Early Synthesis of Uterine Proteins After a Decidual Stimulus in the Pseudopregnant Rat

Abstract

The synthesis of soluble proteins in the uterus of the pseudopregnant rat after decidual induction was examined using polyacrylamide electrophoresis with double-labeling incorporation of amino acids. Incorporation of [3H]-leucine into soluble proteins showed that the endometrial tissue synthesized a single protein band 1 h after the decidual stimulus. This protein migrated ahead of the bulk of the proteins and slightly faster than serum albumin during the 6% polyacrylamide electrophoresis. The protein(s) did not show up when the whole uterus was examined 1, 2, 3, 4 and 5 h after decidual induction nor in the endometrium on day L3 of pseudopregnancy, the day on which uterus was insensitive to the decidual stimulus. This protein may be synthesized only when the endometrial cells differentiated to form the decidual tissue. The antimesometrial region of the endometrium previously subjected to the decidual stimulus seemed to show a higher capacity to synthesize this protein than in the mesometrial region of the same stimulated tissue.