Dynamics of estrogen biomarker responses in rainbow trout exposed to 17beta-estradiol and 17alpha-ethinylestradiol.
We have investigated the response dynamics of the estrogen-dependent genes vitellogenin (VTG) and the vitelline envelope proteins (VEPs) as well as circulating VTG in immature female rainbow trout (Oncorhynchus mykiss) exposed to 17beta-estradiol (E2) and 17alpha-ethinylestradiol (EE2) for periods of 7 and 14 d. Gene responses were quantified by measurement of messenger RNA (mRNA) in liver extracts using a chemiluminescent hybridization protection assay. Circulating VTG was measured by a homologous enzyme-linked immunosorbent assay. Exposure to both E2 and EE2 induced concentration-dependent increases in all biomarkers. The data presented indicate that VEP genes may be more sensitive to estrogens than the VTG gene. The biomarker lowest-observed-effect concentrations (biomarkerLOEC) in the 14-d study with E2 were 14 ng/L (VTG protein, VTG mRNA, VEPbeta, and VEPgamma) or 4.8 ng/L (VEPalpha). The EE2 was 5- to 66-fold more potent depending on the biomarker studied. In the 7-d study, all biomarkers were elevated after 48-h exposure to E2, with biomarkerLOECs of 30 ng/L (VTG protein, VTG mRNA, and VEPgamma) or 9.7 ng/L (VEPalpha and VEPbeta). Vitellogenin mRNA was induced up to 1,000-fold above baseline, and this translated into an increase of approximately 50,000-fold in circulating VTG. In conclusion, all biomarkers responded to estrogen exposure at environmentally relevant concentrations.
Thomas-Jones
Emma
E
Molecular Light Technology Research, Cardiff Industrial Park, Cardiff, CF14 5DL, United Kingdom.
Thorpe
Karen
K
Harrison
Nicola
N
Thomas
Gethin
G
Morris
Ceri
C
Hutchinson
Thomas
T
Woodhead
Stuart
S
Tyler
Charles
C
D000818:Animals; D001681:Biological Assay / Q000379:methods; D004703:Endocrine System / Q000187:drug effects; D004958:Estradiol / Q000633:toxicity*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D008099:Liver / Q000737:chemistry; D008163:Luminescent Measurements; D017686:Oncorhynchus mykiss / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D014819:Vitellogenins / Q000032:analysis / Q000096:biosynthesis*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
D012333:RNA, Messenger; D014819:Vitellogenins; D014874:Water Pollutants, Chemical; D004958:Estradiol