Abstract
Summary
The influence of thyroxine on the incorporation of uridine-3H into uterine acid soluble and RNA fractions and on nuclear RNA polymerase activity of ovariectomized-thyroidectomized rats was studied. The incorporation of uridine-3H into uterine RNA of untreated ovariectomized-thyroidectomized rats was higher than that of untreated ovariectomized rats which was further elevated by thyroxine and 17β-estradiol administration. A potentiating effect was observed following the administration of both hormones which was inhibited by actinomycin D.
The uterine nuclear RNA polymerase activity of untreated ovariectomized-thy-roidectomized rats was higher than that of ovariectomized rats. Thyroxine administered to ovariectomized-thyroidectomized rats depressed the polymerase activity and 17β-estradiol administration of these rats did not influence the polymerase activity. The results of the present study suggest that thyroxine influences uterine RNA synthesis and potentiates the stimulatory effect of 17β-estradiol.
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