Me. Mackay et al., UP-REGULATION OF ESTROGEN-RECEPTOR MESSENGER-RNA AND ESTROGEN-RECEPTOR ACTIVITY BY ESTRADIOL IN LIVER OF RAINBOW-TROUT AND OTHER TELEOSTEANFISH, Comparative biochemistry and physiology. Part C, Pharmacology toxicology & endocrinology, 115(3), 1996, pp. 201-209
Injection of estradiol (E(2)) into immature rainbow trout resulted in
the induction of the hepatic vitellogenin gene mediated by the nuclear
estrogen receptor (ER). Liver ER mRNA rose markedly on E(2) treatment
in three groups of trout kept at different temperatures. Only in the
group kept at 4 degrees C did the total cellular ER, as measured by [H
-3]estradiol-binding activity in nuclear and cytosol fractions, parall
el the ER mRNA level. In fish kept at 9 degrees C and 15 degrees C, th
e ratio of total ER activity to ER mRNA fell during chronic E(2) treat
ment, probably reflecting translational or post translational control
mechanisms. Upregulation of ER mRNA also occurred in sea raven, sculpi
n, winter flounder, and Atlantic salmon after E(2) treatment. Intrahep
atic ER activity rose proportionately in Atlantic salmon kept at 6-9 d
egrees C but not in sea raven, sculpin, or flounder. We conclude that
the regulation of ER expression in teleosts is complex and includes tr
anscriptional, translational, and posttranslational elements and is in
fluenced by environmental temperature. Copyright (C) 1996 Elsevier Sci
ence Inc.