New insights into the mechanism of imposex induction in the dogwhelk Nucella lapillus

• Tipo: Artigo em Revista Científica Internacional
• Data: 2005

Autores

Santos, MM (Autor) REIT; Castro, LFC (Autor) Outra; Vieira, MN (Autor) FCUP; Micael, J (Autor) Outra; Morabito, R (Autor) Outra; Massanisso, P (Autor) Outra; Reis Henriques, MA (Autor) ICBAS

Revista

A Revista está pendente de validação pelos Serviços Administrativos.

Título: COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY C-TOXICOLOGY & PHARMACOLOGY

Vol. 141

Páginas: 101-109

ISSN: 1532-0456

Indexação

ISI Web of Knowledge - 75 Citações

Scopus - 81 Citações

Classificação Científica

FOS: Ciências médicas e da saúde > Medicina clínica

Outras Informações

ID Authenticus: P-000-3GP

DOI: 10.1016/j.cca.2005.05.008

Abstract (EN): In an attempt to clarify the mechanism(s) of tributyltin-mediated imposex induction in females of the neogastropod Nucella lapillus, dogwhelks collected in an almost imposex free population were exposed to several treatments for a 3 month-period, and the effects on imposex induction and testosterone/estradiol levels were evaluated. As a positive control, tributyltin (50 ng TBT Sn/L) clearly induced imposex and led to a significant increase in the severity of the phenomenon. In contrast, although a selective P450 aromatase inhibitor (formestane at 0.3 mg/L) was capable of imposex induction, it failed to increase its severity. A vertebrate androgen receptor (AR) antagonist (cyproterone acetate at 1.25 mg/L) in combination with TBT completely blocked the imposex induction capacity of TBT. On the other hand, an estrogen receptor antagonist (tamoxifen at 0.3 mg/L) rendered no effect. The determination of steroid levels in female specimens revealed that TBT induces an elevation of free testosterone (but not the total amount, free + esterified), while the co-administration of the anti-androgen and TBT was able to rescue the increase of free testosterone levels. Despite a minor decrease in the amount of testosterone-fatty acid esters in the TBT group, significant differences in,esterified testosterone were not found among treatments. On the contrary, free estradiol levels were elevated in the TBT, anti-androgens and TBT plus anti-androgens groups. These results indicate that free estradiol biosynthesis in TBT-exposed females does not seem to be affected. Overall, our results demonstrate that a selective aromatase inhibitor can induce imposex in N. lapillus but not to a similar extent of TBT, which may suggest the involvement of other mechanism in imposex induction, besides aromatase inhibition. Additionally, the study points to the involvement of AR receptors in imposex induction.

Idioma: Inglês

Tipo (Avaliação Docente): Científica

Nº de páginas: 9