QUANTITATIVE GONADOTROPIN-RELEASING-HORMONE GENE-EXPRESSION AND IMMUNOHISTOCHEMICAL LOCALIZATION IN HUMAN ENDOMETRIUM THROUGHOUT THE MENSTRUAL-CYCLE

GnRH is one of the paracrine/autocrine regulators of hCG secretion pro duced by the human trophoblast during pregnancy We hypothesized that G nRH may play a role in the embryonic/ endometrial dialogue during earl y implantation. To examine this hypothesis, we assessed GnRH and GnRH- receptor mRNA and protein expression in human endometrium throughout t he menstrual cycle of premenopausal fertile patients. Quantitation of the mRNA was performed by reverse transcription (RT)-competitive polym erase chain reaction (PCR) in the presence of a competitive cDNA fragm ent. RT-PCR revealed that unfractioned endometrium and isolated endome trial stromal and epithelial cells express GnRH and GnRH-receptor mRNA throughout all phases of the menstrual cycle. Quantitative PCR showed a dynamic pattern in the GnRH mRNA expression throughout the cycle, w ith a significant increase (p < 0.05) in the secretory phase as compar ed to the proliferative phase. Furthermore, quantitative competitive P CR of isolated glandular and stromal cells showed higher mRNA levels ( p < 0.05) in the luteal phase in both compartments. GnRH immunostainin g was localized in all major compartments, with the most intense stain ing during the luteal phase. On the basis of these data, we suggest th at during reproductive life, endometrial GnRH may play a paracrine/aut ocrine role in the early stages of implantation by modulating embryoni c trophoblastic secretion of hCG.