O efeito do enriquecimento ambiental na morfologia do hipocampo e na densidade neuronal do córtex perirrinal e na região da amígdala na prole de ratas com hipotireoidismo clínico gestacional
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Tipo
TCC
Data de publicação
2023-06
Periódico
Citações (Scopus)
Autores
Brás, Tayna Sabrina
Orientador
Ribeiro, Miriam Oliveira
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Resumo
O primeiro trimestre de gestação é considerado um período crítico no desenvolvimento do sistema nervoso central do feto, que é dependente do hormônio tireoidiano. Considerando que a tireoide fetal amadurece e se torna biologicamente ativa na 14ª semana de gestação, o hormônio tireoidiano materno é fundamental para que esse processo transcorra adequadamente. Assim, falhas na disponibilidade de hormônio tireoidiano materno nos estágios iniciais de desenvolvimento podem acarretar impactos cognitivos e comportamentais na prole. Estudos mostram que crianças de até 9 anos de idade, cujo as mães apresentaram hipotireoidismo clínico no 1º trimestre gestacional, revelaram déficits de QI em comparação a crianças de mães eutireoideas. O desenvolvimento de estratégias que visem corrigir esses possíveis déficits é essencial para garantir o desenvolvimento e qualidade de vida desses indivíduos. O enriquecimento ambiental é uma estratégia que compreende estímulos físicos, sensoriais, sociais, cognitivos e alimentares que melhora os comportamentos considerados normais e inibe o aparecimento de comportamentos anormais nos animais. De fato, o enriquecimento ambiental demonstrou, em estudos anteriores, melhoras significativas na restauração da memória de curto prazo e a ansiedade, e também a melhora dos comportamentos depressivos de filhotes de ratas com hipotireoidismo gestacional moderado. Assim, o objetivo do presente estudo foi avaliar se o enriquecimento ambiental modificou a densidade neuronal e a morfologia das áreas do hipocampo, córtex perirrinal, amígdala e específicamente a amígdala basolateral e quais os mecanismos envolvidos na melhora da cognição induzidas pelo enriquecimento ambiental em filhotes de fêmeas com hipotireoidismo moderado. Utilizamos um protocolo de enriquecimento ambiental de 8 semanas padronizado pelo próprio grupo de pesquisa. Após isso, fatiamos os cérebros dos ratos para posterior coloração e análise das regiões escolhidas. Nosso estudo mostrou que não há diferença estatisticamente significativa na análise das áreas do hipocampo (CA1, CA2, CA3) e das estruturas do córtex perirrinal, amígdala e amígdala basolateral entre os grupos estudados. No entanto, observou-se um aumento significativo na espessura do giro denteado (GD) nos animais do grupo HCEA em comparação com o grupo HC n-EA.
The first trimester of gestation is considered a critical period in the development of the fetal central nervous system, which is dependent on thyroid hormone. Considering that the fetal thyroid matures and becomes biologically active by the 14th week of gestation, maternal thyroid hormone is critical for this process to take place properly. Thus, failures in the availability of maternal thyroid hormone in the early stages of development can lead to cognitive and behavioral impacts on the offspring. Studies show that children up to 9 years of age, whose mothers had clinical hypothyroidism in the 1st trimester of gestation, showed IQ deficits compared to children from euthyroid mothers. The development of strategies that aim to correct these possible deficits is essential to ensure the development and quality of life of these individuals. Environmental enrichment is a strategy that comprises physical, sensory, social, cognitive, and food stimuli that improves behaviors considered normal and inhibits the appearance of abnormal behaviors in animals. Indeed, environmental enrichment has demonstrated, in previous studies, significant improvements in restoring short-term memory and anxiety, and also the improvement of depressive behaviors in pups of rats with moderate gestational hypothyroidism. Thus, the aim of the present study was to evaluate whether environmental enrichment modified the neuronal density and morphology of the areas of the hippocampus, perirhinal cortex, amygdala and specifically the basolateral amygdala, and what mechanisms are involved in the improvement of cognition induced by environmental enrichment in female pups with moderate hypothyroidism. We used an 8-week environmental enrichment protocol standardized by our own research group. After this, we sliced the brains of the rats for subsequent staining and analysis of the chosen regions. Our study showed no statistically significant difference in the analysis of hippocampal areas (CA1, CA2, CA3) and structures of the perirhinal cortex, amygdala and basolateral amygdala between the groups studied. However, a significant increase in the thickness of the dentate gyrus (GD) was observed in the animals of the HC-EA group compared to the HC n-EA group.
The first trimester of gestation is considered a critical period in the development of the fetal central nervous system, which is dependent on thyroid hormone. Considering that the fetal thyroid matures and becomes biologically active by the 14th week of gestation, maternal thyroid hormone is critical for this process to take place properly. Thus, failures in the availability of maternal thyroid hormone in the early stages of development can lead to cognitive and behavioral impacts on the offspring. Studies show that children up to 9 years of age, whose mothers had clinical hypothyroidism in the 1st trimester of gestation, showed IQ deficits compared to children from euthyroid mothers. The development of strategies that aim to correct these possible deficits is essential to ensure the development and quality of life of these individuals. Environmental enrichment is a strategy that comprises physical, sensory, social, cognitive, and food stimuli that improves behaviors considered normal and inhibits the appearance of abnormal behaviors in animals. Indeed, environmental enrichment has demonstrated, in previous studies, significant improvements in restoring short-term memory and anxiety, and also the improvement of depressive behaviors in pups of rats with moderate gestational hypothyroidism. Thus, the aim of the present study was to evaluate whether environmental enrichment modified the neuronal density and morphology of the areas of the hippocampus, perirhinal cortex, amygdala and specifically the basolateral amygdala, and what mechanisms are involved in the improvement of cognition induced by environmental enrichment in female pups with moderate hypothyroidism. We used an 8-week environmental enrichment protocol standardized by our own research group. After this, we sliced the brains of the rats for subsequent staining and analysis of the chosen regions. Our study showed no statistically significant difference in the analysis of hippocampal areas (CA1, CA2, CA3) and structures of the perirhinal cortex, amygdala and basolateral amygdala between the groups studied. However, a significant increase in the thickness of the dentate gyrus (GD) was observed in the animals of the HC-EA group compared to the HC n-EA group.
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Palavras-chave
gestação , enriquecimento ambiental , hipotireoidismo , pregnancy , environmental enrichment , hypothyroidism