In vivo modulation of 17 beta-estradiol-induced vitellogenin synthesis and estrogen receptor in rainbow trout (Oncorhynchus mykiss) liver cells by beta-naphthoflavone.
Vitellogenesis or egg yolk production represents a key estrogen initiated process in oviparous vertebrates which is crucial for oocyte maturation. Previous in vitro studies have shown that cytochrome P4501A1 (CYP1A1)-inducing compounds such as beta-naphthoflavone (betaNF) modulate 17 beta-estradiol-induced vitellogenin (Vg) synthesis in primary cultures of juvenile rainbow trout liver cells. In this study, treatment of juvenile trout with 0.5 mg/kg 17 beta-estradiol plus either 25 or 50 mg/kg betaNF confirmed in vivo that betaNF may depress Vg synthesis by the liver. Alternatively, trout treated with 0.5 mg/kg 17 beta-estradiol plus 12.5 mg/kg betaNF or 5 mg/kg 17 beta-estradiol plus 12.5, 25, or 50 mg/kg betaNF showed a potentiation of Vg synthesis relative to estradiol-only injected fish. These results are significant as they suggest that changing plasma estrogen levels in sexually maturing trout will determine whether or not CYP1A1-inducing compounds may suppress, have no effect, or potentiate estrogen-induced liver Vg synthesis. Depressed Vg synthesis by trout injected with 0.5 mg/kg 17 beta-estradiol plus 50 mg/kg of betaNF correlated with depressed estrogen-binding capacity of liver, as assessed by [3H]17 beta-estradiol binding to liver nuclear protein extracts. Using gel mobility shift assay, the decrease in estrogen responsiveness of liver was not attributed to depressed estrogen response element-estrogen receptor binding. The fish liver vitellogenesis process offers a comparative model with which to further study the mechanism(s) of aryl hydrocarbon receptor-mediated antiestrogenicity and endocrine disruption.
Anderson
M J
MJ
Department of Anatomy, Physiology and Cell Biology, School of Veterinary Medicine, University of California, Davis 95616, USA.
Olsen
H
H
Matsumura
F
F
Hinton
D E
DE
D000818:Animals; D001483:Base Sequence; D001571:Benzoflavones / Q000494:pharmacology*; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D004958:Estradiol / Q000378:metabolism* / Q000494:pharmacology*; D005260:Female; D007700:Kinetics; D008099:Liver / Q000187:drug effects* / Q000378:metabolism* / Q000648:ultrastructure; D008297:Male; D008969:Molecular Sequence Data; D017686:Oncorhynchus mykiss / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000187:drug effects* / Q000378:metabolism*; D014316:Tritium; D014819:Vitellogenins / Q000096:biosynthesis*; D019324:beta-Naphthoflavone
D001571:Benzoflavones; D011960:Receptors, Estrogen; D014819:Vitellogenins; D014316:Tritium; D004958:Estradiol; D019324:beta-Naphthoflavone; D003577:Cytochrome P-450 Enzyme System