Date of this Version
Published in Domestic Animal Endocrinology 23 (2002) 383–396.
Granulocyte macrophage-colony stimulating factor (GM-CSF) increases ovine interferon-tau (oIFNτ) secretion by ovine conceptuses, but endometrial production of GM-CSF has not been characterized. Endometrial GM-CSF expression was evaluated in ovariectomized ewes implanted with estradiol-17β (E2) and/or progesterone (P4) for 14 days, in day 14 cyclic and day 14 pregnant ewes. Relative levels of endometrial GM-CSF mRNA were 3-fold higher in E2- and E2/P4-treated ewes than that of control or P4-treated ovariectomized ewes. Levels of endometrial GM-CSF mRNA for cyclic ewes were similar to E2- and E2/P4-treated ewes, but amounts of GM-CSF mRNA in pregnant ewes were 2-fold higher. GM-CSF concentrations in endometrial culture media, determined by GM-CSF bioassay, for cyclic and E2/P4-treated ovariectomized ewes were 3-fold higher than those of control, E2- and P4-treated ovariectomized ewes; however, amounts of GM-CSF in pregnant ewes were 2-fold higher. Immunoreactive GM-CSF, examined by western blot, was detected in the culture medium from E2/P4-treated ovariectomized, cyclic and pregnant ewes. Luminal and glandular epithelia and stromal regions were determined to be sites of GM-CSF expression by immunohistochemistry and in situ hybridization techniques. Data indicate that combined E2 and P4 treatment of ovariectomized ewes is sufficient to restore GM-CSF expression to the level found in cyclic ewes; however, GM-CSF mRNA and protein in pregnant ewes is 2-fold greater than in ovariectomized or cyclic ewes. These data suggest that the conceptus, in addition to steroids, may play a role in the regulation of endometrial production of GM-CSF.