Progesterone regulation of endometrial estrogen receptor and cell proliferation during the late proliferative and secretory phase in artificial menstrual cycles in the rhesus monkey

Progesterone (P) down-regulation of uterine estradiol (E) receptor (ER) appears to be a general mechanism by which P modulates E action in the uterus. Our present studies focus on the regulation of ER by P during the changeover from E to P dominance during artificial menstrual cycles in the rhesus monkey. Because of differential cell-type response and the cellular zonation of the primate uterus, we used immunohistochemical analysis in addition to biochemical assays to study the regulation of ER by P. Ki-67 immunoreactivity was used as an index of endometrial proliferation. We performed our analyses on Days 13 (peak of E), 14 (declining E and rising P), 17 (basal E and rising P), and 21 (basal E and peak P). ER immunoreactivity was present throughout the endometrium in luminal and glandular epithelia and stromal fibroblasts on Day 13. As E was withdrawn and P rose on Day 14 there were few distinct changes in ER staining in stromal and epithelial cells. On Day 17, immunoreactive staining showed a distinct reduction for stromal cells in all zones. Although luminal epithelial cells showed a decrease in immunoreactivity on Day 17, zones II, III, and IV retained positive staining for ER in glandular epithelia. ER staining in stromal cells on Day 21 was similar to the pattern observed on Day 17, whereas epithelial cells in zones I, II, and III showed a reduction in staining. Glandular epithelia in zone IV maintained strong positive staining for ER on Day 21.(ABSTRACT TRUNCATED AT 250 WORDS

Analysis of differential gene regulation in adequate versus inadequate secretory-phase endometrial complementary deoxyribonucleic acid populations from the rhesus monkey

The ability to create artificial menstrual cycles in the rhesus monkey provides a model for studies on the regulation of genes and gene networks by estradiol or progesterone (P) in the primate endometrium. This model allowed us to create both a normal level of secretory phase P or an inadequate level of secretory phase P, i.e. endometria that cannot support implantation. The objective of our present study focused on PCR analyses of genes for several factors that are believed to be important in the proper maturation of the endometrium. Complementary DNA (cDNA) populations were prepared from endometria harvested on day 13 (peak E level), days 21-23 of an adequate secretory phase (PcDNA) and days 21-23 of an inadequate secretory phase (IcDNA). Although placental protein 14, leukemia inhibitory factor and 17-beta hydroxysteroid dehydrogenase displayed highly upregulated levels in PcDNA (P-activated genes), there was little or no up-regulation in IcDNA. Transforming growth factor-beta 2 and its receptor and insulin growth factor-I and its receptor were up-regulated in PcDNA, whereas little or no expression was observed in IcDNA. Regulators of the cell cycle and transcription, such as retinoblastoma, c-fos, and c-jun genes, were also greatly underexpressed in IcDNA compared with PcDNA. Interestingly, one gene that we studied, keratinocyte growth factor, that was up-regulated by P (peak E levels vs. PcDNA) was more highly expressed in IcDNA. This latter result suggests that low levels of circulating P are sufficient for expression of this gene, whereas high sustained P levels result in an autologous down-regulation. These data show that the regulation of genes that may play pivotal roles in endometrial maturation are differentially expressed in IcDNA vs. PcDNA and may, in part, characterize improper endometrial maturation