John Wiley & Sons, Ltd.

Endocrine disruption by di‐(2‐ethylhexyl)‐phthalate (DEHP) in Chinese rare minnow (Gobiocypris rarus)

Great concern has been raised over the potential impact of environmental contaminants on fish populations that inhabit in the Three Gorge Reservoir (TGR). In the present study, we investigated the endocrine disrupting effects of di‐(2‐ethylhexyl)‐phthalate (DEHP), on the Chinese rare minnow (Gobiocypris rarus), an endemic fish distributing upstream waters in the Yangtze River. Adult rare minnow were exposed to environmentally relevant concentrations of DEHP (0, 3.6, 12.8, 39.4 and 117.6 µg/L) for a 21‐d period. Then concentrations of sex hormones in the plasma and relative transcription of various associated genes were measured in the hypothalamic–pituitary–gonadal (HPG) axis and liver of the fish. Exposure to DEHP resulted in greater circulating concentrations of testosterone (T) and lower concentrations of estradiol (E2), which was accompanied by up‐regulation of Cyp17 mRNA and down‐regulation of Cyp19a mRNA in the gonads of females. In males, increases of T and E2 levels were consistent with up‐regulation of Cyp17 and Cyp19a in the gonads. Furthermore, the T/E2 ratio was increased in females but reduced in males. A significant increase in the levels of hepatic vitellogenin (VTG) gene transcription was observed in both females and males. The present study showed that waterborne exposure to DEHP altered plasma sex hormone levels and modulated gene transcription profiles of associated genes in the HPG axis and liver, mostly occurred at higher concentrations (> 39.4 μg/L), which suggest that environmental concentration of DEHP (5.4 μg/L) alone may not likely disturb endocrine system of rare minnow in the Three Gorge Reservoir. Environ Toxicol Chem © 2013 SETAC

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