Exposição ao benzo(a)pireno em ratos machos do período juvenil até a peripuberdade: repercussões na vida adulta em parâmetros reprodutivos e impactos na prole
Carregando...
Data
2019-02-28
Autores
Jorge, Bárbara Campos [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Entre as substâncias com potencial de desregulação endócrina, destaca-se o Benzo(a)pireno (BaP), um poluente orgânico persistente e amplamente difundido no ambiente. É gerado pela combustão incompleta de compostos orgânicos e está presente na fumaça de cigarro, na exaustão de automóveis, em alimentos e água contaminados. Estudos demonstram que o BaP se acumula em órgãos vitais e reprodutores, incluindo o testículo, e pode interferir no processo de esteroidogênese, através da interação com a proteína StAR. Sabe-se que substâncias que atuam como desreguladores endócrinos (DEs) podem gerar prejuízos não somente no indivíduo exposto, mas também nas gerações subsequentes, via células germinativas. A exposição aos DEs torna-se mais relevante em períodos hormônio-dependentes, como a gestação, a infância e a peripuberdade, denominados de janelas críticas do desenvolvimento. Assim, torna-se fundamental a investigação da exposição ao BaP durante uma janela crítica do desenvolvimento (juvenil e peripuberdade) e avaliar quais são as repercussões disto na vida reprodutiva, bem como os possíveis impactos no desenvolvimento e reprodução da prole, via paterna. Para tal, 40 ratos machos Wistar no período juvenil (23 dias de idade) foram distribuídos em quatro grupos experimentais, sendo um controle (óleo de milho + DMSO); e três grupos que receberam diferentes doses de BaP: 0,1, 1,0 ou 10 μg/kg/dia. A exposição ao poluente ocorreu durante 31 dias consecutivos, do dia pós-natal (DPN) 23 ao 53, via oral (gavage). Durante o tratamento, foram avaliados sinais clínicos de toxicidade e a instalação da puberdade, e na vida adulta (DPN 90) foram realizados o comportamento sexual, teste de fertilidade e acasalamento natural com fêmeas não tratadas (gerando a prole de interesse). Posteriormente, os órgãos vitais, reprodutores e sangue foram coletados para as seguintes análises: parâmetros espermáticos (morfologia, motilidade e contagem), hematológicos, histológicos do testículo (dinâmica espermatogênica, contagem e volume das células de Leydig) e quantificação da proteína StAR. Na prole feminina, foram avaliados: parâmetros inicias do desenvolvimento sexual, instalação da puberdade, ciclo estral, teste de fertilidade e histologia do ovário. Na prole masculina, foram avaliados: parâmetros iniciais do desenvolvimento sexual, descida testicular, separação prepucial e parâmetros espermáticos na vida adulta. A exposição ao BaP causou prejuízos nos animais expostos (geração parental-F0), comprometendo parâmetros espermáticos, hematológicos e histológicos do testículo, principalmente no grupo de menor dose. Além disso, o BaP demonstrou ter um efeito multigeracional. A prole feminina e masculina (F1) apresentaram alterações nos parâmetros do desenvolvimento sexual e na fertilidade na vida adulta (fêmeas), indicando que a exposição ao BaP acarretou em uma programação do desenvolvimento de origem paterna para alterações reprodutivas, em ambos os sexos. O padrão de resposta observada nesse estudo foi uma curva dose-resposta não-monotônica, característica de substâncias que se comportam como DEs. Assim, o benzo(a)pireno, neste modelo experimental, é capaz de causar impactos negativos na reprodução na vida adulta dos animais expostos durante o período juvenil até a peripuberdade, bem como de causar efeitos multigeracionais, comprometendo o desenvolvimento reprodutivo de seus descendentes. Aprovado pelo comitê de ética 958/2017 (CEUA/IBB).
