Effects of trilostane and fipronil on the reproductive axis in an early life stage of the Japanese medaka (Oryzias latipes).
Given the critical role of the hypothalamic-pituitary-gonadal (HPG) axis, it is conceivable that perturbations at any point along this axis can potentially affect reproduction in fish and other vertebrates. We investigated the effects of a 3β-hydroxysteroid dehydrogenase (3β-HSD) inhibitor, trilostane (TRI), and a gamma-aminobutyric acid (GABA)-receptor antagonist, fipronil (FIP), on the HPG axis using an early life stage of the Japanese medaka. The newly hatched larvae were exposed to TRI (100, 300 and 1000 μg/L) and FIP (3, 10 and 30 μg/L), respectively, until 28 days post-hatching. Exposure to TRI decreased the body length in males, whereas FIP inhibited growth in both sexes. The induction of steroidogenesis-regulating genes (including 3β-hsd) in males exposed to TRI, accompanied by increased vtg and er transcription, indicating a compensatory response to the presumed 3β-HSD inhibition. These compensatory responses were not observed in TRI-treated females. Regarding FIP exposure, the GABA blocker resulted in the down-regulation of fshr and lhr. A compensatory up-regulation of steroidogenesis-regulating genes partially explained the elevated transcripts of vtg genes in both males and females after FIP exposure. These results suggest that both the inhibition of 3β-HSD and the antagonism of GABA receptors are relevant modes of endocrine disruption that could impact the normal regulation of the HPG axis.
College of Biological and Environmental Engineering, Zhejiang University of Technology, Hangzhou, 310032, People's Republic of China.
Liwei
L
Sun
Rong
R
Jin
Zuhua
Z
Peng
Qiwei
Q
Zhou
Haifeng
H
Qian
Zhengwei
Z
Fu
D000818:Animals; D013196:Dihydrotestosterone / Q000031:analogs & derivatives* / Q000633:toxicity; D005260:Female; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D008297:Male; D009990:Oryzias / Q000254:growth & development*; D011720:Pyrazoles / Q000633:toxicity*; D012098:Reproduction / Q000187:drug effects*; D012737:Sex Factors
D011720:Pyrazoles; D013196:Dihydrotestosterone; C009954:trilostane; C082360:fipronil