Abstract
This research examined the gene expression profile of three goldfish estrogen receptor (ER) subtypes in multiple tissues in relation to mRNA levels of aromatase B and vitellogenin (VTG) following waterborne estrogen exposures. The protocol consisted of: i) adult male goldfish in late gonadal recrudescence exposed to 1 nM 17β-estradiol (E2); ii) adult male and female goldfish in early sexual regression exposed to 1 nM E2 for 3, 6, 12 and 24 h; and, iii) sexually mature, adult male goldfish exposed to 0.3 nM 17α-ethynylestradiol (EE2) for 24 h. Liver produced the most consistent response with up-regulation of ERα in sexually regressed, mature and recrudescing males and in sexually regressed females. The dose and length of exposure, reproductive state and sex affected the auto-regulation of ERβ1 by E2. ERβ2 was not affected in any experiments suggesting it may not be auto-regulated by E2. Aromatase B and VTG gene expression were affected by E2, but also by other experimental conditions. EE2 induced liver ERα and VTG mRNA levels indicating that high environmental EE2 levels induce E2-mediated gene expression in a model teleost. These studies reveal a more complicated action of estrogenic compounds that has important implications on estrogenic endocrine disruptors in teleosts.
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