[Expression of prolactin gene in human decidua]

This study was designed to detect the localization of prolactin gene expressing cells in the human utero-placental unit during pregnancy.

Human endometrium was obtained at hysterectomy from normally cycling women who underwent surgery for myoma uteri. Decidual and trophoblast tissues from early pregnancy were obtained by curettage from patients undergoing therapeutic abortion at 8-10 weeks of gestation. Term placenta was obtained from patients with uncomplicated deliveries at 38-40 weeks. Total RNAs of these tissues were extracted to perform Northern blot hybridization (NBH) with the radiolabelled human pituitary prolactin cDNA probe. Frozen sections of these tissues were cut and processed for in situ hybridization (ISH) with the radiolabelled RNA probe complementary for human prolactin mRNA.

1. By NBH, approximately a 1.3 kilobase (kb) size band was detected in the total RNA obtained from late secretory endometrium (day 26), decidua of early pregnancy and placenta of term pregnancy, and the decidua had the most significant signal. No hybridization signal was detected in the chorionic villi in early pregnancy. 2. By ISH, a significant hybridization signal was detected in the cytoplasm of the decidual cells in early and term pregnancy. No hybridization signal was detected in the endometrial grandsand trophoblast cells.

These results indicate that prolactin is synthesized in the decidual cells in the human uterus during pregnancy.