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Steroid metabolism by ovarian follicles of the sea bass Dicentrarchus labrax

Título
Steroid metabolism by ovarian follicles of the sea bass Dicentrarchus labrax
Tipo
Artigo em Revista Científica Internacional
Ano
2000
Autores
Revista
A Revista está pendente de validação pelos Serviços Administrativos.
Vol. 125
Páginas: 85-91
ISSN: 1532-0456
Indexação
Classificação Científica
FOS: Ciências exactas e naturais > Ciências biológicas
Outras Informações
ID Authenticus: P-001-1AA
Abstract (EN): Ovarian samples from fear sea bass, Dicentrarchus labrax, were collected for the in vitro incubations during the spawning period. Follicles with fully developed vitellogenic oocytes showing central germinal Vesicle (stage I follicles) and follicles with oocytes showing initial germinal vesicle migration (stage II follicles) were treated with either (1) 20 mu g sea bass hypophysis plus 50 ng 17-hpdroxyprogesterone (17-P), (2) 20 mu g hypophysis alone, (3) 50 ng 17-P alone and (4) media alone. Structure-activity experiments used stage II follicles treated with several dosages (0.1, 1.0 and 10.0 ng/ml) of either 17-P, 17,20 beta-P, or 17,20 beta,21-P. Free and conjugated (sulfates and glucuronides) levels of the established teleost oocyte maturation inducing steroids (MIS), i.e. 17,20 beta-dihydroxy-4-pregnen-3-one (17,20 beta-P) and 17,20 beta,21-trihydroxy-4-pregnen-3-one (17,20 beta,21-P) were measured in the incubation media by high performance liquid chromatography. Our results show that the synthesis of free and conjugated 17,20 beta-P is constant (0.1-0.2 ng/ml) in all incubates. In contrast, the synthesis of free and conjugated 17,20 beta,21-P is higher in incubates containing stage II follicles (up to 5 ng/ml) than in those having stage I follicles (up to 3 ng/ml; P < 0.01). Structure-activity data reveal that 17-P is not effective at inducing in vitro germinal vesicle breakdown whereas both 17,20 beta-P and 17,20 beta,21-P are equally potent and highly effective. These results demonstrate that 17,20 beta-P and 17,20 beta,21-P are synthesized in vitro by follicles of sea bass and that sulfation is the main route for the metabolism of the C-21-steroids in riper follicles. The highest levels of 17,20 beta,21-P, found in incubates containing stage II follicles, points at 17,20 beta,21-P, rather than 17,20 beta-P, as the most probable MIS in sea bass, nonetheless, this hypothesis requires further confirmation. (C) 2000 Elsevier Science Inc. All rights reserved.
Idioma: Inglês
Tipo (Avaliação Docente): Científica
Nº de páginas: 7
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