The expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) and its regulation by ovarian steroids in rat uterine stromal cells

The effects of ovarian steroids on the expression of granulocyte-macrophage colony-stimulating factor (GM-CSF) in rat uterus were examined. Intense ex pression of GM-CSF mRNA was dispersedly located in the endometrial-myometri al junction and stroma of the uterus. GM-CSF was immunohistochemically loca lized in stromal cells and luminal epithelium. Ovariectomy significantly re duced the appearance of GM-CSF-mRNA-positive cells and the levels of expres sion for GM-CSF mRNA in the whole uterus, whereas treatment with 17 beta-es tradiol (E-2) or a combination of E-2 and progesterone (P-4) for 5 days on ovariectomized animals recruited GM-CSF-mRNA-positive cells and stimulated its expression. The combined treatment with E2 and Pq also stimulates the e xpression for GM-CSF mRNA and the production of immunoreactive GM-CSF in th e stromal tissues. These data suggest that the expression of GM-CSF in uter ine stromal cells is partially regulated by ovarian steroids.