Biology of Reproduction, Vol 11, 421-428, Copyright © 1974 by Society for the Study of Reproduction

Effects of Actinomycin D and Puromycin on Blastokinin Synthesis by the Rabbit Uterus

¹ Department of Zoology, University of Tennessee, Knoxville, Tennessee 37916

Actinomycin D and puromycin were administered to mature rabbits during the first 5 days of their pregnancy to determine whether induction of blastokinin synthesis occurs at the transcriptional or translational level. Actinomycin D and puromycin both inhibit the production of blastokinin in pregnant rabbits. The disappearance of blastokinin after treatment with actinomycin D indicates that the continual synthesis of new RNA is necessary for the synthesis of blastokinin. Blastokinin requires continual RNA and protein synthesis during the peak of its secretion into uterine fluids of pregnant rabbits. Other proteins such as albumin may be superinduced by actinomycin D since total protein in the uterine flushings is higher in actinomycin D-treated animals than in controls. Puromycin tends to repress synthesis of all proteins in 5-day pregnant rabbit uterine flushings but does not completely repress blastokinin. Thus, while their effects on total protein production are greatly different, both antibiotics inhibit blastokinin synthesis. We conclude that induction of blastokinin synthesis operates at the transcriptional level.