Expression and Localization of Gonadotropin-releasing Hormone Receptor in the Rat Oviduct During Pregnancy

Abstract

S U M M A R Y A recent study from our laboratory has shown cellular and ultrastructural distribution of the gonadotropin-releasing hormone (GnRH) and the relative expression of its mRNA in the rat oviduct during the postimplantation period of pregnancy (days 7, 9, 16, and 20). To determine the possible autocrine/paracrine involvement of the oviductal GnRH during pregnancy in rats, the present investigation aims at the study of the relative expression of GnRH receptor (GnRHR) mRNA by real-time PCR followed by immunolocalization of the peptide in the oviduct during pregnancy. Semiquantitative analysis of the oviductal GnRHR expression by Western blot was done by densitometry of the signal intensity. Our results indicate the expression of GnRHR mRNA in the rat oviduct throughout the postimplantation period of pregnancy with no significant difference in expression between the selected time points. Immunoreactive GnRHR peptide was localized predominantly in the cytoplasm of the luminal epithelial cells, with less expression in the cytoplasm of the stromal cells and the smooth muscles throughout the oviduct. Signal intensity of GnRHR was significantly lower during day 16 when compared to days 7 and 20. These results, for the first time, support the transcription of GnRHR mRNA and its translation to protein in the rat oviduct throughout the postimplantation period of pregnancy. The lower protein content of GnRHR by day 16 may be indicative of ligand-induced downregulation of the receptor expression. The present investigation thus strengthens our previously postulated hypothesis regarding the receptormediated autocrine/paracrine role of oviductal GnRH during pregnancy in rats.

Gonadotropin-releasing hormone and gonadotropin-releasing hormone receptor are expressed at tubal ectopic pregnancy implantation sites

“…Here we reported that both GnRH and GnRHR are localized predominantly in the fallopian tube epithelium from ectopic pregnancies, with weak expression in the fallopian tube stroma. These findings are in agreement with similar studies on the expression of GnRHR in the pregnant rat oviduct (16). At present, the role of the GnRH-GnRHR system in fallopian tube function is still poorly understood.…”

“…Previous studies have detected GnRH and GnRHR in the oviducts of cows and pregnant rats (16,30,31). Here we reported that both GnRH and GnRHR are localized predominantly in the fallopian tube epithelium from ectopic pregnancies, with weak expression in the fallopian tube stroma.…”

“…On the maternal side, GnRH and GnRHR mRNA and protein are expressed in the decidua (15). Additionally, GnRHR has been detected in rat oviduct during the postimplantation period (16). However, whether or not GnRH and GnRHR are expressed in tubal ectopic pregnancy is unknown.…”

GnRH receptor expression in human prostate cancer cells is affected by hormones and growth factors

“…Few strong positive cells (9-10%) were detected in both the models. According to other authors [23], the staining was mainly localized in the cytoplasm, with a weak positivity at the plasma membrane (Figs. 5 and 6).…”