Among substances with potential for endocrine disruptor, benzo(a)pyrene (BaP), a persistent organic pollutant widely distributed in the environment, stands out. It is generated by the incomplete combustion of organic compounds and is present in cigarette smoke, exhaust from cars, contaminated food and water. Studies have shown that BaP accumulates in vital and reproductive organs, including the testis; and may interfere with the steroidogenesis process through interaction with the StAR protein. It is known that substances that act as endocrine-disrupting chemicals (EDCs) can generate damages not only in the exposed individual, but also in subsequent generations by germ cells. Exposure to EDCs becomes more relevant in hormone-dependent periods, such as gestation, childhood and peripuberty, called critical windows of development. Thus, it is essential to investigate exposure to BaP during the critical development window (juvenile and peripuberty) and to investigate the repercussions of this on reproductive life and the possible impacts on the development and reproduction of the offspring, paternal way. For this, 40 male Wistar rats were used in the juvenile period (23 days of age) and distributed into four experimental groups, one control (corn oil + DMSO); and three groups receiving different doses of BaP: 0.1, 1.0 or 10 μg/kg/ day. The exposure to pollutant occurred during 31 consecutive days, from the postnatal day (PND) 23 to 53, via oral (gavage). During the treatment, clinical signs of toxicity and preputial separation were evaluated, and sexual behavior, fertility testing and natural mating with untreated females (generating offspring of interest) were performed in adulthood. Subsequently, vital organs, breeding and blood were collected for the following analyzes: sperm parameters (morphology, motility and counting), hematological, histological of the testis (spermatogenic dynamics, counting and volume of Leydig cells) and StAR protein quantification. In the female offspring, the following parameters were evaluated: initial reproductive parameters of the development, puberty, estrous cycle, fertility test and ovary histology. In the male offspring, the following were evaluated: initial reproductive parameters of development, testicular descent, preputial separation and sperm parameters in adult life. From the parental generation (F0), the spermatic, hematological and histological parameters of the testis were altered, mainly in the lower dose group, showing losses in sperm quality of these animals. In addition, BaP has been shown to have a multigenerational effect. Female and male offspring (F1) presented changes in the parameters of sexual development and fertility in adult life (females), indicating that the exposure to BaP resulted in a developmental programming from paternal origins to reproductive alterations in both sexes. The response pattern observed in this study was a non-monotonic dose-response curve, characteristic of substances that behave as EDCs. Thus, benzo(a)pyrene in this experimental model can cause negative impacts on reproduction in adult life of exposed animals during the juvenile period until peripuberty, as well as causing multigenerational effects, compromising the reproductive development of their offspring. Approved by ethics committee, nº 958/2017 (CEUA/IBB).
Among substances with potential for endocrine disruptor, benzo(a)pyrene (BaP), a persistent organic pollutant widely distributed in the environment, stands out. It is generated by the incomplete combustion of organic compounds and is present in cigarette smoke, exhaust from cars, contaminated food and water. Studies have shown that BaP accumulates in vital and reproductive organs, including the testis; and may interfere with the steroidogenesis process through interaction with the StAR protein. It is known that substances that act as endocrine-disrupting chemicals (EDCs) can generate damages not only in the exposed individual, but also in subsequent generations by germ cells. Exposure to EDCs becomes more relevant in hormone-dependent periods, such as gestation, childhood and peripuberty, called critical windows of development. Thus, it is essential to investigate exposure to BaP during the critical development window (juvenile and peripuberty) and to investigate the repercussions of this on reproductive life and the possible impacts on the development and reproduction of the offspring, paternal way. For this, 40 male Wistar rats were used in the juvenile period (23 days of age) and distributed into four experimental groups, one control (corn oil + DMSO); and three groups receiving different doses of BaP: 0.1, 1.0 or 10 μg/kg/ day. The exposure to pollutant occurred during 31 consecutive days, from the postnatal day (PND) 23 to 53, via oral (gavage). During the treatment, clinical signs of toxicity and preputial separation were evaluated, and sexual behavior, fertility testing and natural mating with untreated females (generating offspring of interest) were performed in adulthood. Subsequently, vital organs, breeding and blood were collected for the following analyzes: sperm parameters (morphology, motility and counting), hematological, histological of the testis (spermatogenic dynamics, counting and volume of Leydig cells) and StAR protein quantification. In the female offspring, the following parameters were evaluated: initial reproductive parameters of the development, puberty, estrous cycle, fertility test and ovary histology. In the male offspring, the following were evaluated: initial reproductive parameters of development, testicular descent, preputial separation and sperm parameters in adult life. From the parental generation (F0), the spermatic, hematological and histological parameters of the testis were altered, mainly in the lower dose group, showing losses in sperm quality of these animals. In addition, BaP has been shown to have a multigenerational effect. Female and male offspring (F1) presented changes in the parameters of sexual development and fertility in adult life (females), indicating that the exposure to BaP resulted in a developmental programming from paternal origins to reproductive alterations in both sexes. The response pattern observed in this study was a non-monotonic dose-response curve, characteristic of substances that behave as EDCs. Thus, benzo(a)pyrene in this experimental model can cause negative impacts on reproduction in adult life of exposed animals during the juvenile period until peripuberty, as well as causing multigenerational effects, compromising the reproductive development of their offspring. Approved by ethics committee, nº 958/2017 (CEUA/IBB).
Descrição
Palavras-chave
Peripuberdade, Desreguladores endócrinos, Benzo(a)pireno, Fertilidade, Programação paterna, peripuberty, endocrine disruptor, benzo(a)pyrene, fertility, paternal programming