CHANGES IN ALPHA(1-2)-FUCOSYL-TRANSFERASE ACTIVITY IN THE MURINE ENDOMETRIAL EPITHELIUM DURING THE ESTROUS-CYCLE, EARLY-PREGNANCY, AND AFTER OVARIECTOMY AND HORMONE REPLACEMENT

alpha(l-2)-Fucosyltransferase (alpha(l-2)-FT) activity in the uterine luminal epithelium was investigated during the estrous cycle, during early pregnancy, and in ovariectomized mice treated with ovarian steroids. Phenyl-beta-D-galactoside was used as a specific acceptor for alpha(1-2)-FT activity. Enzyme activity fell dramatically throughout the pre- and peri-implantation period (Days 1-6 of pregnancy). Activity on Day 4 of pregnancy represented less than a tenth of the Day 1 level and by Day 6 became undetectable. During the estrous cycle alpha(1-2)-FT showed a peak of activity at estrus, the level being similar to that observed on Day 1 of pregnancy. In proestrus, postestrus, and diestrus, activity was similar and was approximately one Mh of that during estrus. Ovariectomized mice were primed with estrogen and treated with progesterone only, estradiol benzoate only, or progesterone followed by a single injection of progesterone and estradiol. Estrogen alone stimulated alpha(l-2)-FT activity, while progesterone treatment was strongly inhibitory. These results correlate well with the pattern of expression of the fucosylated H-type-l carbohydrate epitope found on the endometrial epithelium and believed to have a role in implantation. alpha(1-2)-FT is capable of catalying the final step in formation of the H-type-1 oligosaccharide, and on the basis of our results it is likely that control of this enzyme is the major factor responsible for modulating H-type-l expression.