EXPRESSION OF GONADOTROPIN-RELEASING-HORMONE (GNRH) GENE IN HUMAN UTERINE ENDOMETRIAL TISSUE

Many peripheral reproductive tissues have been found to contain gonado trophin-releasing hormone (GnRH) and express the GnRH gene at low leve ls, presumably because the hormone functions in a paracrine/autocrine fashion. This study was designed to investigate and characterize GnRH gene expression in human endometrial tissue at different stages of the endometrial cycle. Reverse transcriptase-polymerase chain reaction (R T-PCR) analysis together with Southern blot assay demonstrated that hu man endometrial tissue expresses the proGnRH gene. RNA samples from en dometrial tissue were analysed with two pairs of oligonucleotide prime rs. Both gave a doublet 870 bases apart at the expected sizes, indicat ing that both the upstream and downstream transcriptional start sites of the GnRH gene are used in endometrial tissue and that transcripts w ith and without intron 1 were produced. Our data also demonstrated tha t utilization of the two promoters varies with the stage of the endome trial cycle. The largest difference came from the mRNA transcribed fro m the downstream promoter and without intron 1. This mRNA was expresse d at a very low level during the proliferative phase and dramatically increased almost 10-fold (P < 0.01) during the early secretory phase, and subsequently decreased 5-fold during the late secretory stage. The presence of GnRH mRNA in the endometrium, as well as the differential expression of the GnRH gene during the early secretory phase provides physiological evidence that human GnRH may play a paracrine/autocrine function in the human uterus.