Controle endócrino e molecular envolvidos na espermatogênese de zebrafish (Danio rerio): efeitos dos hormônios corticoides e tireoidianos
Carregando...
Data
2018-06-12
Autores
Tovo Neto, Aldo
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Diversas pesquisas deixam claro que os hormônios do metabolismo como o cortisol e hormônios tireoidianos (HTs, T3 e T4) podem influenciar a reprodução de peixes diretamente afetando hormônios do eixo hipotalâmico-hipofisário-gonadal, ou indiretamente por diferentes mecanismos. Embora os efeitos do cortisol na reprodução tenham sido estudados extensivamente, os efeitos diretos à nível gonadal receberam menos atenção nesse processo. Em relação aos HTs, estudos mostram uma correlação positiva entre HTs e o status reprodutivo, onde os HTs são frequentemente associados com o desenvolvimento testicular, crescimento e maturação. O objetivo desta tese foi estudar os efeitos do cortisol e HTs na espermatogênese de zebrafish utilizando cultura de órgãos ex vivo. Foram avaliados a proliferação de células germinativas, quantificação de cistos germinativos, liberação de andrógenos (ELISA) e expressão de genes testiculares. O cortisol tem um efeito positivo na espermatogênese estimulando a diferenciação de células germinativas e aumentando a quantidade de espermatozoides no lúmen, de forma independente de andrógeno. O T3 afetou a expressão de genes expressos em células germinativas, enquanto o T4 não alterou a expressão destes genes. Além disso, os estudos in vivo mostraram que o metimazol aumentou a área ocupada pelas espermatogônias do tipo A e tipo B, enquanto que a área do lúmen e a quantidade de espermatozoides reduziram significativamente, sugerindo que o hipotireoidismo induzido prejudica a meiose, além de modular a expressão de genes nas células de Sertoli e Leydig.
It has been increasingly clear that metabolic hormones such as cortisol and thyroid hormones (THs, T3 and T4) can also influence fish reproduction either directly by affecting hormones of the hipotalamic-pituitary-gonadal axis or indirectly by different mechanisms. Although the effects of cortisol in reproduction were extensively studied, directs effects at gonadal level has received less attention in this process. Regarding THs, it has been shown a positive correlation between THs and fish reproductive status, where THs are frequently associated with testicular development, growth and maturation. The aim of this thesis was to study the effects of cortisol and THs on zebrafish spermatogenesis using an ex vivo organs culture. We evaluated germ cell proliferation activity, quantification of germ cysts, androgen release by ELISA and the mRNA expression of testicular genes. Cortisol has a positive role in zebrafish spermatogenesis by stimulating germ cells differentiation and increase of free spermatozoa in the lumen, in an androgen independent manner. T3 affected germ cells related genes, while T4 did not alter these evaluated genes. Moreover, in vivo studies showed that methimazole increased the area occupied by the undifferentiated type A spermatogonia and type B spermatogonia, while spermatozoa and the lumen area were reduced significantly, which suggests that hypothyroidism-induced impairs meiosis and modulates the mRNA expression of Sertoli and Leydig cells genes.
It has been increasingly clear that metabolic hormones such as cortisol and thyroid hormones (THs, T3 and T4) can also influence fish reproduction either directly by affecting hormones of the hipotalamic-pituitary-gonadal axis or indirectly by different mechanisms. Although the effects of cortisol in reproduction were extensively studied, directs effects at gonadal level has received less attention in this process. Regarding THs, it has been shown a positive correlation between THs and fish reproductive status, where THs are frequently associated with testicular development, growth and maturation. The aim of this thesis was to study the effects of cortisol and THs on zebrafish spermatogenesis using an ex vivo organs culture. We evaluated germ cell proliferation activity, quantification of germ cysts, androgen release by ELISA and the mRNA expression of testicular genes. Cortisol has a positive role in zebrafish spermatogenesis by stimulating germ cells differentiation and increase of free spermatozoa in the lumen, in an androgen independent manner. T3 affected germ cells related genes, while T4 did not alter these evaluated genes. Moreover, in vivo studies showed that methimazole increased the area occupied by the undifferentiated type A spermatogonia and type B spermatogonia, while spermatozoa and the lumen area were reduced significantly, which suggests that hypothyroidism-induced impairs meiosis and modulates the mRNA expression of Sertoli and Leydig cells genes.
Descrição
Palavras-chave
Zebrafish, Espermatogênese, Expressão gênica, Fish, Hipotireoidismo