Regional comparison of prolactin gene expression in the human decidualized endometrium in early and term pregnancy

Abstract

Prolactin (PRL) is known to be expressed in the decidualized human endometrium and secreted into amniotic fluid. Although the site of synthesis of endometrial PRL is known to be the decidual cells, the difference in PRL gene expression within each area of decidua, i.e. decidua basalis, decidua parietalis and decidua capsularis, during pregnancy is not clear. We have applied an in situ hybridization histochemistry technique using a radiolabeled RNA probe to compare the difference in expression of PRL gene within each area of the decidualized endometrium. Specific hybridization signals were distributed over the decidual cells in early and term pregnancy. More intense hybridization signals were always detected in the tissues of early pregnancy than in those of term pregnancy. In the decidua capsularis of early pregnancy, labeled cells were concentrated close to the amniotic cavity, whereas cells were concentrated close to the maternal surface of the fetal membrane in term pregnancy. In the decidua parietalis, almost all decidual cells were labeled, but no specific labeling was seen in the endometrial glands or capillary endothelium in both groups. In the decidua basalis, most decidual cells showed hybridization signals whereas no hybridization signal was seen over the trophoblast cells. These results show that there are regional and periodic differences in PRL gene expression in the decidual cells during pregnancy.

Increased T‐Cell Activation in Decidua Parietalis Compared to Decidua Basalis in Uncomplicated Human Term Pregnancy

“…Furthermore, prolactin receptors have been identified in the placenta and amnion 42 . It is suggested, yet not fully clear, that there are regional and periodic differences in prolactin gene expression in the decidual cells during pregnancy 43 . Perhaps there is increased prolactin expression in the decidua parietalis leading to T‐cell activation.…”

Regional Localization of Immunoreactive c-<i>fos</i> and Prolactin in Human Endometrium during the Normal Menstrual Cycle

“…As far as we know, this hypothesis remains to be explored, but there is indirect evidence to support it. Studies using in situ hybridization of placental tissue have shown that the PRL mRNA signal is restricted to stromal cells both in early and term decidua [21][22][23].…”

Relationship between the amniotic fluid prolactin level at early second trimester and pregnancy outcome

“…Decidual cells synthesize endometrial prolactin and some variations in prolactin gene expression were shown within each area of decidua. Study showed periodic differences in prolactin gene expression in the decidual cells during pregnancy (30).…”