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Endocrine and molecular control involved on zebrafish (Danio rerio) spermatogenesis: effects of corticosteroids and thyroid hormones

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Author(s):
Aldo Tovo Neto
Total Authors: 1
Document type: Doctoral Thesis
Press: Jaboticabal. 2018-08-03.
Institution: Universidade Estadual Paulista (Unesp). Faculdade de Ciências Agrárias e Veterinárias. Jaboticabal
Defense date:
Advisor: Rafael Henrique Nóbrega; Emanuel Ricardo Monteiro Martinez
Abstract

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. (AU)

FAPESP's process: 14/16280-5 - Molecular and endocrine control involved on gonadal differentiation of zebrafish (Danio rerio)
Grantee:Aldo Tovo Neto
Support type: Scholarships in Brazil - Doctorate