Alterations in the Expression of Tight and Adherens Junction Proteins in the Hen Oviduct Following Tamoxifen Treatment

Intercellular junctions are essential for maintaining epithelial integrity, barrier function, and tissue remodeling in the female reproductive system. However, their role in the avian oviduct is poorly understood. The aim of this study was to examine the effect of tamoxifen (TMX; an estrogen receptor blocker in birds) treatment on the histoarchitecture and the abundance of transcripts and proteins, as well as the immunolocalization of key tight junction proteins (occludin, claudin 1, and ZO1) and adherens junction proteins (E-cadherin and β-catenin) in the oviduct of hens. Tissue samples were collected from all oviductal segments (i.e., the infundibulum, magnum, isthmus, shell gland, and vagina) on day 8 of the experiment, from control (laying; n = 6) hens and hens treated (6 mg/kg body weight) daily with TMX (non-laying; n = 6). Following TMX treatment for 7 consecutive days, a pause in laying and partial oviductal regression was accompanied by segment-dependent alterations in mRNA transcript abundances (examined by qRT-PCR) and/or protein abundances (determined by Western blot) of the examined junctional molecules. Furthermore, TMX treatment altered the patterns of immunofluorescent staining within the oviductal wall, concomitant with the disorganization of the luminal epithelium and tubular glands. Our results suggest that the expression and localization of tight and adherens junction proteins in the hen oviduct depend strongly on estrogen signaling. Moreover, this study provides novel insights into the regulation of these proteins, indicating their potential involvement in the molecular mechanisms that orchestrate epithelial remodeling and functioning in the hen oviduct, which may affect poultry production.