Selective inhibitory effects of thyroid hormones on estrogen-induced protein synthesis in chick embryo liver.
We have investigated the effect of thyroid hormones on estrogen-induced responses in embryonic chick liver. Administration of thyroid hormones inhibits estrogen induction of vitellogenin, as well as of apoprotein-II of very low density lipoprotein (VLDL apo-II). A proportionate decrease in the concentration of hepatic salt-soluble nuclear estrogen receptor is also observed. In contrast, estrogen stimulation of apoprotein-B (VLDL apo-B) synthesis is relatively resistant to inhibition. The inhibitory effects of the thyroid hormones could be due to increased metabolism and clearance of estradiol-17 beta in their presence. The relative resistance of estrogen-induced VLDL apo-B synthesis to thyroid hormone inhibition can be explained by its greater sensitivity to low doses of estradiol. In addition, experiments with the antithyroid agent thiourea suggest that, in vivo, estrogen-induced responses could be balanced by the selective inhibitory effects of thyroid hormones.
D000818:Animals; D001053:Apolipoproteins / Q000096:biosynthesis*; D002467:Cell Nucleus / Q000378:metabolism; D002642:Chick Embryo; D004958:Estradiol / Q000494:pharmacology; D006131:Growth Inhibitors / Q000494:pharmacology*; D008079:Lipoproteins, VLDL / Q000096:biosynthesis*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D011960:Receptors, Estrogen / Q000187:drug effects; D013890:Thiourea / Q000494:pharmacology; D013963:Thyroid Hormones / Q000494:pharmacology*; D014284:Triiodothyronine / Q000494:pharmacology; D014819:Vitellogenins / Q000096:biosynthesis*
D001053:Apolipoproteins; D006131:Growth Inhibitors; D008079:Lipoproteins, VLDL; D011960:Receptors, Estrogen; D013963:Thyroid Hormones; D014819:Vitellogenins; C027610:apolipoprotein VLDL II; D014284:Triiodothyronine; D004958:Estradiol; D013890:Thiourea