Relationship between physical activity and HDL-cholesterol in healthy older men and women: a cross-sectional and exercise intervention study

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.     

The sonographic finding of persistent umbilical cord cystic masses is associated with lethal aneuploidy and/or congenital anomalies

This study was designed to examine the expression of the prolactin receptor (PRL-R) gene in the human decidualized endometrium and to determine the localization of endometrial cells expressing the PRL-R gene. Method: Decidua and trophoblast tissues of normal and ectopic pregnancy were obtained by curettage from patients undergoing artificial abortion at 8 -10 weeks of gestation. Total RNA was extracted to perform northern blot hybridization with a radiolabeled human PRL-R cDNA probe. Some tissues were cut and processed for in situ hybridization histochemistry with a radiolabeled RNA probe. Results: 1. Northern blot hybridization: Approximately 9.0, 3.6 and 2.8kb size bands were detected in decidua in normal and ectopic pregnancy. No hybridization signal was detected in the chorionic villi. 2. In situ hybridization: Hybridization signals were detected in the cytoplasm of the decidual cells not only in normal pregnancy but also in ectopic pregnancy. No hybridization signal was detected in the trophoblast cells or endometrial glands. Conclusion: The human PRL-R gene is expressed in the decidual cells in early pregnancy not only in normal pregnancy but also in ectopic pregnancy. And it has been reported that the decidual cells produce PRL. These results suggest that PRL may act directly on the decidual cells by paracrine and/or autocrine mechanisms.     

Inhibition of gene expression by steroid hormone receptors via a negative glucocorticoid response element: evidence for the involvement of DNA-binding and agonistic effects of the antiglucocorticoid/antiprogestin RU486

We have used a negative glucocorticoid response element (nGRE) from the bovine prolactin promoter linked to the gene for chloramphenicol acetyltransferase (PRL3CAT) to study the inhibition of gene expression by steroid hormone receptors. This nGRE increased basal expression from a heterologous promoter in COS-7 cells. In the presence of cotransfected glucocorticoid (GR), androgen, or progesterone receptor (PR) expression vectors and their cognate ligands, the expression of PRL3CAT could be repressed, indicating that these steroid receptor subfamily members could function through the same negative response element. No repression was observed with the estrogen receptor, showing that the repressive effect was specific for members of the GR-subfamily. Mutation of three amino acids within the GR-DNA binding domain that determine the specificity of GR-GRE interaction abolished the ability of the GR to inhibit the expression of PRL3CAT, demonstrating the requirement for DNA binding of the GR in the mechanism of repression. The antiglucocorticoid/antiprogestin RU486 when bound to PR or GR also repressed the expression of the PRL3CAT, but higher concentrations of RU486 were required to obtain an effect with the GR when compared to the PR. RU486 was unable to antagonize the effect of progestins on PRL3CAT and only partially antagonized the glucocorticoid repression. Thus, regarding the repression of PRL3CAT, RU486 acted as an agonist when bound to the PR and as a partial agonist when bound to the GR.     

Biological mechanisms underlying the clinical effects of RU 486: modulation of cultured endometrial stromal cell stromelysin-1 and prolactin expression

During in vitro decidualization of human endometrial stromal cells (HESCs), medroxyprogesterone acetate (MPA) inhibits expression of the potent extracellular matrix (ECM)-degrading protease stromelysin-1 (MMP-3), but enhances PRL expression. Consistent with its priming role in vivo, estradiol (E2) augments these effects. In the current study, immunoblot analysis revealed that coincubation with 10(-6) M RU 486 blocked the inhibition in HESC-secreted MMP-3 levels (50,000 mol wt) evoked by 10(-8) M E2 + 10(-7) M MPA. Although MPA can act as a glucocorticoid, the HESCs were refractory to 10(-7) M dexamethasone added alone or with E2. Because E2 elevates progesterone but not glucocorticoid receptor levels, MPA and RU 486 control MMP-3 expression as a progestin and antiprogestin, respectively. To study RU 486 involvement in steroid withdrawal leading to menstruation, HESCs were decidualized during 10 days incubation with E2 + MPA, and parallel cultures were kept in E2 + MPA or withdrawn to either control or RU 486-containing medium. Compared with E2 + MPA-suppressed HESCs, increases in levels of secreted MMP-3 (2.0-fold), and its 2.1-kilobase messenger RNA (10-fold) were observed in HESCs after 4 days of withdrawal to control medium, with much greater increases seen in RU 486-containing medium (10-fold protein, 100-fold messenger RNA). Previously, we showed that RU 486 up-regulated E2 + MPA-inhibited plasminogen activator expression in the cultured HESCs. Extrapolation of these in vitro observations to endometrial events following RU 486 administration suggests that coordinate enhancement of MMP-3 and plasminogen activator expression promotes proteolysis of the stromal/decidual ECM, which leads to endometrial sloughing. Moreover, destabilization of endometrial microvessels resulting from degradation of their surrounding ECM is consistent with the heavy menstrual bleeding stemming from RU 486 administration. However, in contrast to the marked RU 486-initiated reversal of MMP-3 expression, RU 486 did not significantly reverse E2 + MPA-enhanced PRL secretion by the cultured HESCs. Interestingly, decidual PRL, unlike decidual MMP-3, does not appear to play a role in menstruation. Interleukin-1 beta counteracted E2 + MPA-mediated inhibition of secreted MMP-3 levels, implying that leukocyte/trophoblast-derived cytokines can modulate steroid-regulated MMP-3 expression by stromal/decidual cells during menstruation and pregnancy.     

Requirement for transglutaminase in progesterone-induced decidualization of human endometrial stromal cells

Differentiation of endometrial stromal cells (decidualization) is essential for embryo implantation and maintenance of pregnancy. By sequential complementary DNA subtractive hybridization, one of the messenger RNAs (mRNA) induced by progesterone in human endometrial stromal cells decidualized in vitro was identified as that of a tissue transglutaminase type II (TGase). TGase mRNA was induced within 6 h after the addition of progesterone to the culture, and the effect was dose dependent. Both the TGase inhibitor monodansylcadaverine and oligodeoxynucleotide complementary to the TGase mRNA inhibited the decidualization, as assessed by PRL production and morphological transformation. Expression of TGase mRNA in human decidua and endometria exposed to high levels of progesterone in vivo was demonstrated by Northern blotting and in situ hybridization. These data suggest that TGase is necessary for the decidualization of human endometrial stromal cells and that clarification of the mechanism of action of TGase will facilitate further insight into the diagnosis and treatment of infertility.