Effect of Pregnant Mare’s Serum (PMS) on RNA Polymer ase Activity and Protein Synthesis in Ovaries of Immature Rats1

Abstract

There is considerable evidence which indicates that gonadotropins influence ovarian tissue at the level of protein and nucleic acid synthesis. In the present study the amounts of nucleic acids and protein and the activity of RNA polymerase in the ovaries of immature rats were determined at intervals during 48 hr. following a single injection of pregnant mare''s serum gonadotropin (PMS). Increases in ovarian weight, RNA and protein content were detectable after 6 hr. and continued in more or less parallel fashion during the time of study. DNA did not exhibit a significant increase until 12-18 hr. after PMS administration. The specific activity of RNA polymerase increased measurably in 3 hr. reached a peak in 12 hr. and declined thereafter at a time when the RNA content continued to increase markedly. Possible interpretations of these findings are indicated. Cycloheximide administered in vivo markedly inhibited the in vitro activity of the enzyme and the in vivo synthesis of RNA,.