Mechanism of Action of the Sex Steroid Hormones

Effects of Sex Steroid Hormones on RNA MetabolismEstrogenUterine RNA synthesis is stimulated by estrogen. The promptest response was observed in the synthesis of the rapidly labeled nuclear RNA.^{105, 122} A definite stimulation of nuclear RNA synthesis within 10 minutes after an intraperitoneal injection of estradiol has been reported.¹²² The rapidly labeled nuclear RNA was also examined by sucrose gradients under both ordinary and denaturing conditions (to exclude aggregation)¹²³ and was shown to be of high molecular weight and hence consistent with heterogeneous nuclear RNA.^{123 , 124} That the early increase in nuclear RNA synthesis is blocked by actinomycin D but not . . .