Alterações comportamentais e fisiológicas causadas pela exposição a baixas doses de radiação ionizante durante o desenvolvimento intrauterino
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Data
2019-02-21
Autores
Giarola, Rodrigo Sanchez
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Universidade Estadual Paulista (Unesp)
Resumo
Os efeitos biológicos da radiação ionizante são causados pela deposição de energia no tecido. Efeitos de baixas doses de radiação ionizante induzem consequências de longo alcance, especialmente durante desenvolvimento intrauterino. Os riscos de exposição in utero permanecem controversos na literatura e nenhum efeito biológico é relatado em doses abaixo de 50 mGy. Modelos animais são frequentemente utilizados para investigação dos efeitos biológicos das radiações ionizantes pois permitem a manipulação de diversas configurações experimentais. Esse trabalho investigou o impacto da exposição intrauterina a baixa dose de radiação ionizante no desenvolvimento pós-natal de ratos. Ratas Wistar foram expostas a 15 mGy de raios X nos dias gestacionais 8 e 15, respectivamente o início e o fim da fase organogênese. Quatro animais machos foram selecionados de cada ninhada para o estudo. Nos recém-nascidos foram realizados o teste de abertura dos olhos e o teste de geotaxia negativa. Nas idades pós-natais de 30 e 70 dias, jovens e adultos, os animais foram testados no teste de campo aberto, no labirinto em cruz elevado e hole board. Avaliou-se o ganho de peso de todos os animais ao longo de todo experimento. Através dos resultados das avaliações identificou-se menor ganho de peso dos ratos expostos durante o desenvolvimento fetal quando adultos. Foram encontradas fortes evidências de alterações comportamentais e prejuízos no sistema nervoso central, também, observou-se comprometimento da coordenação motora em ratos expostos durante o desenvolvimento intrauterino. O presente estudo constatou que um valor de exposição considerado seguro produz efeitos deletérios na prole exposta durante o desenvolvimento intrauterino.
Low-dose ionizing radiation may induce far-reaching consequences in human, especially regarding intrauterine development. Many studies have documented that the risks of in utero irradiation remain controversial and no effect is reported at doses below 50 mGy. Animal models are often used to clarify the non-fully understood impact of intrauterine irradiation and allow the manipulation of several experimental setups, making possible the analysis of a wide range of end points. We investigated the impact of in utero low-dose X-ray irradiation on postnatal development in rat offspring through a set of well-established behavioral parameters and weight gain. We exposed pregnant Wistar to 15 mGy of X-rays, which is a low-dose value into diagnostic range that can be achieved in a single radiological exam, on gestational days 8 and 15 and control. Four male animals were select from each litter. At infant age, eye-opening test and negative geotaxis tests were performed. Animals were tested at postnatal ages 30 and 70 days in open field, elevated plus-maze, and hole board tests. We evaluated the weight gain of all animals throughout the experiment. Our results present difference between irradiated and non-irradiated: lower weight gain when adults, impairments in the central nervous system since infant phase, behavioral changes persisting later into life and impairment of motor coordination in irradiated animals. The present study found that even low-doses exposure, considered safe, during pregnancy were able to induce behavioral impairment and lower weight gain in rat’s offspring.
Low-dose ionizing radiation may induce far-reaching consequences in human, especially regarding intrauterine development. Many studies have documented that the risks of in utero irradiation remain controversial and no effect is reported at doses below 50 mGy. Animal models are often used to clarify the non-fully understood impact of intrauterine irradiation and allow the manipulation of several experimental setups, making possible the analysis of a wide range of end points. We investigated the impact of in utero low-dose X-ray irradiation on postnatal development in rat offspring through a set of well-established behavioral parameters and weight gain. We exposed pregnant Wistar to 15 mGy of X-rays, which is a low-dose value into diagnostic range that can be achieved in a single radiological exam, on gestational days 8 and 15 and control. Four male animals were select from each litter. At infant age, eye-opening test and negative geotaxis tests were performed. Animals were tested at postnatal ages 30 and 70 days in open field, elevated plus-maze, and hole board tests. We evaluated the weight gain of all animals throughout the experiment. Our results present difference between irradiated and non-irradiated: lower weight gain when adults, impairments in the central nervous system since infant phase, behavioral changes persisting later into life and impairment of motor coordination in irradiated animals. The present study found that even low-doses exposure, considered safe, during pregnancy were able to induce behavioral impairment and lower weight gain in rat’s offspring.
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Proteção Radiológica, Radiologia, Testes Comportamentais, Programação Fetal