Effect of ethinylestradiol on the reproduction and induction of vitellogenin and testis-ova in medaka (Oryzias latipes).
Mature medaka (Oryzias latipes) were exposed to ethinylestradiol (EE2) at measured concentrations of 32.6, 63.9, 116, 261, and 488 ng/L for 21 d under flow-through conditions. Effects on reproductive success of the fish as well as on gonadal condition and vitellogenin (VTG) induction were assessed. A significant decrease in fecundity was observed only at the highest EE2 concentration, whereas hepatic VTG concentration in males was increased at concentrations of 63.9 ng/L and greater. In addition, an intersex condition (testis-ova) of the gonad was observed in male medaka exposed to EE2 concentrations of > or = 63.9 ng/L. Overall, these results indicate that the lowest-observed-effect concentrations of EE2 based on reproduction versus induction of both VTG and testis-ova in the medaka were 488 and 63.9 ng/L, respectively. Thus, the physiological and histological measurements were approximately eightfold more responsive to the EE2 exposure than were overt reproductive effects. This suggests that the elevated VTG levels and testis-ova may not be definitely responsible for reproductive impairment of the fish.
Seki
Masanori
M
Chemicals Evaluation and Research Institute, Japan, Kurume-shi, Fukuoka. seki-masanori@ceri.jp
Yokota
Hirofumi
H
Matsubara
Haruki
H
Tsuruda
Yukinari
Y
Maeda
Masanobu
M
Tadokoro
Hiroshi
H
Kobayashi
Kunio
K
D000818:Animals; D004305:Dose-Response Relationship, Drug; D045166:Estradiol Congeners / Q000009:adverse effects*; D004997:Ethinyl Estradiol / Q000009:adverse effects*; D005260:Female; D005298:Fertility / Q000187:drug effects*; D008297:Male; D009990:Oryzias / Q000502:physiology*; D010063:Ovum / Q000187:drug effects / Q000502:physiology; D013737:Testis / Q000187:drug effects / Q000502:physiology; D014819:Vitellogenins / Q000096:biosynthesis*
D045166:Estradiol Congeners; D014819:Vitellogenins; D004997:Ethinyl Estradiol