Effects of 4-nonylphenol on reproduction of Japanese medaka, Oryzias latipes.
We exposed mature Japanese medaka (Oryzias latipes) to 4-nonylphenol (4-NP) to elucidate its reproductive effects and estrogenic responses. For each treatment, eight breeding pairs were exposed for 3 weeks at measured 4-NP concentrations of 24.8, 50.9, 101, and 184 micrograms/L. Egg production of the pairs during the third week of exposure (15-21 d) was significantly decreased in the > or = 101-microgram/L treatment group, and fertility was significantly decreased in the 184-microgram/L group. Induction of testis-ova was observed in male fish at all 4-NP concentrations, whereas abnormality of spermatogenesis was found only in those receiving the 184-microgram/L treatment. The gonadosomatic index of the males in the 184-microgram/L group was also remarkably reduced. Hepatic vitellogenin (VTG) levels were significantly increased in both sexes receiving 4-NP treatments of > or = 50.9 micrograms/L. Overall, the lowest-observed effective concentrations (LOECs) of 4-NP for decreasing reproductive capacity (fecundity and fertility) and eliciting estrogenic responses (induction of testis-ova and VTG) were 101 and < or = 24.8 micrograms/L, respectively. The LOEC for reduced reproduction in medaka was at least four-fold greater than that required to elicit estogenic responses in male fish. Thus, we suggest that the estrogenic responses expressed in male fish are not responsible for the reduction in reproductive capacity.
Kang
Ik Joon
IJ
Division of Bioresource and Bioenvironmental Sciences, Kyushu University Graduate School, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581, Japan. kangnew@agr.kyushu-u-ac.jp
Yokota
Hirofumi
H
Oshima
Yuji
Y
Tsuruda
Yukinari
Y
Hano
Takeshi
T
Maeda
Masanobu
M
Imada
Nobuyoshi
N
Tadokoro
Hiroshi
H
Honjo
Tsuneo
T
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005298:Fertility / Q000187:drug effects*; D008297:Male; D009990:Oryzias / Q000502:physiology*; D010053:Ovary / Q000187:drug effects* / Q000254:growth & development*; D010636:Phenols / Q000633:toxicity*; D012737:Sex Factors; D013737:Testis / Q000187:drug effects* / Q000254:growth & development*; D014819:Vitellogenins / Q000032:analysis
D010636:Phenols; D014819:Vitellogenins; C041594:4-nonylphenol