Early Actions of Prolactin on Uridine Metabolism in Mammary Gland Explants1

Publisher Website
Google Scholar
Abstract
Studies were carried out to demonstrate the time—course for the prolactin stimulation of uridine incorporation into RNA in mammary gland explants obtained from 12– or 13–day pregnant Balb C mice. After preincubating tissues for 1, 2 or 3 days in medium containing insulin and hydrocortisone, it was discovered that a 3–4 hr incubation period with prolactin was required before a stimulation of uridine incorporation into RNA was demonstrable. Several experiments were carried out which indicated that the apparent delayed effect of prolactin on RNA synthesis is not due to the time required for the hormone to become distributed within the tissues. In one experiment explants were preincubated with prolactin for 24 hr at 0 C. This preincubation period was used in order for prolactin to become distributed within the tissues under conditions where metabolism was suppressed. After the 0 C preincubation the time—course for the effect of prolactin on RNA synthesis at 37 C was determined. Since the delayed effect of prolactin on RNA synthesis persisted under these circumstances, it was concluded that ongoing metabolism is required during the 3–4 hr lag time in order for prolactin to express its effect on RNA synthesis. The nature of these required metabolic processes is not known for certain. Experiments were also carried out in which an effect of prolactin on uridine transport in mammary gland explants was demonstrated. Further, it was shown that the time—course for the onset of this effect is similar to that for the stimulation of RNA synthesis. It is indeed possible that these two metabolic effects are coupled in some manner. (Endocrinology92: 1673, 1973)

This publication has 0 references indexed in Scilit: