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Previous issue date: 2012-12-10 / Financiadora de Estudos e Projetos / Several studies have shown that benzodiazepines (BDZ) in periaqueductal gray (PAG) can produce anxiolytic-like effects in different animal models of anxiety. In addition, BDZ drugs also impair learning and memory performance in rodents. Despite the known role of PAG in modulated defensive behaviors in animal models, little is known about its role in modulated of emotional memory. In this sense, the objective of this study was to investigate the effects of midazolam, injected into the PAG, on the acquisition, consolidation and retrieval of aversive memory. For this, we used male mice of the Swiss-Albino weighing between 25-30g (n=7-11). After stereotactic surgery with implantation of a cannula in the PAG, the animals on the test day were divided into three experiments for later exposed to the test "step-down" (SD), as follows: Experiment 1, intra-PAG with saline and midazolam (MDZ) at doses of 3.0 and 30 nmol/0.1μl, in condition of pre-training to evaluate the acquisition of aversive memory; Experiment 2 was like Experiment 1, except for the condition of the injection pretest to evaluate the retrieval of aversive memory; Experiment 3 was like Experiment 1, except for the condition of injection post training to evaluate the consolidation of aversive memory. The animals were trained in the inhibitory avoidance task that was to distributed the animals into two groups: N/Sh - without exposure to shock, W/Sh - with exposed to shock (0.5 mA) for 10 seconds, to record the latency of descent (L1). Twenty-four hours later, each animal was exposed again on SD to record latency (L2), but without shock. The results were evaluated by analysis of variance (ANOVA) of three factors (Factor 1: condition; Factor 2: pre-treatment Factor 3: treatment) for L1 and L2. The results showed that there was an increase of L2 after exposure of mice to SD without shock, confirming that the aversive stimulus (shock) was strong enough to promote facilitation of aversive memory. The two doses (3.0 and 30 nmol) of MDZ intra-PAG decreased the risk assessment of mice, characterized by the fast descent of the platform in L1. This result suggests that GABAbenzodiazepine agonist impaired the acquisition, consolidation and retrieval of aversive memory in mice. Taken together, these results suggest that GABAA receptors within PAG seem to modulate the response related to aversive memory induced by shock. / Varios estudos tem demonstrado que os benzodiazepinicos (BDZ), administrados na substancia cinzenta periaquedutal (SCP), podem produzir efeito ansiolitico em diferentes modelos animais de ansiedade e tambem prejudicar a aprendizagem e a memoria em roedores. Apesar do ja conhecido papel da SCP em modular comportamentos defensivos em modelos animais, pouco se sabe sobre o seu papel na modulacao da memoria emocional. Neste sentido, o objetivo desde estudo foi investigar os efeitos do midazolam, intra-SCP, sobre a aquisicao, consolidacao e evocacao da memoria aversiva. Para isto, utilizamos camundongos machos da linhagem Suico-Albino, pesando entre 25-30g (n=7-11/grupo). Os animais apos cirurgia estereotaxica com implantacao de canula na SCP, no dia do teste foram distribuidos em tres Experimentos para posteriormente serem expostos ao teste de step-down (SD), a saber: Experimento 1, injecao intra-SCP com salina e midazolam (MDZ) nas doses de 3,0 e 30 nmol/0,1μl, na condicao de pre-treino ao SD para avaliar a aquisicao da memoria aversiva; Experimento 2, conforme Experimento 1, exceto pela condicao de injecao pre-teste ao SD para avaliar a evocacao da memoria aversiva; Experimento 3, conforme Experimento 1, exceto pela condicao de injecao pos-treino ao SD para avaliar a consolidacao da memoria aversiva. Os animais foram treinados na tarefa de esquiva inibitoria que consistiu em distribuir os animais em dois grupos: S/Ch - sem exposicao ao choque; C/Ch com exposicao ao choque (0,5mA) por 10s, para registro da latencia de descida (L1). Vinte e quatro horas apos, cada animal foi exposto novamente ao SD para registro da latencia (L2), mas sem o choque. Os resultados foram avaliados pela analise de variancia (ANOVA) de tres fatores (Fator 1: condicao; Fator 2: pre-tratamento; Fator 3: tratamento), durante L1 e L2. Os resultados mostraram que ocorreu aumento de L2, apos a exposicao de camundongos ao SD sem apresentacao de choque, confirmando que o estimulo aversivo (choque) foi forte o suficiente para promover facilitacao da memoria aversiva. As duas doses (3,0 e 30 nmol) de MDZ intra-SCP diminuiram a avaliacao de risco dos camundongos, caracterizada pela rapida descida da plataforma em L1. Este resultado sugere que este agonista GABABenzodiazepinico, prejudicou a aquisicao, evocacao e consolidacao da memoria aversiva em camundongos. Em conjunto, esses resultados sugerem que os receptores GABAA localizados na SCP participam da modulacao das respostas relacionadas a memoria aversiva induzida pelo choque.
| Identifer | oai:union.ndltd.org:IBICT/oai:repositorio.ufscar.br:ufscar/6037 |
| Date | 10 December 2012 |
| Creators | Pereira, Barbara Caetano |
| Contributors | Souza, Azair Liane Matos do Canto de |
| Publisher | Universidade Federal de São Carlos, Programa de Pós-graduação em Psicologia, UFSCar, BR |
| Source Sets | IBICT Brazilian ETDs |
| Language | Portuguese |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis |
| Format | application/pdf |
| Source | reponame:Repositório Institucional da UFSCAR, instname:Universidade Federal de São Carlos, instacron:UFSCAR |
| Rights | info:eu-repo/semantics/openAccess |
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