Progesterone Action: Regulation of Avidin Biosynthesis by Hen Oviductin Vivoandin Vitro

The role of progesterone in regulating avidin synthesis in the magnum of the chick oviduct was studied both in vivo and in vitro. In estrogen pretreated animals, after a single injection of progesterone in oil, avidin became measurable at 10 hr and oviduct avidin content reached a maximum by 20 hr. Oviduct ovalbumin and lysozyme content were not affected. Although estrogen alone could not stimulate avidin synthesis, it acted synergistically with progesterone to produce a doubling of the induced level. Incubation of oviduct magnum minces pretreated with estrogen and progesterone resulted in a linear increase of avidin content for 72 hr. Added avidin was stable in vitro, declining only 10%/day. Avidin induction was inhibited by cycloheximide. Actinomycin D inhibited avidin biosynthesis by 50% or more under conditions where total protein synthesis was unaffected. The data suggest that progesterone acts in the hen oviduct to induce the synthesis of new avidin molecules. (Endocrinology83: 11, 1968)