC, mas não no CMS. Na segunda etapa do estudo, verificamos a expressão gênica (por meio da técnica de PCR em tempo real) e protéica (por meio da técnica de westen blot) dos IEGS 30 e 90 minutos após o treino do CMS. Quando o CMS fosse realizado e o hipocampo estivesse inativado com AP-5, era de se esperar que a participação contextual fosse menor; assim, a participação do estriado nesse tipo de condicionamento poderia ser melhor estudada. No entanto, os nossos dados sugerem que a administração de AP-5 no hipocampo não interfere com a expressão proteica de c-fos, egr1 e arc no estriado, já que os grupos de animais que receberam AP-5 são iguais aos seus grupos controles que receberam salina. Além disso, a administração de AP-5 diretamente no hipocampo aumentou a expressão gênica dos IEGs 30 minutos depois da tarefa. Por fim, os dados mostram que os grupos que receberam o pareamento e o grupo só exposto ao ambiente apresentam uma menor expressão protéica relativa de EGR1 quando comparado aos animais que só receberam a administração de droga. Uma menor expressão dos IEGs pode estar relacionada com o funcionamento da via neuroanatômica do estriado, relacionado com o padrão de ativação dos neurônios dopaminérgicos, que modificaria a plasticidade sináptica no estriado. O presente estudo mostra como as estruturas relacionadas à memória e à aprendizagem, como o estriado e córtex pré-frontal estão envolvidas na tarefa do condicionamento de medo ao som. / Several studies suggest the existence of multiple memory systems that interact in a competitive or comparative way. There are evidences that the processes of learning and memory depend on the integrity of the regions of the hippocampus, striatum and prefrontal cortex. It has been shown that these three structures are involved in fear conditioning, a task that evaluates emotional memory. During the training of fear conditioning task, a footshock can be paired with the environment (context foreground; CFC) or a cued stimulus such as a sound (in this case, the conditioning of the context is secondary, called contextual background; TFC). This memory can also be evaluated by techniques of molecular biology, studying genes involved in neural plasticity, such as the expression of immediate early genes (IEGs). Our hypothesis was to evaluate the expression of IEGs after an aversive memory task. In the present study, the hippocampus was inactivated with administration of AP-5, a glutamate antagonist, in order to verify the possible interaction between these brain structures by analyzing the IEGs c-fos, Egr1 and Arc in the hippocampus, prefrontal cortex and striatum after TFC training task. In the first part of the study, it was observed that the AP-5 impairs CFC, but not TFC. In the second part of the study, we evaluated gene expression (by real-time PCR) and protein expression (by Western blot) of IEGs 30 and 90 minutes after TFC training. When TFC was performed and the hippocampus was inactivated with AP-5, it was expected a lesser contextual participation, so the participation of the striatum in this type of conditioning could be better studied. However, our data suggests that administration of AP-5 in the hippocampus do not interfere with the expression of c-fos, Egr1 and Arc in striatum, hippocampus and prefrontal cortex, since groups of animals that received AP-5 have similar expression when compared to control groups that received saline. Furthermore, administration of AP-5 directly in the hippocampus increased gene expression of IEGs in this structure 30 minutes after TFC training. Finally, the data shows that paired group and context and sound-exposed group have a lower relative EGR1 protein expression when compared to animals that were not subjected to any Several studies suggest the existence of multiple memory systems that interact in a competitive or comparative way. There are evidences that the processes of learning and memory depend on the integrity of the regions of the hippocampus, striatum and prefrontal cortex. It has been shown that these three structures are involved in fear conditioning, a task that evaluates emotional memory. During the training of fear conditioning task, a footshock can be paired with the environment (context foreground; CFC) or a cued stimulus such as a sound (in this case, the conditioning of the context is secondary, called contextual background; TFC). This memory can also be evaluated by techniques of molecular biology, studying genes involved in neural plasticity, such as the expression of immediate early genes (IEGs). Our hypothesis was to evaluate the expression of IEGs after an aversive memory task. In the present study, the hippocampus was inactivated with administration of AP-5, a glutamate antagonist, in order to verify the possible interaction between these brain structures by analyzing the IEGs c-fos, Egr1 and Arc in the hippocampus, prefrontal cortex and striatum after TFC training task. In the first part of the study, it was observed that the AP-5 impairs CFC, but not TFC. In the second part of the study, we evaluated gene expression (by real-time PCR) and protein expression (by Western blot) of IEGs 30 and 90 minutes after TFC training. When TFC was performed and the hippocampus was inactivated with AP-5, it was expected a lesser contextual participation, so the participation of the striatum in this type of conditioning could be better studied. However, our data suggests that administration of AP-5 in the hippocampus do not interfere with the expression of c-fos, Egr1 and Arc in striatum, hippocampus and prefrontal cortex, since groups of animals that received AP-5 have similar expression when compared to control groups that received saline. Furthermore, administration of AP-5 directly in the hippocampus increased gene expression of IEGs in this structure 30 minutes after TFC training. Finally, the data shows that paired group and context and sound-exposed group have a lower relative EGR1 protein expression when compared to animals that were not subjected to any / FAPESP: 2008/04305-2
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.unifesp.br:11600/41514 |
| Date | January 2013 |
| Creators | Antonio, Bruno de Brito [UNIFESP] |
| Contributors | Universidade Federal de São Paulo [UNIFESP], Oliveira, Maria Gabriela Menezes de [UNIFESP] |
| Publisher | Universidade Federal de São Paulo [UNIFESP] |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/doctoralThesis |
| Format | 148 p. |
| Source | reponame:Repositório Institucional da UNIFESP, instname:Universidade Federal de São Paulo, instacron:UNIFESP |
| Rights | info:eu-repo/semantics/openAccess |
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