SPATIOTEMPORAL EXPRESSION OF PRLR IN MURINE OVIDUCT DURING PREIMPLANTATION PERIOD

Abstract

In mice, the oviduct is required for the timely accomplishment of gamete transport, fertilization, preimplantation embryo development, and to deliver a competent and healthy conceptus to the endometrium. Apart from the ovarian steroids, prolactin (PRL)from hypophysis acting through prolactin receptor (PRLR) plays a major role during early pregnancy. The present study is aimed to know the spatiotemporal localization of PRLR in the mouse oviduct during the pre- and peri-implantation phases of early pregnancy. Oviducts were collected from mice during different phases of early pregnancy, fixed in 4% paraformaldehyde, subjected to immunohistochemistry and western blotting. The intensities of immunohistochemical staining were measured in the oviductal subregions using ImageJ (Fiji) software. The expression of PRLR was principally found in the apical membrane and cytoplasm of oviductal cells, irrespective of its subregions (infundibulum, ampulla, and isthmus). Nevertheless, the intensity of PRLR varies throughout early pregnancy. The highest expression of PRLR was observed in the ciliated epithelial cells of the infundibulum and ampullary region of the oviduct on gestation day (GD) 1.5 and 2.5. However, downregulation of PRLR in the oviductal epithelial cells was noticed during the peri- and post-implantation periods. The diminished PRLR expression in the epithelial cells was maintained thereafter. Western blot analysis revealed a single protein band with an apparent molecular weight of 90 kDa. It is inferred that time specific expression pattern of PRLR along the oviductal subregions indicates the requirement of prolactin hormone and its receptors during the preimplantation period.