SYNTHESIS OF GAP JUNCTION PROTEINS AND COLLAGENASES IN THE PREIMPLANTATION RAT UTERUS

Synthesis of gap junction proteins (GJPs) and of collagenases in the r at uterus has been studied under two physiological conditions: various stages of the estrus cycle, and the early pregnangy period. The synth esis has been studied by incubating uterine horns in a short-term tiss ue culture medium containing radioactively-labeled amino acids, follow ed by a double antibody immunoprecipitation of the labeled proteins. A fter exposure of the media to either anti-collagenase IgG(s) or anti-G JPs IgG(s), the final immunoprecipitation was achieved with the use of goat anti-rabbit IgG. Collagenase (s) synthesis was found to reach th e peak, during the estrus cycle, at the proestrus stage, while GJP syn thesis reached the maximum during the estrus stage. In the preimplanta tion, pregnant, rat uterus the syntheses of both the proteins reached the respective peak activities on day 4 of pregnancy about 24 h before the expected time of ovum implantation. A study of the literature rev eals that this time coincides with a spurt in exposure of the progeste rone dominated uterus to estradiol.