In Vivo Anti-estrogenic Effects of Menadione on Hepatic Estrogen-responsive Gene Expression in Male Medaka (Oryzias latipes)

• Published in: Journal of Health Science 2008, Vol.54(5), pp.596-601
• Main Authors: Yamaguchi, Akemi, Kohra, Shinya, Ishibashi, Hiroshi, Arizono, Koji, Tominaga, Nobuaki
• Format: Article
• Language: English
• Subjects: anti-estrogenic; in vivo; menadione; Oryzias latipes
• ISSN: 1344-9702; 1347-5207
• DOI: 10.1248/jhs.54.596

Menadione, a synthetic vitamin K3, exhibits anti-estrogenic activity on in vitro assay. However, the in vivo anti-estrogenic effects of menadione have not been determined, while correlations between biological effects and structural changes are unclear. Thus, we investigated the in vivo anti-estrogenic activity of menadione under fluorescent light and dark conditions. Suppression of the hepatic estrogen response genes vitellogenin1 (VTG1), VTG2 and estrogen receptor-α (ER-α) was used as an index of anti-estrogenic activity. Male medaka (Oryzias latipes) were treated with nominal concentrations of menadione in the presence or absence of 17β-estradiol (E2), and hepatic VTG1, VTG2 and ER-α mRNA levels were determined by quantitative real-time PCR. In the presence of E2 under dark conditions, expression of hepatic VTG2 and ER-α genes was suppressed by menadione treatment. On the other hand, menadione activity was lost under fluorescent light conditions. These results suggest that menadione has anti-estrogenic activity in vivo, and that this activity is diminished under fluorescent light, probably due to a structural change in menadione.