US EPA

2727510 

Journal Article 

Expression of TGFbeta and CRABP proteins in embryos exposed in vitro to a triazole fungicide 

Menegola, E; Di Renzo, F; Broccia, ML; Giavini, E 

2007 

1 

Reproductive Toxicology
ISSN: 0890-6238
EISSN: 1873-1708 

DART/TER/7000781 

24 

1 

English 

Azole fungicides are teratogenic both in vitro and in vivo, and their effects have been related to the abnormal formation of the branchial ectomesenchyme. The postulated pathogenic pathway indicates the inhibition of CYP 26 enzyme, the consequent increase of endogenous retinoic acid (RA) concentrations and the abnormal expression of morphogenetic molecules controlled by RA as crucial in embryos. To verify this hypothesis, considering that abnormal TGFbetas expression has been described after exposure to exogenous RA, these proteins have been selected as indicative. Moreover, the expression of CRABP (Cellular Retinoic Acid Binding Protein) has been evaluated to verify if this protein resulted increased after azole exposure. 9.5-day-old rat embryos were exposed in vitro for 24 h to a teratogenic dose level of triadimefon (FON). The protein expression of TGFbetas and CRABP was determined by quantitative western blotting after 24, 28, 40, 48 h of culture. Immunohistochemical staining was also performed. InFONand controlsTGFbetas were expressed at 24 and 28 h, but the quantity in FON samples was half than controls. CRABP expression resulted significantly increased in FON samples after 24 h of culture. The histological distribution of the studied proteins showed in control a partial co-expression at the level of the ectomesenchyme, the heart and vitelline sac. FON samples were characterized by a weaker TGFbeta signal at the level of heart and vitelline sac and by the absence of signal at the level of ectomesenchyme. The obtained results support the previously postulated azole-related pathogenic pathway.