Immunoreactive (ir)-Transforming Growth Factor (TGF)-β in Rat Corpus Luteum

ir-TGFβ Is Expressed by Luteal Macrophages

Abstract

Western analyses and immunohistochemistry of transforming growth factor β1(TGFβ1) and TGFβ2 were performed in rat luteal tissue at either the functional or regressing stage. Anti-TGFβ1 or TGFβ2 was localized simultaneously to macrophages within cultured luteal cells and frozen ovarian sections. By Western analysis, an active form of TGFβ (25kDa) was detected clearly with anti-TGFβ2 but only faintly with anti-TGFβ1, and the former band from functional corpora lutea was more intense than that from regressing ones. Treatment with prolactin (PRL), a luteotropic hormone in rodents, also increased the intensity of 25kDa TGFβ2 in the corpus Luteum. Several specific bands with higher molecular weights than 25kDa were also recognized with anti-TGFβ1 or TGFβ2; they are probably ascribed to latent TGFβs and/or TGFβ precursor proteins. In cultured luteal cells and frozen ovarian sections, many anti-TGFβ1 or anti-TGFβ2 positive cells from functional corpora lutea of pseudopregnant rats were double-stained with anti-macrophage. There were numerous macrophages in structurally regressing corpora lutea of pseudopregnant rats, but most of them were not stained with anti-TGFβs. These results suggest that the expression of TGFβ, at least for TGFβ2, is under the influence of PRL in the rat corpora lutea, and that macrophages are responsible for some, if not all, of the Immunoreactive-TGFβ in rat luteal tissue.