Estradiol and reproduction in the South American toad Rhinella arenarum (Amphibian, Anura)

Rhinella arenarum is a South American toad with wide geographic distribution. Testes of this toad produce high amount of androgens during the non reproductive season and shift steroid synthesis from androgens to 5α-pregnanedione during the breeding. In addition, plasma estradiol (E 2 ) in males of t...

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Detalles Bibliográficos
Publicado: 2019
Materias:
Estradiol
Gonadotropins
Spermatogenesis
Steroidogenesis
Testes
Toad
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00166480_v273_n_p20_Scaia
http://hdl.handle.net/20.500.12110/paper_00166480_v273_n_p20_Scaia
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_00166480_v273_n_p20_Scaia
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spelling paper:paper_00166480_v273_n_p20_Scaia2023-06-08T14:38:22Z Estradiol and reproduction in the South American toad Rhinella arenarum (Amphibian, Anura) Estradiol Gonadotropins Spermatogenesis Steroidogenesis Testes Toad Rhinella arenarum is a South American toad with wide geographic distribution. Testes of this toad produce high amount of androgens during the non reproductive season and shift steroid synthesis from androgens to 5α-pregnanedione during the breeding. In addition, plasma estradiol (E 2 ) in males of this species shows seasonal variations but, since testes of R. arenarum do not express aromatase, the source of plasma E 2 remained unknown for several years. However, the Bidder's organ (BO), a structure located at one pole of each testis, is proposed to be the main source of E 2 in male's toads since it expresses several steroidogenic enzymes and is able to produce E 2 from endogenous substrates throughout the year. In addition, there were significant correlations between plasma E 2 and total activity of BO aromatase, and between plasma E 2 and the amount of hormone produced by the BO in vitro. In the toad, apoptosis induced by in vitro treatment with E 2 was mostly detected in spermatocytes during the breeding and in spermatids during the post-reproductive season, suggesting that this steroid has an important role in controlling spermatogenesis. However, in vitro treatment with E 2 had no effect on proliferation. This evidence suggests that the mechanism of action of E 2 on amphibian spermatogenesis is complex and more studies are necessary to fully understand the role of estrogens regulating the balance between cellular proliferation and apoptosis. In addition, in R. arenarum in vitro studies suggested that E 2 has no effect on CypP450c17 protein levels or enzymatic activity, while it reduces 3β-hydroxysteroid dehydrogenase/isomerase (3β-HSD/I) activity during the post reproductive season. As well, E 2 regulates FSHβ mRNA expression all over the year suggesting a down regulation process carried out by this steroid. The effect on LHβ mRNA is dual, since during the reproductive season estradiol increases the expression of LHβ mRNA while in the non-reproductive season it has no effect. In conclusion, the effect of E 2 on gonadotropins and testicular function is complex, not clearly understood and probably varies depending on the species. The aim of the current article is to review evidence on reproductive endocrinology and on the role of estradiol regulating reproduction in amphibians, with emphasis on the South American species Rhinella arenarum. © 2018 Elsevier Inc. 2019 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00166480_v273_n_p20_Scaia http://hdl.handle.net/20.500.12110/paper_00166480_v273_n_p20_Scaia
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
topic Estradiol
Gonadotropins
Spermatogenesis
Steroidogenesis
Testes
Toad
spellingShingle Estradiol
Gonadotropins
Spermatogenesis
Steroidogenesis
Testes
Toad
Estradiol and reproduction in the South American toad Rhinella arenarum (Amphibian, Anura)
topic_facet Estradiol
Gonadotropins
Spermatogenesis
Steroidogenesis
Testes
Toad
description Rhinella arenarum is a South American toad with wide geographic distribution. Testes of this toad produce high amount of androgens during the non reproductive season and shift steroid synthesis from androgens to 5α-pregnanedione during the breeding. In addition, plasma estradiol (E 2 ) in males of this species shows seasonal variations but, since testes of R. arenarum do not express aromatase, the source of plasma E 2 remained unknown for several years. However, the Bidder's organ (BO), a structure located at one pole of each testis, is proposed to be the main source of E 2 in male's toads since it expresses several steroidogenic enzymes and is able to produce E 2 from endogenous substrates throughout the year. In addition, there were significant correlations between plasma E 2 and total activity of BO aromatase, and between plasma E 2 and the amount of hormone produced by the BO in vitro. In the toad, apoptosis induced by in vitro treatment with E 2 was mostly detected in spermatocytes during the breeding and in spermatids during the post-reproductive season, suggesting that this steroid has an important role in controlling spermatogenesis. However, in vitro treatment with E 2 had no effect on proliferation. This evidence suggests that the mechanism of action of E 2 on amphibian spermatogenesis is complex and more studies are necessary to fully understand the role of estrogens regulating the balance between cellular proliferation and apoptosis. In addition, in R. arenarum in vitro studies suggested that E 2 has no effect on CypP450c17 protein levels or enzymatic activity, while it reduces 3β-hydroxysteroid dehydrogenase/isomerase (3β-HSD/I) activity during the post reproductive season. As well, E 2 regulates FSHβ mRNA expression all over the year suggesting a down regulation process carried out by this steroid. The effect on LHβ mRNA is dual, since during the reproductive season estradiol increases the expression of LHβ mRNA while in the non-reproductive season it has no effect. In conclusion, the effect of E 2 on gonadotropins and testicular function is complex, not clearly understood and probably varies depending on the species. The aim of the current article is to review evidence on reproductive endocrinology and on the role of estradiol regulating reproduction in amphibians, with emphasis on the South American species Rhinella arenarum. © 2018 Elsevier Inc.
title Estradiol and reproduction in the South American toad Rhinella arenarum (Amphibian, Anura)
title_short Estradiol and reproduction in the South American toad Rhinella arenarum (Amphibian, Anura)
title_full Estradiol and reproduction in the South American toad Rhinella arenarum (Amphibian, Anura)
title_fullStr Estradiol and reproduction in the South American toad Rhinella arenarum (Amphibian, Anura)
title_full_unstemmed Estradiol and reproduction in the South American toad Rhinella arenarum (Amphibian, Anura)
title_sort estradiol and reproduction in the south american toad rhinella arenarum (amphibian, anura)
publishDate 2019
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00166480_v273_n_p20_Scaia
http://hdl.handle.net/20.500.12110/paper_00166480_v273_n_p20_Scaia
_version_ 1768542487992860672

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