Metabolism of Nucleic Acids

A radioautographic study of the inhibitory influence of repeated injections of estrone on cell division of the uterine epithelium of mice

“…They therefore advanced the hypothesis that there is in the organism a system of "estrogenic buffers" of a steroid nature. As other inves.tigators have shown [9], in the endometrium and in many tissues estrone is able to transform only 17 beta-estradiot, and conversely,neither the one compound nor the other can be transformed either into estradiol or into 17 alpha-estradioL Finally there remains the important possibility Of a direct action of estrone on many mechanisms regulating the several stages of formation of the precarsors of DNA by a kind of negative feed-back [6]. As other inves.tigators have shown [9], in the endometrium and in many tissues estrone is able to transform only 17 beta-estradiot, and conversely,neither the one compound nor the other can be transformed either into estradiol or into 17 alpha-estradioL Finally there remains the important possibility Of a direct action of estrone on many mechanisms regulating the several stages of formation of the precarsors of DNA by a kind of negative feed-back [6].…”

“…In our case it was less likely that there was any indirect transforma.tion Of estrone which is an active estrogen, into an inactive form such as, for example, 17 atpha-estradiol which inhibits the ability of 17 beta-esuadiot to activate the dehydrogenase of isocitric acid in the endometrium [14]. The reduced trip-phosphopyridine nucleotide is in turn able to catalyze the reduction of ribose to desoxyribose, which in turn leads to an increase in the intracellular pool of DNA precursors; however/the large amount of tdphosphates of certain o~er nucle0sides formed suppress this reaction, and DNA synthesis ceases [6]. Recently [10, 11] a considerable part has been assigned to estrogens as activators of the transdehydrogenases respomible for the transfer of hydrogen to the system of di-and tri-phosphopyridine nucleotides.…”