Expression of progesterone receptor mRNA in the endometrium during the normal menstrual cycle and in Norplant users
Lau, T.M.; Witjaksono, J.; Affandi, B.; Rogers, P.A.
Human Reproduction 11(12): 2629-2634
1996
ISSN/ISBN: 0268-1161 PMID: 9021364 DOI: 10.1093/oxfordjournals.humrep.a019183Document Number: 305248
At Monash Medical Center in Victoria, Australia, and at the University of Indonesia in Jakarta, researchers used digoxigenin-labeled ribonucleic probes for in-situ hybridization in the endometrium of 53 women across the normal menstrual cycle (controls) and of 39 Norplant users (cases), respectively, to examine the expression of progesterone receptor mRNA in the endometrium during the normal menstrual cycle and in Norplant users. They detected progesterone receptor mRNA in the glandular epithelium and stromal cells at all stages of the menstrual cycle. Concentrations of progesterone receptor mRNA staining in the glands increased from stage 1 (the menstrual to early proliferative stage), when there was little progesterone receptor mRNA staining, to stage 2 (early-to-mid proliferative to late proliferative stage) (1.35 vs. 2.25 staining intensity score; p 0.01). Thereafter, they fell steadily, but not significantly so. On the other hand, concentrations of progesterone receptor mRNA staining in the stroma did not vary during the menstrual cycle. Most endometria of Norplant users had detectable progesterone receptor mRNA in both the glandular epithelia and stromal cells. The endometria of Norplant users had less progesterone receptor mRNA staining in glandular epithelia than stage 2 of the cycle of the controls (1.5 vs. 2.25 score; p 0.01). The Norplant stroma also had less progesterone receptor mRNA than stages 2 (1.75 vs. 2.5 score; p 0.05) and 3 (1.75 vs. 2.5 score; p 0.01). Among Norplant users, the amenorrhea group had more progesterone receptor mRNA staining in the stroma than the bleeding group (2.5 vs. 1.75 score; p 0.05). It had lower plasma concentrations of estrogen than the bleeding group (200.8 vs. 523.9 pmol/l; p 0.05). There were no differences in the plasma progesterone concentrations, however. These findings confirm that there is a significant relationship between reduced endogenous estrogen concentrations and reduced breakthrough bleeding in users of progestin-only contraceptives. They show that glandular and stromal progesterone receptors have different sensitivity to steroid regulation.